Multidimensional Regulatory Mechanisms of LvChia2 on Growth in the Pacific White Shrimp (Litopenaeus vannamei)

<b>Background</b>: As a globally significant aquaculture species, elucidating the molecular mechanisms underlying the regulation of the Pacific White Shrimp (<i>Litopenaeus vannamei</i>) growth holds substantial scientific and industrial value. This study systematically investigates the role of the <i>LvChia2</i> gene in governing growth and development through a cross-tissue metabolic network approach. <b>Methods</b>: RNA knockdown (RNAi)-mediated knockdown of <i>LvChia2</i> significantly impaired growth performance and triggered a tissue-specific metabolic compensation mechanism. <b>Results</b>: This mechanism was characterized by reduced crude lipid content in muscle and adaptive modulation of lipase (LPS) activities in hepatopancreatic and intestinal tissues, suggesting inter-tissue metabolic coordination. Transcriptomic profiling identified 610 differentially expressed genes (DEGs), forming a three-dimensional regulatory network encompassing "energy metabolism, molt regulation, and nutrient utilization." Key mechanistic insights revealed the following: (1) Enhanced mitochondrial energy transduction through the upregulation of ATP synthase subunits and NADH dehydrogenase (<i>ND-SGDH</i>). (2) The disruption of ecdysteroid signaling pathways via suppression of Krueppel homolog 1 (<i>Kr-h1</i>). (3) The coordinated regulation of nitrogen metabolism through the downregulation of glutamine synthetase and secretory phospholipase A2. These molecular adaptations, coupled with tissue-specific oxidative stress responses, reflect an integrated physiological strategy for environmental adaptation. <b>Conclusions</b>: Notably, this study provides the first evidence in crustaceans of chitinase-mediated growth regulation through cross-tissue metabolic interactions and identifies six core functional genes (<i>ATP5L</i>, <i>ATP5G</i>, <i>ND-SGDH</i>, <i>Kr-h1</i>, <i>GS</i>, <i>sPLA2</i>) as potential targets for molecular breeding. A novel "gut-hepatopancreas axis" energy compensation mechanism is proposed, offering insights into resource allocation during metabolic stress. These findings advance our understanding of crustacean growth regulation and establish a theoretical foundation for precision aquaculture strategies, including genome editing and multi-trait genomic selection.