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Glucose transporter 4 (GLUT4) is comprehensively investigated in mammals, while the comparative research of GLUT4 in common carp is deficient. To investigate the function of GLUT4, carp glut4 was first isolated. The open reading frame of carp glut4 was 1518 bp in length, encoding 505 amino acids. A high-sequence homology was identified in carp and teleost, and the phylogenetic tree displayed that the carp GLUT4 was clustered with the teleost. A high level of glut4 mRNA was analysed in fat, red muscle and white muscle. After fasting treatment, glut4 mRNA expression was increased significantly in muscle. In the oral glucose tolerance test experiment, glut4 mRNA was also significantly elevated in muscle, gut and fat. Furthermore, intraperitoneal injection of insulin resulted in the upregulation of glut4 gene expression significantly in white muscle, gut and fat. On the contrary, the glut4 mRNA level in the white muscle, gut and fat was markedly downregulated after glucagon injection. These results suggest that GLUT4 might play important roles in food intake and could be regulated by nutrient condition, insulin and glucagon in common carp. Our study is the first to report on GLUT4 in common carp. These data provide a basis for further study on fish GLUT4.

Lipid metabolism disorders are found ubiquitously in farmed fish and occur as a result of excessive fat accumulation. Previous studies have found that miR-33 is involved in lipid metabolism; however, its role in fish lipid metabolism is unclear. We sought to clarify this relationship in grass carp in vivo and in vitro. Our findings revealed the length of miR-33 to be 65 bp. Phylogenetic tree analysis showed that grass carp miR-33 was most closely related to fish miR-33 (Siganus canaliculatus). Hepatocytes transfected with miR-33 mimic displayed markedly raised TG content (P

Strain CFH S0501T, a novel Gram-stain-positive, aerobic, rod-shaped, endospore-forming and motile micro-organism with peritrichous flagella, was isolated from a sediment sample collected from the Yellow River in Henan Province, PR China. Optimum growth was observed at 28 °C, pH 7.0 and without NaCl. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that the strain belonged to the genus Brevibacillus and was closely related to Brevibacillus centrosporus DSM 8445T and Brevibacillus ginsengisoli Gsoil 3088T (with 96.8 and 96.7 % sequence similarity, respectively). The predominant menaquinone was MK-7. Major cellular fatty acids were anteiso-C15 : 0 and iso-C15 : 0. Polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, two unidentified phospholipids and an unidentified polar lipid. The cell-wall peptidoglycan was found to contain meso-diaminopimelic acid. The genome size was 5.26 Mbp with a G+C content of 49.7 mol%. The average nucleotide identity (ANI) and in silico DNA–DNAhybridization (DDH) values between CFH S0501T and the other species of the genus Brevibacillus were found to be low (ANIm T is considered to represent a novel species, for which the name Brevibacillus migulae sp. nov. is proposed. The type strain is CFH S0501T (=DSM 29940T=BCRC 80809T).

A novel Gram-stain-positive bacterium, designated CFH 91151T, was isolated from sediment collected from a saline lake in Yuncheng, Shanxi Province, PR China. Cells of strain CFH 91151T were rod-or v-shaped, aerobic, non-motile, non-spore-forming and halotolerant. Results of 16S rRNA gene sequence analysis revealed that strain CFH 91151T was closely related to Isoptericola variabilis MX5T and Isoptericola nanjingensis H17T (98.7 and 98.4% sequence similarity, respectively). The strain grew at 4–45 °C, pH 5.0–9.0 and with 0–14.0 % (w/v) NaCl. Cells were positive for catalase, nitrate was not used and H2S was not produced. Major cellular fatty acids were anteiso-C15 : 0 (62.76 %), anteiso-C17 : 0 (12.09 %) and iso-C15 : 0 (9.46 %). The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, two unidentified phospholipids and three unidentified glycolipids. The menaquinone was MK-9 (H4). The genome size was 4.10 Mbp with a G+C content of 72.4 mol%. The average amino acid identity (ANI) and in silico DNA–DNA hybridization (DDH) values between CFH 91151T and the other species of the genus Isoptericola were found to be low (ANIm T is considered to represent a novel species, for which the name Isoptericola halalbus sp. nov. is proposed. The type strain is CFH 91151T (=DSM 105976T=KCTC 49061T).

A bacteria strain, designated CFH 90008T, was isolated from a salt lake sediment sample collected from Yuncheng city, Shanxi Province, PR China. Strain CFH 90008T was Gram-stain-negative, strictly aerobic, motile with lateral flagella and rod-shaped. Colonies were yellow, circular and smooth. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain CFH 90008T belonged to the genus Halomonas , showing highest sequence similarity to Halomonas daqingensis DQD2-30T (98.6 %), Halomonas saliphila LCB169T (98.5 %), Halomonas desiderata FB2T (98.1 %) and Halomonas kenyensis AIR-2T (98.0 %). Good growth was observed at 10–50 °C, pH 6.0–9.0 and with NaCl concentration from 1.0 to 12.0 % (w/v). The predominant quinone was Q9. The major fatty acid (>10 %) was C18 : 1 ω7c, C16 : 0 and C16 : 1 ω7c. The genome of strain CFH 90008T was 4.36 Mbp with a genomic DNA G+C content of 66.7 mol%. Based on low average nucleotide identity and DNA–DNAhybridization results, chemotaxonomic characteristics, and differential physiological properties, strain CFH 90008T could not be classified into any recognized species of the genus Halomonas . Therefore, a new species, for which the name Halomonas lactosivorans sp. nov. is proposed. The type strain is CFH 90008T (=DSM 103220T=KCTC 52281T).

A novel actinobacterium, designated strain CFH S0261T, was isolated from a sediment sample of the Yellow River. The taxonomic position of the strain was investigated by using a polyphasic approach. Cells of strain CFH S0261T were Gram-reaction-positive, aerobic, non-motile. Growth occurs at 15–37 °C, pH 6.0–8.0 and with 0–9.0 % (w/v) NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain CFH S0261T was a member of the genus Amycolatopsis . The 16S rRNA gene sequence similarity indicated that strain CFH S0261T is most closely related to the type strains of Amycolatopsis niigatensis LC11T (98.95 %), Amycolatopsis echigonensis LC2T (98.81 %) and Amycolatopsis albidoflavus IMSNU 22139T (98.73 %). The whole-genome of CFH S0261T showed a G+C content of 69.5 mol%. The ANI values and in silico DDH values between CFH S0261T and the other species of the genus Amycolatopsis were found to be low (ANIb T was meso-diaminopimelic acid and the whole-cell hydrolysate comprised arabinose, galactose, glucose, rhamnose and ribose. The predominant menaquinone was MK-9(H4). The major cellular fatty acids were C16 : 0, iso-C15 : 0 and iso-C16 : 0. The polar lipid profile contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides and four unidentified glycolipids. On the basis of phenotypic, genotypic and phylogenetic data, strain CFH S0261T represents a novel species of the genus Amycolatopsis , for which the name Amycolatopsis nivea sp. nov. is proposed. The type strain is CFH S0261T (=KCTC 39515T =CCTCC AA 2014028T).

The GH (growth hormone)/IGFs (insulin-like growth factors) system has an important function in the regulation of growth. In this system, IGFBPs play a crucial regulatory role in IGF functions. As a member of the IGFBP family, IGFBP2 can bind to IGF and regulate IGF functions to regulate development and growth. In addition, IGFBP2 shows key regulatory functions in cell proliferation and metabolism. In this study, the igfbp2 gene was cloned from grass carp (Ctenopharyngodon idellus) liver. The ORF of grass carp igfbp2 is 834 bp long and encodes 277 amino acids. The tissue distribution results showed that igfbp2 is expressed in multiple tissues in grass carp and has a high expression level in the liver. In the OGTT, igfbp2 expression was significantly decreased in the liver and brain after 6 h of treatment with glucose. In vitro, igfbp2 expression in grass carp's primary hepatocytes was significantly suppressed by insulin after treatment for 6 and 12 h. Moreover, igfbp2 expression was markedly increased in a dose-dependent manner with glucagon incubation in grass carp's primary hepatocytes. To the best of our knowledge, this is the first report about Igfbp2 in grass carp. These results will provide a basis for the in-depth study of grass carp Igfbp2.

The South-to-North Canal System (SNCS) is the largest water diversion project in the world, and it transports water from water-sufficient southern and central to water-deficient northeastern China. The oriental river prawn is the most adaptable prawn species in this ecosystem and a dominant member of the benthic community. In this study, in order to obtain more information regarding the ecological functions of the prawn in the benthic food webs of the SNCS ecosystem, the trophic ecology of the prawn from the canal and the upstream reservoir was compared in the two ecosymtems. The prawn stable isotopic compositions of different prawn sizes (large, medium and small), niche spaces and the trophic positions were compared between the two ecosymtems. Results showed that in the main canal, particulate organic matter (POM) composed more than 40% of the food consumed by all three size prawns. Compared to small prawn, the diet of medium and large prawns were proportionally higher in POM and zooplankton. In the upstream reservoir, large prawn fed primarily on benthic microalgae, which composed 72.8% of the prawn diet. The pelagic food webs provided 93.5% food source for the canal prawn, while the benthic food webs afforded 72.4% food source for the reservoir prawn. Thereafter, the ecological functions of the prawn in the two ecosystems were also different due to their varied food diet. Careful considerations were suggested when using biomanipulation in the SNCS ecosystem.

A novel thermophilic bacterium, designated CFH 72773T was isolated from the enrichment of a Jinze hot spring sample which was collected from Dientan town, Tengchong county, Yunnan province, south-western PR China. Cells were Gram-stain-negative, aerobic, non-motile, rod-shaped and non-sporulating. The taxonomic position of the strain was investigated by using a polyphasic approach. Growth occurred at 37–75 °C, pH 6.0–8.0 and with 0–2.0 % (w/v) NaCl. Comparison of the 16S rRNA gene sequences indicated the strain represented a member of the genus Thermus and showed close relationships to the type strains Thermus caliditerrae YIM 77925T (96.3 % similarity) and Thermus igniterrae RF-4T (96.2 % similarity). The whole genome of CFH 72773T consisted of 2.25 Mbp and the DNA G+C content was 69.5 mol%. A total of 2262 genes, including a variety of enzymes for chemolithotrophy and anerobic respiration, were predicted. The strain had a unique negative oxidase activity and could hydrolyze starch at high temperature. Furthermore, various genes related to methane, sulfur, fumarate and nitrate metabolism were found, all these indicated that it is worth studying the novel strain. The predominant menaquinone is MK-8. The predominant cellular fatty acids included iso-C15 : 0, iso-C16 : 0 and iso-C17 : 0. The major polar lipids were comprised of aminophospholipid, glycolipid and two phospholipids. On the basis of low ANI values, different phenotypic and chemotaxonomic characters and phylogenetic analysis, we made a proposal that strain CFH 72773T represents a novel member of the genus Thermus , for which the name Thermus thermamylovorans sp. nov. is proposed. The type strain is CFH 72773T (=CCTCC AB2018244T=KCTC 43129T).

Genistein exhibits anti-diabetic and anti-lipogenic effects in mammals, however, there are rare reports on the effects of genistein on glucose and lipid metabolism in fish. This study explored the regulation role of genistein on glucose and lipid metabolism of common carp. After oral gavage with genistein (20 mg/kg body weight), the content of genistein in serum was the highest at 4 h and rapidly returned to basal values at 48 h. The blood glucose (GLU) concentrations were decreased at 24 h after gavage with genistein. The total cholesterol (TC) level was significantly down-regulated by genistein except for 24 h (P

Apelin and its receptor apj have a variety of biological functions and are involved in appetite and energy regulation. However, the comparative studies of apelin/apj system in fish are still absent. In this study, the open reading frames of apelin and apja and apjb were obtained. Apelin and apj mRNAs were widely distributed in all tissues detected, with the highest level in the brain, followed by the spleen, kidney and foregut. The mRNA expression of apelin and apjs increased rapidly at mealtime and significantly decreased after 30 min of feeding. In addition, there were obvious circadian rhythms (higher at nighttime and lower at daytime) in the expression of apelin and apja and apjb. Furthermore, fasting elevated the mRNA levels of apelin and apjs in the hypothalamus, foregut and hepatopancreas. When the 8‐day fasted fish were refed, apelin and apjs mRNA expression significantly decreased. However, there were differences in the response to fasting and refeeding between apja and apjb. The roles of apelin and its receptor apjs in fish are poorly understood. Herein, we employed molecular and physiological studies to characterize their structures, distribution and mRNA expression responses to periprandial changes and fasting–refeeding in Cyprinus carpio L. for the first time.

In this study, we assessed the effects of Radix Rehmanniae Preparata polysaccharides (RRPP) on the digestive enzymes, morphology, microbial communities and mucosal barrier function of the intestine of Luciobarbus capito. Fish were fed different amounts of RRPP (0, 0.05, 0.1, 0.2 and 0.4%) for 60 days. The results revealed that intestinal amylase and trypsin activities significantly increased after the 0.2% RRPP treatment (p

A novel Gram-staining negative, aerobic, motile by flagellum, rod-shaped bacterium, designated CFH 70021T was isolated from a hot spring soil sample collected from Tengchong, Yunnan province, PR China. Growth of CFH 70021T occurred at 15–50 °C (optimum 50 °C), pH 5.0–7.0 (optimum pH 7.0) and with 0–3.0 % (w/v) NaCl (optimum 0 %, w/v). The genome of CFH 70021T consisted of four complete circular chromosomes and five plasmids, the genomic DNA G+C content was 69.3 mol%. Comparison of the 16S rRNA gene sequences indicated that CFH 70021T represented a member of the genus Azospirillum and showed close relationship with the type strains of Azospirillum agricola CC-HIH038T (97.8 %), Azospirillum rugosum IMMIB AFH-6T (97.6 %), Azospirillum doebereinerae GSF71T (97.6 %), Azospirillum thiophilum DSM 21654T (97.4 %) and Azospirillum picis IMMIB TAR-3T (97.2 %). The polar lipids of CFH 70021T contained diphosphatidylglycerol, phosphatidylmehtylethanolamine, phosphatidylglycerol, phosphatidylcholine, two aminolipids and an unidentified phospholipid. The predominant cellular fatty acids (>10 %) included C19:0cyclo ω8c (11.4 %), C16 : 0 (27.6 %) and summed feature 8 (C18:1ω7c/C18:1ω6c, 40.9 %). The major isoprenoid quinone was Q-10. On the basis of the low ANIb result (

A novel Gram-negative bacterium, designated CFH 10530T, was isolated from the intestine of grass carp. The sample was collected from the aquaculture training base at the College of Fisheries, Henan Normal University, Xinxiang, PR China. Cells of strain CFH 10530T were coccoid, ovoid or short-rod-shaped, aerobic, non-spore-forming and non-motile. 16S rRNA gene sequence analysis demonstrated that strain CFH 10530T was closely related to Paracoccus endophyticus SYSUP0003T (97.7 % sequence similarity), Paracoccus halophilus HN-182T (96.5 %) and Paracoccus panacisoli DCY94T (96.1 %). The strain grew optimally at 25-28 °C, at pH 7.0 and with 0-2 % (w/v) NaCl. Cells were positive for catalase and oxidase, nitrate was reduced and H2S was not produced. The isoprenoid quinone was Q-10. Major cellular fatty acids were summed feature 8, C18 : 0 and C18 : 03-OH. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, one unidentified aminolipid and five unidentified polar lipids. The genome size was 3 331 229 bp with a G+C content of 69.6 mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between CFH 10530T and the other species of the genus Paracoccus were found to be below the recommended levels for species delineation (ANIm

The Chinese yam peel (CYP) is a by-product of yam processing that is rich in various nutrients and a good source for feed additives. This study investigated the effects of CYP on the intestinal microbiota and gut defence barrier of the common carp (Cyprinus carpio L.). Different groups of experimental fish were fed a normal control diet (NC), a low CYP diet (LYP) and a high CYP diet (HYP) for 8 weeks. After the feeding trial, the fish were assessed for intestinal enzyme activity, intestinal histology, immune-related gene expression, intestinal SCFAs and intestinal microbiota. Our results indicated that the intestinal integrity and antioxidant enzyme (CAT and SOD) activity in the common carp were enhanced following CYP supplementation. The mRNA levels of anti-inflammatory (TGF-β), tight binding protein (occludin and ZO-1) and pathway factor genes (TLR4 and NF-κB) were significantly upregulated in the HYP group (P＜0.05), which was accompanied by an increase in the level of pro-inflammatory IL-1β in the gut (P＜0.05). High-throughput sequencing revealed that Fusobacteria, Proteobacteria, and Bacteroidetes bacteria were most abundant in the microbial community in the gut of the common carp. The relative abundances of Bacteroides, Flavobacterium and Lactobacillus were increased, while the abundances of pathogenic microorganisms such as Enterobacteriaceae, Shewanella, Pseudomonas and Vibrio were reduced after treatment with CYP. Furthermore, the concentrations of acetic acid, propionic acid, butyric acid and total short-chain fatty acids (SCFAs) in the gut were also increased (P＜0.05). Finally, our results revealed correlations between gut microbiota, SCFAs, non-specific immunity and antioxidant enzymes in CYP-fed carp. These results suggest that CYP-supplemented feed could improve the immunity of the common carp by modulating the intestinal microflora and enhancing the gut defence barrier and has the potential to be used as an immunostimulating feed additive in aquaculture.

A novel actinobacterium, designated strain CFH 30434T, was isolated from a soil sample collected from a karst cave in Luoyang, Henan Province, PR China. The taxonomic position of the strain was investigated by using a polyphasic approach. Cells of the strain were aerobic, Gram-stain-positive, non-motile and coccoid or short rods. The strain was found to be oxidase-positive and weakly catalase-positive. Strain CFH 30434T grew optimally at 28 °C, pH 7.0–9.0 and in the presence of up to 0–1.5 % NaCl (w/v). The whole-cell sugars were glucose, mannose and rhamnose. The major isoprenoid quinone was MK-9(H8) and the major fatty acids (>10 % of the total fatty acids compositions) were anteiso-C15 : 0, iso-C15:0 and iso-C14 : 0. The polar lipids detected were diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, an unidentified phosphoglycolipid, an unidentified phospholipid and an unidentified glycolipid. The genomic DNA G+C content was determined to be 72.3 mol%. The results of phylogenetic analysis of 16S rRNA gene sequences indicated that CFH 30434T clustered within the family Promicromonosporaceae , and closely with the type strains of Xylanimicrobium pachnodae DSM 12657T, Myceligenerans crystallogenes DSM 17134T and Promicromonospora xylanilytica CCTCC AA 208046T (97.3 %, 96.2 and 95.9 % sequence similarities, respectively). Phylogenetic analysis showed that strain CFH 30434T formed a separate evolutionary branch, and was parallel to other related genera of Promicromonosporaceae . Its phylogenetic distinctiveness and distinguishing phenotypic characteristics supported that strain CFH 30434T represents a novel genus of the family Promicromonosporaceae , for which the name Antribacter gilvus gen. nov., sp. nov. is proposed. The type strain is CFH 30434T (=CGMCC 1.13856T=KCTC 49093T).

In the present study, we reported 18 LAB strains isolated from the intestinal contents of Cyprinus carpio, and their probiotic properties both in vitro and in vivo. The results showed that 9 of them had higher in vitro immunomodulatory properties, effectively survived under acidic (pH 2.5) and bile salt (ranging from 0.1% to 0.5%) conditions, and inhibited the growth of 4 pathogens. Among them, Lactococcus lactis Q-8, Lactococcus lactis Q-9, and Lactococcus lactis Z-2 showed the strongest adhesion abilities and inhibition of pathogen adhesion to mucin. When the fish consumed diets containing these 3 strains (5 × 108 CFU/g) for 8 weeks, the weight gain (WG) and specific growth rate (SGR) had significantly (P

A novel actinomycete strain, designated CFH S0054T, was isolated from a soil sample collected from Xiaokongshan in Tengchong, Yunnan Province, in south-west PR China. Phylogenetic analysis based on its 16S rRNA gene sequence indicated that strain CFH S0054T belonged to the genus Nocardia . Based on the results of 16S rRNA gene sequence analysis, strain CFH S0054T was most closely related to Nocardia concava IFM 0354T (98.3 %), Nocardia inohanensis NBRC 100128T (97.9 %), Nocardia otitidiscaviarum NBRC 14405T (97.9 %) and Nocardia heshunensis CFH S0067T (97.8 %). Strain CFH S0054T contained C16 : 0, C18 : 1 ω9c, C18 : 0 10-methyl (TBSA) and summed feature 3 as major cellular fatty acids and MK-8 (H4ω-cycl) as the major respiratory quinone. The polar lipid profile included phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and unknown phospholipids. The cell wall contained meso-diaminopimelic acid, and the whole-cell hydrolysates were arabinose, galactose, glucose, fructose, ribose and mannose. The genome of strain CFH S0054T was 7.9 Mbp with a G+C content of 68.4 mol%, the average nucleotide identity (ANI) values between strain CFH S0054T and N. concava IFM0354T were low (ANIm

This study investigated the effects of honeysuckle extract (Lonicera japonica, HE) on the growth performance and lipid metabolism of juvenile grass carp (Ctenopharyngodon idella). HE at doses of 10 g kg−1 (LHE), 20 g kg−1 (MHE), and 40 g kg−1 (HHE) were individually mixed with the basal diet and fed to grass carp for 10 weeks, and ginseng extract (20 g kg−1, GSE) was used as a positive control. The results showed that HE administration exerted no effect on growth performance, but the hepatosomatic index (HSI) and muscle and liver lipid contents were significantly decreased in the LHE and MHE groups. The serum levels of LDL-c, total triglyceride (TG) and total cholesterol (TC) also declined in the HE-treated groups. Moreover, the disordered vacuolization and nucleus migration in the liver were alleviated in the MHE and HHE groups, and mRNA expressions of lipogenesis-related genes, such as acc1, fas, srebp1, and pparγ decreased. Similarly, the expression of genes related to lipolysis, such as cpt1, atgl, lpl, and pparα, was found to be significantly increased in the MHE and HHE groups compared with the control. Taken together, HE can effectively improve the lipid metabolism and ameliorate the lipid deposition of grass carp and thus may be a promising feed additive in aquaculture.

A novel actinobacterium, designated CFH 10395T, was isolated from the foregut of grass carp (Ctenopharyngodon idella), which had been fed with ginseng extract supplement. The taxonomic position was investigated by a polyphasic approach. Cells of CFH 10395Twere Gram-staining-positive, aerobic, ovoid-shaped, non-spore-forming and non-motile. On the basis of the results of 16S rRNA gene sequence analysis, CFH 10395Twas most closely related toBrachybacterium endophyticumKCTC 49087T,Brachybacterium squillarumJCM 16464TandBrachybacterium paraconglomeratumJCM 17781T(97.85%, 97.51 and 97.29% similarity, respectively). CFH 10395Tgrew at 4–37 °C, pH 5.0–9.0 and in the presence of up to 10.0 % NaCl (w/v). The dominant menaquinone was MK-7. The whole-cell sugars were rhamnose, glucose, mannose and galactose.meso-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The major fatty acids were anteiso-C15 : 0, anteiso-C17 : 0and iso-C16 : 0. The genome size was 3.99 Mbp with a DNA G+C content of 71.9 mol%. On the basis of the results of phylogenetic analysis, physiological properties, chemotaxonomic characteristics, low average nucleotide identity (ANI) and digital DDH (dDDH) results [ANI calculated using MUMmer (ANIm) blast(ANIb) Trepresents a novel species of the genusBrachybacterium, for which the nameBrachybacterium subflavumsp. nov., is proposed. The type strain is CFH 10395T(=CGMCC 1.13804T=KCTC 49235T).

The genus Homatula belongs to the order Cypriniformes and family Nemacheilidae. Nichols (1925) set up the genus as a subgenus of Barbatula by the type species of Nemacheilus potanini. Currently, it is recognised as a valid genus. Nineteen valid species have been already reported in the drainage of the Yellow, Yangtze, Pearl, Lancang, Red and Nujiang Rivers. H. variegata, H. longidorsalis, H. berezowskii and H. potanini are distributed in the Yangtze River drainage in China. H. laxiclathra is mainly distributed in the Weihe River, a tributary of the Yellow River. The remaining species are mainly distributed in the rivers of Yunnan Province. Homatula guanheensis sp. nov., a new species, is described from the Guanhe River of the HanJiang River drainage (a tributary of the Yangtze River), Xixia County, Henan Province, China. It can be distinguished from its congeners by a combination of the following characters: the vertical brown bars on the body are wider than their interspaces, numbering 19–22; predorsal body partially scaled; the lateral line complete; adipose crest on caudal peduncle not reaching forward; the position of the anal-fin origin and the intestinal form. The new species displays distinct molecular divergence in the Cytochrome oxidase I (COI) and Cytochrome b (Cyt b) genes.

Lake Dali Nur, located in Inner Mongolia, North China, is alkaline, with Triplophysa dalaica one of the three fish species that not only survive, but thrive, in the lake. To investigate the presence of molecular mutations potentially responsible for this adaptation, the whole-genome sequence of the species was sequenced. A total of 126.5 and 106 Gb data, covering nearly 200× of the estimated genome, were generated using long-read sequencing and Hi-C technology, respectively. De novo assembly generated a genome totalled 607.91 Mb, with a contig N50 of 9.27 Mb. Nearly all whole-genome sequences were anchored and oriented onto 25 chromosomes, with telomeres for most chromosomes also being recovered. Repeats comprised approximately 35.01% of the whole genome. A total of 23,925 protein-coding genes were predicted, within which, 98.62% could be functionally annotated. Through comparisons of T. dalaica, T. tibetana, and T. siluroides gene models, a total of 898 genes were identified as likely being subjected to positive selection, with several of them potentially associated with alkaline adaptation, such as sodium bicarbonate cotransporter, SLC4A4. Demographic analyses suggested that the Dali population might have diverged from endemic freshwater Hai River populations, approximately 1 Ma. The high-quality T. dalaica genome, created in this study, not only aids in the analyses of alkaline adaptation, but may also assist in revealing the mysteries of the highly divergent genus Triplophysa in the future.

Orexins are neuropeptides involved in energy homeostasis. In fish, the function of orexin-A in glucose metabolism is less reported. The present study aims to identify the potential role of orexin-A in the glucose absorption and metabolism in common carp. The full length of orexin cDNA was cloned using RT-PCR and RACE method. The prepro-orexin cDNA was 513 bp containing an open reading frame of 474 bp and encoded 157 amino acids which including 47 amino acids of orexin-A and 28 amino acids of orexin-B. The tissue distribution results showed that orexin was expressed in multiple tissues, especially with high-level expression in hypothalamus. The exogenous orexin-A protein was chemical synthesized. Intraperitoneal injection of orexin-A alleviated the increase of plasma glucose level at 1 h and 2 h after OGTT (Oral glucose tolerance test). Orexin-A also decreased glucose uptake activity and the expression of sglt1 and glut2 mRNA in intestine. However, orexin-A significantly increased the mRNA expression of glut2 in liver and glut4 in muscle. Moreover, the gluconeogenesis-related gene fbpase mRNA was significantly down-regulated, while glycolysis-related genes gk and hk were significantly up-regulated after treatment with orexin-A in vivo and vitro. These results implied that hyperglycemia could be alleviated in common carp after the injection of orexin-A and suggest a role of this peptide as a plasma glucose regulator by inhibition glucose absorption in intestine, promotion glucose transport to liver and muscle. Furthermore, hepatic gluconeogenesis was inhibited. Taken together, this study helped to understand the characterization of prepro-orexin and the function of orexin-A in fish glucose homeostasis.

Recently, the concept of precision nutrition has emerged in aquaculture, and there is increasing discussion on this topic. Some researchers have defined precision nutrition as precision feeding, which means that the nutrient contents of feed should meet the requirements for an animal’s optimal production performance and achieve minimum fodder waste at the same time. In practice, precision nutrition should include a comprehensive survey of the animal’s genetic background, living habits, metabolic characteristics, water ecological environment and other factors. Precision nutritional regulation covers every level, from genes, cells, and tissues to the whole organism. Through interacting with genes, nutrients activate or inhibit signalling pathways/networks within cells, which regulate gene expression and protein synthesis and subsequently affect the composition, content and deposition sites of carbohydrates, lipids, proteins and trace elements. Therefore, we propose that precision nutritional intervention needs to be carried out from the perspectives of ‘precision feeding’, ‘precision metabolism’, ‘precision output’ and ‘precision support’ simultaneously. This review intends to elaborate the concept evolution, theoretical system, and composition of the technical system, together with other aspects of precision nutritional regulation. This knowledge will provide a theoretical reference for the sustainable development of the aquaculture industry and the harvesting of quality products.

Since discovery, glucagon biology has remained enigmatic. Studies have shown that glucagon may have physiological effects beyond glucose regulation by binding to its receptor (Gcgr). The potential roles of glucagon and its receptor in the crosstalk between glucose metabolism and immune function of fish remain to be investigated. In the present study, we sequenced and characterized gcgra and gcgrb in grass carp. Phylogenetic analysis showed that they were highly homologous with their counterparts in fish. The gcgra and gcgrb mRNAs were ubiquitously expressed in all the tissues examined. The gcgra mRNA was highly expressed in the liver and gcgrb was mainly expressed in the liver and brain regions of grass carp. Furthermore, the results of oral glucose tolerance test (OGTT) showed that the expression levels of the two receptors were significantly increased at 12 h after treatment. In the hepatocytes, insulin inhibited gcgra and gcgrb mRNA expressions at 3−12 h and 6−12 h, respectively. While glucagon promoted their expressions at 3−12 h and 3 h, respectively. Intraperitoneal injection of lipopolysaccharide (LPS) increased hepatic gcgra mRNA level at 6 h post treatment, and up-regulated gcgrb mRNA abundance in the liver at 24 h. In response to polyinosinic polycytidylic acid [poly (I:C)] stimuli, however, gcgra and gcgrb mRNA levels were decreased. These results suggested that glucagon receptors were affected by bacterial-like and virus-like infection beyond their roles in the glucose metabolism of grass carp.

The present study assessed the effects of different ratios of dietary linolenic acid (LNA) to linoleic acid (LA) from vegetable oils on growth performance, ovarian steroidogenesis, plasma sex steroid hormone, and tissue fatty acids accumulation in juvenile common carp (Cyprinus carpio). With fish oil, peanut oil, and perilla oil as lipid source, five experimental diets containing 32% crude protein and 8% crude lipid were formulated with LNA/LA ratios of 0.97 (control diet), 0.02, 0.46, 1.09, and 1.53, respectively. The diets were assigned to 15 tanks (50 L) of carp, and the fish (8.10 ± 0.11 g, n = 25) were manually fed to apparent satiation twice daily in triplicate groups for 16 weeks. The survival rate and feed conversion ratio were not significantly different among treatments (P > 0.05). Results demonstrated that fish fed diet with LNA/LA ratio of 1.09 exhibited the highest body weight gain, and was no significantly different with fish fed control diet. Fish fed diet with LNA/LA ratio of 1.53 showed the highest gonadosomatic index (P < 0.05). The expression of StAR, 17β-HSD and Cyp19a1a in ovary were up-regulated, and plasma E2 increased with increasing of dietary LNA/LA ratios (P < 0.05). Fish fed diet with LNA/LA ratio of 0.02 showed the lowest plasma E2 and T. The expression of Fads6-a and Elovl5-a in liver expressed higher in fish fed with dietary LNA/LA ratio of 1.09. LNA, LA, Docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) contents in liver were significantly affected by dietary LNA/LA ratios. LNA content in liver and LNA and ARA content in ovary increased with the increasing of dietary LNA/LA ratios. Results of this study indicated that dietary LNA/LA ratios alter both growth and ovarian development, and provided evidence that balanced LNA/LA ratio was beneficial for growth and ovarian development of juvenile common carp.

Abnormal lipid metabolism in the liver due to excessive fat accumulation is a widespread problem in fish. MicroRNA-122 (miR-122), a liver-specific miRNA in vertebrates, is involved in lipid metabolism. In this study, miR-122 was cloned, and its function was investigated in grass carp. MiR-122 is 99 bp in length, showing 70 % similarity to that of other species and is specifically expressed in liver tissue. After transfection with miR-122 agomir for 24 h in liver cells, we found that the overexpression of miR-122 significantly increased the TG content in cells (P < 0.05), while the expression level of transcription factors related to lipid synthesis was significantly increased (P < 0.05). After injection of miR-122 agomir in vivo, the TG content in the liver increased significantly (P < 0.05), and the mRNA expression of lipid synthesis-related genes (PPARγ, SREBP-1c, ACC, FAS and H-FABP) increased significantly (P < 0.05). The relative expression of the proinflammatory factors TNF-α, IL-6, and IL-1β also increased significantly (P < 0.05), while the relative abundance of the anti-inflammatory factors IL-10 and TGF-β1 decreased significantly (P < 0.05). In addition, we found that miR-122 regulated lipid catabolism-related genes through AMPK, and AMPK may regulate lipid synthesis-related genes through miR-122 directly or indirectly. In summary, the comparison of miRNA-122 from genomic sequences reveals strong conservation of miRNA-122 across vertebrate classes; however, its function shows species-specific actions in grass carp and mammalian models. This study provides basic data for further investigation of a miRNA related to fatty liver and other metabolic diseases.

A novel Gram-stain-negative, aerobic, non-motile, coccus-shaped bacterium, designated CFH 90064T, was isolated from a salt lake sediment sample collected from Yuncheng city, Shanxi province, PR China. 16S rRNA gene sequence comparisons and phylogenetic analyses showed that the strain belonged to the genus Paracoccus and clustered with Paracoccus zeaxanthinifaciens R-1512T (98.2 % similarity), Paracoccus homiensis DD-R11T (97.6 % similarity) and Paracoccus fistulariae 22–5T (96.5 % similarity), respectively. Growth of strain CFH 90064T was observed at 10–37 °C, pH 6.0–9.0 and with NaCl concentrations of up to 6.0 % (w/v). Strain CFH 90064T contained Q-10 as the only isoprenoid quinone, and the major fatty acid was C18 : 1ω7c. Polar lipids of strain CFH 90064T comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an unidentified glycolipid, an unidentified aminolipid and an unidentified phospholipid. The genome of strain CFH 90008T was 3.75 Mbp with a DNA G+C content of 65.1 %. Based on the phylogenetic analyses, low average nucleotide identity results, chemotaxonomic characteristics and differential physiological properties, strain CFH 90064T could not be classified into any recognized species of the genus Paracoccus , suggesting that this strain represents a novel species, for which the name Paracoccus halotolerans sp. nov. is proposed. The type strain is CFH 90064T (=CCTCC AB 2016131T=DSM 103234T).

Luteinizing hormone-releasing hormone analog (LHRH-A) and dopamine inhibitors have been widely used to induce oocyte maturation and ovulation in domesticated fishes. Although this approach represents a reliable method for regulating fish reproduction, the underlying molecular mechanisms mediating LH action are largely unexplored. The objective of this study was to determine the transcriptional profile of gene programming in hormone-treated common carp. In the present study, female common carp were intraperitoneally injected with LHRH-A together with dopamine inhibitors, and control fish were injected with saline. Ovarian morphological changes were analysed by both light microscopy and scanning electron microscopy. Furthermore, gene expression profiling of the brain and ovarian tissues was performed by Illumina sequencing. Compared to the control carp, hormone treatment resulted in morphological changes including disappearance of nuclear membrane, breakdown of germinal vesicle (GVBD), and fusion of yolk globules, reflecting that hormones significantly promoted oocyte maturation. In comparison to control, we have identified 867 and 9,053 differentially expressed genes in the hormone-treated female brain and ovary, respectively. In the brain, most of the identified genes were significantly enriched in 18 KEGG pathways. In the ovarian tissue, the identified genes were significantly involved in 9 pathways. In the hormone-treated carp, genes were involved in calcium signalling pathway, cAMP signalling pathway, insulin secretion, and oxidative phosphorylation pathway, which showed obvious associations with ovarian maturation. The present study provides transcriptomic information for hormone-treated carp, which might be useful for studying the endocrine regulation and mechanisms of ovarian maturation in domesticated fishes.

A Gram-stain-positive, aerobic, motile with peritrichous flagella, rod-shaped bacterium, designated CFH S0170T, was isolated from a soil sample collected from Catba island in Ha Long Bay, Hai Phong City, Vietnam. Comparison of the 16S rRNA gene sequences showed that strain CFH S0170T belonged to the genus Paenibacillus and showed closest relationship with Paenibacillus vulneris CCUG 53270T (98.1 % similarity). Phylogenetic analysis demonstrated that the novel candidate formed a coherent branch with P. vulneris CCUG 53270T and Paenibacillus yunnanensis YN2T. Furthermore, the novel strain shared 87.2 % rpoB gene sequence similarity with P. vulneris CCUG 53270T. Growth of strain CFH S0170T occurred at 10–40 °C, pH 6.0–8.0 and with 0–2.0 % (w/v) NaCl. Strain CFH S0170T contained mannose, glucose and rhamnose as the major whole-cell sugars. The cell-wall peptidoglycan contained meso-diaminopimelic acid, glutamic acid, lysine and aspartic acid. The polar lipid profile contained diphosphatidylglycerol, phosphatidylethanolamine, glycolipids and phospholipids. The dominant cellular fatty acids included anteiso-C15 : 0 and C15 : 0. The genomic DNA G+C content was 50.9 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic analysis, strain CFH S0170T is affiliated to the genus Paenibacillus , but could be distinguished from other valid species of this genus. It is concluded that strain CFH S0170T should be considered to represent a novel species of the genus Paenibacillus , for which the name Paenibacillus esterisolvens sp. nov. is proposed. The type strain is CFH S0170T (=KCTC 33624T=BCRC 80802T).

As the incretin hormone, Glucose-dependent insulinotropic peptide (GIP) plays an important role in lipid metabolism, glucose uptake, and bone metabolism in mammals. To evaluate the roles of GIP in the teleost, the gip gene was isolated from the foregut of grass carp by RT-PCR. The ORF of grass carp gip was 327 bp and encodes 108 amino acids. And the mature peptide of grass carp was 31 amino acids. The tissue distribution results showed that gip mRNA was highly expressed in the gut, and was also at high levels in the spleen and brain region. In the oral glucose tolerance test (OGTT), the gip expression was significantly increased in foregut by glucose treatment for 1 and 3 h. The primary hepatocytes and intraperitoneal injection studies showed that the glut2, g6pase, pepck, acc1, fas, hsl, lpl expression were increased and the gk and cpt1 expression were decreased by GIP treatment. And the expression of pi3k, akt and pka were also increased by GIP treatment. In the primary hepatocytes, the effects of GIP on g6pase, glut2, lpl and cpt1 expression were relieved by Wortmannin (PI3K inhibitor), and the effects of GIP on pepck, gk and hsl expression were alleviated by H89•2HCl (PKA inhibitor). And glucose and triglyceride (TG) contents are promoted in primary hepatocytes by GIP treatment. In the intraperitoneal injection experiment, the serum glucose, total cholesterol (T-CHO) and low-density lipoprotein cholesterol (LDL-C) contents were reduced, and serum TG and high-density lipoprotein cholesterol (HDL-C) contents were elevated after GIP injection. Our studies for the first time unveil the potential role of GIP as a regulatory factor of glucose and lipid metabolism in teleost.

Based on beneficial effects of Lactococcus spp. and their extracellular polysaccharides on common carp (Cyprinus carpio L.) in previous studies, the main purpose of this paper was to investigate the functions of single or multi-strains of Lactococcus spp. on the growth performance, glucose absorption and metabolism of common carp. The results showed that when the fish consumed diets containing single (Lactococcus lactis Q-8, L. lactis Q-9, L. lactis Z-2) or multi-strains of Lactococcus spp. (5 × 108 CFU g−1 of feed) for 60 days, the final weight, weight gain (WG), specific growth rate (SGR) and condition factor (CF) had significantly (P .05). For the glucose absorption, Lactococcus spp. addition groups significantly increased the blood glucose concentration and up-regulated the expression of Sglt1 and Gult2 in intestine compared with the control group (P

The co-transport of sodium and glucose is the first step for intestinal glucose absorption. Dietary glucose and sodium chloride (NaCl) may facilitate this physiological process in common carp (Cyprinus carpio L.). To test this hypothesis, we first investigated the feeding rhythm of intestinal glucose absorption. Carps were fed to satiety once a day (09:00 a.m.) for 1 month. Intestinal samples were collected at 01:00, 05:00, 09:00, 13:00, 17:00 and 21:00. Result showed that food intake greatly enhanced sodium/glucose cotransporter 1 (SGLT1) and glucose transporter type 2 (GLUT2) expressions, and improved glucose absorption, with highest levels at 09:00 a.m.. Then we designed iso-nitrogenous and iso-energetic diets with graded levels of glucose (10%, 20%, 30%, 40% and 50%) and NaCl (0%, 1%, 3% and 5%), and submitted to feeding trial for 10 weeks. The expressions of SGLT1 and GLUT2, brush border membrane vesicles (BBMVs) glucose transport and intestinal villus height were determined after the feeding trial. Increasing levels of dietary glucose and NaCl up-regulated mRNA and protein levels of SGLT1 and GLUT2, enhanced BBMVs glucose transport in the proximal, mid and distal intestine. As for histological adaptive response, however, high-glucose diet prolonged while high-NaCl diet shrank intestinal villus height. Furthermore, we also found that higher mRNA levels of SGLT1 and GLUT2, higher glucose transport capacity of BBMVs, and higher intestinal villus were detected in the proximal and mid intestine, compared to the distal part. Taken together, our study indicated that intestinal glucose absorption in carp was primarily occurred in the proximal and mid intestine, and increasing levels of dietary glucose and NaCl enhanced intestinal glucose absorption in carp.

Anti-Mullerian hormone (AMH) has been suggested to play critical roles in male sex differentiation and testicular development among different vertebrates. However, growing evidence suggests that it also plays a key role in female reproduction. In the present study, we cloned the Amh gene and examined its expression pattern in a teleost species, spotted steed. Furthermore, recombinant AMH was produced and incubated with adult ovarian fragments of spotted steed in vitro. The results showed that the open reading frame (ORF) of spotted steed Amh is 1671 bp in length, encoding 556 amino acids. qPCR and western blot analysis showed that Amh had the highest expression during the vitellogenesis and maturation stages. Using recombinant AMH, we further showed that AMH significantly increased germinal vesicle breakdown (GVBD) rates, Cyclin B expression and maturation-promoting factor (MPF) level in vitro. In addition, treatment of oocytes with AMH decreased Cyp19a1a expression and E2 production. These results suggested that AMH may promote oocyte maturation in spotted steed.

Basing on the beneficial effects of live Lactococcus lactis Z-2 and its extracellular polysaccharides on the common carp (Cyprinus carpio L.) in the previous studies, the present study aims may be appropriate to investigate the functions of other forms of L. lactis Z-2 (namely, heat-killed or cellular components) on the intestinal tract, blood and hepatopancreas of common carp. 480 fish [(42.35 ± 0.76) g] were treated with different preparations of L. lactis Z-2 for 7 days and infected with Aeromonas hydrophila for 24 h, following which to detect the levels of NO and cytokines, the activities of lysozyme (LZM) and alkaline phosphatase (AKP) in the serum, the antioxidants (T-AOC, SOD, CAT, GSH, GSH-Px and MDA) in hepatopancreas, the digestive enzymes and the gene expression of nutrient transporters in intestinal. Prior to infection, different treatment groups significantly enhanced NO production, the levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), AKP activity, antioxidant content (T-AOC, SOD, CAT, and GSH), and reduced MDA level compared to those in the negative control group (P

As the major non-protein energy sources, high carbohydrate (CHO) and lipid (L) diets have been widely used in aquaculture to reduce cost, but they also caused excessive lipid accumulation in the fish liver. It is not yet clear which, lipid or carbohydrate, is a greater influence on hepatic lipid accumulation. To study the effects of dietary carbohydrate and lipid levels on hepatic lipid deposition in Nile tilapia ( Oreochromis niloticus ), six diets with different carbohydrate and lipid levels (carbohydrate level ranged from 11.2% to 54.24%, while lipid level ranged from 21.51% to 2.70%, namely, the dietary CHO:L ratios ranged from 0.52:1 to 20.09:1) were formulated and fed to tilapia for 8 weeks. After the feeding trial, high specific growth rate (SGR) was observed in the groups with the CHO:L ratio of 1.95, 3.41 and 6.40. Hepatosomatic and viscerosomatic index increased as dietary CHO:L ratios increased. Low serum TG, CHL and HDL levels was observed in the groups with the CHO:L ratio of 6.40 and 20.09. Hepatic histology showed that the fish fed with dietary CHO:L ratios of 3.41 and 6.40 have more hepatic lipid droplets than fish fed with other diets. Hepatic gene expression data indicated that the cd36 transcript levels were significantly affected by dietary CHO:L ratios, with the highest expression in fish fed D4 and D5 with CHO:L ratio of 3.41 and 6.40. Higher transcript levels of lipogenic genes ( fas , acc-α and dgat2 ) were observed in the liver of fish fed with high CHO:L ratio diets, whereas FA β-oxidation genes ( cpt1 and acox1 ) expression were depressed in liver. Hepatic apoB100 expression was also down-regulated with the high dietary CHO:L ratios. These results suggested that dietary carbohydrates have a stronger effect on hepatic lipid accumulation than dietary lipids in tilapia. High dietary CHO:L ratios (> 3.41) accelerated the hepatic lipid deposition by increasing de novo lipogenesis and reducing FA β-oxidation and lipoprotein clearance in the liver, and diet with around 1.95 CHO:L ratio is suitable for tilapia culture concerning the growth performance and health. The present results will be of great significance in improving the utilization of dietary lipid and carbohydrate to achieve better nutrition efficiency in tilapia.

The Peptide Transporter 1 (PepT1) plays an important role in animal protein nutrition. This is a low-affinity/high-capacity, stereoselective transmembrane transporter that mediates the uptake of a fraction of dietary amino acids in their di- and tripeptide forms. PepT1 is highly expressed in the intestines of vertebrates and the current studies examining PepT1 function have concentrated mostly on mammals and less emphasis has been placed on protein nutrition in fish. In the gastrointestinal track, amino acids are absorbed more efficiently in the form of small peptides than as free amino acids suggesting a potential role of PepT1 in the optimization of amino acid absorption which is relevant for fish nutrition. Therefore, this review focused on the physiological characteristics, structures, tissue distribution and expression of PepT1 transcripts and regulation of PepT1 protein in fish.

Rahnella aquatilis infection is rare in aquaculture. Here, a Gram-negative rod-shaped bacterium was isolated from diseased crucian carp Carassius auratus in Xuzhou City, Jiangsu Province, eastern China. The isolate was tentatively named strain KCL-5, and subsequently identified as R. aquatilis by biochemical properties and molecular techniques. The results showed that the isolate KCL-5 was most closely related to the type strain ATCC33071 (= DSM4594) of R. aquatilis, which shared 99.67, 96.26 and 99.58% nucleotide sequence identities for 16S rDNA, gyrB and toxin yhaV genes, respectively. Experimental challenges were conducted which demonstrated pathogenicity of the isolate in crucian carp. Antimicrobial susceptibility testing showed that the isolated strain was susceptible to piperacillin, gentamicin, kanamycin, nalidixic acid, norfloxacin, ofloxacin, azithromycin and erythromycin. To our knowledge, this is the first report on R. aquatilis infection in crucian carp, and the first evidence of pathogenicity in fish.

The distribution of fat among both invertebrate and vertebrate groups is heterogeneous. Studies have shown that fatty acid‐binding proteins (FABPs), which mainly bind and transport fatty acids, play important roles in the regulation of fat storage and distribution. However, the systematic and genome‐wide investigation of FABP genes in organisms with a heterogeneous fat distribution remains in its infancy. The availability of the complete genomes of Caenorhabditis elegans, Callorhinchus milii, and other organisms with a heterogeneous fat distribution allowed us to systematically investigate the gene structure and phylogeny of FABP genes across a wide range of phyla. In this study, we analyzed the number, structure, chromosomal location, and phylogeny of FABP genes in 18 organisms from C. elegans to Homo sapiens. A total of 12 types of FABP genes were identified in the 18 species, and no single organism exhibited all 12 fatty acid‐binding genes (FABPs). The absence of a specific FABP gene in tissue may be related to the absence of fat storage in the corresponding tissue. The genomic loci of the FABP genes were diverse, and their gene structures varied. The results of the phylogenetic analysis and the observation of conserved gene synthesis of FABP family genes/proteins suggest that all FABP genes may have evolved from a common ancestor through tandem duplication. This study not only lays a strong theoretical foundation for the study of fat deposition in different organisms, but also provides a new perspective regarding metabolic disease prevention and control and the improvement of agricultural product quality., To clarify the relationships between fatty acid‐binding proteins (FABPs) and the tissues in which fat is deposited, the number, gene structure, conserved synteny, and evolution of FABP family genes in 18 species were systemically studied. In total, 142 FABPs were identified. The absence of a specific FABP gene in tissue may be related to the absence of fat storage in the corresponding tissue.

Glucose transporter 2 (glut2) has been studied in mammals, aves, and several fish, while the comparative studies of glut2 in common carp are still lacking. In this study, glut2 was firstly isolated and characterized from the liver of common carp. The full-length cDNA of glut2 was 2351 bp with an open reading frame (ORF) of 1512 bp, encoding 503 amino acids. Alignment of glut2 amino acid sequences from different species revealed that common carp glut2 showed higher sequence identity with teleosts, and lower homology with mammals and amphibians. Tissue distribution demonstrated that glut2 mRNA level was mainly expressed in liver, foregut, and midgut. To investigate the actions of glut2 on glucose metabolism, the level of glut2 mRNA was detected after intraperitoneal injection of glucose, human insulin and glucagon (100 ng/g), respectively. Following glucose administration, glut2 gene expression was significantly upregulated at 3 h in the foregut. However, no change was found in hepatic glut2 mRNA level, indicating that glut2 may have a role in intestinal glucose uptake rather than in the liver. Following insulin treatment, the expression of glut2 was markedly downregulated at 3 h and 6 h in the liver, and at 3 h in the foregut, respectively. Furthermore, glut2 mRNA expression was unaffected by glucagon injection in the liver and foregut. These results suggested that the expression of glut2 regulated by pancreatic hormones was different. Taken together, our studies firstly revealed the structure of the glut2 gene and its potential functions in glucose metabolism of common carp.

Microbial exopolysaccharides (EPS) from Lactococcus have been found to have an important role in the probiotic activity of this bacterium; however, the immunomodulatory and antioxidant activities have not been fully explored in aquaculture. In the present study, we investigated EPS-2 from Lactococcus lactis Z-2, isolated from healthy common carp, for its immunomodulatory and antioxidant effects and disease resistance against Aeromonas hydrophila in Cyprinus carpio L. We found that the molecular weight of EPS-2 was 18.65 KDa. The monosaccharide composition of this polymer was rhamnose, xylose, mannose, glucose, and galactose at a molar percentage of 13.3%, 14.1%, 18.5%, 27.4%, and 26.7%, respectively. EPS-2 treatment could modulate the immune responses in vitro and in vivo. In vitro tests showed that EPS-2 could significantly enhance the proliferation and phagocytosis activities (P

To explore the mechanism of fatty liver formation induced by high non-protein energy diets in grass carp (Ctenopharyngodon idella), basal diet and high-energy diets were fed to juvenile grass carp for 9 weeks. The experimental groups fed on high-energy diets which included a high-lipid diet (H-LIP), a high-carbohydrate diet (H-CHO) and a high-lipid and carbohydrate diet (H-CL). The control group fed on basal diet. Growth performance, liver fat accumulation, serum biochemical indexes and the expression levels of lipid metabolism-related genes (SREBP-1, PPARγ, FAS, ACC1, and LPL) and miRNAs (miR-33, miR-122, and miR-370) were examined at the end of the feeding trial. There were no significant differences in growth rate and feed efficiency among the four groups. However, significant increase in mesenteric and liver fat contents, and lipid droplets in the liver was induced by high-lipid and high-carbohydrate diets. There were significant differences in serum biochemical indicators such as AST/ALT, GLB, TG and TP, and liver fatty acid composition between the control and experimental groups. The expression levels of SREBP-1, PPARγ, FAS, ACC1 and LPL were upregulated, while CPT-1 was downregulated with the high-energy treatments. Additionally, the expression levels of miR-33, miR-122 and miR-370 in the liver were higher in the three high-energy treatments than those in the control (P

An endophyte with high yield of β-mannanase, designated as Paenibacillus sp. CH-3, was isolated from black locust (Robinia pseudoacacia) seeds. The β-mannanase gene (manB) has been cloned, expressed, purified, and characterized. With an open reading frame of 984 bp, the manB gene encodes 327 amino acid residues, which belongs to GH family 5. The recombinant β-mannanase (ManB) has an apparent molecular weight of 50.4 kDa with an optimal activity level at pH 7.0 and 45 °C, and it is stable in the range of pH 4-9. By optimizing, the temperature, isopropyl β-d-thiogalactoside concentration, and induction time were 28 °C, 0.05 mM, and 12 H, respectively. The highest activity reached at 1,054.17 U/mL. In addition, ManB had Km values of 7.30, 8.69, and 27.17 mg/mL for locust bean gum (LBG), guar gum, and konjac glucomannan (KGM), respectively. Its catalytic efficiency (kcat /Km ) was 176.31 mL/(mg·Sec) for LBG, 116.69 mL/(mg·Sec) for guar gum, and 115.49 mL/(mg·Sec) for KGM. The products of glucomannans, which were hydrolyzed by ManB, mainly contain mannobiose, mannotetrose, and a higher manno-oligosaccharide. The characteristics of ManB revealed that it could be exploited as an effective additive in the animal feed industry.

Two closely related thermophilic bacterial strains, designated YIM 78023T and YIM 78058, were isolated from samples collected from two alkaline hot springs in Tengchong county, Yunnan province, south-west China. The novel isolates were Gram-stain-negative, non-motile, aerobic ovoid- to coccoid-shaped and non-spore-forming. Strain YIM 78023T grew at 20-60 oC and pH 6.0-9.0 with optimal growth observed at 40-50 oC and pH 8.0, while strain YIM 78058 grew at 25-60 oC and pH 6.0-10.0 with optimal growth at 45-50 oC and pH 8.0. Phylogenetic analysis based on 16S rRNA gene sequences affiliated these two isolates within the family Acetobacteraceae with high sequence similarities to members of the genera Roseomonas and Belnapia (all sequence similarities

Stimulator of interferon gene (sting) was identified and characterized from common carp Cyprinus carpio. The sting messenger (m)RNA encoded a polypeptide of 402 amino acids with a calculated molecular mass of 46·184 kDa and an isoelectronic point of 6·08. The deduced protein of sting contained a signal peptide, three transmembrane motifs in the N-terminal region and four putative motifs (RXR) found in resident endoplasmic reticulum proteins. mRNA expression of sting was present in twelve investigated tissues, and was up-regulated by koi herpesvirus (KHV) in vivo and in vitro. The transcription of sting was altered by poly(I:C) and poly(dT:dA) stimulation in vitro. The findings suggested that sting is an inducible gene involved in innate immunity against DNA- and RNA-derived pathogens. To investigate defence mechanisms in C. carpio development, sting level in embryos, larvae and juvenile fish was monitored following KHV challenge. The sting message was negligible in embryos prior to hatching, but observed at higher transcriptional levels throughout larval and juvenile stages. Investigation showed the mRNA expression profiles of genes encoding for proteins promoting various functions in the interferon pathway, from pattern recognition receptors to antiviral genes, to be significantly induced in all examined organs by in vivo infection with KHV. Following KHV infection, the ifn message was significantly downregulated in spleen, head kidney, brain and hepatopancreas but notably up-regulated in gill, intestine and skin, suggesting that ifn induction might be related to the mucosal immune system and virus anti-ifn mechanisms. These results provided the basis for further research into the role and mechanisms of sting in fishes.

This study evaluated the effects of dietary Clostridium butyricum on intestinal enzyme activity, intestinal histology, immune-related gene expression, short-chain fatty acids and intestinal microbiota in common carp (Cyprinus carpio L.). Three hundred and sixty fish (89.89 ± 0.77 g) were divided into three groups and fed a diet supplemented with C. butyricum at 0, 0.125% (0.25 × 107 CFU/g), or 0.5% (1 × 107 CFU/g) (denoted as NC, LCB and HCB, respectively) for 8 weeks. Compared with the NC group, growth performances were not affected by adding C. butyricum. The enzyme activity of catalase (CAT) and lysozyme (LZM) in the intestine of the HCB group were significantly enhanced, and the butyric acid and propionic acid content in both C. butyricum-treated groups increased. In the HCB group, mucin secretion and the height of the epithelium microvilli were obviously increased, and the mucosal folds were deeper and smoother. The intestinal gene expression of IL-10, TLR-2, MyD-88, ZO-1 and Occludin were significantly higher in the HCB group than that in the control group but not in the LCB group. Dietary C. butyricum increased the diversity of the intestinal microbiota of common carp. At the phylum level, the abundance of Bacteroidetes improved concomitantly with a significant decrease in the abundance of Fusobacteria and Proteobacteria. At the genus level, the relative abundance of the beneficial bacteria Bacteroides and Cetobacterium increased remarkably in the HCB group, and pathogens such as Aeromonas, Vibrio, and Pseudomonas were inhibited. In conclusion, the results from this study indicate that supplementing the diet with C. butyricum at an appropriate dose can improve the intestinal immunity of common carp by regulating the intestinal microbiota and improving the defence function of the intestinal barrier.

Apelin, a kind of active polypeptide, has many biological functions, such as promoting food intake, enhancing immunity, and regulating energy balance. In mammals, studies have indicated that apelin is involved in regulating food intake. However, there are relatively few studies about the regulatory effect of apelin on fish feeding, and the specific mechanism is not clear. Therefore, the purpose of this study was to preliminarily investigate the regulatory effects of apelin on key genes of feeding and growth in common carp (Cyprinus Carpio L.) through in vitro and in vivo experiments. In the present study, after incubation with different concentrations of Pyr-apelin-13 (0, 10, 100, and 1000 nM) in hypothalamic fragments, the expressions of Neuropeptide Y (NPY) and Agouti related peptide (AgRP) mRNA were significantly up-regulated at 12 and 3 h, respectively, and the significant down-regulation of Cocaine and amphetamine-related transcript (CART) mRNA expression was observed at 1 and 3 h. In vivo, after Pyr-apelin-13 oral administration (0, 1, 10, and 100 pmol/g), the orexin mRNA level in the hypothalamus of common carp was significantly increased at 1, 6, and 12 h, while CART/(Proopiomelanocortin) POMC mRNA levels in the hypothalamus of common carp were significantly down-regulated. Following incubation with different concentrations of Pyr-apelin-13 (0, 10, 100, and 1000 nM) in primary hepatocytes, GHR (Growth hormone receptor), IGF2 (Insulin-like growth factor 2), IGFBP2 (Insulin like growth factor binding protein 2), and IGFBP3 (Insulin like growth factor binding protein 3) mRNA levels were significantly increased at 3 h. In vivo, the levels of IGF1 (Insulin-like growth factor 1), IGF2, IGFBP2 (Insulin like growth factor binding protein 2), and IGFBP3 mRNA were significantly increased after the oral administration of Pyr-apelin-13 in the hepatopancreas, in a time and dose-dependent manner. These results support the hypothesis that Pyr-apelin-13 might regulate the feeding and growth of common carp through mediating the expressions of appetite- and growth-related genes. Overall, apelin, which is an orexigenic peptide, improves food intake and is involved in the growth of common carp.

In order to study the effects of replacement of soybean meal (SM) with defatted black soldier fly larvae meal (BSFLM) in grass carp production practice, juvenile grass carps with initial body weight of (10.10 ± 0.28) g were selected for subsequent tests. Five isolipidic (49.1–50.3 g kg−1) and isonitrogen (321.4–327.8 g kg-1) experimental diets were formulated by replacing 0 % (SM), 25% (BSFLM25), 50% (BSFLM50), 75% (BSFLM75) and 100% (BSFLM100) of SM with BSFLM, respectively. After 56 days of feeding, the changes of growth performance, body composition, serum biochemical indexes, antioxidant capacity, digestive enzyme activity, intestinal and liver tissue structure, and intestinal microbiota of grass carp were detected. The results showed that there were no significant differences in growth, feed efficiency and muscle proximate compositions among the treatment groups. The BSFLM100 group had significantly higher TG content than the other groups. Catalase activity was significantly increased in BSFLM25 and BSFLM50 groups compared with that in the SM group. The activities of amylase and lipase in BSFLM50, BSFLM75, and BSFLM100 groups were lower than the control group. Compared with the SM group, the intestinal villi length and the thickness of the intestinal wall of BSFLM75 and BSFLM100 groups were decreased. Gut microbiota analysis showed no significant changes in the operational taxonomic unit (OTU) diversity and richness indices among treatments. However, the abundance of Aeromonas and Shewanella decreased significantly after substitution with BSFLM. These results show that there was no negative effect on growth performance and improved the antioxidant capacity of grass carp when dietary SM complete replacement by BSFLM. However, when the replacement level exceeds 50 %, intestinal histomorphology may be damaged.