International Journal of Marine Science, 2025, Vol.15, No.1, 1-14 http://www.aquapublisher.com/index.php/ijms 8 aquaculture production in China and Northeast Asia, and its adaptability to low-temperature environments and disease resistance have attracted much attention. Through the analysis of the Japanese abalone genome and population data, this study obtained some genetic characteristics of this species' adaptation to high-latitude environments. In terms of temperature adaptation, a series of cold-resistance-related genes in the Japanese abalone genome have specific changes compared with other species. For example, genes encoding antifreeze proteins show unique amplification in Japanese abalone. This type of protein can prevent the formation of tissue ice crystals at low temperatures and improve cell cold tolerance. Studies have shown that antifreeze active substances exist in the hemolymph of high-latitude abalone, and their genetic basis may be related to the expansion of antifreeze protein genes found in this study. The immune genome characteristics of Japanese abalone are also worth noting. Due to the disease stress in the aquaculture environment, breeding disease-resistant strains has become one of the main goals. This study compared the immune genes of Japanese abalone and other abalone and found that Japanese abalone has more types of immune-related genes, especially in some innate immune factors, such as pattern recognition receptors and lysozymes. For example, Japanese abalone has up to 29 TLR genes, which is currently the largest number in abalone (Zou et al., 2023). This may indicate that it is more sensitive and has more ways to identify pathogens. In the NF-κB signaling pathway, some immune regulatory genes of Japanese abalone, such as Rel, have some unique amino acid changes compared with other abalone. These changes may affect their ability to regulate immune responses (Sun et al., 2022). Through population genetic analysis, it can be seen that some gene loci related to disease resistance have undergone significant changes in the artificial breeding process of Japanese abalone. The frequency of some alleles has increased significantly, which may be deliberately retained by people during the breeding process. Most of these genes are related to the production of mucus and the enhancement of skin barrier function, which may help improve antibacterial ability. In terms of nutrition and metabolism, Japanese abalone also has its own characteristics. In order to adapt to the cold season, they may have developed a special way of energy storage. Their fat synthesis and decomposition related genes are expressed differently from warm water abalone. This may help them maintain basic body functions in the low temperatures of winter. From the phylogenetic analysis, Japanese abalone, Korean abalone and Japanese disc abalone actually belong to the same branch, and their genomes are very different. 5.2 Haliotis midae: genomic insights into warm-temperate tolerance African abalone, also known as South African abalone, is native to warm waters in southern Africa. Compared with Japanese abalone, African abalone has a stronger tolerance to high temperature environments, and its optimal growth temperature is significantly higher. In the context of global warming, African abalone has attracted attention as a high-temperature resistant variety. This study analyzed the adaptive characteristics of the African abalone genome. This study compared the protein-coding sequences of African abalone and Japanese abalone, and identified multiple genes that were positively selected in the African abalone branch. A considerable number of them are related to heat stress and protein homeostasis maintenance. For example, some members of the heat shock protein 70 (HSP70) family have specific amino acid substitutions in African abalone, which may enhance their folding aid function at high temperatures. For example, enzymes involved in antioxidant defense (such as superoxide dismutase SOD, peroxidase GPx, etc.) show higher copy numbers or gene expression potential in the African abalone genome, helping to clear high temperature-induced reactive oxygen damage (Shiel et al., 2015). Some metabolic genes in the African abalone genome have changed their regulatory sequences, allowing their metabolic rates to be maintained at high temperatures. For example, this study found that the promoter region of the mitochondrial respiratory chain complex protein gene of the African abalone has a unique cis-regulatory element, which may enhance the stability of its mitochondrial function under high temperature conditions. This is consistent with the observation that South African abalone can still maintain high vitality in the hot season (Tripp-Valdez et al., 2019). In terms of immunity, the pathogenic environment faced by African abalone is slightly different from that of temperate abalone, and its immune genome is also different accordingly. This study noted
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