Bimolane induces multiple types of chromosomal aberrations in human lymphocytes in vitro

Bimolane has been commonly used in China for the treatment of psoriasis and various types of cancer. Patients treated with bimolane have been reported to have an increased risk of developing therapy-related leukemias. Although bimolane has been identified as a human leukemia-inducing agent, little is known about its genotoxic effects, and a systematic study of the types of chromosomal alterations induced by this compound has not been performed. In this study, a combination of immunochemical, molecular and conventional cytogenetic techniques has been used to study the chromosomal alterations induced by bimolane in cultured human lymphocytes. Immunochemical staining with the CREST antibody indicated that bimolane induces micronuclei (MN) originating primarily from chromosome breakage. Interestingly fluorescence in situ hybridization (FISH) with differentially labeled chromosomes 1 and 9 centromeric probes indicated that bimolane also caused non-disjunction and polyploidy. Consistent with this, an expedited analysis of Giemsa-stained metaphase chromosomes in bimolane-treated lymphocytes revealed a high frequency of polyploidy/hyperdiploidy as well as dicentric chromosomes, and premature centromeric division (PCD). In addition, bimolane was also found to produce binucleated cells, possibly through an interference with normal functioning of intermediate filaments. As a follow-up to these studies, three different types of commercially available bimolane formulations obtained from different Chinese manufacturers were also evaluated. The effects seen with the formulated bimolane were similar to those seen with the synthesized compound. Our studies indicate that bimolane effectively induces a variety of cellular and chromosomal changes in cultured lymphocytes and that similar alterations occurring in bone marrow stem cells could contribute to the development of the secondary cancers seen in bimolane-treated patients.     

The cytotoxicity and genotoxicity of hexavalent chromium in Steller sea lion lung fibroblasts compared to human lung fibroblasts

In this study we directly compared soluble and particulate chromate cytotoxicity and genotoxicity in human (Homo sapiens) and sea lion (Eumetopias jubatus) lung fibroblasts. Our results show that hexavalent chromium induces increased cell death and chromosome damage in both human and sea lion cells with increasing intracellular chromium ion levels. The data further indicate that both sodium chromate and lead chromate are less cytotoxic and genotoxic to sea lion cells than human cells, based on an administered dose. Differences in chromium ion uptake explained some but not all of the reduced amounts of sodium chromate-induced cell death. By contrast, uptake differences could explain the differences in sodium chromate-induced chromosome damage and particulate chromate-induced toxicity. Altogether they indicate that while hexavalent chromium induces similar toxic effects in sea lion and human cells, there are different mechanisms underlying the toxic outcomes.     

Unscheduled DNA synthesis of rat hepatocytes in monolayer culture

Monolayer cultures of rat hepatocytes activated tris(2,3-dibromopropyl)phosphate (Tris-BP) more efficiently than 2-acetylaminofluorene (AAF), to genotoxic products which caused mutations in co-cultures of S. typhimurium. In contrast, AAF caused a greater genotoxic response in the hepatocytes than Tris-BP, as judged by the increase in DNA-repair synthesis measured by liquid scintillation counting of ³H-TdR incorporated into DNA isolated from the nuclei of the hepatocytes. Covalent binding of 0.05 mM ³H-Tris-BP to cellular proteins occurred at a similar rate as covalent binding of 0.25 mM ¹⁴C-AAF. Tris-BP was the more cytotoxic of the two compounds as determined by leakage of cellular lactate dehydrogenase into the culture medium. The observed differences in the cytotoxic and genotoxic responses between Tris-BP and AAF were probably caused by differences in the nature of their reactive metabolites with respect to stability, lipophilicity and/or their interactions with variuos cellular nucleophilic sites. The relative DNA-repair synthesis induced by an AAF exposure for 18 h decreased with time after plating of isolated hepatocytes. Tris-BP first caused an increase in the relative DNA-repair synthesis up to 27 h after plating, whereafter the response declined reaching control values using cultures 75 h after plating. In parallel with the decreased relative response in DNA-repair synthesis with time, the background radioactivity in isolated nuclei from untreated cells increased both when the hepatocytes were incubated in the presence or absence of hydroxyurea to inhibit replicative DNA synthesis. Increased DNA-repair synthesis was demonstrated as early as 3 h after commencing exposure to the test substances. While the induced DNA-repair synthesis caused by Tris-BP remained constant after 6 h of exposure, the response caused by AAF increased with increased exposure time beyond 6 h. To assess the role of different metabolic pathways in the genotoxic and cytotoxic responses of Tris-BP and AAF, the hepatocytes were exposed to test substances in the presence of various metabolic inhibitors for 3 h, whereafter the cell medium was removed and replaced by cell-culture medium containing ³H-TdR and hydroxyurea. The cytochrome P-450 inhibitor metyrapone decreased both the genotoxic and cytotoxic effects of Tris-BP, while α-naphthoflavone reduced the genotoxic effect of AAF. The addition of glutathione (GSH) or N-acetylcysteine decreased both the cytotoxic and genotoxic effects of Tris-BP, while cellular depletion of GSH by diethylmaleate increased these effects. Manipulations in the cellular levels of sulhydryl-containing substances in the hepatocytes by these agents had little effects on the DNA-repair synthesis caused by AAF. The results indicate that such a hepatocyte culture system may be very useful as a tool to study mechanisms involved in the formation of cytotoxic and/or genotoxic metabolites from various xenobiotics.     

Embryonic stem cells deficient for Brca2 or Blm exhibit divergent genotoxic profiles that support opposing activities during homologous recombination

The breast cancer susceptibility protein, Brca2 and the RecQ helicase, Blm (Bloom syndrome mutated) are tumor suppressors that maintain genome integrity, at least in part, through homologous recombination (HR). Brca2 facilitates HR by interacting with Rad51 in multiple regions, the BRC motifs encoded by exon 11 and a single domain encoded by exon 27; however, the exact importance of these regions is not fully understood. Blm also interacts with Rad51 and appears to suppress HR in most circumstances; however, its yeast homologue Sgs1 facilitates HR in response to some genotoxins. To better understand the biological importance of these two proteins, we performed a genotoxic screen on mouse embryonic stem (ES) cells impaired for either Brca2 or Blm to establish their genotoxic profiles (a cellular dose-response to a wide range of agents). This is the first side-by-side comparison of these two proteins in an identical genetic background. We compared cells deleted for Brca2 exon 27 to cells reduced for Blm expression and find that the Brca2- and Blm-impaired cells exhibit genotoxic profiles that reflect opposing activities during HR. Cells deleted for Brca2 exon 27 are hypersensitive to γ-radiation, streptonigrin, mitomycin C and camptothecin and mildly resistant to ICRF-193 which is similar to HR defective cells null for Rad54. By contrast, Blm-impaired cells are hypersensitive to ICRF-193, mildly resistant to camptothecin and mitomycin C and more strongly resistant to hydroxyurea. These divergent profiles support the notion that Brca2 and Blm perform opposing functions during HR in mouse ES cells.     

An investigation of effects of toluene and cigarette smoking on some blood parameters and lymphocyte life span

As toluene is an organic solvent, its cytotoxic effect on the cell is known. Similarly, it has been demonstrated that many of the chemical agents that enter the body through smoking have cytotoxic and genotoxic effects on the cells. In this study, the effects of these two toxic agents, both separately and in combination, on leukocyte counts, lymphocyte counts and mitotic index values were investigated. The study was carried out on blood samples of 100 males, divided into four groups: 25 non-smokers and 25 smokers, 25 toluene-exposed non-smokers and 25 no toluene-exposed smokers. The blood cell values of the blood samples were determined automatically on the hemogram apparatus. In addition slides of the blood samples were prepared according to the chromosome analysis procedure and the mitotic index values were determined through microscopy. The possible effects of smoking and toluene on lymphocyte life span was considered by correlating mitotic index values with lymphocyte counts in the same way for each of the subgroups. Results revealed that leukocyte counts and mitotic index values were higher in the smokers than the non-smokers whether or not they had been exposed to toluene. In addition the results indicate that lymphocyte life span may be shortened due to cigarette smoking and toluene exposure.     

Trisindoline synthesis and anticancer activity

Expression of a Rhodococcus-derived oxygenase gene in Escherichia coli yielded indigo metabolites with cytotoxic activity against cancer cells. Bioactivity-guided fractionation of these indigo metabolites led to the isolation of trisindoline as the agent responsible for the observed in vitro cytotoxic activity against cancer cells. While the cytotoxicity of etoposide, a common anticancer drug, was dramatically decreased in multidrug-resistant (MDR) cancer cells compared with treatment of parental cells, trisindoline was found to have similar cytotoxicity effects on both parental and MDR cell lines. In addition, the cytotoxic effects of trisindoline were resistant to P-glycoprotein overexpression, one of the most common mechanisms of drug resistance in cancer cells, supporting its use to kill MDR cancer cells.     

Comparison of cytotoxic and genotoxic effects of plutonium-239 alpha particles and mobile phone GSM 900 radiation in the Allium cepa test

The goal of this study was to compare the cytotoxic and genotoxic effects of plutonium-239 alpha particles and GSM 900 modulated mobile phone (model Sony Ericsson K550i) radiation in the Allium cepa test. Three groups of bulbs were exposed to mobile phone radiation during 0 (sham), 3 and 9 h. A positive control group was treated during 20 min with plutonium-239 alpha-radiation. Mitotic abnormalities, chromosome aberrations, micronuclei and mitotic index were analyzed. Exposure to alpha-radiation from plutonium-239 and exposure to modulated radiation from mobile phone during 3 and 9 h significantly increased the mitotic index. GSM 900 mobile phone radiation as well as alpha-radiation from plutonium-239 induced both clastogenic and aneugenic effects. However, the aneugenic activity of mobile phone radiation was more pronounced. After 9 h of exposure to mobile phone radiation, polyploid cells, three-groups metaphases, amitoses and some unspecified abnormalities were detected, which were not registered in the other experimental groups. Importantly, GSM 900 mobile phone radiation increased the mitotic index, the frequency of mitotic and chromosome abnormalities, and the micronucleus frequency in a time-dependent manner. Due to its sensitivity, the A. cepa test can be recommended as a useful cytogenetic assay to assess cytotoxic and genotoxic effects of radiofrequency electromagnetic fields.     

Sodium butyrate affects the cytotoxic and mutagenic response of V79 Chinese hamster cells to the genotoxic agents, daunorubicin and U.V. radiation

It has been suggested that conditions which lead to modifications in the chromatin structure could be responsible for an increased accessibility of DNA to genotoxic agents in eukaryotic cells. With this in mind, the cytotoxic and mutagenic activity of the anthracycline antibiotic, daunorubicin, and of UV radiation was assayed on V79 Chinese hamster cells pretreated or not with 5 mM sodium butyrate, an agent known to induce modifications in the chromatin structure: this treatment in fact proved to induce the hyperacetylation of the core histones, and moreover to enhance the cytotoxic response of the cells to both daunorubicin and UV radiation and the mutagenic response to daunorubicin.     

Lethal and sublethal effects of marine sediment extracts on fish cells and chromosomes

The cost of conducting conventional chronic bioassays with every potentially toxic compound found in marine ecosystems is prohibitive; therefore short-term toxicity tests which can be used for rapid screening were developed. The tests employ cultured fish cells to measure lethal, sublethal or genotoxic effects of pure compounds and complex mixtures. The sensitivity of these tests has been proven under laboratory conditions; the following study used two of these tests, the anaphase aberration test and a cytotoxicity assay, under field conditions. Sediment was collected from 97 stations within Puget Sound, Washington. Serial washings of the sediment in methanol and dichloromethane yielded an organic extract which was dried, dissolved in DMSO and incubated as a series of dilutions with rainbow trout gonad (RTG-2) cells. The toxic effects of the extract were measured by examining the rate of cell proliferation and the percentage of damaged anaphase figures. Anaphase figures were considered to be abnormal if they exhibited non-disjunctions, chromosome fragments, or chromosome bridges. A second cell line (bluegill fry, BF-2) was also tested for cell proliferation and was included because, unlike the RTG-2 cell line, it contains little or no mixed function oxygenase activity. Of 97 stations tested, 35 showed no genotoxic activity, 42 showed high genotoxic activity (P.01) and the remainder were intermediate. Among the toxic sites were several deep water stations adjacent to municipal sewage outfalls and four urban waterways contaminated by industrial and municipal effluents. Extracts from areas that showed genotoxic effects also inhibited cell proliferation and were cytotoxic to RTG-2 cells. Few effects were noted in the MFO deficient BF-2 cells. Short term in vitro tests provide aquatic toxicologists with a versatile and cost effective tool for screening complex environments. Through these tests one can identify compounds or geographic regions that exhibit high cytotoxic or genotoxic potential.     

In vitro genotoxic effects of the anticancer drug gemcitabine in human lymphocytes

This research was carried out to investigate in vitro genotoxic effects of the anticancer agent gemcitabine on the induction of chromosomal aberrations and sister-chromatid exchange in human lymphocytes. Three doses of gemcitabine (0.001, 0.002 and 0.004 microg/ml) were applied to lymphocyte cultures from 15 donors. There was a significant increase in the induction of chromosome aberrations and in the occurrence of sister-chromatid exchange in these cells. In addition, gemcitabine significantly decreased the mitotic index and replicative index for all doses. Dose-response regression lines were used to compare the individual susceptibilities to gemcitabine with respect to the chromosome aberration and sister-chromatid exchange frequencies. Our results indicate that gemcitabine is able to induce both cytotoxic and genotoxic effects in human lymphocyte cultures in vitro in a dose-dependent manner.     

Assessment of in vitro cytotoxic and genotoxic activities of some trimethoprim conjugates

Trimethoprim, a commonly used antibacterial agent, is widely applied in the treatment of variety of infections in human. A few studies have demonstrated an extensive exposure of man to antibiotics, but there is still a lack of data for cytotoxic effects including nephrotoxicity, gastrointestinal toxicity, hematotoxicity, neurotoxicity and ototoxicity. The main purpose behind this study was to determine cytotoxic and genotoxic activities of trimethoprim (1), trimethoprim with maleic acid (2) and trimethoprim in conjugation with oxalic acid dihydrate (3). The cytotoxic effects of these three conjugates were elucidated by employing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoium bromide (MTT) assay using embryonic rat fibroblast-like cell line (F2408) and H-ras oncogene activated embryonic rat fibroblast-like cancer cell line (5RP7). Additionally, determination of genotoxic activity of these three compounds were studied by using cytokinesis blocked micronucleus assay (CBMN) in human lymphocytes. The results demonstrated that trimethoprim alone and its combination with other compounds are able to induce both cytotoxic and genotoxic damage on cultured cells (F2408, 5RP7, human lymphocytes).     

A comparative study of genotoxic effects of anti-topoisomerase II drugs ICRF-193 and bufalin in Chinese hamster ovary cells

With the ultimate purpose of testing the existence of possible differences in the effectiveness of the topoisomerase II catalytic inhibitor ICRF-193 (a bisdioxopiperazine) and the enzyme suppressor bufalin (a bufadienolide from toad venom) we have carried out a series of experiments aimed at inducing cytotoxicity as well as DNA and chromosome damage in transformed CHO cells. In order to assess any possible influence of DNA repair capacity of the treated cells on the final outcome, we have made use of the repair-defective CHO mutant EM9, which shows a defect in DNA single- and double-strand breaks repair for comparison with its repair-proficient parental line AA8.Our results seem to indicate that, while both ICRF-193 and bufalin suppress cell growth and result in a clear inhibition of topoisomerase II catalytic activity, only ICRF-193 has been shown as able to induce both chromosome and DNA damage, with a more pronounced effect in the CHO mutant EM9 than in the repair-proficient line AA8.     

Prostaglandins can modify gamma-radiation and chemical induced cytotoxicity and genetic damage in vitro and in vivo

The effect of prostaglandin E1, E2, and F2 alpha on gamma-radiation, benzo(a)pyrene and diphenylhydantoin-induced cytotoxicity in vivo and genotoxicity in vitro was investigated. Prostaglandin E1 prevented both cytotoxic and genotoxic actions of all the three agents, where as both PGE2 and PGF2 alpha were ineffective. In fact, it was seen that both PGE2 and PGF2 alpha are genotoxic by themselves. Gamma-linolenic acid and dihomogamma-linolenic acid, the precursor of PGE1 were also as protective as that of PGE1, where as arachidonic acid, the precursor of 2 series PGs, has genotoxic actions to human lymphocytes in vitro. These results suggest that prostaglandins and their precursors can determine the susceptibility of cells to cytotoxic and genotoxic actions of chemicals and radiation. This study is particularly interesting since, it is known that some tumor cells contain excess of PGE2 and PGF2 alpha and many carcinogens can augment the synthesis of 2 series of PGs.     

A Topoisomerase II-Dependent Checkpoint in G2-Phase Plant Cells Can Be Bypassed by Ectopic Expression of Mitotic Cyclin B2

DNA topoisomerase II is required for mitotic chromosome condensation and segregation. Here we characterize the effects of inhibiting DNA topoisomerase II activity in plant cells using the non-DNA damaging topoisomerase II inhibitor ICRF-193. We report that ICRF-193 abrogated chromosome condensation in cultured alfalfa (Medicago sativa L.) and tobacco (Nicotiana tabaccum L.) mitoses and led to bridged chromosomes at anaphase. Moreover, ICRF-193 treatment delayed entry into mitosis, increasing the frequency of cells having a pre-prophase band of microtubules, a marker of late G2 and prophase, and delaying the activation of cyclin-dependent kinase. These data suggest the existence of a late G2 checkpoint in plant cells that is activated in the absence of topoisomerase II activity. To determine whether the checkpoint-induced delay was a result of reduced cyclin-dependent kinase activity, mitotic cyclin B2 was ectopically expressed. Cyclin B2 bypassed the ICRF-193-induced delay before mitosis, and correspondingly, reduced the frequency of interphase cells with a pre-prophase band. These data provide evidence that plant cells possess a topoisomerase II-dependent G2 cell cycle checkpoint that transiently inhibits mitotic CDK activation and entry into mitosis, and that is overridden by raising the level of CDK activity through the ectopic expression of a plant mitotic cyclin.

Key Words:

Plant cyclin B2, Topoisomerase II, ICRF-193, G2 checkpoint, Microtubules     

The genotoxic and anti-genotoxic effects of <Emphasis Type="Italic">Stachys petrokosmos</Emphasis> leaf extract in human lymphocytes using microsomal fractions

The genotoxic and anti-genotoxic effects of Stachys petrokosmos leaf extracts (Sp) were investigated in human lymphocytes. The cells were treated with 1.5, 3.0 and 6.0 μL/mL concentrations of Sp leaf extracts for 24 and 48 h treatment periods in the absence and presence of metabolic activator (S9mix). In the absence of S9mix, Sp alone did not induce chromosome aberrations and formation of micronucleus while inducing the mean sister chromatid exchange at the highest concentration. In addition, Sp decreased the mutagenic effect of mitomycin-c. Sp alone showed a cytotoxic effect determined by a decrease in the proliferation index, mitotic index and nuclear division index. On the other hand a mixture of Sp and mitomycin-c resulted in a higher cytotoxic effect especially for 48 h treatment period. In the presence of S9mix, Sp was not genotoxic and cytotoxic however, it showed an anti-genotoxic effect by decreasing the effects of cyclophosphamide.     

The comet assay differentiates efficiently and rapidly between genotoxins and cytotoxins in quiescent cells

Our main aim was to establish the efficiency of the single cell electrophoresis technique for differentiating between drugs that bind DNA and those that do not. The alkaline comet assay was used to test the responses of human leukocytes (quiescent cells) to damage induced by reportedly genotoxic and reportedly cytotoxic agents. Incubation of G0 leukocytes for 1 h with the genotoxic agents camptothecin and actinomycin C provoked DNA migration, observed as comet figures. On the other hand, when cells were treated with the cytotoxic agents cordycepin, fluorodeoxyuridine and puromycin, the leukocyte nuclei were indistinguishable from those of untreated cells. In addition, we have developed a rapid method using non-proliferating cells that requires neither culture nor lymphocyte isolation. This method promises to be useful as a rapid in vitro screening assay.     

Spatial Positioning of All 24 Chromosomes in the Lymphocytes of Six Subjects: Evidence of Reproducible Positioning and Spatial Repositioning following DNA Damage with Hydrogen Peroxide and Ultraviolet B

The higher-order organization of chromatin is well-established, with chromosomes occupying distinct positions within the interphase nucleus. Chromatin is susceptible to, and constantly assaulted by both endogenous and exogenous threats. However, the effects of DNA damage on the spatial topology of chromosomes are hitherto, poorly understood. This study investigates the organization of all 24 human chromosomes in lymphocytes from six individuals prior to- and following in-vitro exposure to genotoxic agents: hydrogen peroxide and ultraviolet B. This study is the first to report reproducible distinct hierarchical radial organization of chromosomes with little inter-individual differences between subjects. Perturbed nuclear organization was observed following genotoxic exposure for both agents; however a greater effect was observed for hydrogen peroxide including: 1) More peripheral radial organization; 2) Alterations in the global distribution of chromosomes; and 3) More events of chromosome repositioning (18 events involving 10 chromosomes vs. 11 events involving 9 chromosomes for hydrogen peroxide and ultraviolet B respectively). Evidence is provided of chromosome repositioning and altered nuclear organization following in-vitro exposure to genotoxic agents, with notable differences observed between the two investigated agents. Repositioning of chromosomes following genotoxicity involved recurrent chromosomes and is most likely part of the genomes inherent response to DNA damage. The variances in nuclear organization observed between the two agents likely reflects differences in mobility and/or decondensation of chromatin as a result of differences in the type of DNA damage induced, chromatin regions targeted, and DNA repair mechanisms.     

Cytotoxic and cytogenetic effects of α-copaene on rat neuron and N2a neuroblastoma cell lines

Alpha-copaene (α-COP), a tricyclic sesquiterpene, is present in several essential oils of medicinal and aromatic plants and has antioxidant and antigenotoxic features. Its cytotoxic, cytogenetic and oxidative effects have not been investigated in neuron and N2a neuroblastoma (NB) cell cultures. Therefore, we aimed to describe in vitro: (i) cytotoxic properties by 3-(4,5-dimetylthiazol-2-yl)-2,5-diphenlytetrazolium bromide test; (ii) antioxidant/oxidant activity by total antioxidant capacity (TAC) and total oxidative status (TOS) analysis; and (iii) genotoxic damage potential by single cell gel electrophoresis — of α-COP in healthy neuron and N2a-NB cell cultures for the first time. Significant (P < 0.05) decrease in cell proliferation were observed in cultured primary rat neurons starting with the concentration of 150 mg/L and in N2a-NB cells starting with 100 mg/L. In addition, 25 mg/L of α-COP treatment caused increase of TAC levels and α-COP treatments at higher doses led to increase of TOS levels in neuron N2a-NB cell cultures. Moreover, none of the tested concentrations of α-COP have shown a genotoxic effect on both cell lines. Our findings clearly demonstrate that α-COP exhibited mild cytotoxic effects on N2a-NB cell line. In conclusion, α-COP may have potential as an anticancer agent, which needs to be further studied.     

Specific Uptake and Genotoxicity Induced by Polystyrene Nanobeads with Distinct Surface Chemistry on Human Lung Epithelial Cells and Macrophages

Nanoparticle surface chemistry is known to play a crucial role in interactions with cells and their related cytotoxic effects. As inhalation is a major route of exposure to nanoparticles, we studied specific uptake and damages of well-characterized fluorescent 50 nm polystyrene (PS) nanobeads harboring different functionalized surfaces (non-functionalized, carboxylated and aminated) on pulmonary epithelial cells and macrophages (Calu-3 and THP-1 cell lines respectively). Cytotoxicity of in mass dye-labeled functionalized PS nanobeads was assessed by xCELLigence system and alamarBlue viability assay. Nanobeads-cells interactions were studied by video-microscopy, flow cytometry and also confocal microscopy. Finally ROS generation was assessed by glutathione depletion dosages and genotoxicity was assessed by γ-H2Ax foci detection, which is considered as the most sensitive technique for studying DNA double strand breaks. The uptake kinetic was different for each cell line. All nanobeads were partly adsorbed and internalized, then released by Calu-3 cells, while THP-1 macrophages quickly incorporated all nanobeads which were located in the cytoplasm rather than in the nuclei. In parallel, the genotoxicity study reported that only aminated nanobeads significantly increased DNA damages in association with a strong depletion of reduced glutathione in both cell lines. We showed that for similar nanoparticle concentrations and sizes, aminated polystyrene nanobeads were more cytotoxic and genotoxic than unmodified and carboxylated ones on both cell lines. Interestingly, aminated polystyrene nanobeads induced similar cytotoxic and genotoxic effects on Calu-3 epithelial cells and THP-1 macrophages, for all levels of intracellular nanoparticles tested. Our results strongly support the primordial role of nanoparticles surface chemistry on cellular uptake and related biological effects. Moreover our data clearly show that nanoparticle internalization and observed adverse effects are not necessarily associated.     

Hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale (Eubalaena glacialis) lung and testes fibroblasts

Although hexavalent chromium is a known genotoxic agent in human and terrestrial mammals and is present in seawater and air, its effects on marine mammals including the endangered North Atlantic right whale are unknown and untested. The present study investigated the cytotoxic and genotoxic effects of hexavalent chromium in primary cultured North Atlantic right whale lung and testes fibroblasts and levels of total chromium in skin biopsies from North Atlantic right whales. Cytotoxicity was measured by clonogenic survival assay. Genotoxicity was measured as production of chromosome aberrations. Tissue chromium levels were determined from skin biopsies of healthy free-ranging whales in the Bay of Fundy using inductively coupled plasma optical emission spectroscopy. Hexavalent chromium-induced concentration-dependent increases in right whale lung and testes fibroblast cytotoxicity with the testes more sensitive to the cytotoxic effects. It also induced concentration-dependent increases in chromosomal aberrations in both cell types with no significant difference in sensitivity. Skin biopsy data indicate that North Atlantic right whales are exposed to chromium and accumulate a range of 4.9-10 microg Cr/g tissue with a mean of 7.1 microg/g. Hexavalent chromium is cytotoxic and genotoxic to North Atlantic right whale cells. The whales have tissue chromium levels that are concerning. These data support a hypothesis that chromium may be a concern for the health of the North Atlantic right whales. Considering these data with chromium chemistry, whale physiology and atmospheric chromium levels further suggest that inhalation may be an important exposure route.