CYTOGENETIC CHARACTERISTICS OF A POPULATION OF CHIRONOMUS-RIPARIUS MEIGEN 1804 (DIPTERA, CHIRONOMIDAE) FROM A POLLUTED PO RIVER STATION

Citation
P. Michailova et al., CYTOGENETIC CHARACTERISTICS OF A POPULATION OF CHIRONOMUS-RIPARIUS MEIGEN 1804 (DIPTERA, CHIRONOMIDAE) FROM A POLLUTED PO RIVER STATION, Genetica, 98(2), 1996, pp. 161-178
Citations number
33
Categorie Soggetti
Genetics & Heredity
Journal title
ISSN journal
00166707
Volume
98
Issue
2
Year of publication
1996
Pages
161 - 178
Database
ISI
SICI code
0016-6707(1996)98:2<161:CCOAPO>2.0.ZU;2-#
Abstract
A population of Chironomus riparius from a Po river station near Monca lieri (a trace-metal polluted station) was studied. In this population was established a great variability of band structure of polytene chr omosomes as well as paracentric heterozygous inversions, deletions, de ficiencies, partial breaks, diploid chromosome fragments, and changes in functional activity and appearance of heterochromatin. In arms A th rough F, some bands had an increased size compared to the standard chr omosomic map. Some bands appeared in a heterozygous or normal homozygo us state or were amplified. In all arms, many condensed stable bands a ppeared in the decondensed state when compared to the standard map. As ynaptic zones in arms E and G as well as heterozygous Balbiani rings a nd NORs were established. Very often the 4th chromosome was almost com pletely heteropycnotic and looked like a 'pompon' chromosome. For the first time in this species, a high frequency of ectopic pairings of di fferent arms was observed. Telomeric regions involved in ectopic pairi ngs had a granular appearance, as did some centromeres. The hypothesis is advanced that such a high frequency of structural rearrangements c ould be correlated with genomic distribution of specific mobile elemen ts.