International Journal of Marine Science, 2025, Vol.15, No.3, 154-166 http://www.aquapublisher.com/index.php/ijms 156 databases and opened to scientific researchers. The NCBI genome database contains the assembly sequence and gene annotation information of species such as Vannebane prawns, squids, and biosparagus Rohman, which can be obtained through Bioproject or Genome numbers. In addition to comprehensive databases, professional databases for specific groups have also been established one after another. For example, the "PenBase" database specifically includes sequence and functional information of the shrimp antibacterial peptide (penaedin) family, providing a convenient tool for the study of shrimp immune genes (Senapin et al., 2012). Some scholars in China have established a shrimp breeding database to collect family breeding pedigrees, phenotypic traits and gene marker information to facilitate genetic evaluation and seed selection decisions. 3 Functional Classification and Expression Characteristics of Growth-Related genes 3.1 The main gene classes and mechanisms of action that regulate growth (such as GH, IGF, mTOR pathways) The growth regulation of shrimp involves multi-level gene networks such as endocrine hormones, nutritional metabolism, and cell proliferation. Among them, the insulin/insulin-like growth factor signaling pathway (IIS pathway) is believed to play a central role in crustacean growth and metabolism. The IIS pathway includes key signal nodes such as insulin-like growth factor (IGF), insulin receptor (IR), downstream PI3K-AKT and mTOR. Studies have shown that the shrimp IIS pathway gene has unique evolutionary characteristics: three insulin-like growth factor binding protein (IGFBP) genes were identified in the Pacific white shrimp genome, and their structures were different. Among them, IGFBP1 contains three functional domains IB, Kazal and IgC2, while IGFBP2 and IGFBP3 only contain the IB domain. RNA interference experiments found that knockdown of IGFBP1 significantly reduced the weight gain rate in shrimp, indicating that IGFBP1 plays a key role in promoting growth (Pang et al., 2021). In addition, shrimp insulin receptor genes also show evolutionary innovation. Su et al. (2024) cloned a novel insulin-like receptor LvRTK2 in vannerbine shrimp, which belongs to the unreported subtype of the insulin receptor tyrosine kinase family. Expression and functional analysis showed that LvRTK2 was mainly highly expressed in digestive organs and reproductive tissues. After administration of exogenous glucose and starvation, LvRTK2 mediates the regulation of sugar metabolism in shrimps; long-term and short-term interference with the LvRTK2 gene both lead to a decrease in shrimp growth rate (Su et al., 2024). This suggests that the receptor is not only involved in growth but also closely related to energy balance. In addition to the IIS pathway, the ecdysterone (20E) signaling pathway also affects shrimp growth, because crustaceans can only continue to grow after molting. 3.2 Analysis of expression profiles in tissue and development stages To understand the functions of growth-related genes, researchers often analyze gene expression profiles at different tissues and developmental stages through the transcriptome. Overall, shrimp growth regulation genes are highly expressed in energy-metabolic organs (such as hepatopancreas, muscles) and endocrine organs. The newly discovered LvRTK2 receptor is expressed in both the ovaries of female shrimp and the testes of male shrimp, and is expressed in digestive tissues such as the hepatopancreas. This distribution pattern suggests that the receptor not only mediates growth metabolic signals, but may also be involved in the regulation of gonad development. In terms of developmental stage, the expression of many growth-related genes changes dynamically with the development of shrimp body (Figure 1). Taking the example of muscular development-related genes, transcriptome studies show that during the transition from larval to shrimp, structural myoproteins such as myosin subunit genes are gradually upregulated to meet higher exercise needs (Xia et al., 2023). Correspondingly, genes that affect the cell growth cycle are expressed higher in the juvenile period and tend to decline in the adult stage, which is consistent with the phenomenon that individual growth rate slows down with development. In addition, some genes related to peeling and regeneration (such as chitinase, chitinase) are significantly upregulated in the early stage of molting and rapidly decline after molting, reflecting the cyclical changes in the developmental stage (Gao et al., 2017). 3.3 Effects of exogenous factors such as nutrition, temperature, and density on gene expression Environmental factors often act on shrimp growth performance by affecting gene expression. Nutritional levels
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