5/10/05CSULB Understanding Testicular and Apoptotic Activity in Testicular Regression in American Crows (Corvus brachyrhnchos) By Luwanda k Jenkins

5/10/05CSULB Testis Hypothalamus Pituitary Photoperiod FSH LH GnRH Testosterone Reproduction in American Crows - Testis function is controlled through the HPG axis - Seasonal breeders - The transition from breeding to non-breeding season is marked by a reduction in testicular activity Hypothalamus Pituitary Photoperiod FSH LH GnRH Testosterone Testis

5/10/05CSULB - Non-breeding season is characterized by testicular regression and ultimately testicular function - Breeding season is characterized by an increase in testes mass, seminiferous tubules, and spermatogenesis How does testicular regression occur?

5/10/05CSULB Apoptosis - Stimulated by extracellular and intracellular signals - Characteristics. cell shrinkage. nuclei breakdown. DNA fragments. membrane asymmetry lost. phagocytosed Necrosis - Cell swells and burst - Inflammatory response

5/10/05CSULB Hypothesis: - American crows experience low levels of apoptosis as the breeding season begins and high levels of apoptosis during the non-breeding season, which eventually tapers off to a basal level.

5/10/05CSULB - Fas/FasL and Caspase 3 will both be present. - Both Sertoli (to a lesser extent) and germ cells will be dying.

5/10/05CSULB Methods: -Animals: a) Adult and juvenile male American Crows (n = 60) b) OCVCD and Predator Management Tissue processing - Morphology TUNEL Analysis Immunohistochemistry - Statistical Analysis

5/10/05CSULB Testis Mass Appears to Increase During the Start of Breeding season

5/10/05CSULB Expected Results: - Decrease in testis mass and mean tubule diameter in post-breeding season crows

5/10/05CSULB - Increase in TUNEL labeling in post-breeding season crows - Both Sertoli and germ cells stain TUNEL positive

5/10/05CSULB Conclusion -Testicular regression is caused by an increase in apoptosis -Both Sertoli and Germ cells (spermatogonia and spermatocytes) undergo apoptosis - FasL and Caspase 3 is localized to Sertoli cells - Fas protein and Caspase 3 is localized to germ cells

5/10/05CSULB Significance - Little is know about American crow testicular physiology - American crow population is on a steady incline - American crows have a high susceptibility to the WNV Goal: develop an avian contraceptive

5/10/05CSULB Acknowledgements: - Howard Hughes Medical Institute - Dr. Kelly Young (Research Mentor) - Dr. Robert Cummings (OCVCD) - Mr. Wally Ross (Predator Management) - Coventry Dougherty and Chantelle Moffat-Blue (lab partners) - Dr. Zed Mason (Instructor)