An increasing number of diseases are being associated with specific chromosomal abnormalities, such as translocations, invertions, 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 micropippette 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 under development, 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 micropippette 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 micropippette is used to separate out the sample from the remaing 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.
