Search Results (6)

Background/Objectives: Interferon regulatory factors (IRFs) are multifunctional transcription factors that play important roles in the transcriptional regulation of interferons and in the immune response to pathogens. Therefore, studying the interferon system in fish is highly relevant in the prevention and treatment of viral diseases. Methods: In this study, five IRF genes (IRF1, IRF4, IRF5, IRF7 and IRF9) were identified and characterized in Hucho bleekeri, and their expression profiles were determined after LPS and Poly(I:C) treatment. Results: These IRFs have typical DNA-binding domains and IRF-association domains. Amino acid sequence comparison revealed high homology between these IRFs and those of other vertebrates, with the highest homology being with other salmonid fish. Phylogenetic analysis revealed that these IRFs are divided into four subfamilies (IRF1, IRF3, IRF4 and IRF5), with both IRF4 and IRF9 belonging to the IRF4 subfamily. IRF genes were widely expressed in all of the tested tissues, with IRF1, IRF4 and IRF9 being highly expressed in the spleen and kidney and IRF5 and IRF7 highly expressed in the gonads. IRF1, IRF4 and IRF5 expression was induced at different time points post-LPS challenge. IRF7 and IRF9 expression in the spleen and head kidney was not significantly altered by LPS induction. Poly(I:C) treatment altered IRF expression more significantly than LPS treatment. Poly(I:C) significantly altered the spleen and head kidney expression of all five IRFs. Conclusions: These findings reveal the potential role of IRFs in the antiviral response of H. bleekeri and provide a reference for examining signal transduction pathways in the interferon system in fish. Full article

Background: Sichuan taimen (Hucho bleekeri) is a fish species endemic to China’s upper Yangtze River drainage and has significant value as an aquatic resource. It was listed as a first-class state-protected wild animal by the Chinese government due to its very limited distribution and wild population at present. Methods: To elucidate the diversity of microorganisms in rearing water environments for H. bleekeri, metagenomic sequencing was applied to water samples from the Maerkang and Jiguanshan fish farms, where H. bleekeri were reared. Results: The results revealed that Pseudomonadota was the dominant phylum in the microbial communities of the water samples. Among the shared bacterial groups, Cyanobacteriota, Actinomycetota, Planctomycetota, Nitrospirota, and Verrucomicrobiota were significantly enriched in the water environment of Jiguanshan (p < 0.01), while Bacteroidota was more enriched in that of Maerkang (p < 0.01). Additionally, the Shannon diversity and Simpson index of the microbial community in the water environment of Maerkang were lower than in that of Jiguanshan. Conclusions: The present study demonstrated the similarities and differences in the microbial compositions of rearing water environments for H. bleekeri, which are expected to benefit the artificial breeding of H. bleekeri in the future. Full article

Sichuan taimen (Hucho bleekeri Salmonidae) populations are declining, and the status of remnant populations in the Qinling Mountains is poorly known. In this study, eDNA and creel netting were used to estimate the distributions of Sichuan taimen in two upper tributaries of the Hanjiang River. A qPCR assay was applied to detect the eDNA of H. bleekeri, and the presence of Sichuan taimen in the Taibai River, but not in the Xushui River, was confirmed. Sampling during summer achieved a relatively higher detection rate. The utility of eDNA techniques for detecting low-density Sichuan taimen was demonstrated in intricate stream ecosystems. The eDNA method can increase the efficiency of the management of endangered freshwater species, such as Sichuan taimen, by providing reliable distribution data. Full article

Sichuan taimen (Hucho bleekeri) is a national highly protected wild animal that faces significant impacts from habitat degradation and loss. To study the habitat selection by H. bleekeri, data on the Taibai River and the distribution of juvenile H. bleekeri were recorded seasonally between February 2017 and January 2018, and habitat selection was assessed using the suitability curve method. The results indicate that the average distribution density of juvenile H. bleekeri in the Taibai River is 0.08 ± 0.09 ind./m, with an optimal elevation range from 1200 to 1600 m, river sinuosity range from 1.0 to 1.2, and vegetation coverage between 0.7 and 1.0. When choosing a microhabitat, juvenile H. bleekeri individuals tend to inhabit water areas with a water depth of 0.65 ± 0.33 m, flow velocity of 0.50 ± 0.24 m/s, and offshore distance of 7.66 ± 4.25 m. Furthermore, smaller juvenile fish prefer nearshore habitats with lower flow velocities and shallower water depths. The results provide technical support for the protection and restoration of the habitat of H. bleekeri. Full article

Environmental DNA (eDNA) techniques have emerged as a cost-effective and non-invasive strategy for monitoring the distribution of endangered aquatic species. Despite their numerous advantages, operational uncertainty at each step of the process represents a significant challenge that can impact the reliability of results. Hence, the optimization of the eDNA analytic protocol is of utmost importance. In this study, the rare and endangered fish species Sichuan taimen was chosen as the target species to evaluate the concordance between different approaches (tissue, pond, and field water samples) for eDNA detection. The results showed that membrane filtration, collection of a 2-L water sample, and utilization of the DNeasy Tissue and Blood DNA extraction kit were suitable for the analysis of DNA in water samples. Furthermore, the mtDNA D-loop region demonstrated potential as a specific molecular marker for the precise identification of Sichuan taimen. Our results indicated that TaqMan fluorescence PCR can serve as the optimal detection method for reliable identification of target DNA even at extremely low concentrations in the field. This study established an optimized eDNA analysis protocol for Sichuan taimen detection, which will provide the basis for future resource investigations aimed at protection of this endangered aquatic species. Full article

Sichuan taimen (Hucho bleekeri), a critically endangered species, is listed as a first-class protected species in China. The natural population has been missing from most of its known distribution areas for many years but was rediscovered in the Taibai River in 2012, providing an important resource for the conservation stocking of the Sichuan taimen. In this study, 43 wild adult Sichuan taimen collected from the Taibai River were determined for gamete maturity for artificial reproduction using ultrasonography. The echogenicity of the gonads before and after hormonal induction was described to determine broodstock identification, injection dose of hormones, and spawning time. Four batches of artificial breeding were successfully achieved in 2013, 2014, and 2016. Broodstock (19 females and 16 males) spawned with average fertilization and hatching rates reaching 80.2% and 61.0%, respectively. This study demonstrates that ultrasonic imaging is a convenient and efficient method to track the state of gonads of mature Sichuan taimen during artificial reproduction, which will assist in broodstock cultivation, and further large-scale proliferation and effective resource restoration of the Sichuan taimen. Full article