Localization of Constitutive Heterochromatin in the Chromosomes of Drosophila virilis


Biochemical investigations have shown that constitutive heterochromatin is composed primarily of highly repetitive DNA termed satellite DNA (Yunis and Yasmineh 1970, 1971a, 1971b, Arrighi et al. 1970). Recent advances in cytological techniques have allowed the visualization of these heterochromatic regions of metaphase chromosomes (Caspersson et al. 1969, Arrighi and Hsu 1971). Such techniques have facilitated the study of the distribution of heterochromatin in metaphase chromosomes when both euchromatin and heterochromatin are fully condensed and differentiation of chromosomes into euchromatic and heterochromatic parts disappears. Heitz (1934) reported that large amounts of heterochromatin were present in the chromosomes of Drosophila virilis. Through studies of the mitotic cycle, Makino (1940) described the distribution of heterochromatin in the chromosomes of D. virilis. More recently Adkisson et al. (1971) used quinacrine mustard to investigate the heterochromatin of D. virilis chromosomes and found large heterochromatic regions in every chromosome. Gall et al. (1971) and Schweber (1974) have reported that satellite DNA comprises over 40 percent of the total DNA of the diploid cells of D. virilis. This represents one of the largest amounts of satellite DNA reported for any organism. This study involved the use of the C-banding technique of Hsu (1971) to determine the distribution of constitutive heterochromatin in the neuroblast chromosomes of D. virilis. © 1977, Japan Mendel Society, International Society of Cytology. All rights reserved.

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