Archive for June, 2009

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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

The sun came out in Woods Hole late this week, shocking many who had grown used to the downpours of the past month. It’s summer! Meanwhile, publications have been streaming out of the MBL labs. Hugh Ducklow, director of the MBL’s Ecosystems Center, co-authored a paper in this month’s Nature Reviews Microbiology, which predicts that a flourishing of bacteria may have a negative impact on polar food webs as ice sheets melt. In the Arctic and Antarctic Oceans, the scientists discovered, bacterial community growth is more dependent on organic carbon produced by phytoplankton than on temperature. As ice melts and more light penetrates the oceans, phytoplankton will flourish and organic carbon will increase. Bacterial populations will likely grow to consume the excess carbon, releasing more of it into the atmosphere as CO2, and leaving less carbon for other marine organisms that rely on it for food. The paper, “Microbial growth in the polar oceans – role of temperature and potential impact of climate change,” is co-authored by David Kirchman and MBL visiting scientist Xosé Anxelu G. Morán.

Sea ice in Antarctica. Photo by Xosé Anxelu G. Morán.

Icebergs in Antarctica. Photo by Xosé Anxelu G. Morán.

Some other recent MBL publications are: “Light-transduction in melanopsin-expressing photoreceptors of amphioxus,” by Maria del Pilar Gomez et al.; “Functional Overlap of Microtubule Assembly Factors in Chromatin-Promoted Spindle Assembly,” by Aaron Groen and other members of the summer collaborative MBL Cell Division Group; “Protein families reflect metabolic diversity of organisms and provide support for functional prediction,” by Margrethe H. Serres and colleagues; “Plasmodium possesses dynein light chain classes that are unique and conserved across species,” co-authored by Andrew G. McArthur; “Schistosoma mansoni P-glycoprotein levels increase in response to praziquantel exposure and correlate with reduced praziquantel susceptibility,” by Shanta Messerli and colleagues; and “Cuttlefish use visual cues to control three-dimensional skin papillae for camouflage,” by Justine Allen and other members of Roger Hanlon’s laboratory.

It’s a good deal chillier at Toolik Field Station, Alaska, where MBL Logan Science Journalism Fellows are delving into the world of field station research, guided by investigators from the MBL Ecosystems Center. Check out the fellows’ blog, with beautiful photos of the Arctic and its midnight sun, at toolikblog.wordpress.com. The fellows will be at Toolik until July 1.

Logan SJP Fellow Jennifer Weiss, from XXX, stands in an aufeis near Toolik Lake. An aufeis forms when an underground stream breaks through the ground and the water freezes when it hits the air. Photo by Emily Stone

Logan SJP Fellow Jennifer Weiss, from the Newark-based Star-Ledger newspaper, stands in an aufeis near Toolik. An aufeis forms when an underground stream breaks through the ground and the water freezes when it hits the air. Photo by Emily Stone

The 09 Logan SJP Fellows at Toolik Lake: Front, from left: Chris Neill (MBL), Jennifer Weiss, Alisa Opar, Kelly Rockwell, Jude Isabella; (L to R, back): Tracey Logan, Charles Michael Ray, Rich McHorney (MBL), Lisa Jarvis, Jane Qiu, Emily Stone. Photo by Dave Gallagher

The 09 Logan SJP Fellows at Toolik Field Station: Front, from left: Chris Neill (MBL), Jennifer Weiss, Alisa Opar, Kelly Rockwell, Jude Isabella; (L to R, back): Tracey Logan, Charles Michael Ray, Rich McHorney (MBL), Lisa Jarvis, Jane Qiu, Emily Stone. Photo by Dave Gallagher

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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

In room 127 of Loeb Laboratory, as the MBL summer courses rapidly pick up speed, Martha Peterson and Herb Luther are zipping around, multi-tasking. They are the MBL staffers who, every summer, make sure the courses have all they need, from duct tape to high-end microscopes. But this year is different. Come September, Loeb will be gutted and rebuilt over the winter into a state-of-the-art training facility. That makes this the last season of courses in the old Loeb, where faculty and students have come and gone (and often returned) every summer since 1970.

The packing has already begun. Among the first items sent to storage were the framed class photos that always hung proudly outside of the course labs. These photo galleries are amazing records of generation upon generation of MBL students and faculty, some stretching back to the early 1900s, all of them sparkling with scientific “superstars.” Taking the annual class photo and adding it to the course’s gallery is so much a part of the MBL tradition, that people are really missing the photos since they were taken down for safekeeping.

The Microbial Diversity folks missed their original class photos so much, they pinned up copies of the photos in their gallery. (Photo by Diana Kenney)

The Microbial Diversity folks missed their original class photos so much, they pinned up copies of them in their lab gallery. (Photo by Diana Kenney)

The new Loeb is scheduled to open next June, before most of the summer courses begin. There is a lot to look forward to, including upgraded lab space and modern support facilities. But not everything will be new: class photos will still be displayed, reminding students of their MBL “ancestors.” “I will see that the photos go back into the new building!” Luther promises.

The Microbial Diversity folks missed their original class photos so much, they pinned up copies of them in their lab gallery. (Photo by Diana Kenney)