Researchers uncover the process by which gender is determined in the silkworm

May 15, 2014 by Bob Yirka report
An adult female silkmoth. Credit: Munetaka Kawamoto, Laboratory of Insect Genetics and Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo

(Phys.org) —A team of researchers working at the University of Tokyo has at long last uncovered the mysterious mechanism by which gender is determined in the silkworm (and other lepidoterans). In their paper published in the journal Nature, the team describes how they performed in-depth sequencing of RNA transcripts and found differences that account for gender development. Frantisek Marec offers a perspective on the research findings in a News & Views piece in the same issue.

Prior research has shown that lepidoterans have WZ chromosomes, rather than the familiar XY found in humans and other animals. Females have WZ, males ZZ. The W chromosome, the researchers found, doesn't have protein coding genes, and is thus mainly a transposon—genetic material that is able to move around the genome and in many cases cause mutations. There was one exception though, the researchers found, a transcript produced that interacts with piRNA's, which are small RNA's that stop the creation of gonads—this the researchers found, is the feminizing factor. To come to such a conclusion they performed in-depth sequencing of RNA transcripts of both male and female silkworm embryos. In so doing they were able to identify a single transcript expressed in females, but not males. The transcript was identified as a precursor to piRNA which the team has named Fem piRNA.

To ascertain the true nature of the transcript, the team inhibited Fem piRNA in silkworm embryos and found that it was necessary for the development of female silkworm traits. They also found that Fem piRNA played a role in encoding the zinc-finger protein masculinizer, which implied a role in determining male gender traits. W chromosomes, the researchers note, are only transmitted via females, and cannot undergo recombination, with means that mutations are prevented from becoming a fixed trait in future generations.

The work done by the team in Japan represents the first example of gender determining pathways being controlled by piRNA (due either to its presence or absence). Their work also offers some insight into some of the ways that some bacteria influence the gender of their host, and also opens up the possibility of controlling gender in , to allow for more males for example, as they produce more of the silk so prized by us humans.

Explore further: Researchers find chemicals and neurons responsible for turning parental care on and off in mice

More information: Paper: A single female-specific piRNA is the primary determiner of sex in the silkworm, Nature, dx.doi.org/10.1038/nature13315

add to favorites email to friend print save as pdf

Related Stories

Humans have a nose for gender

May 01, 2014

The human body produces chemical cues that communicate gender to members of the opposite sex, according to researchers who report their findings in the Cell Press journal Current Biology on May 1. Whiffs of the ...

Study uncovers why autism is more common in males

Feb 27, 2014

Males are at greater risk for neurodevelopmental disorders, such as autism spectrum disorder (ASD), than females, but the underlying reasons have been unclear. A large cohort study published by Cell Press on February 27th ...

Recommended for you

Research sheds light on what causes cells to divide

Dec 24, 2014

When a rapidly-growing cell divides into two smaller cells, what triggers the split? Is it the size the growing cell eventually reaches? Or is the real trigger the time period over which the cell keeps growing ...

Locking mechanism found for 'scissors' that cut DNA

Dec 24, 2014

Researchers at Johns Hopkins have discovered what keeps an enzyme from becoming overzealous in its clipping of DNA. Since controlled clipping is required for the production of specialized immune system proteins, ...

Scrapie could breach the species barrier

Dec 24, 2014

INRA scientists have shown for the first time that the pathogens responsible for scrapie in small ruminants (prions) have the potential to convert the human prion protein from a healthy state to a pathological ...

Extracting bioactive compounds from marine microalgae

Dec 24, 2014

Microalgae can produce high value health compounds like omega-3s , traditionally sourced from fish. With declining fish stocks, an alternative source is imperative. Published in the Pertanika Journal of Tr ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.