"An endogenous regulated circannual body weight cycle is a mirror of the
environment, reflecting the seasonal alternation between (food) abundance and scarcity." - Nicholas Mrosovsky, Rheostasis: The Physiology of Change
environment, reflecting the seasonal alternation between (food) abundance and scarcity." - Nicholas Mrosovsky, Rheostasis: The Physiology of Change
PhD Research
Colorado State University
Supervisor: Dr. Cory Williams
Colorado State University
Supervisor: Dr. Cory Williams
Neuroendocrine mechanisms responsible for circannual shifts in appetite and body weight
Seasonally hibernating mammals are tasked with accruing adequate energetic resources to survive extended periods of dormancy, where body temperature and/or metabolism drop for extended periods of time, sometimes up to 8-months. Temperate hibernators must then undergo briefs periods of nutrient acquisition, having to forage and put on adequate stores of body fat in the fall, as the hibernation season is characteristic of a fasted state, where bouts of torpor (depressed metabolism and body temperature) are broken up by arousal periods and physiological systems return to a euthermic state for 12-14 hours at a time. Interestingly, during arousal periods, as well as a short time window prior to hibernation entrance (~2 weeks), no intake of food occurs even if abundant and present. The neural mechanisms and systems that hibernators use to control a fall-time feeding switch, as well as maintaining a fasted state upon arousal, are poorly understood.
My PhD research examines brain regions involved in appetite and body weight regulation, and how these regions change circannually. Currently, we are using the ground squirrel as a model to uncover changes in mRNAs and proteins of important regulatory neuropeptides.
My PhD research examines brain regions involved in appetite and body weight regulation, and how these regions change circannually. Currently, we are using the ground squirrel as a model to uncover changes in mRNAs and proteins of important regulatory neuropeptides.
Annual fluctuations in body mass, food intake and metabolic rate of hibernating mammals. From Florant and Healy (2012).
MSc Research
Memorial University of Newfoundland
Supervisor: Dr. Helene Volkoff
Memorial University of Newfoundland
Supervisor: Dr. Helene Volkoff
Uncovering the association between thyroid and appetite in fish
I completed my masters in Newfoundland at Memorial University, using goldfish as a model to study the interaction between the hypothalamus-pituitary-thyroid axis and appetite-regulating neuropeptides in the hypothalamus. In mammals, the thyroid contributes vastly to metabolic expenditure and its role in feeding is clear, with increased activation of this endocrine axis leading to increase energy expenditure and the drive to consume more calories. However, in fish, this system has garnered little attention.
My research uncovered that the thyroid is not as responsive to nutritional status as is seen in mammals. It provides further evidence that fish, unlike mammals, operate their thyroid axis independently of the hypothalamus, possibly as a mechanism to constantly adjust their homeostatic set point in times of unfavorable conditions.
My research uncovered that the thyroid is not as responsive to nutritional status as is seen in mammals. It provides further evidence that fish, unlike mammals, operate their thyroid axis independently of the hypothalamus, possibly as a mechanism to constantly adjust their homeostatic set point in times of unfavorable conditions.
BSc Research
University of Alaska Southeast
Supervisor: Dr. Sherry Tamone
University of Alaska Southeast
Supervisor: Dr. Sherry Tamone
Comparative physiology and endocrinology of crustaceans
At the University of Alaska Southeast in Juneau, Alaska, I studied various physiological and endocrinological aspects of crustaceans - primarily focusing on the Dungeness crab and Northern Alaska spot shrimp.
I researched the effects of laboratory holdings on molting hormones (20-hydroxyecdysone) in Dungeness crab compared to wild-kept crabs - in the presence of temperature and pressure fluctuations. I discovered that wild-kept crabs conform their molting hormone profiles to temperature and pressure, whilst lab-kept crabs showed an inverse relationship.
Using the spot shrimp, I purified and characterized the yolk-protein, vitellin, which was then used to develop an enzyme-linked immunosorbent assay. As spot shrimp are sequential hermaphrodites (transitioning from male to female), this assay allowed us to draw blood samples to assess sex. This will allow fisheries managers to non-lethally assess populations and conserve this declining fishery in southeast Alaska.
I researched the effects of laboratory holdings on molting hormones (20-hydroxyecdysone) in Dungeness crab compared to wild-kept crabs - in the presence of temperature and pressure fluctuations. I discovered that wild-kept crabs conform their molting hormone profiles to temperature and pressure, whilst lab-kept crabs showed an inverse relationship.
Using the spot shrimp, I purified and characterized the yolk-protein, vitellin, which was then used to develop an enzyme-linked immunosorbent assay. As spot shrimp are sequential hermaphrodites (transitioning from male to female), this assay allowed us to draw blood samples to assess sex. This will allow fisheries managers to non-lethally assess populations and conserve this declining fishery in southeast Alaska.