New thinking on regulation of sex chromosomes in fruit flies

Sep 19, 2011

Fruit flies have been indispensible to our understanding of genetics and biological processes in all animals, including humans. Yet, despite being one of the most studied of animals, scientists are still finding the fruit fly to be capable of surprises, as evidenced by new research at the University of Rochester.

The latest revelation has to do with the activity of the in male fruit flies. It was widely accepted that all X chromosomes in male fruit flies showed an increased level of activity. It was also believed that, in the absence of increased activity, the cell would die. But biologists at the University got some unexpected results when they studied chromosomal behavior in fruit flies.

The findings, by the lab of Associate Professor Daven Presgraves, have been published in the journal .

While chromosomes in most animals come in pairs, that is not the case with all sex chromosomes. Males, typically being the ones to determine the gender of , carry both the X and Y chromosomes, compared to the female, which carries two X chromosomes. Since the carry for traits that go beyond gender determination, a process—called dosage compensation—evolved to ensure that the X chromosomes in males and females are expressed at the same level.

Dosage compensation occurs differently from one species to the next. In male (Drosophila), the expression—or activity—of genes on most of the single X chromosomes is doubled to match the expression of the two X chromosomes in female cells. Scientists have believed that the process of dosage compensation occurs in all cells of the male fruit fly. But University biologists have discovered that is not the case with the germ (reproductive) cells in the testes.

A complex of proteins called the dosage compensation complex is responsible for upregulating gene expression in somatic (non-reproductive) cells. "That complex doesn't exist in germ cells, so it was assumed that dosage compensation occurred in those cells by some other mechanism," said lead author Colin Meiklejohn, "We showed there is no upregulation of X chromosomes in the testes of flies."

Scientists have assumed that dosage compensation is needed for any male cell to survive, said Meiklejohn. It's not clear why there are no negative effects in the male sex cells, but Meiklejohn said that's a question University researchers will look at next.

Explore further: Improving the productivity of tropical potato cultivation

Related Stories

X chromosome exposed

May 29, 2008

Researchers from the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, and the EMBL-European Bioinformatics Institute (EMBL-EBI) in Hinxton, UK, have revealed new insights into how sex chromosomes are regulated. ...

Sex and the single chromosome

Nov 26, 2010

Is there value to sex? For higher organisms, absolutely. Animals, plants and fungi that reproduce only by cloning are scarce as hen's teeth, suggesting the gene shuffling of sex pays handsome dividends.

The story of X -- evolution of a sex chromosome

Apr 16, 2009

(PhysOrg.com) -- Move over, Y chromosome - it's time X got some attention. In the first evolutionary study of the chromosome associated with being female, University of California, Berkeley, biologist Doris ...

Recommended for you

Building better soybeans for a hot, dry, hungry world

6 hours ago

(Phys.org) —A new study shows that soybean plants can be redesigned to increase crop yields while requiring less water and helping to offset greenhouse gas warming. The study is the first to demonstrate ...

Gene removal could have implications beyond plant science

6 hours ago

(Phys.org) —For thousands of years humans have been tinkering with plant genetics, even when they didn't realize that is what they were doing, in an effort to make stronger, healthier crops that endured climates better, ...

Chrono, the last piece of the circadian clock puzzle?

20 hours ago

All organisms, from mammals to fungi, have daily cycles controlled by a tightly regulated internal clock, called the circadian clock. The whole-body circadian clock, influenced by the exposure to light, dictates the wake-sleep ...

User comments : 0

More news stories

Revealing camouflaged bacteria

A research team at the Biozentrum of the University of Basel has discovered an protein family that plays a central role in the fight against the bacterial pathogen Salmonella within the cells. The so cal ...

EU must take urgent action on invasive species

The EU must take urgent action to halt the spread of invasive species that are threatening native plants and animals across Europe, according to a scientist from Queen's University Belfast.

Progress in the fight against quantum dissipation

(Phys.org) —Scientists at Yale have confirmed a 50-year-old, previously untested theoretical prediction in physics and improved the energy storage time of a quantum switch by several orders of magnitude. ...