Functional Characterization of Two β-Hexosaminidase A Isoforms During Ovarian Development in Macrobrachium nipponense

In this study, we identified two β-hexosaminidase A isoforms (Mn-HexA1 and Mn-HexA2) in Macrobrachium nipponense through bioinformatics analysis and characterized their phylogenetic relationships. The open reading frames of Mn-HexA1 and Mn-HexA2 were 1641 bp (encoding 546 amino acids) and 1473 bp (encoding 490 amino acids), respectively. Both isoforms exhibited high conservation, sharing five identical functional domains, with 58.43% amino acid sequence similarity. Quantitative PCR analysis revealed that Mn-HexA1 expression was significantly higher than Mn-HexA2 across all developmental stages and tissues. During embryonic development, Mn-HexA1 showed elevated expression at the ZS, L15, and PL10, while Mn-HexA2 was upregulated only at L15 and PL10. In the breeding season and non-breeding season, Mn-HexA1 and Mn-HexA2 were predominantly expressed in the hepatopancreas at levels significantly higher than in other tissues. Moreover, their expression in most tissues was higher during the breeding season than in the non-breeding season. RNA interference experiments revealed that knockdown of both Mn-HexA isoforms significantly accelerated ovarian development in M. nipponense, with the Mn-HexA1-silenced group exhibiting faster progression than the Mn-HexA2-silenced group. These results demonstrate that Mn-HexA genes function as negative regulators of ovarian maturation, with Mn-HexA1 exerting a stronger inhibitory effect than Mn-HexA2.