Mitotic chromosomal abnormalities and DNA polymorphism in the Nile tilapia (Oreochromis niloticus,Linnaeus, 1758) as a biomarker for water pollution by heavy metals

Mitotic chromosomal aberrations and DNA polymorphism (RAPD marker) were carried out on the Nile tilapia Oreochromis niloticus collected from five sites in Minia governorate, Egypt to test their applicability as biomonitors for heavy metal contaminants of water. The diploid chromosome number of O. niloticus population was 2 n = 44. Different types of chromosomal aberrations were recorded (e.g., deletion, ring, centromeric attenuation, end-to-end association, dicentric chromosome, stickiness chromosomes, endomitosis, fragments and chromatid gap). The chromosomal aberrations varied between O. niloticus population collected from five sites, and the most common type was ring (R) chromosomes. Samples obtained from Bahr Yousef and Irrigation drain exhibited the highest aberration frequency. The frequency of chromosomal aberration was positively correlated with the concentration of heavy metals where their concentration in the surface water of Irrigation drain and Bahr Yousef exceeded the limits defined by WHO as well as the concentration of Pb in muscles. The RAPD marker was also used to identify genetic variation among Nile tilapia samples collected from five different water sources. It created polymorphic and unique bands that can be used as genetic markers to track DNA variations. The dendrogram also revealed that exposure to heavy metal pollution causes gradual accumulation of variance, whereas areas subjected to environmental stress showed higher genetic variation and clustered together.     

Chromosome aberrations in peripheral blood lymphocytes of individuals living in high background radiation areas of Ramsar,Iran

In order to investigate the biological effects of exposure to low-dose radiation and to assess the dose–effect relationship in residents of high background radiation areas (HBRAs) of Ramsar, cytogenetic investigation of unstable-type aberrations was performed in 15 healthy elderly women in a HBRA of Ramsar, Talesh mahalle, and in 10 elderly women living in a nearby control area with normal background radiation. In total, 77,714 cells were analyzed; 48,819 cells in HBRA residents and 28,895 cells in controls. On average, 3,108 cells per subject were analyzed (range 1,475–5,007 cells). Significant differences were found in the frequency of dicentric plus centric rings in 100 cells (0.207 ± 0.103 vs. 0.047 ± 0.027, p < 0.0005), total chromosome-type aberrations per 100 cells (0.86 ± 0.44 vs. 0.23 ± 0.17, p < 0.0005), and chromatid-type aberrations per 100 cells (3.31 ± 2.01 vs. 1.66 ± 0.63, p = 0.01) by the Mann–Whitney U test between HBRA and the control, respectively. Using chromosomal aberrations as the main endpoint to assess the dose–effect relationship in residents of HBRAs in Ramsar, no positive correlation was found between the frequency of dicentric plus centric ring aberrations and the cumulative dose of the inhabitants estimated by direct individual dosimetry; however, obvious trends of increase with age appeared in the control group. Based on these results, individuals residing in HBRAs of Ramsar have an increased frequency of detectable abnormalities in unstable aberrations.     

Toxicological Assessment of Arsenic-Induced Hematological Alterations and Chromosomal Aberrations in Tilapia Oreochromis mossambicus

Arsenic is an environmental contaminant and potential carcinogen. Toxicological assessment of As, which causes hematological alterations and chromosomal aberrations, was studied in freshwater fish Oreochromis mossambicus. Fish were exposed to 3 ppm, 28 ppm, and 56 ppm concentrations of sodium arsenite (NaAsO₂) and blood samples were collected after 48 h, 96 h, and 192 h of exposure. Hematological assay of exposed fish revealed abnormal mature and immature erythrocytes, deformed erythrocytes (spindle-shaped and triangular erythrocytes) and erythrocytes with segmented nuclei in all treatments. Arsenic exposure induced chromosomal aberration in a concentration-dependent manner, whereas, a decreasing trend was found after 192 h exposure. Observations on blood cells of exposed fish revealed chromosome breaks, chromatid breaks, and chromatid gaps. The alterations and aberrations of these parameters can be effectively used to assess toxicological effects of As on fish in the aquatic environment and at the same time this study elucidates the potential risks to humans who live in arsenic-contaminated areas.     

The influence of DNA content and nuclear volume on the frequency of radiation-induced chromosome aberrations in Bufo species

The frequency of chromosome aberrations was compared in X-irradiated blood lymphocytes of Bufo marinus, B. calamita and B. pardalis which have similar chromosome numbers (2n=22) and karyotypes but differ in chromosomal DNA content and nuclear volume. — For each species the yield, per cell of centric exchange aberrations (dicentrics+rings) and of deletions (interstitial and terminal) increased approximately as the 1.5th power of the dose. — The 55% higher chromosomal DNA content of B. pardalis compared with both B. marinus and B. calamita resulted in the same increase in the frequency of deletions as a 55% increase in radiation dose, approximately doubling the yield. Both factors probably lead to a similar increase in the frequency of primary lesions from which the deletions are derived. — In contrast, an increase in chromosomal DNA content did not result in a higher yield of dicentric and ring exchanges, probably because the greater nuclear volume of B. pardalis (twice that of the other species) offset the potential increase in exchanges by increasing the average distance between chromosomes and chromosome arms. The data support the hypothesis that, in order to be involved in exchange, chromosome regions must be close together at the time of irradiation. The frequency of deletions is unaffected by changes in nuclear volume.     

Radiation-induced chromosomal aberrations in the bone marrow of mice exposed to various doses of gamma radiation

The occurrence of chromosomal aberrations was studied at 1–14 days post-exposure in female BALB/c mice exposed to various doses of gamma radiation. The frequency of abnormal cells, chromatid and chromosome breaks, dicentrics, centric rings, acentric fragments and total aberrations increased with exposure dose, and it was highest at 7 Gy. A peak was recorded on day 1 post-exposure with a gradual decline thereafter. The chromosomal aberration yield reached a nadir on day 14 post-irradiation, without restoration to the control level. The best fit for the present data was by a linear-quadratic relationship between dose of radiation and the frequency of chromosomal aberrations.     

Influence of mitotic delay on the results of biological dosimetry for high doses of ionizing radiation

The purpose of this study was to systematically investigate how high doses of sparsely and densely ionizing radiations influence the proliferation time of lymphocytes in short-term cultures and, consequently, the observed frequencies of dicentric and centric ring chromosomes. Peripheral blood samples from five volunteers were irradiated with high doses of 200 kV X-rays and with neutrons with a mean energy of <E _n>=2.1 MeV. First division metaphase cells were collected after different culture times of 48, 56, and 72 h and dicentrics, centric ring chromosomes, and acentric fragments were determined. The data hint at considerable mitotic delay. The main increase in the number of chromosome aberrations occurred between 48 and 72 h after an X-ray exposure and between 56 and 72 h after neutron exposure. When the data were used for a calibration of aberration frequency versus dose, subsequent dose estimations resulted, however, in comparable values. Thus, in spite of the influence of mitotic delay on observable chromosome aberrations, at least for the radiation types investigated here, a culture time of 48 h is acceptable for biological dosimetry.     

High diversity of centric fusions with monobrachial homology in an area of chromosomal polymorphism of Mus musculus domesticus

One of the simplest models of chromosomal speciation is speciation by monobrachial centric fusion. This model is based on the assumption that a sterility barrier can develop between populations, in which fixed centric fusions show monobrachial homology, i.e. share only one chromosome arm. However, studies aimed at delineating intermediate stages of transition to reproductive isolation are lacking. In this paper, we describe a new area of chromosomal polymorphism in the house mouse, Mus musculus domesticus Schwarz and Schwarx, 1943, in Sicily (Italy). We trapped 79 mice at eighteen localities in an area of approximately 500 Km² surrounding the largest active European volcano, Mount Etna. Combining G‐banding and chromosome painting we identified twelve different Robertsonian (Rb) metacentrics. Considering the high number of Rb fusions, some of them shared with other documented areas, the presently studied area of chromosomal polymorphism is very likely to represent a mixture of allochthonous and autochthonous Rb fusions. The Rb(9.16) is the most widespread metacentric (overall frequency 0.80). Two Rb metacentrics, Rb(4.10) and Rb(5.6), have similar overall frequency, 0.29 and 0.37, respectively, and are narrowly co‐distributed in ten populations. Nine fusions – Rb(2.13), Rb(1.3), Rb(12.17), Rb(8.17), Rb(2.14), Rb(10.14), Rb(11.17), Rb(3.15), and Rb(11.14) – show a low frequency (0.04–0.01) and mostly non‐overlapping localization, but each of them shares monobrachial homology with at least one other metacentric. The overall geographical distribution of different Rb fusions seems to match an early stage of race formation. The eventual role of the presently studied hybrid zone in the context of chromosomal speciation by monobrachial centric fusions is discussed. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 722–731.     

Isolation of 24-epibrassinolide from leaves of <Emphasis Type="Italic">Aegle marmelos</Emphasis> and evaluation of its antigenotoxicity employing <Emphasis Type="Italic">Allium cepa</Emphasis> chromosomal aberration assay

Brassinosteroids are of universal occurrence in plants. They have been reported to affect plant growth and development through a spectrum of physiological responses. Recently they are reported to confer resistance in plants against a number of biotic and abiotic stresses. In the present study, a brassinosteroid was isolated from Aegle marmelos Correa. (Rutaceae) which was characterized to be 24-epibrassinolide (EBL) using various spectroscopic techniques (TLC and ESI-MS analysis). It was evaluated for the antigenotoxicity against maleic hydrazide (MH) induced genotoxicity in Allium cepa chromosomal aberration assay. It was shown that the percentage of chromosomal aberrations induced by maleic hydrazide (0.01%) declined significantly with 24-epibrassinolide treatment. EBL (10⁻⁷ M) proved to be the most effective concentration with 91.8% inhibition. This is the first report on the isolation of 24-epibrassinolide from Aegle marmelos and its antigenotoxic effects against MH employing Allium cepa chromosomal aberration assay.     

Cytologische und stoffwechselphysiologische Untersuchungen am aktiven Meristem der Wurzelspitze von Vicia faba L

Summary Seeds ofVicia faba L. var.minor (2n=12) were submerged in tap water for 12 to 96 hours. After submersion and recovery times of 48 to 144 hours root tips were fixed in intervals of 24 hours. The presoaking of seeds before germination led to an increase of the spontaneous chromosomal aberration rate. Up to 65% of all cells in the root tips showed fragments, chromatid-translocations and triradials after 72 hours of presoaking and up to 12% of all chromosomes showed breaks or participated in chromatidal reunions. Submersion of seeds for 12 hours already caused a statistically significant increase of chromosomal aberrations in comparison to the controls. The maximum of aberrations was found after a recovery period of 120 hours, afterwards the aberration rate dropped. Parallel experiments with the N₂-atmosphere showed that the increase in aberration rate is caused by metabolic changes produced by anaerobiosis. Probably the changed metabolic conditions led to the formation of automutagenic substances. The distribution of breaks between the mand SAT-chromosomes was not at random (theoretical expectation 5∶2); more breaks appeared in the mthan in the SAT chromosomes (actual relation 5∶1,1). The breaks in the mand SAT chromosomes were localized in a few special regions.      

Characteristics of γ-ray-induced chromosomal aberrations in mutagen-sensitive mutants of L5178Y cells

We have examined the chromosomal radiosensitivities of an ionizing-radiation- and MMS-sensitive mutant (M10), and a UV- and 4NQO-sensitive mutant (Q31), isolated from mouse lymphoma L5178Y cells, with regard to killing effects. In the first mitoses after 100 R γ-irradiations, it was found that M10 cells were highly radiosensitive in terms of chromosomal aberrations accompanying longer mitotic delay (3 h); the frequencies of both chromatid-type and chromosome-type aberrations were, respectively, about 7 and 4 times higher than that of wild-type L5178Y cells. Furthermore, chromatid exchanges, particularly triradials, isochromatid breaks with sister union, and chromatid gaps and breaks were markedly enhanced at G₁ phase of M10 cells. In contrast, the chromosomal radiosensitivity of Q31 cells after 100 R irradiation was similar to that of L5178Y cells. On the other hand, spontaneous aberration frequencies (overall breaks per cell) of M10 and Q31 cells were, respectively, 5.1 and 2.2 times higher than that of wild-type L5178Y cells. The chromosomal hypersensitivity to γ-rays in M10 cells is discussed in the light of knowledge obtained from ataxia telangiectasia cells.     

The localisation of radiation induced chromosome aberrations in relation to the distribution of heterochromatin in Secale cereale

The distribution of two break chromosome exchanges (dicentrics and centric rings) following gamma or neutron irradiation of resting seeds of rye, Secale cereale, has been investigated. The localisation of heterochromatin in the terminal ends of the chromosomes of rye facilitates distinguishing aberrations involving heterochromatin from others. Dicentrics found in or near heterochromatic regions were about 5 times more frequent after gamma irradiation and about 2.5 times more after neutron irradiation, than expected on a random distribution. The implications of these findings in relation to aberration formation are discussed.     

The genetics and cytology of a mutator factor in Drosophila melanogaster

A Drosophila melanogaster mutator factor is described whose effects include the induction of unique chromosomal aberrations and male crossing over. Results of experiments to map the factor suggest that genetic transmission is somehow chromosomally associated but not localizable to the X, Y, second or third chromosome. There appears to be a good correlation between the distributions of male crossover exchange points and unique aberration breakpoints for the second chromosome but not for the third chromosome. The male crossovers, which occur more frequently in the centromeric region, occur in euchromatin rather than in the centric heterochromatin. The male crossovers tend to be rather precise reciprocal exchanges, since cytologically detectable deletions and duplications are only infrequently produced. It is suggested that the present mutator may be identical to earlier reported mutators of D. melanogaster.     

Prokaryotic and eukaryotic community structure affected by the presence of an acid mine drainage from an abandoned gold mine

The acid mine drainage that originates in the abandoned gold mine in San Luis, Argentina, is released into La Carolina stream. The aim of this study was to determine the influence of this mine drainage on the physicochemical parameters of the area studied and on both prokaryotic and eukaryotic community structure. In addition, specific relationships between microbial taxonomic groups and physicochemical parameters were established. The drainage that flows into La Carolina stream acidifies the stream and increases its sulfate, Zn, Cd and Te concentrations. Microbial analysis showed that prokaryotic community structure is mainly affected by pH values. Actinobacteria and Gammaproteobacteria were abundant in samples characterized by low pH values, while Nitrospirae, Chloroflexi, Deltaproteobacteria, Thaumarchaeota and Euryarchaeota were associated with high concentrations of heavy metals. Otherwise, Alphaproteobacteria was present in samples taken in sunlit areas. Regarding eukaryotic community structure, the sunlight had the greatest impact. Inside the mine, in the absence of light, fungi and protists members were the most abundant microorganisms, while those samples taken in the presence of light displayed algae (green algae and diatoms) as the most abundant ones. After receiving the mine drainage, the stream showed a decrease in the diatom abundance and green algae predominated.

     

Significato dei Tegumenti in Cariossidi di Triticum Durum Desf. Trattate Con Raggi X

Abstract

Significance of integuments in caryopses of « Triticum durum » Desf. treated with X-rays. Experiments were carried out on Triticum durum « Cappelli », to test the influence of seed coats on the damage by X-rays. The damage was evaluated in terms of germination, seedling growth and chromosomal aberrations. Seeds in which the embryo was covered (with pericarp and spermoderm), uncovered (without pericarp) and bared (without pericarp and spermoderm), were irradiated at the total exposure of 1000, 2000 and 4000 R of X-rays. The growth of seedlings coming from covered and uncovered embryos, X-rayed at 1000 R, results better than that of bared embryos. The chromosomal aberrations analysis carried out in root meristem cells at anaphase, during the first mitotic cycle, show the highest damage in seedlings coming from uncovered and bared embryos and the type of aberrations was almost chromatidic (B'). We therefore forward the hypothesis that the removal of the integuments (pericarp and spermoderm) could possibly accelerate the process of germination, and could also produce in the embryo a greater sensitivity to X-rays.     

频繁使用染发剂对小鼠染色体畸变率影响的研究

研究了多次接触７ 种染发剂对不同组小鼠骨髓和生殖细胞染色体畸变率的影响。结果发现, ７ 种染发剂均导致出现较高的染色体畸变率,３ 种能引起小鼠骨髓细胞染色体畸变率显著上升, 其中以粉末状染发剂的影响最为严重。４ 种染发剂对进行生殖细胞染色体畸变实验的小鼠均产生显著影响, 尤以氧化型染发剂最为明显。     

Chromosomal aberrations in Japanese grass voles in and around an illegal dumpsite at the Aomori-Iwate prefectural boundary

Bone marrow chromosomes of thirty specimens of the Japanese grass vole, Microtus montebelli (2n=30), which had been caught on and near an illegal dumpsite at the Aomori-Iwate prefectural boundary, were analyzed and compared with those of fifteen grass voles from non-polluted areas as part of an effort to assess genotoxic influences on grass voles in the dumpsite area. Fifty metaphases per specimen were examined with particular attention to numerical and structural aberrations. Two specimens from the dumpsite had 2n=31, which was confirmed by G-banding analysis to have been caused by centric fission of M6 homologs, while control specimens had no such abnormality. In specimens from the polluted area, the mean number of chromosomal aberrations (breaks and/or gaps) per 50 metaphases per specimen was 2.57+/-0.41, which was significantly higher than that (0.80+/-0.14; P<0.01) in control specimens. Chromosomal aberrations were randomly distributed on chromosomes, with frequencies being proportional to the relative lengths of chromosomes. Our findings suggest that grass voles at and around the dumpsite have been seriously damaged at the chromosomal level and, moreover, that M. montebelli might be useful as an indicator species for genotoxic assessment of below-ground pollution by industrial waste at illegal dumpsites.     

Genotoxic studies in hypertensive and normotensive rats treated with amiodarone

Amiodarone, a benzofuran derivative, is a very effective antiarrhythmic medication, but has potential to cause side effects. Although its cytotoxicity potential is very well-known, there are few reports about its genotoxicity effects. Since amiodarone has not been investigated in genotoxicity studies, and the spontaneously hypertensive rat (SHR) is a well-characterized model for hypertension, the aim of the present study was to perform cytogenetic analysis on chromosome aberrations in bone marrow cells of SHRs and normotensive Wistar-Kyoto rats (WKYs) that received oral amiodarone treatment for 4 weeks. Amiodarone activity was also monitored using electrocardiograms. The presence of bradycardia in amiodarone-treated rats confirmed that this drug was really active. Metaphase analysis on bone marrow cells showed that there were significant differences in total chromosomal damage and percentage abnormal metaphase between WKY and SHR negative controls. In the SHR negative control, the frequencies of basal chromosomal aberrations and abnormal metaphases were significantly higher (p < 0.05). There were high numbers of chromosomal aberrations in all amiodarone-treated groups, compared with negative controls. In amiodarone-treated groups, the most frequent chromosomal aberration was chromatid breaks. More chromosomal aberrations were found in WKYs that received amiodarone, with a statistically significant difference in comparison with negative controls (p < 0.05). However, in SHR rats there was no significant difference between the amiodarone and negative groups regarding chromosomal damage induction. These results showed that treatment with amiodarone was genotoxic in WKYs, but not in SHRs. Further studies are needed to confirm whether amiodarone is genotoxic or efficient and harmless, among humans undergoing therapy.     

Chromosomal aberrations and deoxyribonucleic acid single-strand breaks in adipose-derived stem cells during long-term expansion in vitro

Background aimsAdipose-derived stem cells (ASCs) are a promising mesenchymal cell source for tissue engineering approaches. To obtain an adequate cell amount, in vitro expansion of the cells may be required in some cases. To monitor potential contraindications for therapeutic applications in humans, DNA strand breaks and chromosomal aberrations in ASCs during in vitro expansion were examined.MethodsAfter isolation of ASC from human lipoaspirates of seven patients, in vitro expansion over 10 passages was performed. Cells from passages 1, 2, 3, 5 and 10 were used for the alkaline single-cell microgel electrophoresis (comet) assay to detect DNA single-strand breaks and alkali labile as well as incomplete excision repair sites. Chromosomal changes were examined by means of the chromosomal aberration test.ResultsDuring in vitro expansion, ASC showed no DNA single-strand breaks in the comet assay. With the chromosomal aberration test, however, a significant increase in chromosomal aberrations were detected.ConclusionsThe study showed that although no DNA fragmentation could be determined, the safety of ASC cannot be ensured with respect to chromosome stability during in vitro expansion. Thus, reliable analyses for detecting ASC populations, which accumulate chromosomal aberrations or even undergo malignant transformation during extensive in vitro expansion, must be implemented as part of the safety evaluation of these cells for stem cell–based therapy.     

DNA lesions and cytogenetic changes induced by N-nitrosomorpholine in HepG2, V79 and VH10 cells: the protective effects of Vitamins A, C and E

Introduction: N-Nitrosomorpholine (NMOR), present in the workplace of tyre chemical factories, is a known hepatocarcinogen. This compound belongs to the group of N-nitrosamines, which are indirect-acting and require metabolic activation. However, the mechanism of its carcinogenic effect is not completely clear. Aims: The objective of this study was (i) to compare the DNA-damaging and clastogenic effects of NMOR in three cell lines (HepG2, V79 and VH10) with different levels of metabolizing enzymes and (ii) to determine the protective effects of Vitamins A, C and E against deleterious effects of NMOR. Methods: The exponentially growing cells were pre-treated with Vitamins A, C and E and treated with NMOR. Genotoxic effects of NMOR were evaluated by single-cell gel electrophoresis (SCGE, comet assay), while the chromosomal aberration assay was used for the study of clastogenic effects. Key results: NMOR-induced a significant dose-dependent increase of DNA damage as analyzed by SCGE, but the extent of DNA migration in the electric field was unequal in the different cell lines. Although the results obtained by SCGE confirmed the genotoxicity of NMOR in all cell lines studied, the number of chromosomal aberrations was significantly increased only in HepG2 and V79 cells, while no changes were observed in VH10 cells. In HepG2 cells pre-treated with Vitamins A, C and E we found a significant decrease of the percentage of tail DNA induced by NMOR. The reduction of the clastogenic effects of NMOR was observed only after pretreatment with Vitamins A and E; Vitamin C did not alter the frequency of NMOR-induced chromosomal aberrations under the experimental conditions of this study. Conclusions: The fat-soluble Vitamins A and E, which are dietary constituents, reduce the harmful effects of N-nitrosomorpholine in human hepatoma cells HepG2, which are endowed with the maximal capacity for metabolic activation of several drugs.