Chromatid-type deletions

Chromatid-type aberrations are believed to be induced by chemicals. In occupational monitoring it is very important to pay attention to this type of aberration. Some percentile values of chromatid deletions (without gaps) were collected and found by different authors (Table 15.7). A 2-fold difference exists between our data and that of others (0.44 vj... 

The nucleus of all eucariotic cells contains the carrier of the genetic information in the chromosomes. It is possible to visualize the chromosomes and analyze their number and pattern during a special period of cell division (the metaphase). Alterations from their normal shapes are observed as structural chromosome aberrations. These are chromosome type aberrations (terminal and interstitial deletions, dicentrics and rings), chromatid aberrations (gaps, breaks and exchanges) and sister chromatid exchanges. Spontanous frequencies of such chromosome... 

The classification and nomenclature of the International System for Human Cytogenetic Nomenclature (ISCN, 1985) as applied to acquired chromosome aberrations is recommended. Score sheets giving the slide code, microscope scorer s name, date, cell number, number of chromosomes and aberration types should be used. These should include chromatid and chromosome gaps, deletions, exchanges and others. A space for the vernier reading for comments and a diagram of the aberration should be available. 

Related Tests. Many cells exposed to test chemicals can be scored for chromosome aberrations by staining procedures followed by visual examination with the aid of the microscope. These include Chinese hamster ovary cells in culture treated in a protocol very similar to that used in the test for SCEs, bone marrow cells from animals treated in vivo, or lymphocytes from animals treated in vivo. The types of aberrations evaluated include chromatid gaps, breaks, and deletions chromosome gaps, breaks, and deletions chromosome fragments translocations and ploidy. 

Group Total No. of cells Abeitant cells No. % chromatid deletions No. % Type of aberration chromosome fragments No. % dicentrics No. % ... 

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