Dissecting the Interaction Between the Genome and the Environment During Embryological Development in the Annual Killifish Austrofundulus limnaeus

胚胎发育的环境可以改变基因的活动，并导致持续整个有机体生命周期的发育变化。例如，在许多冷血动物(如许多种类的爬行动物和鱼类)中，个体的性别是由胚胎和幼体发育期间的温度敏感基因决定的。在一年生金枪鱼中，温度、氧气可获得性和光周期等环境因素对胚胎发育有深远的影响。这些鱼生活在热带沙漠地区的季节性小泥潭中，必须在没有水的情况下长时间存活。当水坑里有水的时候，成年鱼就会茁壮成长。然而，当池塘每年干涸时，成年鱼就会死亡，因为它们没有水就无法生存。该物种以耐旱胚胎的形式在旱季期间存活下来，进入一种被称为滞育的“暂停生命”状态。胚胎滞育的时间长短取决于发育过程中的环境条件。当环境条件较差(例如，温度低、日照时间短或缺水)时，一年生千里鱼的胚胎将长时间滞育，以便“等待”与旱季相关的恶劣条件。然而，当环境条件有利于成鱼的生存时(例如，温暖的温度和充足的水)，胚胎可能只停留在很短的一段时间内滞育，或者可能一起跳过滞育。这项提案中概述的研究旨在了解环境线索如何改变一年生七条鱼的发育模式，以包括或排除滞育期的休眠期。一年生青鱼进入或退出滞育很可能是由特定基因的作用引起的。这项研究将使用微阵列或“基因芯片”技术来鉴定这些基因。一年一度的千里鱼“基因芯片”将包含很大比例的一年一次的千里鱼基因，并将被用作筛选工具，以确定哪些基因与一年一年的千里鱼进入和退出滞育有关。对这些基因的识别是了解环境线索如何改变一年生千里鱼的发育程序的第一步。

The environment in which an embryo develops can alter the activity of genes and cause developmental changes that last throughout the organism's life span. For example, in many cold-blooded animals (e.g., many species of reptiles and fish) the sex of an individual is determined by temperature-sensitive genes during embryonic and larval development. In the annual killifish Austrofundulus limnaeus, environmental factors including temperature, oxygen availability, and photoperiod have profound effects on embryonic development. These fish live in small seasonal mud puddles in tropical desert regions and must survive for long periods of time without water. When water is present in the puddles, the adult fish thrive. However, when the ponds dry each year, the adult fish die because they can not survive without water. The species survives the duration of the dry season in the form of drought-tolerant embryos that enter a state of "suspended animation" termed diapause. The amount of time that an embryo spends in diapause is dependent on environmental conditions during development. When environmental conditions are poor (e.g., low temperatures, short day lengths, or lack of water) embryos of annual killifish remain in diapause for long periods of time in order to "wait out" the harsh conditions associated with the dry season. However, when environmental conditions are favorable for survival of adult fish (e.g., warm temperatures, and abundant water) the embryos may stay in diapause for only a short period of time, or may skip diapause all together. The research outlined in this proposal is aimed at understanding how environmental cues can alter the developmental pattern of annual killifish to either include or exclude a period of dormancy in diapause. Entry or exit from diapause in annual killifish is likely caused by the action of specific genes. This research will use microarray or "gene chip" technology to identify these genes. The annual killifish "gene chip" will contain a large percentage of the annual killifish genes and will be used as a screening tool to identify which genes are associated with entry into and exit from diapause in annual killifish. The identification of these genes is the first step towards understanding how environmental cues can alter the developmental program of annual killifish.