Analysis of the ectopic interactions of Drosophila melanogaster polytene chromosomes in the H-E hybrid dysgenesis system
1992
Ivashchenko, N.I. | Vagapova, R.B. | Bogdanov, Yu.F.
Analysis of Drosophila melanogaster third instar larval salivary gland polytene chromosomes showed that most of the rearrangements resulting from mobilization of the hobo element are inversions. The frequency of these events was increased by gamma-irradiation. The fact that both gamma-irradiation and transposition of mobile elements can have significant effects on the homology of associating regions led us to analyze ectopic chromosomal contacts. This approach revealed features common to all types of crosses, i.e., intrachromosomal contacts were more frequent than interchromosomal contacts, both types of contact were preferentially located in the telomeric regions of the chromosomes, and the frequency of contacts was lower in the X chromosome of males than in the X chromosome of females. On the other hand, the analysis allowed the specificity of ectopic conjugation in different types of cross to be determined. While the mean number of contacts in the D. melanogaster genome remained constant, there were differences in their distributions among the chromosomes. The chromosomes of pure lines differed from their homologs in dysgenic hybrids both in terms of the distribution of peaks and in terms of the localization of several unique events in ectopic conjugation. These experiments, along with data in the literature, were used to analyze the function of ectopic contacts as structures joining chromosomal regions with similar functional activities, rather than with similar nucleoprotein properties.
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