Biodiversity of Chironomidae (Diptera) and genome response to trace metals in the environment

The effects of pollution on the biodiversity and genome response of Chironomidae larvae (Diptera, Insect) were evaluated in the trace metal contaminated water environments. No change on the Chironomid species diversity was found. The higher concentrations of trace metals (Cd, Pb, Cr, and Zn) affect the genome of 5 cytogenetically studied Chironomid species: Chironomus bernensis, C. plumosus, C. sp.1. Kiefferulus tendipediformis (cytotype 2), Glyptotendipes cauliginellus (syn. Glyptotendipes gripekoveni). Genome instability of Chironomid larvae was manifested by two ways: 1. Fixed chromosome rearrangements; homozygous inversions and tandem fusions created new gene linkage groups and show an intensive microevolutionary process of species. 2. Somatic structural (inversions, deficiencies, deletions, breaks); and functional alterations (decreasing the activity of the key structures: Balbiani rings (BRs) and Nucleolar Organizer (NOR)) in salivary gland chromosomes of cytogenetically studied Chironomidae species. Detecting somatic rearrangements in salivary gland chromosomes of these widely distributed aquatic insects is potentially one of the best validated bioassay and can be used as a cost effective early warning signals of environmental damage in freshwater basins.