Exposure to nanopolystyrene and phoxim at ambient concentrations causes oxidative stress and inflammation in the intestines of the Chinese mitten crab (Eriocheir sinensis).

Nanopolystyrene (NP) and phoxim (PHO) are common environmental pollutants in aquatic systems. We evaluated the toxic effects of exposure to ambient concentrations of NP and/or PHO in the intestines of the Chinese mitten crab (Eriocheir sinensis). Our study showed that histopathological changes were observed in the intestines. Specifically, NP and/or PHO exposure increased intraepithelial lymphocytes. Furthermore, NP and/or PHO exposure induced oxidative stress, as evidenced by a significant decrease in superoxide dismutase activity (SOD), peroxidase activity (POD), and total antioxidant capacity (T-AOC). Pro-inflammatory gene expression and transcriptome analysis demonstrated that NP and/or PHO exposure induced the intestinal inflammatory response. Transcriptome results showed that NP and/or PHO exposure upregulated the NF-κB signaling pathway, which is considered a key pathway in the inflammatory response. Additionally, the expression of pro-inflammatory genes significantly increased after a single exposure to NP or PHO, but it exhibited a significant decrease after the co-exposure. The downregulation of these genes in the co-exposure group likely suggested that the co-exposure mitigated intestinal inflammation response in E. sinensis. Collectively, our findings mainly showed that NP and/or PHO exposure at ambient concentrations induces oxidative stress and inflammatory response in the intestines of E. sinensis.

Toxic effects of nanopolystyrene and cadmium on the intestinal tract of the Chinese mitten crab (Eriocheir sinensis).

Nanopolystyrene (NP) and cadmium (Cd) are ubiquitous contaminants in aquatic systems. The present study aimed to investigate the toxic effects of exposure to ambient concentrations of NP and/or Cd on the intestinal tract of the Chinese mitten crab (Eriocheir sinensis). Exposure to NP and/or Cd induced oxidative stress, as evidenced by a significant increase in lipid peroxide content (LPO), total antioxidant capacity (T-AOC), and peroxidase activity (POD), and significant decreases in superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activities in E. sinensis. In addition, exposure to NP and/or Cd imbalanced the homeostasis of the intestinal microbiota, as demonstrated by the significantly increased abundance of Spiroplasma. Transcriptomic and metabolomic analyses were performed to investigate the mechanisms underlying intestinal toxicity. Our results showed that ferroptosis, ABC transporters, phosphotransferase system, apoptosis, and leukocyte transendothelial migration were disturbed after exposure to NP and/or Cd. In particular, Cd exposure affected mucin type O-glycan biosynthesis, purine metabolism, and neuroactive ligand-receptor interaction. Intriguingly, co-exposure to NP and Cd might mitigate intestinal toxicity by decreasing oxidative stress and affecting these pathways. Taken together, our study clearly demonstrates that exposure to NP and/or Cd at environmentally relevant concentrations causes intestinal toxicity in E. sinensis.

RNAi silencing of the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene inhibits vitellogenesis in Chinese mitten crab Eriocheir sinensis.

The sesquiterpenoid methyl farnesoate (MF), a de-epoxide form of insect juvenile hormone III (JH III), plays an essential role in regulating many crucial physiological processes in crustaceans including vitellogenesis and reproduction. 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is an important rate-limiting enzyme in the mevalonate pathway, which is critical for the synthesis of JH III and MF. In the present study, a full-length cDNA encoding HMGR (EsHMGR) in Eriocheir sinensis was isolated and characterised. Sequence analysis of EsHMGR revealed that it belongs to Class I HMGR family proteins with HMG-CoA-binding and NADPH-binding domains, both important for HMGR activity. In addition to its ubiquitous tissue expression, expression of EsHMGR was highly specific to the ovary, the main site of Vg synthesis. During ovarian development, EsHMGR expression in ovary displayed a stage-specific pattern, and was correlated with expression of vitellogenin (EsVg) in hepatopancreas, which suggests that EsHMGR possibly involved in vitellogenesis. To further investigate the functional role of EsHMGR in vitellogenin biosynthesis in E. sinensis, RNA interference-mediated gene silencing was carried out both in vitro and in vivo. Quantitative PCR results showed that injection of EsHMGR double-stranded RNA (dsRNA) led to a significant decrease in EsVg expression levels in ovary and hepatopancreas both in vitro and in vivo. Taken together, the results suggest that EsHMGR is involved in vitellogenin biosynthesis in female E. sinensis, which may provide a new resource for HMGR enzymes participating in reproduction in crustaceans.

Molecular evidence for farnesoic acid O-methyltransferase (FAMeT) involved in the biosynthesis of vitellogenin in the Chinese mitten crab Eriocheir sinensis.

Sesquiterpenoid methyl farnesoate (MF), a crustacean equivalent of insect juvenile hormone (JH III), has essential functions in regulating physiological processes in crustaceans, including reproduction and vitellogenesis. Farnesoic acid O-methyltransferase (FAMeT) is a key rate-limiting enzyme catalyzing the conversion of farnesoic acid (FA) to JH/MF in insects and crustaceans. In this study, a full-length cDNA of EsFAMeT from Eriocheir sinensis was isolated and characterized. The deduced EsFAMeT amino acid sequence indicated there were two conserved Methyltransf-FA domains characteristic of FAMeT family proteins. With use of sequence alignment analysis procedures, there was an indication that FAMeT proteins are highly conserved among crustaceans and FAMeT is more closely related to crustacean FAMeT than to insect FAMeT. Results from quantitative real-time PCR analysis revealed there was ubiquitous EsFAMeT in all tissues examined, with greater abundances of mRNA transcripts in the ovary. The transcription of EsFAMeT indicated there were stage-specific patterns in the hepatopancreas and ovary during ovarian development, with the greatest abundance during ovarian development Stages II and III, respectively. To investigate functions of EsFAMeT in vitellogenin biosynthesis in E. sinensis, RNA interference-mediated gene knockdown was used in vitro and in vivo. Injection of EsFAMeT dsRNA resulted in a marked decrease in EsVg (encoding vitellogenin) transcripts in the ovary and hepatopancreas both in vitro and in vivo. Results from the present study indicated EsFAMeT is involved in vitellogenin biosynthesis in the ovary and hepatopancreas of E. sinensis, providing a new resource to study modulatory effects of the FAMeT family of enzymes in crustacean reproduction.

Screening and characterisation of sex differentiation-related long non-coding RNAs in Chinese soft-shell turtle (Pelodiscus sinensis).

Long non-coding RNAs (lncRNAs) perform distinct functions in various biological processes in mammals, including sex differentiation. However, the roles of lncRNAs in other vertebrates, especially in the Chinese soft-shell turtle (Pelodiscus sinensis), remain to be clarified. In this study, we performed genome-wide analysis of the lncRNA expression profiles in gonad tissues and screened numerous sex-specific lncRNAs in the Chinese soft-shell turtle. Of the 363,310,650 clean reads obtained, 5,994 sequences were typed as lncRNAs, of which 4,463 were novel. A selection of sex-specific lncRNAs (♀ 932, ♂ 449) from female ovaries and male testis were shown to act on target genes in cis and in trans, and most were involved in gonad differentiation based on Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Furthermore, interactions among the differentially expressed lncRNA-mRNAs and protein coding genes were identified by construction of correlation networks. Overall, our systematic analysis of lncRNA expression profiles in gonad tissues revealed numerous sex-specific lncRNAs in P. sinensis. Thereby, these findings provide new insights into the function of lncRNAs in sex differentiation and highlight a group of candidate lncRNAs for future studies.

Identification of three novel B-cell epitopes of VMH protein from Vibrio mimicus by screening a phage display peptide library.

Vibrio mimicus is the causative agent of ascites disease in fish. The heat-labile hemolytic toxin designated VMH is an immunoprotective antigen of V. mimicus. However, its epitopes have not been well characterized. Here, a commercially available phage displayed 12-mer peptide library was used to screen epitopes of VMH protein using polyclonal rabbit anti-rVMH protein antibodies, and then five positive phage clones were identified by sandwich and competitive ELISA. Sequences analysis showed that the motif of DPTLL displayed on phage clone 15 and the consensus motif of SLDDDST displayed on the clone 4/11 corresponded to the residues 134-138 and 238-244 of VMH protein, respectively, and the synthetic motif peptides could also be recognized by anti-rVMH-HD antibody in peptide-ELISA. Thus, both motifs DPTLL and SLDDDST were identified as minimal linear B-cell epitopes of VMH protein. Although no similarity was found between VMH protein and the consensus motif of ADGLVPR displayed on the clone 2/6, the synthetic peptide ADGLVPR could absorb anti-rVMH-HD antibody and inhibit the antibody binding to rVMH protein in enhanced chemoluminescence Western blotting, whereas irrelevant control peptide did not affect the antibody binding with rVMH. These results revealed that the peptide ADGLVPR was a mimotope of VMH protein. Taken together, three novel B-cell epitopes of VMH protein were identified, which provide a foundation for developing epitope-based vaccine against V. mimicus infection in fish.

The complete sequence of mitochondrial genome of Sinibotia pulchra (Cypriniformes: Cobitidae).

Sinibotia pulchra (Cypriniformes: Cobitidae) is a small cyprinid fish. In this study, the complete mitochondrial genome sequence of S. pulchra is sequenced. The S. pulchra complete mitochondrial genome (GenBank accession no. KT362179) was a circular molecule of 16 568 bp in length, with 13 protein-coding genes (PCGs), 2 ribosome RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, an L-strand replication origin (OL) and a control region (D-loop). The nucleotide acid composition of the entire mitogenome was 31.69% for A, 25.63% for T, 26.94% for C and 15.74% for G, with an AT content of 57.32%. The AT content of 12S rRNA, 16S rRNA and D-loop was 50.21%, 56.86% and 66.74%, respectively.

The complete mitochondrial genome of Sinibotia robusta (Cypriniformes: Cobitidae).

The Sinibotia robusta mitochondrial genome (GenBank accession no. KP979711) was a circular molecule of 16 575 bp in length, with two rRNA genes, 13 protein-coding genes, 22 tRNA genes, an l-strand replication origin (OL), and a control region (D-loop). The nucleotide acid composition of the entire mitogenome was 31.91% for A, 26.90% for C, 15.56% for G, and 25.63% for T, with an A + T content of 57.54%. And the A + T content of 12S rRNA, 16S rRNA, and D-loop was 51.26%, 56.17%, and 67.73%, respectively.

The complete mitochondrial genome of Botia lohachata (Cypriniformes: Cobitidae).

In this study, the complete mitochondrial genome of Botia lohachata was determined (GenBank accession number KP729183). The mitochondrial genome sequence of B. lohachata was a circular molecule with 16,594 bp in length, and it contained 37 typical animal mitochondrial genes: 2 ribosomal RNA genes, 13 protein-coding genes, 22 transfer RNA genes, an L-strand replication origin (OL) and a control region (D-loop). The nucleotide acid composition of the entire mitogenome was 26.53% C, 15.63% G, 31.98% A and 25.86% T, with an AT content of 57.83%.

Complete sequence and characterization of the paradise fish Macropodus erythropterus (Perciformes: Macropodusinae) mitochondrial genome.

Macropodus erythropterus is a small well-known aquarium fish. In the present study, the complete mitochondrial DNA (mtDNA) sequences of M. erythropterus were first determined. The mtDNA of M. erythropterus (GenBank accession no. KU215670) was a circular molecule of 16 495 bp in length with two ribosome RNA (rRNA) genes, 13 protein-coding genes, 22 transfer RNA genes, an L-strand replication origin and a control region (CR). The entire mitogenome nucleotide acid was 15.71% for G, 29.66% for A, 28.37% for T and 26.26% for C with an A + T content of 58.03%. And the A + T contents of 12S rRNA, 16S rRNA and CR were 55.63%, 57.66% and 66.79%, respectively. This study provides basic molecular data for studying the conservation biology, phylogenetic and evolutionary analysis of Macropodusinae fishes.

The complete mitochondrial genome of Chinese lizard gudgeon, Saurogobio dabryi (Cypriniformes: Cyprinidae).

Saurogobio dabryi is a small-sized benthopelagic fish species in the famally Cyprinidae. In the present study, the complete mitochondrial genome of S. dabryi was determined. The complete mitochondrial genome of S. dabryi was 16,601 bp in length with the overall nucleotide base composition of A (29.66%), T (26.50%), G (16.80%) and C (27.04%), as well as an AT content of 56.16%. It contained 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, a control region and an L-strand replication origin (OL).