Gangchun Xu

Molecular characterization and differential expression of the myostatin gene in Coilia nasus

Estuarine tapertail anchovy (Coilia nasus, junior synonym C. ectenes) is a widely distributed and commercially important aquaculture species, although its growth in aquaculture settings is so slow as to pose a serious practical problem. In order to understand the molecular mechanisms of growth, we cloned the myostatin gene in C. nasus (CnMSTN) by homologous cloning methods. Its full-length cDNA is 2252 bp, with a 1125-bp open reading frame (ORF) that encodes a 374-amino acid protein. The CnMSTN protein is predicted to contain domains typical of MSTN, including a TGFb-propeptide domain and a TGFB domain. Gene expression patterns were detected by RT-qPCR. CnMSTN is expressed strongly in the muscle and brain, and comparatively lower in the gills, liver, spleen, intestine, trunk kidney and head kidney. The effects of stress on the muscle and brain MSTN levels were evaluated by RT-qPCR. CnMSTN in the muscle was positively regulated by loading and transport stress, but brain CnMSTN expression was not affected. We found NaCl could reduce the death rate caused by loading and transporting stress, and in this group, CnMSTN mRNA expression in the muscle revealed increased, but decreased in the brain. Further, in the fasting experiment, the CnMSTN mRNA revealed decrease in the muscle, on the contrary, it showed increase in the brain. Selection upon variants of the MSTN gene has shown great potential in breeding work for mammals, and our results provide the basic knowledge for breeding of C. nasus.

In-depth transcriptome analysis of Coilia ectenes, an important fish resource in the Yangtze River: de novo assembly, gene annotation.

Coilia ectenes is an important teleost species in the Yangtze River and a model organism that can be used to study the protection of fish resources. In this report, we performed de novo transcriptome sequencing of ten cDNA libraries from the brain, gill, heart, intestine, kidney, liver, muscle, stomach, ovary, and testis tissues. A total of 352 million raw reads of 100 base pairs were generated, and 130,113 transcripts, corresponding to 65,350 non-redundant transcripts, with a mean length of 1520 bp, were assembled. BLASTx-based gene annotation (E-value<1 × 10(-5)) allowed the identification of 73,900 transcripts against at least one of four databases, including the NCBI non-redundant database, the GO database, the COG database, and the KEGG database. Our study provides a valuable resource for C. ectenes genomic and transcriptomic data that will facilitate future functional studies of C. ectenes.

Complete mitochondrial genome of Caridina nilotica gracilipes

Abstract In this study, we sequenced the complete mitochondrial genome of Caridina nilotica gracilipes. This mitochondrial genome, consisting of 15,550 base pairs, encoded 13 protein-coding genes, 2 ribosomal RNAs, 22 transfer RNAs, and a non-coding control region as those found in other Decapoda, with the gene synteny identical to that of typical invertebrates. Control region (D-Loop), of 673 bp in length, is located between 12S rRNA and tRNAIle. The overall base composition of the heavy strand shows T 30.4%, C 22.0%, A 33.0% and G 14.6%, with an AT bias of 63.4%.

Differences in muscle cellularity and flesh quality between wild and farmed Coilia nasus (Engraulidae).

BACKGROUND Populations of Coilia nasus, an anadromous fish, have declined dramatically in the Yangtze River estuary and its associated lakes owing to excessive fishing and changes in aquatic ecology. Recently, the success of artificial breeding programmes and advanced methods of propagation have allowed great increases in production of this species. Thus, to gain a better understanding of the flesh quality of C. nasus, muscle cellularity and quality parameters of the flesh were studied in wild and farmed specimens. RESULTS Muscle cellularity was different between wild and farmed fish. Muscle fibre density was significantly higher in farmed specimens, while muscle fibre diameter was higher in wild specimens. Farmed fish had higher moisture, hydroxyproline and collagen contents and a lower fat content compared with wild fish. No significant differences in textural parameters were found between the two groups. Saturated (SFA), polyunsaturated (PUFA) and total n-6 fatty acid contents were significantly higher in farmed fish, but monounsaturated fatty acid (MUPA) content was higher in wild fish. CONCLUSION The variation in the studied parameters determined significant differences in the flesh quality of wild and farmed C. nasus. Depending on muscle cellularity and fatty acid composition, farmed fish could be more suitable for human consumption than wild fish.

Monogonont Rotifer, Brachionus calyciflorus, Possesses Exceptionally Large, Fragmented Mitogenome

In contrast to the highly conserved mitogenomic structure and organisation in most animals (including rotifers), the two previously sequenced monogonont rotifer mitogenomes were fragmented into two chromosomes similar in size, each of which possessed one major non-coding region (mNCR) of about 4–5 Kbp. To further explore this phenomenon, we have sequenced and analysed the mitogenome of one of the most studied monogonont rotifers, Brachionus calyciflorus. It is also composed of two circular chromosomes, but the chromosome-I is extremely large (27 535 bp; 3 mNCRs), whereas the chromosome-II is relatively small (9 833 bp; 1 mNCR). With the total size of 37 368 bp, it is one of the largest metazoan mitogenomes ever reported. In comparison to other monogononts, gene distribution between the two chromosomes and gene order are different and the number of mNCRs is doubled. Atp8 was not found (common in rotifers), and Cytb was present in two copies (the first report in rotifers). A high number (99) of SNPs indicates fast evolution of the Cytb-1 copy. The four mNCRs (5.3–5.5 Kb) were relatively similar. Publication of this sequence shall contribute to the understanding of the evolutionary history of the unique mitogenomic organisation in this group of rotifers.

Complete mitochondrial genome of Paracanthobrama guichenoti

Abstract In this study, we sequenced the complete mitochondrial genome of Paracanthobrama guichenoti. This mitochondrial genome, consisting of 16,607 base pairs, encoded 13 protein-coding genes, 2 ribosomal RNAs, 22 transfer RNAs, and a non-coding control region as those found in other vertebrates, with the gene synteny identical to that of typical vertebrates. Control region (D-Loop), of 932 bp in length, is located between tRNAPhe and tRNALeu. The overall base composition of the heavy strand shows T 28.4%, C 24.6%, A 31.2% and G 15.7%, with an AT bias of 59.6%.

Spermatozoal ultrastructure and the main biological characteristics of Paracanthobrama guichenoti

Ultrastructure of spermatozoon was observed by transmission and scanning electron microscope in Paracanthobrama guichenoti. The results showed that the sperm of Paracanthobrama guichenoti consisted of a head, a midpiece and a tail. The head was ovoid in shape, of which the main structure was nucleus. It had no acrosome and at its caudal end the nucleus had an implantation fossa within 1/2 depth of the chromatin. The nucleus consisted of electron dense chromatin materials and contained irregularly netlike gap. The midpiece consisted of the centriolar complex and the sleeve. The sleve, which contained a high number of mitochondria and vesicles, was connected to the posterior end of the nucleus. The main structure of the tail was axoneme, which was slim and long. The structure of the tail was of the typical “9+2” mode1. At the proximal end of the tail there were many vesicles outside the axoneme. The distal end of the tail, however, did not contain any vesicles.