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Microbe sex gets crazy, too

Jan. 3, 2013
Courtesy of the University of Bristol
and World Science staff

Caught in the act! Re­search­ers have watched mat­ing for the first time in the mi­crobes that cause Af­ri­can sleep­ing sick­ness. The trop­i­cal dis­ease is caused by try­panosomes, single-celled par­a­sites that get into the blood of pa­tients.

Scientists from the Uni­vers­ity of Bris­tol, U.K. saw what the try­panosomes were get­ting up to in­side the tset­se flies that car­ry the dis­ease, by us­ing flu­o­res­cent mark­ers to light up the ac­ti­vi­ties.

Mating tryp­ano­somes. (Cour­tesy U. of Bris­tol) 


The mi­cro­scop­ic beasts were seen twirling and gy­rat­ing to­geth­er be­fore join­ing up in­to one hy­brid cell. Their fla­gel­la or “tails” be­came in­ter­twined in the pro­cess. To tell which cell was which, try­panosomes were tagged with dif­fer­ent col­ors, with the re­sult that the hy­brid cells had both col­ors.

Wendy Gib­son, who led the re­search, said: “It’s not only big­ger an­i­mals that have in­tri­cate court­ship – but you need a pow­er­ful mi­cro­scope to see this!”

Sex mat­ters for mi­crobes be­cause it en­ables dif­fer­ent strains to swap genes, lead­ing to new com­bina­t­ions of genes. In the case of dis­ease-caus­ing mi­crobes like the tryp­a­no­some, sex can po­ten­tially lead to a lot of harm­ful genes be­ing com­bined in one strain. The new re­search sug­gest sex isn’t op­tion­al or rare for these mi­crobes, but probably hap­pens eve­ry time two dif­fer­ent try­panosomes find them­selves to­geth­er in the same tset­se fly.

Try­panosomes be­long to a strange group of pro­to­zoa that in­cludes sev­er­al oth­er med­ic­ally im­por­tant par­a­sites such as Leish­ma­nia, Tri­chomonas and Gi­ar­dia. In the past, all these mi­crobes were thought to re­pro­duce just by split­ting in half, but now re­sults show that they al­so use sex to swap genes. The re­search could help sci­en­tists un­der­stand how new strains arise and how char­ac­ter­is­tics such as drug re­sist­ance spread among strains.

The stu­dy, car­ried out in col­la­bora­t­ion with the Uni­vers­ity of Cam­bridge, is pub­lished this week in the jour­nal Cur­rent Bi­ol­o­gy.


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Caught in the act! Researchers have watched mating for the first time in the microbes responsible for African sleeping sickness. This tropical disease is caused by trypanosomes, single-celled parasites that are found in the blood of patients. The researchers at the University of Bristol, U.K. saw what the trypanosomes were getting up to inside the tsetse flies that carry the disease, by using fluorescent markers to light up the activities. The microscopic beasts were seen twirling and gyrating together before joining up into one hybrid cell. Their flagella or “tails” became intertwined in the process. To tell which cell was which, trypanosomes were tagged with different colors, with the result that the hybrid cells had both colors. Wendy Gibson, who led the research, said: “It’s not only bigger animals that have intricate courtship – but you need a powerful microscope to see this!” Sex matters for microbes because it enables genes to be swapped between different strains, leading to new combinations of genes. In the case of disease-causing microbes like the trypanosome, sex can potentially lead to a lot of harmful genes being combined in one strain. These new results suggest that sex is not an optional or rare part of this microbe’s life cycle, but probably happens every time two different trypanosomes find themselves together in the same tsetse fly. Trypanosomes belong to a strange group of protozoa that includes several other medically important parasites such as Leishmania, Trichomonas and Giardia. In the past, all these microbes were thought to reproduce just by splitting in half, but now results show that they also use sex to swap genes between strains. This research helps scientists understand how new strains of disease-causing microbes arise and how characteristics such as drug resistance get spread between different strains. The study, carried out in collaboration with the University of Cambridge, is published this week in the journal Current Biology.