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Modern bed bugs are resistant to multiple insecticide classes, particularly the pyrethroids. The efficacy of pyrethroid-impregnated mattress liners marketed for bed bug management has been variable. This study evaluated the efficacy of a permethrin-impregnated mattress liner, ActiveGuard, against 24 bed bug strains, consisting of both Cimex hemipterus (F.) and Cimex lectularius L. A ‘mat assay’, employing an allethrin-impregnated mat, was used to establish the pyrethroid resistance profile of all strains. Three experiments were conducted to evaluate the effect of ActiveGuard exposure on bed bug knockdown: 1) exposing the bed bugs continuously on the liner for up to 24 d, 2) holding the bed bugs on the liner for either 4 or 6 h, and 3) placing a noninsecticide treated fabric above the liner with the bed bugs held continuously on top. Our results indicated that all modern strains (collected within the last 15 years during the current resurgence) were pyrethroid-resistant, although the magnitude of resistance was highly variable between strains. In the continuous exposure study, an incomplete knockdown was recorded for most modern bed bug strains, with some having no knockdown even up to 7 d of constant exposure. In the 4 or 6 h exposure study, the level of knockdown was reduced even further, and very few bed bugs were knocked down in the double fabric study. The results of this study indicate that pyrethroid-impregnated mattress liners are not likely to be effective in the management of most modern bed bug infestations involving either C. hemipterus or C. lectularius.

Fish are a major source of beneficial n-3 LC-PUFA in human diet, and there is considerable interest to elucidate the mechanism and regulatory aspects of LC-PUFA biosynthesis in farmed species. Long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis involves the activities of two groups of enzymes, the fatty acyl desaturase (Fads) and elongase of very long-chain fatty acid (Elovl). The promoters of elovl5 elongase, which catalyses the rate-limiting reaction of elongating polyunsaturated fatty acid (PUFA), have been previously described and characterized from several marine and diadromous teleost species. We report here the cloning and characterization of elovl5 promoter from two freshwater fish species, the carnivorous snakehead fish (Channa striata) and zebrafish. Results show the presence of sterol-responsive elements (SRE) in the core regulatory region of both promoters, suggesting the importance of sterol regulatory element-binding protein (Srebp) in the regulation of elovl5 for both species. Mutagenesis luciferase and electrophoretic mobility shift assays further validate the role of SRE for basal transcriptional activation. In addition, several Sp1-binding sites located in close proximity with SRE were present in the snakehead promoter, with one having a potential synergy with SRE in the regulation of elovl5 expression. The core zebrafish elovl5 promoter fragment also directed in vivo expression in the yolk syncytial layer of developing zebrafish embryos.

The capacity for long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis activity in a species depends on the enzymatic activities of fatty acyl desaturase (Fads) and elongation of very long-chain fatty acid (Elovl). The miniaturized fish Paedocypris micromegethes is a developmentally truncated cyprinid living in highly acidic water conditions in tropical peat swamps. The capacity for LC-PUFA biosynthesis in this species, which has a reduced genome size, is unknown. A high-quality de novo transcriptome assembly enabled the identification of a putative Fads2 and four Elovl. The Fads2 was verified as a P. micromegethes Fads2 ortholog with in vitro Δ5 and Δ6 activities. The Elovl sequences were established as an Elovl5, Elovl2, and two Elovl4 paralogs, namely Elovl4a and Elovl4b. These Elovl enzymes, mainly Elovl5 and Elovl2, fulfill the necessary C18, C20, and C22 PUFA elongation steps for LC-PUFA biosynthesis. Collectively, these results validate the presence of a complete repertoire of LC-PUFA biosynthesis enzymes in a tropical miniatured freshwater fish.

Multiple studies have linked lipid metabolism with intestinal bacterial structure in aquatic organisms. However, the possibility of the gut microbiota participating in synthesizing beneficial long-chain polyunsaturated fatty acid (LC-PUFA) remains vague. We profiled the gut microbiota of mud crab Scylla olivacea fed with either a LC-PUFA rich diet (FO), a LC-PUFA-poor but C18-PUFA substrate rich diet (LOCO), and diet with a similar profile as LOCO but with the inclusion of an antibiotic, oxolinic acid. Additionally, the microbiota of wild-caught S. olivacea was also analyzed. Compared to diet FO treatment, crabs fed diet LOCO contain a higher proportion of Proteobacteria, represented by Vibrio and Shewanella, two known taxonomy groups with PUFA biosynthesis capacity. Annotation of metagenomic datasets also suggests functional contribution by these two genera in terms of the KEGG pathway of unsaturated fatty acids biosynthesis and the keto-acyl synthase domains in the microbiota of LOCO treatment. Diet LOCOAB impeded the presence of Vibrio and Shewanella within the gut, and concurrently, the abundance of PUFA biosynthesis pathway-related genes. However, there was an increase in the function of short-chain fatty acids production within this diet, which was accompanied by a shift towards the abundance of phyla Bacteroidota and Spirochaetota, represented by Sunxiuqinia and Carboxylicivirga and Sediminispirochaeta, respectively. Collectively, these results exemplified bacterial communities and their corresponding PUFA biosynthesis pathways in the microbiota of a farmed crustacean species.

Astaxanthin (Axn) is an essential carotenoid for crustacean pigmentation, and docosahexaenoic acid (DHA) is an important fatty acid; both play key roles in maintaining the health of many aquaculture species. The present study explored the combined effect of dietary Axn and DHA on gonadal development and carotenoid deposition in adult females of the Chinese mitten crab, Eriocheir sinensis. A 2 × 3 factorial design of experimental diets was created to contain two levels of Axn (0 mg/kg and 100 mg/kg) and three levels of DHA oil (0%, 0.33%, and 0.67%). The results showed as follows: (1) For the culture performance, dietary DHA oil significantly increased the gonadosomatic index (GSI), and Diet 2 (Axn 0% + DHA oil 0.33%) had the highest GSI among all treatments. (2) For the enzymatic indicators in the hepatopancreas and hemolymph, supplementation with 0.33% DHA oil significantly improved the antioxidant capacity (T-AOC and MDA), immunity (AKP and ACP), and health status (e.g., GPT and GOT) of E. sinensis. (3) Supplementation with 100 mg/kg Axn significantly increased redness (a ∗ ) and Axn concentration in both the ovaries and hepatopancreas, and supplementation with 0.33% or 0.67% DHA oil produced a further significant improvement in Axn concentration when the diets were supplemented with 100 mg/kg of Axn. (4) As for proximate composition, dietary Axn and DHA significantly increased the deposition of total lipids and triacylglycerol in the hepatopancreas. As expected, the crabs fed diets with DHA supplementation showed an increase in the DHA percentage and DHA/EPA ratio in the ovaries and hepatopancreas. In conclusion, dietary Axn and DHA oil had positive effects on ovarian development in E. sinensis females. The optimal combination of dietary Axn and DHA oil was determined to be approximately 100 mg/kg and 0.33%, respectively, for this species during ovarian maturation.

Acute hepatopancreatic necrosis (AHPND) caused by pathogenic Vibrio parahaemolyticus strains (VpAHPND) and other Vibrio spp. resulted in significant economic losses (over USD 7 billion) in shrimp aquaculture. Several biocontrol strategies for VpAHPND have been proposed, including the use of probiotics, immunization and bioflocs. However, each of these alternatives has limitations, with varying success in removing VpAHPND from aquatic environments. The potential of Vibrio-predatory filamentous bacteria (VPFB) as a biocontrol agent on VpAHPND was investigated in this work. Three VPFBs from the genera Saprospira (CCB-QB6) and Aureispira (CCB-E and F) were isolated from seagrass habitat in Penang, Malaysia. The VPFBs inhibited the multiplication of VpAHPND as well as other Vibrio species such as V. owensii, V. harveyi, and V. alginolyticus. The VpAHPND and VPFB co-culture experiments showed that within 15 h of introducing strain E or F, the VpAHPND cell number was reduced to less than 1 × 104 cells/ml from an initial (1 × 107 cells/ml). Scanning electron microscopy revealed that VPFBs formed cell aggregates with VpAHPND within a few minutes by attachment on the cell surface of VPFBs cells before the Vibrio cells destroyed. These findings indicate that VPFBs have the potential to be used as a biocontrol agent for VpAHPND in shrimp aquaculture.

Elongation of very long-chain fatty acid (Elovl) proteins are key enzymes that catalyze the rate-limiting step in the fatty acid elongation pathway. The most recently discovered member of the Elovl family, Elovl8, has been proposed to be a fish-specific elongase with two gene paralogs described in teleosts. However, the biological functions of Elovl8 are still to be elucidated. In this study, we showed that in contrast to previous findings, elovl8 is not unique to teleosts, but displays a rather unique and ample phylogenetic distribution. For functional determination, we generated elovl8a (elovl8a−/−) and elovl8b (elovl8b−/−) zebrafish using CRISPR/Cas9 technology. Fatty acid composition in vivo and zebrafish liver cell experiments suggest that the substrate preference of Elovl8 overlapped with other existing Elovl enzymes. Zebrafish Elovl8a could elongate the polyunsaturated fatty acids (PUFAs) C18:2n-6 and C18:3n-3 to C20:2n-6 and C20:3n-3, respectively. Along with PUFA, zebrafish Elovl8b also showed the capacity to elongate C18:0 and C20:1. Gene expression quantification suggests that Elovl8a and Elovl8b may play a potentially important role in fatty acid biosynthesis. Overall, our results provide novel insights into the function of Elovl8a and Elovl8b, representing additional fatty acid elongases not previously described in chordates.

The silver barb (Barbonymus gonionotus), a widely distributed cyprinid in Southeast Asia, has a reasonable deposition of the physiologically important omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), implying the existence of a functional LC-PUFA biosynthesis pathway. In relation to this, the cloning and functional characterisation of a fatty acyl desaturase (Fads) and fatty acyl elongase (Elovl) were examined to elucidate the capacity of silver barb in converting α-linolenic acid (ALA; 18:3n-3) into eicosapentaenoic acid (EPA; 20:5n-3) and subsequently docosahexaenoic acid (DHA; 22:6n-3), and linoleic acid (LA; 18:2n-6) into arachidonic acid (ARA; 20:4n-6). Sequence analysis showed that the cloned cDNAs correspond to fads2 and elovl5. In terms of function, the Fads2 showed Δ6, Δ5 and Δ8 desaturation activities, while the Elovl5 showed activities towards polyunsaturated fatty acid (PUFA) substrates at preference of C18 > C20 > C22. Both enzymes showed higher activities towards n-3 PUFAs as compared to n-6 PUFAs. Taken together, these results showed the presence of all the required enzymes for biosynthesis of EPA and ARA from ALA and LA, respectively in silver barb fish. Both genes are highly expressed in brain and liver. Juvenile fish fed with ALA-rich diet showed higher expression of hepatic fads2 and elovl5 than to those fed with LC-PUFA-rich diet. Dietary ALA also contributed to the biosynthesis and deposition of EPA and DHA in fish tissues, albeit lower than levels achieved with the fish oil (FO)-based diet. Overall, this study shows the presence of functional Fads2 and Elovl5 in a farmed cyprinid species, which contributes to LC-PUFA biosynthesis during limited dietary LC-PUFA intake.

Momordica charantia is a popular vegetable associated with effective complementary and alternative diabetes management in some parts of the world. However, the molecular mechanism is less commonly investigated. In this study, we investigated the association between a major cucurbitane triterpenoid isolated from M. charantia, 3β,7β,25-trihydroxycucurbita-5,23(E)-dien-19-al (THCB) and peroxisome proliferator activated receptor gamma (PPARγ) activation and its related activities using cell culture and molecular biology techniques. In this study, we report on both M. charantia fruit crude extract and THCB in driving the luciferase activity of Peroxisome Proliferator Response Element, associated with PPARγ activation. Other than that, THCB also induced adipocyte differentiation at far less intensity as compared to the full agonist rosiglitazone. In conjunction, THCB treatment on adipocytes also resulted in upregulation of PPAR gamma target genes expression, AP2, adiponectin, LPL and CD34 at a lower magnitude compared to rosiglitazone’s induction. THCB also induced glucose uptake into muscle cells and the mechanism is via Glut4 translocation to the cell membrane. In conclusion, THCB acts as one of the many components in M. charantia to induce hypoglycaemic effect by acting as PPARγ ligand and inducing glucose uptake activity in the muscles by means of Glut4 translocation.

© 2021 by the authors., Elongation of very long-chain fatty acid (Elovl) proteins are key enzymes that catalyze the rate-limiting step in the fatty acid elongation pathway. The most recently discovered member of the Elovl family, Elovl8, has been proposed to be a fish-specific elongase with two gene paralogs described in teleosts. However, the biological functions of Elovl8 are still to be elucidated. In this study, we showed that in contrast to previous findings, elovl8 is not unique to teleosts, but displays a rather unique and ample phylogenetic distribution. For functional determination, we generated elovl8a (elovl8a−/−) and elovl8b (elovl8b−/−) zebrafish using CRISPR/Cas9 technology. Fatty acid composition in vivo and zebrafish liver cell experiments suggest that the substrate preference of Elovl8 overlapped with other existing Elovl enzymes. Zebrafish Elovl8a could elongate the polyunsaturated fatty acids (PUFAs) C18:2n-6 and C18:3n-3 to C20:2n-6 and C20:3n-3, respectively. Along with PUFA, zebrafish Elovl8b also showed the capacity to elongate C18:0 and C20:1. Gene expression quantification suggests that Elovl8a and Elovl8b may play a potentially important role in fatty acid biosynthesis. Overall, our results provide novel insights into the function of Elovl8a and Elovl8b, representing additional fatty acid elongases not previously described in chordates., This study was supported by the National Natural Science Foundation of China (31872579) and Universiti Sains Malaysia (311.PCCB.411954. USM-Strategic Initiative-Ten Q1Q2).

While the capacity for long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis has been elucidated in vertebrates and several invertebrate phyla, the comparative knowledge in crustaceans remains vague. A key obstacle in mapping the full spectrum of LC-PUFA biosynthesis in crustacean is the limited evidence of the functional activities of enzymes involved in desaturation or elongation of polyunsaturated fatty acid substrates. In this present study, we report on the cloning and functional characterization of two Elovl elongases from the orange mud crab

The Malaysian mahseer (Tor tambroides) is an iconic and highly-priced freshwater large cyprinid with a natural dietary preference towards riverine fruits. Previous works indicate that dietary C18 polyunsaturated fatty acids can fulfill mahseer's essential fatty acid requirements. Given the need to reduce the use of fish meal and fish oil in aquafeed, there is considerable interest to sustain healthy levels of the beneficial n-3 long-chain polyunsaturated fatty acids (LC-PUFA) in farmed fish. A prerequisite for a functional LC-PUFA biosynthesis pathway is an entire repertoire of desaturase (Fads) and elongase (Elovl) enzymes required for specific steps along the path. We showed here the presence of a Fads2 and two elongases, Elovl5 and Elovl2, in mahseer. These enzymes function collectively to convert C18 PUFA to the C20 LC-PUFA through Δ6 and Δ5 desaturation processes working in tandem with the Elovl5 elongation activities. Subsequently, further conversion to docosahexaenoic acid (DHA; 22:6n-3) involves Δ6 desaturation and Elovl2 and Elovl5. These enzymes displayed a typical expression pattern of freshwater teleost at the mRNA level, with significant transcripts in liver, intestine, and brain tissues. Under limited dietary LC-PUFA intakes, the expression of these genes in the liver was elevated. Tissue fatty acid composition also suggests the conversion of dietary α-linolenic acid (ALA; 18:3n-3) and linoleic acid (LA; 18:2n-6) to their respective LC-PUFA for deposition in brain and muscle tissues. Although the highest concentration of n-3 LC-PUFA is obtained using fish oil-based diet, our results showed considerable accumulation of EPA and DHA with dietary ALA provision. Taken together, we show the existence of complete machinery for the biosynthesis of LC-PUFA from C18 PUFA in mahseer and validates the mahseer's capacity to utilize dietary vegetable oils (VO) both growth and n-3 LC-PUFA deposition.

Brachyuran aquaculture is gaining attention due to its high market value across the globe. In efforts to maximize the benefits of monosex culture in brachyurans, sex manipulation techniques benefit from the knowledge of sex determination system. However, unlike fish, information on the sex determination of decapod crustaceans including brachyurans remains disorganized. The compilation of literature shows most studies focused primarily on economically important brachyuran species and that the male heterogamety (XX/XY) or female heterogamety (ZW/ZZ) genetic sex determination system dominates among brachyuran species. Although the master regulatory gene in brachyuran species remains unknown, an increasing number of sex determination-related candidate genes are emerging. The current knowledge on the sex determination system of brachyurans could pave the way for the future establishment of breeding programs and the development of monosex culture systems in high-value brachyuran species.

The spiny lobster Sagmariasus verreauxi is an emerging lobster species for intensive aquaculture. The lack of any nutritional information required for feed development in this species initiated this study to understand the effect of different dietary lipid sources on tissue lipid profiles and expression of selected lipid metabolising genes. Krill oil, marine oil (blend of fish oils), and vegetable oil (combination of linseed and palm oil), were utilised to formulate three experimental feeds with different phospholipid, triacylglycerol and polyunsaturated fatty acid profiles. Experimental feeds were administered to freshly moulted juvenile S. verreauxi for 50 to 55 days, to determine the effect of lipid sources on the nutritional status, fatty acid composition and expression of genes related to fatty acid biosynthesis, β-oxidation, lipid catabolism and regulation of lipid metabolism. While there were no significant differences in terms of weight gain and mortality among different dietary treatments, the fatty acids composition in the hepatopancreas and to some extent, muscle tissues correlated with the fatty acids composition of the respective dietary treatments. Vegetable oil diet resulted in higher expression of genes related to β-oxidation, which indicates selectivity towards utilisation of monounsaturated fatty acids for energy in this species. In tandem, genes related to fatty acid and cholesterol biosynthesis were upregulated, suggesting their importance in the marine lobster diet. This is the first report on the use of formulated feeds to successfully maintain juvenile S. verreauxi.

We determined the complete mitogenomes of two fiddler crabs Uca rosea (15,643 bp) and Uca paradussumieri (15,614 bp) of Ocypodidae within Brachyura. Both consist of 37 genes (13 protein-coding gene...

The biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFA), a process to convert C18 polyunsaturated fatty acids into eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) or arachidonic acid (ARA), requires the concerted activities of two enzymes, the fatty acyl desaturase (Fads) and elongase (Elovl). This study highlights the cloning, functional characterisation and tissue expression pattern of a Fads and an Elovl from the Boddart's goggle-eyed goby (Boleophthalmus boddarti), a mudskipper species widely distributed in the Indo-Pacific region. Phylogenetic analysis revealed that the cloned fads and elovl are clustered with other teleost orthologs, respectively. The investigation of the genome of several mudskipper species, namely Boleophthalmus pectinirostris, Periophthalmus schlosseri and Periophthalmus magnuspinnatus, revealed a single Fads2 and two elongases, Elovl5 and Elovl4 for each respective species. A heterologous yeast assay indicated that the B. boddarti Fads2 possessed low desaturation activity on C18 PUFA and no desaturation on C20 and C22 PUFA substrates. In comparison, the Elovl5 showed a wide range of substrate specificity, with a capacity to elongate C18, C20 and C22 PUFA substrates. An amino acid residue that affects the capacity to elongate C22:5n-3 was identified in the B. boddarti Elovl5. Both genes are highly expressed in brain tissue. Among all tissues, DHA is highly concentrated in neuron-rich tissues, whereas EPA is highly deposited in gills. Taken together, the results showed that due to the inability to perform desaturation steps, B. boddarti is unable to biosynthesise LC-PUFA, relying on dietary intake to acquire these nutrients.

Long-chain polyunsaturated fatty acid biosynthesis, a process to convert C18 polyunsaturated fatty acids to eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) or arachidonic acid (ARA) requires the concerted activities of two enzymes, the fatty acyl desaturase (Fads) and elongase (Elovl). This study highlights the cloning, functional characterisation and tissue expression pattern of a Fads and Elovl from the Boddart’s goggle-eyed goby (Boleophthalmus boddarti), a mudskipper species widely distributed in the Indo-Pacific region. Phylogenetic analysis revealed that the cloned Fads and Elovl are clustered with other teleost Fads2 and Elovl5 orthologs, respectively. Interrogation of the genome of several mudskipper species, namelyB. pectinirostris, Periophthalmus schlosseriandP. magnuspinnatusrevealed a single Fads2 for each respective species while two elongases, Elovl5 and Elovl4 were detected. Using a heterologous yeast assay, theB. boddartiFads2 was shown to possess low desaturation activity on C18 PUFA. In addition, there was no desaturation of C20 and C22 substrates. In comparison, the Elovl5 showed a wide range of substrate specificity, with capacity to elongate C18, C20 and C22 PUFA substrates. We identified an amino acid residue in theB. boddartiElovl5 that affect the capacity to bind C22 PUFA substrate. Both genes are highly expressed in brain tissue. Among all tissues, DHA is highly concentrated in neuron-rich tissues while EPA is highly deposited in gills. Taken together, the results showed that due to disability of desaturation steps,B. boddartiis unable to biosynthesis LC-PUFA, relying on dietary intake to acquire these nutrients.

Long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis involves the activities of two groups of enzymes, the fatty acyl desaturases (Fads) and elongases of very long-chain fatty acid (Elovl). Fish are major source of beneficial n-3 LC-PUFA in human diet and there is a considerable interest to elucidate the mechanism and regulatory aspects of LC-PUFA biosynthesis in farmed fish species. The promoter of elovl5 elongase, which catalyze the rate limiting reaction of adding two carbons to the C18 PUFA have been previously described and characterized from several marine and diadromous teleost species. We report here the cloning and characterization of the elovl5 promoter from two freshwater fish species, the carnivorous snakehead fish (Channa striata) and zebrafish. Results show the importance of sterol regulatory element binding protein (Srebp) and the corresponding sterol responsive element (SRE) in the core regulatory region of both promoters. Mutagenesis luciferase and electrophoretic mobility shift assays confirm that SRE is indispensable for basal transcriptional activation in both species. In addition, several Sp1 binding sites located in close proximity with SRE were present in the snakehead promoter, with one having a potential synergy with SRE in regulating elovl5 expression. The core elovl5 promoter fragments of both species also directed in vivo expression in the yolk syncytial layer of developing zebrafish embryos. This study is the first functional promoter analysis of Elovl5 in freshwater teleost.

There is a lack of understanding on how the environment and trophic niche affect the capability of long-chain polyunsaturated fatty acids (LC-PUFA) in freshwater carnivorous teleost. In this present study, we isolated and functionally characterised a fatty acyl desaturase (Fads) from the striped snakehead Channa striata. Sequence comparison and phylogenetic analysis suggested a Fads2 protein that is closely related to previously characterised Fads2 proteins from freshwater carnivorous and marine herbivorous fish species. We further demonstrated the capacity of Δ6 and Δ5 desaturation activities for this particular desaturase, with highest activities towards the conversion of omega-3 (n-3) polyunsaturated fatty acids (PUFA). Low Δ4 desaturation activity was also detected, although the significance of this at a physiological level remains to be studied. The expression of this striped snakehead Δ6/Δ5 fads2 gene was highest in brain, followed by liver and intestine. In liver, diet fortified with high LC-PUFA concentration impeded the expression of Δ6/Δ5 fads2 gene compared to vegetable oil (VO) based diets. The discovery of Δ6/Δ5 Fads2 desaturase here complements the previous discovery of a Δ4 Fads2 desaturase and an Elovl5 elongase, lending proof to the existence of all the required enzymatic machinery to biosynthesise LC-PUFA from C18 PUFA in a freshwater carnivorous species.

Despite the potential of vegetable oils as aquafeed ingredients, a major drawback associated with their utilization is the inferior level of beneficial n-3 long-chain polyunsaturated fatty acids (LC-PUFA). Echium oil (EO), which is rich in stearidonic acid (SDA, 18:4n-3), could potentially improve the deposition of n-3 LC-PUFA as the biosynthesis of LC-PUFA is enhanced through bypassing the rate-limiting ∆6 desaturation step. We report for the first time an attempt to investigate whether the presence of a desaturase (Fads2) capable of ∆4 desaturation activities and an elongase (Elovl5) will leverage the provision of dietary SDA to produce a higher rate of LC-PUFA bioconversion. Experimental diets were designed containing fish oil (FO), EO or linseed oil (LO) (100FO, 100EO, 100LO), and diets which comprised equal mixtures of the designated oils (50EOFO and 50EOLO) were evaluated in a 12-week feeding trial involving striped snakeheads (Channa striata). There was no significant difference in growth and feed conversion efficiency. The hepatic fatty acid composition and higher expression of fads2 and elovl5 genes in fish fed EO-based diets indicate the utilization of dietary SDA for LC-PUFA biosynthesis. Collectively, this resulted in a higher deposition of muscle eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) compared to LO-based diets. Dietary EO improved the ratio of n-3 LC-PUFA to n-6 LC-PUFA in fish muscle, which is desirable for human populations with excessive consumption of n-6 PUFA. This study validates the contribution of SDA in improving the content of n-3 LC-PUFA and the ratio of EPA to arachidonic acid (ARA, 20:4n-6) in a freshwater carnivorous species.

To date, the genus Mangrovimonas consists of only one species, Mangrovimonas yunxiaonensis strain LY01 that is known to have algicidal effects against harmful algal blooms (HABs) of Alexandrium tamarense. In this study, the whole genome sequence of three Mangrovimonas-like strains, TPBH4(T)(=LMG 28913(T),=JCM 30882(T)), ST2L12(T)(=LMG 28914(T),=JCM 30880(T)) and ST2L15(T)(=LMG 28915(T),=JCM 30881(T)) isolated from estuarine mangrove sediments in Perak, Malaysia were described. The sequenced genomes had a range of assembly size ranging from 3.56 Mb to 4.15 Mb which are significantly larger than that of M. yunxiaonensis LY01 (2.67 Mb). Xylan, xylose, L-arabinan and L-arabinose utilization genes were found in the genome sequences of the three Mangrovimonas-like strains described in this study. In contrast, these carbohydrate metabolism genes were not found in the genome sequence of LY01. In addition, TPBH4(T) and ST2L12(T) show capability to degrade xylan using qualitative plate assay method.

Numerous documented ethnopharmacological properties have been associated with Swietenia macrophylla (Meliaceae), with its seed extract reported to display anti-hypoglycemic activities in diabetic rats. In the present study, three compounds isolated from the seeds of S. macrophylla were tested on a modified ELISA binding assay and showed to possess PPARγ ligand activity. They were corresponded to PPARγ-mediated cellular response, stimulated adipocyte differentiation but produced lower amount of fat droplets compared to a conventional anti-diabetic agent, rosiglitazone. The up-regulation of adipocytes was followed by increased adipocyte-related gene expressions such as adiponectin, adipsin, and PPARγ. The S. macrophylla compounds also promoted cellular glucose uptake via the translocation of GLUT4 glucose transporter.

The capacity of crustaceans to biosynthesise long-chain polyunsaturated fatty acids has yet to be fully defined, due to the lack of evidence on the functional activities of enzymes involved in desaturation or elongation of fatty acid substrates. We report here the cloning and in vitro functional analysis of an elongase from the orange mud crab, Scylla olivacea. Sequence and phylogenetic analysis placed the elovl close to the vertebrate Elovl1 and Elovl7 clade, which is distinct from the other remaining five Elovl families. The elongase was also clustered together with several elongases from crustaceans and insects. This elongase showed activities towards 16:1n-7, and at lower rate, linoleic acid (18:2n-6) and linolenic acid (18:3n-3). To our knowledge this is the first description of a functional enzyme involved in biosynthesis of long-chained polyunsaturated fatty acids in a crustacean species. Expression of the S. olivacea elovl7-like mRNA was prominent in stomach, intestine and gill tissues, due to the need to regulate the permeability of epithelial tissue through modification of fatty acid compositions. The implication of our findings, in terms of ability of Crustacea phylum to biosynthesise polyunsaturated fatty acids is discussed.

Although freshwater biomes cover less than 1% of the Earth's surface, they have disproportionate ecological significances. Attempts to study the taxonomy and function of freshwater microbiota are currently limited to samples collected from temperate lakes. In this study, we investigated samples from the photic and aphotic of an aquaculture site (disturbed) of Temengor Lake, a tropical lake in comparison with the undisturbed site of the lake using 16S rRNA amplicon and shotgun metagenomic approaches. Vertical changes in bacterial community composition and function of the Temengor Lake metagenomes were observed. The photic water layer of Temengor Lake was dominated by typical freshwater assemblages consisting of Proteobacteria, Actinobacteria, Bacteroidetes, Verrucomicrobia, and Cyanobacteria lineages. On the other hand, the aphotic water featured in addition to Proteobacteria, Bacteroidetes, Verrucomicrobia, and two more abundant bacterial phyla that are typically ubiquitous in anoxic habitats (Chloroflexi and Firmicutes). The aphotic zone of Temengor Lake exhibited genetic potential for nitrogen and sulfur metabolisms for which terminal electron acceptors other than oxygen are used in the reactions. The aphotic water of the disturbed site also showed an overrepresentation of genes associated with the metabolism of carbohydrates, likely driven by the enrichment of nutrient resulting from aquaculture activities at the site. The results presented in this study can serve as a basis for understanding the structure and functional capacity of the microbial communities in the photic and aphotic zones/water layers of tropical man-made lakes.

The front-end desaturases (Fads) are rate-limiting enzymes responsible for production of long-chain polyunsaturated fatty acids (LC-PUFA). The full spectrum of the transcriptional regulation of fads is still incomplete, as cloning of fads promoter is limited to a few species. Here, we described the cloning and characterisation of the zebrafish fads2 promoter. Using 5′-deletion and mutation analysis on this promoter, we identified a specific region containing the sterol regulatory element (SRE) which is responsible for the activation of the fads2 promoter. In tandem, two conserved CCAAT boxes were also present adjacent to the SRE and mutation of either of these binding sites attenuates the transcriptional activation of the fads2 promoter. An in vivo analysis employing GFP reporter gene in transiently transfected zebrafish embryos showed that this 1754 bp upstream region of the fads2 gene specifically directs GFP expression in the yolk syncytial layer (YSL) region. This indicates a role for LC-PUFA in the transport of yolk lipids through this tissue layer. In conclusion, besides identifying novel core elements for transcriptional activation in zebrafish fads2 promoter, we also reveal a potential role for fads2 or LC-PUFA in YSL during development.