The sequence and de novo assembly of Oxygymnocypris stewartii genome.

Animal genomes in the Qinghai-Tibetan Plateau provide valuable resources for scientists to understand the molecular mechanism of environmental adaptation. Tibetan fish species play essential roles in the local ecology; however, the genomic information for native fishes was still insufficient. Oxygymnocypris stewartii, belonging to Oxygymnocypris genus, Schizothoracinae subfamily, is a native fish in the Tibetan plateau living within the elevation from roughly 3,000 m to 4,200 m. In this report, PacBio and Illumina sequencing platform were used to generate ~385.3 Gb genomic sequencing data. A genome of about 1,849.2 Mb was obtained with a contig N50 length of 257.1 kb. More than 44.5% of the genome were identified as repetitive elements, and 46,400 protein-coding genes were annotated in the genome. The assembled genome can be used as a reference for future population genetic studies of O. stewartii and will improve our understanding of high altitude adaptation of fishes in the Qinghai-Tibetan Plateau.

[Effect of locomotion and feeding on metabolic mode of juvenile lenok, Brachymystax lenok (Pallas) under different water temperatures].

To investigate the effect of locomotion and feeding on the metabolic mode of juvenile lenok, Brachymystax lenok (Pallas) under different water temperatures, the pre-exercise oxygen consumption rate (MO2p), active oxygen consumption rate (MO2a), metabolic scope (MS), critical swimming speed (Uc) and swimming metabolic rate of both fasting and fed fish were measured at five temperature levels (4 degrees C, 8 degrees C, 12 degrees C, 16 degrees C and 20 degrees C) and ten flow velocities with saturated dissolved oxygen (> 8.0 mg x L(-1)). The results showed that the MO2p and MO2a of the feeding group were significantly higher (P < 0.05) than the fasting group under different temperatures, and the increases in MO2p and MO2a at 4 degrees C, 8 degrees C, 12 degrees C, 16 degrees C and 20 degrees C were 15%, 47%, 30%, 43% and 8%, and 12%, 23%, 21%, 36% and 7%, respectively. No significant differences were observed for Uc and MS between the fasting and the feeding groups (P > 0.05), but the MS showed a trend of decline with increase in water temperature. Swimming metabolic rate of fish was increased with increasing the flow velocity, and further increase of flow velocity resulted in a decline in swimming metabolic rate, and the swimming metabolic rate of the feeding group was significantly higher than that of the fasting group (P < 0.05). The metabolic rate increased with increasing the swimming speed up to 70% Uc, and then decreased with increasing the swimming speed up to Uc. It was concluded that, under certain temperature, the maximum metabolic rate was induced by exercise and feeding; the metabolic rate exhibited the additive metabolic mode before increasing to the maximum and thereafter, the metabolic rate induced by feeding reduced with decreasing the swimming metabolic rate, exhibiting the locomotion prioritized mode.