Phenotypic responses to the environment may be controlled via cytosine methylation (5mC) and its effects on gene expression. We test whether hypoxia influences plastic or heritable changes in the quantity of 5mC in the genomes of a widespread African cichlid, the Egyptian mouth-brooder, Pseudocrenilabrus multicolor (Schöller, 1903). Fish were collected from three sites in southwestern Uganda: one hypoxic swamp, one swamp-river ecotonal area, and one well-oxygenated river site. F 1 offspring were raised in a split-brood experiment under both high- (normoxic) and low-oxygen (hypoxic) conditions. Previous work on morphological and physiological variation that stemmed from this experiment showed that the majority of responses to hypoxia were plastic, with some genetic variation in plasticity observed among populations. To partition evolutionary and plastic effects on 5mC, we estimated the percentage of methylated cytosines in the genomes of the muscle, gills, and brain. Our results showed that the quantity of 5mC varied among tissues, and there were significant differences between rearing treatments for the gills in families from the swamp site, with higher cytosine methylation levels under hypoxic laboratory conditions. No other significant differences were observed, but more extensive sampling schemes, as well as contrasting genomic 5mC patterns to transcriptional variation, could shed additional light on the molecular basis of plasticity in response to hypoxia.

中文翻译：

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量化响应非洲慈鲷鱼鳃、肌肉和大脑缺氧的全基因组胞嘧啶甲基化

对环境的表型反应可以通过胞嘧啶甲基化 (5mC) 及其对基因表达的影响来控制。我们测试了缺氧是否会影响广泛分布的非洲慈鲷、埃及口育鱼、多色 Pseudocrenilabrus 基因组中 5mC 数量的可塑性或可遗传变化（Schöller，1903）。从乌干达西南部的三个地点收集鱼：一个缺氧沼泽，一个沼泽河流生态区和一个充氧良好的河流地点。F 1 后代在高氧（常氧）和低氧（缺氧）条件下在分裂育雏实验中饲养。源于该实验的形态学和生理学变异的先前研究表明，对缺氧的大多数反应是可塑性的，在种群中观察到一些可塑性的遗传变异。为了区分对 5mC 的进化和可塑性影响，我们估计了肌肉、鳃和大脑基因组中甲基化胞嘧啶的百分比。我们的结果表明，5mC 的数量因组织而异，沼泽地家庭鳃的饲养处理之间存在显着差异，在实验室缺氧条件下胞嘧啶甲基化水平较高。没有观察到其他显着差异，但更广泛的采样方案，以及将基因组 5mC 模式与转录变异进行对比，可以进一步阐明响应缺氧的可塑性的分子基础。沼泽地家庭的鳃在饲养处理之间存在显着差异，在实验室缺氧条件下胞嘧啶甲基化水平较高。没有观察到其他显着差异，但更广泛的采样方案，以及将基因组 5mC 模式与转录变异进行对比，可以进一步阐明响应缺氧的可塑性的分子基础。沼泽地家族的鳃在饲养处理之间存在显着差异，在实验室缺氧条件下胞嘧啶甲基化水平较高。没有观察到其他显着差异，但更广泛的采样方案，以及将基因组 5mC 模式与转录变异进行对比，可以进一步阐明响应缺氧的可塑性的分子基础。