Wong Ryan Y, McLeod Melissa M, Godwin John
Department of Biological Sciences, W,M, Keck Center for Behavioral Biology, Box 7617, North Carolina State University, Raleigh, NC 27695-7617, USA.
BMC Genomics. 2014 Oct 17;15(1):905. doi: 10.1186/1471-2164-15-905.
Male and female vertebrates typically differ in a range of characteristics, from morphology to physiology to behavior, which are influenced by factors such as the social environment and the internal hormonal and genetic milieu. However, sex differences in gene expression profiles in the brains of vertebrates are only beginning to be understood. Fishes provide a unique complement to studies of sex differences in mammals and birds given that fish show extreme plasticity and lability of sexually dimorphic characters and behaviors during development and even adulthood. Hence, teleost models can give additional insight into sexual differentiation. The goal of this study is to identify neurotranscriptomic mechanisms for sex differences in the brain.
In this study we examined whole-brain sex-biased gene expression through RNA-sequencing across four strains of zebrafish. We subsequently conducted systems level analyses by examining gene network dynamics between the sexes using weighted gene coexpression network analysis. Surprisingly, only 61 genes (approximately 0.4% of genes analyzed) showed a significant sex effect across all four strains, and 48 of these differences were male-biased. Several of these genes are associated with steroid hormone biosynthesis. Despite sex differences in a display of stress-related behaviors, basal transcript levels did not predict the intensity of the behavioral display. WGCNA revealed only one module that was significantly associated with sex. Intriguingly, comparing intermodule dynamics between the sexes revealed only moderate preservation. Further we identify sex-specific gene modules.
Despite differences in morphology, physiology, and behavior, there is limited sex-biased neural gene expression in zebrafish. Further, genes found to be sex-biased are associated with hormone biosynthesis, suggesting that sex steroid hormones may be key contributors to sexual behavioral plasticity seen in teleosts. A possible mechanism is through regulating specific brain gene networks.
雄性和雌性脊椎动物通常在一系列特征上存在差异，从形态学到生理学再到行为学，这些差异受到社会环境以及体内激素和基因环境等因素的影响。然而，脊椎动物大脑中基因表达谱的性别差异才刚刚开始被了解。鉴于鱼类在发育甚至成年期的性二态特征和行为表现出极大的可塑性和易变性，鱼类为研究哺乳动物和鸟类的性别差异提供了独特的补充。因此，硬骨鱼模型可以为性别分化提供更多见解。本研究的目的是确定大脑中性别差异的神经转录组学机制。
在本研究中，我们通过对四种斑马鱼品系进行RNA测序，检测了全脑性别偏向性基因表达。随后，我们使用加权基因共表达网络分析来研究性别之间的基因网络动态，进行系统水平分析。令人惊讶的是，在所有四个品系中，只有61个基因（约占分析基因的0.4%）显示出显著的性别效应，其中48个差异为雄性偏向。这些基因中有几个与类固醇激素生物合成相关。尽管在应激相关行为表现上存在性别差异，但基础转录水平并不能预测行为表现的强度。WGCNA仅揭示了一个与性别显著相关的模块。有趣的是，比较性别之间的模块间动态仅发现了适度的保守性。此外，我们确定了性别特异性基因模块。
尽管在形态学、生理学和行为上存在差异，但斑马鱼中性别偏向性神经基因表达有限。此外，发现具有性别偏向性的基因与激素生物合成相关，这表明性类固醇激素可能是硬骨鱼中所见性行为可塑性的关键因素。一种可能的机制是通过调节特定的脑基因网络。
