Academic Appointments


Boards, Advisory Committees, Professional Organizations


  • Co-Director, SURMAR/ASIMAR (The Ocean Foundation) (2008 - Present)
  • External Advisory Board member, Puerto Rico Center for Enviornmental Neuroscience (PRCEN), Univ. Puerto Rico (2012 - Present)
  • Board member, Western Flyer Foundation (2016 - Present)

Professional Education


  • Postdoctoral, University of Pennsylvania, Biology, Physiology (1979)
  • PhD, Washington University School of Medicine, Yale University School of Medicine, Physiology and Biophysics (1978)
  • BSE, Princeton University, Electrical Engineering (1972)

Community and International Work


  • Squids4Kids, Pacific Grove, CA

    Topic

    Ocean health and marine ecology

    Partnering Organization(s)

    NOAA Southwest Fisheries Sciene Center, Monterey Bay National Marine Sancturary Foundation

    Populations Served

    K-12, science festivals

    Location

    International

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    Yes

  • Sustainable Utilization and Research of Mar de Cortes (SURMAR), Santa Rosalia, BCS, Mexico

    Topic

    Marine ecology and resource develeopment

    Partnering Organization(s)

    Intsiuto Tecnologico Superior de Mulege, The Ocean Foundation

    Populations Served

    Mexican fishing communities and undergraduate students

    Location

    International

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    Yes

Current Research and Scholarly Interests


My group was the first (and only) to deploy pop-up satellite tags and video packages (National Geographic Crittercam) on large Humboldt squid to record their second-to-second movements and color-changing behaviors. This work showed that this active predator spends a great deal of its time at depths of 300 m or more where the oxygen concentration is extremely low – less than 10% of that at the surface. This ‘oxygen minim zone’ (OMZ) is found throughout the southern half of the Gulf of California and much of the eastern Pacific Ocean, including Monterey Bay. The OMZ has been moving closer to the sea surface over the last few decades, and this aspect of marine climate change is expected to have major ecological consequences as ocean’s oxygenated surface zone becomes increasingly vertically compressed.

Our work in the Gulf of California has recently focused on the relationship between the size of Humboldt squid and environmental variation, particularly temperature at depth. Since an unusual El Niño event in 2009-10, the temperature at depths of up to 100 m has been increasing, and squid have responded by attaining maturity at a vastly smaller size and younger age than they had before 2009. Small size at maturity is normally a characteristic phenotype of this species in the tropical eastern Pacific, and the change in the squid’s life history in the Sea of Cortez is consistent with the decreasing productivity and increasing temperatures observed over the last 6 years. Humboldt squid are telling us that the Gulf of California may be changing from a seasonally highly productive, upwelling-driven system to a low productivity tropical system.

Current laboratory work on squid chromatophores uses methods of electrophysiology, cell and molecular biology and electron microscopy, through collaborations with Univ. Puerto Rico, Univ. North Carolina Chapel Hill and Univ. Kansas. A major hypothesis guiding the work is that a “horizontal” pathway for communication between chromatophores exists in the plane of the skin, and that this network can mediate chromogenic behaviors in the absence of descending motor control by the central nervous system. We use a comparative approach to take advantage of natural differences in behavioral capabilities of Humboldt squid (Dosidicus gigas) and CA market squid (Doryteuthis opalescens) that inhabit environments with extremely different visual features. Market squid are a coastal species that use spatial patterning of chromatophore displays to provide camouflage in order to match benthic features like seaweed and rocks. Humboldt squid are an open ocean species that primarily generate temporal patterning and use spatially global flashing in intra-specific signaling. We hypothesize that these striking behavioral differences will be reflected in structural and functional elements of the peripheral control pathway.

Another project examines the role of the giant axon system in controlling escape responses in both Dosidicus and Doryteuthis, with a focus on sensitivity of the system to temperature and hypoxia. Both of these environmental variables are relevant to these species in the ocean. Methods used include electrophysiology, anatomy and particle image velocimetry.

Laboratory work is carried out both at Hopkins Marine Station and at our lab facility in Santa Rosalia, BCS, Mexico.

Projects


  • Natural Chromogenic Behaviors of Squid in Oceanic Waters, Stanford Univesity (6/1/2014 - 5/31/2017)

    1. Record natural behaviors in free-swimming Humboldt squid (Dosidicus gigas) in the water column under natural lighting conditions using low-light video packages to characterize dynamic chromogenic displays that are related to intra-specific signaling and crypsis.

    2. Develop improved low-light, free-floating video packages to image behavior of marine organisms under natural lighting conditions at midwater depths, including chromogenic behaviors of squid, and to make these packages available to other researchers.

    3. Compare chromogenic behaviors and underlying structural and functional features of the chromatophore system in squid species that inhabit distinct environments with different visual features -- open ocean for Dosidicus gigas (family Ommastrephidae) versus coastal shallows for Doryteuthis opalescens, the California market squid (family Loliginidae).

    Location

    Hopkins Marirne Station and Santa Rosalia, Baja California Sur, Mexico

    Collaborators

    • Eric Berkenpas, Lead Engineer, National Geographic Remote Imaging
    • Mike Shepard, Engineer, National Geographic Remote Imaging
  • Collaborative Research: Structural and Functional Connectivity of Squid Chromatophores, Stanford Univesity (7/1/2016 - 6/30/2019)

    Squid and other cephalopods have the ability to change skin color using muscular chromatophore organs that are under direct neural control. All work on the cellular mechanisms of chromatophore control in squid has focused on three species in the family Loliginidae that inhabit coastal environments rich in benthic features like seaweed, rocks and coral. Skin-color changes in these species are associated with camouflage as well as intra-specific signaling and deimatic displays. The open ocean presents a radically different environment that is also inhabited by many squids, primarily of the family Ommastrephidae, one that includes the Humboldt squid (Dosidicus gigas). There is little light in the oceanic water column at depths inhabited by these squid during daytime, and static visual features are non-existent. Novel color-change behaviors in Dosidicus include repetitive whole-body “flashing,” used for intra-specific signaling, and chaotic-like “flickering” that may underlie crypsis in the open ocean. Although these dynamic behaviors contrast with the generally more static patterns in loliginids, squids of both families employ temporal and spatial patterning to varying degrees. It is therefore likely that basic mechanisms for controlling the chromatophore network are shared by most, if not all, squids. Descending “vertical” control from the brain to the chromatophore musculature is well established in loliginids and may account for most chromogenic behaviors in those species, but behaviors in ommastrephids like flickering may be more influenced by processes within the skin itself that permit excitation to spread from one chromatophore to another without directly involving the nervous system. This hypothetical pathway would define a “horizontal” or distributed control system in the periphery that would permit autonomous behavior within the chromatophore network. Horizontal control is relevant to the vascular bed, gut and coupled neural micro-circuits in vertebrates, and results from this project will thus influence this broader field. From a wider perspective, results of this project will be relevant to interactions of distributed (horizontal) and top-down (vertical) control mechanisms, an inherent feature of complex systems to generate non-predictable, emergent phenomena. This concept is of fundamental interest to a broad sector of society, ranging from engineering to economics to politics.

    An integrated approach will be followed to test the hypothesis that control of the chromatophore network in squid involves peripheral mechanisms that are distinct from the neuronal motor-control pathway that descends from the brain. Spontaneous chromatophore activity that is independent of canonical neural control will be isolated by experimental manipulations in loliginid squid (Doryteuthis opalescens), including chronic denervation and pharmacological block of neuronal activity with tetrodotoxin. In addition, a comparative approach will take advantage of an ommastrephid species, Dosidicus gigas, in which spontaneous, tetrodotoxin-resistant chromatophore activity is extremely prominent. Relevant methods involve cellular electrophysiology, molecular transcriptomics, immunohistochemistry with confocal microscopy and high-resolution electron microscopy. Specific aims are: 1) identify molecular and physiological properties of relevant ion channels and receptors that control excitability in the radial muscle fibers that operate individual chromatophore organs in Doryteuthis; 2) define structural, molecular and physiological features of coupling mechanisms between muscle fibers of neighboring chromatophores that define an excitatory transmission pathway within the skin; 3) elucidate the inhibitory role in controlling spontaneous chromatophore activity played by serotonin; 4) carry out parallel experiments in Dosidicus, a member of a family of ecologically important squid in which cellular studies of chromatophores have never been carried out.

    Location

    Hopkins Marirne Station and Santa Rosalia, Baja California Sur, Mexico

    Collaborators

    • Josh Rosenthal, Professor, University of Puerto Rico
    • Bill Kier, Professsor, University of North Carolina, Chapel Hill
  • Variations in water column properties of the Sea of Cortez in relation to ecosystem and climate dynamics, Stanford University and SURMAR (The Ocean Foundation) (12/1/2015 - November 30, 2018)

    Climate change is a significant threat to the ecological balance in the Gulf of California and long-term measurement of both oceanographic and biological/ecological features are necessary to understand the impacts of climate change. These effects can be exerted seasonally (the Gulf has a huge temperature variation), over the course of a year or two by a strong El Niño, or over decades by global warming and the associated phenomena of ocean acidification and oxygen minimum zone expansion. The latter change probably involves agricultural runoff and potentially sewage discharge. Although remote sensing of ocean surface properties is an excellent and cost-effective way of tracking important aspects of climate change, it cannot discern changes that are occurring hundreds of meters below the surface, and this midwater environment is critically important, either directly or indirectly, to almost all pelagic organisms, including Humboldt squid. Systematic measurements of water-column properties in the field are essential; there is simply no substitute.

    This project is designed to continue a monitoring program of water-column prperties in the Gulf of Califronia that began in 2010. Measurements of temperature, salinity, oxygen and cholorophyl concentrations are made to depths of 600 m using a standard profiling instrument from the vessel National Geographic Seabird as part of ongoing operations by Lindblad Expeditions. To our knowledge, there is no other systematic assessment of water-column properties being carried out in the Gulf of California in the area under consideration.

    Location

    Hopkins Marirne Station and Baja California Sur, Mexico

    For More Information:

2018-19 Courses


Stanford Advisees


Graduate and Fellowship Programs


All Publications


  • Same-sex sexual behaviour in an oceanic ommastrephid squid, Dosidicus gigas (Humboldt squid) MARINE BIOLOGY Hoving, H. T., Fernandez-Alvarez, F. A., Portner, E. J., Gilly, W. F. 2019; 166 (3)
  • Grouping reduces the metabolic demand of a social squid Marine Ecology Progress Series Burford, B. P., Carey, N., Gilly, W. F., Goldbogen, J. A. 2019; 612: 141-150

    View details for DOI 10.3354/meps12880

  • Functionally driven modulation of sarcomeric structure and membrane systems in the fast muscles of a copepod (Gaussia princeps). Anatomical record (Hoboken, N.J. : 2007) Glaser, N., Iyer, R., Gilly, W. F., Franzini-Armstrong, C. 2018

    Abstract

    Muscles of the mesopelagic copepod Gaussia princeps (Arthropoda, Crustacea, Calanoida) are responsible for repetitive movements of feeding and swimming appendages that are too fast to be followed by eye. This paper provides a comparative functional and ultrastructural description of five muscles that have different contraction speeds and are located within different anatomical sites. All are very fast, as indicated by a thick:thin filament ratio of 3:1 and sarcomere lengths that vary between 1 and 3mum. Measured lengths of thin and thick filaments indicate classification of the muscles into three distinct groups (short, medium and long) and predict a difference in speed of up to threefold between fibers with the shortest and longest sarcomeres. Indeed, the kicking movement of the posterior legs (with the shortest sarcomere length) is approximately three-fold faster than the simultaneous back-folding of the antennae (with the longest length). Thus, a specific relationship between speed of movement and sarcomere length is established and we can use the latter to predict the former. Regulatory systems of contraction (sarcoplasmic reticulum (SR) and transverse (T) tubules) match the different contractile properties, varying in frequency of distribution and overall content in parallel to sarcomere variations. All muscles from appendages and body musculature show a unique disposition of contractile material, SR, and T tubules found only in copepod muscles: muscle filaments are grouped in large supermyofibrils, that are riddled with frequent cylindrical shafts containing SR and T tubules. This arrangement insures a high spatial frequency of regulatory components. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/ar.23966

    View details for PubMedID 30312013

  • A Buoyancy-Controlled Lagrangian Camera Platform for In Situ Imaging of Marine Organisms in Midwater Scattering Layers IEEE JOURNAL OF OCEANIC ENGINEERING Berkenpas, E. J., Henning, B. S., Shepard, C. M., Turchik, A. J., Robinson, C. J., Portner, E. J., Li, D. H., Daniel, P. C., Gilly, W. F. 2018; 43 (3): 595–607
  • The journey of squid sperm REVIEWS IN FISH BIOLOGY AND FISHERIES Fernandez-Alvarez, F. A., Villanueva, R., Hoving, H. T., Gilly, W. F. 2018; 28 (1): 191–99
  • Myogenic activity and serotonergic inhibition in the chromatophore network of the squid Dosidicus gigas (family Ommastrephidae) and Doryteuthis opalescens (family Loliginidae) JOURNAL OF EXPERIMENTAL BIOLOGY Rosen, H. E., Gilly, W. F. 2017; 220 (24): 4669–80

    Abstract

    Seemingly chaotic waves of spontaneous chromatophore activity occur in the ommastrephid squid Dosidicus gigas in the living state and immediately after surgical disruption of all known inputs from the central nervous system. Similar activity is apparent in the loliginid Doryteuthis opalescens, but only after chronic denervation of chromatophores for 5-7 days. Electrically stimulated, neurally driven activity in intact individuals of both species is blocked by tetrodotoxin (TTX), but TTX has no effect on spontaneous wave activity in either D. gigas or denervated D. opalescens Spontaneous TTX-resistant activity of this sort is therefore likely myogenic, and such activity is eliminated in both preparations by serotonin (5-HT), a known inhibitor of chromatophore activity. Immunohistochemical techniques reveal that individual axons containing L-glutamate or 5-HT (and possibly both in a minority of processes) are associated with radial muscle fibers of chromatophores in intact individuals of both species, although the area of contact between both types of axons and muscle fibers is much smaller in D. gigas Glutamatergic and serotonergic axons degenerate completely following denervation in D. opalescens Spontaneous waves of chromatophore activity in both species are thus associated with reduced (or no) serotonergic input in comparison to the situation in intact D. opalescens Such differences in the level of serotonergic inhibition are consistent with natural chromogenic behaviors in these species. Our findings also suggest that such activity might propagate via the branching distal ends of radial muscle fibers.

    View details for DOI 10.1242/jeb.164160

    View details for Web of Science ID 000417822800017

    View details for PubMedID 29061686

  • Morphological description of egg masses and hatchlings of Lolliguncula diomedeae (Cephalopoda: Loliginidae) JOURNAL OF MOLLUSCAN STUDIES Fernandez-Alvarez, F. A., Li, D. H., Portner, E., Villanueva, R., Gilly, W. F. 2017; 83: 194-199
  • Prolonged decline of jumbo squid (Dosidicus gigas) landings in the Gulf of California is associated with chronically low wind stress and decreased chlorophyll a after El Nino 2009-2010 FISHERIES RESEARCH Robinson, C. J., Gomez-Gutierrez, J., Markaida, U., Gilly, W. F. 2016; 173: 128-138
  • Cephalopods of Pacific Latin America FISHERIES RESEARCH Markaida, U., Gilly, W. F. 2016; 173: 113-121
  • Chromogenic behaviors of the Humboldt squid (Dosidicus gigas) studied in situ with an animal-borne video package. journal of experimental biology Rosen, H., Gilly, W., Bell, L., Abernathy, K., Marshall, G. 2015; 218: 265-275

    Abstract

    Dosidicus gigas (Humboldt or jumbo flying squid) is an economically and ecologically influential species, yet little is known about its natural behaviors because of difficulties in studying this active predator in its oceanic environment. By using an animal-borne video package, National Geographic's Crittercam, we were able to observe natural behaviors in free-swimming D. gigas in the Gulf of California with a focus on color-generating (chromogenic) behaviors. We documented two dynamic displays without artificial lighting at depths of up to 70 m. One dynamic pattern, termed 'flashing' is characterized by a global oscillation (2-4 Hz) of body color between white and red. Flashing was almost always observed when other squid were visible in the video frame, and this behavior presumably represents intraspecific signaling. Amplitude and frequency of flashing can be modulated, and the phase relationship with another squid can also be rapidly altered. Another dynamic display termed 'flickering' was observed whenever flashing was not occurring. This behavior is characterized by irregular wave-like activity in neighboring patches of chromatophores, and the resulting patterns mimic reflections of down-welled light in the water column, suggesting that this behavior may provide a dynamic type of camouflage. Rapid and global pauses in flickering, often before a flashing episode, indicate that flickering is under inhibitory neural control. Although flashing and flickering have not been described in other squid, functional similarities are evident with other species.

    View details for DOI 10.1242/jeb.114157

    View details for PubMedID 25609785

  • Evolutionary history of a complex adaptation: Tetrodotoxin resistance in salamanders EVOLUTION Hanifin, C. T., Gilly, W. F. 2015; 69 (1): 232-244

    Abstract

    Understanding the processes that generate novel adaptive phenotypes is central to evolutionary biology. We used comparative analyses to reveal the history of tetrodotoxin (TTX) resistance in TTX-bearing salamanders. Resistance to TTX is a critical component of the ability to use TTX defensively but the origin of the TTX-bearing phenotype is unclear. Skeletal muscle of TTX-bearing salamanders (modern newts, family: Salamandridae) is unaffected by TTX at doses far in excess of those that block action potentials in muscle and nerve of other vertebrates. Skeletal muscle of non-TTX-bearing salamandrids is also resistant to TTX but at lower levels. Skeletal muscle TTX resistance in the Salamandridae results from the expression of TTX-resistant variants of the voltage-gated sodium channel NaV 1.4 (SCN4a). We identified four substitutions in the coding region of salSCN4a that are likely responsible for the TTX resistance measured in TTX-bearing salamanders and variation at one of these sites likely explains variation in TTX resistance among other lineages. Our results suggest that exaptation has played a role in the evolution of the TTX-bearing phenotype and provide empirical evidence that complex physiological adaptations can arise through the accumulation of beneficial mutations in the coding region of conserved proteins.

    View details for DOI 10.1111/evo.12552

    View details for Web of Science ID 000347462800018

    View details for PubMedID 25346116

  • Combined climate- and prey-mediated range expansion of Humboldt squid (Dosidicus gigas), a large marine predator in the California Current System. Global change biology Stewart, J. S., Hazen, E. L., Bograd, S. J., Byrnes, J. E., Foley, D. G., Gilly, W. F., Robison, B. H., Field, J. C. 2014; 20 (6): 1832-1843

    Abstract

    Climate-driven range shifts are ongoing in pelagic marine environments, and ecosystems must respond to combined effects of altered species distributions and environmental drivers. Hypoxic oxygen minimum zones (OMZs) in midwater environments are shoaling globally; this can affect distributions of species both geographically and vertically along with predator-prey dynamics. Humboldt (jumbo) squid (Dosidicus gigas) are highly migratory predators adapted to hypoxic conditions that may be deleterious to their competitors and predators. Consequently, OMZ shoaling may preferentially facilitate foraging opportunities for Humboldt squid. With two separate modeling approaches using unique, long-term data based on in situ observations of predator, prey, and environmental variables, our analyses suggest that Humboldt squid are indirectly affected by OMZ shoaling through effects on a primary food source, myctophid fishes. Our results suggest that this indirect linkage between hypoxia and foraging is an important driver of the ongoing range expansion of Humboldt squid in the northeastern Pacific Ocean.

    View details for DOI 10.1111/gcb.12502

    View details for PubMedID 24443361

  • Aperture effects in squid jet propulsion JOURNAL OF EXPERIMENTAL BIOLOGY Staaf, D. J., Gilly, W. F., Denny, M. W. 2014; 217 (9): 1588-1600

    Abstract

    Squid are the largest jet propellers in nature as adults, but as paralarvae they are some of the smallest, faced with the inherent inefficiency of jet propulsion at a low Reynolds number. In this study we describe the behavior and kinematics of locomotion in 1 mm paralarvae of Dosidicus gigas, the smallest squid yet studied. They swim with hop-and-sink behavior and can engage in fast jets by reducing the size of the mantle aperture during the contraction phase of a jetting cycle. We go on to explore the general effects of a variable mantle and funnel aperture in a theoretical model of jet propulsion scaled from the smallest (1 mm mantle length) to the largest (3 m) squid. Aperture reduction during mantle contraction increases propulsive efficiency at all squid sizes, although 1 mm squid still suffer from low efficiency (20%) because of a limited speed of contraction. Efficiency increases to a peak of 40% for 1 cm squid, then slowly declines. Squid larger than 6 cm must either reduce contraction speed or increase aperture size to maintain stress within maximal muscle tolerance. Ecological pressure to maintain maximum velocity may lead them to increase aperture size, which reduces efficiency. This effect might be ameliorated by nonaxial flow during the refill phase of the cycle. Our model's predictions highlight areas for future empirical work, and emphasize the existence of complex behavioral options for maximizing efficiency at both very small and large sizes.

    View details for DOI 10.1242/jeb.082271

    View details for Web of Science ID 000335583500029

    View details for PubMedID 24501132

  • Foraging ecology and movement patterns of jumbo squid (Dosidicus gigas) in the California Current System DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY Field, J. C., Elliger, C., Baltz, K., Gillespie, G. E., Gilly, W. F., Ruiz-Cooley, R. I., Pearse, D., Stewart, J. S., Matsubu, W., Walker, W. A. 2013; 95: 37-51
  • Onshore-offshore movement of jumbo squid (Dosidicus gigas) on the continental shelf DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY Stewart, J. S., Gilly, W. F., Field, J. C., Payne, J. C. 2013; 95: 193-196
  • Behavioral ecology of jumbo squid (Dosidicus gigas) in relation to oxygen minimum zones DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY Stewart, J. S., Field, J. C., Markaida, U., Gilly, W. F. 2013; 95: 197-208
  • Squid rocket science: How squid launch into air DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY O'Dor, R., Stewart, J., Gilly, W., Payne, J., Borges, T. C., Thys, T. 2013; 95: 113-118
  • Extreme plasticity in life-history strategy allows a migratory predator (jumbo squid) to cope with a changing climate GLOBAL CHANGE BIOLOGY Hoving, H. T., Gilly, W. F., Markaida, U., Benoit-Bird, K. J., Brown, Z. W., Daniel, P., Fieldk, J. C., Parassenti, L., Liu, B., Campos, B. 2013; 19 (7): 2089-2103

    Abstract

    Dosidicus gigas (jumbo or Humboldt squid) is a semelparous, major predator of the eastern Pacific that is ecologically and commercially important. In the Gulf of California, these animals mature at large size (>55 cm mantle length) in 1-1.5 years and have supported a major commercial fishery in the Guaymas Basin during the last 20 years. An El Niño event in 2009-2010, was accompanied by a collapse of this fishery, and squid in the region showed major changes in the distribution and life-history strategy. Large squid abandoned seasonal coastal-shelf habitats in 2010 and instead were found in the Salsipuedes Basin to the north, an area buffered from the effects of El Niño by tidal upwelling and a well-mixed water column. The commercial fishery also relocated to this region. Although large squid were not found in the Guaymas Basin from 2010 to 2012, small squid were abundant and matured at an unusually small mantle-length (<30 cm) and young age (approximately 6 months). Juvenile squid thus appeared to respond to El Niño with an alternative life-history trajectory in which gigantism and high fecundity in normally productive coastal-shelf habitats were traded for accelerated reproduction at small size in an offshore environment. Both small and large mature squid, were present in the Salsipuedes Basin during 2011, indicating that both life- history strategies can coexist. Hydro-acoustic data, reveal that squid biomass in this study area nearly doubled between 2010 and 2011, primarily due to a large increase in small squid that were not susceptible to the fishery. Such a climate-driven switch in size-at-maturity may allow D. gigas to rapidly adapt to and cope with El Niño. This ability is likely to be an important factor in conjunction with longerterm climate-change and the potential ecological impacts of this invasive predator on marine ecosystems.

    View details for DOI 10.1111/gcb.12198

    View details for Web of Science ID 000319963500010

    View details for PubMedID 23505049

  • Oceanographic and Biological Effects of Shoaling of the Oxygen Minimum Zone ANNUAL REVIEW OF MARINE SCIENCE, VOL 5 Gilly, W. F., Beman, J. M., Litvin, S. Y., Robison, B. H. 2013; 5: 393-420

    Abstract

    Long-term declines in oxygen concentrations are evident throughout much of the ocean interior and are particularly acute in midwater oxygen minimum zones (OMZs). These regions are defined by extremely low oxygen concentrations (<20-45 μmol kg(-1)), cover wide expanses of the ocean, and are associated with productive oceanic and coastal regions. OMZs have expanded over the past 50 years, and this expansion is predicted to continue as the climate warms worldwide. Shoaling of the upper boundaries of the OMZs accompanies OMZ expansion, and decreased oxygen at shallower depths can affect all marine organisms through multiple direct and indirect mechanisms. Effects include altered microbial processes that produce and consume key nutrients and gases, changes in predator-prey dynamics, and shifts in the abundance and accessibility of commercially fished species. Although many species will be negatively affected by these effects, others may expand their range or exploit new niches. OMZ shoaling is thus likely to have major and far-reaching consequences.

    View details for DOI 10.1146/annurev-marine-120710-100849

    View details for Web of Science ID 000316390400018

    View details for PubMedID 22809177

  • Distribution of ommastrephid paralarvae in the eastern tropical Pacific FISHERY BULLETIN Staaf, D. J., Redfern, J. V., Gilly, W. F., Watson, W., Ballance, L. T. 2013; 111 (1): 78-89

    View details for DOI 10.7755/FB.111.1.7

    View details for Web of Science ID 000314086300007

  • Oceanographic and biological effects of shoaling of the oxygen minimum zone. Annual review of marine science Gilly, W. F., Beman, J. M., Litvin, S. Y., Robison, B. H. 2013; 5: 393-420

    Abstract

    Long-term declines in oxygen concentrations are evident throughout much of the ocean interior and are particularly acute in midwater oxygen minimum zones (OMZs). These regions are defined by extremely low oxygen concentrations (<20-45 μmol kg(-1)), cover wide expanses of the ocean, and are associated with productive oceanic and coastal regions. OMZs have expanded over the past 50 years, and this expansion is predicted to continue as the climate warms worldwide. Shoaling of the upper boundaries of the OMZs accompanies OMZ expansion, and decreased oxygen at shallower depths can affect all marine organisms through multiple direct and indirect mechanisms. Effects include altered microbial processes that produce and consume key nutrients and gases, changes in predator-prey dynamics, and shifts in the abundance and accessibility of commercially fished species. Although many species will be negatively affected by these effects, others may expand their range or exploit new niches. OMZ shoaling is thus likely to have major and far-reaching consequences.

    View details for DOI 10.1146/annurev-marine-120710-100849

    View details for PubMedID 22809177

  • Locomotion and behavior of Humboldt squid, Dosidicus gigas, in relation to natural hypoxia in the Gulf of California, Mexico JOURNAL OF EXPERIMENTAL BIOLOGY Gilly, W. F., Zeidberg, L. D., Booth, J. A., Stewart, J. S., Marshall, G., Abernathy, K., Bell, L. E. 2012; 215 (18): 3175-3190

    Abstract

    We studied the locomotion and behavior of Dosidicus gigas using pop-up archival transmitting (PAT) tags to record environmental parameters (depth, temperature and light) and an animal-borne video package (AVP) to log these parameters plus acceleration along three axes and record forward-directed video under natural lighting. A basic cycle of locomotor behavior in D. gigas involves an active climb of a few meters followed by a passive (with respect to jetting) downward glide carried out in a fins-first direction. Temporal summation of such climb-and-glide events underlies a rich assortment of vertical movements that can reach vertical velocities of 3 m s(-1). In contrast to such rapid movements, D. gigas spends more than 80% of total time gliding at a vertical velocity of essentially zero (53% at 0±0.05 m s(-1)) or sinking very slowly (28% at -0.05 to -0.15 m s(-1)). The vertical distribution of squid was compared with physical features of the local water column (temperature, oxygen and light). Oxygen concentrations of ≤20 μmol kg(-1), characteristic of the midwater oxygen minimum zone (OMZ), can influence the daytime depth of squid, but this depends on location and season, and squid can 'decouple' from this environmental feature. Light is also an important factor in determining daytime depth, and temperature can limit nighttime depth. Vertical velocities were compared over specific depth ranges characterized by large differences in dissolved oxygen. Velocities were generally reduced under OMZ conditions, with faster jetting being most strongly affected. These data are discussed in terms of increased efficiency of climb-and-glide swimming and the potential for foraging at hypoxic depths.

    View details for DOI 10.1242/jeb.072538

    View details for Web of Science ID 000308041400011

    View details for PubMedID 22915711

  • Natural intrusions of hypoxic, low pH water into nearshore marine environments on the California coast CONTINENTAL SHELF RESEARCH Booth, J. A., McPhee-Shaw, E. E., Chua, P., Kingsley, E., Denny, M., Phillips, R., Bograd, S. J., Zeidberg, L. D., Gilly, W. F. 2012; 45: 108-115
  • Coordinated nocturnal behavior of foraging jumbo squid Dosidicus gigas MARINE ECOLOGY PROGRESS SERIES Benoit-Bird, K. J., Gilly, W. F. 2012; 455: 211-228

    View details for DOI 10.3354/meps09664

    View details for Web of Science ID 000304607100014

  • Marine predator migration during range expansion: Humboldt squid Dosidicus gigas in the northern California Current System MARINE ECOLOGY PROGRESS SERIES Stewart, J. S., Hazen, E. L., Foley, D. G., Bograd, S. J., Gilly, W. F. 2012; 471: 135-150

    View details for DOI 10.3354/meps10022

    View details for Web of Science ID 000312782700012

  • Egg capsule hatch rate and incubation duration of the California market squid, Doryteuthis (= Loligo) opalescens: insights from laboratory manipulations MARINE ECOLOGY-AN EVOLUTIONARY PERSPECTIVE Zeidberg, L. D., Isaac, G., Widmer, C. L., Neumeister, H., Gilly, W. F. 2011; 32 (4): 468-479
  • Diversity of conotoxin types from Conus californicus reflects a diversity of prey types and a novel evolutionary history TOXICON Elliger, C. A., Richmond, T. A., Lebaric, Z. N., PIERCE, N. T., Sweedler, J. V., Gilly, W. F. 2011; 57 (2): 311-322

    Abstract

    Most species within the genus Conus are considered to be specialists in their consumption of prey, typically feeding on molluscs, vermiform invertebrates or fish, and employ peptide toxins to immobilize prey. Conus californicus Hinds 1844 atypically utilizes a wide range of food sources from all three groups. Using DNA- and protein-based methods, we analyzed the molecular diversity of C. californicus toxins and detected a correspondingly large number of conotoxin types. We identified cDNAs corresponding to seven known cysteine-frameworks containing over 40 individual inferred peptides. Additionally, we found a new framework (22) with six predicted peptide examples, along with two forms of a new peptide type of unusual length. Analysis of leader sequences allowed assignment to known superfamilies in only half of the cases, and several of these showed a framework that was not in congruence with the identified superfamily. Mass spectrometric examination of chromatographic fractions from whole venom served to identify peptides corresponding to a number of cDNAs, in several cases differing in their degree of posttranslational modification. This suggests differential or incomplete biochemical processing of these peptides. In general, it is difficult to fit conotoxins from C. californicus into established toxin classification schemes. We hypothesize that the novel structural modifications of individual peptides and their encoding genes reflect evolutionary adaptation to prey species of an unusually wide range as well as the large phylogenetic distance between C. californicus and Indo-Pacific species.

    View details for DOI 10.1016/j.toxicon.2010.12.008

    View details for Web of Science ID 000287629400015

    View details for PubMedID 21172372

  • A diverse family of novel peptide toxins from an unusual cone snail, Conus californicus JOURNAL OF EXPERIMENTAL BIOLOGY Gilly, W. F., Richmond, T. A., Duda, T. F., Elliger, C., Lebaric, Z., Schulz, J., Bingham, J. P., Sweedler, J. V. 2011; 214 (1): 147-161

    Abstract

    Diversity among Conus toxins mirrors the high species diversity in the Indo-Pacific region, and evolution of both is thought to stem from feeding-niche specialization derived from intra-generic competition. This study focuses on Conus californicus, a phylogenetic outlier endemic to the temperate northeast Pacific. Essentially free of congeneric competitors, it preys on a wider variety of organisms than any other cone snail. Using molecular cloning of cDNAs and mass spectrometry, we examined peptides isolated from venom ducts to elucidate the sequences and post-translational modifications of two eight-cysteine toxins (cal12a and cal12b of type 12 framework) that block voltage-gated Na(+) channels. Based on homology of leader sequence and mode of action, these toxins are related to the O-superfamily, but differ significantly from other members of that group. Six of the eight cysteine residues constitute the canonical framework of O-members, but two additional cysteine residues in the N-terminal region define an O+2 classification within the O-superfamily. Fifteen putative variants of Cal12.1 toxins have been identified by mRNAs that differ primarily in two short hypervariable regions and have been grouped into three subtypes (Cal12.1.1-3). This unique modular variation has not been described for other Conus toxins and suggests recombination as a diversity-generating mechanism. We propose that these toxin isoforms show specificity for similar molecular targets (Na(+) channels) in the many species preyed on by C. californicus and that individualistic utilization of specific toxin isoforms may involve control of gene expression.

    View details for DOI 10.1242/jeb.046086

    View details for Web of Science ID 000285090000024

    View details for PubMedID 21147978

  • Effects of temperature on embryonic development of the Humboldt squid Dosidicus gigas MARINE ECOLOGY PROGRESS SERIES Staaf, D. J., Zeidberg, L. D., Gilly, W. F. 2011; 441: 165-175

    View details for DOI 10.3354/meps09389

    View details for Web of Science ID 000298061000014

  • Horizontal movements, vertical-habitat utilization and diet of the jumbo squid (Dosidicus gigas) in the Pacific Ocean off Baja California Sur, Mexico International Symposium on Climate Impacts on Oceanic Top Predators (CLIOTOP) Bazzino, G., Gilly, W. F., Markaida, U., Salinas-Zavala, C. A., Ramos-Castillejos, J. PERGAMON-ELSEVIER SCIENCE LTD. 2010: 59–71
  • Ommastrephid squids Sthenoteuthis oualaniensis and Dosidicus gigas in the eastern Pacific show convergent biogeographic breaks but contrasting population structures MARINE ECOLOGY PROGRESS SERIES Staaf, D. J., Ruiz-Cooley, R. I., Elliger, C., Lebaric, Z., Campos, B., Markaida, U., Gilly, W. F. 2010; 418: 165-U587

    View details for DOI 10.3354/meps08829

    View details for Web of Science ID 000284419700013

  • FOOD AND FEEDING OF JUMBO SQUID DOSIDICUS GIGAS IN THE CENTRAL GULF OF CALIFORNIA DURING 2005-2007 CalCOFI Conference 2007 Markaida, U., Salinas-Zavala, C. A., Rosas-Luis, R., Gilly, W. F., Booth, J. A. SCRIPPS INST OCEANOGRAPHY. 2008: 90–103
  • Remembering the Gulf: changes to the marine communities of the Sea of Cortez since the Steinbeck and Ricketts expedition of 1940 FRONTIERS IN ECOLOGY AND THE ENVIRONMENT Sagarin, A. D., Gilly, W. F., Baxter, C. H., Burnett, N., Christensen, J. 2008; 6 (7): 374-381

    View details for DOI 10.1890/070067

    View details for Web of Science ID 000259308000019

  • Oxygen declines and the shoaling of the hypoxic boundary in the California Current GEOPHYSICAL RESEARCH LETTERS Bograd, S. J., Castro, C. G., Di Lorenzo, E., Palacios, D. M., Bailey, H., Gilly, W., Chavez, F. P. 2008; 35 (12)
  • Natural egg mass deposition by the Humboldt squid (Dosidicus gigas) in the Gulf of California and characteristics of hatchlings and paralarvae JOURNAL OF THE MARINE BIOLOGICAL ASSOCIATION OF THE UNITED KINGDOM Staaf, D. J., Camarillo-Coop, S., Haddock, S. H., Nyack, A. C., Payne, J., Salinas-Zavala, C. A., Seibel, B. A., Trueblood, L., Widmer, C., Gilly, W. F. 2008; 88 (4): 759-770
  • Controlled and in situ target strengths of the jumbo squid Dosidicus gigas and identification of potential acoustic scattering sources JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA Benoit-Bird, K. J., Gilly, W. F., Au, W. W., Mate, B. 2008; 123 (3): 1318-1328

    Abstract

    This study presents the first target strength measurements of Dosidicus gigas, a large squid that is a key predator, a significant prey, and the target of an important fishery. Target strength of live, tethered squid was related to mantle length with values standardized to the length squared of -62.0, -67.4, -67.9, and -67.6 dB at 38, 70, 120, and 200 kHz, respectively. There were relatively small differences in target strength between dorsal and anterior aspects and none between live and freshly dead squid. Potential scattering mechanisms in squid have been long debated. Here, the reproductive organs had little effect on squid target strength. These data support the hypothesis that the pen may be an important source of squid acoustic scattering. The beak, eyes, and arms, probably via the sucker rings, also play a role in acoustic scattering though their effects were small and frequency specific. An unexpected source of scattering was the cranium of the squid which provided a target strength nearly as high as that of the entire squid though the mechanism remains unclear. Our in situ measurements of the target strength of free-swimming squid support the use of the values presented here in D. gigas assessment studies.

    View details for DOI 10.1121/1.2832327

    View details for Web of Science ID 000254208300009

    View details for PubMedID 18345820

  • Diving behavior of sperm whales in relation to behavior of a major prey species, the jumbo squid, in the Gulf of California, Mexico MARINE ECOLOGY PROGRESS SERIES Davis, R. W., Jaquet, N., Gendron, D., Markaida, U., Bazzino, G., Gilly, W. 2007; 333: 291-302
  • Two toxins from Conus striatus that individually induce tetanic paralysis BIOCHEMISTRY Kelley, W. P., Schulz, J. R., Jakubowski, J. A., Gilly, W. F., Sweedler, J. V. 2006; 45 (47): 14212-14222

    Abstract

    We describe structural properties and biological activities of two related O-glycosylated peptide toxins isolated from injected (milked) venom of Conus striatus, a piscivorous snail that captures prey by injecting a venom that induces a violent, spastic paralysis. One 30 amino acid toxin is identified as kappaA-SIVA (termed s4a here), and another 37 amino acid toxin, s4b, corresponds to a putative peptide encoded by a previously reported cDNA. We confirm the amino acid sequences and carry out structural analyses of both mature toxins using multiple mass spectrometric techniques. These include electrospray ionization ion-trap mass spectrometry and nanoelectrospray techniques for small volume samples, as well as matrix-assisted laser desorption/ionization time of flight mass spectrometric analysis as a complementary method to assist in the determination of posttranslational modifications, including O-linked glycosylation. Physiological experiments indicate that both s4a and s4b induce intense repetitive firing of the frog neuromuscular junction, leading to a tetanic contracture in muscle fiber. These effects apparently involve modification of voltage-gated sodium channels in motor axons. Notably, application of either s4a or s4b alone mimics the biological effects of the whole injected venom on fish prey.

    View details for DOI 10.1021/bi061485s

    View details for Web of Science ID 000242179100029

    View details for PubMedID 17115716

    View details for PubMedCentralID PMC2530915

  • Vertical and horizontal migrations by the jumbo squid Dosidicus gigas revealed by electronic tagging MARINE ECOLOGY PROGRESS SERIES Gilly, W. F., Markaida, U., Baxter, C. H., Block, B. A., Boustany, A., Zeidberg, L., Reisenbichler, K., Robison, B., Bazzino, G., SALINAS, C. 2006; 324: 1-17
  • Spawning by jumbo squid Dosidicus gigas in San Pedro Martir basin, Gulf of California, Mexico MARINE ECOLOGY PROGRESS SERIES Gilly, W. F., Elliger, C. A., Salinas, C. A., Camarilla-Coop, S., Bazzino, G., Beman, M. 2006; 313: 125-133
  • Piscivorous behavior of a temperate cone snail, Conus californicus BIOLOGICAL BULLETIN STEWART, J., Gilly, W. F. 2005; 209 (2): 146-153

    Abstract

    Most of the more than 500 species of predatory marine snails in the genus Conus are tropical or semitropical, and nearly all are thought to be highly selective regarding type of prey. Conus californicus Hinds, 1844, is unusual in that it is endemic to the North American Pacific coast and preys on a large variety of benthic organisms, primarily worms and other molluscs, and also scavenges. We studied the feeding behavior of C. californicus in captivity and found that it regularly killed and consumed live prickleback fishes (Cebidichthys violaceus and Xiphister spp.). Predation involved two behavioral methods similar to those employed by strictly piscivorous relatives. One method utilized stings delivered by radular teeth; the other involved engulfing the prey without stinging. Both methods were commonly used in combination, and individual snails sometimes employed multiple stings to subdue a fish. During the course of the study, snails became aroused by the presence of live fish more quickly, as evidenced by more rapid initiation of hunting behavior. Despite this apparent adaptation, details of prey-capture techniques and effectiveness of stings remained similar over the same period.

    View details for Web of Science ID 000233073100007

    View details for PubMedID 16260774

  • Intraspecific variation of venom injected by fish-hunting Conus snails JOURNAL OF EXPERIMENTAL BIOLOGY Jakubowski, J. A., Kelley, W. P., Sweedler, J. V., Gilly, W. F., Schulz, J. R. 2005; 208 (15): 2873-2883

    Abstract

    Venom peptides from two species of fish-hunting cone snails (Conus striatus and Conus catus) were characterized using microbore liquid chromatography coupled with matrix-assisted laser desorption/ionization-time of flight-mass spectrometry and electrospray ionization-ion trap-mass spectrometry. Both crude venom isolated from the venom duct and injected venom obtained by milking were studied. Based on analysis of injected venom samples from individual snails, significant intraspecific variation (i.e. between individuals) in the peptide complement is observed. The mixture of peptides in injected venom is simpler than that in the crude duct venom from the same snail, and the composition of crude venom is more consistent from snail to snail. While there is animal-to-animal variation in the peptides present in the injected venom, the composition of any individual's injected venom remains relatively constant over time in captivity. Most of the Conus striatus individuals tested injected predominantly a combination of two neuroexcitatory peptides (s4a and s4b), while a few individuals had unique injected-venom profiles consisting of a combination of peptides, including several previously characterized from the venom duct of this species. Seven novel peptides were also putatively identified based on matches of their empirically derived masses to those predicted by published cDNA sequences. Profiling injected venom of Conus catus individuals using matrix-assisted laser desorption/ionization-time of flight-mass spectrometry demonstrates that intraspecific variation in the mixture of peptides extends to other species of piscivorous cone snails. The results of this study imply that novel regulatory mechanisms exist to select specific venom peptides for injection into prey.

    View details for DOI 10.1242/jeb.01713

    View details for Web of Science ID 000231575800016

    View details for PubMedID 16043592

  • Decrease in inflammatory hyperalgesia by herpes vector-mediated knockdown of Na(v)1.7 sodium channels in primary afferents HUMAN GENE THERAPY Yeomans, D. C., Levinson, S. R., Peters, M. C., Koszowski, A. G., Tzabazis, A. Z., Gilly, W. F., Wilson, S. P. 2005; 16 (2): 271-277

    Abstract

    Induction of peripheral inflammation increases the expression of the Nav1.7 sodium channel in sensory neurons, potentially increasing their excitability. Peripheral inflammation also produces hyperalgesia in humans and an increase in nociceptive responsiveness in animals. To test the relationship between these two phenomena we applied a recombinant herpes simplex-based vector to the hindpaw skin of mice, which encoded both green fluorescent protein (GFP) as well as an antisense sequence to the Nav1.7 gene. The hindpaw was subsequently injected with complete Freund's adjuvant to induce robust inflammation. Application of the vector, but not a control vector encoding only GFP, prevented an increase in Nav1.7 expression in GFP-positive neurons and prevented development of hyperalgesia in both C and Adelta thermonociceptive tests. These results provide clear evidence of the involvement of an increased expression of the Nav1.7 channel in nociceptive neurons in the development of inflammatory hyperalgesia.

    View details for Web of Science ID 000227543900012

    View details for PubMedID 15761266

  • Tagging studies on the jumbo squid (Dosidicus gigas) in the Gulf of California, Mexico FISHERY BULLETIN Markaida, U., Rosenthal, J. J., Gilly, W. F. 2005; 103 (1): 219-226
  • The projectile tooth of a fish-hunting cone snail: Conus catus injects venom into fish prey using a high-speed ballistic mechanism BIOLOGICAL BULLETIN Schulz, J. R., Norton, A. G., Gilly, W. F. 2004; 207 (2): 77-79

    View details for Web of Science ID 000224912700001

    View details for PubMedID 15501848

  • A gastropod toxin selectively slows early transitions in the Shaker K channel's activation pathway JOURNAL OF GENERAL PHYSIOLOGY Sack, J. T., Aldrich, R. W., Gilly, W. F. 2004; 123 (6): 685-696

    Abstract

    A toxin from a marine gastropod's defensive mucus, a disulfide-linked dimer of 6-bromo-2-mercaptotryptamine (BrMT), was found to inhibit voltage-gated potassium channels by a novel mechanism. Voltage-clamp experiments with Shaker K channels reveal that externally applied BrMT slows channel opening but not closing. BrMT slows K channel activation in a graded fashion: channels activate progressively slower as the concentration of BrMT is increased. Analysis of single-channel activity indicates that once a channel opens, the unitary conductance and bursting behavior are essentially normal in BrMT. Paralleling its effects against channel opening, BrMT greatly slows the kinetics of ON, but not OFF, gating currents. BrMT was found to slow early activation transitions but not the final opening transition of the Shaker ILT mutant, and can be used to pharmacologically distinguish early from late gating steps. This novel toxin thus inhibits activation of Shaker K channels by specifically slowing early movement of their voltage sensors, thereby hindering channel opening. A model of BrMT action is developed that suggests BrMT rapidly binds to and stabilizes resting channel conformations.

    View details for DOI 10.1085/jgp.200409047

    View details for Web of Science ID 000221988000006

    View details for PubMedID 15148327

    View details for PubMedCentralID PMC2234574

  • All roads lead to arginine: The squid protamine gene JOURNAL OF MOLECULAR EVOLUTION Lewis, J. D., de Jong, M. E., Bagha, S. M., Tang, A., Gilly, W. F., Ausio, J. 2004; 58 (6): 673-680

    Abstract

    The protamine of squid is one of the most arginine-rich protamines (77%, mol/mol). It possesses a leading sequence that is posttranslationally removed during spermatogenesis in a manner that is analogous to that observed in some of its vertebrate protamine counterparts. In this paper we describe the gene sequence of the protamine of the squid Loligo opalescens. This represents the first complete gene sequence ever reported for an invertebrate protamine. Like those of vertebrate protamines, the messenger RNA is polyadenylated but the gene does not contain an intron. The promoter region contains the major transcriptional regulatory elements (CRE, TATA box, and CAP) that are also characteristic of the vertebrate protamine genes. It is unclear whether the similarities of protamines in species from both the deuterostome and the protostome branches represent the result of phylogenetic conservation or evolutionary convergence.

    View details for DOI 10.1007/s00239-004-2589-8

    View details for Web of Science ID 000222089700005

    View details for PubMedID 15461424

  • Characterization of a novel gastropod toxin (6-bromo-2-mercaptotryptamine) that inhibits shaker K channel activity JOURNAL OF BIOLOGICAL CHEMISTRY Kelley, W. P., Wolters, A. M., Sack, J. T., Jockusch, R. A., Jurchen, J. C., Williams, E. R., Sweedler, J. V., Gilly, W. F. 2003; 278 (37): 34934-34942

    Abstract

    A novel potassium channel antagonist has been purified from the defensive mucus secreted by Calliostoma canaliculatum, a marine snail found in the temperate coastal waters of the western Pacific. The toxin is expelled from the hypobranchial gland as part of a defensive response and is contained within a viscous matrix that minimizes dilution and degradation. The active compound was isolated by multistage microbore HPLC separations followed by bioactivity assays. Nuclear magnetic resonance, combined with electrospray ionization Fourier-transform ion cyclotron resonance and electrospray ionization ion trap mass spectrometry indicate that the active component is a heretofore unknown indole-derivative, a disulfide-linked dimer of 6-bromo-2-mercaptotryptamine (BrMT). Exudates from the hypobranchial glands of various marine mollusks have been sources for dye compounds such as 6-6 dibromoindigo, the ancient dye Tyrian purple. BrMT represents the first correlation of a hypobranchial gland exudate with a molecular response. Voltage clamp experiments with a number of K channel subtypes indicate that BrMT inhibits certain voltage-gated K channels of the Kv1 subfamily.

    View details for DOI 10.1074/jbc.M301271200

    View details for Web of Science ID 000185164400025

    View details for PubMedID 12815055

  • Cloning and characterization of an ionotropic glutamate receptor subunit expressed in the squid nervous system EUROPEAN JOURNAL OF NEUROSCIENCE Battaglia, A. A., Nardi, G., Steinhardt, A., Novakovic, A., Gentile, S., Idelson, P. I., Gilly, W. F., De Santis, A. 2003; 17 (11): 2256-2266

    Abstract

    In this paper we describe the cloning of a putative ionotropic glutamate receptor subunit, SqGluR, and its distribution in the nervous system of the squid. A full-length cDNA was assembled from a cDNA library of the stellate ganglion/giant fibre lobe complex of Loligo opalescens. The deduced amino acid sequence of the mature SqGluR displayed 44-46% amino acid identity with mammalian GluR1-GluR4 and 53% with Lym-eGluR1 from Lymnaea stagnalis. In situ hybridizations in adult squid confirmed that the SqGluR mRNA is abundant in giant fibre lobe neurons, in large, presumptive motor neurons of the stellate ganglion proper and in the supraoesophageal and optic lobes of the central nervous system. In newborn squid, SqGluR mRNA expression was detected throughout the nervous system but not elsewhere. A synthetic peptide corresponding to the last 15 amino acids of the SqGluR C-terminus was used to generate polyclonal antibodies, which were used for immunoblot analysis to demonstrate widespread expression in the squid central and peripheral nervous systems. Injection of the synthetic peptide into the postsynaptic side of the giant synapse inhibited synaptic transmission.

    View details for DOI 10.1046/j.1460-9568.2003.02680.x

    View details for Web of Science ID 000183634700003

    View details for PubMedID 12814359

  • Identified ion channels in the squid nervous system NEUROSIGNALS Rosenthal, J. J., Gilly, W. F. 2003; 12 (3): 126-141

    Abstract

    Our modern understanding of channels as discrete voltage-sensitive and ion-selective entities comes largely from a series of classical studies using the squid giant axon. This system has also been critical for understanding how transporters and synaptic transmission operate. This review outlines attempts to assign molecular identities to the extensively studied physiological properties of this system. As it turns out, this is no simple task. Molecular candidates for voltage-gated Na(+), K(+), and Ca(2+) channels, as well as ion transporters have been isolated from the squid nervous system. Both physiological and molecular approaches have been used to equate these cloned gene products with their native counterparts. In the case of the delayed rectifier K(+) conductance, the most thoroughly studied example, two major issues further complicate the equation. First, the ability of K(+) channel monomers to form heteromultimers with unique properties must be considered. Second, squid K(+) channel mRNAs are extensively edited, a process that can generate a wide variety of channel proteins from a common gene. The giant axon system is beginning to play an important role in understanding the biological relevance of this latter process.

    View details for DOI 10.1159/000072160

    View details for Web of Science ID 000184937000003

    View details for PubMedID 12904686

  • Inactivation and pharmacological properties of sqKv1A homotetramers in Xenopus oocytes cannot account for behavior of the squid "delayed rectifier" k(+) conductance BIOPHYSICAL JOURNAL Jerng, H. H., Gilly, W. F. 2002; 82 (6): 3022-3036

    Abstract

    Considerable published evidence suggests that alpha-subunits of the cloned channel sqKv1A compose the "delayed rectifier" in the squid giant axon system, but discrepancies regarding inactivation properties of cloned versus native channels exist. In this paper we define the mechanism of inactivation for sqKv1A channels in Xenopus oocytes to investigate these and other discrepancies. Inactivation of sqKv1A in Xenopus oocytes was found to be unaffected by genetic truncation of the N-terminus, but highly sensitive to certain amino acid substitutions around the external mouth of the pore. External TEA and K(+) ions slowed inactivation of sqKv1A channels in oocytes, and chloramine T (Chl-T) accelerated inactivation. These features are all consistent with a C-type inactivation mechanism as defined for Shaker B channels. Treatment of native channels in giant fiber lobe neurons with TEA or high K(+) does not slow inactivation, nor does Chl-T accelerate it. Pharmacological differences between the two channel types were also found for 4-aminopyridine (4AP). SqKv1A's affinity for 4AP was poor at rest and increased after activation, whereas 4AP block occurred much more readily at rest with native channels than when they were activated. These results suggest that important structural differences between sqKv1A homotetramers and native squid channels are likely to exist around the external and internal mouths of the pore.

    View details for Web of Science ID 000175802700019

    View details for PubMedID 12023225

    View details for PubMedCentralID PMC1302090

  • Selective open-channel block of Shaker (Kv1) potassium channels by S-nitrosodithiothreitol (SNDTT) JOURNAL OF GENERAL PHYSIOLOGY Brock, M. W., Mathes, C., Gilly, W. F. 2001; 118 (1): 113-133

    Abstract

    Large quaternary ammonium (QA) ions block voltage-gated K(+) (Kv) channels by binding with a 1:1 stoichiometry in an aqueous cavity that is exposed to the cytoplasm only when channels are open. S-nitrosodithiothreitol (SNDTT; ONSCH(2)CH(OH)CH(OH)CH(2)SNO) produces qualitatively similar "open-channel block" in Kv channels despite a radically different structure. SNDTT is small, electrically neutral, and not very hydrophobic. In whole-cell voltage-clamped squid giant fiber lobe neurons, bath-applied SNDTT causes reversible time-dependent block of Kv channels, but not Na(+) or Ca(2)+ channels. Inactivation-removed ShakerB (ShBDelta) Kv1 channels expressed in HEK 293 cells are similarly blocked and were used to study further the action of SNDTT. Dose-response data are consistent with a scheme in which two SNDTT molecules bind sequentially to a single channel, with binding of the first being sufficient to produce block. The dissociation constant for the binding of the second SNDTT molecule (K(d2) = 0.14 mM) is lower than that of the first molecule (K(d1) = 0.67 mM), indicating cooperativity. The half-blocking concentration (K(1/2)) is approximately 0.2 mM. Steady-state block by this electrically neutral compound has a voltage dependence (about -0.3 e(0)) similar in magnitude but opposite in directionality to that reported for QA ions. Both nitrosyl groups on SNDTT (one on each sulfur atom) are required for block, but transfer of these reactive groups to channel cysteine residues is not involved. SNDTT undergoes a slow intramolecular reaction (tau approximately 770 s) in which these NO groups are liberated, leading to spontaneous reversal of the SNDTT effect. Competition with internal tetraethylammonium indicates that bath-applied SNDTT crosses the cell membrane to act at an internal site, most likely within the channel cavity. Finally, SNDTT is remarkably selective for Kv1 channels. When individually expressed in HEK 293 cells, rat Kv1.1-1.6 display profound time-dependent block by SNDTT, an effect not seen for Kv2.1, 3.1b, or 4.2.

    View details for Web of Science ID 000169782800010

    View details for PubMedID 11429448

    View details for PubMedCentralID PMC2233744

  • Interaction of a toxin from the scorpion Tityus serrulatus with a cloned K+ channel from squid (sqKv1A) BIOCHEMISTRY Ellis, K. C., Tenenholz, T. C., Jerng, H., Hayhurst, M., Dudlak, C. S., Gilly, W. F., Blaustein, M. P., Weber, D. J. 2001; 40 (20): 5942-5953

    Abstract

    A toxin from the scorpion Tityus serrulatus (TsTX-Kalpha) blocks native squid K(+) channels and their cloned counterpart, sqKv1A, at pH 8 ((native)K(d) approximately 20 nM; (sqKv1A)K(d) approximately 10 nM). In both cases, decreasing the pH below 7.0 significantly diminishes the TsTX-Kalpha effect (pK = 6.6). In the cloned squid channel, the pH dependence of the block is abolished by a single point mutation (H351G), and no change in toxin affinity was observed at higher pH values (pH > or =8.0). To further investigate the TsTX-Kalpha-sqKv1A interaction, the three-dimensional structure of TsTX-Kalpha was determined in solution by NMR spectroscopy, and a model of the TsTX-Kalpha-sqKv1A complex was generated. As found for other alpha-K toxins such as charybdotoxin (CTX), site-directed mutagenesis at toxin residue K27 (K27A, K27R, and K27E) significantly reduced the toxin's affinity for sqKv1A channels. This is consistent with the TsTX-Kalpha-sqKv1A model reported here, which has K27 of the toxin inserted into the ion conduction pathway of the K(+) channel. This toxin-channel model also illustrates a possible mechanism for the pH-dependent block whereby lysine residues from TsTX-Kalpha (K6 and K23) are repelled by protonated H351 on sqKv1A at low pH.

    View details for Web of Science ID 000168932900011

    View details for PubMedID 11352729

  • Mass spectrometric survey of peptides in cephalopods with an emphasis on the FMRFamide-related peptides JOURNAL OF EXPERIMENTAL BIOLOGY Sweedler, J. V., Li, L. J., Floyd, P., Gilly, W. 2000; 203 (23): 3565-3573

    Abstract

    A matrix-assisted laser desorption/ionization (MALDI) mass spectrometric (MS) survey of the major peptides in the stellar, fin and pallial nerves and the posterior chromatophore lobe of the cephalopods Sepia officinalis, Loligo opalescens and Dosidicus gigas has been performed. Although a large number of putative peptides are distinct among the three species, several molecular masses are conserved. In addition to peptides, characterization of the lipid content of the nerves is reported, and these lipid peaks account for many of the lower molecular masses observed. One conserved set of peaks corresponds to the FMRFamide-related peptides (FRPs). The Loligo opalescens FMRFa gene has been sequenced. It encodes a 331 amino acid residue prohormone that is processed into 14 FRPs, which are both predicted by the nucleotide sequence and confirmed by MALDI MS. The FRPs predicted by this gene (FMRFa, FLRFa/FIRFa and ALSGDAFLRFa) are observed in all three species, indicating that members of this peptide family are highly conserved across cephalopods.

    View details for Web of Science ID 000165956000005

    View details for PubMedID 11060217

  • Role of prey-capture experience in the development of the escape response in the squid Loligo opalescens: A physiological correlate in an identified neuron JOURNAL OF EXPERIMENTAL BIOLOGY Preuss, T., Gilly, W. F. 2000; 203 (3): 559-565

    Abstract

    Although extensively used for biophysical studies, the squid giant axon system remains largely unexplored in regard to in vivo function and modulation in any biologically relevant context. Here we show that successful establishment of the recruitment pattern for the giant axon in the escape response elicited by a brief electrical stimulus depends on prey-capture experience early in life. Juvenile squid fed only slow-moving, easy-to-capture prey items (Artemia salina) develop deficits in coordinating activity in the giant axon system with that of a parallel set of non-giant motor axons during escape responses. These deficits are absent in cohorts fed fast-moving, challenging prey items (copepods). These results suggest that the acquisition of inhibitory control over the giant axon system is experience-dependent and that both prey-capture and escape behavior depend on this control.

    View details for Web of Science ID 000085498100013

    View details for PubMedID 10637184

  • A family of delayed rectifier Kv1 cDNAs showing cell type-specific expression in the squid stellate ganglion giant fiber lobe complex JOURNAL OF NEUROSCIENCE Rosenthal, J. J., Liu, T. I., Gilly, W. F. 1997; 17 (13): 5070-5079

    Abstract

    Squid giant axons are formed by giant fiber lobe (GFL) neurons of the stellate ganglion (SG). Other large motoneurons in the SG form a parallel system. A small family of cDNAs (SqKv1A-D) encoding Kv1 alpha-subunits was identified in a squid (Loligo opalescens) SG/GFL library. Members have distinct 5' untranslated regions (UTRs) and initial coding regions, but beyond a certain point (nucleotide 34 of SqKv1A) only nine differences exist. 3' UTRs are identical. Predicted alpha-subunits are nearly identical, and only the N termini differ significantly, primarily in length. RNase protection assays that use RNA isolated from specific SG regions show that SqKv1A mRNA is expressed prominently in the GFL but not in the SG proper. SqKv1B yields the opposite pattern. SqKv1D also is expressed only in the SG. SqKv1C expression was not detectable. In situ hybridizations confirm these results and reveal that SqKv1B mRNA is abundant in many large neurons of the SG, whereas SqKv1D expression is limited to small isolated clusters of neurons. SqKv1A and B are thus the predominant Kv1 mRNAs in the SG/GFL complex. Activation properties of SqKv1A and B channels expressed in oocytes are very similar to one another and compare favorably with properties of native delayed rectifier channels in GFL neurons and large SG neurons. The Kv1 complement in these squid neurons thus seems to be relatively simple. Several differences exist between cloned and native channels, however, and may reflect differences in the cellular environments of oocytes and neurons.

    View details for Web of Science ID A1997XE95200016

    View details for PubMedID 9185544

  • Fast and slow activation kinetics of voltage-gated sodium channels in molluscan neurons JOURNAL OF NEUROPHYSIOLOGY Gilly, W. F., Gillette, R., McFarlane, M. 1997; 77 (5): 2373-2384

    Abstract

    Whole cell patch-clamp recordings of Na current (I(Na)) were made under identical experimental conditions from isolated neurons from cephalopod (Loligo, Octopus) and gastropod (Aplysia, Pleurobranchaea, Doriopsilla) species to compare properties of activation gating. Voltage dependence of peak Na conductance (gNa) is very similar in all cases, but activation kinetics in the gastropod neurons studied are markedly slower. Kinetic differences are very pronounced only over the voltage range spanned by the gNa-voltage relation. At positive and negative extremes of voltage, activation and deactivation kinetics of I(Na) are practically indistinguishable in all species studied. Voltage-dependent rate constants underlying activation of the slow type of Na channel found in gastropods thus appear to be much more voltage dependent than are the equivalent rates in the universally fast type of channel that predominates in cephalopods. Voltage dependence of inactivation kinetics shows a similar pattern and is representative of activation kinetics for the two types of Na channels. Neurons with fast Na channels can thus make much more rapid adjustments in the number of open Na channels at physiologically relevant voltages than would be possible with only slow Na channels. This capability appears to be an adaptation that is highly evolved in cephalopods, which are well known for their high-speed swimming behaviors. Similarities in slow and fast Na channel subtypes in molluscan and mammalian neurons are discussed.

    View details for Web of Science ID A1997WZ56300011

    View details for PubMedID 9163364

  • Fast inactivation of delayed rectifier K conductance in squid giant axon and its cell bodies JOURNAL OF GENERAL PHYSIOLOGY Mathes, C., Rosenthal, J. J., Armstrong, C. M., Gilly, W. F. 1997; 109 (4): 435-448

    Abstract

    Inactivation of delayed rectifier K conductance (gk) was studied in squid giant axons and in the somata of giant fiber lobe (GFL) neurons. Axon measurements were made with an axial wire voltage clamp by pulsing to VK (approximately -10 mV in 50-70 mM external K) for a variable time and then assaying available gK with a strong, brief test pulse. GFL cells were studied with whole-cell patch clamp using the same prepulse procedure as well as with long depolarizations. Under our experimental conditions (12-18 degrees C, 4 mM internal MgATP) a large fraction of gK inactivates within 250 ms at -10 mV in both cell bodies and axons, although inactivation tends to be more complete in cell bodies. Inactivation in both preparations shows two kinetic components. The faster component is more temperature-sensitive and becomes very prominent above 12 degrees C. Contribution of the fast component to inactivation shows a similar voltage dependence to that of gK, suggesting a strong coupling of this inactivation path to the open state. Omission of internal MgATP or application of internal protease reduces the amount of fast inactivation. High external K decreases the amount of rapidly inactivating IK but does not greatly alter inactivation kinetics. Neither external nor internal tetraethylammonium has a marked effect on inactivation kinetics. Squid delayed rectifier K channels in GFL cell bodies and giant axons thus share complex fast inactivation properties that do not closely resemble those associated with either C-type or N-type inactivation of cloned Kvl channels studied in heterologous expression systems.

    View details for Web of Science ID A1997WT51900004

    View details for PubMedID 9101403

    View details for PubMedCentralID PMC2219430

  • All-or-none contraction and sodium channels in a subset of circular muscle fibers of squid mantle BIOLOGICAL BULLETIN Gilly, W. F., Preuss, T., McFarlane, M. B. 1996; 191 (3): 337-340

    Abstract

    Motor function in squid (Loligo) mantle reflects the highly coordinated activity of two motor pathways associated with giant and non-giant motor axons that respectively produce all-or-none and graded contractions in mantle muscle. Whereas both types of axons innervate circular mantle muscle fibers, precise nerve-muscle relationships remain unclear. Are squid like most invertebrates, in which single muscle fibers receive dual innervation from giant and non-giant motor axons, or is squid mantle configured more like vertebrates, in which parallel motor axon systems innervate distinct fast and slow muscle fibers? In this report, we describe giant and nongiant motor pathways that appear to control different pools of circular muscle fibers in squid. A subset of circular muscle fibers possesses large Na currents, and these fibers are proposed to employ Na-dependent action potentials to produce fast, all-or-none muscle twitches associated with giant axon stimulation.

    View details for Web of Science ID A1996WA83400001

    View details for PubMedID 8976593

  • Molecular identification of SqKv1A - A candidate for the delayed rectifier K channel in squid giant axon JOURNAL OF GENERAL PHYSIOLOGY ROSENTHAL, J. C., Vickery, R. G., Gilly, W. F. 1996; 108 (3): 207-219

    Abstract

    We have cloned the cDNA for a squid Kvl potassium channel (SqKv1A). SqKv1A mRNA is selectively expressed in giant fiber lobe (GFL) neurons, the somata of the giant axons. Western blots detect two forms of SqKv1A in both GFL neuron and giant axon samples. Functional properties of SqKv1A currents expressed in Xenopus oocytes are very similar to macroscopic currents in GFL neurons and giant axons. Macroscopic K currents in GFL neuron cell bodies, giant axons, and in Xenopus oocytes expressing SqKv1A, activate rapidly and inactivate incompletely over a time course of several hundred ms. Oocytes injected with SqKv1A cRNA express channels of two conductance classes, estimated to be 13 and 20 pS in an internal solution containing 470 mM K. SqKv1A is thus a good candidate for the "20 pS" K channel that accounts for the majority of rapidly activating K conductance in both GFL neuron cell bodies and the giant axon.

    View details for Web of Science ID A1996VF64200008

    View details for PubMedID 8882864

    View details for PubMedCentralID PMC2229315

  • QUANTIFICATION OF L-DOPA AND DOPAMINE IN SQUID INK - IMPLICATIONS FOR CHEMORECEPTION BIOLOGICAL BULLETIN Lucero, M. T., Farrington, H., Gilly, W. F. 1994; 187 (1): 55-63

    Abstract

    Squid ink is an alarm substance that both confuses predators and alerts conspecifics to the presence of danger. Although the ejection of ink is a powerful visual stimulus, studies also indicate a chemical component to the signal. Squid ink is composed mainly of melanin pigments, but the nonpigmented portion of the ink contains the enzymes and precursors of melanin synthesis. Our previous behavioral studies showed that squid olfactory organs detect L-dopa, a key chemical in melanogenesis. Squid olfactory neurons also respond to dopamine, a biogenic amine not previously described in squid ink. We performed HPLC on ink taken from the ink sacs of adult Loligo opalescens. The ink was conjugated with orthophthaldialdehyde (OPA) and injected into the HPLC, and amine-containing compounds were detected fluorometrically. Standard curves constructed for L-dopa and dopamine allowed quantitation from individual ink sacs. We found that L-dopa was present in undiluted ink at a mean concentration of 1.15 mM and was significantly greater than the mean dopamine concentration of 0.19 mM. These values are greater than those at which both compounds are effective in behavioral and electrophysiological experiments. In addition we found that an unidentified antioxidant in the ink may prevent rapid oxidation of L-dopa and dopamine following dilution in seawater.

    View details for Web of Science ID A1994PD17700007

  • AMINO-ACID-SEQUENCE OF A PUTATIVE SODIUM-CHANNEL EXPRESSED IN THE GIANT-AXON OF THE SQUID LOLIGO-OPALESCENS PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Rosenthal, J. J., Gilly, W. F. 1993; 90 (21): 10026-10030

    Abstract

    A full-length cDNA encoding a putative Na+ channel (GFLN1) has been cloned from a library prepared from the stellate ganglion of Loligo opalescens. The cDNA encodes a predicted protein of 1784 amino acids. Regions of the GFLN1 protein with defined functional importance (membrane span S4, the SS1 and SS2 segments, and interdomain III-IV) are highly conserved among all vertebrate Na+ channel alpha-subunit structures. Northern blot hybridization and RNase protection assays verify that mRNA corresponding to GFLN1 is expressed in neurons of the giant fiber lobe that form the giant axon. We propose that GFLN1 encodes the Na+ channel that has been extensively studied in the squid axon.

    View details for Web of Science ID A1993MF29600059

    View details for PubMedID 8234251

    View details for PubMedCentralID PMC47706

  • ELECTRICAL RESPONSES TO CHEMICAL-STIMULATION OF SQUID OLFACTORY RECEPTOR-CELLS JOURNAL OF EXPERIMENTAL BIOLOGY Lucero, M. T., Horrigan, F. T., Gilly, W. F. 1992; 162: 231-249
  • ACCESS RESISTANCE AND SPACE CLAMP PROBLEMS ASSOCIATED WITH WHOLE-CELL PATCH CLAMPING METHODS IN ENZYMOLOGY Armstrong, C. M., Gilly, W. F. 1992; 207: 100-122

    View details for Web of Science ID A1992JM50000005

    View details for PubMedID 1528114

  • BEHAVIORAL-RESPONSES TO CHEMICAL-STIMULATION OF THE OLFACTORY ORGAN IN THE SQUID LOLIGO-OPALESCENS JOURNAL OF EXPERIMENTAL BIOLOGY Gilly, W. F., Lucero, M. T. 1992; 162: 209-229
  • DEVELOPMENT OF GIANT MOTOR AXONS AND NEURAL CONTROL OF ESCAPE RESPONSES IN SQUID EMBRYOS AND HATCHLINGS BIOLOGICAL BULLETIN Gilly, W. F., Hopkins, B., Mackie, G. O. 1991; 180 (2): 209-220
  • CONTROL OF THE SPATIAL-DISTRIBUTION OF SODIUM-CHANNELS IN GIANT FIBER LOBE NEURONS OF THE SQUID NEURON Gilly, W. F., Lucero, M. T., Horrigan, F. T. 1990; 5 (5): 663-674

    Abstract

    Na+ channels are present at high density in squid giant axon but are absent from its somata in the giant fiber lobe (GFL) of the stellate ganglion. GFL cells dispersed in vitro maintain growing axons and develop a Na+ channel distribution similar to that in vivo. Tunicamycin, a glycosylation inhibitor, selectively disrupts the spatially appropriate, high level expression of Na+ channels in axonal membrane but has no effect on expression in cell bodies, which show low level, inappropriate expression in vitro. This effect does not appear to involve alteration in Na+ channel turnover or axon viability. K+ channel distribution is unaffected. Thus, glycosylation appears to be involved in controlling Na+ channel localization in squid neurons.

    View details for Web of Science ID A1990EJ86800010

    View details for PubMedID 2171590

  • JET-PROPELLED ESCAPE IN THE SQUID LOLIGO-OPALESCENS - CONCERTED CONTROL BY GIANT AND NON-GIANT MOTOR AXON PATHWAYS PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Otis, T. S., Gilly, W. F. 1990; 87 (8): 2911-2915

    Abstract

    Recordings of stellar nerve activity were made during escape responses in living squid. Short-latency activation of the giant axons is triggered by light-flash stimulation that elicits a stereotyped startle-escape response and powerful jet. Many other types of stimuli produce a highly variable, delayed-escape response with strong jetting primarily controlled by a small axon motor pathway. In such cases, activation of the giant axons is not necessary for a vigorous escape jet. When they are utilized, the giant axons are not activated until well after the non-giant system initiates the escape response, and excitation is critically timed to boost the rise in intramantle pressure. Squid thus show at least two escape modes in which the giant axons can contribute in different ways to the control of a highly flexible behavior.

    View details for Web of Science ID A1990CZ29900010

    View details for PubMedID 2326255

  • MOBILIZATION OF A COORDINATED ESCAPE RESPONSE BY GIANT-AXONS IN THE OPHIUROID, OPHIOPTERIS-PAPILLOSA JOURNAL OF EXPERIMENTAL BIOLOGY Yee, A., Burkhardt, J., Gilly, W. F. 1987; 128: 287-305
  • CHARGE MOVEMENT AND DEPOLARIZATION CONTRACTION COUPLING IN ARTHROPOD VS VERTEBRATE SKELETAL-MUSCLE PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Scheuer, T., Gilly, W. F. 1986; 83 (22): 8799-8803

    Abstract

    Voltage-dependent charge movement has been characterized in arthropod skeletal muscle. Charge movement in scorpion (Centuroides sculpturatus) muscle is distinguishable from that in vertebrate skeletal muscle by criteria of kinetics, voltage dependence, and pharmacology. The function of scorpion charge movement is gating of calcium channels in the sarcolemma, and depolarization-contraction coupling relies on calcium influx through these channels.

    View details for Web of Science ID A1986E906700076

    View details for PubMedID 2430301

    View details for PubMedCentralID PMC387019

  • MORPHOLOGICAL AND PHYSIOLOGICAL-PROPERTIES OF NON-STRIATED MUSCLE FROM THE TUNICATE, CIONA-INTESTINALIS - PARALLELS WITH VERTEBRATE SKELETAL-MUSCLE TISSUE & CELL Nevitt, G., Gilly, W. F. 1986; 18 (3): 341-360

    Abstract

    Non-striated muscle from the longitudinal body wall muscle in an adult ascidian (tunicate) is characterized morphologically and physiologically. These muscles are unique among chordate non-striated (i.e. 'smooth') muscles in that they are composed of discrete bundles of several small diameter (4-10 microns) muscle cells (fibers) arranged in parallel functional units. Each bundle is wrapped by a basal lamina, and at least some appear to be directly innervated at a neuromuscular junction similar to an end plate. In these regards, a bundle of Ciona smooth muscle cells is analogous to a skeletal muscle fiber of a vertebrate. This analogy also extends to physiological properties. Ciona muscle generates a rapid all-or-none Ca action potential which gives rise to a brisk twitch with brief latency. These anatomical and physiological adaptations are discussed in terms of the evolution of vertebrate skeletal muscle.

    View details for Web of Science ID A1986C895800004

    View details for PubMedID 3738887

  • IONIC BASIS OF ACTION-POTENTIAL PROPAGATION ALONG 2 CLASSES OF GIANT-AXONS IN THE OPHIUROID, OPHIOPTERIS-PAPILLOSA JOURNAL OF EXPERIMENTAL BIOLOGY TUFT, P. J., Gilly, W. F. 1984; 113 (NOV): 337-?
  • MECHANICAL-PROPERTIES AND CONTROL OF NON-MUSCULAR CATCH IN SPINE LIGAMENTS OF THE SEA-URCHIN, STRONGYLOCENTROTUS-FRANCISCANUS JOURNAL OF EXPERIMENTAL BIOLOGY Diab, M., Gilly, W. F. 1984; 111 (JUL): 155-170
  • THRESHOLD CHANNELS - A NOVEL TYPE OF SODIUM-CHANNEL IN SQUID GIANT-AXON NATURE Gilly, W. F., Armstrong, C. M. 1984; 309 (5967): 448-450

    Abstract

    Sodium channels in nerve and muscle cells are functionally similar across wide phylogenetic boundaries and are usually thought to represent a single, homogeneous population that initiates the action potential at threshold and unerringly transmits it along the surface membrane. In marked contrast, many cell types are known to have several distinct potassium permeability systems. Distinguishable populations of Na channels have been reported in a few cell types, however, including denervated skeletal muscle, embryonic cardiac muscle, Purkinje cell somata and non-myelinated axons at low temperature. We report here that in squid giant axon, in standard experimental conditions, there are two functionally distinct populations of Na channels. The newly discovered population accounts for only a few per cent of the total Na permeability. The channels are selectively activated by small depolarizations and have very slow closing kinetics. Because these channels activate at voltages near the resting potential and tend to stay open for long times, they must dominate behaviour of the axon membrane in the threshold region for action potential initiation.

    View details for Web of Science ID A1984ST80800052

    View details for PubMedID 6328313

  • CONTRACTILE ACTIVATION IN SCORPION STRIATED-MUSCLE FIBERS - DEPENDENCE ON VOLTAGE AND EXTERNAL CALCIUM JOURNAL OF GENERAL PHYSIOLOGY Gilly, W. F., Scheuer, T. 1984; 84 (3): 321-345

    Abstract

    Excitation-contraction coupling was characterized in scorpion striated muscle fibers using standard microelectrode techniques as employed in studies on vertebrate skeletal muscle. The action potential of scorpion muscle consists of two phases of regenerative activity. A relatively fast, overshooting initial spike is followed by a prolonged after-discharge of smaller, repetitive spikes. This after-discharge is accompanied by a twitch that relaxes promptly upon repolarization. Twitches fail in Na-free, tetrodotoxin (TTX)-containing, or Ca-free media. However, caffeine causes contractures in muscles paralyzed by Na- and Ca-free solutions. Experiments on muscle fibers voltage-clamped at a point with two microelectrodes in Na-free or TTX-containing media indicate that: (a) the strength-duration relation for threshold contractions has a shape similar to that in frog muscle, but mean values are displaced approximately 20 mV in the positive direction; (b) tetracaine exerts a parallel effect on strength-duration curves from scorpion and frog; (c) contractile activation in scorpion is abolished in Ca-free media; and (d) the contractile threshold is highly correlated with the occurrence of inward Ca current for pulses of all durations. Thus, the voltage dependence of contractile activation in scorpion and frog muscle is similar. However, the preparations differ in their dependence on extracellular Ca for contraction. These results are discussed in relation to possible mechanisms coupling tubular depolarization to Ca release from the sarcoplasmic reticulum in vertebrate and invertebrate skeletal muscle.

    View details for Web of Science ID A1984TJ95900001

    View details for PubMedID 6481333

    View details for PubMedCentralID PMC2228741