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Cyanobacteria meet again

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American



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A free-living cyanobacterium (above) lies next to its brethren from a distant past, now a chloroplast coiled up and trapped (for good) within a eukaryotic cell (bottom). The chloroplast still has remnants of the cyanobacterial genome, with a greatly reduced gene set. Both bacterial inner and outer membranes have also been retained -- which is how both plastids and mitochondria usually have a double membrane. The most bacterial-like of the plastids belong to Glaucophytes, a small group of deep-branching algae. These plastids have retained the bacterial peptidoglycan (wall material) layer, between the two membranes. This, along with their vibrant blue-green colour, earns them a distinct name: cyanelles.

Pretty much every photosynthetic eukaryote you see shares one single common origin of plastid endosymbiosis, with the exception of a testate amoeba -- Paulinella chromatophora, which has one or two recently reduced cyanobacteria ('cyanelles', again) of a separate origin. There is a relatively large interest (reads: a couple labs) in Paulinella in hopes that studying it will reveal something about how plastid endosymbiosis works, as well as some insights to how the other (main) symbiosis event happened. Eukaryotes have thus domesticated cyanobacteria on at least two separate occasions, and seem to be doing fairly well with their stolen agriculture industry.

About Psi Wavefunction

I first encountered the wonders of the protist realm back in childhood, when a murky droplet of pond scum was revealed by the microscope to entail an alien world in its own right. It took another decade to discover there was a field and a community dedicated to these organisms, and I bade farewell to the study of more familiar big things. As a kid I was also fascinated by tales of exploration of the New World, as well as those of fantasy worlds. I was then sad that the age of surveying new landmasses on earth was over, and that human extraterrestrial adventures are unlikely to happen within our lifetimes. It seemed everything was discovered already. But that could hardly be further from the truth -- all that is necessary to begin one's own Age of Exploration is a new approach or perspective, and a healthy does of imagination. Since reality has conjured far more than the human mind alone ever could, science yields a way to write stories much wilder than fiction. All one needs to access the alien world of microbes around (and inside) them is a shift of scale by simple glass sphere.
I'm currently finishing up my undergraduate degree in Vancouver and in transition career-wise, hopefully to end up in graduate school soon. I was born in Russia (and speak the language) and spent most of my life in US and Canada. In addition to protists, I'm fascinated by evolution, including that of culture and languages, diversity and biology of cells and how they self-organise, linguistics and anthropology, particularly of the less talked-about cultures, sociology of science and plenty of totally random things that snag my attention.
Banner image was kindly post-processed and enhanced by my friend: an accomplished comic artist who goes by Achiru.

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