Heat stress induced by global warming has damaged the well-being of aquatic animals. The skin tissue plays a crucial role as a defense barrier to protect organism, however, little is known about the effect of heat stress on fish skin, particularly in cold-water fish species. Here, we investigated the effects of mild heat stress (24°C, MS) and high heat stress (28°C, HS) on Siberian sturgeon skin using RNA-seq, histological observation, and microbial diversity analysis. In RNA-seq, 8,819 differentially expressed genes (DEGs) in MS vs. C group and 12,814 DEGs in HS vs. C group were acquired, of which the MS vs. C and HS vs. C groups shared 3,903 DEGs, but only 1,652 DEGs were successfully annotated. The shared DEGs were significantly enriched in pathways associating with mucins synthesis. Histological observation showed that the heat stresses significantly reduced the number of skin mucous cells and induced the damages of epidermis. The microbial diversity analysis elicited that heat stress markedly disrupted the diversity and abundance of skin microbiota by increasing of potential pathogens (Vibrionimonas, Mesorhizobium, and Phyllobacterium) and decreasing of probiotics (Bradyrhizobium and Methylovirgula). In conclusion, this study reveals that heat stress causes adverse effects on sturgeon skin, reflecting in decreasing the mucus secretion and disordering the mucosal microbiota, which may contribute to develop the preventive strategy for heat stress caused by global warming.

The hybrid sturgeon Acipenser baerii × A. schrenckii is the most widely cultured commercial sturgeon in China. However, its morphological similarity to the parental species frequently leads to misuse of germplasm in the breeding process, resulting in a decline in the quality of the sturgeon production. In this study, we have developed a protocol by using mitochondrial DNA barcoding and microsatellite locus analysis for the accurate identification of sturgeon species. Genetic distance and phylogenetic analysis based on the mitochondrial COI segment showed that A. baerii exhibited the closest genetic relationship with orthogonal individuals A. baerii (♀) × A. schrenckii (♂). Conversely, A. schrenckii displayed the highest genetic similarity with reciprocal individuals A. schrenckii (♀) × A. baerii (♂). Additionally, genetic structure analysis and factor correlation analysis (FCA) were conducted using six microsatellite loci among 100 samples, including eight species and two hybrid sturgeon. The results showed that all samples, encompassing both hybrid sturgeon (A. baerii × A. schrenckii) and their parental species, were accurately grouped into ten clusters, thereby validating the precision of this species assignment method.

The Procambarus clarkii production sector in Sichuan Province, China, is experiencing rapid growth. However, the industry faces significant challenges, including on-farm breeding and the widespread “Catch Big, Keep Small” farming practice, which have led to substantial genetic degradation within P. clarkii populations. Moreover, the uncertainty surrounding the origins of breeding stocks poses an additional obstacle to the local selection and cultivation of high-quality juvenile P. clarkii. With the objective of inferring the genetic lineage of cultivated P. clarkii in Sichuan, twelve microsatellite loci were employed to investigate the genetic characters of six P. clarkii populations from Sichuan and two from Hubei Province, China. The results revealed that the Sichuan populations exhibited higher levels of heterozygosity (Ho = 0.549~0.699, He = 0.547~0.607) and genetic diversity than the Hubei populations (Na = 4.00~5.250, PIC = 0.467~0.535). Notably, the DY population located in northeastern Sichuan showed the highest heterozygosity (Ho = 0.699, He = 0.607) and genetic diversity (Na = 5.250, PIC = 0.535) among the eight populations. Population structure, principal coordinate analysis and clustering analysis illuminated a close genetic relationship between the Qionglai population in Sichuan and the Jianli population in Hubei. Additionally, the remaining five Sichuan populations (Luxian, Nanxi, Xingwen, Neijiang and Daying) exhibited strong genetic affinity with the QianJiang population in Hubei, and particularly high genetic exchange may have occurred between Daying and Qianjiang (Fst = 0.001, Nm = 217.141). These results suggest that the primary cultivated P. clarkii populations in Sichuan likely originated from Qianjiang and Jianli counties in Hubei, with Qianjiang contributing a more substantial proportion. The genetic diversity of Sichuan populations was higher than those of some other Chinese P. clarkii farming provinces and even some native populations. Specifically, the Daying population emerges as a potential breeding germplasm source for crayfish in Sichuan. In contrast, the Qionglai population exhibits relatively low genetic diversity, highlighting the need for strategic enhancement through interactions with other populations to promote diversity and resilience. Furthermore, fostering genetic exchange among locally cultivated populations within the southern Sichuan basin is strategic to elevate the quality of P. clarkii germplasm resources.

Saccharum spontaneum is a wild germplasm resource of the genus Saccharum that has many valuable traits. Ty1-copia retrotransposons constitute a large proportion of plant genomes and affect genome sequence organization and evolution. This study aims to analyze the sequence heterogeneity, phylogenetic diversity, copy number, and chromosomal dispersion patterns of Ty1-copia retrotransposons in S. spontaneum. A total of 44 Ty1-copia reverse transcriptase subclones isolated from S. spontaneum showed a range of heterogeneity, and all sequences were A-T rich, averaging approximately 54.59%. Phylogenetic analysis divided the 44 reverse transcriptase sequences into 5 distinct lineages (Retrofit/Ale, Sire/Maximus, Bianca, Tork/TAR, and Ty1-copia like). Dot-blot hybridization revealed that Ty1-copia retrotransposons consisted of a significant component of approximately 38,900 copies and 16,300 copies per genome in the accessions YN82-114 (2n = 10x = 80) and AP85-441 (2n = 4x = 32), respectively. The results of a local blast analysis showed that there are 15,069 Ty1-copia retrotransposon copies in the genome of AP85-441, of which the Retrofit/Ale lineage had the highest copy number, followed by the Tork/TAR, Sire/Maximus, and Bianca lineages. Furthermore, both FISH and the local blast analysis with AP85-441 genomic data demonstrated that the Ty1-copia retrotransposons were unevenly distributed throughout the chromosomes. Taken together, this study provides insights into the role of Ty1-copia retrotransposons in the evolution and organization of the S. spontaneum genome.