International Journal of Aquaculture, 2025, Vol.15, No.2, 45-56 http://www.aquapublisher.com/index.php/ija 51 5.2 Research and editing of the functions of disease-resistant genes After digging out disease-resistant candidate genes, they need to verify their role through functional research. CRISPR is the weapon in this link. In the past, RNAi was used to silence genes in shrimps for short-term shrimps, but the efficiency and specificity of RNAi in shrimps often affect the interpretation of the results. In contrast, CRISPR knockout can produce stable gene deletion effects, which more effectively demonstrates the causal relationship between gene and phenotype. In recent years, CRISPR research on shrimp disease-resistant genes has gradually begun. The C-type Lectin family of shrimps, which encode pattern recognition receptors, are involved in pathogen recognition and phagocytosis. There are reports that knocking down a C-type lectin will increase shrimp's resistance to leucorrhea virus, suggesting that its normal function may be used by the virus to help invade (Lai et al., 2013). If the corresponding Lectin gene is knocked out with CRISPR, shrimp may become resistant to the virus. Some experiments are currently underway. For example, antioxidant enzyme genes play a role in protecting cells in oxidative stress caused by pathogen infection. Research has used CRISPR to knock out the stress response factor gene in vannabine shrimp to activate the Nrf2 pathway, thereby improving the antioxidant ability of cells. The results showed that the mortality rate of gene-edited cells was reduced under Vibrio infection (Gui et al., 2016). These attempts show that the idea of enhancing shrimp's autoimmune defense through gene editing is feasible. 5.3 Feasibility and challenges in building a disease-resistant strain Using CRISPR to obtain disease-resistant mutant individuals is only the first step, and cultivating them into a stable genetic disease-resistant strain is the ultimate goal. There are already some successful cases in this regard: researchers have cultivated animal strains such as parasite-resistant cattle, pigs, etc. through gene editing, proving that the route from mutants to strains is feasible (Islam et al., 2020). Similarly, in shrimps, once a founding individual (F0 generation) that resists disease mutations is obtained, the mutations can be fixed to the population in a homozygous state through appropriate hybridization and breeding. Specifically, male shrimp carrying disease-resistant mutations can be mated with wild-type female shrimp to obtain F1 heterozygotes, and then mates are mated or backcrossed to screen out individuals with homozygote mutations. Due to the large amount of egg laying in a single time, this screening is affordable in quantity. In terms of screening methods, individual genotypes can be quickly identified by PCR and sequencing, without the need to take generations of time like traditional breeding. However, the challenge cannot be ignored. Disease resistance is usually a complex trait that often involves the synergy of multiple genes. Mutations in a single gene may not be sufficient to provide comprehensive resistance. Secondly, disease-resistant mutations may pay a certain price to grow or reproduce. According to evolutionary biology theory, increased disease resistance is sometimes accompanied by a decrease in growth rate or a change in energy distribution. For example, a continuously activated immune system consumes additional resources. When building disease-resistant strains, it is necessary to observe whether mutations bring negative traits, and if so, they need to be balanced in breeding. There are also factors from regulation and the public that are part of the challenge. Once the disease-resistant gene-edited shrimp strain is successfully cultivated, its promotion and application needs to be approved by policy and market recognition. Regulators will pay attention to the performance of these shrimps in the ecological environment, and are worried about whether they will have a competitive advantage or genetic infiltration to the wild population if the disease-resistant genetically modified shrimp escapes. Although gene-edited shrimp does not contain exogenous genes, it is still necessary to prove that it will not become a risk of invasive species because disease-resistant mutations may improve survival. 6 Application Prospects of CRISPR in the Regulation of Shrimp Growth and Reproduction 6.1 Editing of genes related to control growth rate Growth speed directly determines the length of the breeding cycle and the yield, and is one of the important traits of aquatic animal breeding. Studies have shown that crustacean ecstasy inhibitor hormone (MIH) plays a key role in maintaining molting cycle and body length growth. In the MIH knockout experiment of ridge-tailed white shrimp, the frequency of molting of mutant shrimp increased and the development period of larval bodies was
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