Navigation Links
Male or female? In flies, some cells can't tell

An experienced fruit fly researcher can tell at a glance whether the fly she is observing is male or female; a distinct pigmentation pattern on a fly's body (a type of bristle found only on the legs of males) and differences in the genitalia are dead giveaways. But most of the fly's body parts look identical in males and females, and until now, scientists had no idea whether "maleness" or "femaleness" extended to all of the insect's cells and tissues. In a study publishing today in the online, open access journal PLoS Biology, researchers at the Janelia Farm Research Campus of the Howard Hughes Medical Institute find that most cells in flies' bodies are identical, regardless of whether they are in a male or a female.

This is because the influence of sex-determining genes is restricted to specific tissues, says Bruce Baker, a group leader who conducted the research with colleagues Carmen Robinett, Alex Vaughan, and Jon Michael Knapp. Baker has been studying the genetics of fruit fly sex for 30 years. By the early 1980s, it was known that a cascade of genes determines how tissues and organs develop in a sex-specific manner. In this bureaucratic chain of command, each gene tells the next one how and when to act. The doublesex gene, the master gene that determines sexual characteristics, is the last gene in the cascade. In flies, females express one form of doublesex, and males another. This gene is viewed as a master switch that tells female cells to create female sexual characteristics and male cells to make male ones. Until now, fly geneticists clung to the notion that the male version of doublesex was switched on in every cell of male flies, while the female version was present in every cell in female flies.

Prompted by other labs reporting that doublesex is turned on only in small areas in the fly embryo and only in specific parts of the brain, Robinett and her colleagues employed a genetic engineering technique to detect doublesex expression in the cells of developing flies. The technique attaches a reporter gene to doublesex that makes cells expressing the gene glow green. Tracking doublesex then becomes as easy as watching for green spots in fly embryos, larvae, and adults. With this approach, Baker's group found that during fly development, doublesex switches on and off at different times and in different tissues. As expected, they saw doublesex protein in the genitalia and in other body parts that display differences between males and females. But in body parts where there are not overt differences between males and females, they found that doublesex was expressed only in certain cells and not expressed in many other types of cells. "It's a simple observational study with profound implications," Baker says. This study demonstrates that only a subset of cells is likely to know whether they are male or female. Robinett and her colleagues found that male and female fruit flies are really a mixture of cells that are sex-specific and cells that are sexless. Many of the fly's cells never turn on the doublesex gene. So while, some cells "know" their sex and take on sex-appropriate characteristics during development, those that do not express doublesex remain identical in males and females.

Because doublesex or analogous genes are present in myriad organisms, including humans, this theme may apply to more than fruit flies. "It may be broadly true that males and females are made up of a mosaic of cells that know their sex and cells that don't," Baker says. This could prompt other researchers to check for similar doublesex patterns in other model organisms such as roundworms, zebrafish, and mice. If similar findings emerge, it could shake up the entire notion of sex differences in the animal kingdom. And if the finding applies to humans a big "if" at this point the implications could be even more significant. "If it applies to people, it's certainly going to change our sociological view of what we think of as maleness and femaleness."


Contact: Jennifer Michalowski
Public Library of Science

Related biology news :

1. How do you know whether you are male or female?
2. Broccoli component limits breast cancer stem cells, U-M study finds
3. Scripps Research team provides groundbreaking new understanding of stem cells
4. California funds UCI basic research on stem cells
5. Lensless imaging of whole biological cells with soft X-rays
6. Innovalight Establishes New Record With Silicon Ink Solar Cells
7. Gene silencing may be responsible for induced pluripotent stem cells limitations
8. Production of biofuels could benefit by controlling the types of cells that develop in plants
9. Chloride channels render nerve cells more excitable
10. Scientists sever molecular signals that prolific parasite uses to puppeteer cells
11. Carbon nanotubes boost cancer-fighting cells
Post Your Comments:
(Date:11/17/2015)... Mass. , Nov. 17, 2015 Pressure ... leader in the development and sale of broadly enabling, ... worldwide life sciences industry, today announced it has received ... its $5 million Private Placement (the "Offering"), increasing the ... $4,025,000.  One or more additional closings are expected in ...
(Date:11/12/2015)...   Growing need for low-cost, easy to ... paving the way for use of biochemical sensors ... in clinical, agricultural, environmental, food and defense applications. ... medical applications, however, their adoption is increasing in ... emphasis on improving product quality and growing need ...
(Date:11/9/2015)... DUBLIN , Nov. 09, 2015 /PRNewswire/ ... announced the addition of the "Global ... to their offering. --> ... "Global Law Enforcement Biometrics Market 2015-2019" ... Research and Markets ( ) ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... N.C. , Nov. 24, 2015  Clintrax Global, Inc., a ... North Carolina , today announced that the company has set ... represented a 391% quarter on quarter growth posted for Q3 of ... and Mexico , with the establishment ... in December 2015. --> United Kingdom ...
(Date:11/24/2015)... PHILADELPIA, PA (PRWEB) , ... November 24, 2015 , ... ... young entrepreneurs at competitive events in five states to develop and pitch their BIG ... student projects from each state are competing for votes to win the title of ...
(Date:11/24/2015)... SHPG ) announced today that Jeff Poulton , Chief ... Annual Healthcare Conference in New York City , ... p.m. GMT). --> SHPG ) announced today that ... Jaffray 27 th Annual Healthcare Conference in New ... 8:30 a.m. EST (1:30 p.m. GMT). --> Shire plc ...
(Date:11/24/2015)... , Nov. 24, 2015  Tikcro Technologies Ltd. (OTCQB: TIKRF) today announced ... 29, 2015 at 11:00 a.m. Israel time, at ... 98 Yigal Allon Street, 36 th Floor, Tel Aviv, ... Eric Paneth and Izhak Tamir to the Board of ... as external directors; , approval of an amendment to certain terms ...
Breaking Biology Technology: