The ya-fish, Schizothorax prenanti, is a well-known commercial cold-water fish species with the hexaploid karyotype distributed in the upper reaches of the Yangtze River and its tributaries on the western Sichuan Plateau in China. The complete mitogenome of S. prenanti is 16,587 bp in length, containing 37 genes of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a control region (D-loop). The gene nucleotide composition of S. prenanti is 29.6% A, 25.4% T, 27.1% C and 17.9% G, with a slight AT bias of 55.0%. The complete mitogenome sequence of S. prenanti could provide useful data for further studies on genetic structure and diversity, as well as the artificial cultivation and breeding of S. prenanti.

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Releasing juvenile fish into the resource-depleted waters, is regarded as an effective way to restore fishery resources. However, during this stage, released fish are most vulnerable to long-term food deprivation due to environmental changes and low adaptability. Therefore, research regarding the energy regulation of fish under starvation stress is crucial to the optimization of release strategies. In this study, we performed a comparative transcriptome analysis of the liver of Onychosoma sima subjected to starvation for 14 days. The results showed that, under long-term starvation, the liver regulated glucose homeostasis by activating the gluconeogenesis pathway. Meanwhile, the fatty acid metabolism pathway was activated to supply acetyl-coA to the TCA cycle pathway, thus increasing mitochondrial ATP production and maintaining the balance of energy metabolism. Nevertheless, the activation of energy metabolism could not completely compensate for the role of exogenous nutrients, as evidenced by the downregulation of many genes involved in antioxidant defenses (e.g., cat, gpx3, mgst1, and mgst2) and immune response (e.g., c3, cd22, trnfrsf14, and a2ml). The consequence is multiple metabolic disorder, and the body resistance weakened. In summary, our data reveal the effects of long-term starvation on the energy metabolism and defensive regulation of released fish, and these findings will provide a new theoretical basis for the optimization of artificial release.

Gymnodiptychus pachycheilus, an endangered cold-water fish belonging to the specialized schizothoracins, is distributed in plateau lakes and the upper reaches of the Yellow and Yangtze Rivers on the northeastern Qinghai-Tibet Plateau in China. In this study, we determined the complete mitogenome sequence of G. pachycheilus. Its complete mitochondrial genome is 16,675 bp in size, and includes 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and 1 control region, which has identical genomic organization and structure to other vertebrates, with the exception of 86 bp non-coding region between tRNA(Thr) and tRNA(Pro). This new complete mitogenome could provide useful data for further studies on stock evaluation and conservation genetics of this species.