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Antarc Tic 11 OFTHE IIUNITED U STATES antarc tic 11 OFTHE IIUNITED U STATES December 1985 National Science Foundation Volume XX—Number 4 How Weddell seals defy In this issue... the bends How Weddell seals defy the bends ...................... 1 Weddell seals (Leptonychotes weddelli) by humans, pressure within the lungs Sea-ice microorganism aids can dive to depths greater than 500 meters increases, and more gas is dissolved in the biotechnological research ....... 3 and remain submerged for more than an bodys fluids. As a diver ascends, inert Optics of snow and sky........... 3 hour. They can ascend rapidly without gases, like nitrogen, must be eliminated, William J . Merrell appointed experiencing decompression sickness or or nitrogen bubbles form in the blood and Assistant Director for AAEO.... 6 nitrogen narcosis, two hazards commonly body tissues, which have become super- New staff at DPP ................ 6 faced by human divers. During deep dives saturated with nitrogen. This painful Surface balance in ice drainage systems of Antarctica .......... 6 Ohio State University acquires Byrd papers ............... 14 Geology of the northern Chilean Weddell seals rest on the sea ice near Ross Island. Consummate divers, Weddell seals are Canals: Hero cruise 84-6 ...... 16 able to dive meters or more and remain submerged for more than hour. Until recently, 500 1 U.S. criminal jurisdiction available data only suggested how these seals survive such great depths over long time periods, but with the aid of computers, scientists, supported by the National Science Founda- extended to Antarctica ........ 18 tion, have begun to unravel this mystery. Sailing directions for Antarctica updated .................... 18 NSF photo by Ann Hawthorne. Antarctic research proposal deadline .................... 18 Sea ice atlas available............ 19 Translations available........... 20 Foundation awards of funds for antarctic projects, 1 July to 30 September 1985 ........... 20 I Weather at U.S. stations ......... 23 S and sometimes fatal condition is decom- pression sickness which is known as the "bends." Nitrogen narcosis occurs when gaseous nitrogen in the blood is under the high pressure like that experienced at depths greater than 30 meters; under these conditions dissolved nitrogen has a nar- cotic effect on the diver. Until recently biologists had only indi- rect evidence of how Weddell seals can dive to great depths and ascend rapidly without encountering either of these con- ditions. Anatomical studies and laboratory experiments in which Weddell seals under- went simulated dives suggested that at a certain depth the small air sacs (alveoli), which line the lungs and through which kilograms, and transported them to a site physical changes that occurred as seals gases are exchanged, collapse. This mech- on the 3-meter-thick sea ice of McMurdo dived. They programmed the computer to anism would protect the seal from the Sound. The selected site was 6 kilometers pump blood samples for 90 seconds at buildup of nitrogen in its system during from the nearest natural crack in the ice. selected depths during descent or ascent compression. Two 1-meter-diameter holes were drilled or after a specified length of time. Forty- in the ice. Over one of the holes a small seven samples were collected during dives In the 9 August 1985 issue of Science observation hut with a hole in its floor by the four seals to depths as great as 230 Warren Zapol of Massachusetts General was erected; the other hole provided the meters. Hospital in Boston and researchers from seals with an entrance to and exit from the United States, West Germany, Aus- the water. This arrangement ensured that tralia, and New Zealand reported the results the seals would return to the experiment Results of a 1983 investigation that provide the site to breathe after each dive since they The values of blood nitrogen tension first direct observations in support of this had nowhere else to breathe. from 29 samples showed that by the time theory. By using a specially designed com- the seals had reached 50 to 70 meters the puter-controlled system, they were able to After each seal had been anesthetized, amount of nitrogen in their blood had make in situ measurements, follow blood the researchers placed a catheter in a fore- peaked. As the dive progressed, blood nitro- nitrogen tension, and record other physi- flipper artery and advanced it to the aorta gen tension decreased. After analyzing cal changes as Weddell seals dived beneath for blood sampling. To monitor the seals sequential blood samples, the biologists McMurdo Sound sea ice. heart rate, they attached electrocardiogram combined these data with data on heart (ECG) leads to seals flipper and then con- rate, dive velocity, and depth. This analy- Description of the experiment nected the leads to an 8-bit microcomputer sis confirmed that the maximum concen- Dr. Zapol and his colleagues chose four backpack system. The microcomputer, tration of nitrogen occurred at approxi- male seals, weighing between 350 and 450 which was glued along with blood sam- mately 30 meters. pling equipment to the seals dorsal fur, also controlled a pressure-resistant sub- These results provide direct evidence that mersible peristalic pump to draw blood a Weddell seal protects itself from decom- through the catheter. In the observation pression sickness and nitrogen narcosis hut, a larger computer recorded heart rate, by limiting the lungs uptake of nitrogen diving depth, swimming velocity, and aortic and redistributing nitrogen to other parts blood temperature transmitted from the of the body. Nitrogen uptake stops when instrument pack while the seal rested on the gas-exchanging aveoli collapse at ap- the surface. proximately 28 meters; the blood nitro- gen tension is further reduced by redis- With the backpack computer Zapols tributing the nitrogen to other organs and research team could observe directly the tissues. Blood samples taken between 200 Editor Winifred Reuning Antarctic Journal of the United States, established in 1966, reports This photograph shows a Weddell seal with the 8-bit microcomputer used by Dr Zapols on U.S. activities in Antarctica and research team to monitor changes in the seals body during deep dives. related activities elsewhere, and on NSF photo courtesy of Warren ZapøI. trends in the U.S. Antarctic Research Program. It is published quarterly (March, June, September, and De- cember) with a fifth annual review issue by the Division of Polar Pro- grams, National Science Foun- dation, Washington, D.C. 20550. 4r Telephone: 202/357-7817. 5$ The Antarctic Journal is sold by the copy or on subscription through the U.S. Government Printing Office. Re- quests for prices of individual issues and subscriptions, address changes, and information about other subscrip- tion matters should be sent to the Superintendent of Documents, U.S. Government Printing Office, Washing- ton, D.C. 20402. The Director of the National Science Foundation has determined that the publication of this periodical is nec- essary in the transaction of the public business required by law of this agency. Use of funds for print- ing this periodical has been approved by the director of the Office of Man- agement and Budget through 31 March 1986. Antarctic Journal Sea-ice microorganism aids biotechnological research Aw Since 1980 Cornelius Sullivan and a team that catalytically are efficient to 0°C or ,/fr / of biologists from the University of South- that are able to be inactivated at moderate ern California (USC) have studied micro- temperatures. Dr. Sullivan suggests that algae and bacteria that grow in antarctic these bacteria, which have not been exam- sea ice. In August 1985 Dr. Sullivan and ined previously for antibiotic production, two USC microbiologist, Hiroaki Shizuya "may also be important sources of new and Hiromi Kobori, announced that they antibiotics." had isolated a new type of enzyme that Because the USC biologists found that may be useful in gene synthesis and clon- these bacteria often carry an extrachromo- ing from one of the antarctic microorgan- somal element called plasmids, they sug- isms. Dr. Sullivan, who is director for gest that plasmids are ubiquitous in natu- marine biology research at USC, and his ral microbial populations in the pristine associates describe the new enzyme as "50 marine ecosystem of Antarctica. times more potent" in its action than com- monly used enzymes. Enzymes—proteins formed in plants, animals, and bacteria—act as catalysts in starting or speeding specific chemical reac- NSF photo courtesy of Warren Zapol. tions. In gene synthesis and cloning, an References A Weddell seal comes up for air at one of the enzyme, alkaline phosphatase (APase), is isolated breathing holes drilled for this experi- used to remove certain groups of phos- Kottmeier, S.T., A.M. Muscat, L.L. Craft, ment. The electrocardiogram lead with the phate from RNA (ribonucleic acid) and J.E. Kastendiek, and C.W. Sullivan. computer backpack in the background are 1984. Ecology of sea-ice microbial com- visible in this photograph. DNA (deoxyribonucleic acid). DNA car- ries genetic information used to construct munities in McMurdo Sound, Antarc- living cells; RNA controls protein produc- tica, in 1983. Antarctic Journal of the tion in cells. Currently, an APase isolated United States, 19(5), 129-131. from the bacterium Escherichia coli (E.coli) is used in laboratories conducting genetic md 230 meters indicate that the amount engineering experiments. The disadvan- )f nitrogen in the seals blood never reaches tage of E.coli APase is that it is extremely evels high enough to produce nitrogen heat-resistant. Because simple heat treat- arcosis. ment cannot be used to inactivate E.coli APase, laboratories must use more elabo- They also found that hemoglobin con- rate procedures. mt increased during the first 17 minutes f a dive. The higher hemoglobin concen- Through their research in McMurdo ration increases the solubility of nitrogen Sound and the Weddell Sea, USC biolo- the blood by 8 to 10 percent and con- gists found that a group of bacteria in the ibutes to the decreased blood nitrogen sea ice grows rapidly in the permanently nsion during the dive.
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