Based on obtaining mstnb gene knockout in Pelteobagrus fulvidraco, a study on the effect of the mstn gene on skeletal morphology and growth was performed by comparing the number and length of the vertebrae of mutant and wild-type fish in a sibling group of P. fulvidraco, combined with the differences in cells at the level of vertebral skeletal tissue. It was found that mstnb gene knockdown resulted in a reduction in the number of vertebrae, the length, and the intervertebral distance in P. fulvidraco, and these changes may be the underlying cause of the shorter body length in mutant P. fulvidraco. Further, histological comparison of the same sites in the mstn mutant and wild groups of P. fulvidraco also revealed that the number and density of osteocytes were greater in mstnb knockout P. fulvidraco than in wild-type P. fulvidraco. Our results demonstrated that when using genome editing technology to breed new lines, the effects of knockout need to be analyzed comprehensively and may have some unexpected effects due to insufficient study of the function of certain genes.

The Asian yellow pond turtle (Mauremys mutica) is widely traded in China, and its artificial breeding has now become a major industry. However, the insufficient offspring supply and reproductive decline of farmed turtles make the wild turtles more vulnerable. The present study was mainly designed to quantify the fecundity of M. mutica and attempt to screen for good reproductive performance in females. The genetic variability of the population and its genetic structure were also analysed. The parent–offspring relationships of all offspring in four consecutive years were confirmed using sixteen microsatellite loci. The genetic variability between the parents and offspring was low, and offspring of different years also showed little variability. We summarised the reproductive results of all females and counted the annual number of offspring and the variation in the number of offspring. The females were then divided into three types (stable, undulating and levelling off) according to the continuity. We selected seven females with good reproductive ability, which provided 16.94% of the annual contributions, while there were two females that had no offspring in four years. We also analysed the possible reasons for this difference and the importance of carrying out a family survey. This research can provide the basis and materials for the creation of a good reproductive group and the study of the reproductive biology of turtles in M. mutica aquaculture.

Arachidonic acid (ARA) is an indispensable fatty acid for aquatic organisms, playing critical roles in reproductive physiology. This study aimed to evaluate the effects of graded dietary ARA levels on the reproductive performance, tissue fatty acid profiles, plasma sex hormone and prostaglandin concentrations, ovarian molecular responses, and offspring larval quality in female blotched snakehead (Channa maculata). Three experimental diets with ARA levels of 0% (control, C), 1.5% (ARA1.5), and 3.0% (ARA3.0) were formulated and administered to female blotched snakehead for 12 weeks. The results demonstrated that dietary ARA supplementation significantly improved fertilization rate, hatching rate, and larval growth performance, while reducing the larval malformation rate. ARA supplementation enhanced the deposition of ARA, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) in both ovaries and muscle tissues. Plasma levels of sex hormones and prostaglandins (PGE2, PGF2α) were significantly elevated with increasing dietary ARA concentrations. Furthermore, qRT-PCR and Western blot results indicated that ARA supplementation upregulated the expression of genes and proteins in the TGF-β/Smad signaling pathway and steroidogenesis-related genes. Metabolomic analysis identified differential metabolites enriched in arachidonic acid metabolism, the VEGF signaling pathway, and glycolysis/gluconeogenesis in ovaries and larvae, with ARA-derived eicosanoids significantly upregulated. Dietary ARA supplementation was associated with improved reproductive performance, accompanied by reproducible molecular alterations in the ovarian TGF-β/Smad signaling pathway, indicating that this cascade represents a plausible underlying regulatory mechanism for this improvement.