Hale Matthew C, McKinney Garrett J, Thrower Frank P, Nichols Krista M
Department of Biological Sciences, Purdue University, West State Street, West Lafayette, Indiana, United States of America.
Department of Biology, Texas Christian University, Fort Worth, Texas, United States of America.
PLoS One. 2018 Feb 15;13(2):e0193009. doi: 10.1371/journal.pone.0193009. eCollection 2018.
Sex-bias in gene expression is a mechanism that can generate phenotypic variance between the sexes, however, relatively little is known about how patterns of sex-bias vary during development, and how variable sex-bias is between different populations. To that end, we measured sex-bias in gene expression in the brain transcriptome of rainbow trout (Oncorhynchus mykiss) during the first two years of development. Our sampling included from the fry stage through to when O. mykiss either migrate to the ocean or remain resident and undergo sexual maturation. Samples came from two F1 lines: One from migratory steelhead trout and one from resident rainbow trout. All samples were reared in a common garden environment and RNA sequencing (RNA-seq) was used to estimate patterns of gene expression. A total of 1,716 (4.6% of total) genes showed evidence of sex-bias in gene expression in at least one time point. The majority (96.7%) of sex-biased genes were differentially expressed during the second year of development, indicating that patterns of sex-bias in expression are tied to key developmental events, such as migration and sexual maturation. Mapping of differentially expressed genes to the O. mykiss genome revealed that the X chromosome is enriched for female upregulated genes, and this may indicate a lack of dosage compensation in rainbow trout. There were many more sex-biased genes in the migratory line than the resident line suggesting differences in patterns of gene expression in the brain between populations subjected to different forces of selection. Overall, our results suggest that there is considerable variation in the extent and identity of genes exhibiting sex-bias during the first two years of life. These differentially expressed genes may be connected to developmental differences between the sexes, and/or between adopting a resident or migratory life history.
基因表达中的性别偏差是一种可导致两性之间表型差异的机制，然而，对于性别偏差模式在发育过程中如何变化，以及不同种群之间的性别偏差差异有多大，我们了解得相对较少。为此，我们测量了虹鳟（Oncorhynchus mykiss）发育头两年大脑转录组中的基因表达性别偏差。我们的采样涵盖了从鱼苗阶段到虹鳟要么洄游到海洋，要么留在原地并经历性成熟的时期。样本来自两个F1品系：一个来自洄游的虹鳟，另一个来自定居的虹鳟。所有样本都在共同的养殖环境中饲养，并使用RNA测序（RNA-seq）来估计基因表达模式。共有1716个基因（占总数的4.6%）在至少一个时间点显示出基因表达的性别偏差证据。大多数（96.7%）性别偏差基因在发育的第二年差异表达，这表明表达中的性别偏差模式与关键发育事件相关，如洄游和性成熟。将差异表达基因映射到虹鳟基因组表明，X染色体富含雌性上调基因，这可能表明虹鳟缺乏剂量补偿。洄游品系中的性别偏差基因比定居品系中的多得多，这表明在受到不同选择压力的种群之间，大脑中的基因表达模式存在差异。总体而言，我们的结果表明，在生命的头两年中，表现出性别偏差的基因的程度和特性存在相当大的差异。这些差异表达基因可能与两性之间的发育差异和/或与采用定居或洄游生活史之间的差异有关。
