Education & Certifications
B.S., University of Evansville, Exercise Science (2009)
M.S., California State University, Fullerton, Exercise Physiology (2012)
Establishing typical values for hemocyte mortality in individual California mussels, Mytilus californianus.
Fish & shellfish immunology
Hemocytes are immune cells in the hemolymph of invertebrates that play multiple roles in response to stressors; hemocyte mortality can thus serve as an indicator of overall animal health. However, previous research has often analyzed hemolymph samples pooled from several individuals, which precludes tracking individual responses to stressors over time. The ability to track individuals is important, however, because large inter-individual variation in response to stressors can confound the interpretation of pooled samples. Here, we describe protocols for analysis of inter- and intra-individual variability in hemocyte mortality across repeated hemolymph samples of California mussels, Mytilus californianus, free from typical abiotic stressors. To assess individual variability in hemocyte mortality with serial sampling, we created four groups of 15 mussels each that were repeatedly sampled four times: at baseline (time zero) and three subsequent times separated by either 24, 48, 72, or 168 h. Hemocyte mortality was assessed by fluorescence-activated cell sorting (FACS) of cells stained with propidium iodide. Our study demonstrates that hemolymph can be repeatedly sampled from individual mussels without mortality; however, there is substantial inter- and intra-individual variability in hemocyte mortality through time that is partially dependent on the sampling interval. Across repeated samples, individual mussels' hemocyte mortality had, on average, a range of ∼6% and a standard deviation of ∼3%, which was minimized with sampling periods ≥72 h apart. Due to this intra-individual variability, obtaining ≥2 samples from a specimen will more accurately establish an individual's baseline. Pooled-sample means were similar to individual-sample means; however, pooled samples masked the individual variation in each group. Overall, these data lay the foundation for future work exploring individual mussels' temporal responses to various stressors on a cellular level.
View details for DOI 10.1016/j.fsi.2020.02.069
View details for PubMedID 32135339
Impact of heating rate on cardiac thermal tolerance in the California mussel, Mytilus californianus.
The Journal of experimental biology
Intertidal communities of wave-swept rocky shores have served as a powerful model system for experiments in ecology, and mussels (the dominant competitor for space in the mid-intertidal zone) play a central role in determining community structure in this physically stressful habitat. Consequently, our ability to account for mussels' physiological responses to thermal stress affects ecologists' abilities to predict the impacts of a warming climate on this ecosystem. Here, we examine the effect of heating rate on cardiac thermal tolerance in the ribbed mussel, Mytilus californianus, comparing populations from high and low sites in the intertidal zone where emersion duration leads to different mean daily heating rates. Two temperature-related cardiac variables were examined: 1) the critical temperature (Hcrit) at which heart rate (HR) precipitously declines, and 2) flatline temperature (FLT) where HR reaches zero. Mussels were heated in air at slow, moderate, and fast rates, and heart rate was measured via an infrared sensor affixed to the shell. Faster heating rates significantly increased Hcrit in high-, but not low-zone mussels, and Hcrit was higher in high vs. - mussels, especially at the fastest heating rate. By contrast, FLT did not differ between zones, and was minimally affected by heating rate. Since heating rate significantly impacted high- but not low-zone mussels' cardiac thermal tolerance, realistic zone-specific heating rates must be used in laboratory tests if those tests are to provide accurate information for ecological models attempting to predict the effects of increasing temperature on intertidal communities.
View details for DOI 10.1242/jeb.203166
View details for PubMedID 31395674
The effect of passive heat stress on distress andself-control in male smokers and non-smokers.
The Journal of general psychology
In the current study, we tested the effects of core body temperature increases (e.g. heat stress) on affect, self-reported physical discomfort, and subsequent self-control in male smokers and nonsmokers using a novel passive heat stress paradigm, within a distress tolerance framework. Twenty-eight men (14 smokers), completed both heat stress and control sessions in randomized order. Results revealed that increases in core body temperature were associated with increased anxiety, irritability, and body discomfort as well as decreased happiness, with stronger effects for smokers. Smokers and nonsmokers both evidenced less self-control during the heat session and did not differ on this measure, nor on a measure of interoceptive sensitivity. The current study indicates that heat stress is a viable method for studying distress tolerance in men, and suggests the value in examining dynamic changes in self-control as a function of distress. Implications will be discussed for distress tolerance in general and smokers in specific.
View details for PubMedID 30358519