Search

The ridgetail white prawn (Exopalaemon carinicauda) belongs to the family Palaemonidae and genus Exopalaemon. Owing to its significant economic value and excellent nutritional properties, it is an important species for the development of saltwater aquaculture models in China. In this study, 160 individuals were collected from four wild populations and one artificially selected population using consolidated mitochondrial cytochrome b(mt-cyt b), and microsatellite molecular markers. The results showed that the hatcheries had lower genetic diversity than the wild samples, both at the levels of mt-cyt b(haplotype diversity: 0.123 VS0.572; nucleotide diversity: 0.0003 VS0.0014) and microsatellite (expected heterozygosity: 0.672 VS0.752). Among the four wild populations, the Ningbo population sampled from the East China Sea showed higher genetic diversity in both mt-cyt band microsatellites. A pairwise comparison of genetic differentiation coefficients revealed that the artificially selected population had not genetically diverged from the Cangzhou and Rizhao populations. However, the Ningbo population exhibited moderate to high genetic differentiation (compared to other populations), whereas the Zhanjiang population showed a high level of genetic differentiation, indicating a distinct geographical distribution pattern. Structural analysis revealed the presence of three lineage clusters in all current populations, and the artificially selected population predominantly consisted of lineage 3, accounting for 71.68 % of the population. Currently, the effective population size of hatcheries was <50, rendering them susceptible to the genetic threat of inbreeding depression. These findings provide a scientific basis for the conservation of wild germplasm resources of E. carinicaudaand inform future breeding and management strategies for improved varieties.

Cottonseed meal has been one of the predominant protein feedstuffs used in aqua feed, which contains gossypol. It is well known that gossypol, a natural polyphenolic compound found in seeds, can be toxic to fish. The toxicity of gossypol persists even after a recovery period; however, the underlying mechanism remains largely unknown. To investigate the toxic mechanism of gossypol after the recovery period, Cyprinus carpiowere administered a continuous oral dose of 20mg/kg·d gossypol (gossypol acetate dose/fish weight·d) for one week, followed by a two-week recovery period. The spleen index, spleen morphology, lysozyme (LZM) activity, acid phosphatase (ACP) activity and nitric oxide (NO) concentration were obviously changed in the spleens of C. carpioafter two weeks of recovery. Then, miRNA sequencing identified 22 differentially expressed miRNAs in the spleens of C. carpiotwo weeks after the gossypol treatment. The mRNA expression levels of immune-associated genes were significantly increased in the spleens after recovery. MiR-194 was chosen for future study through a search of existing literature and an analysis of miRNA and mRNA expression levels. To further characterize the potential target of miR-194, we identified putative miR-194 binding sites in the 3'UTR of myeloid differentiation factor 88a (MyD88a). Dual-luciferase reporter assays revealed that miR-194 downregulated the expression level of MyD88a through binding to seed-matching sequence in the 3′ UTR of MyD88a. Moreover, C. carpiowere intraperitoneally administered with miR-194 antagomir. Furthermore, down-regulation of miR-194 increased the expression levels of MyD88a and some pro-inflammatory cytokines and anti-inflammatory cytokines. Altogether, the results demonstrate miR-194 can target MyD88a to regulate the immune response of C. carpioafter a two-week recovery period following gossypol administration.