Geographical region traceability of wild topmouth culter (Culter alburnus) from Xingkai Lake based on muscle quality and aroma profiles.

The wild topmouth culter (Culter alburnus) from Xingkai Lake (XKL) is highly regarded for its delicious taste and unique flavor. In this study, based on muscle quality and aroma analysis, we first differentiated the XKL population from three wild populations in Heilongjiang Province and one artificially cultured population (from Xingkai Lake). Compared with the other populations, the XKL population has a significantly higher crude protein content, essential amino acid content, delicious amino acid content, and n-3/n-6 PUFA ratio. Additionally, it exhibits superior hardness, elasticity, chewiness, recoverability, and viscosity. E-nose detection analysis revealed that W1S, W2S, and W3S were the potential sensors contributing the most to the differences among the five populations. HS-SPME-GC-MS and multivariate regression analysis showed that 21 volatile flavor compounds were identified as key markers for geographical identification of the Xingkai Lake region. These findings will provide guidance for the geographical traceability and identification of the XKL population.

Ammonia Toxicity in the Bighead Carp (Aristichthys nobilis): Hematology, Antioxidation, Immunity, Inflammation and Stress.

Ammonia is one of the main environmental pollutants that affect the survival and growth of fish. The toxic effects on blood biochemistry, oxidative stress, immunity, and stress response of bighead carp (Aristichthys nobilis) under ammonia exposure were studied. Bighead carp were exposed to total ammonia nitrogen (TAN) concentrations of 0 mg/L, 3.955 mg/L, 7.91 mg/L, 11.865 mg/L, and 15.82 mg/L for 96 h. The results showed that ammonia exposure significantly reduced hemoglobin, hematocrit, red blood cell, white blood cell count, and platelet count and significantly increased the plasma calcium level of carp. Serum total protein, albumin, glucose, aspartate aminotransferase, and alanine aminotransferase changed significantly after ammonia exposure. Ammonia exposure can induce intracellular reactive oxygen species (ROS), and the gene expression of antioxidant enzymes (Mn-SOD, CAT, and GPx) increases at the initial stage of ammonia exposure, while MDA accumulates and antioxidant enzyme activity decreases after ammonia stress. Ammonia poisoning changes the gene expression of inflammatory cytokines; promotes the gene expression of inflammatory cytokines TNF-α, IL-6, IL-12, and IL-1ß; and inhibits IL-10. Furthermore, ammonia exposure led to increases in stress indexes such as cortisol, blood glucose, adrenaline, and T3, and increases in heat shock protein 70 and heat shock protein 90 content and gene expression. Ammonia exposure caused oxidative stress, immunosuppression, inflammation, and a stress reaction in bighead carp.

Screening and fermentation medium optimization of a strain favorable to Rice-fish Coculture.

Rice-fish coculture (RF) is a small ecosystem in which microorganisms are widely distributed in the fish, water environment, soil, and plants. In order to study the positive effects of microorganisms on common carp and rice in the RF ecosystem, a total of 18 strains with growth-promoting ability were screened from common carp (Cyprinus carpio) gut contents, among which three strains had the ability to produce both DDP-IV inhibitors and IAA. The strain with the strongest combined ability, FYN-22, was identified physiologically, biochemically, and by 16S rRNA, and it was initially identified as Bacillus licheniformis. As the number of metabolites secreted by the strain under natural conditions is not sufficient for production, the FYN-22 fermentation medium formulation was optimized by means of one-factor-at-a-time (OFAT) experiments and response surface methodology (RSM). The results showed that, under the conditions of a soluble starch concentration of 10.961 g/l, yeast concentration of 2.366 g/l, NH4Cl concentration of 1.881 g/l, and FeCl3 concentration of 0.850 g/l, the actual measured number of FYN-22 spores in the fermentation broth was 1.913 × 109 CFU/ml, which was 2.575-fold improvement over the pre-optimization value. The optimized fermentation solution was used for the immersion operation of rice seeds, and, after 14 days of incubation in hydroponic boxes, the FYN-22 strain was found to have a highly significant enhancement of 48.31% (p < 0.01) on the above-ground part of rice, and different degrees of effect on root length, fresh weight, and dry weight (16.73, 17.80, and 21.97%, respectively; p < 0.05). This study may provide new insights into the fermentation process of Bacillus licheniformis FYN-22 and its further utilization in RF systems.

Complete mitochondrial genome of Coregonus cluncaformis.

The complete mitochondrial genome of Coregonus cluncaformis was determined in this study. The mitogenome is 16 736 bp in length and contains 1D-loop region, 2 ribosomal RNA genes, 22 transfer RNA genes, and 13 protein-coding genes. The overall base composition of the heavy strand is 26.79% for A, 29.49% for C, 18.07% for G and 25.66% for T, The percentage of G + C content is 47.56%. This is the first time of the mitochondrial genome sequencing for C. cluncaformis in this study.

Complete mitochondrial genome of Coregonus usssruensis Berg.

The complete mitochondrial genome of Coregonus usssruens is was determined in this study. The mitogenome is 16,738 bp in length and contains 1D-loop region, 2 ribosomal RNA genes, 22 transfer RNA genes, and 13 protein-coding genes. The overall base composition of the heavy strand is 26.79% for A, 29.45% for C, 18.10% for G and 25.66% for T. The percentage of G+C content is 47.55%. This is the first time of the mitochondrial genome sequencing for C. usssruensis.

Mitochondrial DNA genome sequence of Ili marinka (Schizothorax pseudoaksaiensis).

Ili marinka (Schizothorax pseudoaksaiensis) belongs to the family Cyprinidae, which is found only in Ili River in the Xinjiang Uygur Autonomous Region. In this study, we reported the complete sequence of mitochondrial genome of S. pseudoaksaiensis. The genome is 16,586 bp in length and consists of 13 protein-coding genes, 22 tRNA genes, 2 ribosomal RNA genes, and the non-coding control regions (D-loop). The complete mitochondrial genome base composition is 29.80% for A, 17.85% for G, 25.31% for T, and 27.04% for C, with a slight A+T bias of 55.11%. The mitochondrial genome can contribute to the studies on genetic diversity and conservation of S. pseudoaksaiensis.

Complete mitochondrial genome of Coregonus peled.

The complete mitochondrial genome of Coregonus peled is determined in this study. The mitogenome is 16,736 bp in length and contains 1D-loop region, 2 ribosomal RNA genes, 22 transfer RNA genes and 13 protein-coding genes. The overall base composition of the heavy strand is 26.76% for A, 29.45% for C, 18.10% for G and 25.67% for T. The percentage of G + C content is 47.55 %. This is the first time of the mitochondrial genome sequencing for Coregonus peled.

Complete mitochondrial genome of Coregonus chadary Dybowski.

The complete mitochondrial genome of Coregonus chadary Dybowski was determined in this study. The mitogenome is 16,739bp in length and contains 1D-loop region, 2 ribosomal RNA genes, 22 transfer RNA genes and 13 protein-coding genes. The overall base composition of the heavy strand is 26.82% for A, 29.38% for C, 18.13% for G and 25.68% for T. The percentage of G + C content is 47.51%. This study for the first time presents the mitochondrial genome sequencing for Coregonus chadary Dybowski.

Gonadal transcriptomic analysis of yellow catfish (Pelteobagrus fulvidraco): identification of sex-related genes and genetic markers.

Yellow catfish (Pelteobagrus fulvidraco) has been recognized as a vital freshwater aquaculture species in East and Southeast Asia. In addition to its commercial interest, it is also attracted much attention because of its value in studying sex-determination mechanisms. A comprehensive gonadal transcriptome analysis is believed to provide a resource for genome annotation, candidate gene identification, and molecular marker development. Herein, we performed a de novo assembly of yellow catfish gonad transcriptome by high-throughput Illumina sequencing. A total of 82,123 contigs were obtained, ranging from 351 to 21,268 bp, and N50 of 2,329 bp. Unigenes of 21,869 in total were identified. Of these, 229 and 1,188 genes were found to be specifically expressed in XY gonad tissue for 1 yr and 2 yr old yellow catfish, respectively; correspondingly, 51 and 40 genes were identified in XX gonad tissue at those two stages. Gene ontology and KEGG analysis were conducted and classified all contigs into different categories. A large number of unigenes involved in sex determination were identified, as well as microsatellites and SNP variants. The expression patterns of sex-related genes were then validated by quantitative real-time PCR (qRT-PCR) suggesting the high reliability of RNA-Seq results. In this study, the transcriptome of yellow catfish gonad was first sequenced, assembled, and characterized; it provides a valuable genomic resource for better understanding of yellow catfish sex determination as well as development of molecular markers, thereby assisting in the production of monosex yellow catfish for aquaculture.