Accessible Research: Y chromosome sequence moves around in a fly

What better time to start making science accessible (and interesting) to the general public than now? Comments on whether there is too much or too little substance here will be much appreciated!

For my first attempt, here's a brief introduction to some work done by a grad student I met a couple years ago, in collaboration with her PhD advisors. She now has her PhD and is working as a postdoctoral fellow. Additional congratulations to her for being a successful mommy scientist!

This work can be found here, in the journal of Molecular Biology and Evolution.

Translocation of Y-Linked Genes to the Dot Chromosome in Drosophila pseudoobscura

Amanda M. Larracuente *1, Mohamed A. F. Noor 2 and Andrew G. Clark 1
1 Department of Molecular Biology and Genetics, Cornell University
2 Biology Department, Duke University

Drosophila pseudoobscura is a tiny fruit fly. Why is it interesting to study fruit flies? Many reasons! Fruit flies are small and easy to raise (so you can look at many of them), have a very short generation time (so there are lots of changes between species), they have large chromosomes (that are easy to see and manipulate), and there are many recently-diverged species (so we can study how new species appear).

Fruit flies have 4 pairs of autosomes (non-sex chromosomes) and a pair of sex chromosomes (X and Y), along with an extra, very tiny, dot chromosome. (You can see them on this page.) In order for cells to divide properly to form sperm and eggs, each pair, including the X and Y, must partner up and segregate. But, how the X and Y pair in this little fruit fly is still not well understood.

This fruit fly is unique among those studied so far because many of the genes on its Y chromosome moved to the tiny dot chromosome. This allows scientists a useful opportunity to study how the X and Y pair. The three researchers listed above not only identified this movement, but also figured out that there is a stretch of DNA sequence, called the intergenic spacer region (IGS), found on both the X chromosome and the region of the Y that moved, meaning it could likely be the sequence that allows X and Y to pair.

Understanding how chromosomes pair is useful for understanding genetic disease where chromosome pairing goes wrong. For example, in Turner syndrome, a human female has only one copy of the X chromosome instead of two (occurs in 1 out of 2000 live births). Women with Turner syndrome may experience a range of symptoms from a wide and webbed neck to fertility problems. Although it can be treated, there is not yet a known prevention of the syndrome. Thus, research on a tiny little fruit fly may one day lead to a prevention of Turner syndrome.