Somatic DNA Alterations of the 81 Locus of Oxytricha trifallax: Mechanisms and Evolution of its Alternative Processing

9600663赫里克对纤毛虫进行的一项系统发育调查将监测棘毛虫81个基因座加工的起源和分子进化。人们对这81个基因座特别感兴趣，因为已有研究表明，在体细胞大核发育过程中，它被加工成三条重叠的大核染色体。系统发育调查将使用代表更远亲缘纤毛虫DNA替代处理的大核间隔的简并引物聚合酶链式反应。将对扩增的DNA进行测序和分析，以获得分子和关系方面的见解，并确定进一步简并的聚合酶链式反应引物的设计，以检测更远距离的相关序列。纤毛虫通过以程序化的方式消除特定的DNA序列来处理它们的生殖核来产生体细胞核。有一个特殊的位点，即Oxytricha Falfax的81位点，已经被证明是不寻常的，因为它被交替处理以产生三个重叠的片段，总共有三个开放阅读框。本研究将利用这一区域比较相关的下毛纤毛原生动物DNA中的相关序列，以期了解程序性基因重排的进化。这种程序性DNA重排在哺乳动物肿瘤发生过程中的免疫细胞基因重排和随机重排中观察到，深入了解这些简单原生动物的进化过程可以为理解更复杂的生物体的过程提供基础。***

9600663 Herrick A phylogenetic survey across a spectrum of ciliates will monitor the genesis and molecular evolution of the processing of the 81 locus of Oxytricha fallax. The 81 locus is of particular interest because it has been shown that during the development of the somatic macronucleus it is processed to form three overlapping macronuclear chromosomes. The phylogenetic survey will be done with degenerate-primer PCR of macronuclear intervals representative of alternative processing in the DNAs of ever more distantly related ciliates. The amplified DNAs will be sequenced and analyzed for molecular and relational insights as well as determining the design of further degenerate PCR primers to permit detection of more distantly related sequences. %%% Ciliates process their germline nucleus to produce a somatic nucleus by eliminating specific DNA sequences in a programmed fashion. One particular locus, the 81 locus of Oxytricha falfax, has been shown to be unusual in that it is alternatively processed to produce three overlapping fragments with a total of three open reading frames. This study will use this region for a comparison of the involved sequence in DNA from related hypotrichous ciliated protozoa in the hope of understanding the evolution of programmed gene rearrangements. Such programmed DNA rearrangements are observed in immune-cell gene rearrangements and stochastic rearrangements during tumorigenesis in mammals and insight into the evolution of the process in these simple protozoa can provide a basis of understanding of the process in more complex organisms. ***