International Journal of Marine Science, 2025, Vol.15, No.3, 154-166 http://www.aquapublisher.com/index.php/ijms 161 also profoundly affects the changes in gene function. Sequence changes in cis-regulatory elements such as promoters and enhancers often change the spatiotemporal expression pattern of genes, thereby causing phenotype differences. In shrimp evolution, we observed that some regulatory elements and the transcription factors they regulated have a coordinated evolution. A typical case is the role of simple repeat sequences (SSRs) in regulatory regions: researchers used multiomics to find that some SSRs in the genome of Pacific white shrimp were inserted into gene promoters or introns, resulting in differences in expression of nearby genes under different environments. For example, when the promoter of an osmotic regulatory gene contains variable length AT repeats, its expression level under low salt stress is significantly higher than that of alleles without duplicates. This indicates that slight changes in regulatory elements (such as changes in repeat length) can affect transcription intensity. At the same time, transcription factors involved in binding these elements also responded in evolution. Either the DNA binding domain of the transcription factor has a mutation that matches the regulatory sequence, or the expression profile changes to adapt to the presence of new enhancers. This "co-evolution" of regulatory factors and target sequences ensures the homeostasis of the gene expression regulatory network. Foxl2, a transcription factor associated with estrogen receptor in shrimp, has slightly different DNA binding sites in different species. Correspondingly, the regulatory elements retained on the Foxl2 promoter in each species also differ, possibly reflecting the remodeling of the Foxl2-target gene axis in different evolutionary contexts. 7 Case Analysis 7.1 Evolution and functional analysis of the IGF signaling pathway in Pacific white shrimp As an important breeding species, the growth regulation mechanism of Pacific white shrimp has always attracted much attention. In recent years, a series of results have been achieved in the study of insulin-like growth factor (IGF) signaling pathways. Three IGF-binding protein (IGFBP) genes in the IGF signaling pathway were identified in vannerbine shrimp and their structural and evolutionary relationships were compared. The results show that LvIGFBP1 has a Kazal-type serine protease inhibitory domain that is not found in mammalian IGFBP, showing structural innovations unique to crustaceans. This structural evolution may confer new regulatory functions to IGFBP1, such as binding to IGF and participating in trypsin inhibition, thereby connecting growth signals to digestive metabolic pathways (speculative mechanisms). Functionally, IGFBP1 was expressed at high levels in most tissues, and RNAi knockdown experiments resulted in hindering growth of shrimp, and their weight gain was significantly lower than that of the control group. This proves that IGFBP1 is a key positive regulator of growth promoting in the IGF pathway. While IGFBP2 and IGFBP3 are mainly expressed in low quantities in blood cells, the impact of knockdown on overall growth is not obvious, suggesting that they may play more roles in local environments or are partially redundant in function (Pang et al., 2021). Evolutionary analysis speculates that the other differentiates into the RTK2 type. LvRTK2 is highly conserved in shrimps, but there is no corresponding homologue in hexapods such as insects, indicating that its function may be unique to crustaceans. Functional experiments show that interfering with LvRTK2 will reduce the blood sugar removal efficiency and growth rate of shrimp after feeding. Combined with the fact that this receptor is mainly expressed in the hepatopancreas and reproductive organs, it is speculated that LvRTK2 is not only involved in general growth and metabolism, but may also connect nutritional status with reproductive energy distribution - promoting growth and reproductive development through the IIS pathway when nutrients are sufficient, and inhibiting reproductive investment when nutrients are scarce to preserve one's own survival. 7.2 Comparative evolutionary analysis of genes related to ovarian development in black tiger shrimp Black tiger shrimp (Penaeus monodon) is one of the important breeding shrimps, and its ovarian maturation is a key step in achieving reproduction. Researchers conducted multi-level comparative analysis on the development of ovarian ovaries of Black tiger shrimp. On the one hand, comparison of ovarian gene expression under different treatment conditions within the same species reveals the molecular mechanisms that regulate ovarian maturity. Experts used transcriptome technology to compare the similarities and differences in ovarian gene expression in black tiger shrimp under ocular stalk removal and feeding live bait. The results showed that ovaries with only the stalk removal (simulated to remove the inhibitor GIH) and ovaries with only the extra fertile live bait were not able to reach full maturity; while in the treatment group that performed stalk removal and live bait enhancement,
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