The genomic basis of chiral variation and speciation in mirror-image snails

虽然我们的身体在外部是两侧对称的，但内部器官在其位置或解剖结构上表现出一致的、方向的不对称，因此左/右位置错误是人类出生缺陷的重要类别，在以后的生活中，许多疾病以偏侧的方式影响似乎对称的器官。然而，尽管不变的左/右不对称似乎是几乎所有动物的规律，但直到最近，人们还不清楚通往不对称的路径是否保守，或者左/右轴如何/为什么被一致地设置在同一方向(例如，心向左)。在BBSRC最近资助的研究(Current Biology 26：654-660)中，我们确定了决定池塘蜗牛镜像发育(手性)的Forin基因十亿分之一的碱基对变化，最终确定了第一个描述的逆转动物整个身体结构的基因位点。正如我们还表明，同样的基因也同样参与了青蛙的不对称性的建立，然后我们从蜗牛身上开始的研究最终揭示了整个比拉特里亚最早的共同对称破坏步骤之一。理解自然手性变异的一个关键问题是，池塘蜗牛是为数不多的致病突变是病理性的蜗牛物种之一-只有大约一半的后代存活下来。在其他种类的蜗牛中，例如日本的Euhadra，我们已经证明福尔明并不参与决定手性的变异，但我们不知道这些基因是什么，也不知道它们能够在没有相关病理的情况下引起手性变化的(几乎)不可思议的方法。该项目雄心勃勃的目标是确定Euhadra的手性位点，并了解它如何对可能的物种形成做出贡献。该项目很可能涉及一系列技术，从日本的田野调查到基因组学和生物信息学--平衡由学生的兴趣决定。

While our bodies are bilaterally symmetric on the outside, the internal organs exhibit consistent, directional asymmetries in their position or anatomy, such that left/right positional errors are an important class of human birth defect, and in later life, numerous diseases affect seemingly symmetric organs in a lateralised fashion. However, while invariant left/right asymmetry appears to be the rule in nearly all animals, until recently it has not been clear if the path to asymmetry is conserved, or how/why the left/right axis is consistently set up in the same direction (e.g. heart to the left). In recent BBSRC funded research (Current Biology 26: 654-660), we identified the one in a billion base pair change in a formin gene that determines mirror image development ("chirality") in the pond snail, finally identifying the first described locus that reverses the whole body structure of an animal. As we also showed that the same gene is similarly involved in setting up asymmetry in the frog, then our work that began in snails ultimately revealed one of the earliest common symmetry-breaking steps across the whole of the Bilateria. A key problem with respect to understanding natural chiral variation is that the pond snail is one of the few snail species in which the causative mutation is pathological - only about a half of the offspring survive. In other species of snail, such as Japanese Euhadra, we have shown that formin is not involved in determining variation in chirality, but we have no idea what the genes are, nor the (almost) inconceivable means by which they are able to cause a switch in chirality without associated pathology. It is the ambitious aim of this project to identify the chirality locus in Euhadra, and to understand how it contributes to possible speciation. The project will most likely involve a range of techniques, from fieldwork in Japan to genomics and bioinformatics - with the balance determined by the interests of the student.