Immunological detection of left‐handed Z DNA in isolated polytene chromosomes. Effects of ionic strength, pH, temperature and topological stress.
Immunological detection of left‐handed Z DNA in isolated polytene chromosomes. Effects of ionic strength, pH, temperature and topological stress.
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分离多线染色体中左手 Z DNA 的免疫学检测。离子强度、pH、温度和拓扑应力的影响。
DOI：
10.1002/j.1460-2075.1984.tb01875.x
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
T. Jovin
中科院分区：
文献类型：
--
作者：
M. Robert‐Nicoud;D. Arndt;D. Zarling;T. Jovin
我们在从摇蚊幼虫唾液腺中分离的未固定多线染色体中寻找左手Z DNA的存在。探索生理和固定条件，以评估已知影响B-Z平衡的各种因素的影响。在中性pH和生理离子强度下，仅通过使用高浓度的抗Z DNA免疫球蛋白（IgG），才能引发局限于染色体条带周边的弱免疫荧光染色。在这些条件下，用抗核心组蛋白的抗体监测的内部高度浓缩结构的可及性非常有限。增加离子强度暴露了核心组蛋白决定簇，但导致条带的解凝聚。Z DNA的染色仍然很弱，主要局限于抵抗解凝聚或经历崩溃的区域。在短时间暴露于低pH值时，抗Z DNA免疫荧光强度发生显著变化。将pH值调节至2.5至2.0之间，导致抗体结合率突然大幅增加，最初仅限于几条特定条带，然后以与经典酸固定南瓜制剂非常相似的模式推广至整个染色体的条带。酸介导的效应受离子强度、温度和组蛋白去除的影响;它们可以通过在中性pH下暴露于高温来模拟。用对左手d（G-C）n序列特异性的单克隆IgG评估的“转变pH”略低于也识别d（A-C）n X d（G-T）n的多克隆抗体。（400字处截断摘要）
We have searched for the presence of left‐handed Z DNA in unfixed polytene chromosomes isolated from the salivary glands of Chironomus thummi larvae. Physiological as well as fixation conditions were explored to assess the effects of a variety of factors known to influence the B‐Z equilibrium. At neutral pH and physiological ionic strength, a weak immunofluorescence staining confined to the periphery of chromosomal bands is elicited but only by using high concentrations of anti‐Z DNA immunoglobulin (IgG). The accessibility of internal highly condensed structures, as monitored with antibodies against core histones, is very limited under these conditions. Increasing the ionic strength exposes core histone determinants but results in a decondensation of the bands. The staining for Z DNA is still weak and primarily restricted to regions resisting decondensation or undergoing collapse. Dramatic changes in anti‐Z DNA immunofluorescence intensities occur upon short exposure to low pH. Adjustment of the pH between 2.5 and 2.0 leads to an abrupt large increase in antibody binding, at first confined to a few specific bands and then generalized to bands throughout the chromosomes in a pattern very similar to that elicited in classical acid‐fixed squash preparations. The acid‐mediated effects are influenced by ionic strength, temperature and prior removal of histones; they can be mimicked by exposure to high temperature at neutral pH. The ‘transition pH’ assessed with a monoclonal IgG specific for left‐handed d(G‐C)n sequences is slightly lower than in the case of polyclonal antibodies which also recognize d(A‐C)n X d(G‐T)n.(ABSTRACT TRUNCATED AT 400 WORDS)