Effects Of Dietary Lipid Levels Research Articles

Effects of dietary lipid level on growth performance, body composition and digestive enzymes activity of juvenile sea cucumber,Apostichopus japonicus

A feeding trial aimed to determine the effects of dietary lipid level on growth performance, body composition and digestive enzymes activity of juvenile sea cucumber, Apostichopus japonicus. Diets with six crude lipid levels (1.9, 13.8, 29.1, 43.6, 59.6 and 71.6 g kg−1) were fed to sea cucumbers (initial weights 0.65 ± 0.01 g) at a density of 30 juveniles, once a day. After 60 days, body weight gain (BWG), specific growth rate (SGR), feed intake (FI) and protein efficiency ratio (PER) decreased with increasing dietary lipid levels. The sea cucumbers fed 1.9 g kg−1 crude lipid showed significantly higher (P < 0.05) BWG than those of the sea cucumbers fed 59.6 and 71.6 g kg−1 crude lipid. Intestinal protease and lipase activities generally increased with increasing dietary lipid levels. Eicosapentaenoic acid (EPA) content of body walls generally increased with increasing dietary lipid levels. Docosahexaenoic acid (DHA) content of body walls reached the maximum value at a dietary lipid level of 13.8 g kg−1. N-3 highly unsaturated fatty acid content followed the same pattern of DHA. According to the growth performance and body composition of sea cucumbers, it can be indicated that the optimum dietary lipid level for juvenile sea cucumbers is between 1.9 and 13.8 g kg−1.

Interactive effects of dietary lipid and phenotypic feed efficiency on the expression of nuclear and mitochondrial genes involved in the mitochondrial electron transport chain in rainbow trout.

A 2 × 3 factorial study was conducted to evaluate the effects of dietary lipid level on the expression of mitochondrial and nuclear genes involved in electron transport chain in all-female rainbow trout Oncorhynchus mykiss. Three practical diets with a fixed crude protein content of 40%, formulated to contain 10% (40/10), 20% (40/20) and 30% (40/30) dietary lipid, were fed to apparent satiety to triplicate groups of either low-feed efficient (F120; 217.66 ± 2.24 g initial average mass) or high-feed efficient (F136; 205.47 ± 1.27 g) full-sib families of fish, twice per day, for 90 days. At the end of the experiment, the results showed that there is an interactive effect of the dietary lipid levels and the phenotypic feed efficiency (growth rate and feed efficiency) on the expression of the mitochondrial genes nd1 (NADH dehydrogenase subunit 1), cytb (Cytochrome b), cox1 (Cytochrome c oxidase subunits 1), cox2 (Cytochrome c oxidase subunits 2) and atp6 (ATP synthase subunit 6) and nuclear genes ucp2α (uncoupling proteins 2 alpha), ucp2β (uncoupling proteins 2 beta), pparα (peroxisome proliferator-activated receptor alpha), pparβ (peroxisome proliferatoractivated receptor beta) and ppargc1α (proliferator-activated receptor gamma coactivator 1 alpha) in fish liver, intestine and muscle, except on ppargc1α in the muscle which was affected by the diet and the family separately. Also, the results revealed that the expression of mitochondrial genes is associated with that of nuclear genes involved in electron transport chain in fish liver, intestine and muscle. Furthermore, this work showed that the expression of mitochondrial genes parallels with the expression of genes encoding uncoupling proteins (UCP) in the liver and the intestine of rainbow trout. This study for the first time presents the molecular basis of the effects of dietary lipid level on mitochondrial and nuclear genes involved in mitochondrial electron transport chain in fish.

Effect of dietary lipid level on survival, growth performance and body composition of juvenile tench (Tinca tinca L.) fed practical diets

A 90-day experiment was conducted to evaluate the effects of practical diets with different lipid contents on survival, growth performance and whole-body composition of juvenile tench (Tinca tinca). Five-month-old juveniles (34.48 ± 0.77 mm total length, 0.382 ± 0.08 g weight) were fed practical diets with different lipid contents: 6.5%, 8.5%, 10%, 12%, 14%, 15.5% or 18%. Survival rates ranged from 96.7% to 100%. The highest growth was obtained with diets containing 8.5, 10 and 12% lipid. The five intermediate lipid contents (between 8.5% and 15.5%) caused lower FCRs (1.27–1.38). The percentages of fish with externally visible deformities were around 12%, with no significant differences due to the dietary lipid level. The relation among fatty acid profiles of the diets, body composition, growth performance of juveniles and requirements of other fish species is discussed.

Effects of dietary lipid level on growth, fatty acid composition, digestive enzymes and expression of some lipid metabolism related genes of orange-spotted grouper larvae (Epinephelus coioidesH.)

A 4-week study was conducted to investigate the effects of dietary lipid level on growth, fatty acid composition, activities of digestive enzymes and some lipid metabolism related genes of orange-spotted grouper larvae (Epinephelous coioides). Six isonitrogenous (57% crude protein) diets were formulated to contain graded contents of lipid (5.94%, 9.92%, 13.30%, 17.71% and 21.87% dry weight, respectively) using fish oil as main lipid source. Each diet was fed six times daily to triplicate groups of fish (71 ± 2 mg, 29 DAH). Results showed that the highest SGR and survival of larvae occurred in 17.71% and 13.30% lipid group respectively. The optimal dietary lipid requirement of larval grouper was estimated to be 15.99% based on SGR. Activities of pepsin and lipase were significantly higher in 17.71% lipid group compared to the rest ones. However, the highest activities of trypsin and amylase occurred in 9.92% and 5.94% lipid treatment respectively. The expression of fatty acid synthesis (FAS) decreased significantly with increasing dietary lipid, while the expression of lipoprotein lipase (LPL) and hormone sensitive lipase (HSL) significantly increased first and then decreased significantly. Compared to other treatment, larvae fed diets with 13.30% and 17.71% lipid have a significant higher relative expression of LPL and HSL respectively. Results of this study suggested that larvae fed the diet with appropriate lipid content showed higher growth performance. Moreover, dietary lipid content could also influence both de novo lipogenesis and lipolysis in transcriptional level.

The Effect of Dietary Lipid Levels on Growth Performance, Lipid Deposition, and Antioxidant Status of Juvenile Turbot, Scophthalmus maximus, Fed Isonitrogenous and Isoenergetics Diets

The purpose of this study was to investigate the effects of different lipid (fish oil/soybean oil=1:1, w/w) levels in diets with 45% crude protein on growth performance, body composition, and antioxidant status of turbot (Scophthalmus maximus L.). 2040 turbot (39±0.2g) were randomly divided into 4 groups with 3 replicates and fed isonitrogenous and isoenergetic diets with lipid levels of 6.0%(L6.0), 8.5%(L8.5), 11.0%(L11.0), and 13.5%(L13.5) for 56 days. Hepatic lipase (HL) and superoxide dismutase (SOD) activity were evaluated, as well as lipid peroxidation measured as malondialdehyde (MDA). Results showed that no significant difference was observed in feeding rate (FR), protein efficiency ratio (PER) and protein retention, while dietary lipid levels caused a significant increase (P&lt;0.05) in specific growth rate (SGR) The L13.5 group showed the highest lipid and energy retention and this was significantly higher than in other groups; lipid content in whole body and liver increased significantly with increased dietary lipid (P&lt;0.05); the HL and SOD activity, and MDA in the liver all increased significantly (P&lt;0.05)with dietary lipid supplementation in L13.5. In general, high dietary lipid levels enhanced growth rate of turbot, but the increment of growth was due mainly to excessive lipid deposition. Oxidation stress was observed in fish fed the diet containing 13.5% lipid. The optimal level of dietary lipid for good growth and antioxidant status in turbot was found to be 11%.

Effects of dietary lipid levels on growth, feed utilization, body composition and antioxidants of juvenile mud crab Scylla paramamosain (Estampador)

This study was carried out to determine the effects of dietary lipid levels on growth performance, feed utilization, body composition and antioxidant parameters of juvenile mud crab ( Scylla paramamosain ). Five isonitrogenic and isoenergetic experimental diets (45% crude protein) containing 0%, 3%, 6%, 9% and 12% added oils (named L0, L3, L6, L9 and L12, respectively) were fed to triplicate groups of 20 crabs (initial weight 11.53 ± 0.52 g, carapace width 3.92 ± 0.14 cm) for 8 weeks. The results showed that the survival, final body weight, carapace width, specific growth rate and molting frequency of crabs fed diet L6 were significantly higher than those of crabs fed diet L0, L3 or L12 ( P < 0.05). The highest feed conversion ratio and the lowest protein efficiency ratio were both observed in crabs fed diet L0 ( P < 0.05). The maximum voluntary feed intake was found in crabs fed diet L3 ( P < 0.05). The lipid contents of whole body and hepatopancreas increased remarkably with the elevated dietary lipid levels ( P < 0.05). The proportions of saturated fatty acid and monounsaturated fatty acid of the hepatopancreas were significantly higher in crabs fed diet L0 ( P < 0.05). The fatty acid composition of the hepatopancreas and muscle was consistent with those in the diets. In the hepatopancreas, crabs fed diet L12 accumulated the highest concentration of malondialdehyde than other groups ( P < 0.05), and the activities of antioxidant enzymes (superoxide dismutase, glutathione S-transferase and glutathione peroxidases) were all enhanced with the increased dietary lipid levels ( P < 0.05). The results suggested that a proper dietary lipid level of 8.52%–11.63% (optimum 9.5%) could maintain solid growth performance and antioxidant capacity of juvenile mud crab S. paramamosain . • We evaluate the effects of the diets with different lipid levels of juvenile mud crab. • The crabs cultured individually in a recirculation aquaculture system • The proper dietary lipid levels (8.52%–11.63%) could be suitable for juvenile mud crab. • The optimum dietary lipid requirement was approximate to 9.5%.

Effects of dietary lipid levels on growth performance, whole body composition and fatty acid composition of juvenile gibel carp (Carassius auratus gibelio)

We evaluated the effects of dietary lipid levels on the growth, whole body composition and fatty acid composition of juvenile gibel carp (Carassius auratus gibelio). Triplicate groups of 120 juvenile Carassius auratus gibelio (average weight: 2.05 g) were fed four isonitrogenic diets formulated with lipid levels of 1.4% (low), 6.1% (control), 11.6% (medium) and 21.1% (high) for 60 days. Weight gain in the 11.6% lipid group was significantly higher than that in the other groups (P 0.05) as dietary lipid levels increased. N-3 polyunsaturated fatty acids (PUFA) were not detected in faeces. The whole body lipid contents of 11.6% and 21.1% lipid level groups were significantly higher than that of the 1.4% and 6.1% lipid level groups (P < 0.05). The content of whole body n-3 PUFA in the 21.1% lipid level group enhanced significantly (P < 0.05). The whole body contents of eicosapntemacnioc acid (EPA) and docosahexaenoic acid (DHA) in the 21.1% lipid level group were the highest (P < 0.05). These results indicated that high dietary lipid levels (21.1%) inhibit weight gain and promoted fat and n-3 PUFA deposition in juvenile Carassius auratus gibelio, which led to liver damage. A dietary lipid level of 11.6% was determined to be optimal for growth performance of juvenile Carassius auratus gibelio.

Effect of dietary lipid level on growth, feed utilization and body composition of juvenile giant croaker Nibea japonica

Abstract Five isoproteic diets were designated to investigate the effects of dietary lipid levels (from 5% to 21%) on the growth performance, body composition and nutrition utilization of juvenile giant croaker, Nibea japonica (initially weighing, 6.67 ± 0.18 g per fish). Each diet was fed to triplicate tanks (15 fish per tank) for 8-weeks. Fish fed diets with low lipid levels (5–13%) showed significantly higher weight gain (WG) and special growth ratio (SGR) than those fed high lipid diets (17–21%) ( P Nibea japonica fed diets with lipid level from 5% to 21%. Diets with 9–13% lipid level could improve the protein utilization in this species. Fish fed diets with 5% and 9% lipid level had significantly lower viscerosomatic index (VSI), hepatosomatic index (HSI) and intraperitoneal fat ratio (IPF) than those fed with high lipid diets (13–21%) ( P P P P N. japonica .

Effect of dietary lipid level on growth performance, feed utilization and body composition by juvenile red spotted grouper (Epinephelus akaara)

This study was designed to determine the effect of dietary lipid level on growth performance, feed utilization and body composition of juvenile red spotted grouper, Epinephelus akaara. Triplicate groups of 12 fish (IBW = 2.51 g) with three isoenergetic and isonitrogenous experimental diets formulated by increasing lipid levels (5.98, 9.11 and 12.57 %) were fed to satiety for 8 weeks. At the end of the feeding trial, weight gain and specific growth rate were significantly higher for the fish fed diets with 9.11 and 12.57 % compared to the treatment which containing 5.98 % dietary lipid levels. With the increase of dietary lipid levels, feed conversion ratio decreased but protein efficiency ratio increased. As dietary lipid level increased, viscerosomatic index and intraperitoneal fat ratio increased dramatically, while no significant difference in hepatosomatic index was found in this experiment. In conclusion, under the experimental conditions, the increase of dietary lipid level beyond 9.11 % had no further beneficial effects.

Effects of dietary lipid levels on mitochondrial gene expression in low and high-feed efficient families of rainbow trout Oncorhynchus mykiss.

A 2 × 3 factorial study was conducted to evaluate the effects of dietary lipid level on mitochondrial gene expression in mixed sex rainbow trout Oncorhynchus mykiss. Practical diets with a fixed crude protein content of 42%, formulated to contain 10% (42/10), 20% (42/20) and 30% (42/30) dietary lipid, were fed to triplicate groups of either low-feed efficient (F129; mean ± s.d. = 105.67 ± 3.04 g initial average mass) or high-feed efficient (F134; mean ± s.d. = 97.86 ± 4.02 g) families of fish, to apparent satiety, twice per day, for 108 days. At the end of the experiment, diets 42/20 and 42/30 led to similar fish condition factors, which were higher than that observed with diet 42/10 (P < 0.05). F134 fish fed diet 42/10 showed the highest hepato-somatic index, while there was no significant difference among all the other treatments (P < 0.05). When the group of F134 fish fed diet 42/10 was used as the calibrator for gene expression analysis, the five genes selected for their involvement in lipid metabolism (complex I-nd1, complex III-cytb, complex IV-cox1, complex IV-cox2 and complex V-atp6) were up-regulated in the muscle and down-regulated in both the liver and the intestine. There was a significant family × diet interaction regarding nd1, cox2 and atp6 in the liver; nd1, cytb, cox1, cox2 and atp6 in the intestine, and nd1, cytb, cox1, cox2 and atp6 in the muscle (P < 0.05). The overall results of this study constitute basic information for the understanding of molecular mechanisms of lipid metabolism at the mitochondrial level in fishes.

Effect of protein and lipid levels in diets for female red claw crayfishCherax quadricarinatuson quality of offspring (juvenile), with emphasis on growth performance, biochemical composition and stress resistance to low oxygen, high ammonia and salinity

This study measures the effect of protein and lipid levels in broodstock diet on the quality of juvenile Cherax quadricarinatus. Diets with different contents of crude protein (180, 250, 310, 370 g kg−1) and lipids (30 and 70 g kg−1) were offered to female crayfish. Juveniles were used to assess initial weight (IW), biochemical composition (BC) and survival to stress tests (ST). After 50 days, growth was estimated. No significant effects of broodstock diet on IW and BC of juveniles were detected. Protein content (PC) significantly influenced growth (P < 0.05), with an optimum level of 250 g kg−1, representing a weight gain of 1.17 g (98.08% body weight). PC significantly influenced survival of juveniles exposed to ST (P < 0.05). Results from fitting dose–response models indicated that maximum survival was obtained with PC above 261, 258 and 312 g kg−1 for hypoxia, salinity, ammonia tests. No significant effect of dietary lipid level was observed on growth and survival to ST, except for greater survival to ammonia ST at lipid content of 70 g kg−1. We recommend feed with PC of 260 g kg−1 to simultaneously enhance growth and quality of juveniles.

Effects of Dietary Lipid Level on Growth and Feed Utilisation of Gilthead Seabream (Sparus Aurata L.) Reared at Mediterranean Summer Temperature

We investigated the effects of different dietary lipid levels on gilthead seabream, Sparus aurata, reared at Mediterranean summer temperature. Sixty fish (average weight 75 g) per tank were randomly distributed, in triplicate groups, in a recirculating rearing system (27±1°C) and fed ad libitum five isonitrogenous (46% dietary protein) diets with increasing lipid level (16, 18, 20, 22 and 24% named D16, D18, D20, D22 and D24, respectively), over 89 days. Specific growth rate and final body weight were not affected by dietary lipid levels. Feed conversion ratio was significantly higher (P≤0.05) in D16 as compared to the other treatments, most likely due to the shortage of dietary energy supply, coped with a significantly higher voluntary feed intake. Consequently, we obtained a significantly lower protein efficiency ratio and gross protein efficiency in D16. Gross lipid efficiency was significantly higher in D16 and D18 than in the other treatments. Biometric parameters and lipase activity in gut content were not influenced by dietary treatments. In conclusion, D18 seems the most suitable diet for gilthead seabream reared at Mediterranean summer temperature, providing both the lowest fish in fish out (FIFO) ratio and a protein sparing effect, which makes gilthead seabream’s production economically and environmentally more sustainable.

Effects of dietary lipid levels on fat deposition, lipid metabolize en-zyme and antioxidantic activities of &lt;I&gt;Chelon haematocheilus&lt;/I&gt;

Effects of dietary lipid levels on fat deposition, lipid metabolize en-zyme and antioxidantic activities of &lt;I&gt;Chelon haematocheilus&lt;/I&gt;

Effects of dietary lipid levels on serum biochemistry indices, immunity, and antioxidant activity in &lt;I&gt;Sebastiscus marmoratus&lt;/I&gt;

Effects of dietary lipid levels on serum biochemistry indices, immunity, and antioxidant activity in &lt;I&gt;Sebastiscus marmoratus&lt;/I&gt;

High dietary lipids elevate carbon loss without sparing protein in adequate protein-fed juvenile turbot (Psetta maxima)

This study was undertaken to determine the effects of dietary lipid levels on growth and nutrient utilization, and carbon (C), nitrogen (N) and phosphorus (P) balances in juvenile turbot (Psetta maxima) in brackish water. Four isonitrogenous diets (50 % protein) differing in dietary lipid levels from 10 to 19 by 3 % increments (named 10L, 13L, 16L and 19L, respectively) were fed to four replicate groups of fish with an initial weight of 54.4 ± 0.2 g for 9 weeks. Significantly better growth and feed conversion ratio were observed in fish fed 13L than those fed 16L and 19L. The whole body, fillet, viscera and liver dry matter and lipid levels were increased as dietary lipid was increased. Liver protein levels were lower in 16L and 19L than 10L. There was an ascending pattern in the whole-body C levels and C/N ratios with the increase in dietary lipids. No significant effect of dietary lipids on either protein efficiency ratio or N and P retentions was detected. Dietary lipids led to an increase in C losses to the environment. Overall, high dietary lipids when introduced at an adequate protein level did reduce growth and feed utilization without a protein-sparing effect and resulted in higher C losses in juvenile turbot reared, and a dietary lipid level of about 13 % seemed to be optimum.

Effects of dietary lipid levels on growth, feed utilization and mitochondrial function in low- and high-feed efficient families of rainbow trout (Oncorhynchus mykiss)

A 2×3 factorial study was conducted to investigate the effects of dietary lipid levels on growth, feed utilization and mitochondrial enzyme activities in juvenile all-female rainbow trout (Oncorhynchus mykiss). Practical diets with a fixed crude protein content of 42%, formulated to contain 10% (42/10), 20% (42/20) and 30% (42/30) dietary lipid, were fed to apparent satiety to triplicate groups of either low-feed efficient (low-FE, 105.67±3.04g initial average mass) or high-feed efficient (high-FE, 97.86±4.02g) families of fish, twice per day, for 108days. At the end of the experiment, the group of fish fed diets 42/20 and 42/30 showed higher growth and feed efficiency (FE), coupled with a lower daily feed consumption (FC), than fish fed 42/10 diet, although similar results were found with diets 42/10 and 42/30 for growth (P<0.05). With similar FC, the high-FE family showed higher growth, FE, protein efficiency ratio (PER) and protein productive value (PPV) than the low-FE family (P<0.05). Fish fed diets 42/20 and 42/30 had the highest PER and PPV (P<0.05). The lipid efficiency ratio was highest in fish from the high-FE family fed diet 42/10 (P<0.05). Fish fed diet 42/30 showed the highest visceral fat and viscerosomatic index (P<0.05). In the liver, the respiratory chain enzymatic activity was significantly affected by both diet and family for complexes I and IV, and by diet for complexes II, III and V (P<0.05). In the intestine, significant family×diet interaction effects were observed for complexes III and IV (P<0.05). There were both significant family and diet main effects on complexes I and II, whereas complex V was only affected by family (P<0.05). In the muscle, significant (P<0.05) diet×family interaction effects were observed for complexes II and IV activities; complex III activity was significantly affected by the diet, whereas complex V activity was affected by both the diet and the family main effects; the activity of complex I was not affected by the treatments (P>0.05). The overall results of this study established that feeding a 42% CP diet with a minimum of 20% dietary lipid leads to high growth, feed utilization on the one hand, and that these zootechnical parameters are coupled with high mitochondrial enzymatic function in the liver, the intestine and the muscle of rainbow trout. Also, as it was expected, the high-FE family showed higher response to treatments than the low-FE family.

Effects of dietary lipid levels on fat deposition and fatty acid profiles of GIFT, Oreochromis niloticus

The study mainly focused on the effects of dietary lipid levels on partial physique indices,the fat deposition and fatty acid profiles of muscle,liver and adipose tissue of peritoneal cavity in the juvenile fish of GIFT (Genetically Improved Farmed Tilapia,Oreochromis niloticus),and investigated its utilization capabilities of the fatty acid in diets.Triplicate groups of fish were fed for 90 days with the experimental diets formulated with increasing lipid levels (lipid levels group of 1.73%,3.71%,5.69%,7.67%,9.64% and 16.55%) using fish oil as the lipid source.Result showed condition factor of the fish in the 5.69%,7.67% and 9.64% groups at higher values contrasted to other groups.The hepatosomatic index of the 1.73% and 16.55% group were significantly higher than those other groups (P0.05).Fat content of muscle in 7.67% group were significantly higher than 3.71% group (P0.05) and significantly lower than 16.55% group of the fish (P0.05).It presented an uptrend on fat contents of muscle and liver and a little influence on fat contents of adipose tissue of peritoneal cavity when dietary lipid levels raising.The higher dietary lipid level,the more body fat deposition and the higher n-3 unsaturated fatty acids proportion of tissue total fatty acids.Results indicated that the partial fish physique indices were influenced by dietary lipid levels,especially hepatosomatic index.While the fish was fed an overabundance lipid diet,the fat was easy to be accumulated in the tissues of muscle and liver.The fat contents and fatty acid profiles of fish reflected the dietary lipid level and fatty acid profiles.

Molecular characterization of lipoprotein lipase from blunt snout bream Megalobrama amblycephala and the regulation of its activity and expression by dietary lipid levels

A full-length cDNA coding lipoprotein lipase (LPL) was cloned from the visceral adipose tissue of blunt snout bream Megalobrama amblycephala by RT-PCR and rapid amplification of cDNA ends (RACE) approaches. The cDNA obtained covered 2372bp with an open reading frame of 1524bp encoding 507 amino acids, including a putative signal peptide of 22 amino acids long. Sequence alignment and phylogenetic analysis revealed a high degree of conservation (63–97%) among most fish and higher vertebrates, retaining the consensus sequence, the polypeptide “lid”, the catalytic triad and eight cysteine residues at the N-terminal region. Then, a 10-week feeding trial was conducted to investigate the effects of dietary lipid levels (4%, 8% and 12%) on the activity and mRNA expression of LPL in M. amblycephala. LPL activities in the visceral adipose tissue and white skeletal muscle both increased significantly (P<0.05) with increasing dietary lipid levels, whereas no significant difference (P>0.05) was also observed in that of the liver. LPL expressions in the visceral adipose tissue, liver and white skeletal muscles all increased significantly (P<0.05) as dietary lipid levels increased. In addition, a graded tissue-specific expression pattern of LPL (visceral adipose tissue>liver>white skeletal muscle) was also observed. The results indicated that LPL gene of M. amblycephala showed a typical structure of the lipase family, and shared a high similarity with that of the other vertebrates. In addition, an up-regulation of both LPL expressions and activities was observed in various tissues by high dietary lipid levels.

Molecular characterization, tissue expression of acyl-CoA ∆9-desaturase-like gene, and effects of dietary lipid levels on its expression in the hepatopancreas of the Chinese mitten crab (Eriocheir sinensis)

Acyl-CoA Δ9-desaturase has important functions in fatty acid metabolism and cell membrane fluidity regulation. In this study, we isolated and characterized the acyl-CoA Δ9-desaturase-like cDNA encoded in Eriocheir sinensis (Chinese mitten crab) from the hepatopancreas by performing rapid-amplification of cDNA ends. To the best of our knowledge, this study is the first to perform this procedure in crustaceans. The full-length cDNA is 2419bp long and encodes a polypeptide with 347 amino acids that are highly homologous to related genes found in insects. Gene expression analysis (real-time quantitative PCR) revealed that acyl-CoA Δ9-desaturase-like transcripts were widely distributed in various tissues, in which a high expression level was observed in the hepatopancreas. A significantly increasing trend was also observed in the hepatopancreas at the megalopa stage to the maturity stage of the Chinese mitten crab. Acyl-CoA Δ9-desaturase gene expression is regulated by a number of developmental, dietary, hormonal, and environmental factors; thus, we determined the effects of acyl-CoA Δ9-desaturase-like mRNA expression in the hepatopancreas after the crabs were fed with different diets for 168days. The different diets were as follows: control diet without oil lipids (with 3% basic lipid of the fundamental diets); fish oil diet (FO; with added 3% of the fundamental diets); soybean oil diet (SO; with added 3% of the fundamental diets); and FO/SO diet (1:1; with added 3% of the fundamental diets). Results showed that the FO diet elicited a strong increasing effect on the amount of acyl-CoA Δ9-desaturase-like genes compared with control and SO diets.

Cloning and tissue distribution of a fatty acyl Δ6-desaturase-like gene and effects of dietary lipid levels on its expression in the hepatopancreas of Chinese mitten crab (Eriocheir sinensis)

Fatty acyl Δ6-desaturase is the rate-limiting enzyme in the biosynthetic pathway of highly unsaturated fatty acids (HUFAs) in vertebrates. In this report, a fatty acyl Δ6-desaturase-like cDNA was cloned from the hepatopancreas of Eriocheir sinensis (Chinese mitten crab) and characterized by performing rapid-amplification of cDNA ends. The 2278-bp long full-length cDNA encodes a polypeptide with 442 amino acids. Gene expression analysis via real-time quantitative polymerase chain reaction revealed that the fatty acyl Δ6-desaturase-like transcripts are widely distributed in various tissues, with high expression levels in the hepatopancreas and cranial ganglia. This study focuses on the nutritional regulation of genes involved in the HUFA biosynthetic pathway in Chinese mitten crab. A feeding trial was performed whereby crablets were fed for 238 d with four different diets: control diet without oil lipids (added with 3% basic lipid of the fundamental diets); fish oil diet (FO; added with 3% of the fundamental diets); soybean oil diet (SO; added with 3% of the fundamental diets); and FO/SO diet (1:1; added with 3% of the fundamental diets). The hepatopancreas of crabs sampled at 168 d and 238 d to determine the effects on fatty acyl Δ6-desaturase-like mRNA expression. The results show that the expression of fatty acyl Δ6-desaturase-like is higher in the hepatopancreas of crabs fed with SO diet than those fed with FO diet. Furthermore, gene expression increased by 2.45-fold in the hepatopancreas of crabs fed with SO after 238 d than those fed after 168 d but remained steady for those fed with FO after 238 d.