Grigliatti T
Department of Zoology, University of British Columbia, Vancouver, Canada.
Methods Cell Biol. 1991;35:587-627.
The past decade has brought us much information about gene regulation in eukaryotes and the importance of chromatin in gene expression. Clearly, we need to advance our understanding of chromatin assembly and modification. Hopefully, many Su(var) and E(var) loci will be cloned and their analysis will demonstrate that they are involved in this process. It will be interesting to see what classes of products they encode. Clearly, antibodies must be made against these proteins to determine: (1) the chromosomal distribution of those that encode chromatin structural proteins, (2) the tissue and temporal distribution of these proteins during development, and (3) the time of action during specific portions of the cell cycle for those genes encoding factors that regulate chromatin assembly or modifying proteins. In addition, it would be intriguing to identify and isolate those sequences or segments of DNA that serve as nucleation sites for the assembly of euchromatin and heterochromatin. The necessary materials for identifying these sequences are in place with the large number of variegating strains and revertants of those rearrangements and Su(var) and E(var) mutations that exist. From our current understanding of PEV, it appears that PEV provides a useful model for the study of determinative events that occur during development. This includes both the establishment of different lineages and the somatic memory or imprinting of the initial determinative decision. Clearly, PEV is more than a simple assay system for the identification of NHCPs, and ultimately the understanding of the mechanisms underlying PEV should lend insights into how such determinative events occur and are propagated.
过去十年为我们带来了许多关于真核生物基因调控以及染色质在基因表达中的重要性的信息。显然,我们需要加深对染色质组装和修饰的理解。有望克隆出许多抑制变异性(Su(var))和增强变异性(E(var))基因座,对它们的分析将表明它们参与了这一过程。看看它们编码的产物属于哪些类别将会很有趣。显然,必须制备针对这些蛋白质的抗体,以确定:(1)那些编码染色质结构蛋白的蛋白质在染色体上的分布,(2)这些蛋白质在发育过程中的组织和时间分布,以及(3)对于那些编码调节染色质组装或修饰蛋白的因子的基因,其在细胞周期特定阶段的作用时间。此外,识别和分离那些作为常染色质和异染色质组装成核位点的DNA序列或片段将会很有趣。利用现有的大量存在重排、抑制变异性(Su(var))和增强变异性(E(var))突变所导致的斑驳菌株和回复体,识别这些序列所需的材料已经具备。从我们目前对位置效应斑驳(PEV)的理解来看,PEV似乎为研究发育过程中发生的决定性事件提供了一个有用的模型。这包括不同细胞谱系的建立以及初始决定性决定的体细胞记忆或印记。显然,PEV不仅仅是一个用于鉴定非组蛋白染色体蛋白(NHCPs)的简单检测系统,最终,对PEV潜在机制的理解应该有助于深入了解此类决定性事件是如何发生和传播的。