A STUDY OF TRANSVECTION AT THE DROSOPHILA YELLOW GENE

拟议的研究通过关注transvection来探索果蝇染色质结构水平上的基因调控，transvection是一种不寻常的基因调控形式，反映了基因与其同源物的接近程度。 它解决了在黄色基因的transvection。 在这里，transvection是基因内互补的基础。 特别是，研究表明，当某些等位基因配对时，一个等位基因的增强子可以反式作用于另一个等位基因的启动子。 这些数据还表明，释放增强子以反式发挥作用的先决条件可能是使其自身的启动子失能。 初步研究已在这一模型基础上进行了相当大的扩展。 此外，他们提出了第二种模式的transvection，其中配对的不同等位基因导致基因拓扑结构，允许增强子绕过染色质绝缘子。 拟议的研究测试并扩展了这些令人惊讶的新的对黄色横向的解释。特异性目的1测试了其中反式增强子作用由启动子的转录能力控制的模型。具体目标2测试的建议，配对可以决定基因拓扑结构，允许增强子绕过绝缘子。 在具体目标3中，研究超越了黄色，并询问基因和基因组是否通常允许transvection。 最后，具体目标4寻找介导和控制transvection的trans-acting因素。 我们的研究使用两种技术来满足同源配对的transvection要求。 这些是靶向基因转换（特定目标1，2和3）和一种允许将基因放置到不同染色体上的等位基因位置的技术（特定目标3）。 具体目标4使用标准的遗传和分子生物学方法。有强有力的证据表明，同源配对是一种强大的力量，可以在许多生物体中造成严重的后果。 它可能成为某些医学疾病的基础，并限制某些农业技术。 因此，这里的研究很可能通过对医学和农业的贡献来造福人类福利。

The proposed research explores gene regulation at the level of chromatin structure in Drosophila by focusing on transvection, an unusual form of gene modulation that reflects the proximity of a gene to its homologue. It addresses transvection at the yellow gene. Here, transvection is the basis for intragenic complementation. In particular, studies indicate that when certain alleles are paired, the enhancers of one can act in trans on the promoter of the other. The data also suggest that a prerequisite for the release of an enhancer to act in trans may be the disabling of its own promoter. The preliminary studies have expanded considerably upon this model. In addition, they suggest a second mode of transvection in which the pairing of dissimilar alleles leads to gene topologies that allow an enhancer to bypass a chromatin insulator. The proposed research tests and extends these surprising and new interpretations of transvection at yellow. Specific Aim 1 tests the model in which enhancer action in trans is controlled by the transcriptional competence of the promoter. Specific Aim 2 tests the proposal that pairing can dictate gene topologies to allow an enhancer to bypass an insulator. In Specific Aim 3, the studies extend beyond yellow and ask whether genes and the genome are generally permissiveness for transvection. Finally, Specific Aim 4 searches for the trans- acting factors that mediate and control transvection. Our studies use two technologies to meet the requirement of transvection for homologue pairing. These are targeted gene conversion (Specific Aims 1, 2, and 3) and a technique that allows the placement of genes into allelic positions on different chromosomes (Specific Aim 3). Specific Aim 4 uses standard genetic and molecular biological approaches. There is strong evidence that homologue pairing is a potent force that can cause severe consequences in many organisms. It may underlie some medical diseases and limit certain agricultural technologies. Therefore, the studies here are likely to benefit human welfare through contributions to both medicine and agriculture.