Yuanchao Zou

Effects of pathogenic bacterial challenge after acute sublethal ammonia-N exposure on heat shock protein 70 expression in Botia reevesae.

The objective of this study was to investigate the effects of pathogenic bacterial challenge after acute sublethal ammonia-N exposure on heat shock protein 70 expression in Botia reevesae. After ammonia-N exposure at a constant concentration of 7.21 ± 0.10 mg L(-1) for 96 h, B. reevesae was challenged with Aeromonas hydrophila. Quantitative PCR analysis showed predominant and significant expression of HSP70 in liver, gill, skin, spleen and kidney (P < 0.05), with significantly upregulated expression of the mRNA transcript in these tissues after sublethal ammonia-N exposure and A. hydrophila challenge. Furthermore, following A. hydrophila challenge after ammonia-N exposure, HSP70 mRNA expression was significantly upregulated in kidney and gill tissues, although its expression levels were significantly lower than those detected following A. hydrophila challenge or ammonia-N exposure individually. These results indicate that B. reevesae HSP70 is involved in resistance to pathogenic bacteria. It is hypothesized that ammonia-N results in the downregulation of HSP70 mRNA in immune organs after an A. hydrophila challenge, thus lowering their resistance to pathogenic stress.

Comparative analysis of the liver transcriptome of Pelteobagrus vachellii with an alternative feeding time

Pelteobagrus vachellii, an important freshwater fish in China, shows predominantly nocturnal behavior. To better understand the growth and molecular mechanisms underlying altered feeding times in this species, we studied the growth and liver transcriptome of P. vachellii with shifted feeding times. In this study, a 9-week growth trial was conducted on male P. vachellii (mean weight±S.E.=1.05±0.36g) with commercial feed. Two triplicate groups of fish were fed either at 0800 (day group, control) or at 2000 (night group) with the same amount of feed. After nine weeks, a significant increase in growth was observed in the night group, demonstrated by the specific growth rate (SGR). Using high-throughput RNA-seq, 70,793,844 and 67,930,610 paired-end clean reads were obtained from six cDNA libraries of P. vachellii liver, and 60,069 unigenes were assembled. Gene expression comparison revealed that 122 genes were significantly up-regulated and 59 genes were significantly down-regulated in the night group. Gene pathway and GO enrichment analyses revealed metabolic responses of genes and gene networks related to protein, lipid and carbohydrate metabolism and rhythms. This study indicates that an alternative feeding time can improve growth and create metabolic alterations in the liver of P. vachellii.

Molecular cloning, tissue distribution, and effect of fasting and refeeding on the expression of neuropeptide Y in Channa argus

Neuropeptide Y (NPY) is a 36 amino-acid amidated peptide of the pancreatic polypeptide (PP) family, which plays an important role in appetite regulation and energy expenditure in mammals. Although several teleost NPY have been identified, its roles remain unclear in fish. We herein reported on the molecular cloning, tissue distribution and the effect of fasting on the expression of NPY in Channa argus, and designated as CaNPY. It consisted of a 300 bp open reading frame predicted to encode a prepro-NPY of 99 amino acids. Sequence analysis revealed that CaNPY was highly conserved (>60%) with other vertebrate NPY. Phylogenetic analysis highly supported CaNPY was closely related to piscine NPY. In addition, except for muscle and spleen tissues, CaNPY was found to extensively expressed in all other detected tissues, with the highest level in brain. Futhermore, the CaNPY transcript was found to significantly increase after short-term and long-term food deprivation, and dramatically decrease following refeeding. These findings suggested that CaNPY might be involved in food intake regulation and it could be as a potential target locus to improve commercial production of this kind of fish.

The complete mitochondrial genome of Sarcocheilichthys davidi and its phylogeny

Abstract Sarcocheilichthys davidi is a small-size ornamental freshwater species. In the present study, the complete mitochondrial genome of S. davidi was first determined using the next-generation sequencing technology. The result showed that the circular mitogenome was 16,675 bp in length, contained 13 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and two non-coding regions: origin of light-strand replication (OL) and displacement loop locus (D-loop). In addition to ND6 and eight tRNA genes, most mitochondrial genes were encoded on the heavy strand. Furthermore, the overall base composition was 29.97% A, 26.12% T, 26.86% C, 17.04% G, respectively, and showed AT-rich feature (56.09%). Moreover, phylogenetic analysis based on the tandem 13 PCGs nucleotide sequences indicated that S. davidi had a close relationship with S. snigripinnis and S. variegatus wakiyae. The complete mitogenome sequence of S. davidi would contribute to the better understanding of molecular systematics, selection, conservation, species identification and evolution of this species.

Sequence identification and phylogenetic analysis of the mitochondrial genome of Microphysogobio kiatingensis (Cypriniformes: Cyprinidae)

Abstract Microphysogobio kiatingensis is endemic freshwater fish of China and mainly distributed in the middle and upper reaches of the Yangtze River. The complete mitogenome of M. kiatingensis was first determined by using the next-generation sequencing in present study. The circular mitogenome followed the expected pattern for vertebrates, being 16,603 bp in length. It contained 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, one displacement loop (D-loop) locus and an origin of replication on the light-strand (OL). Most of the genes are encoded on the heavy strand except ND6 and eight tRNA genes. The overall base composition was 30.78% A, 26.09% T, 26.59% C, 16.54% G, with 56.87% AT. Thirteen intergenic spacers and nine gene overlaps exist in the complete mitochondrial genome. Phylogenetic analysis based on the tandem 13 coding protein genes nucleotide sequences with two different methods (maximum likelihood and neighbour-joining analysis) indicated that M. kiatingensis was grouped in one clade with the same genus. The complete mitogenome of M. kiatingensis can provide a useful data for the further research in Gobioninae. Meanwhile, it also provides help for biological genetics and classification of species.

Identification and analysis of the complete mitochondrial genome of Acheilognathus omeiensis (Cypriniformes, Cyprinidae)

Abstract Acheilognathus omeiensis is a small-size freshwater ornamental fish. In this study, the complete mitochondrial genome sequence of A. omeiensis was first determined. This mitogenome was 16,774 bp in length and contained 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and 2 main noncoding regions. Most mitochondrial genes were encoded on the H-strand, except for ND6 and eight tRNA genes. The base composition was 28.97% A, 27.72% T, 26.02% C, and 17.29% G, with 56.69% AT, respectively. Phylogenetic tree was constructed based on the nucleotide sequence of 13 PCGs of A. omeiensis and closely related 12 species ticks to assess their phylogenic relationship and evolution. These data should be helpful for a better understanding of the mitochondrial genomic diversities and evolution in fish as well as novel genetic markers for studying population genetics and species identification.