Dan Frank
M. S. Student

B. S. in Animal Science from the
University of MD at College Park

Originally from Long Island, New York

Research:

I am interested in studying the developmental effects of the sex steroid hormones testosterone and estradiol on all stages of embryonic development. Research conducted over the past several decades has shown that sexual differentiation is an irreversible forward process that begins with fertilization. This process occurs in series, and each stage of development is responsible for the next. The system is hormonally driven and is sensitive to hormone levels and timing of exposure.

An animal’s phenotype results from intimate interactions between the genotype and the environment where that genotype is expressed. Avian females can influence offsprings’ behavior through a variety of non-genetic maternal investments made prior to embryonic development. Maternally-derived testosterone investment in eggs has been associated with varying degrees of aggression in offspring. The testosterone is deposited into the egg yolk during vitellogenesis. Behavioral differentiation occurs late in embryonic development in response to embryonic steroidogenesis, and testosterone levels play a role in aggression. However it remains unclear how maternally- derived testosterone affects behavior.

The focus of my research is to evaluate the mechanisms by which maternally- derived testosterone affects the behaviors of their offspring. I have chosen the domestic chicken, Gallus domesticus, as a model animal to study. Since embryonic steriodogenesis begins at about day 3.5 of the 22 day incubation period, I will investigate the effects of yolk testosterone on development from ovaposition until the emergence of the indifferent steroidogenic primitive gonad. The primitive gonad is formed from primordial germ cells. These cells are differentiated from pluripotent cells of the epiblast and migrate to colonize the genital ridge. I believe that maternal testosterone elicits its effects at this early stage of development and sets the course for the cascade of events that lead to permanent offspring behaviors.

Hobbies:
In my free time I enjoy working on my home, engaging in political discussions, hiking, skiing, and spending quality time with my family.