High Blastocystis Gene Flow Between Asia and the Americas/Europe

The Internal Transcribed Spacer, a region situated between structural ribosomes, has been useful in tracking genetic differentiation and variation in fungal organisms and yeasts for some time, and now researchers at the University of Mexico (Mexico City) have reported that it can be used for this purpose in Blastocystis as well. Using Blastocystis samples from 47 children who were symptomatic with diarrhea, the researchers analyzed stool samples for other parasites, and also extracted DNA from fecal samples, and then amplified and analyzed Blastocystis sequences.  None of the children selected were found to have bacterial pathogens, and none were identified as carrying any pathogenic parasitic infection other than Blastocystis.  DNA extracted from fecal samples, subtyped Blastocystis isolates using the standard methodology, and almost all infections were found to be of type ST1, ST2, or ST3, with a roughly even distribution between the three subtypes.  Examining existing sequences in Genbank, the researchers found that a high gene flow exists between European and American isolates for ST1 and ST2.  ST3 showed extremely high gene flow between Asia and Africa.  Also, there was a high gene flow for ST3 between Asia and the Americas, and between Asia and Europe.  The full text of the article is available for free at BMC Parasites and Vectors site.

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