Saturday, January 10, 2009

Big Nuts

I thought that the people who read my blog (all two of you) might like to see an example of what it is that I study. My lab focuses on sex determination and gonad organogenesis - or rather, how the decision is made to become male or female, how the organism's cells remember this decision, and how the process plays out. Since humans become male or female depending on whether their gonad develops as a testis or an ovary, we study the particular cellular decisions that must be made for the gonad to commit to a testicular or ovarian fate.

Sometimes the signals get mixed and the decision isn't clear, and as a result you end up with a hermaphrodite, or intersex organism - having both male and female parts. Other times the right signal is masked or lost entirely such that the opposite decision is made and sex reversal occurs.

Inside the gonad (both testis and ovary) special cells, called germ cells, give rise to either sperm or oocytes which are responsible for generating the next generation. These cells represent the immortal line, and through them we can all be traced back to the very beginnings of cellular life on this planet. My focus is on these germ cells, and how they decide to behave accordingly depending on which kind of gonad they end up in.

Particularly I study a mouse that has a mutation that causes germ cells to do something considered very bad in humans - turn into cancer! Germ cells are so special, and powerful, that they are set aside at very early stages during development - so early that there is no gonad for them to live in yet. So they wait for the embryo to develop further and begin to migrate to the inside, up through the hidgut and finally to the site of the emerging gonadal tissue just in the nick of time.

In my mutant males, the germ cells are pretty sick before they get to the gonad and only a few make it. Those that make it to a testis end up transforming a few days later and turning into early cancer cells. By birth the mutant testis is already sick with these growing cells, forming an early tumor. Two weeks after birth the testes look monstrous - even the name for this kind of tumor, teratoma, actually comes from the Greek meaning 'monster'. Here's a picture of normal mouse testes and then a pair of testes from my mutants:

Overall my goal is to study germ cells and learn about how this gene affects their development. One of my sub-goals is to figure out how and why this particular mutation causes these kinds of tumors at this particular point during development.

Cool, huh?

No comments: