Further evidence for paternal DNA transmission in gynogenetic grass carp

Deciphering male influence in gynogenetic Pengze crucian carp (Carassius auratus var. pengsenensis): insights from Nanopore sequencing of structural variations

In this study, we investigate gynogenetic reproduction in Pengze Crucian Carp (Carassius auratus var. pengsenensis) using third-generation Nanopore sequencing to uncover structural variations (SVs) in offspring. Our objective was to understand the role of male genetic material in gynogenesis by examining the genomes of both parents and their offspring. We discovered a notable number of male-specific structural variations (MSSVs): 1,195 to 1,709 MSSVs in homologous offspring, accounting for approximately 0.52%-0.60% of their detected SVs, and 236 to 350 MSSVs in heterologous offspring, making up about 0.10%-0.13%. These results highlight the significant influence of male genetic material on the genetic composition of offspring, particularly in homologous pairs, challenging the traditional view of asexual reproduction. The gene annotation of MSSVs revealed their presence in critical gene regions, indicating potential functional impacts. Specifically, we found 5 MSSVs in the exonic regions of protein-coding genes in homologous offspring, suggesting possible direct effects on protein structure and function. Validation of an MSSV in the exonic region of the polyunsaturated fatty acid 5-lipoxygenase gene confirmed male genetic material transmission in some offspring. This study underscores the importance of further research on the genetic diversity and gynogenesis mechanisms, providing valuable insights for reproductive biology, aquaculture, and fostering innovation in biological research and aquaculture practices.

Molecular Characterization and Nutrition Regulation of the Neutral Amino Acid Transporter ASCT2 in Triploid Crucian Carp

AlaSerCys Transporter 2 (ASCT2), encoded by the SLC1A5 gene, plays an important role in the absorption of glutamine. In this study, the full-length cDNA sequence of ASCT2 was cloned from triploid crucian carp. It encodes 539 amino acid residues and a stop codon. Phylogenetic analysis revealed that the sequences of the ASCT2 ORF region in cyprinid fishes shared high sequence homology. Comparing the abundance of ASCT2 in different tissues, we found its expression level in muscle was significantly higher than that in intestine (p < 0.05). In addition, the expression levels of ASCT2 also appeared different in diurnal variation. Then we found the addition of 2.5% glutamate in a feeding diet significantly increased the expression levels of ASCT2 in intestine and muscle (p < 0.05). However, in glutamine experiments, the muscle showed the highest expression level of ASCT2 when fish were fed the diet containing 3.0% glutamine (p < 0.05). In vitro, ASCT2 was sensitive to glutamine and its expression level appeared down-regulated when the addition of glutamine was added to 0.1 mg/mL. Finally, we found that the diet with 29% protein level significantly increased the expression level of ASCT2 in intestine (p < 0.05). Nevertheless, different protein sources (fish meal and soybean meal) had no significant effect on the expression levels of ASCT2 in intestine and muscle (p > 0.05). These results provided data for the study of ASCT2 in triploid crucian carp regulated by feeding nutrition, which had a potential application in improving feed formulation in aquaculture.