Department of Biology, University of Maryland.
Department of Biology, University of Maryland;
J Vis Exp. 2021 Feb 14(168). doi: 10.3791/61708.
The Mexican tetra, Astyanax mexicanus, is an emerging model system for studies in development and evolution. The existence of eyed surface (surface fish) and blind cave (cave fish) morphs in this species presents an opportunity to interrogate the mechanisms underlying morphological and behavioral evolution. Cave fish have evolved novel constructive and regressive traits. The constructive changes include increases in taste buds and jaws, lateral line sensory organs, and body fat. The regressive changes include loss or reduction of eyes. melanin pigmentation, schooling behavior, aggression, and sleep. To experimentally interrogate these changes, it is crucial to obtain large numbers of spawned embryos. Since the original A. mexicanus surface fish and cave fish were collected in Texas and Mexico in the 1990s, their descendants have been routinely stimulated to breed and spawn large numbers of embryos bimonthly in the Jeffery laboratory. Although breeding is controlled by food abundance and quality, light-dark cycles, and temperature, we have found that incremental temperature changes play a key role in stimulating maximal spawning. The gradual increase of temperature from 72 °F to 78 °F in the first three days of a breeding week provides two-three consecutive spawning days with maximal numbers of high-quality embryos, which is then followed by a gradual decrease of temperature from 78 °F to 72 °F during the last three days of the spawning week. The procedures shown in this video outline the workflow before and during a laboratory breeding week for incremental temperature stimulated spawning.
墨西哥脂鲤（Astyanax mexicanus）是一种新兴的发育和进化研究模式生物。该物种具有眼斑（表型鱼）和盲眼（洞穴鱼）两种表型，为研究形态和行为进化的机制提供了机会。洞穴鱼进化出了新的构造和退化特征。构造性变化包括味蕾和下颚、侧线感觉器官和体脂的增加。退化性变化包括眼睛、黑色素沉着、群体行为、攻击性和睡眠的丧失或减少。为了对这些变化进行实验性研究，获得大量产卵胚胎至关重要。由于最初的 A. mexicanus 表型鱼和洞穴鱼于 20 世纪 90 年代在德克萨斯州和墨西哥被采集，它们的后代已经在杰弗里实验室中定期被刺激繁殖并产卵，以每月两次的频率产生大量胚胎。尽管繁殖受到食物丰度和质量、光暗周期和温度的控制，但我们发现温度的逐渐升高在刺激最大产卵方面起着关键作用。在繁殖周的前三天，温度从 72 °F 逐渐升高到 78 °F，这提供了两到三天的连续产卵期，产生大量高质量的胚胎，然后在产卵周的最后三天，温度从 78 °F 逐渐降低到 72 °F。本视频中展示的程序概述了实验室繁殖周前和期间的工作流程，包括递增温度刺激产卵。
