Data from: Acute embryonic anoxia exposure favours the development of a dominant and aggressive phenotype in adult zebrafish

Eutrophication and climate change are increasing the incidence of severe hypoxia in fish nursery habitats, yet the programming effects of hypoxia on stress responsiveness in later life are poorly understood. In this study, to investigate whether early hypoxia alters the developmental trajectory of the stress response, zebrafish embryos were exposed to 4 h of anoxia at 36 h post-fertilization and reared to adults when the responses to secondary stressors were assessed. While embryonic anoxia did not affect basal cortisol levels or the cortisol response to hypoxia in later life, it had a marked effect on the responses to a social stressor. In dyadic social interactions, adults derived from embryonic anoxia initiated more chases, bit more often, entered fewer freezes and had lower cortisol levels. Adults derived from embryonic anoxia also performed more bites towards their mirror image, had lower gonadal aromatase gene expression and had higher testosterone levels. We conclude that acute embryonic anoxia has long-lasting consequences for the hormonal and behavioural responses to social interactions in zebrafish. Specifically, we demonstrate that acute embryonic anoxia favours the development of a dominant and aggressive phenotype, and that a disruption in sex steroid production may contribute to the programming effects of environmental hypoxia.

富营养化（Eutrophication）与气候变化正加剧鱼类育苗栖息地（fish nursery habitats）严重低氧（severe hypoxia）的发生频率，但目前学界对低氧的程序化效应（programming effects）如何影响机体后期生命阶段的应激反应性（stress responsiveness）仍知之甚少。本研究为探究早期低氧暴露是否会改变应激反应的发育轨迹，将斑马鱼胚胎（zebrafish embryos）于受精后36小时（36 h post-fertilization）置于无氧气（anoxia）环境中暴露4小时，并饲养至成体后评估其对继发性应激原（secondary stressors）的响应。尽管胚胎期无氧气暴露未影响成体的基础皮质醇水平（basal cortisol levels）或后期对低氧的皮质醇响应（cortisol response），但却对其面对社交应激原的响应产生了显著影响。在二元社交互动（dyadic social interactions）中，经胚胎期无氧气暴露处理的成体展现出更多的追逐行为、更高的咬击频率、更少的僵住行为，且皮质醇水平更低。此外，这类成体对镜像刺激的咬击次数更多，性腺芳香化酶基因表达（gonadal aromatase gene expression）水平更低，睾酮（testosterone）水平更高。本研究结论表明，急性胚胎期无氧气暴露会对斑马鱼社交互动中的激素与行为响应产生长期持久的影响。具体而言，本研究证实急性胚胎期无氧气暴露会促进优势攻击型表型（dominant and aggressive phenotype）的发育，而性类固醇生成（sex steroid production）紊乱可能参与介导环境低氧的程序化效应。