Chromosomes study techniques

The types of chromosomal alterations that appear as a consequence of the break depend upon the site of the break in the chromosome. Thus, inasmuch as the distribution of the breaks is believed to be random, irradiated cells can be expected to exhibit a broad panoply of chromosomal alterations. Therefore, ionizing radiation has long been a most useful tool for investigating chromosomal damage. At first, the studies were done on cells with large chromosomes such as those of Drosophila or Vida faba, but the development of new techniques in chromosomal studies has permitted direct observation of chromosomal damage in mammalian cells including human cells. 

Genetic Control. Manipulation of the mechanisms of inheritance of the insect pest populations has occurred most successhiUy through the mass release of steri1i2ed males, but a variety of other techniques have been studied, including the environmental use of chemostetilants and the mass introduction of deleterious mutations, eg, conditional lethals and chromosomal translocations (58 ndash 60) (see Genetic engineering). 

The expression of many of these molecules has been studied during various stages of differentiation of normal neutrophils and also of corresponding leukemic cells employing molecular biology techniques (eg, measurements of their specific mRNAs). For the majority, cDNAs have been isolated and sequenced, amino acid sequences deduced, genes have been localized to specific chromosomal locations, and exons and intron sequences have been defined. Some important proteinases of neutrophils are listed in Table 52-12. 

Fluorescence microscopy techniques were also applied to study chromatin and chromosomes,(179) but those studies lie outside the scope of this chapter. 

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