The Schizothoracinae fishes, endemic species in the Tibetan Plateau, are considered as ideal models for highland adaptation and speciation investigation. Despite several transcriptome studies for highland fishes have been reported before, the transcriptome information of Schizothoracinae is still lacking. To obtain comprehensive transcriptome data for Schizothoracinae, the transcriptome of a total of 183 samples from 14 representative Schizothoracinae species, were sequenced and de novo assembled. As a result, about 1,363 Gb transcriptome clean data was obtained. After the assembly, we obtain 76,602-154,860 unigenes for each species with sequence N50 length of 1,564-2,143 bp. More than half of the unigenes were functionally annotated by public databases. The Schizothoracinae fishes in this work exhibited diversified ecological distributions, phenotype characters and feeding habits; therefore, the comprehensive transcriptome data of those species provided valuable information for the environmental adaptation and speciation of Schizothoracinae in the Tibetan Plateau.

Northern snakehead, Channa argus (C. argus), is an important economic and ecological fish species. The wild population of the species was sharply declined in the last decade. A high-quality reference genome could lay a solid foundation for the genetic and conservation studies for C. argus. In this work, we report a chromosomal genome assembly with PacBio and Hi-C technology using the albino northern snakehead, a color variety of C. argus. A 644.1-Mb genome with 24 chromosomes was obtained with a contig and scaffold N50 of 11.78 and 27.8 Mb, respectively. We inferred that C. argus diverged from A. testudineus around 85.6 million years ago. 514 expanded gene families and 214 positively selected genes were identified in the C. argus genome. The chromosome-level genome provides a valuable high-quality genomic resource for population, as well as genetic and evolutionary studies for C. argus and other species in Channidae.

Several studies have demonstrated that the neuropeptide peptide YY (PYY) plays an important role in feeding in mammals and fish. However, thus far, the feeding regulation function of PYY in Schizothorax davidi has not been well understood. Here, we identified the full-length cDNA sequence of PYY in S. davidi for the first time. S. davidi PYY contains 803 bp nucleotides including a 328 bp 3' untranslated region (UTR), a 181 bp 5' UTR, and a 294 bp open reading frame encoding a peptide of 97 amino acids. S. davidi PYY expression was observed in almost all tissues, with the highest expression detected in the hypothalamus. PYY mRNA expression in the hypothalamus was significantly elevated after a meal (P < 0.01), and significantly decreased after fasting (P < 0.01). PYY expression levels were increased sharply following refeeding after 9 days (P < 0.01), suggesting that it might function as a satiety factor in S. davidi.

Fermented juice was prepared with byproducts (pulp and rind) of seed watermelon (Citrullus lanatus sp. vulgaris var. megalaspermus) for the first time, and its radical scavenging capacity and aroma were compared with those of the corresponding unfermented juice. The 2,2-diphenyl-1-picryhydrazyl and hydroxyl radical scavenging capacities of the fermented juice were significantly stronger than those of the unfermented juice. The oxygen radical scavenging capacity of the fermented juice was 60 µM trolox equivalent/mL, which was 7.14% higher than that of the unfermented juice. Gas chromatography-mass spectrometer analysis showed a total of 26 and 29 volatiles in unfermented juice and fermented juice, respectively. The content of typical watermelon aroma, including 1-nonanol, 3,6-nonadien-1-ol, nonanal, trans-2-nonenal, and trans,cis-2,6-nonadienal, was reduced from 92.08 mg/L in the unfermented juice to 26.41 mg/L in the fermented juice. Furthermore, isoamylol, ethyl octanoate, ethyl acetate, and ethyl laurate contributed a typical grape-wine bouquet to the fermented juice. Sensory evaluation further confirmed the attractive appearance and watermelon aroma of the fermented juice. Therefore, the fermented seed-watermelon juice showed a strong radical scavenging capacity and presented the typical watermelon aroma with a grape-wine bouquet.

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