大黄鱼ATG13基因序列分析及低温胁迫下多组织协同响应OA

Larimichthys crocea is an economically important warm-temperate marine aquaculture species native to China,and its limited low-temperature tolerance has long been recognized as a major bottleneck restricting the sustainable development of the industry.Autophagy serves as a central regulatory mechanism in cellular stress responses,yet the functional role of its key initiation gene ATG13 under cold stress in marine teleosts remains largely unclear.To systematically characterize the sequence features of L.crocea ATG13 and elucidate its multi-temporal and multi-tissue expression profiles under low-temperature stress,the full-length coding sequence(CDS)of LcATG13 was cloned in the present study,followed by comprehensive bioinformatic analyses of its structural properties,phylogenetic relationships,and predicted protein-protein interaction networks.Furthermore,six sequential temperature gradients(18℃,16℃,14℃,12℃,10℃,and 8℃)were established to simulate a gradual cold exposure process,and quantitative real-time PCR(qPCR)was performed to detect the mRNA expression patterns of LcATG13 across 10 representative tissues,including brain,gill,head kidney,trunk kidney,heart,spleen,liver,intestine,muscle,and skin.The results showed that the full-length CDS of LcATG13 was 1623 bp in length,encoding a deduced polypeptide of 540 amino acids.The deduced LcATG13 protein had a predicted molecular weight of 58.37 kDa and a theoretical isoelectric point of 4.90,and was identified as a nuclear-localized protein lacking a signal peptide and transmembrane domains.Phylogenetic analysis revealed that LcATG13 shared the highest sequence homology and clustered most closely with its ortholog from Morone saxatilis,indicating a high degree of evolutionary conservation across teleost species.Protein interaction prediction further demonstrated that LcATG13 could form a tight functional association with core autophagy regulators,including ULK1(ATG1),ULK2,and mTOR.Notably,low-temperature stress significantly induced the transcriptional activation of LcATG13 in a distinct tissue-specific and time-sequential manner:when temperature decreased from 18℃to 16℃,LcATG13 expression in the gill was rapidly upregulated by 2.65-fold;at 14℃,a sharp 7.86-fold increase was observed in the head kidney;at 12℃,the intestine exhibited the most prominent response with an 8.9-fold upregulation;at 10℃,the heart showed the strongest induction reaching 13.6-fold;and even at the extreme low temperature of 8℃,sustained high expression of LcATG13 was maintained in the skin.This study reveals a novel molecular regulatory pattern of multi-organ coordinated and temporally ordered response of the ATG13 gene in L.crocea under cold stress.These findings indicate that LcATG13,as a key upstream mediator of autophagy,participates in the cellular protective mechanism against low-temperature challenge in large yellow croaker,and its expression profile exhibits remarkable tissue-function specificity.The results not only provide new insights into the regulatory network underlying fish cold adaptation via the autophagy pathway,but also offer valuable candidate molecular targets for the breeding of cold-tolerant L.crocea strains and the optimization of overwintering aquaculture management strategies.