Tao Wang

In recent years, excessive human activities and climate deterioration have led to changes in the aquatic environment, causing frequent diseases in Takifugu fasciatus and huge economic losses. However, it is not clear whether the liver, an important immune organ for fish, can activate autophagy in response to stress caused by environmental changes (e.g., low temperature and Cu²⁺). Microtubule-associated proteins light chain 3 (lc3), beclin-1 and sequestosome 1 (p62) are important markers of mitochondrial autophagy. In this study, lc3, beclin-1 and p62 were cloned and analyzed for their molecular characteristics, homology and evolutionary relationships with other species using T. fasciatus as the study target. In addition, this experiment also studied the expression and distribution of lc3, beclin-1 and p62 genes in the brain, muscle, intestine, spleen, gill, heart, kidney and liver, and the expression levels in the liver under Cu²⁺ and a low-temperature environment. Cu²⁺ and water temperature were able to activate the mRNA and protein expression of lc3, beclin-1 and p62, and beclin-1 was more sensitive than lc3 and p62 in their livers in response to Cu²⁺ and the low-temperature environment. This study can help to elucidate the molecular mechanism of mitochondrial autophagy genes of T. fasciatus in response to Cu²⁺ and low-temperature environments, and provide a theoretical basis for guiding the culture of T. fasciatus.

Takifugu fasciatus is an aquaculture species with high economic value. In recent years, problems such as environmental pollution and inbreeding have caused a serious decline in T. fasciatus germplasm resources. In this study, a high-density genetic linkage map was constructed by whole-genome resequencing. The map consists of 4891 bin markers distributed across 22 linkage groups (LGs), with a total genetic coverage of 2381.353 cM and a mean density of 0.535 cM. Quantitative trait locus (QTL) localization analysis showed that a total of 19 QTLs associated with growth traits of T. fasciatus in the genome-wide significance threshold range, distributed on 11 LGs. In addition, 11 QTLs associated with cold tolerance traits were identified, each scattered on a different LG. Furthermore, we used QTL localization analysis to screen out three candidate genes (IGF1, IGF2, ADGRB) related to growth in T. fasciatus. Meanwhile, we screened three candidate genes (HSP90, HSP70, and HMGB1) related to T. fasciatus cold tolerance. Our study can provide a theoretical basis for the selection and breeding of cold-tolerant or fast-growing T. fasciatus.