Interannual variations in the lipids of the Antarctic pteropods Clione limacina and Clio pyramidata.

Antarctic pteropods, Clione limacina (Order Gymnosomata) and Clio pyramidata (order Thecosomata), were collected near Elephant Island, South Shetland Islands, during 1997 and 1998. Total lipid was high in C. limacina (29--36 mg g(-1) wet mass) and included 46% of diacy1glyceryl ether (DAGE, as % of total lipid) for both 1997 and 1998. DAGE was not detected in C. pyramidata, which had mainly polar lipid and triacy1glycerol. 1-O-Alkyl glyceryl ethers (GE) derived from the DAGE consisted primarily of 15:0 and 16:0, with lower 17:0 and a17:0. The principal sterols of both pteropods included trans-dehydrocholesterol, brassicasterol, 24-methylenecholesterol, cholesterol and desmosterol. Levels of 24-methylenecholesterol and desmosterol were lower in both pteropods in 1997 compared to 1998. C. limacina had high levels of the odd-chain fatty acids 17:1(n--8)c and 15:0 in contrast to C. pyramidata. The previously proposed source of elevated odd-chain fatty acids in C. limacina is via propionate derived from phytoplankton DMPT; another possible source may be from thraustochytrids, which are common marine microheterotrophs. C. pyramidata had twice as much PUFA as C. limacina, largely due to higher 20:5(n--3). The PUFA 18:5(n--3) and very long chain fatty acids (C(24), C(26) and C(28) VLC-PUFA) were only detected in 1998 pteropods. In comparison, 1996 samples of C. limacina contained lower DAGE levels, which also may reflect differences in diet and oceanographic conditions. Interannual variations in specific lipid biomarkers are discussed with respect to possible different phytoplankton food sources available in the AMLR survey area.

Lipids of gelatinous Antarctic zooplankton: Cnidaria and Ctenophora.

Cnidaria (Calycopsis borchgrevinki, Diphyes antarctica, Stygiomedusa gigantea, Atolla wyvillei, Dimophyes arctica) and Ctenophora (Beroe cucumis, B. forskalii, Pleurobrachia pileus, Bolinopsis infundibulum) were collected near Elephant Island, South Shetland Islands, during January and February 1997 and 1998. Total lipid was low in all zooplankton (0.1-5 mg g wet mass) and included primarily polar lipids (59-96% of total lipid). Triacylglycerols were 0-26% of total lipids, and wax esters were 0-11% in all species. Cholesterol was the major sterol in all Cnidaria (50-63% of total sterols) whereas in most ctenophores it was lower at 26-45%. These cholesterol levels are consistent with a combined carnivorous and phytoplanktivorous diet in the ctenophores, with the carnivorous diet more dominant in the Cnidaria. Other sterols included primarily trans-dehydrocholesterol, desmosterol, 24-methylcholest-5,22E-dien-3beta-ol, 24-nordehydrocholesterol, and 24-methylenecholesterol. Total stanols were 0-6% in all zooplankton. Eicosapentaenoic acid and docosahexaenoic acid were the major polyunsaturated fatty acids (PUFA) in all samples (7-25% of total fatty acids) except for A. wyvillei in which docosapentaenoic acid was 10% of total fatty acids. The PUFA 18:5n-3 was not detected in 1997 samples, but constituted 0.2-0.8% in most 1998 samples. Monounsaturated fatty acids included primarily 18:1n-9c, 16:1n-7c, and 18:1n-7c. The principal saturated fatty acids in all samples were 16:0, 18:0, and 14:0. These data are the first for many of these zooplankton species and the first sterol data for most species. The use of the signature lipid approach has enabled examination of aspects of trophodynamics not obtainable by conventional techniques.

Lipids and buoyancy in Southern ocean pteropods.

The lipids of Clione limacina, a Southern Ocean pteropod (order Gymnosomata), contain 28% diacylglyceryl ether (DAGE) (as percentage of total lipid) whereas the pteropod Limacina helicina (order Thecosomata) lacks DAGE. The alkyl glyceryl ether diols (1-O-alkyl glycerols, GE) of Clione DAGE are dominated by 16:0 (60%) and 15:0 (21%), in contrast with deep-sea shark liver DAGE, which is dominated by 18:1 GE. The fatty acid profiles of Clione and Limacina are similar (28-32% polyunsaturated, 26-34% monounsaturated) as are the sterols, which include 24-methylenecholesterol, transdehydrocholesterol, cholesterol, and desmosterol. This finding probably reflects the fact that Limacina is the major food source for Clione. Spongiobranchaea australis, another Southern Ocean pteropod (order Gymnosomata), has 0.9-1.7% DAGE, but has less lipid (3.3-4.8 mg/g lipid, wet weight) than Clione (50.8 mg/g lipid, wet weight). We propose a buoyancy role for DAGE in Clione since Limacina has bubbles for flotation which Clione lack; DAGE provides 23% more uplift than triacylglycerol at a concentration of 1.025 g/mL seawater.

Bone lipids of Jamaican reef fishes.

1. Fourteen species from 12 different families of fish from the Jamaican coral reef environment were analyzed for bone lipid content and class. Acanthurus bahianus (Acanthuridae), the ocean surgeon, had 29.7% lipid (as per cent dry wt) in the neurocranium. 2. Eight species had 7.4-17.9% lipid in the neurocranium and include A. chirurgus, Priacanthus arenatus, Equetus acuminatus, Eupomacentrus planifrons, A. coeruleus, Malacanthus plumeri, Haemulon flavolineatum and Pempheris schomburgki. 3. Five species had low bone oil (0.1-2.5% neurocranium lipid), including the chondrocranium of Urolophus jamaicensis, an elasmobranch. 4. Most fish stored more lipid in the neurocranium than in the vertebral centra. 5. Triglyceride is the major lipid class in most of these fishes with oily bones (74.1-93.7% as per cent lipid); cholesterol and phospholipid were two other lipid classes in the bones. 6. The average skeletal lipid (for neurocranium plus vertebral centra, as per cent total body lipid) for 13 species is 22.5% with a low of 5.5% in Sparisoma aurofrenatum and a high of 81.1% in Acanthurus chirurgus. 7. These data provide a basis for choice of a suitable experimental animal to study function of bone lipid. Acanthurus bahianus appears most suitable, because it has the most bone oil, is most common over Jamaican reefs and is easily obtained by trapping.

Bone lipids of Jamaican reef fishes

1. Fourteen species from 12 different families of fish from the Jamaican coral reef environment were analyzed for bone lipid content and class. Acanthrus bahianus (Acanthuridae), the ocean surgeon, had 29.7 percent lipid (as per cent dry wt) in the neurocranium. 2. Eight species had 7.4-17.9 percent lipid in the neurocranium and include A. chirurgus, Priacanthus arenatus, Equetus acuminatus, Eupomacentrus planifrons, A. ceoruleus, Malacanthus plumeri, Haemulon flacolineatum and Pempheris schomburgki. 3. Five species had low bone oil (0.1-2.5 percent neurocranium lipid), including the chondrocranium of Urolophus jamaicensis, an elasmobranch. 4. Most fist stored more lipid in the neurocranium than in the vertebral centra. 5. Triglyceride is the major lipid class in most of these fishes with oily bones (74.1-93.7 percent as per cent lipid); cholesterol and phospholipid were two other lipid classes in the bones. 6. The average skeletal lipid (for neurocranium plus vertebral centra, as per cent total body lipid) for 13 species is 22.5 percent with a low of 5.5 percent in Sparisoma aurofrenatum and a high of 81.1 percent in Acanthurus chirurgus. 7. These data provide a basis for choice of a suitable experimental animal to study function of bone lipid. Acanthrus bahianus appears most suitable, because it has the most bone oil, is most common over Jamaican reefs and is easily obtained by trapping. (AU)

Swimbladder membrane protein of an abyssal fish, Coryphaenoides acrolepis.

Protein components of the membranous foamy tissue collected from the swimbladder of Coryphaenoides acrolepis, a continental slope/deep sea grenadier fish, were partially fractionated and characterized by procedures used successfully for erythrocyte membrane proteins. Methods involving pH and ionic strength adjustment in the presence of EDTA and beta-mercaptoethanol resulted in some protein fractionation but no distinct separation or isolation of membrane proteins. Gel filtration by Sephadex G-100 and Sepharose 2B in the presence of dodecyl sulfate partially fractionated protein species between 18,000 and 150,000 molecular weight (as confirmed by dodecyl sulfate polyacrylamide gel electrophoresis). Low molecular weight proteins were resolvable into a few diffuse and streaky bands by dodecyl sulfate and chloral hydrate polyacrylamide gel electrophoresis, the former giving superior reso-ution. A major fraction of large molecular weight protein (greater than or equal to 40 X 10(6)) was not resolved by any method. A possible explanation for these unusual findings is that decompression due to rapid ascent of the fish from deep ocean caused irreversible alteration of swimbladder membrane proteins.

Bone lipids of marine fishes.

Assessment of candidates for investigation of bone lipid metabolism yielded the following findings. (1) A tropical marine butterflyfish, Chaetodon ornatissimus, had oil-filled bones (66-80% lipid, percent dry weight) hence may be a suitable condidate. (2) The tropical marine fishes Exallias brevis, Pomacentrus jenkensi, and Chromus agilis, and a Canadian fish Sebastes ruberrimus, had intermediate quantities of oil in their bones (12-49% lipid). (3) In all the foregoing species the major bone lipid was triglyceride, usually more abundant in skull than spine. Sterol and phospholipid were also present. (4) The major fatty acids of the triglycerides (and phospholipids) were 16:0, 18:0, 18:1, and C20, C22 acids. Those acids were dominated by 20:4, 20:5, 22:5, and 22:6. (5) There was more total unsaturation in the bone lipids of S. ruberrimus (from 10 degrees C water; 67-72% unsaturation) compared to the tropical fish (from 25 degrees C water; 32-67% unsaturation) with the exception of E. brevis. (6) One of the tropical species (Arothron meleagris) and a Canadian Chimaeran (Hydrolagus colliei) contained only 1-3% lipid in their bones.