Abstract
Chromatin diminution is the loss of selected regions of pre-somatic cell chromosomes during early development, resulting in the removal of a large amount of the genomic DNA from the pre-somatic cells. In copepods, diminution is characterized by the formation of heterochromatically staining regions, or H-segments, which contain the chromatin to be lost. The removal of H-segments during diminution also must represent a major restructuring of the chromosomes which contained them. In order to examine the effects of diminution on the morphology and structure of the chromosomes, the C-banding technique was used. This procedure revealed that most C-bands present in the pre-diminution complement were absent in the post-diminution set. Additionally, in order to explore further the possible composition of the DNA contained in H-segments, a comparison, based on the relationship of C-bands to highly-repetitive DNA in chromosomes, was made between pre-diminution C-bands and H-segments. This comparison showed that not all H-segments are at chromosomal locations which produce a C-band, indicating that H-segments are perhaps not entirely composed of genetically inert DNA, as is currently supposed.
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Standiford, D.M. The effects of chromatin diminution on the pattern of C-banding in the chromosomes of Acanthocyclops vernalis Fischer (Copepoda: Crustacea). Genetica 79, 207–214 (1989). https://doi.org/10.1007/BF00121514
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DOI: https://doi.org/10.1007/BF00121514