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

In this study, we identified two <i>β-hexosaminidase A</i> isoforms (<i>Mn-HexA1</i> and <i>Mn-HexA2</i>) in <i>Macrobrachium nipponense</i> through bioinformatics analysis and characterized their phylogenetic relationships. The open reading frames of <i>Mn-HexA1</i> and <i>Mn-HexA2</i> 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 <i>Mn-HexA1</i> expression was significantly higher than <i>Mn-HexA2</i> across all developmental stages and tissues. During embryonic development, <i>Mn-HexA1</i> showed elevated expression at the ZS, L15, and PL10, while <i>Mn-HexA2</i> was upregulated only at L15 and PL10. In the breeding season and non-breeding season, <i>Mn-HexA1</i> and <i>Mn-HexA2</i> 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. <i>RNA interference</i> experiments revealed that knockdown of both <i>Mn-HexA</i> isoforms significantly accelerated ovarian development in <i>M. nipponense</i>, with the <i>Mn-HexA1</i>-silenced group exhibiting faster progression than the <i>Mn-HexA2</i>-silenced group. These results demonstrate that <i>Mn-HexA</i> genes function as negative regulators of ovarian maturation, with <i>Mn-HexA1</i> exerting a stronger inhibitory effect than <i>Mn-HexA2</i>.