Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA 90089, USA.
Comp Biochem Physiol Part D Genomics Proteomics. 2019 Sep;31:100608. doi: 10.1016/j.cbd.2019.100608. Epub 2019 Jul 11.
Oxidative stress reflects the imbalance of pro-oxidants and antioxidants. Prolonged oxidative stress can induce cellular damage, diseases and aging, and the effects may be sex-specific. Tigriopus californicus has recently been proposed as an alternative model system for sex-specific studies due to the absence of sex chromosomes. In this study, we used comparative transcriptomic analyses to assess sex-specific transcriptional responses to oxidative stress. Male and female individuals were maintained separately in one of three treatments: 1) control conditions with an algae diet, 2) pro-oxidant (HO) conditions with an algae diet or 3) decreased antioxidant conditions (reduced carotenoids due to a yeast diet). Single individual RNA-seq was then conducted for twenty-four libraries using Ligation Mediated RNA sequencing (LM-Seq). Variance in gene expression was partitioned into 62.3% between sexes, 26.85% among individuals and 10.85% among treatments. Within each of the three treatments, expression was biased toward females. However, compared to the control treatment, males in both pro-oxidant and decreased antioxidant treatments differentially expressed more genes while females differentially expressed fewer genes but with a greater magnitude of fold change. As the first study of copepods to apply single individual RNA-seq, the findings will contribute to a better understanding of transcriptomic variation among individuals as well as sex-specific response mechanisms to oxidative stress in the absence of sex chromosomes.
氧化应激反映了氧化剂和抗氧化剂之间的不平衡。长期的氧化应激会导致细胞损伤、疾病和衰老，其影响可能具有性别特异性。加利福尼亚水蚤由于没有性染色体，最近被提议作为性别特异性研究的替代模型系统。在这项研究中，我们使用比较转录组分析来评估氧化应激对性别特异性转录反应的影响。雄性和雌性个体分别在三种处理方式下单独饲养：1）含藻类的对照条件，2）含藻类的促氧化剂（HO）条件，或 3）含酵母的抗氧化剂减少条件（由于酵母饮食导致类胡萝卜素减少）。然后，使用连接介导的 RNA 测序（LM-Seq）对二十四个文库中的二十四个个体进行了单独的 RNA-seq。基因表达的方差分为 62.3%的性别差异、26.85%的个体差异和 10.85%的处理差异。在三种处理方式中，表达都偏向于雌性。然而，与对照处理相比，在促氧化剂和抗氧化剂减少处理中，雄性个体差异表达的基因更多，而雌性个体差异表达的基因更少，但倍数变化的幅度更大。作为第一项应用单个体 RNA-seq 的桡足类动物研究，这些发现将有助于更好地理解个体之间的转录组变异，以及在没有性染色体的情况下，氧化应激对性别特异性反应机制。
