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[Objective] The present paper aimed to study the genetic diversity and population structure of different geographical populations of Triplophysa lixianensi in Lixian county, and to further utilize the genetic germplasm resources of T. lixianensi in Lixian county so as to protect its wild population, the population structure of T. lixianensi in the Yangtze River Basin was investigated in the present study. [ Method] In the study, length composition, body weight composition, length-weight relationships and genetic structure variation of 117 T. lixianensis in four regions of Dadu River were analyzed, and the genetic diversity analysis was performed using D-loop control region of mitochondrial DNA. [Result] The regression equation of body weight and body length was y = 0. 0123x2.9734. The b value was 2. 9734 which was close to 3, indicating that the current growth state was acceptable. A total of 32 variable sites and 28 haplotypes were identified in 878 base pairs of 117 individuals. There was no shared haplotypes among the individuals from four regions. The haplotype diversity of four populations ranged from 0. 637 to 0. 921, and the nucleotide polymorphisms of four populations ranged from 0. 000 91 to 0. 005 70. There was no genetic differentiation between Jinchuan population and Danba population, Luding population and Shimen population, but there was significant genetic differentiation between Luding population and Jinchuan population or Danba population, and between Shimian population and Jinchuan population or Danba population. By constructing the NJ tree, we found that 117 individuals of T. lixianensis formed two independent branches in the evolutionary tree, which was consistent with the genetic distance results of each geographical population. [Conclusion] We suggest that Jinchuan and Danba populations of Dadu River should be managed and protected as a whole protection unit, and that Shimian and Luding populations should also be managed and protected as a whole, while Jinchuan and Danba populations, Shimian and Luding populations should be managed and protected separately. [ABSTRACT FROM AUTHOR]

【Objective】 Glucocorticoid receptor (GR) was involved in various biological processes such as osmoregulation, stress and immune modulation in diverse organisms. Therefore, the analysis of GR expression characteristics was conductive to revealing its function in the anti-stress response of fish.【Method】 In the present study, the cDNA of Acipenser dabryanus GR was cloned from the unigene database by transcriptome sequencing of A. dabryanus. The tissue distribution and expression level during starvation stress were further analyzed. 【Result】 The open reading frame of GR was 2316 bp, encoding 771 amino acids, including the conserved zinc finger domain, ligand binding domain of hormone receptors, and the fish specific 9-aa insertion sequence WRARQNMDG. Results showed that GR was ubiquitously expressed in all tested tissues, and was highly expressed in immune-related tissues such as spleen, liver and gill. Relatively high expression levels of GR were also found in brain and heart. Under starvation conditon, the expression level of hepatic GR increased during fasting period and was significantly higher than that of the control group in 7 days and 14 days post starvation. The peak expression of intestinal GR on day 7 of starvation was significantly higher than that on day 0（P<0.05）. After refeeding, the expression level of GR in liver and intestine returned to the control level. 【Conclusion】 The study indicated that GR participated in the stress response process of resisting hunger stress of A. dabryanus. [ABSTRACT FROM AUTHOR]

[Objective] To study the biological functions of antimicrobial peptides from the plateau loach. [Methods] The LEAP-2 gene sequence was obtained through the transcriptome sequencing database of the plateau loach. [Result] The cDNA sequence is 2253 bp, in which the 5'uncompiled region (UTR) is 270 bp, the 3'UTR is 1698 bp, the open reading frame is 285 bp, and it encodes 94 amino acids. The signal peptide prediction results show that the LEAP-2 signal peptide contains 28 amino acid residues. The LEAP-2 of the plateau loach-like catfish and the LEAP-2 of the Tibetan plateau loach are clustered together with a confidence of 99%. The tissue distribution results show that LEAP-2 is expressed in 11 tissues including gills, kidneys, liver, muscles, stomach, brain, intestines, spleen, skin, eyes, and heart of healthy loach. The expression in the liver of Catfish Plateau Loach is the highest, which is more than 2000 times the expression in the gills. Under the action of Edwardsiella tarda, the expression of LEAP-2 mRNA in the plateau loach showed different trends in various immune tissues. In the skin, gills and intestines of mucosal-related tissues, LEAP-2 was significantly up-regulated after bacterial infection (P<0.05). In the spleen, liver, and kidney of systemic immune tissues, LEAP-2 in the liver was significantly up-regulated at 24 h after bacterial infection (P<0.05), and then decreased; LEAP-2 in the spleen first decreased, and then significantly increased. (P<0.05), and finally returned to normal expression level; LEAP-2 in the kidney was up-regulated expression at 96 h of challenge (P<0.05). [Conclusion] LEAP-2 is involved in the biological process of the body against infection by pathogenic bacteria. [ABSTRACT FROM AUTHOR]