Li Ning, Flanagan Ben A, Partridge MacKenzie, Huang Elaine J, Edmands Suzanne
Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA, 90089, USA.
BMC Genomics. 2020 Nov 3;21(1):759. doi: 10.1186/s12864-020-07179-5.
Patterns of gene expression can be dramatically different between males and females of the same species, in part due to genes on sex chromosomes. Here we test for sex differences in early transcriptomic response to oxidative stress in a species which lacks heteromorphic sex chromosomes, the copepod Tigriopus californicus.
Male and female individuals were separately exposed to control conditions and pro-oxidant conditions (hydrogen peroxide and paraquat) for periods of 3 hours and 6 hours. Variance partitioning showed the greatest expression variance among individuals, highlighting the important information that can be obscured by the common practice of pooling individuals. Gene expression variance between sexes was greater than that among treatments, showing the profound effect of sex even when males and females share the same genome. Males exhibited a larger response to both pro-oxidants, differentially expressing more than four times as many genes, including up-regulation of more antioxidant genes, heat shock proteins and protease genes. While females differentially expressed fewer genes, the magnitudes of fold change were generally greater, indicating a more targeted response. Although females shared a smaller fraction of differentially expressed genes between stressors and time points, expression patterns of antioxidant and protease genes were more similar between stressors and more GO terms were shared between time points.
Early transcriptomic responses to the pro-oxidants HO and paraquat in copepods revealed substantial variation among individuals and between sexes. The finding of such profound sex differences in oxidative stress response, even in the absence of sex chromosomes, highlights the importance of studying both sexes and the potential for developing sex-specific strategies to promote optimal health and aging in humans.
同一物种的雄性和雌性之间的基因表达模式可能存在显著差异，部分原因是性染色体上的基因。在此，我们对一种缺乏异形性染色体的物种——桡足类动物加州虎斑猛水蚤，早期转录组对氧化应激的反应中的性别差异进行了测试。
将雄性和雌性个体分别置于对照条件和促氧化剂条件（过氧化氢和百草枯）下处理3小时和6小时。方差分解显示个体间的表达差异最大，这突出了合并个体这一常见做法可能会掩盖的重要信息。性别之间的基因表达差异大于处理之间的差异，这表明即使雄性和雌性共享相同的基因组，性别仍具有深远影响。雄性对两种促氧化剂的反应更大，差异表达的基因数量是雌性的四倍多，包括更多抗氧化基因、热休克蛋白和蛋白酶基因的上调。虽然雌性差异表达的基因较少，但倍数变化的幅度通常更大，表明其反应更具针对性。尽管雌性在应激源和时间点之间共享的差异表达基因比例较小，但应激源之间抗氧化剂和蛋白酶基因的表达模式更相似，时间点之间共享的基因本体论（GO）术语更多。
桡足类动物对促氧化剂过氧化氢和百草枯的早期转录组反应揭示了个体间和性别间的显著差异。即使在没有性染色体的情况下，氧化应激反应中存在如此显著的性别差异这一发现，凸显了对两性进行研究的重要性，以及开发针对性别的策略以促进人类最佳健康和衰老的潜力。
