Polytene chromosomes of Chironomidae (Diptera) as a bioassay of trace-metal-induced genome instability

Chironomids are a ubiquitous group of aquatic insects that are very sensitive to environmental stress. Due to the presence of polytene ('giant') salivary gland chromosomes, it is possible to define the genome response of several Chironomid species to various stress agents. The aim of this study was to assess the genotoxic changes in populations of widely distributed chironomid species from aquatic basins in Bulgaria, Italy, Russia, U.K. and Poland, which were exposed to high concentrations of trace metals. We analyzed the structural and functional alterations of polytene chromosomes of the salivary glands of larvae belonging to three different cytocomplexes of the genus Chironomus ("thummi", "lacunarius", "pseudothummi"), and genera Glyptotendipes and Kiefferulus. Somatic structural chromosome rearrangements (para- and pericentric heterozygous inversions, deletions, deficiencies and amplifications) were used to estimate a Somatic index (S) for each population. The highest S indexes were detected in Chironomus riparius populations from locations with high concentrations of trace metals in the sediment. Each species showed specific genome responses to stress agents which we discussed in the light of the specific DNA structures and cytogenetic characteristics of the species. In larvae from polluted sediments two key structures of the salivary gland chromosomes (Balbiani Rings and Nucleolar Organizer) sharply reduced their activity to levels below those observed under non-polluted conditions. It is concluded that polytene chromosomes can be used as tools for evaluating the genotoxicity of the aquatic environment. Structural and functional chromosome alterations provide cost-effective early-warning signals of genotoxic concentrations of environmental pollutants. doi: 10.5324/fn.v31i0.1355. Published online: 17 October 2012

Firuz Akhrorov (1937-2012) and his contributions to the study of Chironomidae in Tajikistan

The paper is dedicated to the memory of Firuz Akhrorov (1937-2012), noted Tajik hydrobiologist and chironomid researcher. The contributions of F. Akhrorov to chironomid research are reviewed briefly. A list of Akhrorov's published works on Chironomidae (35 titles) is provided, as is a list of taxa he described in Chironomidae (18 species names)

Genotoxic effects of chromium onpolytene chromosomes of Chironomus riparius Meigen 1804 (Diptera, Chironomidae)

Abstract Genotoxic effect as tested of chronic exposure to three different concentrations of Chromium (III) on polytene chromosomes of larvae of Chironomus riparius (syn. Chironomus thummi) from the embryonic stage to the IV larval instar for two successive generations. In chromosomes AB, CD, EF and G significant differences of chromosome aberrations were found between exposed and control larvae as well as changes in functional activity (induction of novel puffs not corresponding to those induced during normal larval development in arms A, B, C and E, telomeric and centromeric decondensations especially at telomeres of chromosome G and arm C.). No significant differences were found between the effects of the three treatments nor between the two generations. In chromosome G the Balbiani Ring system (where some permanently active regions are involved in transcription of salivary proteins) appeared as a model for studying the response of the genome to Cr (III) treatment. In approximately one-third of the cel..

Karyotypical characteristics of two allopatric African populations of anhydrobiotic Polypedilum Kieffer, 1912 (Diptera, Chironomidae) originating from Nigeria and Malawi

The African chironomid Polypedilum vanderplanki Hinton, 1951 is the only chironomid able to withstand almost complete desiccation in an ametabolic state known as anhydrobiosis. The karyotypes of two allopatric populations of this anhydrobiotic chironomid, one from Nigeria and another from Malawi, were described according to the polytene giant chromosomes. The karyotype from the Nigerian population was presented as the reference chromosome map for P. vanderplanki. Both populations, Nigerian and Malawian, showed the same number of chromosomes (2n=8), but important differences were found in the band sequences of polytene chromosomes, and in the number and the arrangement of active regions between the two populations. Such important differences raise the possibility that the Malawian population could constitute a distinct new species of anhydrobiotic chironomid

Polytene chromosomes of chironomids and midges and use thereof for studying systematics and evolution of these groups of insects (diptera, chironomidae and simullidae)

The investigation is concerned with chironomids and bloodsucking midges. The object of investigation is formulation of the comparative karyological characteristic of the family of chironomides and midges and determination of the tendency of evolution of the karyotypes thereof applications of the obtained data for the taxonomy of these families. The researchers have carried out an analysis of the cytological polymorphism and determined the relationship between the processes of adaptation and speciation. The cytophotocharts representing polytene chromosomes of eighty eight species of chironomides and midges and table allow identifying the larvae of these species, particularly twin species. The data contained in the dissertation are included in the lecture course at the St.-Petersburg and the Moscow State University and employed in the development of new methods of prediction of the status of the aqueous ecological systems exposed to anthropogenic effectsAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Polytene chromosomes of Chironomidae (Diptera) as a bioassay of trace-metal-induced genome instability

Chironomids are a ubiquitous group of aquatic insects that are very sensitive to environmental stress. Due to the presence of polytene (‘giant’) salivary gland chromosomes, it is possible to define the genome response of several Chironomid species to various stress agents. The aim of this study was to assess the genotoxic changes in populations of widely distributed chironomid species from aquatic basins in Bulgaria, Italy, Russia, U.K. and Poland, which were exposed to high concentrations of trace metals. We analyzed the structural and functional alterations of polytene chromosomes of the salivary glands of larvae belonging to three different cytocomplexes of the genus Chironomus (“thummi”, “lacunarius”, “pseudothummi”), and genera Glyptotendipes and Kiefferulus. Somatic structural chromosome rearrangements (para- and pericentric heterozygous inversions, deletions, deficiencies and amplifications) were used to estimate a Somatic index (S) for each population. The highest S indexes were detected in Chironomus riparius populations from locations with high concentrations of trace metals in the sediment. Each species showed specific genome responses to stress agents which we discussed in the light of the specific DNA structures and cytogenetic characteristics of the species. In larvae from polluted sediments two key structures of the salivary gland chromosomes (Balbiani Rings and Nucleolar Organizer) sharply reduced their activity to levels below those observed under non-polluted conditions. It is concluded that polytene chromosomes can be used as tools for evaluating the genotoxicity of the aquatic environment. Structural and functional chromosome alterations provide cost-effective early-warning signals of genotoxic concentrations of environmental pollutants. doi: 10.5324/fn.v31i0.1355. Published online: 17 October 2012

In Memoriam: Professor Iya Kiknadze (1930–2017)

Volume: 12Start Page: 141End Page: 14

A new record of Chironomus (Chironomus) acidophilus Keyl (Diptera, Chironomidae) from the Uzon volcanic caldera (Kronotsky Reserve, Kamchatka Peninsula, Russia), its karyotype, ecology and biology

Orel, Oksana V., Lobkova, Ludmila E., Zhirov, Sergey V., Petrova, Ninel A. (2015): A new record of Chironomus (Chironomus) acidophilus Keyl (Diptera, Chironomidae) from the Uzon volcanic caldera (Kronotsky Reserve, Kamchatka Peninsula, Russia), its karyotype, ecology and biology. Zootaxa 3981 (2): 177-192, DOI: 10.11646/zootaxa.3981.2.

A new record of Chironomus (Chironomus) acidophilus Keyl (Diptera, Chironomidae) from the Uzon volcanic caldera (Kronotsky Reserve, Kamchatka Peninsula, Russia), its karyotype, ecology and biology

Orel, Oksana V., Lobkova, Ludmila E., Zhirov, Sergey V., Petrova, Ninel A. (2015): A new record of Chironomus (Chironomus) acidophilus Keyl (Diptera, Chironomidae) from the Uzon volcanic caldera (Kronotsky Reserve, Kamchatka Peninsula, Russia), its karyotype, ecology and biology. Zootaxa 3981 (2): 177-192, DOI: http://dx.doi.org/10.11646/zootaxa.3981.2.