Gary Borisy


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The Friday Evening Lecture last week, “The Human Parasite Trichomonas vaginalis: One Cell, Multiple Revelations,” by Patricia Johnson of UCLA covered some delicate territory but tantalized us with several fascinating stories. We were told about a fastidious protozoan that infects only humans and is transmitted only by sex. Its primary habitat is the vagina, from which it gets its name. The creature survives by sucking food out of cells like a leech. It has to be considered quite successful because it infects over 300 million people worldwide and is the most common infectious protozoan.

An audience member wanted to know, “What did the creature live in before there were humans?” Good question. And what about bonobos, our closest living primates? Why don’t they get infected? Another good question. But perhaps the most amazing revelation of the evening was hearing about their fuel cells. They have a curious little structure that makes hydrogen. It is not known why they make it but if we knew how to make it as well and cheaply as they do, it could transform our energy economy. Burning hydrogen is non-polluting as it produces only water as a product. An abundant source of hydrogen could replace coal, oil and natural gas, thus eliminating carbon dioxide emissions. So, the multiple revelations of this one cell give us multiple reasons to try and discover the tricks of Trichomonas.

Trichomonas vaginalis. Photo by Guy Brugerolie, courtesy of micro*scope

Trichomonas vaginalis. Photo by Guy Brugerolie, courtesy of micro*scope

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The MBL’s Friday Evening Lecture series got off to a great start last week with “Building Brain Circuits” by Hollis Cline of Scripps Research Institute who co-directs the MBL Neurobiology course. Advanced imaging technology lets us see directly and in exquisite detail the “bush-like” character of individual nerve cells in living brains. That nerves are bushy has long been known through images of fixed (non-living) preparations. But what was not fully appreciated was that these images represented only snapshots in time–that the bushes were constantly in the process of being remodeled. Holly’s revelatory experiments with live nerve cells showed that the branches were continually growing and dying back–I nearly wrote “pruned” but that would raise the question of who was doing the pruning. And that brings me to the topic of this blog.

The verb “build” in common usage implies a “builder.” The wonder of living things is that objects of great complexity, such as brains, are “built” without a “builder.” How is this possible? Doesn’t construction require blueprints?

An alternative approach is variation and selection. This, of course, is the fundamental principle discovered by Darwin that underlies evolution. Death is as necessary as reproduction for the origin of species. Pruning is as necessary as branching for the shaping of a bush. In my own field of molecular cell biology, the shortening of microtubules is as important as their growth for the shaping of cells. So why should we be surprised that deconstruction is as necessary as construction for the self-building of a brain?

Dual Innervation of the Tadpole Optic Tectum. Image taken by Ed Ruthazer

Dual Innervation of the Tadpole Optic Tectum. Image taken by Ed Ruthazer

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Sunday, June 7, 2009
9 pm EST
The moon was full. The tide was high. And there we were in chest-waders, fanned out across Tahanto Beach in Buzzards Bay looking for the amazing horseshoe crab. Their blood is literally blue, they have eyes that detect polarized light, and they somehow know how to sense tide and moon. But we don’t know how they do it. Alison Leschen, Marine Biologist with the Massachusetts Division of Marine Fisheries was leading us in the second annual horseshoe crab spawning survey. The fossil record tells us that these creatures, resembling nothing so much as Darth Vader’s helmet plus a tail, have remained essentially unchanged for over 400 million years. They have out-survived the dinosaurs and the splitting apart of the supercontinent, Pangaea.

Yet they may not survive us. Visions of hundreds of copulating crabs, the female burrowing into the sand to lay her eggs, the male hanging on to the back of her shell for dear life, danced before me. But the awful truth was that we saw only seven crabs,–two mating pairs and three bachelor males. Where have they all gone? Pollutants have degraded their habitat; biomedical companies harvest their blood to produce a sensitive assay for bacterial endotoxin; and fishermen scoop up what’s left for bait. I don’t begrudge the fisherman their livelihood; and the bacterial assay is the best we have. But isn’t the disappearance of this most extraordinary and hardy creature a warning sign? Can’t we find a way to balance the needs of today with those of generations yet to come, and let the horseshoe crab be a source of awe and inspiration not only to us but to Tomorrow’s Child?

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Max and a horseshoe crab

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