International Journal of Aquaculture, 2025, Vol.15, No.2, 45-56 http://www.aquapublisher.com/index.php/ija 48 and traits, endocrine hormone genes that control gender differentiation and maturation of shrimps, such as gonad inhibitor (GIH), androgen effector gene (IAG), have been sequenced and identified in different shrimp species (Ferdous et al., 2012). 3.3 Transcriptomics and the construction of genomic databases In addition to genome sequencing, transcriptomic research has played a crucial role in elucidating gene functions in shrimp. Transcriptome sequencing (RNA-Seq) can reveal gene expression profiles in specific tissues, developmental stages, or under stress conditions, thereby aiding in the identification of trait-associated genes and regulatory networks. For example, a transcriptomic analysis of Chinese shrimp (Fenneropenaeus chinensis) under heat stress identified a series of heat shock proteins and antioxidant enzyme genes, deepening our understanding of the mechanisms underlying high-temperature stress responses (Tang et al., 2022). Active research is also being conducted on reproductive development. One study comparing the ovarian transcriptomes of wild-caught and farmed tiger prawns (Penaeus monodon) found that genes related to vitellogenin synthesis were significantly upregulated in wild individuals. Additionally, a transcriptomic analysis of male and female gonads in banana shrimp (Fenneropenaeus merguiensis) identified numerous sex-differentially expressed genes, including key enzymes involved in oogenesis and factors regulating male reproduction (Saetan et al., 2016). These data provide valuable insights into sex determination and reproductive regulation in shrimp. To better manage and utilize the vast amount of omics data, researchers are also building genomic and transcriptomic databases for shrimp. Several international public databases (such as NCBI's Genome and SRA repositories) have included genome sequences and transcriptomic datasets of various shrimp species, enabling researchers to perform comparative analyses and identify candidate genes. In China, some institutions have also developed integrated databases for aquatic animals, combining key gene sequences, QTL information, and expression profiles into unified platforms. Through these databases, breeding experts can query sequence variations and expression patterns of target trait-related genes, thus supporting informed breeding decisions. 4 Current Status of CRISPR Technology in Shrimp 4.1 Research cases of successful application of CRISPR in shrimp 4.1.1 CRISPR/Cas9 edits the Vitellogeningene of Penaeus monodonto regulate ovarian development For a long time, in breeding practice, the eye stalk is often cut off to remove gonad inhibitors, thereby promoting the maturation of the shrimp gonad. However, this method is traumatic and cumbersome to individual shrimps. Using CRISPR gene editing to directly modify genes that control reproduction is expected to become a more refined and effective alternative. One of the key factors in ovarian development of Penaeus monodon is Vitellogenin (Vg) and its regulatory pathway. Vg is synthesized in the hepatopancreas of female shrimp and delivered to the ovaries, providing nutrients to oocytes. Generally, gonadal inhibitor (GIH) secreted in the stalk inhibits Vg synthesis, thereby delaying ovarian development (Ferdous et al., 2022). Based on this mechanism, the researchers envisioned that the Vg gene itself or the upstreamGIHreceptor gene was knocked out by CRISPR to directly affect the ovarian maturation process. At present, preliminary studies have tried to apply CRISPR/Cas9 to target reproductive-related genes in pimples. In an editing study on the P. monodon yolk proteogen gene, researchers designed multiple exon regions of the sgRNA targeting Vg gene, and introduced Cas9 mRNA and sgRNA into the larvae through microinjection, trying to induce the function loss of Vg gene. It was found that some CRISPR-treated female shrimp individuals had reduced Vg plasma content and delayed ovarian development, which was consistent with the expected functional deletion effect. There are also studies that select key genes targeting GIH signaling pathways. For example, Thai scholars used RNA interference to knock down the GIHgene of P. monodonand observed that the development of ovarians of female shrimps was accelerated. Once the functions of these key genes are confirmed by CRISPR, we are expected to cultivate "no eye-cutting" breeding shrimp species to improve reproductive efficiency and reduce damage to individuals.
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