Department of Biological Sciences, SLRC-Sea Lice Research Centre, University of Bergen, Bergen, Norway.
PLoS One. 2022 Mar 31;17(3):e0266022. doi: 10.1371/journal.pone.0266022. eCollection 2022.
Salmon lice are ectoparasites on salmonids and feed on blood, mucus, and skin from their hosts. This causes high annual costs for treatment and control for the aquaculture industry. Salmon lice have a life cycle consisting of eight life stages. Sex determination by eye is only possible from the sixth stage onwards. A molecular sex determination has not been carried out so far, even though few individual sex-linked SNPs have been reported. In the present study, we used known sex-specific SNPs as a basis to sequence the complete sex-specific gene variants and used the sequence information to develop a sex determination assay. This assay could be used to determine the developmental speed of the two sexes already in the earliest life stages. Additionally, we sampled salmon lice in the nauplius II stage, determined the sex of each individual, pooled their RNA according to their sex, and used RNA sequencing to search for differences in gene expression and further sex-specific SNPs. We succeeded in developing a sex-determination assay that works on DNA or RNA from even the earliest larval stages of the salmon louse after hatching. At these early developmental stages, male salmon lice develop slightly quicker than females. We detected several previously unknown, sex-specific SNPs in our RNA-data seq, but only very few genes showed a differential expression between the sexes. Potential connections between SNPs, gene expression, and development are discussed.
鲑虱是鲑鱼的外寄生虫，以宿主的血液、黏液和皮肤为食。这给水产养殖业每年的治疗和控制带来了高昂的成本。鲑虱的生命周期包括八个生命阶段。通过眼睛进行性别鉴定只能从第六个阶段开始。到目前为止，还没有进行分子性别鉴定，尽管已经报道了少数个体性连锁单核苷酸多态性。在本研究中，我们使用已知的性别特异性单核苷酸多态性作为基础，对完整的性别特异性基因变异进行测序，并利用序列信息开发性别鉴定检测方法。该检测方法可用于确定两性在最早的生命阶段的发育速度。此外，我们在桡足幼体 II 期采集鲑虱样本，确定每个个体的性别，根据其性别混合它们的 RNA，并使用 RNA 测序来寻找基因表达差异和进一步的性别特异性单核苷酸多态性。我们成功地开发了一种性别鉴定检测方法，可以在鲑虱孵化后的最早幼虫阶段的 DNA 或 RNA 上进行检测。在这些早期发育阶段，雄性鲑虱的发育速度比雌性稍快。我们在 RNA 数据测序中检测到了几个以前未知的、性别特异性的单核苷酸多态性，但只有极少数基因在两性之间表现出差异表达。讨论了单核苷酸多态性、基因表达和发育之间的潜在联系。
