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MISSION DISPATCH 9 August 25, 2007 Mark Schrope - @SEA Correspondent aboard the R/V SEWARD JOHNSON Location: Off Little San Salvador 
Sea Trials
Three thousand feet down in saltwater is an incredibly punishing environment for machinery, a lesson we were reminded of today. This morning's scheduled dive had to be put on hold after routine pre-dive checks revealed a problem with the sub's thrusters. The sub crew worked diligently throughout the day and by late afternoon all was once again set for safe diving, so only one dive was ultimately lost. For today's only dive, Tammy Frank was in the sphere with Harbor Branch sub pilot Craig Caddigan further exploring the muddy expanse at about 2,500 feet. The first task was to collect Tammy's two traps deployed yesterday, which to her surprise were a hundred feet apart, thought they had bee placed together. Something must have picked up one of the traps and carried it," she says, "because while things out here do seem to follow different laws of physics sometimes, to the best of my knowledge things do not roll uphill." During later exploration they were able to observe a number of shrimps and other crustaceans, but most couldn't be collected because soft, muddy bottoms make collections difficult. "As soon as you get close, everything disappears in a cloud of sediment," says Tammy. 
Fun With Worms We had a full slate of dive and snorkel trips again. One of the more notable samples collected was a translucent alciopid worm, which has disproportionately large, fluorescent green eyes. Misha Matz has also discovered that when prodded, the worm releases a fluorescent ink, the second time he has seen such a phenomenon in a worm. Misha and his graduate student, Marguerite Hunt have collected more than enough fluorescent samples to keep them busy with genetic and other analyses for months if not years to come. Misha says the fire worm collected yesterday, with its red and green fluorescence (see photo from Day 8) is one of the most interesting finds of the trip for him because it will allow him to focus on both the ecology and potential biotechnological use of fluorescence, his two key interests. How Do You Tell a Fish to Back Off? Even in shallow depths, all colors but blue are quickly absorbed by water. Animals can get darker, but they don't have the option open to land animals of using bright colors to warn, "don't eat me or I'll hurt you". Depending on the visible blue light, getting darker is about the only option open in the ocean. The fire worm, for instance, has a somewhat darker red color than other worms, but the difference is slight and wouldn't seem enough to offer a warning. Fluorescence, however, offers a possible means around this blue light challenge because it involves absorbing blue light and reemitting it as a different color—typically green or red. The question is whether most animals can detect these colors, and if so, whether they do in fact interpret the fluorescent colors as messages. 
Ecologically the worm is an ideal focus because, like other poisonous organisms, it is likely to have some means of announcing to warn potential predators that they should stay away. Clearly the fire worm has this capability. "It crawls around in broad daylight even though it's a big, fat, juicy worm and it doesn't care about all the fish around," says Misha, "my argument is that this is fluorescence working." He'll now be working to prove that argument. Testing whether shallow organisms are using fluorescence should be straightforward. Misha plans to do experiments such as using lighting to block or enhance the fire worms' fluorescence to learn if fish do react to it. But fire worms are shallow species. Proving whether fluorescence is used in the deep sea will be quite a bit more challenging, in part because access to the deep sea and animals from there is so much more limited. "I'm afraid the deep sea will remain an area of speculation and extrapolation for a long time," says Misha. There are a number of possible explanations for deep-sea fluorescence, assuming that the phenomenon is not an unused physiological by-product. One is that the small amounts of light that make it into the deep, which Edie Widder and her colleagues have been measuring, is intense enough to well-adapted eyes to cause detectable fluorescence. Another possibility is that the blue bioluminescent light created chemically by so many ocean organisms is enough to excite fluorescence. "This seems like quite a crazy idea," says Misha, "but I like to keep it in mind." The final option is that fluorescence evolved in shallow water species that migrated to the deep but no longer have use for their fluorescence. As Misha and his collaborators complete genetic studies of the fluorescent compounds in the various animals collected, they'll be looking for clues as to how and where the fluorescence evolved to begin to answer some of the many remaining questions. Seeing Red Can Be a Good Thing  The fire worm, along with several other samples collected during this cruise, will also be a good focus for Misha's work aimed at isolating new fluorescent proteins, which are used ubiquitously in biomedical studies. Such work involves adding the genes that encode for a particular fluorescent compound's production as a "tag" in a longer sequence of genes. For instance, researchers interested in the role a particular protein plays in transforming normal cells into cancer cells might genetically alter mice so that the tag is produced in conjunction with the otherwise effectively invisible protein of interest. Doing so would make that protein glow, making its activity easy for researchers to observe and track as a tumor grows in the mice. The vast majority of the fluorescent tags in use today are green, the first of which was isolated from a jellyfish. Red tags are available, and in fact the most common one was discovered by Misha in a mushroom anemone in 1999. But red is much less common, meaning that samples with red fluorescence are more likely to be something new, and new fluorescent proteins mean new experimental opportunities. Existing tags have several limitations—for instance they won't work for certain types of experiments with the exterior membranes of cells—that new ones might allow researchers to work around. Misha is hoping that compounds from the red fluorescence he found in the fire worm, a jellyfish, and a fish will one day offer just such options. The End Is Near The call has been made. We'll be doing all remaining submersible dives here at Little San Salvador and then making the more than 20-hour steam to Freeport all in one shot. There are two submersible dives scheduled, and as soon as those are completed we'll be on our way. 
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