Transcriptomic Analysis of Blastocystis ST1!

BLASTing Breaking News!

Probably to support their genomic data, researchers in Andrew Roger's group in Canada have performed transcriptomic analysis of the Nand II strain, which belongs to Blastocystis sp. ST1.

Running from April 29 to May 2 is the SMBE (Society for Molecular Biology and Evolution) satellite meeting on Eukaryotic-Omics; the abstract booklet can be downloaded here. And fellow tweeps, don't let yourselves down by not following #SMBEeuks!

Watching #SMBEeuks tweets ticking in from @druvus @dr_bik and @ctitusbrown feels like attending the actual conference - without the jet lag!
— Chr. Rune Stensvold (@Eukaryotes) April 29, 2013

Until now, we've only known of one complete Blastocystis nuclear genome, namely that of ST7. Now, the release of the ST1 genome may be imminent! In any case, Roger's group have used their transcriptomic data to compare the protein content in ST1 with that in ST7, and it appears from their conference abstract that "the genes encoded by the Nand II strain (ST1) are surprisingly distantly related to ST7 orthologues, sharing on average ~50% identity at the protein level." And more: "Preliminary analyses allowed us to detect ~1000 genes in ST1 that have no homologue in Blastocystis sp. ST7". This means that the extreme genetic diversity that we see across the SSU ribosomal RNA genes is reflected and may be even more pronounced at nuclear genome level.

The group also studied genes acquired by lateral gene transfer (LGT; see previous post for more on LGT, also known as horizontal gene transfer), and what they basically found was that ST1 appears to have acquired bacterial genes related mainly to metabolism, while genes acquired from eukaryotes code for proteins related to cellular processes and signaling mechanisms.

Finally, they have discovered genes obtained by LGT that has had importance for Blastocystis' adaptation to parasitism; among these genes that enable resistance to host immune responses.

Roger's group is based at the Dept. of Biochemistry and Molecular Biology, Dalhouise University, Halifax, Nova Scotia in Canada.

A Penny For Your Thoughts

So, what should we do about Blastocystis? What do we want to know?

I believe the imminent answer to the latter question is easy: We want to know whether it’s pathogenic, whether we should treat it and how. But I also think that there are many other interesting aspects of Blastocystis which are also of broad interest to the general public, namely: How about the many cases of asymptomatic Blastocystis carriage? What does Blastocystis do in our guts? Could it have any potentially beneficial impact on our health?

Given the fact that Blastocystis has not been implicated in any outbreaks (admittedly: I guess that no one actually ever looked for Blastocystis in outbreak investigations... except for me!), I reckon that the chance of it being involved in acute diarrhoea is small. So, in that respect it's very different from the other intestinal protists such as Giardia, Cryptosporidium, Cyclospora, microsporidia, even Entamoeba histolytica. It's actually more reminiscent of helminth infections, which are are often chronic, and when light hardly give rise to symptoms (depending on species that is!).So I'm more thinking along the lines of co-evolution, adaptation, etc.

Maybe future research will call for a shift in paradigm, but until then I think that we should do what we already can, just at a larger scale and see where it takes us, namely: