Jiangsu Key Laboratory for Bioaffiliationersity and Biotechnology, College of Life Sciences, Nanjing Normal University, 210023, Nanjing, China.
BMC Genomics. 2024 Apr 4;25(1):339. doi: 10.1186/s12864-024-10263-9.
Cetaceans, having experienced prolonged adaptation to aquatic environments, have undergone evolutionary changes in their respiratory systems. This process of evolution has resulted in the emergence of distinctive phenotypic traits, notably the abundance of elastic fibers and thickened alveolar walls in their lungs, which may facilitate alveolar collapse during diving. This structure helps selective exchange of oxygen and carbon dioxide, while minimizing nitrogen exchange, thereby reducing the risk of DCS. Nevertheless, the scientific inquiry into the mechanisms through which these unique phenotypic characteristics govern the diving behavior of marine mammals, including cetaceans, remains unresolved.
This study entails an evolutionary analysis of 42 genes associated with pulmonary fibrosis across 45 mammalian species. Twenty-one genes in cetaceans exhibited accelerated evolution, featuring specific amino acid substitutions in 14 of them. Primarily linked to the development of the respiratory system and lung morphological construction, these genes play a crucial role. Moreover, among marine mammals, we identified eight genes undergoing positive selection, and the evolutionary rates of three genes significantly correlated with diving depth. Specifically, the SFTPC gene exhibited convergent amino acid substitutions. Through in vitro cellular experiments, we illustrated that convergent amino acid site mutations in SFTPC contribute positively to pulmonary fibrosis in marine mammals, and the presence of this phenotype can induce deep alveolar collapse during diving, thereby reducing the risk of DCS during diving.
The study unveils pivotal genetic signals in cetaceans and other marine mammals, arising through evolution. These genetic signals may influence lung characteristics in marine mammals and have been linked to a reduced risk of developing DCS. Moreover, the research serves as a valuable reference for delving deeper into human diving physiology.
鲸目动物经历了漫长的水生环境适应，其呼吸系统发生了进化变化。这一进化过程导致了独特表型特征的出现，特别是肺部弹性纤维的丰富和肺泡壁的增厚，这可能有助于潜水时肺泡的塌陷。这种结构有助于氧气和二氧化碳的选择性交换，同时最大限度地减少氮气交换，从而降低减压病的风险。然而，对于这些独特的表型特征如何控制海洋哺乳动物（包括鲸目动物）的潜水行为的机制的科学研究仍未解决。
本研究对 45 种哺乳动物的 42 个与肺纤维化相关的基因进行了进化分析。鲸目中有 21 个基因表现出加速进化，其中 14 个基因具有特定的氨基酸取代。这些基因主要与呼吸系统的发育和肺形态结构有关，起着关键作用。此外，在海洋哺乳动物中，我们确定了 8 个经历正选择的基因，其中 3 个基因的进化速率与潜水深度显著相关。具体来说，SFTPC 基因经历了正选择。通过体外细胞实验，我们表明 SFTPC 中的趋同氨基酸取代突变对海洋哺乳动物的肺纤维化有积极作用，并且这种表型的存在可以诱导潜水时肺泡的深度塌陷，从而降低潜水时减压病的风险。
本研究揭示了鲸目动物和其他海洋哺乳动物进化过程中关键的遗传信号。这些遗传信号可能影响海洋哺乳动物的肺部特征，并与降低减压病风险有关。此外，该研究为深入研究人类潜水生理学提供了有价值的参考。
