Investigations of Mouse Interspecies Hybrids

描述（由申请人提供）：种间杂交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/早期着床前致死到男性不育的生存能力。近年来，人们发现小沉默RNA在卵母细胞和雄性种系中对胚胎发育和配子体发生起着重要作用。这些RNA的作用之一被认为是控制转座因子（TE），它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方面也很重要。这种理解的一个后果是将种间杂交视为在调节RNA和父本基因组之间缺乏足够的同源性，从而导致异常杂交发育不良表型的频谱。在这个提议中，我们希望通过恢复父系核室和卵母细胞细胞质室之间更大程度的同源性来测试这种可能性，包括通过创造第一个“真正的”种间杂交来存储调节小分子。真正的杂交种将具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贡献。我们选择使用小家鼠：caroli或spretus杂交，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，这种方法可以用来描述其他种间杂交的特征。这些实验为进一步了解受精后的早期事件如何规划受精卵基因组奠定了基础，因此将为表观遗传基因调控、转座子调控、动物克隆中体细胞细胞核的重编程和进化/物种形成提供信息。

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.