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A budding crescent

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


I'll return to blogging by starting off with a stunningly boring micrograph. Here, you can see a narrow blob, with a blob attached, and a stem below. The scalebar is 2um, so we're really up against the limits of conventional light microscopy here.

*yawn* Not the most flashy micrograph you've ever seen, most likely. But it's still kinda cool, I think: here, you can see bacterial division! This is a stalked bacterium, possibly Caulobacter or something like it -- a major model for bacterial morphogenesis, or shape-formation. At the very bottom of the stalk is a faint thickening resembling a holdfast. The constriction of the cell body is cell division in progress, via budding. The new cell is a flagellated 'swarmer'. Unfortunately, the flagellum that should extrude from the upper (swarmer) cell isn't visible here -- perhaps it's too fine and moves too quickly.

A quick glimpse of the Caulobacter lifestyle can be seen in this review by Hughes et al. 2012 (paywalled). When a swarmer settles, it grows a stalk and soon begins budding to produce swarmers (offspring, essentially). Apparently, once a stalk is formed, the bacterium is attached to the surface for life. If the chosen surface goes awry for whatever reason, it is up to the swarmer cells to detect something is wrong (via presence of leaking DNA from dead colleagues) and not settle down there.


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Were I an organised person, perhaps I'd make one day a week a bacterial day -- while protists are my first obsession, I feel not enough attention is given to bacteria from a morphological and cell biological perspective. Too many people speak of them as chemical. pathogenic or ecological agents, faceless and formless, just blobs with DNA sequences. Most bacteria have been cursed by their size: too small for light microscopy to reveal much, while electron microscopy comes with severe preparation artefacts, meaning one can't really see what a cell does live under EM. You get indirect (while awesome!) suggestions, at best. Luckily, with the development of super-resolution light microscope, the classical 200nm theoretical resolution limit (closer to about half a micron in practice) is finally being crossed, and microscopy can reveal tiny features in still-living bacterial cells! An example of what can be seen with light these days can be seen in this image from Yves Brun's lab. A little bit more detailed than my stalked blob above, eh?

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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