Dominant Lipid Class Research Articles

Chemical composition and lipids classes of the freshwater fish tilapia do Nilo,Oreochomis niloticus

The purpose of this work is to quantify lipid classes founded in fillets of Tilapia do Nilo, Oreochomis niloticus. The total lipids (TL) were fractionated by open column chromatography in neutral lipids (NL), glyceroglycolipids (GL) and glycerophospholipid (PL). Five lots of samples, each one containing four specimens, were obtained from retail stores in Fortaleza (Ceará State - Brazil) in sep, oct, nov and dec of 2011. The TL was averaged in 3.8% of muscle, on wet mass basis. The dominant lipid class was NL averaging at 74.5% in relation to the TL or 2.9g/100g of fillet. The GL and PL contributed on average with 1.5% (61mg/100g of fillet) and 23.1% (885mg/100g of fillet), respectively. The approximate composition had average of 76.0% moisture, 19.3% total protein, and 2.0% ash.

Chemical composition and molecular speciation of the triacylglycerol of the oils of Lonchocarpus sericeus and Lonchocarpus cyanescens

Proximate composition of the seeds and chemical analysis of the oils of Lonchocarpus sericeus and Lonchocarpus cyanescens were determined. The oil content of the seed of L. cyanescens is 29.71 ± 0.20% while that of L. sericeus is 28.00 ± 0.50%. The seeds as well as the oils of L. cyanescens and L. sericeus were found to be rich in K, Na and Fe. Linolenic (C18:3) and oleic (C18:1) acid are the dominant fatty acids while the neutral lipids the dominant lipid class in the oils. Phytol, sterols, beta-tocopherol and hydrocarbons were identified in the unsaponifiable matters of the oils using GC–MS. The HPLC results revealed the presence of glycolipids, which are monogalactosyldiacylglycerol, digalactosyldiacylglycerol, digalactosylmonoacylglycerol and monogalactosylmonoacylglycerol. Molecular speciation of the triacylglycerol revealed the presence of molecular species with equivalent carbon chain numbers C36 (L. sericeus) and C50 (L. cyanescens) to be dominantly present in the oils.

지방 바이오마커를 활용한 북서태평양에서 요각류(Euchaeta sp. and Pleuromamma spp.)의 서식 위도별 영양상태 및 먹이원 연구

In order to ascertain latitudinal variation of lipid contents and compositions in copepods, we collected warm water copepod species (Euchaeta sp. and Pleuromamma spp.) from four different regions from low (sub-tropical) to mid (temperate) latitudes in the Northwest Pacific Ocean. Total lipid contents of Pleuromamma spp. were about 11 <TEX>$ug{\cdot}ind^{-1}$</TEX> with little latitudinal variation, whereas Euchaeta sp. showed slightly higher lipid content (20 <TEX>$ug{\cdot}ind^{-1}$</TEX>) than Pleuromamma spp. with latitudinal gradient (low at subtropic and high at temperate). Wax esters, known as the major storage lipid classes, were found to be the dominant lipid classes (accounting for more than 35% of total lipids) in Euchaeta sp., whereas in Pleuromamma spp., phospholipids, known as cellular membrane components, were the dominant lipid classes. However, the exception was specimens from warm pool region exhibiting dominance in storage of lipids as a form of triacylglycerols. Among fatty acids, polyunsaturated fatty acids (PUFA), especially docosahexaenoic acid (DHA : 22:6(n-3)) (about 35% of total fatty acids), were most abundant in Euchaeta sp., while saturated fatty acids (SAFA), specially hexadecanoic acid (16:0) (about 30% of total fatty acids), were most abundant in Pleuromamma spp.. Among the neutral fraction of lipids, phytol, originated from the side chain of chlorophyll, was found in all samples which generally indicate active copepods feeding on algae. While only trace amounts of short-chain fatty alcohols were found in Pleuromamma spp., significant amounts of fatty alcohols were found in Euchaeta sp.. Particularly, significant amounts of long chain monounsaturated fatty alcohols (20:1 and 22:1), generally found in cold water species, were found in Euchaeta sp. from low latitudes. The latitudinal variation of trophic lipid markers in these copepods could be significantly related with in-situ food availability and species-specific diet preference. The result of this study suggests that the lipid contents and compositions in copepods may not only indicate their nutritional condition and feeding ecology but also provide insight into species-specific living strategies under different environmental conditions (i.e. water temperature, food availability).

Effects of nitrate and oxygen on photoautotrophic lipid production from Chlorococcum littorale

Effects of oxygen and nitrate on fatty acid/lipid production from a highly CO(2)-tolerant microalgal species Chlorococcum littorale were examined under photoautotrophic conditions of 295 K, a light intensity of 170 μmol-photon m(-2) s(-1), a bubbling CO(2) concentration of 5% (v/v) and bubbling oxygen concentrations to be volumetrically adjusted by mixing oxygen gas with inert nitrogen gas at concentrations ranging from 0% to 95% (v/v). The results showed that maximum fatty acid content reached ca. 34 wt.% under oxygen-freely bubbling conditions and this value decreased to be ca. 20 wt.% when air-like oxygen concentration of 20% was chosen. This means that degree of the accumulation strongly depended on the level of bubbling oxygen concentrations, which can be a crucial factor after nitrogen depletion in the photoautotrophic culture system. TLC-FID/FPD analyses showed that triglycerides were found to be a dominant lipid class for this accumulation.

Comparative lipid dynamics of euphausiids from the Antarctic and Northeast Pacific Oceans

To better understand the feeding and reproductive ecology of euphausiids (krill) in different ocean environments, lipid classes and individual lipid components of four different species of euphausiids from Northeast Pacific (temperate species) and Southern Ocean (Antarctic species) were analyzed in animals from multiple life stages and seasons. The dominant krill species in the Northeast Pacific Euphausia pacifica and Thysanoessa spinifera, were compared to the two major Antarctic species, Euphausia superba and E. crystallorophias. Analysis comprised total lipid and lipid classes together with individual fatty acid and sterol composition in adults, juveniles, and larvae. Antarctic krill had much higher lipid content than their temperate relatives (10–50 and 5–20% of dry mass for Antarctic and temperate species, respectively) with significant seasonal variations observed. Phospholipids were the dominant lipid class in both temperate krill species, while neutral storage lipids (wax esters and triacylglycerols for E. crystallorophias and E. superba, respectively) were the major lipid class in Antarctic krill and accounted for up to 40% of the total lipid content. Important fatty acids, specifically 16:0, 18:1ω9, 20:5ω3, and 22:6ω3, were detected in all four krill species, with minor differences between species and seasons. Detailed lipid profiles suggest that krill alter their lipid composition with life stage and season. In particular, larval Antarctic krill appear to utilize alternate food resources (i.e., sea-ice associated organisms) during austral winter in contrast to juveniles and adults (i.e., seston and copepods). Lipid dynamics in krill among krill in both systems appear closely linked to their life cycle and environmental conditions including food availability, and can provide a more complete comparative ecology of euphausiids in these environmentally distinct systems.

북서태평양에서 난수성(Pleuromamma sp.)과 냉수성(Neocalanus plumchrus) 요각류의 지방 함량 및 구성 분석을 통한 생리/생태 비교

In an effort to better understand the physiological and ecological differences between warm and cold water copepod species in Korean waters using lipid contents and compositions, two species of copepods (Pleuromamma sp. as a warm water species and Neocalanus plumchrus as a cold water species) were collected from the Northwest Pacific and East Sea/Sea of Japan, respectively. The cold water species showed two fold higher lipid contents than the warm water species (11% vs. 5% of dry weight). Wax esters, known as one of the major storage lipid classes, were found to be the dominant lipid class (accounting for 64% of total lipids) in the cold water species, whereas, in the warm water species, phospholipids, which are known as membrane components, were the dominant lipid class (accounting for 43% of total lipids),with a trace amount of the storage lipids as a form of triacylglycerols (<TEX>${\leq}1%$</TEX> of total lipids). With regard to the fatty acid compositions, saturated fatty acids (SAFA), especially 16:0 (about 30% of total fatty acids), were most abundant in the warm water species, whereas the polyunsaturated fatty acids (PUFA), particularly eicosapentaenoic acid (EPA : 20:5(n-3)) (<TEX>${\geq}16%$</TEX> of total fatty acids), were most abundant in the cold water species. Among the neutral fraction of lipids, phytol, originating from the side chain of chlorophyll and indicative of active feeding on phytoplankton, was detected only in the warm water species. Significant quantities of fatty alcohols were detected in cold water species, particularly long-chain monounsaturated fatty alcohols (i.e. 20:1(n-9) and 22:1(n-11)), which are well known to abound in cold water herbivorous copepods. However, only trace amounts of short-chain fatty alcohols were detected in the warm water species. Twelve different kinds of sterols were detected in these copepod species, with cholest-5-en-<TEX>$3{\beta}$</TEX>-ol (cholesterol) and cholesta-5, 24-dien-<TEX>$3{\beta}$</TEX>-ol (desmosterol) dominating in cold and warm water species, respectively. In addition, for the warm water species (Pleuromamma sp.), we assessed the latitudinal gradients of lipid contents and compositions using samples from three different latitudinal regions (Philippine EEZ, Japan EEZ, and the East China Sea). Although no latitudinal gradients of lipid contents were detected, the lipid compositions, particularly dietary fatty acid markers, varied significantly with the latitude. The findings of this study confirm that the distribution of lipid contents and compositions in copepods may not only indicate their nutritional condition and diet history, but may also provide insights into their living strategies under different environmental conditions (i.e., water temperature, food availability).

The role of lipids during embryonic development of the euphausiids Euphausia pacifica and Thysanoessa spinifera

To understand the role of lipids during early embryogenesis, major lipid classes together with individual fattyacid and sterol composition were determined in embryos from multiple developmental stages of the euphausiids Euphausia pacifica and Thysanoessa spinifera. Average lipid content in embryos of E. pacifica and T. spinifera from the earliest stage (multicell) were 4.45 and 3.69 mg embryo21, respectively. During development, the lipid content decreased at similar rates in the embryos of both species. In contrast to many crustacean eggs, phospholipids were the dominant lipid class in all embryonic stages, with decreasing concentrations seen during development. Individual fatty acids and sterols showed selective utilization during early developmental stages. The dominant fatty acids were 16:0 and 16:1v7 and 20:5v3, with most polyunsaturated fatty acids preferentially metabolized throughout early stages. An exception was 22:6v3, which remained near constant through all stages. Cholesterol was the dominant sterol (.82% of total sterols) in embryos, with only minor changes during development. The appearance of algal sterols and fatty alcohols, including phytol, in T. spinifera embryos suggests that considerable amounts of algal lipids are directly allocated to eggs during vitellogenesis. Despite the substantial changes in lipid amount and composition during embryo development, the presence of phospholipids as the dominate lipid store acts to moderate changes in egg-sinking rate for both species until the late (early and late limb-bud) stages of development.

Understanding the trophic role of the Antarctic ctenophore, Callianira antarctica, using lipid biomarkers

To better understand the trophic role of ctenophores in Antarctica during austral fall and winter, a major species of cydippid ctenophore, Callianira ant- arctica, was collected during April/May (fall) and August/September (winter) 2002 in the vicinity of Marguerite Bay. Lipid content, lipid classes, fatty acids, fatty alcohols and sterols were analyzed in animals, to- gether with lipid biomarkers in krill and copepod species representing potential ctenophore prey. Lipid content in ctenophores collected in winter was slightly higher than from animals in fall (4.8 and 3.5% of dry weight, respectively). Polar lipids were the dominant lipid class in ctenophores, accounting for over half of the lipid content, with significant amounts of free fatty alcohols (more than 10% of total lipid content) detected. Lipid- class composition, however, differed significantly be- tween seasons, with significant amounts of neutral lipid (wax esters and triacylglycerols) only detected in animals from fall. Although the dominant lipid classes in cte- nophores varied between fall and winter, individual lipids (i.e., fatty acids, alcohols and sterols) showed only minor changes between seasons. Specifically, long-chain polyunsaturated fatty acids (20:5(n-3) and 22:6(n-3)) found in high abundance in larval krill were also ele- vated in ctenophores collected in winter. Very high amounts of monounsaturated fatty alcohols, particu- larly 20:1(n-9) and 22:1(n-11), known to be important components of wax esters in calanoid copepods, were also observed. Multivariate analysis using the suite of lipids found indicated that copepods are an important diet item for ctenophores in the study area. Results further suggest that C. antarctica feed actively year- round, with larval krill providing a food resource during austral winter.

Identifying potential prey of the pelagic larvae of the spiny lobster Jasus edwardsii using signature lipids

Signature lipid analyses were used to identify the natural prey of the pelagic phyllosoma larvae of the spiny lobster Jasus edwardsii. Lipid class, fatty acid and sterol composition were determined for associated potential prey items and for phyllosomes captured between 50 and 90 km offshore from the northeastern coast of New Zealand. Phospholipid was the dominant lipid class in all potential prey items and the transparent phyllosomes. The levels of other lipid classes varied between potential prey items, with the next most abundant classes being triacylglycerols, free fatty acids and sterols. A limited number of the potential prey items also contained wax ester. Major fatty acids in all potential prey items were generally 22:6ω3 (docosahexaenoic acid), 16:0, 18:1ω9c, and 20:5ω3 (eicosapentaenoic acid). Multivariate analyses of fatty acid and sterol content of the samples grouped the phyllosoma samples together regardless of their developmental stage or their collection location. However, the phyllosomes were not associated with any of the general groupings of pelagic ascidians, amphipods, chaetognaths, pteropods, euphausiids, fish, copepods or particulate matter that were formed by the statistical analyses. Although the sterol profiles of the potential prey items showed considerable variation, the phyllosomes contained predominately cholesterol, suggesting that other dietary sterols are converted to cholesterol or metabolised by the phyllosomes. Therefore, the use of sterols for tracing the prey of J. edwardsii phyllosoma appears to be limited. Our results suggest that phyllosomes are opportunistic predators that feed on a variety of prey and are preferentially retaining specific diet-derived fatty acids.

Lipid and fatty acid composition of Antarctic shrimp eggs (Decapoda: Caridea)

Eggs of the decapod shrimps, Chorismus antarcticus, Nematocarcinuslanceopes and Notocrangon antarcticus were taken to analyse their morphometric, lipid and fatty acid composition. Almost all females carried undifferentiated eggs (stage I). The average number of recently extruded eggs was lowest in C. antarcticus with 163 eggs, and highest in Nematocarcinus lanceopes with 1,220 eggs, while Notocrangon antarcticus produced on average 350 eggs. The lipid content (% of dry mass) of the eggs was 18.8% for C. antarcticus, 14.3% for Notocrangon antarcticus and 18.1% for Nematocarcinus lanceopes. Dominant lipid classes in eggs of all species were phospholipids and triacylglycerols. The storage lipid, triacylglycerol, was slightly elevated in the eggs of Nematocarcinus lanceopes (mean of 52.7%) compared to the other two species. The fatty acid compositions of the decapod eggs were similar in the three species. Dominant fatty acids were 20:5(n-3), 18:1(n-9), 16:1(n-7), 16:0 and 18:1(n-7), comprising 75.8–78.4% of total fatty acids. Among the species, the eggs of C. antarcticus had the highest proportions of polyunsaturated fatty acids (39.6%), dominated by 20:5(n-3), and the lowest percentage of monounsaturates (41.8%). The eggs of Nematocarcinuslanceopes and Notocrangonantarcticus contained almost the same proportion of polyunsaturated fatty acids (28.0% and 28.4%, respectively), whereas Nematocarcinus lanceopes had the highest amount of monounsaturates due to the dominance of 18:1(n-9). Based on our findings, we assume that eggs produced by polar decapod crustaceans do not contain substantially more lipids than related species from temperate or tropical regions. However, additional studies are necessary to substantiate any general conclusion about the relationship of egg lipid content and composition with climatic zones.

Northern Shrimp (Pandalus borealis) Recruitment in West Greenland Waters Part II. Lipid Classes and Fatty Acids in Pandalus Shrimp Larvae: Implications for Survival Expectations and Trophic Relationships

Lipid class and fatty acid compositions were determined in shrimp larvae (Pandalus borealis and P. montagui) collected along transects across banks on the West Greenland shelf in June 1999, May and July 2000. The lipid class contents were investigated as indices of larval shrimp lipid condition and food type. Fatty acid compositions were investigated for lipid biomarkers to establish trophic relationships between larval shrimp and potential prey. Phospholipids were the dominant lipid class in all six pelagic development stages of larval P. borealis and P. montagui, accounting for 80 to 92% of the total lipid. In all six stages the contents of free fatty acids were more abundant than triacylglycerol. With increasing larval size from hatching to a carapace length of ~2.3 mm, there was a decreasing trend in the contents of hydrocarbons attributed to reduced amount of phytoplankton in the diet. Triacylglycerol (TG) content to wet weight ratio was investigated as index of nutritional larval condition and survival potential. Proportions of larvae with TG indices >0.2 were relatively high in May 2000 and June 1999, but generally low in July 2000. The fatty acids 16:0, 16:1n-7, 18:0, 18:1n-9, 18:1n-7, 20:5n-3, and 22:6n-3 were major lipid components of the larvae and their mean proportions varied within relatively small ranges between larval stages. The dominant fatty acids were 16:0, 20:5n-3, and 22:6n-3 with average proportions of about 17%, 20%, and 13%, as percentage of total fatty acids. Biomarkers for algae (16:0, 16:1n7, 18:1n-7, 20:5n-3, diatoms: elevated 16:1n-7/16:0 ratios), flagellates (18:0, 18:4n-3, 22:6n-3), and zooplankton (18:1n-9, 20:1n-9, 22:1n-11) indicate that larval P. borealis and P. montagui are omnivorous. ZI larvae in high concentrations at coastal and fjord stations in May 2000 and most larvae (ZIV–ZVI) from July 2000 were low in lipid. Larvae from June 1999 had relatively high lipid contents probably due to better feeding and growth history. Our results suggest variability in growth and survival expectations of larvae related to variations in larval food availability between years.

Lipid class dynamics during development in early life stages of shortbelly rockfish and their application to condition assessment

Lipid class dynamics and the relationship between weight and length were analysed during early life stage (ELS) development in wild populations of shortbelly rockfish Sebastes jordani to investigate their utility in a condition or nutritional status assessment. Analyses from more than 3000 field‐captured shortbelly rockfish indicated little variation in weight for a given length and provided limited application in the assessment of condition. The fractionation of total lipids into individual classes revealed trends in lipid metabolism throughout development. These trends were described best using a stage‐specific regression model, since Sebastes show defined early life history transitions. Among developmental stages, triacylglycerols (TAG) and polar lipids (PL) were the dominant lipid classes and cholesterol (CHOL), sterol/wax esters, and nonesterified fatty acids were found in lower concentrations. In the preflexion stage, low concentrations and constant levels of TAG along with the combined influence of endogenous and exogenous sources of energy compromised the use of TAG as an index of nutritional status. However, during flexion through juvenile stages, TAG levels increased indicating an accumulation of energy reserves with development, thus providing a valid indicator of nutritional status in later stages. Large fluctuations in PL concentrations during development suggested complex metabolism which may be due to changes in cell volume and cell membrane proliferation with development as well as catabolism. CHOL declined in larval stages, then remained constant with increasing size through the juvenile stage, negating its use as a normalizer for variations of mass in a TAG/CHOL ratio prior to juvenile transformation. This study provides the first documentation of lipid dynamics during early life stages following parturition in a marine viviparous teleost.

Spatial variation in density, mean size and physiological condition of the holarctic amphipod Diporeia spp. in Lake Michigan

Summary We examined spatial patterns in population characteristics (density, biomass, mean body length) and physiological condition (lipid content, length‐weight) of the amphipod Diporeia spp. in Lake Michigan by collecting samples at up to 85 sites in late summer 1994 and 1995. Variables were examined relative to water depth and three lake regions: south, central and north. Most major river systems are found in the south, and this region is more nutrient‐enriched compared to the north. Over all sites, mean density was 5240‐2, biomass was 4.1g dry wt m‐2, and mean body length was 5 mm. While maximum densities were related to depth, with a peak at 30–70 m, greatest densities occurred on the west side of the lake, and low densities were found in the south‐east, north‐east and lower Green Bay. High densities in the west probably resulted from upwelling, and reduced densities in the south‐east may reflect food competition with Dreissena polymorpha (zebra mussel). Lipid content, weight per unit length, and mean length declined with increased water depth, but depth‐related trends were most evident in the south. Overall, mean lipid content and weight per unit length were significantly lower in the south (16.6% dry wt, 0.59 mg at 5 mm body length) compared to the north (23.7% dry wt, 0.78 mg at 5 mm body length). These regional differences may have resulted from greater diatom availability in the north and competition from D. polymorpha in the south. Triacylglycerols and phospholipids were the dominant lipid classes in all three regions. Although the mean proportion of triacylglycerols, the energy‐storage lipid, was lower in the south than in the north, regional differences in proportions of lipid classes were not significant. Mean lipid content and weight per unit length of Diporeia in the south were lower than values found in the late 1980s prior to the establishment of Dreissena. Mean lipid content of mature individuals is now at levels considered a minimum for successful reproduction.

Composição química e classes de lipídios em peixe de água doce Curimatã comum, Prochilodus cearensis

O presente trabalho teve como objetivo obter dados quantitativos sobre as classes de lipídios presentes no filé de curimatã, Prochilodus cearensis. Os lipídios totais (LT) foram fracionados em classes de lipídios neutros (LN), gliceroglicolipídios (GL) e glicerofosfolipídios (PL) através de cromatografia em coluna aberta de sílica gel 60 (70-230 mesh). As análises foram realizadas em quatro lotes de amostras contendo cada uma três exemplares, adquiridos em feiras livres de Fortaleza-CE, nos meses de março, maio, junho e julho de 1998. Os LT representaram em média 3,8% em relação ao peso fresco da amostra. A classe lipídica dominante foi de LN com média de 75,1% dos LT ou 2,9g/100g de filé. Os GL e PL contribuíram em média com 1,6% (61mg/100g de filé) e 23,3% (885mg/100g de filé), respectivamente. A composição química centesimal apresentou média de 76,3% de umidade, 18,6% de proteína total e 1,3% de cinza.

Functional biodiversity of lipids in Antarctic zooplankton: Calanoides acutus, Calanus propinquus, Thysanoessa macrura and Euphausia crystallorophias

Zooplankton samples were collected in January 1993 off Dronning Maud Land along a transect from open waters to the marginal ice zone close to the Antarctic ice shelf. Thysanoessa macrura was caught in open waters while Calanoides acutus and Calanus propinquus were mainly sampled between ice floes in the marginal ice zone. The “ice-krill”Euphausia crystallorophias was found over the shelf directly associated with ice floes. T. macrura had a lipid content up to 36% of its dry weight with the dominant lipid class, wax ester, accounting for 45–50% of the total lipid. The predominance of 18:1 fatty alcohols is the striking characteristic of the wax esters. Small specimens of E. crystallorophias had lipid levels up to 26% of their dry weight with, unexpectedly, triacylglycerols being the dominant lipid (up to 41% of total lipid). The small levels of wax esters in these animals (3–6% of total lipid) had phytol as a major constituent. Large specimens of E. crystallorophias had up to 34% of their dry weight as lipid, with wax esters (47% of total lipid) dominated by 16:0 and 14:0 fatty alcohols as the major lipid. Calanus propinquus had lipid levels of up to 34% of their dry weight, with triacylglycerols (up to 63% of total lipid) being the dominant lipid. High levels of 22:1 (n-9) fatty acid were present in the triacylglycerols. Calanoides acutus had lipid levels up to 35% of the dry weight with wax esters accounting for up to 83% of total lipid. High levels of (n-3) polyunsaturated fatty acids were recorded with 20:5(n-3), 22:6(n-3) and 18:4(n-3) being the dominant moieties. On the basis of their lipid compositions we deduce that: (1) Calanoides acutus is the strictest herbivore among the four species studied, heavily utilizing the typical spring bloom; (2) T. macrura is essentially omnivorous, probably utilizing the less defined bloom situations found in oceanic waters; (3) E. crystallorophias is an omnivore well adapted to utilize both a bloom situation and to feed on ice algae and micro-zooplankton associated with the ice; (4) Calanus propinquus seems to be the most opportunistic feeder of the four species studied, probably grazing heavily on phytoplankton during a bloom and, during the rest of the year, feeding on whatever material is available, including particulates, flagellates and other ice-associated algae. We conclude that the different biochemical pathways generating large oil reserves of different compositions, enabling species to utilize different ecological niches, are major determinants of biodiversity in polar zooplankton.

Lipid dynamics in anadromous Arctic charr, Salvelinus alpinus (L.): seasonal variations in lipid storage depots and lipid class composition

Changes in lipid class composition of tissues of anadromous Arctic charr, Salvelinus alpinus, were studied in relation to seasonal patterns of lipid deposition and lipid mobilisation. Charr of a north Norwegian population were collected in late May when fish were migrating towards the sea, and in mid-July when the fish re-entered fresh water. Some maturing fish captured in mid-July were held in captivity until late September to assess lipid dynamics associated with maturation. The carcass (head, fins, skeleton and skin) accounted for approx. 50% of the total body lipid content when the fish re-entered fresh water from the sea. Triacylglycerols (TAG) comprised 75-80% of the carcass lipid in ascending charr, confirming that the carcass is a major lipid depot. The skeletal muscle also represented a major lipid store: muscle of ascending charr contained 35-40% of the body lipids, with TAG being dominant (approx. 75% of muscle lipid). The gut (gastrointestinal tract and visceral lipid) and liver of ascending charr each held only 4-5%; of the body lipid, TAG being the dominant lipid class in both of these depots (Gut TAG: 60-65%; Liver TAG: 50-55%). Body lipid decreased 30-40% during maturation: lipids were depleted from all depots, but mobilisation of from the carcass and muscle was quantitatively the most important. In mature females, the ovaries held almost 25% of the body lipid, with the proportion of TAG exceeding that of polar lipids (PL)(TAG: 62%; PL 12.4%). In the mature males, the testes accounted for less than 3% of the total lipids. TAG tended to dominate the testis lipids (TAG: 29.5%), but there were also quite high proportions of free fatty acids, cholesterol and polar lipids (FFA: 23.5%; C: 15%; PL 9.7%). Females lost approx. 80% of their body lipid during spawning and overwintering, the majority of this being TAG. Males also lost large amounts of TAG during the winter, but in contrast to the females lipid depletion amounted to only 50-55% of that present at the time of ascent into fresh water.

Rapid procedure for the isolation and analysis of fatty acid and fatty alcohol fractions from wax esters of marine zooplankton

A rapid and simple method for the isolation of fatty acid methyl esters and fatty alcohols from the lipid fraction of marine zooplankton is described. Wax esters are the dominant lipid class in most calanoid copepods and trans-esterification results in a high fatty alcohol content in the analytical extract. Current procedures for the separation and purification of lipid classes by preparative thin-layer chromatography are time-consuming and are subject to low recovery of the analytes. In this method, fatty acid methyl esters and fatty alcohols were separated by liquid chromatography using silica or honded amino-silica as the stationary phase. The procedure is equally applicable to the analysis of zooplankton with low wax ester (and hence fatty alcohol) content, for example, a number of species of euphausiid and, generally, for samples of low mass.

The Lipid Composition of the CoccolithophoreEmiliania Huxleyiand Its Possible Ecophysiological Significance

The lipid class and fatty acid composition of eight geographically disperse isolates ofEmiliania huxleyi, grown under 12 h L:D cycles and harvested during logarithmic and stationary growth phases, were examined. Cell size and chlorophyll content tended to decrease from logarithmic to stationary growth phase, Methyl and ethyl ketones were the dominant lipid classes, although proportions exhibited no clear pattern either between strains or growth phases. Neutral lipid hardly accumulated over the course of the growth experiments, and triacylglycerol was either absent or only present at low levels. In all strains with the exception of a South African isolate, levels of total fatty acid per cell decreased markedly between logarithmic and stationary phases, primarily attributable to reductions in the levels of saturated and monounsaturated fatty acids. Major fatty acids in all strains during both growth phases were 14:0,16:0,18:1 (n-9), 18:4 (n-3), 18:5 (n-3) and 22:6 (n-3). Although all strains were rich in polyunsaturated fatty acids (47–72% of total fatty acids) stationary phase cultures consistently contained the highest proportions. The polyunsaturated fatty acid docosahexanoic acid (22:6, n-3) was the most abundant fatty acid in all strains, comprising a maximum of 38·4% of total fatty acids in strain M 181 during stationary phase. Multivariate analysis (PCA) allowed logarithmic and stationary phase cultures to be distinguished although no obvious intra-isolate variability was apparent. The results are discussed in terms of the importance of lipids for the ecophysiology of E.huxleyiand the role of this dominant coccolithophore in the marine food chain.

Mesoscale distribution and population dynamics of Rhincalanus gigas and Calanus simillimus in the Antarctic Polar Open Ocean and Polar Frontal Zone during summer

Two dominant Antarctic copepod species, Rhincalanus gigas and Calanus simillimus, were sampled at stations along a 420 km transect running from Maurice Ewing Bank (50°S, 42°W) towards South Georgia (54°S, 37.5°W) during early January 1994 and again 1 mo later. The transect spanned the Polar Frontal Zone (PFZ), crossing the Polar Front (PF) into Antarctic surface waters. In January, diatom blooms were present immediately south of the PF and at open ocean stations further south where unusually high total pigment levels up to 800 mg m-2 were recorded. In early January, north of the PF, R. gigas had not yet commenced spawning although recruitment had begun to the south. Early stages of C. simillimus copepodites were, however, present at all stations sampled. South of the PF both gonad maturity and lipid levels in R. gigas showed a clear positive relationship with the elevated pigment concentrations. C. simillimus females, on the other hand, were ripe at the majority of stations sampled regardless of pigment levels. A month later postbloom conditions were present over the greater part of the transect and the summer generation of both species was present at all stations. A proportion of the summer generation of C. simillimus had already reached adulthood and their gonads were maturing. The populations of both species were older in PFZ waters, and mean population age showed a strong correlation with water temperature. Prosome length of stages CIV, CV and CVI-female R. gigas was negatively correlated with sea surface temperature. This was not the case for C. simillimus females, suggesting that they had been recruited earlier in the season under different environmental conditions. Lipid analysis indicated that R. gigas predominantly stored wax esters, in contrast to C. simillimus where the dominant lipid class was triacylgycerol. These observations coupled with literature data on feeding and seasonal vertical distribution seem to indicate fundamently different life history patterns.

Seasonal and inter-annual changes in planktonic biomass and community structure in eastern Antarctica using signature lipids

The total lipid, fatty acid, sterol and pigment composition of water column particulates collected near the Australian Antarctic Base, Davis Station, were analysed over five summer seasons (1988–93) using capillary GC, GC-MS, TLC-FID and HPLC. Maximum lipid concentrations usually occurred in samples collected in December and January and corresponded with increased algal biomass. Polar lipids were the dominant lipid class. Both lipid profiles and microscopic observations showed significant variation in biomass and community structure in the water column both intra- and interannually. During the period of diatom blooms (predominantly Nitzschia spp.) the dominant sterol and fatty acid were trans-22-dehydrocholesterol and 20:5 ω3, respectively, which were accompanied by a high 16:1 ω7c to 16:0 ratio. Very high polyunsaturated fatty acid and total lipid concentrations were measured during diatom blooms in the area. Bacterial markers increased in concentration after the summer algal blooms in each year. C 30 sterols also increased in concentration during the latter half of all summers. Samples collected from the fjords contained greater biomass and diversity in algal and bacterial markers than samples from coastal sites. Signature lipids for the prymnesiophyte Phaeocystis sp., thought to be seasonally abundant in Antarctic waters, were identified in field samples over the five summer seasons studied. Blooms of this alga exhibited high 14:0, brassicasterol, low levels of polyunsaturated fatty acids and a low 16:1ω7c to 16:0 ratio. Based on the lipid profiles, the overall abundance of Phaeocystis sp. throughout the five summer seasons was sporadic and in most summers the abundance was low; these findings suggest Phaeocystis sp. is not always a major alga in this coastal region of Antarctica.