Copepods encompass numerous ecological roles including parasites, detrivores and phytoplankton grazers. Nonetheless, copepod genome assemblies remain scarce. Lepeophtheirus salmonis is an economically and ecologically important ectoparasitic copepod found on salmonid fish. We present the 695.4 Mbp L. salmonis genome assembly containing ≈60% repetitive regions and 13,081 annotated protein-coding genes. The genome comprises 14 autosomes and a ZZ-ZW sex chromosome system. Assembly assessment identified 92.4% of the expected arthropod genes. Transcriptomics supported annotation and indicated a marked shift in gene expression after host attachment, including apparent downregulation of genes related to circadian rhythm coinciding with abandoning diurnal migration. The genome shows evolutionary signatures including loss of genes needed for peroxisome biogenesis, presence of numerous FNII domains, and an incomplete heme homeostasis pathway suggesting heme proteins to be obtained from the host. Despite repeated development of resistance against chemical treatments L. salmonis exhibits low numbers of many genes involved in detoxification.

桡足类包含许多生态角色，包括寄生虫、食肉动物和浮游植物食草动物。尽管如此，桡足类基因组组装仍然稀缺。Lepeophtheirus Salmonis是一种在鲑鱼身上发现的具有重要经济和生态意义的外寄生桡足类动物。我们展示了 695.4 Mbp 的鲑鱼乳杆菌基因组组装包含约 60% 的重复区域和 13,081 个带注释的蛋白质编码基因。基因组包括 14 个常染色体和一个 ZZ-ZW 性染色体系统。组装评估确定了 92.4% 的预期节肢动物基因。转录组学支持注释并表明宿主附着后基因表达的显着转变，包括与昼夜节律相关的基因明显下调与放弃昼夜迁移相吻合。基因组显示出进化特征，包括过氧化物酶体生物发生所需基因的丢失、大量 FNII 结构域的存在以及不完整的血红素稳态途径，表明血红素蛋白应从宿主中获得。尽管对化学处理的抗性不断发展，但鲑鱼乳杆菌与解毒有关的许多基因数量很少。