Molecular and Genetic Studies on Maize Transposable Elements-- Paramutation and Directed Transposition

玉米Ac-Ds系统转座因子之间的新相互作用将被研究。初步研究表明，Ds元素与同源染色体上的Ac-w衍生物之间存在相互作用或某种形式的信息传递。一条染色体上高度甲基化的wx-m9Ds-cy元件的存在导致同源物上远端Ac-w元件的参数化样失活和甲基化。wx-m6、wx-m9中的Ds元素和i9染色体标准位置上的I态Ds元素不会失活，但在每个杂合子中，会导致Ac-w沿着其染色体移动，并重新插入到同系物上Ds元素所占据的位置。wx-m1等位基因中的小d1元件不反式作用，必须在同一染色体上才能影响Ac-w的迁移。分子证据表明Ac-w被重新插入到wx-m1基因中。这些相互作用仅限于同源染色体上的元素。这些研究将得到扩展，并将通过遗传和分子分析来研究它们之间的相互作用。虽然在分子水平上对转座因子有很多了解，但本研究首次表明定向转座和位点特异性插入可以并且确实发生。这个项目的继续将允许收集更多的信息，这可能是一个潜在的突破，试图了解什么，如果有的话，在正常的，非胁迫的玉米基因组中的转座元件执行的功能。

Novel interactions between the transposable elements of the Ac-Ds system in maize will be investigated. Preliminary studies indicate interaction or some form of information transfer between Ds elements and Ac-w derivatives on homologous chromosomes. The presence of the highly methylated wx-m9Ds-cy element on one chromosome leads to the paramutation-like inactivation and methylation of an Ac-w element at a distant position on the homologue. The Ds elements in wx-m6, wx-m9 and the State I Ds in standard position on chromosome II 9 do not inactivate but, in every heterozygote, cause Ac-w to move along its chromosome and be reinserted at the site occupied by the Ds element on the homologue. The small Ds I element in the wx-m1 allele does not act in trans and must be on the same chromosome to effect the migration of Ac-w. Molecular evidence indicates that Ac-w is reinserted in the wx-m1 gene. These interactions are limited to elements on homologous chromosomes. These studies will be extended and the interactions by genetic and molecular analyses wil be investigated. While much is known about transposable elements on the molecular level, this study is the first to suggest that directed transposition and site-specific insertion can and does occur. The continuation of this project will allow further information to be gathered on what could be a potential breakthrough on attempts to understand what, if any, function is performed by transposable elements in the normal, non-stressed genome of corn.