Fu Lv

Effects of astaxanthin and emodin on the growth, stress resistance and disease resistance of yellow catfish (Pelteobagrus fulvidraco).

Yellow catfish (Pelteobagrus fulvidraco) has become a commercially important fish species in China and eastern Asia. High-density aquaculture has led to congestion and excessive stress and contributed to bacterial infection outbreaks that have caused high mortality. We investigated the effects of dietary supplementation with astaxanthin and emodin alone and in combination on the growth and stress resistance of yellow catfish. After 60 days of feeding, each group of fish (control, astaxanthin, emodin, and astaxanthin plus emodin (combination) groups) was exposed to acute crowding stress for 24 h, and a subsample of fish from the four groups was challenged with the bacterial septicemia pathogen Proteus mirabilis after the end of the crowding stress experiment. Compared with the control, the astaxanthin and emodin groups showed increases in serum total protein (TP), hepatic superoxide dismutase (SOD) activity and hepatic heat shock proteins 70 (HSP70) mRNA levels at 12 and 24 h after the initiation of crowding stress. The combination group exhibited increases in alanine aminotransferase (ALT) activity, aspartate aminotransferase (AST) activity, serum TP, hepatic SOD activity and hepatic HSP70 mRNA levels within 24 h after the initiation of crowding stress. However, decreases relative to the control were observed in the serum cortisol and glucose contents in the three treatment groups at 12 and 24 h after the initiation of crowding stress, in ALT and AST activity in the astaxanthin and emodin group at 24 h after the initiation of crowding stress, and in the serum lysozyme activity, serum alkaline phosphatase (ALP) activity, and hepatic catalase (CAT) and malondialdehyde (MDA) activity in the combination group at 24 h after the initiation of crowding stress. Additionally, the cumulative mortality after P. mirabilis infection was lower in all three treatment groups (57.00%-70.33%) than in the control (77.67%). Dietary supplementation with astaxanthin and emodin decreased the specific growth rate (SGR) and weight gain (WG) of healthy yellow catfish, although significant differences in mortality were not observed. These results indicate that dietary supplementation with 80 mg/kg astaxanthin and 150 mg/kg emodin can improve the anti-oxidative capabilities, hepatic HSP70 levels, and resistance to acute crowding stress of yellow catfish. Finally, an appropriate strategy for enhance yellow catfish stress resistance and disease resistance is proposed.

Effects of various feeding patterns of Bacillus coagulans on growth performance, antioxidant response and Nrf2-Keap1 signaling pathway in juvenile gibel carp (Carassius auratus gibelio)

ABSTRACT The present study was conducted to evaluate the effects of various Bacillus coagulans feeding patterns on growth, antioxidant parameter and Nrf2 pathway in juvenile gibel carp. The similar size of gibel carp (initial weight: 14.33 ± 0.15 g) were subjected to three levels of B. coagulans supplementation (0, 500, and 1000 mg/kg) and two feeding modes (supplementing B. coagulans continuously or for two days of B. coagulans after 5 days of a basal diet) according to a 3 × 2 factorial design. The fish that were continuously fed 500 mg/kg B. coagulans (P2) and those fed the first basal diet for 5 days followed by 500 mg/kg or 1000 mg/kg B.coagulans for 2 days (P4 or P5) showed higher weight gain rate and specific growth rate than the other groups. Blood respiratory burst (RB), myeloperoxidase (MPO), and anti‐superoxide anion free radical (AFASER) activities in the P4 group were higher than those of the control. White blood cell count (WBC), RB activity, MPO activity, and glutathione (GSH) content in the P5 group were also higher than those of the control. A similar higher trend was observed in the gene expressions of NADPH oxidase 2 (NOX2), NFE2‐related factor (Nrf2), Kelch‐like‐ECH‐associated protein(Keap1) in the P4 and NOX2, NRF2, CNC homolog 1 (Bach1), peroxiredoxin 2 (Prx2) in the P5 group compared with the control. Additionally, we observed a significantly lower level of plasma aspartate aminotransferase (AST), lower activity of alanine aminotransferase (ALT), a higher level of MPO, higher GPX activity, and increased NRF2 and Prx2 expression were all observed in the P2 treatment group compared with the control. Furthermore, the malondialdehyde (MDA) content in the P2, P3, and P4 groups was lower than that of the control. These results indicate that a diet supplemented with appropriate levels of B.coagulans could improve the growth, immune response, and antioxidant capability of gibel carp. We concluded that the pattern of two days of 500 or 1000 mg/kg B. coagulans after 5 days of a basal diet was recommended for gibel carp. HIGHLIGHTSThe feeding strategies of Bacillus coagulans impacted on the growth performance of gibel carp.Dietary Bacillus coagulans activated Nrf2‐Keap1 pathway of antioxidant gene regulation.The feeding strategies of Bacillus coagulans prevented the damage of oxidative stress.

Antioxidant enzymes responses of polychaete Perinereis aibuhitensis following chronic exposure to 17β-estradiol

Abstract The occurrence of 17β-estradiol (E2) in the aquatic environment can lead to damage to the reproductive system, along with other adverse effects including oxidative stress, in aquatic organisms. In the present study, Perinereis aibuhitensis were treated with E2 at 0.1, 1, 10, 100 and 1000 μg/L for 205 d, after which the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST), and the concentrations of glutathione antioxidant biomarker responses were studied. Weight gain and specific growth rate of P. aibuhitensis were not significantly affected by E2 treatment. Although no significant differences in mortality were observed, the group receiving the highest dose of E2 (1000 μg/L) experienced the highest rate of mortality. Treatment with E2 enhanced the levels of total glutathione (T-GSH), but levels of glutathione reduced (GSH) were significantly decreased by 17.02, 20.55, 23.45, 31.91 and 56.08%, with a concomitant increase in the levels of glutathione disulphide (GSSG) by 148.58, 213.05, 232.62, 294.63 and 306.45%, at 0.1, 1, 10, 100 and 1000 μg/L E2, respectively. The redox ratio of GSH/GSSG was significantly decreased (p < 0.01). The results of this study suggest that long-term exposure of P. aibuhitensis to E2 may inhibit antioxidant enzyme activities, thereby reducing the capacity of its detoxification system.

De Novo Assembly and Characterization of Transcriptome in Somatic Muscles of the Polychaete Perinereis aibuhitensis

ABSTRACT Lv, F.; Wang, T.; Liu, F.; Yebing, Y.; Qiao, G.; Wang, Z., and Qi, Z., 2017. De novo assembly and characterization of transcriptome in somatic muscles of the polychaete Perinereis aibuhitensis. The polychaete Perinereis aibuhitensis is a common species distributed throughout coastal and estuarine regions with growing importance in aquaculture. However, the knowledge of molecular mechanism of physiology and pathology of this polychaete has been limited. In this study, the transcriptome of somatic muscles of P. aibuhitensis was sequenced using the Illumina HisSeq 2000 sequencing platform. As a result, 53,204 unigenes with a length of 63,967,647 base pairs (bp) were obtained, among which 29,797, 9951, and 24,844 unigenes were matched in the nonredundant, nucleotide, and Swiss-Prot databases, respectively. Gene ontology analysis revealed that 9938 unigenes were classified into three categories: biological process, cellular component, and molecular function. In addition, 21,756 unigenes were grouped into 257 annotated pathways in the Kyoto Encyclopedia of Genes and Genomes database. More importantly, genes involved in fatty acid biosynthesis and metabolism, muscle contraction, and innate immunity of P. aibuhitensis were analyzed in detail. In addition, 4682 simple sequence repeats and 32,202 candidate single nucleotide polymorphisms were identified from the P. aibuhitensis transcriptome. These data facilitate further studies of the physiology and molecular response of P. aibuhitensis. Furthermore, these results contribute to the molecular basis for coastal research worldwide, using P. aibuhitensis as a model animal in the fields of environmental ecology, toxicology, etc.

Molecular cloning and characterization of an estrogen receptor gene in the marine polychaete Perinereis aibuhitensis

Estrogen receptors (ERs) are the primary mediators of estrogen signaling, and play crucial roles in the reproduction and development of vertebrates. The full-length cDNA of Perinereis aibuhitensis estrogen receptor (paER) was cloned and characterized for the first time. The positions of the cysteine residues and the residues around them, which constitute two zinc finger motifs and a P-box, are conserved in both vertebrates and invertebrates. A phylogenetic analysis revealed that paER is an orthologue of ER in the polychaete Platynereis dumerilii. A tissue distribution analysis of paER mRNA showed that it is expressed in various tissues, including the body wall, head, esophageal gland, esophagus, stomach, and most strongly in the intestines. Its expression was also measured in P. aibuhitensis after exposure to 17β-estradiol (E2) for 48h. The paER mRNA levels in the body wall were measured after 6, 12, 24, and 48h in E2-exposed and control animals. However, no significant differences in paER expression were observed between them at any time point. This report describes the first molecular characterization of full-length paER and its tissue-specific expression in P. aibuhitensis.