System for Laser/Mechanical Dissection of Chromosomes

越来越多的疾病与特定的染色体异常有关，如易位、倒位和缺失。选择单个染色体g带，可以制备用于染色体分析和鉴定这些异常的临床诊断探针。目前，所需的染色体带是通过将其从载玻片上刮下来，用附着在液压机械手上的微移液管，同时使用配有100倍物镜的倒置显微镜监测这一过程来去除的。针大致垂直于感兴趣的染色体，既将所需的材料与染色体的其余部分区分开来，又将材料移出以供后续处理。在我们开发的新系统中，使用紫外（390nm）激光非常清晰地划分要获取的材料并烧蚀周围的材料。然后，在计算机控制下，由专门开发的机构移动的微移液管将所需的材料移出。希望通过依靠激光修剪掉不需要的物质，将有更少的外来物质比使用微移管的剪切作用将样品从剩余物质中分离出来。此外，通过物镜聚焦位置和视频图像感知针尖位置，以及利用计算机确定机构的运动，将大大降低对操作人员的手工灵巧性要求，从而使该技术得到更广泛的应用。新系统仍在评估中。似乎静电效应有时会干扰刮刮材料在其收集试管中的沉积。人们正在探索消除这种影响的各种方法。

An increasing number of diseases are being associated with specific chromosomal abnormalities, such as translocations, inversions, and deletions. Selection of individual chromosome G-bands allows preparation of clinical diagnostic probes for chromosomal analysis and identification of these abnormalities. Presently, the desired chromosome band is removed by scraping it off a slide with a micropipette attached to a hydraulic manipulator while monitoring the process using an inverted microscope equipped with a 100X objective lens. The needle, oriented approximately perpendicularly to the chromosome of interest both demarcates the desired material from the rest of the chromosome, and removes the material for subsequent processing. In a new system we have developed, a UV (390nm) laser is used to very sharply demarcate the material to be acquired and ablate the immediate surrounding material. The desired material is then removed by a micropipette moved by a specially developed mechanism under computer control. It is hoped that by relying on the laser to trim away the undesired material, there will be less extraneous material than when the shearing action of the micropipette is used to separate out the sample from the remaining material. In addition, by sensing the needle tip position with the objective lens focus position and a video image, as well as employing a computer to determine the motions of a mechanism, the manual dexterity requirements on the operator will be greatly reduced, thus allowing the technique to be more widely used. The new system is still being evaluated. It appears that static electricity effects sometimes interefere with the deposition of the scraped material into its collection cuvette. Various means of eliminating the effect are being explored.