Search Results (3)

High-alkalinity water bodies can disrupt normal ammonia metabolism in fish, leading to ammonia poisoning. In China, there exists a highly tolerant group of Amur ide (Leuciscus waleckii) that can survive in extreme alkaline lakes with alkalinity up to 53.57 mM (pH 9.6), making it an excellent model for elucidating the high-alkalinity tolerance mechanism in fish. We have discovered that this species has evolved a special ammonia excretion mechanism to maintain ammonia efflux in high-alkalinity environments. Compared to the freshwater forms of Amur ide, the ammonia excretion protein RHBG plays a prominent role in the ammonia excretion process of the alkali forms of Amur ide; however, the regulatory mechanism of RHBG expression in fish remains unclear. Through DNA pull-down, RNA-Seq, qPCR, Western blotting, immunofluorescence, and dual-luciferase reporter assays, this study demonstrates that the transcription factor HIF1A can inversely regulate the expression of Rhbg by binding to its promoter region, thereby participating in the high-alkalinity adaptation process of fish. The findings of this study provide a theoretical basis for elucidating the ammonia excretion mechanism and revealing the alkalinity tolerance mechanism in fish. Full article

Aquaporin (Aqp) is a transmembrane-specific channel for small molecules that help in regulating homeostasis in fishes when adapting to changing environments, but its role in Amur ide’s response to alkaline stress is yet to be revealed. Therefore, the purpose of this study is to investigate the response of the Aqp gene exposed to alkaline water in Amur ide (Leuciscus waleckii) using a genome-transcriptional assay. Based on the results, we classified the Aqps of the L. waleckii (LwAqps) genome and analyzed its transcriptional expression profile and genetic evolution under carbonate alkalinity stress. A total of 18 Aqp genes were identified in four grades in L. waleckii. The highest Aqp gene expression was found in the gill and kidney of L. waleckii from the Wusuli River (WSL) in comparison to those in the Dali Lake (DL), whereas aqp3a, -3ap1, -7, and -9a expressions were found at intensively higher levels in the gill rather than in the kidneys and livers. The experiment of L. waleckii under alkalinity stress (carbonate alkalinity 50 mmol·L⁻¹) and its recovery showed that the expressions of aqp0a, -3a, -3ap1, -7, -8aa, and -9a were upregulated in alkaline water and downregulated in freshwater. We identified 1460 single nucleotide polymorphism (SNP) markers in the Aqp genes. The average value of Fst of SNP markers in the CDS region was 0.177 ± 0.256, and the first 5% SNPs were identified at aqp3a and -11b. Residue Ser66 does not bring about an overall change in the three-dimensional structure of Aqp3a, but may change the penetration of solutes across the membrane. This indicates that Aqp genes are involved in the response of L. waleckii to alkaline stress, and aqp3a is one of the key genes involved in regulating L. waleckii’s adaptation to alkaline environments. Full article

Amur ide (Leuciscus waleckii), an important aquaculture species, inhabits neutral freshwater but can tolerate high salinity or alkalinity. As an extreme example, the population in Dali Nor lake inhabits alkalized soda water permanently, and migrates from alkaline water to neutral freshwater to spawn. In this study, we performed comparative transcriptome profiling study on the livers of Amur ide to interrogate the expression differences between the population that permanently inhabit freshwater in Ganggeng Nor lake (FW) and the spawning population that recently migrated from alkaline water into freshwater (SM). A total of 637,234,880 reads were generated, resulting in 53,440 assembled contigs that were used as reference sequences. Comparisons of these transcriptome files revealed 444 unigenes with significant differential expression (p-value ≤ 0.01, fold-change ≥ 2), including 246 genes that were up-regulated in SM and 198 genes that were up-regulated in FW. The gene ontology (GO) enrichment analysis and KEGG pathway analysis indicated that the mTOR signaling pathway, Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway, and oxidative phosphorylation were highly likely to affect physiological changes during spawning migration. Overall, this study demonstrates that transcriptome changes played a role in Amur ide spawning migration. These results provide a foundation for further analyses on the physiological and molecular mechanisms underlying Amur ide spawning migration. Full article