Elucidating mechanisms of gene restoration

孟德尔的遗传定律在上个世纪的大部分时间里指导着我们对古典遗传学和分子遗传学的探索。根据这些规律，遗传性状独立分离，并稳定地代代相传。尽管存在明显的稳定继承法则例外，但所有例外都有相对明确的定义。我们最近证明，与HOTHEAD基因座隐性突变等位基因纯合的拟南芥植物可以遗传亲本染色体基因组中缺失的DNA序列信息。我们发表的数据表明，整个核基因组的序列都容易发生变化，编码区和非编码区都受到影响。另外的研究结果表明，删除的序列可以准确地恢复，并表明该过程是模板导向的。毫不奇怪，这些发现极具争议。标准的遗传和分子方法将被用来阐明这一过程的显著特征。将努力确定假定模板的分子性质和细胞位置。报告基因结构将用于确定发育中的细胞何时经历序列变化以及哪些特定组织或细胞受到影响。将进行突变分析，以确定哪些其他途径可能交叉和/或调节逆转。实验还提出将确定植物是否仍然可以获得祖先序列信息10代移除。这样，这种现象的持续性就会得到阐明。如果这一过程被证明是普遍的，并且植根于古老的“RNA世界”，那么其他生物体完全有可能表现出这种类型的非孟德尔遗传。如果事实证明是这样，正如Rassoulzadegan等人最近在《自然》杂志上发表的一篇文章所表明的那样，其医学和生物技术意义将是深远的。

Mendel's laws of inheritance have guided our exploration of classical as well as molecular genetics through much of the last century.  According to these laws genetic traits segregate independently and are inherited stably from one generation to the next.  Although notable exceptions to the law of stable inheritance exist, all have been relatively well defined.  We have recently demonstrated that Arabidopsis plants homozygous for recessive mutant alleles of the HOTHEAD locus can inherit DNA sequence information that is absent from the chromosomal genome of their parents.  Our published data suggest that sequences throughout the nuclear genome are susceptible to change and that both coding and non-coding regions are affected. Additional research results demonstrate that deleted sequences can be accurately restored and suggest that the process is template-directed. Not surprisingly, these findings are extremely controversial.Standard genetic and molecular approaches will be used to elucidate the salient features of this process.  Efforts to determine the molecular nature and cellular location of the putative template will be made.  Reporter gene constructs will be used to establish when in development cells experience sequences changes and what specific tissues or cells are effected. Mutant analyses will be undertaken to determine what other pathways might intersect and/or regulate reversion. Experiments are also proposed that will determine whether plants 10 generations removed can still acquire ancestral sequence information.  In this way, the persistence of the phenomenon will be elucidated.Should this process prove universal and have roots in the ancient 'RNA world' it is entirely possible that other organisms may manifest this type of non-mendelian inheritance. If this proves to be the case, as is suggested by a recent Nature publication by Rassoulzadegan et al, the medical and biotechnological implications are profound.