Moselio Schaechter

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March 17, 2011

Fine Reading: Cell Biology of Bacteria

by Elio


Clusters of chemoreceptors of Escherichia coli. The largest
clusters are at the poles. The image shows Tar receptors
visualized by super-high resolution fluorescence microscopy
(PALM). Bar = 1µm. Source.

The publication of an exciting book, Cell Biology of Bacteria, sent me into a reflective frame of mind. You see, I am among the few left from the beginning of the modern era of Bacterial Cell Biology. When I was a graduate student, in the early 1950s, “Bacterial Cytology,” as it was then called, was a subject rife with contentions and contradictions. Soon, however, new studies led to the serious affirmation of the now banal fact that bacteria have recognizable and definable body parts. The curtain was lifted. The nucleoid, the cell membrane, the cell wall, all became respectable entities, amenable to serious study. Just ahead lay the discovery or adapting of advanced techniques. On one hand, suitable cell fractionation methods were developed, on the other hand, microscopic techniques, notably fluorescence microscopy, came of age.

Today, Cell Biology occupies center stage in studies of bacterial physiology and genetics. In my mind, so pervasive is this influence that I was prompted to call ours the Age of Imaging. Now for the book. It is edited by Lucy Shapiro and Rich Losick, both of whom entered this field later in their work, both after having made stellar discoveries in developmental microbiology (in Caulobacter crescentus and Bacillus subtilis, respectively). I’m not about to write a book review, so I will just to say that this 250+ page book covers a wide variety of topics written by major investigators. As you would expect, the book has some stunning images. Pictures here are worth many a kiloword each. One of these merits reproducing here, given that it opens a window into a great future. It shows the distribution of chemoreceptors in Escherichia coli, visualized at a nearly incredible degree of resolution using a novel technique for localizing fluorescence called PALM (for Photoactivated localization microscopy). (Click here for Jennifer Gutierrez's earlier post about this methodology: Exciting Resolution.) Stay tuned for more of such marvels. This is just the beginning.


I couldn't help but remark how similar the figure shown (chemoreceptors in E. coli) is to the images displayed in slide show mode on my iPhone by a NASA App depicting Hubble photos. These links show a couple of example images.

are those spots in the middle in spiral bands? the image is suggestive.

It's surprising and a bit sad how in many areas people still treat bacteria as acellular bags of biochemistry, despite all the stunning (and beautiful) evidence to the contrary. I dream of there someday being a phylogenetically-mindful cell biology course that includes the vast diversity of bacterial cell biology in addition to that of eukaryotes, the latter at last properly sampled with metazoan+yeast cell architectures taught as diverged rather than representative of overall eukaryotic diversity, let alone cell biology overall. Someday...

Our library has this book already, yay! Off to procure it (for right now I'm only about 300% overwhelmed by random projects that have nothing to do with me)...

This is such an exciting topic, Elio! It's interesting to struggle with the Paradigm Warfare in the classroom. Students are accepting that eukaryotic cells are not "bags of enzymes in a colloidal suspension" after learning about the wondrous internal "geography" within a cell.

But the same thing is true within prokaryotes! As I ask them to consider: why are the elements of a respiratory chain in the correct order, and what "holds them" in place? It's just one simple example.

We seem to spend our time as educators teaching a rule, taking a breath, and then showing how the "rule" only applies to a few examples! "Constants aren't; variables don't," as the physics joke goes. It shouldn't be a surprise to students that the internal geography of a prokaryotic cell, revealed by our new technological spelunking, shows such rich structure. Yet students seem surprised (and so do some faculty members).

Still, the paradigm is shifting. STC is part of the advancing Soldiers of the Prokaryotic Revolution!

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