Professional Education

  • Bachelor of Science, College Of Idaho (2011)
  • Doctor of Philosophy, North Carolina State Univ At Raleigh (2016)

Stanford Advisors

2019-20 Courses

All Publications

  • Acetylcholinesterase plays a non-neuronal, non-esterase role in organogenesis. Development (Cambridge, England) Pickett, M. A., Dush, M. K., Nascone-Yoder, N. M. 2017; 144 (15): 2764–70


    Acetylcholinesterase (AChE) is crucial for degrading acetylcholine at cholinergic synapses. In vitro studies suggest that, in addition to its role in nervous system signaling, AChE can also modulate non-neuronal cell properties, although it remains controversial whether AChE functions in this capacity in vivo Here, we show that AChE plays an essential non-classical role in vertebrate gut morphogenesis. Exposure of Xenopus embryos to AChE-inhibiting chemicals results in severe defects in intestinal development. Tissue-targeted loss-of-function assays (via microinjection of antisense morpholino or CRISPR-Cas9) confirm that AChE is specifically required in the gut endoderm tissue, a non-neuronal cell population, where it mediates adhesion to fibronectin and regulates cell rearrangement events that drive gut lengthening and digestive epithelial morphogenesis. Notably, the classical esterase activity of AChE is dispensable for this activity. As AChE is deeply conserved, widely expressed outside of the nervous system, and the target of many environmental chemicals, these results have wide-reaching implications for development and toxicology.

    View details for DOI 10.1242/dev.149831

    View details for PubMedID 28684626

    View details for PubMedCentralID PMC5560043

  • Variations in hepatic biomarkers in American alligators (Alligator mississippiensis) from three sites in Florida, USA CHEMOSPHERE Gunderson, M. P., Pickett, M. A., Martin, J. T., Hulse, E. J., Smith, S. S., Smith, L. A., Campbell, R. M., Lowers, R. H., Boggs, A. S., Guillette, L. J. 2016; 155: 180-187


    Sub-individual biomarkers are sub-lethal biological responses commonly used in the assessment of wildlife exposure to environmental contaminants. In this study, we examined the activity of glutathione-s-transferase (GST) and lactate dehydrogenase (LDH), and metallothionein (MT) concentrations among captive-raised alligator hatchlings, wild-caught juveniles, and wild-caught adults. Juveniles and adults were collected from three locations in Florida (USA) with varying degrees of contamination (i.e. Lake Apopka (organochlorine polluted site), Merritt Island National Wildlife Refuge (NWR) (metal polluted site), and Lake Woodruff NWR (reference site)). We examined whether changes in the response of these three biomarkers were age and sex dependent or reflected site-specific variations of environmental contaminants. Juvenile alligators from Merritt Island NWR had higher MT concentrations and lower GST activity compared to those from the other two sites. This outcome was consistent with higher metal pollution at this location. Sexually dimorphic patterns of MT and GST (F > M) were observed in juvenile alligators from all sites, although this pattern was not observed in adults. GST activity was lower in captive-raised alligators from Lake Apopka and Merritt Island NWR as compared to animals from Lake Woodruff NWR, suggesting a possible developmental modulator at these sites. No clear patterns were observed in LDH activity. We concluded that GST and MT demonstrate age and sex specific patterns in the alligators inhabiting these study sites and that the observed variation among sites could be due to differences in contaminant exposure.

    View details for DOI 10.1016/j.chemosphere.2016.04.018

    View details for Web of Science ID 000377736100021

    View details for PubMedID 27111470

  • Frogs as integrative models for understanding digestive organ development and evolution SEMINARS IN CELL & DEVELOPMENTAL BIOLOGY Womble, M., Pickett, M., Nascone-Yoder, N. 2016; 51: 92-105


    The digestive system comprises numerous cells, tissues and organs that are essential for the proper assimilation of nutrients and energy. Many aspects of digestive organ function are highly conserved among vertebrates, yet the final anatomical configuration of the gut varies widely between species, especially those with different diets. Improved understanding of the complex molecular and cellular events that orchestrate digestive organ development is pertinent to many areas of biology and medicine, including the regeneration or replacement of diseased organs, the etiology of digestive organ birth defects, and the evolution of specialized features of digestive anatomy. In this review, we highlight specific examples of how investigations using Xenopus laevis frog embryos have revealed insight into the molecular and cellular dynamics of digestive organ patterning and morphogenesis that would have been difficult to obtain in other animal models. Additionally, we discuss recent studies of gut development in non-model frog species with unique feeding strategies, such as Lepidobatrachus laevis and Eleutherodactylous coqui, which are beginning to provide glimpses of the evolutionary mechanisms that may generate morphological variation in the digestive tract. The unparalleled experimental versatility of frog embryos make them excellent, integrative models for studying digestive organ development across multiple disciplines.

    View details for DOI 10.1016/j.semcdb.2016.02.001

    View details for Web of Science ID 000372329800012

    View details for PubMedID 26851628