Assessment of storage lipid accumulation patterns in eucalanoid copepods from the eastern tropical Pacific Ocean (original) (raw)
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Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology, 2016
Lipids of Neocalanus cristatus and Eucalanus bungii (C3 to adults), collected in March, May, and December from various depths (0-2000m) were studied in the Oyashio region, western North Pacific. Total lipid and wax ester contents of younger N. cristatus stages increased during the development, being higher in May than in March and December. Major fatty acids of younger N. cristatus were 16:0, 20:5(n-3), and 22:6(n-3) and the dominant alcohols were 16:0, 16:1(n-7), 20:1(n-9)/(n-11) and 22:1(n-11). The energy-rich 20:1 and 22:1 moieties increased from the younger to the adult stages showing the importance of lipid biosynthesis which may be advantageous for successful overwintering and reproduction at depth. The 16:4(n-1) fatty acid, characteristic of a diatom diet increased in May, particularly in the younger stages. Our results suggest that the diatom-dominated feeding mode of younger N. cristatus during the spring bloom is important for an effective accumulation of wax esters. In co...
Marine Chemistry, 2012
Two of the dominant Southern Ocean copepods, Calanus simillimus and Calanus propinquus, are known for their lipid storage via triacylglycerols indicating year-round activity, as opposed to diapausing species, which accumulate wax esters. We studied the lipid and fatty acid compositions of C. simillimus (CV stages) with focus on its ability to produce unusually long-chain monounsaturated fatty acids. Besides the biosynthesis of high-energy fatty acids with 20 and 22 carbon atoms, the occurrence of fatty acids with 24 carbon atoms accounting for up to 15% of total fatty acids is intriguing. Their double bond positions were unequivocally determined as (n−9), (n−11) and (n−13) by DMOX derivatisation. The dominant isomer was 24:1(n−11) contributing up to 8% to the total fatty acids. The major fatty acids were the isomers 22:1(n−11) and (n−9) averaging 20% and 10%, respectively. A re-evaluation of fatty acid data of C. propinquus also revealed 24:1 fatty acids exhibiting on average 5% with (n − 11) and (n − 9) as main isomers. The principal fatty acids were also 22:1(n − 11) and (n − 9), but in contrast to C. simillimus both fatty acids occurred in equally high amounts of about 20%. The de novo biosynthesis of these long-chain monounsaturated fatty acids generally represents a very efficient energy storage mode. Chain elongation to 22 and even to 24 carbon atoms in C. propinquus and further optimised by C. simillimus yields high-energy compounds for these triacylglycerol-storing copepods. Biosynthetic pathways for the fatty acids are proposed and discussed in view of the well-adapted life cycle strategies of the two species, which have to cope with a pronounced seasonal food supply in the Southern Ocean.
Antarctic Science, 2011
Changes in adult weight, lipid and fatty acid composition per lipid class were studied over a complete seasonal cycle in Drepanopus pectinatus Brady. This copepod displayed a strong seasonality in adult individual weight and total lipid content. Stages C3 to adult from a summer cohort were compared in terms of lipid and fatty acid structure. Changes in lipid content were related to wax esters and polar lipids (PL) while triacylglycerols (TAG) and cholesterol remained minor constituents except at the end of winter. Changes in fatty acid composition of different lipid classes showed that food limitation in winter was high enough to affect 22:6n-3 (DHA) content in PL, and provoke accumulation of maximal percentages of bacterial marker as branched acids. Composition of TAG followed closely the changes in trophic interactions as diatom and flagellate markers dominated in spring and summer while bacterial and detritus particle markers dominated in late winter. The composition of wax esters followed the same seasonal succession but with a lower level of turn over time and shifted characteristics (bacterial markers) from winter to spring individuals when compared to TAG. Ontogenetic changes showed high triacylglycerols content in younger C3 stages and increasing wax esters with increasing developmental stages. Fatty acid composition of PL showed low percentages of EPA and DHA in stage C3, and recovery of high levels of DHA for stage C4 or 20:5n-3 (EPA) at stage C5. The same trend was observed for 18:4n-3. The reverse pattern was noted for the n-6 polyunsaturated acids (PUFA) suggesting a greater requirement in younger stages. Fatty acid partitioning between neutral and PL suggested essential fatty acids selective incorporation from neutral classes into membrane lipids.
Frontiers in Marine Science, 2022
Consumer regulation of lipid composition during assimilation of dietary items is related to their ecology, habitat, and life cycle, and may lead to extra energetic costs associated with the conversion of dietary material into the fatty acids (FAs) necessary to meet metabolic requirements. For example, lipid-rich copepods from temperate and polar latitudes must convert assimilated dietary FAs into wax esters, an efficient type of energy storage which enables them to cope with seasonal food shortages and buoyancy requirements. Lipidpoor copepods, however, tend to not be as constrained by food availability as their lipidrich counterparts and, thus, should have no need for modifying dietary FAs. Our objective was to test the assumption that Temora longicornis, a proxy species for lipid-poor copepods, does not regulate its lipid composition. Isotopically-enriched (13 C) diatoms were fed to copepods during a 5-day laboratory experiment. Compound-specific stable isotope analysis of algae and copepod samples was performed in order to calculate dietary FA assimilation, turnover, and assimilation efficiency into copepod FAs. Approximately 65% of the total dietary lipid carbon (C) assimilated (913 ± 68 ng C ind-1 at the end of the experiment) was recorded as polyunsaturated FAs, with 20 and 15% recorded as saturated and monounsaturated FAs, respectively. As expected, T. longicornis assimilated dietary FAs in an unregulated, non-homeostatic manner, as evidenced by the changes in its FA profile, which became more similar to that of their diet. Copepods assimilated 11% of the total dietary C (or 40% of the dietary lipid C) ingested in the first two days of the experiment. In addition, 34% of their somatic growth (in C) after two days was due to the assimilation of dietary C in FAs. Global warming may lead to increased proportions of smaller copepods in the oceans, and to a lower availability of algae-produced essential FAs. In order for changes in the energy transfer in marine food webs to be better understood, it is important that future investigations assess a broader range of diets as well as lipid-poor zooplankton from oceanographic areas throughout the world's oceans.
Exceptional lipid storage mode of the copepod Boeckella poopoensis in a pampean salt lake, Argentina
Aquatic Biology, 2012
The lipid biochemistry of zooplankton was investigated in Lake Chasico, a pampean salt lake in Argentina. The lipid biomass of the zooplankton community was dominated by the calanoid copepod Boeckella poopoensis. The major storage lipids during winter were wax esters and triacylglycerols, which reached up to 59 and 37% of the total lipids, respectively. A striking feature of the zooplankton fatty acid composition was the extraordinarily high level of 18:4(n-3) and 20:4(n-3) fatty acids, the highest ever reported for the latter in zooplankton. During winter, 20:4(n-3) accounted on average for 20% of the total fatty acids in the wax ester fraction and 7% in the triacylglycerols. The close relationship (r = 0.83, p < 0.001) between the 2 fatty acids implies the biosynthesis of 20:4(n-3) in B. poopoensis by chain elongation of 18:4(n-3), a dietary precursor and flagellate marker. The accumulation of 20:4(n-3) may be also partially related to B. poopoensis grazing on heterotrophic protozoa or non-flagellated chlorophytes, although this fatty acid was almost absent in the seston fraction. In summer, wax esters were slightly lower (45%), compensated by higher phospholipid levels. The 16:0 fatty alcohol moiety was predominant in the wax esters of all samples, corroborating the opportunistic feeding behavior of B. poopoensis. The high amounts of wax esters in zooplankton are typical of marine species, suggesting that the wax ester biosynthesis of B. poopoensis and the extraordinary fatty acid composition are adaptations to the unstable environmental conditions of salt lakes.
Marine Biology, 2004
To discern species-specific patterns in omnivory indices in copepods from the North Water Polynya, lipid classes and fatty acids were determined in Calanus hyperboreus Krøyer copepodite stage 5 (CV), C. glacialis Jaschnov (CV) and Metridia longa Lubbock (females) sampled below the mixed layer during autumn 1999. Generally, M. longa contained higher proportions of triacylglycerols, polar lipids and 18:1(n-9) than the other species. M. longa also had lower relative amounts of wax esters (WE), polyunsaturated fatty acids (PUFA), 20:1(n-9), 22:1(n-11), and lower absolute (lg lipid copepod-1) and relative (% lipid) lipid levels. Unsaturation coefficients (UC; ratio of polyunsaturated to total WE) were usually lowest in M. longa. These differences probably relate to a lesser dependence on phytoplankton in M. longa, and hence more ingestion of PUFA-poor prey. Moreover, levels of the carnivory index 18:1(n-9)/18:1(n-7) were highest in M. longa. Our data support the widespread contention that M. longa is more omnivorous than C. hyperboreus and C. glacialis. Proportions of bacterial fatty acids [odd-numbered and/or branched (OBFA); 18:1(n-7)] and PUFA/SFA (SFA: saturated fatty acids) ratios were largely unrelated to feeding strategy. Relationships between relative and absolute amounts of 16:1(n-7) and 18:1(n-7) in copepods suggest that the latter fatty acid is formed in vivo by chain elongation of the former. However, elevated levels of 18:1(n-7) and OBFA in M. longa at stations dominated by the microbial loop imply that these indices can be used to track ingestion of PUFA-poor protozoans when diatoms are scarce.
Journal of The Chilean Chemical Society, 2009
This work presents the fatty acid composition of copepod species in southern Chile: two of them that are ectoparasites on Eleginops maclovinus (Caligus rogercresseyi and Lepeophtheirus mugiloidis) and one free-living species (Tigriopus sp.). C. rogercresseyi females from different hosts (Salmo salar and E. Maclovinus). Fatty acid methyl esters were determined with GC-MS. The studied species presented a wide variety of saturated, monounsaturated, and polyunsaturated fatty acids, with compounds having from 12 to 24 carbons. The studied species had different percentage compositions of the acids identified. In all three species, palmitic (C 16) and oleic (C 18:1) fatty acids dominated the percentage concentrations. The highest percentage concentration (46.59 %) was found for palmitic acid in Tigriopus. Only the females of C. rogercresseyi analyzed were found to have myristoleic acid (C 14:1). Stearic (C 18) and oleic (C 18:1) acids were present in both C. rogercresseyi males and females, but with different distributions. Oleic acid in females was 33.97 % and only 7.64 % in males, whereas stearic acid was 9.95 % in females and 21.51 % in males. The C. rogercresseyi on Patagonian blennie (Eleginops maclovinus) revealed 3.89% C 20:4 and 9.60 % C 20:5. Eicosapentaenoic and docosahexaenoic acids, detected only in the ectoparasitic copepods, had percentage concentrations of up to 10 %. The possible role of this fatty acid in the stimulation of innate fish immunity is discussed.
Polar Biology, 2003
The fatty acid and alcohol compositions of the Antarctic copepods Oithona similis, Oncaea curvata, Oncaea antarctica and the Arctic Oncaea borealis were determined to provide the first data on their lipid biochemistry and to expand the present knowledge on their feeding modes and life-cycle strategies. All these tiny species contained high amounts of wax esters (on average 51.4-86.3% of total lipid), except females of Oithona similis (15.2%). The fatty-acid composition was clearly dominated by 18:1(n-9), especially in the wax-ester-rich Oncaea curvata (79.7% of total fatty acids). In all species, 16:0 and the polyunsaturated fatty acids 20:5(n-3) and 22:6(n-3), which are structural components of all membranes, occurred in significant proportions. The dominant fatty alcohols were 14:0 and 16:0. In Oncaea antarctica and Oncaea borealis, the 20:1(n-9) and 22:1 (n-11) alcohols and, to a lesser extent, the corresponding fatty acids were also found in high proportions. This indicates carnivorous feeding, although de novo biosynthesis cannot be excluded. The variable composition might be due to a wider range of food items and parasitic feeding. Typical trophic marker fatty acids for phytoplankton ingestion occurred only in small amounts, which suggests that the species were feeding on particles such as detritus or aggregates and not on living phytoplankton. From the compositional data of fatty acids and alcohols, it can be concluded that feeding behaviour of all species is omnivorous and/or carnivorous.
Marine Biology, 2004
Many free-living copepods produce and store lipids prior to entering diapause (long-term dormancy). Heteropsyllus nunni Coull is the only marine harpacticoid copepod known to undergo any form of diapause. This study presents the first information on the types of lipids and fatty acids produced for long-term diapause in this benthic species. Sexually immature adults of H. nunni undergo diapause within a pliable self-made cyst. Prior to entering diapause (which lasts 3-4 months), they produce and store large amounts of orange lipid. The lipids apparently are utilized during diapause. Although some residual lipids remain, chiefly around the gonads, after the copepods emerge from their cysts, the lipid stores are visibly reduced. Typically, the copepods mate and produce eggs within 48 h after diapause is terminated. Light level and confocal laser scanning microscopy revealed that the lipid stores are distributed throughout the body in numerous oil droplets and not as a single oil sac, as seen in many marine calanoid copepods prior to overwintering (winter diapause). Transmission electron microscopy showed lipid spheres within the gut epithelium and large droplets of lipids stored extracellularly. Confocal laser scanning microscopy of copepods in pre-diapause, during diapause (encysted), post-diapause (recently excysted), and in reproductive condition, revealed that lipid stores are reduced following diapause, but are not totally absent. Analysis of lipid classes showed that H. nunni store predominantly wax esters/sterol esters (83% of total lipids) during diapause. The predominant lipid is most likely wax esters, as sterol esters typically are found only in small amounts in copepods. Fatty acid (FA) profiles of the copepods in diapause showed 16:0 to be most abundant followed by 16:1n-7 and 18:0; other FA occurred at concentrations <10% of total FA. Three polyunsaturated fatty acids (PUFA), 20:5n-3, 18:2n-6 and 20:4n-6, were found at concentrations <2% of total FA. These PUFA are ''essential fatty acids'' in H. nunni, obtained through dietary sources. The lipid classes and fatty acids present in H. nunni during diapause are compared to those of other copepods, some in a state of diapause and others not. It appears that lipid class and FA profiles are indicative of genetic makeup, type of diet or amount of food consumed prior to dormancy. Some classic paradigms of lipids and their association with copepod diapause are re-evaluated.