Ark shells are commercially important clam species that inhabit in muddy sediments of shallow coasts in East Asia. For a long time, the lack of genome resources has hindered scientific research of ark shells. Here, we report a high-quality chromosome-level genome assembly of Scapharca kagoshimensis, with an aim to unravel the molecular basis of heme biosynthesis, and develop genomic resources for genetic breeding and population genetics in ark shells. Nineteen scaffolds corresponding to 19 chromosomes were constructed from 938 contigs (contig N50 = 2.01 Mb) to produce a final high-quality assembly with a total length of 1.11 Gb and scaffold N50 around 60.64 Mb. The genome assembly represents 93.4% completeness via matching 303 eukaryota core conserved genes. A total of 24,908 protein-coding genes were predicted and 24,551 genes (98.56%) of which were functionally annotated. The enrichment analyses suggested that genes in heme biosynthesis pathways were expanded and positive selection of the haemoglobin genes was also found in the genome of S. kagoshimensis, which gives important insights into the molecular mechanisms and evolution of the heme biosynthesis in mollusca. The valuable genome assembly of S. kagoshimensis would provide a solid foundation for investigating the molecular mechanisms that underlie the diverse biological functions and evolutionary adaptations of S. kagoshimensis.

中文翻译：

---

Scapharca kagoshimensis 的染色体水平基因组组装揭示了方舟壳中血红素生物合成的扩展分子基础

方舟贝是商业上重要的蛤类物种，栖息在东亚浅海岸的泥泞沉积物中。长期以来，基因组资源的缺乏阻碍了方舟贝壳的科学研究。在这里，我们报告了Scapharca kagoshimensis的高质量染色体水平基因组组装，旨在解开血红素生物合成的分子基础，并开发用于方舟贝壳遗传育种和种群遗传学的基因组资源。对应于 19 条染色体的 19 个支架由 938 个重叠群（重叠群 N50 = 2.01 Mb）构建，以产生总长度为 1.11 Gb 和支架 N50 约 60.64 Mb 的最终高质量组装。通过匹配 303 个真核核心保守基因，基因组组装代表 93.4% 的完整性。共预测了 24,908 个蛋白质编码基因，其中 24,551 个基因（98.56%）进行了功能注释。富集分析表明血红素生物合成途径中的基因被扩展，并且在鹿儿岛血红素基因组中也发现了血红蛋白基因的正选择，这为软体动物血红素生物合成的分子机制和进化提供了重要的见解。S的宝贵基因组组装。 kagoshimensis将为研究S . . kagoshimensis。