B chromosome polymorphism of blackflies (Diptera, Simuliidae) from the north-western region of Russia

We have studied karyofonds of natural populations and B-chromosome morphology of 8 species of blackflies from the North-Western region of Russia: Odagmia ornata Mg., Hellichiella crassa Rubz., Simulium morsitans Edw., Simulium argyreatum Mg., Shoenbaueria pusilla Fries., Cnetha fontinalis Radzv., Stegopterna duo-decimata Rubz., and Archesimulium tuberosum Lundstr. For this purpose we made slides of squashed blackflies larvae with salivary gland polytene chromosomes stained by aceto-orcein, in addition to similarly stained slides with mitotic chromosomes from gonads and ganglia. Morphology of polytene B-chromosomes of Shoenbaueria pusilla Fries., Cnetha fontinalis Radzv., Stegopterna duodecimata Rubz., and Archesimulium tuberosum Lundstr. has been first described. B-chromosome polymorphism was found in all species, but the number of B chromosomes was conserved within each differences in polytene individual. Stable and distinct interspecific differences in the morphology of polytene B-chromosomes were demonstrated, and these characters are advisable to use to distinguish the species. We have investigated for the first time karyofonds of Od. ornata populations from Arkhangelsk Region (Solovetskie Islands) and Leningrad Region (railway station Sablino), and those of S. argyreatum populations from Murmansk Region (Kandalaksha environs) and Karelia (railway station Chupa). A long term study of Od. ornata and S. argyrestum population from North-Western Russia revealed interspecific and interpopulation dynamics of the occurrence of specimens with B-chromosomes. Some populations showed an increased percentage of individuals with B-chromosomes. It is suggested that B-chromosomes may play a role in adaptation of polulations to severe environmental conditions.     

Population structure and hypothetic pathways of differentiation of whitefishes (<Emphasis Type="Italic">Coregonus lavaretus pidschian</Emphasis>, Coregonidae) in the Dodot lakes (the Khamsara River upstream)

We have studied morphology and ecology of whitefish Coregonus lavaretus pidschian (Gmelin) inhabits the Dodot lakes (Aldy-Deerlig-Khol and Ustyu-Deerlig-Khol) situated in the upstream of the Khamsara River (the Bolshoi Yenisei River basin, Tyva Region). The whitefishes were represented by lacustrine and river populations occupying similar ecological niches. We found significant differences in the perforated lateral-line scale numbers between populations. In conclusion, we suggest that this region is the secondary contact zone.     

Polymorphism of the Noncoding Region of the Mitochondrial Genome in Three Kazakh Populations Inhabiting Different Areas of Kazakhstan and in DNA Samples from Ancient Populations of the Kazakhstani Altai

The polymorphism of the major noncoding region of mitochondrial DNA (mtDNA D loop, 528 bp) has been studied in samples from three modern Kazakh populations (from Almaty, the Semipalatinsk Region, and the Altai Mountains) and in DNA samples of ancient human populations of the Kazakhstani Altai. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis for 13 restriction sites, including BamHI, EcoRV, Sau3AI (one site each), KpnI (two sites), HaeIII (three sites), and RsaI (five sites) were used. The frequency distributions of all sites have been determined. The gene diversity (h) and the genetic distances between different Kazakh populations and other populations of the world have been calculated. The RFLP analysis of the mtDNA control region of fossil samples has been performed similarly to the analysis of modern mtDNA samples. Two fossil mtDNA samples from burial mound 11 are monomorphic with respect to all restriction sites analyzed.     

Duration of the mitotic cycle and radiosensitivity of chromosomes in human lymphocytes

The frequency of chromosome aberrations was studied in human lymphocytes, with different duration of the mitotic cycle (from 48 to 73 h), exposed to gamma-quanta 2 h before fixation (i. e. at the G2 stage). In all cases both the types and the frequencies of aberrations were the same; this was an argument against the assumption about the existence of populations varying by radiosensitivity of chromosomes.     

Chromosomal instability parameters in the population affected by nuclear explosions at the Semipalatinsk nuclear test site

A population genetic survey of 149 persons who were born and have permanently lived in the contaminated zones of the Semipalatinsk region has been performed. A cytogenetic study has demonstrated that the frequency of aberrant cells is 1.7-3 times higher than control parameters. The total frequencies of chromosome aberrations are 3.43 +/- 0.48, 3.1 +/- 0.3, 1.8 +/- 0.2, and 1.15 +/- 0.17 aberrations per 100 cells in the populations of the extreme radiation risk (ERR), maximum radiation risk (MaxRR), minimum radiation risk (MinRR), and control zones, respectively. The high chromosome aberration rate in all three zones of radiation risk has been detected mainly due to radiation-induced chromosome markers, including paired fragments (1.2 +/- 0.2, 0.94 +/- 0.13, and 0.43 +/- 0.06 per 100 cells, respectively), dicentric and ring chromosomes (0.44 +/- 0.04, 0.45 +/- 0.07, and 0.11 +/- 0.02 per 100 cells, respectively), and stable chromosome aberrations (0.74 +/- 0.16, 0.8 +/- 0.1, and 0.63 +/- 0.13 per 100 cells, respectively). The qualitative spectra of the cytogenetic lesions observed in these groups indicate a mutagenic effect of ionizing radiation on chromosomes in the populations studied.     

Chromosomal Instability Parameters in the Population Affected by Nuclear Explosions at the Semipalatinsk Nuclear Test Site

A population genetic survey of 149 persons who were born and have permanently lived in the contaminated zones of the Semipalatinsk region has been performed. A cytogenetic study has demonstrated that the frequency of aberrant cells is 1.7–3 times higher than control parameters. The total frequencies of chromosome aberrations are 3.43 ± 0.48, 3.1 ± 0.3, 1.8 ± 0.2, and 1.15 ± 0.17 aberrations per 100 cells in the populations of the extreme radiation risk (ERR), maximum radiation risk (MaxRR), minimum radiation risk (MinRR), and control zones, respectively. The high chromosome aberration rate in all three zones of radiation risk has been detected mainly due to radiation-induced chromosome markers, including paired fragments (1.3 ± 0.2, 0.94 ± 0.13, and 0.43 ± 0.06 per 100 cells, respectively), dicentric and ring chromosomes (0.44 ± 0.04, 0.45 ± 0.07, and 0.11 ± 0.02 per 100 cells, respectively), and stable chromosome aberrations (0.74 ± 0.16, 0.8 ± 0.1, and 0.63 ± 0.13 per 100 cells, respectively). The qualitative spectra of the cytogenetic lesions observed in these groups indicate a mutagenic effect of ionizing radiation on chromosomes in the populations studied.     

Critical periods of the mitotic cycle: influence of aminopterin and thymidine on production of chromosomal aberrations by radiation in Crepis capillaris.

The influence of aminopterin (AP), tritiated thymidine ([3H] TdR) and "cold" thymidine (TdR) on production of chromosomal aberrations in meristematic cells of Crepis capillaris irradiated in different stages of the mitotic cycle with 300 rad of 63Co gamma-rays was studied. All the chemical treatments increased most of all the frequency of aberrations induced during two "critical periods" localized before the stage of DNA synthesis (fixation 9 h after irradiation) and before that of mitosis (4 h). Treatments with TdR and [3H]TdR increased most of all the frequency of chromatid aberrations when irradiation was performed in G1, and the frequency of gaps when irradiated in G2. Treatment with AP increased the yield of different types of aberration more uniformly. The modifying effect of the chemicals tested appeared to be independent of replicative synthesis. The "critical periods" are suggested to be the stages when regular "proof reading" and correction of spontaneous errors takes place [9,13]. In addition to this regular mechanism, radiation induces an "emergency" mechanism of repair. AP inhibits the mechanism of regular repair; in addition TdR and [3H] TdR suppress the lateral spread of primary injuries across the chromosome.     

Number of aberrations per cell as a parameter of chromosome instability. 2. Comparative analysis of the factors of different nature

The average number of aberrations per aberrant cell was concluded to carry out information on chromosome instability peculiarities induced by different mutagens as it was shown in our previous work. The purpose of the current study was to present comparative analysis of intercellular distribution of number of aberrations and their theoretical approximations. Distribution of numbers of aberrations per cell in Allium cepa L. and Allium fistulosum L. root tip cells induced by different mutagenic factors (gamma-irradiation, thiotepa, formaldehyde and seed aging) have been studied. The results were approximated to theoretical Poisson, geometric and negative binomial distributions. The intercellular distribution of aberrations did not correspond to any of the used theoretical distributions when A. cepa seeds were gamma-irradiated. There was some, but not regular, accordance with theoretical distributions when chemical mutagens thiotepa in A. cepa and formaldehyde in A. fistulosum and seed aging in both species were evaluated. During seed aging frequency of aberrant cells increased more quickly in A. fistulosum in comparison with A. cepa.     

Shell chirality in Cambrian gastropods and sinistral members of the genus <Emphasis Type="Italic">Aldanella</Emphasis> Vostokova, 1962

Shell chirality among Cambrian gastropods is discussed. It is demonstrated that the earliest members of the class include chiral aberrations with abnormal opposite coiling of the shell. It is assumed that, in Cambrian gastropods, speciation could have occurred by mutation in the locus determining the chirality, as is proposed for extant gastropods. In contrast to modern gastropods, the existence of chiral morphs within single species has not been recorded in Cambrian mollusks, whereas the presence of chiral twin species is possible. The systematic position of sinistral representatives of the genus Aldanella Vostokova, 1962 is considered. Aldanella golubevi sp. nov. with sinistral shell is described from the base of the Tommotian Stage of the Anabar Region. Aberrant sinistral specimens of the normally dextral species Aldanella utchurica Missarzhevsky in Rozanov et al., 1969 and Pelagiella adunca Missarzhevsky in Rozanov et al., 1969 are figured.     

Monomorphism of isozyme loci in natural and cultivated amaranth (<Emphasis Type="Italic">Amaranthus</Emphasis> L.) populations

Electrophoretic spectra of alcohol dehydrogenase (ADH), glutamate dehydrogenase (GDH), malate dehydrogenase (MDH), isocitrate dehydrogenase (IDH), and malic enzyme (ME) in different amaranth populations has been studied using a starch gel electrophoresis. 93 populations and 4 cultivars of amaranth have been analyzed. Some populations have been proved to be polymorphic that provided a possibility of a genetic control of the above-mentioned enzymes. The isozyme variability of the studied amaranth populations is low; all studied loci are found to be monomorphic for 73 populations and 4 cultivars. Some populations demonstrate a polymorphism in separate loci (Adh, Mdh 2, Gdh, Idh 1, Idh 2, and Mod 2). The obtained results evidence the presence of a genetic monomorphism in amaranth concerning the loci studied.     

Risks of endemicity, morbidity and perspectives regarding the control of Chagas disease in the Amazon Region

Chagas disease, in the Amazon Region as elsewhere, can be considered an enzootic disease of wild animals or an anthropozoonosis, an accidental disease of humans that is acquired when humans penetrate a wild ecosystem or when wild triatomines invade human dwellings attracted by light or searching for human blood. The risk of endemic Chagas disease in the Amazon Region is associated with the following phenomena: (i) extensive deforestation associated with the displacement of wild mammals, which are the normal sources of blood for triatomines, (ii) adaptation of wild triatomines to human dwellings due to the need for a new source of blood for feeding and (iii) uncontrolled migration of human populations and domestic animals that are already infected with Trypanosoma cruzi from areas endemic for Chagas disease to the Amazon Region. Several outbreaks of severe acute cases of Chagas disease, as well as chronic cases, have been described in the Amazon Region. Control measures targeted to avoiding endemic Chagas disease in the Amazon Region should be the following: improving health education in communities, training public health officials and communities for vector and Chagas disease surveillance and training local physicians to recognise and treat acute and chronic cases of Chagas diseases as soon as possible.     

Chromosomal DNA balance in human stem cell line 4BL

Ploidy of a chromosome set and some regular structural aberrations in the new human 4BL cell line by passage 205 have been characterized in the previous cytogenetic studies. The purpose of this study was to investigate, using the array CGH and FISH methods, the nature of regular monosomies in particular homologous pairs. Structural aberrations were detected in all the chromosome pairs distinguished as monosomies according to classical cytogenetic analyses. The most notable alterations have been detected in chromosomes 2, 4, 10, 13, and 17. Massive genetic material losses were a probable cause for the monosomy of chromosomes 4, 10, 13, and 17. The monosomy of the second pair of chromosomes was caused by a substantial transformation in one of the homologs typified as multiple duplications and the formation of a derivative—der(2)t(2;?)(q21;?). The application of array CGH aided us in identifying the regions of structural aberrations in chromosomes 2, 4, 10, 13, and 17, that allowed a more accurate identification with the use of the multicolor FISH method. The obtained results confirm the hypothesis concerning a coordinated emergence of deletions and duplications and their stabilizing effect on transformed chromosomes.     

Results of a cytogenetic study of populations with different radiation risks in the Semipalatinsk region

A cytogenetic study was conducted for the first time on human populations neighboring the Semipalatinsk nuclear test site (STS) and exposed to ionizing radiation for a long period of time. In populations with the extreme and maximum radiation risks, high frequencies of radiation-induced chromosomal markers, including acentric fragments (1.99 +/- 0.10 per 100 cells), dicentrics (0.23 +/- 0.01), ring chromosomes (0.38 +/- 0.14), and stable chromosomal aberrations (1.17 +/- 0.02), were found. These frequencies significantly exceeded those in control populations. The spectrum of chromosomal aberrations and the frequencies of the aberrations of different types in persons living in the areas with the highest radionuclide contamination confirmed the mutagenic effect of radiation on chromosomes in the human populations studied.     

A karyological study of swamp and dry valley populations of Siberian fir (<Emphasis Type="Italic">Abies sibirica</Emphasis> Ledeb.)

The karyological data on populations of Siberian fir (Abies sibirica Ledeb.) growing in lowland swamp and dry valleys are given. The diploid set of both populations included 24 chromosomes (2n = 24). Polykaryogram analysis revealed seven pairs of metacentric and five pairs of submetacentric chromosomes. The revealed differences between the populations included the absolute length of chromosomes, number of nucleolar organizer regions, and number of nucleoli. Changed chromosome numbers (mixoploidy and aneuploidy) as well as chromosomal aberrations were recorded. For the first time, mitosis was studied in this species and anaphase/telophase aberrations were revealed. The population of Siberian fir growing under extreme conditions of lowland swamp featured the widest range of mutations.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 1, 2005, pp. 23–29.Original Russian Text Copyright © 2005 by Sedelnikova, Pimenov.     

Effect of charged particles of relativistic energy on the number of chromosome aberrations in human blood lymphocytes. Dose-response relationship and the RBE of protons, deuterons and helium ions

In experiments with human blood lymphocyte culture exposed to fast protons, deuterons and helium ions the frequency and types of chromosome aberrations have been studied. Fast charged particles of a relativistic energy are shown to have a pronounced harmful effect resulting in a sharply increased formation of exchange chromosome aberrations as compared to that produced by gamma-radiation. The RBE coefficients of the particles under study have been determined: their values vary depending on the type of radiation and the tests used.     

Results of a Cytogenetic Study of Populations with Different Radiation Risks in the Semipalatinsk Region

A cytogenetic study was conducted for the first time on human populations neighboring the Semipalatinsk nuclear test site (STS) and exposed to ionizing radiation for a long period of time. In populations with the extreme and maximum radiation risks, high frequencies of radiation-induced chromosomal markers, including acentric fragments (1.99 ± 0.10 per 100 cells), dicentrics (0.23 ± 0.01), ring chromosomes (0.38 ± 0.14), and stable chromosomal aberrations (1.17 ± 0.02), were found. These frequencies significantly exceeded those in control populations. The spectrum of chromosomal aberrations and the frequencies of the aberrations of different types in persons living in the areas with the highest radionuclide contamination confirmed the mutagenic effect of radiation on chromosomes in the human populations studied.     

Cytogenetic monitoring of industrial populations potentially exposed to genotoxic chemicals and of control populations

Currently the most applied technique for monitoring biological effects of exposure to genotoxic chemicals in industrial workers is the measurement of chromosome aberrations in peripheral blood lymphocytes. In the Shell petrochemical complex in The Netherlands cytogenetic monitoring studies have been carried out from 1976 till 1981 inclusive, in workers potentially exposed to a variety of genotoxic chemicals, i.e. vinyl chloride, ethylene oxide, benzene, epichlorohydrin, epoxy resins. Average exposure levels to these chemicals were well below the occupational exposure limits. Results of these studies indicate that no biologically significant increase in the frequencies of chromosome aberrations in the exposed populations occurred compared with control populations. Our experience with this methodology has shown that the results of chromosome analyses are difficult to interpret, due to the variable and high background levels of chromosome aberrations in control populations and in individuals. It is concluded that the method is not sufficiently sensitive for routine monitoring of cytogenetic effects in workers exposed to the low levels of genotoxic compounds.     

Origins and Relationship of Cave Populations of the Blind Mexican Tetra, Astyanax Fasciatus, in the Sierra De El Abra

The blind morph of Astyanax fasciatus (Pisces: Characidae) has been more thoroughly studied than any other cave inhabiting organism. Most studies of A. fasciatus have used individuals from different caves of the Sierra de El Abra, Mexico, and have assumed that each population independently evolved to live in the cave environment. We analyzed the relationships among several cave populations that delineate the Sierra de El Abra using RAPD markers. The results indicate that all cave populations are more closely related to one another than they are to the surface populations. This suggests that present day cave populations derived from a common ancestral stock, most likely due to a single colonization event, or alternatively, that strong gene flow among cave populations has occurred, raising precaution against considering each cave population as independent.     

Gene mutations, chromosome aberrations and survival after the x-ray irradiation of a Chinese hamster cell culture protected by cysteamine

The protective effect of cysteamine against 6-thioguanine-resistance (TCr) mutations, chromosome aberrations and inactivation caused by X-ray in cultured cells of Chinese hamster (clone 431) has been studied. The dose-effect curves have been obtained under irradiation condition without protector and with it. Dose-modifying factor of 2 was calculated for chromosome aberrations and cells inactivation and 2,8 for TCr mutations. It is supposed that the cysteamine acts on the general mechanisms involved in damages realization which results in gene mutations, chromosome aberrations and cell inactivation.