Study on Apoptosis of Various Tissues at Different Intervals after Death of Yangtze Sturgeon ( <i>Acipenser dabryanus</i> )

<b><i>Introduction:</i></b> The collection and preservation of postmortem genetic material from recently deceased animals of rare and endangered species represent a critical yet underexplored avenue in conservation biology. While extensive research has been conducted on the human postmortem interval (PMI), there is a notable gap in understanding the postmortem preservation of germplasm in endangered species. <b><i>Objectives:</i></b> This study aimed to investigate the dynamics of apoptosis in various tissues of the Yangtze sturgeon at different postmortem time points, and to provide a reference for identifying the optimal time window for germplasm preservation in rare and endangered fish in the wild. <b><i>Methods:</i></b> Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphated nick-end labeling assay and tissue morphology analyses were used to investigate apoptosis in the brain, heart, fin, liver, gonad, muscle, spleen, and skin of the Yangtze sturgeon at five different time points 0, 4, 8, 12, and 16 hours postmortem. <b><i>Results:</i></b> The results revealed a dynamic pattern of apoptosis. All tissues exhibited a time-dependent increase in apoptotic rate, indicating a clear correlation between PMI and apoptosis progression. This temporal pattern underscores the importance of timely genetic resource preservation, as the integrity of genetic material deteriorates progressively after death. Histomorphological analysis further demonstrated progressive degradation of tissue structure, especially in metabolically active tissues such as the gonad and fin. <b><i>Conclusion:</i></b> Based on the findings, we recommend that the genetic resources of the Yangtze sturgeon be preserved as soon as possible after death, particularly within the first 12 hours when tissue integrity remains sufficient for viable cell isolation or cryopreservation. This window is critical for metabolically active tissues, which show marked changes over time and may be important for postmortem identification. Further research should explore cryopreservation and antioxidant treatments to extend the preservation window for germplasm resources, ensuring the long-term viability of these valuable genetic materials.