Cytogenetic characteristics of a population of Chironomus riparius Meigen 1804 (Diptera, Chironomidae) from a polluted Po river station

Abstract

A population of Chironomus riparius from a Po river station near Moncalieri (a trace-metal polluted station) was studied. In this population was established a great variability of band structure of polytene chromosomes as well as paracentric heterozygous inversions, deletions, deficiencies, partial breaks, diploid chromosome fragments, and changes in functional activity and appearance of heterochromatin. In arms A through E some bands had an increased size compared to the standard chromosomic map. Some bands appeared in a heterozygous or normal homozygous state or were amplified. In all arms, many condensed stable bands appeared in the decondensed state when compared to the standard map. Asynaptic zones in arms E and G as well as heterozygous Balbiani rings and NORs were established_ Very often the 4th chromosome was almost completely heteropycnotic and looked like a 'pompon' chromosome. For the first time in this species, a high frequency of ectopic pairings of different arms was observed. Telomeric regions involved in ectopic pairings had a granular appearance, as did some centromeres. The hypothesis is advanced that such a high frequency of structural rearrangements could be correlated with genomic distribution of specific mobile elements.

Genomic alterations recorded in two species of Chironomidae (Diptera) in the Upper Jurassic limestone area of the Ojców National Park in Poland attributable to natural and anthropogenic factors

“…The results obtained in this study confirm the idea of Michailova et al (1996), Logadic & Caquet (1998) and Steinberg et al (2008) that the genome is very sensitive to changes in the environment and demonstrate that changes in the genome can be used to detect pollutants in aquatic ecosystems. Moreover, the results also show that the response of species at the cytogenetic level, i.e.…”

Chironomids (Diptera) and their salivary gland chromosomes as indicators of trace-metal genotoxicity

“…Somatic aberrations occur during the embryonic phase, prior to the onset of the polytenization process (Hägele 1970;Sorsa 1988). They can be used to assess the genotoxic effect of stress agents in the environment and can be considered to be the best markers of trace-metal genotoxicity (Michailova et al 1996). Among somatic deletions, especially interesting are deletions on the short acrocentric chromosome G of C. riparius.…”

“…Aberrations are considered inherited when they affect all cells in both salivary glands of the same individual. Generally they occur at low (∼1%) frequencies in C. riparius and C. piger (Michailova et al 1996;Sella et al 2004;Michailova et al 2009a) or at >1% frequencies in C. plumosus (Butler et al 1999;Gunderina et al 1999). Inherited aberrations can result either from an aberration that occurred in the zygote or from the heritage of the parents.…”

“…Namely, they performed two types of genotoxicity tests-the Somatic Mutation and Recombination Assay (SMART), and Sex Linked Lethal Recessive Test (SLRLT)-and cautioned that these can be applied only to one indicator group, Drosophila melanogaster. In addition, Michailova et al (1996Michailova et al ( , 1998 showed that the appearance of somatic aberrations on the polytene chromosomes of Chironomids was a very promising method for assessing the genotoxic effects of environmental contaminants.…”

Polytene Chromosome aberrations based Genotoxicity evaluation of Dichlorvos insecticide using Drosophila malenogaster

“…Scientific literature review suggested that mutagens which affect the structural integrity of genetic material cause ectopic pairings. Numerous investigation indicated that in polyene chromosomes of different organisms including Chironomus acidophilus, Chironomus riparius and Glyptotendipes salinus exposed to different concentrations of trace metals like Al, Cr, Pb and Cu, incidences of ectopic pairings were there, as expression of abnormal interaction of different mutagens [38][39][40][41] . The incidence of ectopic pairings was dependent on the organization of the genome in the polytene chromosomes of an organism and interspersed repetitive DNA 42 .…”