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Single-Sex Prawns Used to Fight Snail-Borne Disease

Single-Sex Prawns Used to Fight Snail-Borne Disease

December 11, 2019

Natural Sciences

Scientific American — Scientists from Ben-Gurion University of the Negev are mobilizing an all-female army to help stymie schistosomiasis, a sometimes-deadly parasitic disease that affects millions of people every year.

Macrobrachium rosenbergii prawns “are voracious predators of parasite-carrying snails” that spread the illness, says Prof. Amir Sagi, a biologist at Ben-Gurion University’s Department of Life Sciences and principal investigator of a new study on the subject.

Prof. Amir Sagi

“The possibility of nonreproducing monosex [prawn] populations, which will not become invasive, opens the path for their use as biocontrol agents.”

The snails that carry the schistosomiasis parasite live in southern and sub-Saharan Africa, parts of Southeast Asia, South America, the Middle East, and some Caribbean islands. Within hours of touching snail-inhabited water, an infected person can suffer symptoms, including fever, cough, abdominal pain, and diarrhea.

The disease can also become chronic and lead to liver and kidney failure, bladder cancer and ectopic pregnancies. The World Health Organization reports that 220.8 million people required preventive treatment for schistosomiasis in 2017.

All-female prawn populations are particularly useful, scientists say. “Female prawns are more docile and less cannibalistic” than males, says Dr. Susanne Sokolow, a disease ecologist and veterinarian at Stanford University, who has worked with Prof. Sagi on related research.

“They grow more evenly, potentially providing a more consistent product for harvest”—meaning local communities could use them for food, as well as snail control.

Like humans, prawns pass on specific chromosomes that determine their offspring’s sex. But unlike humans, female prawns usually have one male and one female chromosome, whereas males have two identical male chromosomes. Laboratory-bred “superfemales,” each with two female chromosomes, can yield only female offspring—making them extremely useful in building a nonbreeding population.

Current methods to produce superfemales are inefficient. By implanting cells from a male’s androgenic gland, Sagi and his colleagues sparked the transformation of superfemales physically into males, the first instance of male M. rosenbergii that completely lack male chromosomes.

These prawns can then easily contribute their female chromosomes to new generations of superfemales. The process was detailed in August in Scientific Reports.

Read more on the Scientific American website>>