Current Researchers  

Cathy Paterson - Research associate

Cathy is testing possible directs effects of reproduction on aging (i.e., effects independent of nutrient allocation). Reduced reproduction is well known to extend lifespan in many animals. Recently, the mechanism(s) of this life extension has been called into question. To test for a possible direct effect of reproduction on lifespan, I am measuring hemolymph vitellogenin levels in ovariectomized and sham operated females. This will allow us to determine the allocation of proteins (the limiting nutrient in grasshoppers) to reproduction. The direct effects model predicts this allocation will not differ between ovariectomized and sham operated females, even if their lifespans are different. http://www.unf.edu/coas/biology/CPaterson.html

Raime Fronstin - Graduate Student

  Storage thresholds are thought to be important for animals to progress through major life history transitions, but little is known about the physiological manifestations and responses to thresholds. For example, grasshoppers must cumulatively consume a threshold quantity of lettuce to initiate vitellogenesis (Juliano et al. 2004. Ecology). But, the physiological responses to attaining the threshold, and therefore committing to vitellogenesis, are undescribed. Raime is testing whether release of juvenile hormone is sufficient to initiate vitellogenesis, or whether the consumption threshold must also be met to initiate vitellogenesis. In other words, does consuming the threshold and releasing juvenile hormone commit an individual to vitellogenesis, or are other factors required.

Erin Fuller - Undergraduate Student

  Both heat shock and caloric restriction have been shown to increase longevity in fruit flies. This calorie restriction can be started late in life, yet rapidly reduces mortality rate. We have shown that late-onset calorie restriction starting at day 50 (post-reproduction) extends lifespan in lubber grasshoppers. My research is attempting to determine whether the level of expression of Heat Shock Protein-70 (Hsp70, a protein that is produced in response to a variety of stresses) is affected by a caloric restriction diet starting at day 50. Our hypothesis is that Hsp70 plays a role in the rapid reduction in mortality rate upon initiation of late-onset calorie restriction. I have been working in Dr. Hatle's lab since the summer of 2004. I am a Senior undergrad student at UNF, planning to graduate in Spring 2007. I also work full time as an IT Security Specialist at Winn-Dixie Headquarters.

  Imran Jawaid and Colleen Lentz - Undergraduate Students

Imran and Colleen are testing the lifespan of ovariectomized vs. sham opereated female grasshoppers, independent of nutrition. Ovariectomized and sham operated females, when fed ad libitum, consumed very similar amounts of lettuce. We are now determining whether reproductive output and mortality rates differed between the treatments.

Filipe Gusmao and Adel Yazji - Undergraduate Students

Filipe and Adel will test whether the extension in lifespan from ovariectomy is in part due to enhanced thermotolerance and Heat Shock Protein expression.

Dan Hahn - Collaborator at University of Florida Entomology: http://danhahn.ifas.ufl.edu/

With Dan Hahn, we are studying nutritional thresholds of reproduction in flesh flies (Sarcophaga crassipalpus). Hahn's lab has demonstrated that flesh flies offered liver for the first 4 days of adulthood larviposit earlier and larger clutches than flies offered liver only the first 2 days of adulthood. Because levels of hemolymph hexameric storage proteins rise during adulthood, we hypothesize that a critical concentration of these proteins serves as a threshold for the initiation of vitellogenesis. Currently, Hahn's lab is attempting to clone the flesh fly hexamerins and the Hatle lab is attempting to measure levels of ecdysone (the Dipteran gonadotropin) during the reproductive cycle.

Former Researchers

Liza studied the role of hemolymph storage proteins in longevity produced via late-onset calorie restriction. She is now continuing as an undergraduate with plans to become a Physician's Assistant.

Erin tested whether development to adult could be delayed by interfering with insulin signaling by injecting insulin antibody (it could not). She is now applying to Medical Schools.

Sean tested the effects of calorie restriction, late-onset calorie restriction, and intermittent fasting on longevity. We showed that both calorie restriction and late-onset calorie restriction extend lifespan by >50%. He has graduated with a degree in Athletic Training and is now pursing a Master's degree in Physical Therapy at UNF.