An 8-week feeding trial was conducted to determine the effects of dietary taurine supplementation on growth performance, activities of digestive enzymes, antioxidant status and the target of rapamycin (TOR) gene expression in black carp (initial body weight 5.94 ± 0.02 g) fed with low fish meal diet. Six isonitrogen and isolipidic diets were formulated. High fish meal-based diet (HFM) contained 20% fish meal and 24% soybean meal as a positive control. Fifty per cent of fish meal in HFM was replaced by soybean meal and were supplemented with 0, 0.05%, 0.1%, 0.2% and 0.4% dietary taurine respectively (designated as T 0.00 (a negative control), T 0.05 , T 0.1 , T 0.2 and T 0.4 ). The results showed that the partial replacement of fish meal by soybean meal without taurine supplementation resulted in a significant reduction in weight gain (WG), activities of amylase and lipase in intestine, superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) in serum, with a significant increase in feed conversion rate (FCR), the content of malonaldehyde (MDA), triglyceride (TG) and total cholesterol (TC) in serum. WG in groups supplemented with equal or above to 0.1% dietary taurine was significantly higher compared with T 0 group.With increasing levels of dietary taurine, the activities of amylase, lipase, GSH-px and SOD and glutataione (GSH) content significantly increased (p < 0.05). FCR, the content of MDA, TG and TC in serum and crude lipid content in whole body were significantly reduced after taurine treatment (p < 0.05). In liver, TOR mRNA expression in groups with equal or above to 0.1% taurine was significantly higher than T 0 group (p < 0.05). K E Y W O R D Santioxidant status, black carp, digestive enzymes, growth, taurine

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In this work, we reported the complete mitochondrial genome of Corydoras duplicareus. The total length of the mitochondrial genome is 16,667 bp, with the base composition of 32.90% A, 26.55% T, 25.94% C, and 14.61% G. It contains two ribosomal RNA genes, 13 protein-coding genes, 22 transfer RNA genes, and a major non-coding control region (D-loop region). The arrangement of these genes is the same as that found in the Siluriformes. All the protein initiation codons are ATG, except for cox1 that begins with GTG. The cytochrome c oxidase subunit I (COX1) amino acid sequence of C. duplicareus and other 27 species from 8 genera were used for phylogenetic analysis by maximum likelihood method. The topology demonstrated that all species are divided into two groups (Callichthyidae and Cyprinidae), and the C. duplicareus was clustered with C.nattereri.

ABSTRACT. The aim of the study was to investigate the grass carp hemorrhagic infection pathway and its key-related genes. Grass carp reovirus (GCRV) might cause hemorrhagic disease in grass carps. Healthy grass carp fingerlings (N = 60) were divided into control and infected groups. Fish in the control group were intraperitoneally (ip) injected with 0.6% fish physiological saline; the infected group received 5,000,000 50% tissue culture infective doses of GCRV 873 standard strain, a double-stranded RNA (dsRNA) virus strain, ip, in 0.5 mL. Illumina HiSeq TM 2000 was used for transcriptome sequencing, and real-time polymerase chain reaction (PCR) used to detect complement factors II (C2), III (C3), and V (C5); profibrinolysin (PLG); and coagulation factor II (F2) expression. A total of 2,722,223 reads were detected in the control group, and 2,751,111 in the infected group. Among 11,023 unigenes obtained after transcriptome assembly, 10,021 unigenes were significantly differentially expressed. Gene ontology and KEGG analysis, a collection of databases dealing with genomes and biological pathways, were performed to classify unigenes into functional categories, to understand gene function and identify regulatory pathways. Real-time PCR analysis showed that C2, C3, C5, PLG, and F2 expression levels were down-regulated, confirming results of pathway-enrichment analysis. This is the first application of highthroughput sequencing technology to investigate the in vivo effects of GCRV, on genes and pathways involved in the immune response to infection in grass carp.

Summary Gut microbiota could facilitate host to defense diseases, but fish–microbiota interactions during viral infection and the underlying mechanism are poorly understood. We examined interactions and responses of gut microbiota to grass carp reovirus (GCRV) infection in Ctenopharyngodon idellus, which is the most important aquaculture fish worldwide. We found that GCRV infection group with serious haemorrhagic symptoms (G7s) showed considerably different gut microbiota, especially with an abnormally high abundance of gram‐negative anaerobic Cetobacterium somerae. It also showed the lowest (p < 0.05) alpha‐diversity but with much higher ecological process of homogenizing dispersal (28.8%), confirming a dysbiosis of the gut microbiota after viral infection. Interestingly, signaling pathways of NOD‐like receptors (NLRs), toll‐like receptors (TLRs), and lipopolysaccharide (LPS) stimulation genes were significantly (q‐value < 0.01) enriched in G7s, which also significantly (p < 0.01) correlated with the core gut microbial genera of Cetobacterium and Acinetobacter. The results suggested that an expansion of C. somerae initiated by GCRV could aggravate host inflammatory reactions through the LPS‐related NLRs and TLRs pathways. This study advances our understanding of the interplay between fish immunity and gut microbiota challenged by viruses; it also sheds new insights for ecological defense of fish diseases with the help of gut microbiota.

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An 8‐week feeding experiment was aimed to investigate the effect of dietary tea polyphenols (TP) on growth, immunity and lipid metabolism in juvenile black carp Mylopharyngodon piceus (initial weight 5.90 ± 0.03 g). Tea polyphenols were added at different levels (0, 25, 50, 100 and 500 mg/kg; TP0, TP25, TP50, TP100 and TP500). The results are as follows: the highest specific growth rate (SGR) and condition factor (CF) and activity of trypsin (TRS) of intestine in TP50, but SGR and activities of lipase (LPS)and TRS of intestine and content of whole body crude protein in TP500 were remarkably lower than TP0. Compared with TP0, content of serum superoxide dismutase (SOD) and glutamic oxalacetic transaminase (GOT) remarkably increased (p < .05), but contents of glutathione (GSH), glutathione peroxidase (GSH‐Pox), malondialdehyde (MDA), triglyceride (TG) and low‐density lipoprotein cholesterol (LDL‐C) were significantly decreased (p < .05), content of cortisol was remarkably lower in TP50 and TP100 (p < .05), expression of growth hormone (GH) and melanocortin 4 receptor (MC4R) in liver and GH in muscle were remarkably up‐regulated in TP50, but expression of apolipoprotein A‐1 (ApoA1), GH and MC4R of intestine, ApoA1 of liver and MC4R of muscle in TP500 were remarkably down‐regulated, contents of complement 3 (C3), complement 4 (C4), high‐density lipoprotein cholesterol (HDL‐C) and LDL‐C were significantly reduced in TP500 (p < .05). In conclusion, TP could improve growth performance and oxidative capacity on juvenile black carp, and its optimal dosage was 50 mg/kg.

Heteropoda venatoria in the family Sparassidae is highly valued in pantropical countries because the species feed on domestic insect pests. Unlike most other species of Araneomorphae, H. venatoria uses the great speed and strong chelicerae (mouthparts) with toxin glands to capture the insects instead of its web. Therefore, H. venatoria provides unique opportunities for venom evolution research. The venom of H. venatoria was explored by matrix-assisted laser desorption/ionization tandem time-of-flight and analyzing expressed sequence tags. The 154 sequences coding cysteine-rich peptides (CRPs) revealed 24 families based on the phylogenetic analyses of precursors and cysteine frameworks in the putative mature regions. Intriguingly, four kinds of motifs are first described in spider venom. Furthermore, combining the diverse CRPs of H. venatoria with previous spider venom peptidomics data, the structures of precursors and the patterns of cysteine frameworks were analyzed. This work revealed the dynamic evolutionary trends of venom CRPs in H. venatoria: the precursor has evolved an extended mature peptide with more cysteines, and a diminished or even vanished propeptides between the signal and mature peptides; and the CRPs evolved by multiple duplications of an ancestral ICK gene as well as recruitments of non-toxin genes.