Developmental genetics

Key to our understanding of growth regulation in Drosophila would be discovering a ligand that could regulate steroid synthesis. Activins are involved in regulating steroid hormone release in vertebrates. In invertebrates, they most likely function to keep ecdysone levels low to allow the larvae more time to achieve critical weight in order to initiate the metamorphic process. TGF-B(Transforming Growth Factor Beta) is a family of cytokine growth factors. We find that two members of the TGF-B signaling pathway Drosophila Activin (dACT) and Activin-like ligand Dawdle (DAW) signal through the type I receptor Baboon (BABO) and the type II receptor PUNT to primarily activate the transcription factor dSMAD2 and MAD to a lesser extent. One transcription factor brinker (brk) appears to be central to dACT signaling.

The thymus provides a unique microenvironment that facilitates T lymphocytes differentiation and maturation. However, the thymus atrophies after puberty which leads to an overall expression of metabolism gene pathways and low gene expression of certain peroxide scavenger enzymes such as catalase in thymic stromal compartments. From this data, we postulate that thymic stromal cells are highly susceptible to oxidative damage. We utilized a transgenic mice model overexpressing human catalase targeted to the mitochondria (mCat) to test our hypothesis that gerater oxidative protection should lower the degree of thymus atrophy. Our experiment focused on a direct comparison of organ weights (thymus, kidney, lymph nodes, spleen and heart), cellularity and histology between transgenic and wildtype mice. We found that mCat had selective increases in thymus size.