Integrative Science Center of Germplasm Creation in Western China (Chongqing) Science City, MOE Key Laboratory of Freshwater Fish Reproduction and Development, School of Life Sciences, Southwest University, Chongqing 400715, China.
State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China.
Cell Genom. 2024 Aug 14;4(8):100607. doi: 10.1016/j.xgen.2024.100607. Epub 2024 Jul 11.
Chondrichthyes is an important lineage to reconstruct the evolutionary history of vertebrates. Here, we analyzed genome synteny for six chondrichthyan chromosome-level genomes. Our comparative analysis reveals a slow evolutionary rate of chromosomal changes, with infrequent but independent fusions observed in sharks, skates, and chimaeras. The chondrichthyan common ancestor had a proto-vertebrate-like karyotype, including the presence of 18 microchromosome pairs. The X chromosome is a conversed microchromosome shared by all sharks, suggesting a likely common origin of the sex chromosome at least 181 million years ago. We characterized the Y chromosomes of two sharks that are highly differentiated from the X except for a small young evolutionary stratum and a small pseudoautosomal region. We found that shark sex chromosomes lack global dosage compensation but that dosage-sensitive genes are locally compensated. Our study on shark chromosome evolution enhances our understanding of shark sex chromosomes and vertebrate chromosome evolution.
软骨鱼是重建脊椎动物进化历史的重要谱系。在这里，我们分析了六种软骨鱼染色体水平基因组的基因组同线性。我们的比较分析揭示了染色体变化的缓慢进化率，在鲨鱼、鳐鱼和嵌合体中观察到了不频繁但独立的融合。软骨鱼的共同祖先具有类似于原脊椎动物的核型，包括存在 18 对微染色体。X 染色体是所有鲨鱼共有的保守微染色体，这表明性染色体至少在 1.81 亿年前就有了共同的起源。我们对两条鲨鱼的 Y 染色体进行了特征描述，它们与 X 染色体高度分化，除了一小部分年轻的进化层和一小部分假常染色体区域外。我们发现鲨鱼的性染色体没有全局剂量补偿，但剂量敏感基因在局部得到了补偿。我们对鲨鱼染色体进化的研究增强了我们对鲨鱼性染色体和脊椎动物染色体进化的理解。
