Investigations of Mouse Interspecies Hybrids

描述（由申请人提供）：种间杂种具有一系列与进化分离大致相关的异常表型，其范围从胚胎基因组激活失败/早期植入前致死到雄性不育的生存力。近年来，人们发现小分子沉默RNA在卵母细胞和雄性生殖细胞的胚胎发育和配子发生中起着重要作用。这些RNA被认为提供的作用之一是控制转座因子（TE），转座因子在人类和小鼠基因组中占很大比例。然而，有证据表明，这些调节RNA在调节宿主基因和基因组的表观遗传修饰中也是重要的。这种理解的一个结果是将种间杂种视为在调节RNA和父本基因组之间缺乏足够的同源性，这然后可以导致异常杂种发育不全表型的谱。在这个提议中，我们希望通过恢复父核区室和卵母细胞胞质区室之间更大程度的同源性来测试这种可能性，包括通过创建第一个“真正的”种间杂交体来存储调节小分子。真正的杂种将拥有来自两个亲本物种的相等或接近相等的细胞核和细胞质。我们选择使用小家鼠：卡罗里或spretus杂种，并评估它们的生存能力，雄性不育和体细胞生长/肥胖。如果成功的话，这种方法可以用来描述其他种间杂种的特征。这些实验为进一步了解受精后的早期事件如何编程合子基因组奠定了基础，因此将为表观遗传基因调控，转座子调控，动物克隆中体细胞核的重编程以及进化/物种形成提供信息。 RNA沉默系统的发现极大地改变了我们对基因调控的理解。这一点在生殖细胞系和早期胚胎中最为重要。种间杂交提供了一种工具，以了解基因通常是如何表观遗传修饰和编程整个发展。这个项目的目的是确定是否可以通过增加卵母细胞细胞质和合子原核之间的同源性来减少种间杂种中的异常（杂种发育不全）。

DESCRIPTION (provided by applicant): Interspecific hybrids have a spectrum of abnormal phenotypes roughly correlating with evolutionary separation which range from failure of embryonic genome activation /early preimplantation lethality to viability with male sterility. Recently the importance's of small silencing RNA's have been found to play a critical role in the oocyte and male germline for embryo development and gametogenesis. One of the roles these RNA's are thought to provide is the control of transposable elements (TE) which represent a significant percentage of the human and mouse genomes. However evidence exists that these regulatory RNA's are also important in regulating host genes and epigenetic modifications of the genome. One consequence of this understanding is to view interspecies hybrids as lacking in sufficient homology between the regulatory RNA's and paternal genome which can then lead to the spectrum of abnormal hybrid dysgenesis phenotypes. In this proposal we hope to test this possibility by restoring a greater degree of homology between the paternal nuclear compartment and the oocyte cytoplasmic compartment, including stored regulatory small molecules by creating the first "true" interspecies hybrids. True hybrids will possess equal, or nearly so, contributions of both nucleus and cytoplasm from both parental species. We have chosen to use Mus musculus: caroli or spretus hybrids and assess them for viability, male infertility and somatic growth/obesity. If successful this approach can be used to characterize other interspecies hybrids. These experiments lay the groundwork for an increased understanding of how early events after fertilization program the zygote genome and as such will inform epigenetic gene regulation, transposon regulation, the reprogramming of a somatic cell nucleus in animal cloning, and evolution/speciation. PUBLIC HEALTH RELEVANCE: The discovery of RNA silencing systems has dramatically altered our understanding of gene regulation. Nowhere is this more important than in the germ lines and early embryo. Interspecies hybrids provide a tool to understand how genes are normally epigenetically modified and programmed throughout development. This goal of this project is to determine if the abnormalities seen in interspecies hybrids (hybrid dysgenesis) can be lessened by increasing the homology between the oocyte cytoplasm and the zygote pronuclei.