Gender-bender

Gender-bender prawns produce higher yields

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    By Sarah Carnvek
     
     
    In most of the freshwater prawn hatcheries in Vietnam, farmers separate the male and female crustaceans by hand because males are more plentiful and meaty. Thanks to an Israeli research team, there's now a new hands-off technology to increase yields and profitability for local farmers.
     
    Prof. Amir Sagi from Ben-Gurion University of the Negev (BGU) developed an innovative advanced gene-silencing biotechnology for aquaculture. The method successfully changes the sex of prawns and helps boost fast-growing all-male populations.
     
    “This is the first time that the aquaculture industry will be able to use advanced gene silencing to increase yields,” says Sagi. “Since the males are faster growers, this discovery could help local farmers increase their income.”
     

    These are male prawns, which are meatier and more abundant than female ones.
    http://www.flickr.com/photos/75061343@N02/8460493195/in/photostream
     
    Every year, the UN's Food and Agriculture Organization reports a rise in seafood consumption. Prawns and shrimp are among the most popular types of shellfish.
                            
    The Israeli technology was patented and licensed through BGN Technologies, BGU's technology transfer company, to the Tiran Group, an Israeli shipping company with aquaculture farms in China. Tiran recently signed an agreement with Vietnam’s Green Advances to progress aquaculture in Vietnam using the innovative technology.
     
    The signing ceremony took place in Can Tho, the largest city in the Mekong Delta, in the presence of the governors of the delta, Zafrir Asaf, the Israeli commercial attaché to Vietnam, Tiran Group Managing Partner Haim Avioz,and Green Advance Chairman Phan Minh Tuan.
     
    Sustainable technology to feed a growing population
     
    Gene-silencing technology can be used to protect animals from diseases and to develop new crop varieties. Sagi, incumbent of the Lily and Sidney Oelbaum Chair in Applied Biochemistry at BGU and president of the International Society for Invertebrate Reproduction and Development, was the first to successfully use this technology to revolutionize prawn aquaculture.
     
    Sagi led a team of researchers to produce a cutting-edge biotechnological tool for crustacean gender reversal and mono-sex progeny production.
     
    Knowing that sexual differentiation in crustaceans is regulated by the androgenic gland, and removal of that gland from immature males results in gender reversal, the Israeli scientists found that sex-reversed (“neo-female”) animals are capable of mating with normal specimens to produce all-male offspring.
     
    "We're crossing two males and the progeny are all male," explains Sagi. "This kind of technology allows farmers in [Asia] to increase their income by approximately 60 percent. This is the first case in the whole field of aquaculture that people are using by this technology in order to get the desirable results."
     
    The technology not only improves productivity but requires no considerable infrastructure investment, either.
     
    “The technology is sustainable since it doesn’t use any chemicals or hormones and does not create genetically modified organisms [GMO]. “This is made possible through the unique monosex culture of prawns, which we can obtain by using our original discovery of an insulin-like androgenic hormone that influences the sex of these prawns."
     
    Doron Krakow, executive vice president of American Associates, Ben-Gurion University of the Negev, added that Sagi has already pioneered several previous techniques to increase rice and crustacean output in countries such as Vietnam.
     
    “As the world faces a challenging population growth and decreasing resources, [this] work provides sustainable solutions for developing nations,” Krakow said.
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    Male prawns Male prawns Copyright: Photographs © Ben-Gurion University of the Negev
     
     
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