Fatty Acids In Hepatopancreas Research Articles

Dietary choline activates the Ampk/Srebp signaling pathway and decreases lipid levels in Pacific white shrimp (Litopenaeus vannamei)

An 8-week feeding trial was conducted in Pacific white shrimp (Litopenaeus vannamei) to evaluate the effects of dietary choline supplementation on choline transport and metabolism, hepatopancreas histological structure and fatty acid profile, and regulation of lipid metabolism. Six isonitrogenous and isolipidic diets were formulated to contain different choline levels of 2.91 (basal diet), 3.85, 4.67, 6.55, 10.70 and 18.90 g/kg, respectively. A total of 960 shrimp (initial weight, 1.38 ± 0.01 g) were distributed randomly into twenty-four 250-L cylindrical fiber-glass tanks, with each diet assigned randomly to 4 replicate tanks. The results indicated that dietary choline significantly promoted the deposition of choline, betaine and carnitine (P < 0.05). The diameters and areas of R cells, total lipid and triglyceride contents in hepatopancreas, and triglyceride and non-esterified fatty acid contents in hemolymph were negatively correlated with dietary choline level. The contents of functional fatty acids in hepatopancreas, the activity of acetyl-CoA carboxylase (Acc), and the mRNA expression of fas, srebp and acc were highest in shrimp fed the diet containing 4.67 g/kg choline, and significantly higher than those fed the diet containing 2.91 g/kg, the lowest level of choline (P < 0.05). The number of R cells, content of very low-density lipoprotein (VLDL), activities of carnitine palmitoyl-transferase (Cpt1), lipoprotein lipase and hepatic lipase, and the mRNA expression levels of cpt1, fabp, fatp, ldlr, and ampk in hepatopancreas increased significantly as dietary choline increased (P < 0.05). In addition, hepatopancreas mRNA expression levels of ctl1, ctl2, oct1, badh, bhmt, ck, cept, and cct were generally up-regulated as dietary choline level increased (P < 0.01). In conclusion, dietary choline promoted the deposition of choline and its metabolites by up-regulating genes related to choline transport and metabolism. Moreover, appropriate dietary choline level promoted the development of hepatopancreas R cells and maintained the normal accumulation of lipids required for development, while high dietary choline not only promoted hepatopancreas lipid export by enhancing VLDL synthesis, but also promoted fatty acid β-oxidation and inhibited de novo fatty acid synthesis by activating the Ampk/Srebp signaling pathway. These findings provided further insight and understanding of the mechanisms by which dietary choline regulated lipid metabolism in L. vannamei.

Dietary cholesterol promotes growth and ecdysone signalling pathway by modulating cholesterol transport in swimming crabs (Portunus trituberculatus).

Cholesterol, as an indispensable nutrient, regulates molting and growth in crustacean. As crustaceans are unable to biosynthesize cholesterol de novo, it is central to understand how dietary cholesterol affects molting in crustaceans. An 8-week feeding trial was conducted to evaluate the effects of dietary cholesterol level (0.12%, 0.43%, 0.79%, 1.00%, 1.30% and 2.50%) on growth, cholesterol metabolism and expression of genes related to lipid and ecdysone metabolism in female swimming crabs (Portunus trituberculatus). A total of 192 crabs (1.41 ± 0.05 g) were randomly distributed into 192 aquaria. Each treatment had 4 replicates with each replicate containing 8 crabs. Crabs fed the 1.00% cholesterol diet showed best growth performance, and thus based on percent weight gain, the optimal dietary cholesterol requirement was calculated at 1.01%. Tissue cholesterol concentrations were positively correlated with dietary cholesterol level. The contents of functional fatty acids in hepatopancreas significantly increased as dietary cholesterol increased from 0.12% to 2.50% (P < 0.05). The expression levels of genes related to lipogenesis pathway, lipid catabolism and fatty acid oxidation were significantly down-regulated with increased dietary cholesterol level (P < 0.05). The highest expression levels of cholesterol transport genes, low-density lipoprotein receptor (ldlr) and low-density lipoprotein receptor-related protein 2 (lrp2) occurred in crabs fed the 1.30% cholesterol diet. Moreover, hormones related to molting such as crustacean hyperglycemic hormone (CHH), methyl farnesoate (MF), molt-inhibiting hormone (MIH), and ecdysone in hemolymph were significantly influenced by dietary cholesterol level (P < 0.05). The highest expression levels of ecdysone receptor (ecr) and chitinase 1 (chi1) in eyestalk and hepatopancreas were found in crabs fed the diet containing 1.00% cholesterol (P < 0.05). In conclusion, the optimal dietary level was beneficial to functional fatty acid accumulation, regulated lipid metabolism, promoted the ecdysone signalling pathway by improving the cholesterol transport, and improved the molting rate and growth of swimming crabs.

Effects of Dietary Phospholipid and Cholesterol Levels on Growth, Molting Performance, and Ovary Development in Female Juvenile Crayfish (Procambarus clarkii)

The interaction between phospholipid (PL) and cholesterol (CH) on growth performance, molting rate, hepatopancreas fatty acid composition, and ovary development of the female red swamp crayfish (Procambarus clarkii) was investigated. Nine diets containing three PL levels (0, 20, and 60 g/kg) and three CH levels (0, 5, and 10 g/kg) were included in the study. Female crayfish (initial weight: 5.92 ± 0.03 g) were reared for 60 days. There was no significant interaction between dietary PL and CH levels ( P &gt; 0.05 ). However, the best growth performance and ovarian development were observed in crayfish receiving the 60 g/kg PL and 10 g/kg CH diet. High PL levels promoted CH transport in the hepatopancreas, and long-chain unsaturated fatty acid (C20:4n-6, C20:5n-3, and C22:6n-3) content of the hepatopancreas increased with the addition of PL in the diet. The molting rate increased with increasing CH levels in the diet containing 60 g/kg PL. Real-time quantitative polymerase chain reaction revealed that dietary CH enhanced the molting rate by improving the ecdysone receptor genes at transcription. This study showed that crayfish fed a diet containing 10 g/kg CH and 60 g/kg PL obtained maximum growth, molting rate, and ovary development.

Aurantiochytrium sp. Meal Improved Body Fatty Acid Profile and Morphophysiology in Nile Tilapia Reared at Low Temperature

Aurantiochytrium sp. is a heterotrophic microorganism that produces docosahexaenoic acid (DHA), thus being considered as a possible replacement for fish oil in aquafeeds. We investigated the effect of Aurantiochytrium sp. meal (AM) dietary levels (0, 5, 10, 20, and 40 g kg−1) on Nile tilapia body and hepatopancreas fatty acid (FA) profile, body FA retention, somatic indices, and morphophysiological changes in the intestine and hepatopancreas, after feeding Nile tilapia juveniles (average initial weight 8.47 g) for 87 days at 22 °C. The 10AM diet was compared to a control diet containing cod liver oil (CLO), since their DHA concentration was similar. Within fish fed diets containing increasing levels of AM, there was a linear increase in n-3 FA content, especially DHA, which varied in the body (0.02 to 0.41 g 100 g−1) and hepatopancreas (0.15 to 1.05 g 100 g−1). The morphology of the intestines and hepatopancreas was positively affected in AM-fed fish. Fish fed 10AM showed less accumulation of n-3 FAs in the body and hepatopancreas when compared to fish fed CLO. Therefore, AM is an adequate substitute for fish oil in winter diets for Nile tilapia, with the supplementation of 40AM promoting the best results regarding intestine and hepatopancreas morphophysiology.

Lipidomic profiling reveals molecular modification of lipids in hepatopancreas of juvenile mud crab (Scylla paramamosain) fed with different dietary DHA/EPA ratios

Untargeted lipidomic analysis was conducted to explore how different dietary docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) ratio and, specifically, how an optimal ratio (2.3) compared to a suboptimum ratio (0.6) impacted lipid molecular species and the positional distribution of fatty acids in hepatopancreas of mud crab. The results indicated that major category of lipid affected by dietary DHA/EPA ratio was glycerophospholipids (GPs). The optimum dietary DHA/EPA ratio increased the contents of DHA bound to the sn-2 and sn-3 positions of phosphatidylcholine (PC) and triacylglycerol, EPA bound to the sn-2 position of phosphatidylcholine and 18:2n-6 bound to the sn-2 position of phosphatidylethanolamine (PE). Increased dietary DHA/EPA ratio also led to competition between arachidonic acid (ARA) and 18:2n-6 bound to esterified sites. Appropriate dietary DHA/EPA ratio can not only improve the growth performance and nutritional quality of mud crab, but also provide higher quality products for human consumers.

Changes in bud morphology, growth-related genes and nutritional status during cheliped regeneration in the Chinese mitten crab, Eriocheir sinensis.

During pond culture of Eriocheir sinensis, a high limb-impairment rate restricts the industry development and quality. Therefore, research on limb autotomy and regeneration has important practical significance for the industrial development and basic biology of E. sinensis. This study evaluated the changes in bud morphology, growth-related gene expression and nutritional status during cheliped regeneration in E. sinensis. The study found that the new cheliped was pre-formed in the bud and then regenerated with the completion of molting of E. sinensis. The new cheliped was similar in morphology to the normal cheliped after the first molting but smaller in size. The qRT-PCR results of growth-related genes showed that the expression levels of EcR-mRNA (ecdysteroid receptor) and Chi-mRNA (chitinase) were significantly up-regulated, whereas the expression of MIH-mRNA (molt-inhibiting hormone) was significantly down-regulated (P < 0.05). The nutritional status during the regeneration process showed that the hepatopancreas total lipid content decreased significantly within 28 days and was significantly lower in the autotomy group than in the control group at 14 d and 21 d (P < 0.05). The hepatopancreas fatty acid composition results showed that saturated fatty acids (SFA), highly unsaturated fatty acids (HUFA) and n-3/n-6 were significantly higher in the autotomy group than in the control group at 21 d (P < 0.05), whereas the ∑ n-6 PUFA and ∑ n-3 PUFA at 1 d and 7 d, and the monounsaturated fatty acid (MUFA) at 28 d in the autotomy group were significantly lower than in the control group (P < 0.05). Moreover, the levels of eicosatetraenoic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) showed that DHA was significantly lower at 7 d and significantly higher at 21 d in the autotomy group than in the control group (P < 0.05), whereas ARA and EPA were not significantly different between the two groups. Muscle L-tryptophan content was significantly lower at 1 d and significantly higher at 7 d in the autotomy group than in the control group (P < 0.05). These results indicate that during the cheliped regeneration process, crabs could accelerate molting and regeneration by regulating growth-related gene expression (e.g., EcR-mRNA and MIH-mRNA) and nutrient metabolism (e.g., lipid metabolism).

Effects of the complete replacement of fish oil with linseed oil on growth, fatty acid composition, and protein expression in the Chinese mitten crab (Eriocheir sinensis)

BackgroundThe finite marine resources make it difficult for us to obtain enough fish oil (FO) used in aquatic feeds. Another sustainable ingredients should be found to substitute FO. The effects of replacing FO with vegetable oil have been studied in a variety of crustaceans, but most studies have focused on the phenotypic effects. Little is known about the mechanisms of the effects.MethodsTo understand the molecular responses during the replacement of FO in Eriocheir sinensis, we investigated the effects of feeding FO or linseed oil (LO) on growth performance, digestive enzyme activity, fatty acid composition and protein expression in E. sinensis. Twenty-four juvenile crabs were fed diets containing FO or LO for 112 days. Weight, carapace length and width were recorded. Fatty acid composition of the diets and the hepatopancreas and protein expression in the hepatopancreas were analyzed.ResultsGrowth performance and molting interval were unchanged by diet. Crabs fed FO and LO had same activity of lipase and amylase, but comparing with crabs fed LO, crabs fed FO had higher trypsin activity and lower pepsin activity. Hepatopancreas fatty acid composition changed to reflect the fatty acid composition of the diets. In total, 194 proteins were differentially expressed in the hepatopancreas between the diets. Expression of heat shock proteins was higher in crabs fed LO. Expression of fatty acid synthase, long-chain fatty acid transport protein 4, acyl-CoA delta-9 desaturase, and fatty acid-binding protein 1, was higher in crabs fed FO.ConclusionsThe substitution of FO with LO didn’t have any effects on the growth and molting of mitten crab, but could significantly decrease the ability of mitten crab to cope with stress. The high content of HUFAs in the hepatopancreas of mitten crab fed FO is due to the high abundance of the proteins relative to the transport of the HUFAs. These findings provide a reason of the high content of EPA and DHA in crabs fed with FO, and provide new information for the replacement of FO in diets of mitten crab.

Effects of dietary biotin on growth performance and fatty acids metabolism in blunt snout bream, Megalobrama amblycephala fed with different lipid levels diets

A 2×2 factorial design was conducted to elucidate the effect of dietary biotin on growth performance, body composition, tissue lipid content and lipid metabolism related genes expression of blunt snout bream, Megalobrama amblycephala fed with different dietary lipid levels. Juvenile fish (average initial weight: 36.0±1.0g) were fed with diets containing two lipid levels (5% and 11%) and two biotin levels (0.06mgkg−1 and 2.50mgkg−1) for 8weeks, respectively. Specific growth rate (SGR), hepatosomatic index (HSI), mesenteric fat index (MFI), hepatopancreas lipid, total triacylglycerol (TG) and cholesterol (TC) contents, plasma TG and muscle TG contents were significantly (P<0.05) affected by dietary lipid. No significant interactions between lipid and biotin were observed. Significant (P<0.05) interactions between lipid and biotin were observed in muscle lipid, hepatopancreas saturated fatty acids (SFA) and muscle EPA contents. Hepatopancreas monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA) and EPA+DHA contents were significantly (P<0.05) affected by dietary biotin. At dietary lipid levels of 5 or 10%, hepatopancreas MUFA contents were decreased but PUFA and EPA+DHA contents were increased significantly (P<0.05) with dietary biotin levels increase. Significant (P<0.05) interaction between lipid and biotin were also observed in hepatopancreas acetyl-CoA carboxylase α (ACCα), sterol regulatory element-binding protein 1 (SREBP1), acyl-CoA oxidase (ACO) and acyl-CoA oxidase (FACS) genes expression levels. ACCα, fatty acid synthetase (FAS), liver X receptor α (LXRα), SREBP1, ACO and FACS genes expression levels significantly (P<0.05) increased with the increasing dietary biotin levels. ACCα, peroxisome proliferatoractivated receptor α (PPARα), carnitine palmitoyltransferase I(CPTI) and ACO genes expression levels significantly (P<0.05) decreased with the increasing dietary lipid levels. In conclusion, no effects of biotin on growth performance, body parameter, whole-body composition in fish fed with 5% or 11% lipid diets were found. Dietary biotin could play a role in hepatopancreas fatty acid synthesis and β-oxidation related genes expression. Dietary biotin could promote hepatopancreas polyunsaturated fatty acids synthesis of fish.

Effects of dietary phosphatidylcholine (PC) levels on the growth, molt performance and fatty acid composition of juvenile swimming crab, Portunus trituberculatus

A 50-day feeding trial was conducted to investigate the effects of dietary phosphatidylcholine (PC) levels on the growth performance, molt and body composition of the juvenile swimming crab, Portunus trituberculatus. Four isonitrogenous purified casein-based diets containing three PC levels and one commercial crude soybean lecithin (SL) level were formulated. A PC-deficient diet was designed as a control diet. Each diet was given to triplicate groups of 15 P. trituberculatus (initial weight, 25.4±0.1g/crab). The occurrence of molt death syndrome (MDS) was lowest in crabs fed the diet with 20g/kg PC. The growth of crabs showed a significant positive correlation with dietary PC level, increasing linearly with PC level (P<0.05), while growth performance was not significantly affected by SL supplementation. The highest growth performance was obtained in crabs fed the diet with 20g/kg PC. Whole body triglyceride and cholesterol levels also increased linearly with increasing dietary PC level (P<0.05). Serum triglyceride levels were significantly increased with SL supplementation (P<0.05). Our results show that the n-3/n-6 ratios and 22:6n-3 concentrations in both hepatopancreas and muscle increased significantly with SL addition (P<0.05). This study shows that PC supplementation in a casein-based diet had a significant growth-promoting effect on P. trituberculatus. Moreover, dietary SL had a greater effect on muscle and hepatopancreas fatty acid profiles than purified PC supplementation in diets.

Seasonal variations in free amino acids, nucleotide-related compounds, and fatty acids and meat yield of the coconut crab Birgus latro

This study analyzed seasonal variations in meat yield and compositions of free amino acids (FAA), nucleotide-related compounds (NRC), and fatty acids in muscle and hepatopancreas of the coconut crab Birgus latro of Okinawa, southwest Japan. A conspicuous increase in total meat yield was observed during September to November, prior to molting in the winter dry season. Although both total FAA and NRC content in muscle and hepatopancreas did not vary significantly by seasons, the taste activity value of methionine in muscle was larger than 1 only during September to November. Seasonal variations in equivalent umami concentration (EUC) were greater in muscle than in the hepatopancreas, with the EUC of muscles highest in September to November. Although fatty acid compositions of muscle and hepatopancreas did not change significantly seasonally, amounts of total fatty acids, saturated fatty acids, and monounsaturated fatty acids in muscle and hepatopancreas, and amount of n-3 polyunsaturated fatty acids in the hepatopancreas, were significantly greater in September to November. These results indicate the best season to eat coconut crab is September to November. These findings may contribute to a premium value for this resource and promote resource conservation of this species.

Biochemical composition dynamics of the ovaries and hepatopancreas at different physiological stages of the female marine crab, Charybdis japonica

The present study investigated the biochemical composition, including the amino acids and fatty acids profiles of the ovaries and hepatopancreas of the female marine crab, Charybdis japonica (A. Milne-Edwards, 1861), at different physiological stages (immature, mature, spawning and abortion), together with the dynamic changes of the Gonadosomatic Index (GSI) and Hepatosomatic Index (HSI) during gonad development. A significant inverse relationship between GSI and HSI (R=−0.82; P<0.05) was recorded. The protein, total amino-acid (TAA), essential amino acid (EAA) and polyunsaturated fatty acid (PUFA) content and the ratio of n-3/n-6 in the ovaries were significantly higher than those in the hepatopancreas, while the content of moisture and saturated fatty acid (SFA) were lower. From immature to mature, the content of proteins and lipids in ovaries increased, and the content of carbohydrates decreased noticeably, while these tendencies in hepatopancreas were in the reverse order. A significant increase in the total amount of TAA and EAA in ovaries of mature stages was measured; the content of all amino acids increased, except for arginine, which decreased slightly. The content of PUFA in the ovaries increased with maturation, while the content of monounsaturated fatty acid (MUFA) decreased. Abundant threonine, methionine, leucine and C22:6n-3 (docosahexaenoic acid, DHA) were observed in the hepatopancreas of spawning crabs. Compared to spawning crabs, the content of protein and ash in the hepatopancreas of aborting crabs decreased significantly, while the carbohydrates content rose, and that the content of TAA, EAA and PUFA in the ovaries and hepatopancreas of aborting crabs were all lower, especially the amount of n-3 fatty acids in hepatopancreas, which decreased substantially, including DHA from 9.02% to 3.25%, and eicosapentaenoic acid (EPA) from 0.93% to 0.44%.

The effect of dietary zinc supplementation on the growth, hepatopancreas fatty acid composition and gene expression in the Chinese mitten crab, Eriocheir sinensis (H. Milne-Edwards) (Decapoda: Grapsidae)

In order to determine the minimal dietary zinc (Zn) requirements in the Chinese mitten crab, Eriocheir sinensis, we assessed the influence of dietary Zn levels on the weight gain, survival, fatty acid composition, expressions of fatty acid-binding protein (FABP) and metallothionein-1 (MT-1) transcripts at end of an 8-week feeding regime. Supplemental Zn (0, 10, 20, 40 and 80 mg kg−1 diet) was administered orally to crabs via the diet. The results indicate that dietary supplementation of 20 mg Zn kg−1 diet yielded the largest weight gain. While the hepatopancreatic concentrations of Zn increased progressively with the supplemental dosage, the hepatopancreas fatty acid composition was variable and dependent on supplementation. As the dietary Zn concentrations increased, 18:0 in crab hepatopancreas exhibited a downward trend, whereas 18:1 n-9, 18:3 n-3, 20:4 n-6 ( arachidonic acid,ARA) and 22:6 n-3 (docosahexaenoic acid, DHA) compositions exhibited a bell-curve response. The expressions of FABP and MT-1 transcripts were the highest in crabs receiving 20 or 40 mg Zn kg−1 diet corresponding to quantified levels of 27 or 44 mg Zn kg−1 diet. Taken together, these results suggest that dietary Zn deficiency may influence the synthesis and metabolism of fatty acids in the hepatopancreas of the mitten crab, an important aquaculture species.

Fatty acid composition and analysis of freshwater caridean shrimp Macrobrachium nipponense (De Haan) during spermiogenesis

We analysed fatty acids (FAs) composition and the potential functions of FAs in hepatopancreas and testis of freshwater caridean shrimp Macrobrachium nipponense during testis development. The hepatopancreas presented a high unsaturated FA content of about 40%, whereas the testis showed a high level of saturated fatty acids (SFAs) with a decreasing content of 97^86% of total FAs during maturation. Several speci¢c FAs in testis showed signi¢cant changes throughout maturation. Among SFAs, C14:0 contributed with a relatively constant high proportion of about 22%, whereas C16:0 and C18:0 contents were also at high levels but showed signi¢cant increases during maturation. Representatives of highly unsaturated fatty acids (HUFAs), such as C18:1n-9, C18:2n-6, C20:5n-3 (EPA), C20:4n-6 (AA) and C22:6n-3 (DHA) showed signi¢cant increases despite their low proportion in the gonad. These results suggest that a high content of HUFAs in hepatopancreas may represent a reservoir for sperm production. The FA C14:0 may provide a particular function. The variations of the FA pro¢le in testis at diierent developmental stages reveals that C18:1n-9, C18:2n-6, C20:5n-3, C20:4n-6 and C22:6n-3 may play important roles in spermiogenesis.

Influence of highly unsaturated fatty acids on the responses of white shrimp ( Litopenaeus vannamei) postlarvae to low salinity

Salinity stress tests are commonly applied in shrimp hatcheries to estimate the quality of postlarvae (PL) to be used during growout. Higher larval survival during culture and to a salinity stress test in both fish and crustaceans have been reported when specimens were offered a diet containing high levels of highly unsaturated fatty acids (HUFA). However, it is not clear if increased survival is a result of better overall physiological condition resulting from the diet or a specific effect of HUFA on osmoregulatory mechanisms. This study analyzed if HUFA-rich diets could modify the fatty acid composition of membranes in gills, and if this change in composition could affect the activity of the Na +/K + ATPase pump and carbonic anhydrase in relation to changes in salinity. One-day-old postlarvae (PL1) pooled from different spawns were fed for 20 days with Artemia sp. nauplii enriched with three levels of HUFA: low, medium and high. At PL20, survivals during culture and to salinity stress test (tap water for 30 min) were evaluated. Also at this stage, Na +/K +-ATPase and carbonic anhydrase activity, morphometric variables, and fatty acid composition in the hepatopancreas and gills were measured after they were submitted to a salinity challenge in dilute seawater (10 ppt) for 3 h. No significant differences were observed in survival rates during culture, but survival to a salinity stress test was higher and gill area was larger in PL20 fed the Artemia sp. nauplii enriched with medium HUFA levels, probably as a result of an increased 22:6n-3 content and higher 22:6n-3/20:5n-3 ratio in this diet and in the tissues of the organisms fed this diet. Na +/K +-ATPase specific activity was significantly higher in posterior gills, while the specific activity of the carbonic anhydrase was higher in anterior gills. Enzymatic activities increased significantly in PL20 submitted to a salinity challenge, and HUFA levels in the diet affected both. The proportion of fatty acids in hepatopancreas and gills were significantly affected not only by diet, but also by exposure to dilute media. This effect is discussed in relation to an increase in gill surface and changes in fatty acid composition in the phospholipids present in gill membranes, which can modify the permeability and the activity of the Na +/K +-ATPase pump. The beneficial effect of HUFA supplementation in the diet on survival to salinity stress test is partially related to modification of fatty acid composition of gills and to a larger gill area, which in turn enhances osmoregulatory mechanisms, namely Na +/K +-ATPase and carbonic anhydrase activities.

Seasonal variations in hepatopancreas fatty acid profiles of two colour forms of shore crabs, Carcinus maenas

The relationship between intermoult duration (coloration), sex, size and seasonal variations in fatty acid (FA) profiles was studied in a population of shore crabs, Carcinus maenas, inhabiting the Isefjord, Denmark. For male shore crabs, the total hepatopancreas FA content was high in July and December (12.7 to 16.0 mg g−1 dry weight, dw) but lower in May and September (7.3 to 10.0 mg g−1). This indicates that male shore crabs are in relatively good condition before winter, when the crabs migrate off shore, but in relatively poor condition when they return to shallow waters during spring. The hepatopancreas FA content also decreased over the mating season. After the mating season the hepatopancreas FA content of males had decreased to approximately 60% of that prior to the mating season. Female shore crabs had significantly higher hepatopancreas FA levels than males in May (11.7 mg g−1 dw), September (12.6 mg g−1 dw) and December (17.9 mg g−1 dw) but lower levels in July (9.5 mg g−1 dw). This indicates that the spawning season is the most energy-demanding part of the female reproductive cycle. For all seasons, the hepatopancreas FA content of green shore crabs was significantly higher than that of red shore crabs. For both colour forms, the amount of polyunsaturated fatty acids (PUFAs) was significantly higher than that of saturated fatty acids (SAFAs) and monounsaturated fatty acids (MUFAs), with the relative proportion of PUFAs increasing when the total hepatopancreas FA content decreased. For both genders and colour forms, the most dominating SAFA was palmitic acid (16:0). Palmitoleic acid (16:1ω7), vaccenic acid (18:1ω7) and oleic acid (18:1ω9) were the three MUFAs found in highest concentrations. The most dominating PUFA was eicosapentaenoic acid (EPA, 20:5ω3). Docosahexaenoic acid (DHA, 22:6ω3) and arachidonic acid (AA, 20:4ω6) were also abundant in all samples. The results demonstrated that season, sex, size and intermoult duration all influence the amount of FAs present in the hepatopancreas of shore crabs.

Fatty acids in the hepatopancreas, ovaries and embryos of the spider crab Libinia emarginata during the reproductive cycle

Summary Gas chromatographic analysis of fatty acids was carried out on female juvenile spider crab tissues (ovary and hepatopancreas), and tissues from reproductively active adult females (embryo, ovary and hepatopancreas). Six acids (16:0, 16:1, 18:0, 18:1, 20:5, and 22:6) each constantly made up at least 5.0% of the total acid profile, and in the embryos 14:0 was also common. There were 17 significant n-6 and n-3 acid regression coeffiecients, of which 15 were positive; the only two negative correlations were both in embryonic tissues (22:2 and 20:4) and (22:5 and 20:5). Hierarchical cluster analysis of adult crabs showed that ovary and hepatopancreas fatty acid patterns were similar, while embryonic tissue is somewhat distinct.

Fatty Acid Synthesis in Aquatic Animals and Its Metabolism in Carp, Cyprinus cardo

Lipid metabolism and its regulation in aquatic organisms seed to differ considerably from those in mammals. In our experiments, carp starved for 10 days or fed fat-free diet for 35 days had almost the same hepatopancreas acetyl CoA carboxylase (ACC) specific activity levels as the controls. On supplementing the fat-free diets with 5% fatty acid, there was no depression of the specific activity of carp hepatopancreas ACC. The administration of a fat-free diet for 35 days resulted in increased specific activity of hepatopancreas fatty acid synthetase (FAS) and supplementing it of with 5% fatty acid decreased the specific activity of carp hepatopancreas FAS. An injection insulin or alloxan had no effect on the specific activity of carp hepatophacreas ACC or FAS. The activation of ACC from aquatic organisms required citrate and Mg2+ and that of FAS required NADPH, as is also the case in mammals. In carp hepatopancreas, the specific activity of ACC was 45mol/min/mg protein and that of FAS, 421pmol/min/mg protein. Both these values are low compared to those in mammals. In another aquatic 7 species tested, the specific activity of lipogenic enzymes was about one tenth that in carp hepatopancreas though crude enzymes prepared from whole body were examined. The present data indicate that lipogenesis in fish, and other aquatic organisms is apparently in a reduced state.