氧化石墨烯遗传毒性的实验研究

研究氧化石墨烯(GO)的遗传毒性,考察其致突变作用,为GO在生物领域的安全应用提供依据。采用Ames试验、体外CHL细胞染色体畸变试验和小鼠体内染色体畸变试验,分别在细菌水平、细胞水平及整体动物水平研究GO的遗传毒性。GO各剂量组的Ames试验结果为阴性。CHL试验中,CHL细胞染色体畸变率随GO浓度的增加而升高,其中1.000 mg·mL~(-1)剂量组(+S_9)和0.500 mg·mL~(-1)剂量组(-S_9)畸变率显著升高(P 0.05)。小鼠骨髓细胞染色体畸变试验中,骨髓细胞染色体畸变率同样随GO浓度的增加而升高,1.000和0.500 mg·kg~(-1)剂量组的畸变率显著提高(P 0.05)。虽然Ames试验结果没有反映出GO的遗传毒性,但在体外及体内染色体畸变试验中,GO均表现出对哺乳动物细胞染色体有潜在的遗传毒性。     

Mutagenicity of polyaromatic hydrocarbons by chemical models for cytochrome P450 in Ames assay

DNA damage is an important step in carcinogenesis. The Ames assay is a short-term screening of carcinogens that induce DNA damage. Most carcinogens require enzymatic activation through oxidation by cytochrome P450 (CYP450) in the presence of S9 mix. A combination of iron (Fe)(III) porphyrin and an oxidant is also able to oxidize compounds as an alternative metabolic pathway to CYP450. Previously it was reported that a chemical model containing a water-soluble 5,10,15,20-tetrakis(1-methylpyridinium4-yl)porphyrinatoiron(III) chloride (4-MPy) and tert-butyl hydroperoxide (t-BuOOH) activated aromatic amines and amides. In this study, a chemical model composed of an Fe porphyrin, water-insoluble 5,10,15,20-tetrakis(pentafluorophenyl)porphyrinatoiron(III) chloride (F₅P) or water-soluble 4-MPy was optimized with an oxidant – t-BuOOH, magnesium monoperoxyphthalate (MPPT), or iodosylbenzene (PhIO). Subsequently the mutagenicity of benzo[a]pyrene (B[a]P) and chrysene in Salmonella typhimurium TA strains was compared. B[a]P was activated by a combination of F₅P or 4-MPy plus MPPT or PhIO in S. typhimurium TA1538. The B[a]P-induced mutagenicity with F₅P plus oxidant was higher than 4-MPy plus oxidant. Mutagenicity of chrysene, a tetracyclic aromatic hydrocarbon, was not detected in the presence of F₅P/PhIO in S. typhimurium TA98, but was activated in the presence of F₅P/MPPT. The F₅P/MPPT activated other polyaromatic hydrocarbons (PAH) in the S. typhimurium TA98 assay including dibenz[a,c]anthracene, dibenz[a,h]anthracene, 3-methylcholanthrene, and benzo[a]anthracene. The results indicated that the F₅P/MPPT was the most efficient model for detecting PAH-induced mutagenicity in the Ames assay.     

Induction of gene mutations in salmonella and Drosophila by soluble Cr(Vi) compounds: Synergistic effects of nitrilotriacetic acid

The interaction between NTA and soluble Cr(VI) (K₂Cr₂O₇) was studied by the Ames test on S. typhimurium and the sex‐linked recessive lethal test on D. melanogaster. In both systems a synergistic effect of NTA on Cr(VI) mutagenicity took place at sub‐toxic doses of Cr(VI). The synergism could depend on the action of NTA on intracellular Cr(VI) reduction, as more Cr(VI) was reduced in vitro to Cr(III) by Salmonella and Drosophila protein extracts in the presence of NTA. A similar enhancement of soluble Cr(VI) mutagenicity was produced by low doses of EDTA.     

Gingko biloba extract and cobalt porphyrin additive to remove harmful components from cigarette smoke and reduce its toxicity

Cigarette filters were modified with a combination of gingko biloba extract and cobalt porphyrin (CGC) to remove harmful components from the cigarette smoke and reduce its toxicity. Smoke analysis results indicated that CGC eliminated up to 32% of benzo[a]pyrene (B[a]P), 52% of N-nitrosonornicotine (NNN), 46% of N-nitrosoanabasine (NAB), 35% of 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone (NNK), 31% of N-nitrosoanatabine (NAT), 30% of gas-phase free radicals, and 33% of solid-phase free radicals. Biological experiments, including the Ames test, neutral red cytotoxicity assay and chronic toxicity, were conducted for both CGC cigarettes and control cigarettes. Results showed that the toxicity of the CGC cigarettes was lower than those of the control cigarettes. The mechanism by which the CGC components could remove harmful components from cigarette smoke is discussed.     

Evaluation of the antimutagenic and antiradical potentials of extracts from the tubers of (Tunisian) Cyperus rotundus

The mutagenic potential of aqueous, total oligomers flavonoids (TOF), ethyl acetate and methanol extracts from tubers of Cyperus rotundus L. was assessed using Ames Salmonella tester strains TA98 and TA100, and SOS chromotest strain Escherichia coli PQ37 with and without metabolic activation (S9). None of the different extracts produced a mutagenic effect. Likewise, the antimutagenicity of the same extracts was tested using the “Ames test” and the “SOS chromotest”. Our results showed that C. rotundus extracts possess antimutagenic effects against S. typhimurium TA98 and TA100 strains towards the mutagen aflatoxin B1 (AFB1), similar to E. coli PQ37 strain against AFB1 and Nifuroxazide mutagens using the SOS chromotest assay. A free radical scavenging test was used in order to explore the antioxidant capacity of the extracts obtained from the tubers of C. rotundus. TOF, ethyl acetate and methanol extracts showed an important free radical scavenging activity towards the 1,1-diphenyl-2-picrylhydrazine (DPPH) free radical. These extracts showed an IC50 value of respectively 5, 20 and 65?µg?mL^?1. The beneficial effects of TOF, ethyl acetate and methanol extracts of C. rotundus were assessed by antioxidant and antimutagenic activities.     

Induction of micronuclei in tadpoles of Odontophrynus americanus (Amphibia: Leptodactylidae) by the pyrethroid insecticide cypermethrin

Cypermethrin (CY) is an active cyano pyrethroid effective against a wide range of pests encountered in agriculture and forestry. Although CY is not mutagenic in in vitro assays for gene mutation, in vivo assays showed conflicting results. In vivo genotoxicity of the synthetic pyrethroid CY in erythrocytes of Odontophrynus americanus tadpoles was examined. The frequency of micronuclei (MN) was recorded in blood smears obtained from tadpoles exposed in vivo to four different nominal concentrations 5, 10, 20 or 40?µg?L^?1 of the compound and fixed at two sampling times 48 and 96?h. As a positive control larvae were exposed to 40?mg?L^?1 of cyclophosphamide (CP). Tadpoles exposed to all CY treatments showed a significant increase in single small MN compared to the negative control group after 48?h and at 5 and 10?µg?L^?1 of CY at 96?h. Results obtained here demonstrated the genotoxic effects of the commercial formulation CY in the anuran larvae analyzed. Thus, data suggest that measurements of MN and other erythrocytes morphological aberrations performed in circulating blood samples of O. americanus tadpoles is a method for detecting cytogenetic damage in other native species.     

Lack of genotoxic potential of permethrin in mice evaluated by the comet assay and micronucleus test

Permethrin is a common insecticide that does not show genotoxic potential in standard in vitro and in vivo assays. To investigate the genotoxic potential of permethrin in more detail, two in vivo studies were conducted on female mice to assess DNA damage in tumor target organs by the comet assay and micronucleus test. For this, mice were administered permethrin at doses of 150, 300, or 600 mg/kg/day by gavage for 2 days, and their lung, liver, glandular stomach, peripheral blood, and bone marrow cells were examined for DNA damage. There were no significant increases in % tail DNA in the organs examined and no increase in micronuclei in peripheral blood by flow cytometry. Taken together, the present findings provide evidence that permethrin has no genotoxic, aneugenic, or clastogenic potential.     

Multiple-time contamination of benzo(a)pyrene in soils inhibits soil enzymatic activities

Benzo[a]pyrene (B[a]P) is accumulating in soils in a low-dose cumulative manner. The objectives of this study were to investigate the effects of B[a]P on the extractable and available fractions of B[a]P and on soil enzymatic activity using multiple-time superimposed and one-time contamination approaches. Results showed that the contents of B[a]P rapidly decreased in the first 14?d and later decreased slowly from 14 to 56?d in both one-time and multiple-time contamination tests. The contents of B[a]P in the multiple-time contamination test were lower than those in the one-time test. Soil urease, sucrase and dehydrogenase activities were rapidly inhibited in the early stage (14?d) and stimulated during the rest of the incubation, and soil dehydrogenase activity was more sensitive to B[a]P contamination than the other enzymes. High concentrations of B[a]P in soil led to greater inhibition of enzymatic activity than that at low concentrations in the early period of culture. Soil enzyme activities were weakly inhibited in multiple-time compared with in one-time contamination tests and were lower in the subsurface layer than in the surface layer. Our results revealed that the multiple-time superimposed approach might be better than one-time contamination for evaluating B[a]P risk in soil.     

Assessment of the in vivo genotoxicity of a new formulation of Bacillus thuringiensis var israelensis SH-14

Biological control agents have become a useful alternative for the reduction of the use of chemical insecticides. LABIOFAM (Cuba) is developing a new formulation of a biolarvicide that possesses as active biological agent Bacillus thuringiensis var israelensis serotype H14. In order to evaluate the genotoxicity of this new formulation, an in vivo battery test was used: micronucleus (MN), chromosome aberrations (CAs), and sperm morphology (SM) assays. A dose of 6.45?×?10⁸ spores was administered per animal via oral administration. Bone marrow cells were collected 24?h after a two day treatment for the MN assay, and 24?h after a unique treatment for the CA assay, using cyclophosphamide as the positive control. Sperm cells were collected at 5 weeks from the first of five administrations for the SM test, using acrylamide as positive control. Bacillus thuringiensis var israelensis serotype H14 failed to show either a significative increase of micronucleated polychromatic erythrocytes, chromosomal aberrations, or sperm abnormalities. Acute oral administration of a high dose of Bacillus thuringiensis var israelensis serotype H14 did not produce mutagenic effects in bone marrow or sperm cells.     

Degradation of Benzo[a]Pyrene in Soil with Arbuscular Mycorrhizal Alfalfa

Mycorrhizal and non-mycorrhizal alfalfa (Medicago sativa) was grown in pots containing soil artificially contaminated with various levels of benzo[a]pyrene (B[a]P)(0, 1, 10 and 100 mg kg^–1). Soil and plants were sampled after 30, 40, 50, 60 and 90 days and compared with unlanted pots. The percentage of mycorrhizal root length colonized by Glomus caledoniun was not significantly affected by the addition of B[a]P up to 10 mg kg^–1 but was significantly lower at 100 mg kg^–1B[a]P compared with low concentrations (p < 0.05). There was no difference in soil polyphenol oxidase and dehydrogenase activity among the controls and applications of 1 and 10 mg kg^–1 of B[a]P. However, enzyme activities were significantly higher at 100 mg kg^–1B[a]P compared with the other three treatments, and there was no mycorrhizal effect. Over a period of 90 days the concentration of B[a]P in soil in which alfalfa was grown was significantly lower than in unplanted soil (p < 0.05). Degradation rates of B[a]P added at 1, 10 and 100 mg kg^–1 without G. caledonium were 76, 78 and 53%, and with mycorrhizal inoculation were 86, 87 and 57%. The degradation rate in unplanted soil was significantly lower than in planted soil, and was significantly higher in medium- and low-B[a]P treatments than in the high B[a]P concentration tested. There is a possibility of enhancement phytoremediation of PAHs in rhizosphere soil with arbuscular mycorrhizal fungi.     

In situ evaluation of the genotoxic potential of the river Nile: I. Micronucleus and nuclear lesion tests of erythrocytes of Oreochromis niloticus niloticus (Linnaeus, 1758) and Clarias gariepinus (Burchell, 1822)

This study aimed to investigate the genotoxic potential of chemicals present along the course of the river Nile using frequencies of micronuclei (MN) and nuclear lesions (NL) in erythrocytes of Nile tilapia Oreochromis niloticus niloticus and African catfish Clarias gariepinus, as biomarkers. Results showed that most of the physicochemical parameters detected and heavy metal concentrations were significantly higher in the water collected from the estuaries of the river Nile compared to other sites of the upper Nile. The frequencies of MN and NL in peripheral blood erythrocytes of Nile tilapia and African catfish were significantly higher in estuary sites in Damietta and Rosetta compared to upper sites. The lowest level of genotoxicity was observed at two sites (Aswan and Kena), considered to be less contaminated. Our results suggested that higher frequencies of MN and NL determined at Damietta and Rosetta sites may be indicative of damage produced by pollutants in these areas. The most remarkable result was that MN and NL frequencies appear to be strongly related to water quality at different sites examined, indicating that MN frequencies may serve as a reliable biomarker for testing genotoxicity in situ. The positive correlation between MN and NL induction suggested that NL may be a useful complementary assay for genotoxicity analyses when fish are used as experimental animals. It was also found that seasonal variations in MN and NL frequencies might contribute to a better understanding of genotoxic responses in the field. The use of fish as indicator organisms for monitoring the presence of genotoxic-inducing contaminants in the environment seemed justified because the effects of exposure to a “complex mixture” such as river water were obtained. Nile tilapia appears to be a more suitable bioindicator species than African catfish in studying genotoxic chemical pollution in the river Nile attributed to a higher sensitivity.     

离体模型预测鱼体肝脏清除速率：鲑鱼肝细胞和肝脏S9组分的比较

将离体肝细胞和肝脏S9组分用于获取鱼类的体外生物转化数据可以优化模拟评估对化学物质的生物富集作用。然而涉及2种方式之间的直接对比的研究却几乎没有。本研究采用冷藏保存的鲑鱼肝细胞来测定对于6种多环芳烃(PAHs)的体外本征清除速率。我们运用测定结果推测体内本征清除速率，并将其作为输入值输入一种充分搅匀的肝脏模型中来预测肝清除速率。将事先由体外灌流肝脏测定的速率作为参考来评价预测结果。在2种竞争结合的假说前提下，由鲑鱼肝细胞测出的肝清除速率与实现的测定结果基本一致(6种多环芳烃中的5种都保持在2.1倍差异以下)。尽管多环芳烃的高代谢率是可能的原因之一，这些发现与之前由肝脏S9组分得出的结果相似。对苯并芘这一种化合物而言，由S9数据得出的体内本征清除速率是由肝细胞得出结果的10倍左右，这一结果可能是由细胞吸收速率造成的传播限制引起的。尽管苯并芘的结果差异较大，由任何一种体外测试方法得出的体内本征清除速率结果通常是一致的。这些结果显示离体肝细胞和肝脏S9组分2种系统均可用于优化鱼类的生物富集评估，尤其对于体外反应速率较高的情况。不同系统在化工领域的应用性是否相同则需要进一步的研究工作。
精选自Kellie A. Fay, Patrick N. Fitzsimmons, Alex D. Hoffman， John W. Nichols. Comparison of trout hepatocytes and liver S9 fractions as in vitro models for predicting hepatic clearance in fish. Environmental Toxicology and Chemistry: Volume 36, Issue 2, pages 463–471, July 2017. DOI: 10.1002/etc.3572
详情请见http://onlinelibrary.wiley.com/wol1/doi/10.1002/etc.3572/full
     

Light absorption by a marine diatom: experimental observations and theoretical calculations of the package effect in a small Thalassiosira species

The relationship between in vivo light absorption efficiency of whole cells and in vitro absorption efficiency of algal pigments has been examined experimentally in the marine diatom Thalassiosira sp. In vitro absorption spectra were obtained for cells disrupted by either ultrasonic treatment or high-pressure shearing stress in a low-temperature (-40°C) pressure cell. A dimensionless measure of the magnitude of the package effect (Q _a ^*), calculated from the ratio of whole-cell to disrupted-cell absorption, ranged from about 0.5 at the blue absorption peak of chlorophyll a (λ=435 nm) to 0.7 at the red chlorophyll a peak (λ=670 nm) to 1.0 at the absorption minimum (λ=600 nm). Cell diameter was found to be an inappropriate measure of size for assessing the magnitude of the package effect. Instead, the effective optical diameter for calculation of intracellular self-shading was found to be less than the cell diameter. This observation is consistent with the fact that most algal pigments are contained within chloroplasts, and that chloroplast volume is necessarily smaller than cell volume.     

Antibacterial and antimutagenic activitiy of extracts and essential oil from (Tunisian) Pistacia lentiscus

Aqueous and flavonoid-enriched extract as well as essential oil (EO) obtained from leaves of Pistacia lentiscus were assessed for antibacterial and antimutagenic activities. Antibacterial activity of different extracts and EO were evaluated against six bacterial strains. A marked inhibitory effect was observed against Salmonella typhimurium, whereas lower activity was observed against Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enteritidis. EO showed significant inhibitory effects against Salmonella typhimurium, Salmonella enteritidis and Staphylococcus aureus. The antimutagenic activity of the different extracts against Aflatoxin B₁ (AFB₁) and sodium azide was demonstrated with the Salmonella typhymurium assay. The number of revertants per plate decreased significantly when the plant extracts were added to the assay system using Salmonella typhimurium TA100, TA98 and TA1535.     

Effect of latex material on antioxidant enzymes,lipid peroxidation,DNA damage,and chromosomal aberration

Cell integrity is affected by oxidative stress when the production of active oxidants overwhelms antioxidant defense mechanisms. Latex, a natural polymer obtained from Hevea brasiliensis, is used in medical industry for manufacturing surgical gloves, urinary catheters, and dental dams. The aim of this study was to evaluate the effects of latex material on oxidative stress by in vivo and in vitro methods. In addition, the material was screened for its ability to induce any chromosomal aberrations (CAs) by in vitro method. In vivo studies were carried out with implanted latex material onto subcutaneous tissue of various batches of experimental Wistar rats. At the end of experimental period, animals were anesthetized, blood was collected for serum analysis, and sacrificed. Liver was excised for the determination of antioxidant enzymes and lipid peroxidation (LPO). Subcutaneous tissues were obtained for the extraction of genomic DNA from implanted animals and checked for the presence of 8-hydroxy-2-deoxyguanosine (8-OHdG), considered an indicator of DNA damage. Simultaneously, in vitro studies were carried out using fresh liver and subcutaneous tissue obtained from Swiss albino mice treated with physiological saline extract of latex material. For the estimation of both in vitro and in vivo oxidative stress, 10% liver homogenate was assessed for stress indicators like reduced glutathione, glutathione reductase, glutathione peroxidase, LPO and protein content. The results of both in vivo and in vitro studies indicated that the chemical leachents from the latex material did not significantly affect LPO and the levels of antioxidant enzymes. There was also no significant increase in 8-OHdG content due to the presence of implanted latex material. Finally, the results of in vitro CA test and G banding indicated that extracts of test material did not induce any chromosomal abnormalities.     

SETAC GLB — Gründung und Entwicklung

Goal, Scope, and Background

In the context of the ISO-standardisation of the in vitro micronucleus test for (waste) water testing (ISO/DIS 21427-2), a national collaborative study was organized by the German Federal Institute of Hydrology (BfG) involving ten laboratories of private companies, universities and public authorities. The formation of micronuclei (MN) is a special kind of chromosomal aberration. To meet the standardisation requirements for this method, encoded waste water samples, some of them spiked with known genotoxins, had to be tested in a collaborative study. The study should demonstrate practicability of the in vitro micronucleus test for waste water testing and should provide validity data.

Material and Methods

The micronucleus assay was performed with the permanently growing Chinese hamster lung fibroblast cell line V79. Four encoded samples from one municipal and one industrial wastewater treatment plant were tested with and without metabolic activation by S9-mix. Two of these samples were spiked in advance with defined concentrations of the clastogenic substances cyclophosphamide and mytomycin C. The defined assessment criterion for genotoxicity was the lowest dilution of a sample that does not show any significant induction of micronuclei (LID; lowest ineffective dilution). Cytotoxicity was judged by determining the survival-index, i.e. the percentage growth rate of the cells compared with the respective negative controls. As supplementary qualitative criteria, the mitotic index and the proliferation index were assessed.

Results

Although some of the laboratories had little or even no experience with the protocol of the in vitro micronucleus test described in the ISO-draft, all participants suceeded in establishing the assay within few weeks and in generating viable test results. The two nongenotoxic samples were detected as negative by 90% or 100% of the participants. The mitomycin C-spiked sample (expected to be positive without S9 supplementation) was correctly evaluated as positive by all laboratories. The cyclophosphamide-spiked sample (expected to be positive with S9 supplementation) was evaluated correctly as genotoxic by 80% of the laboratories. A post-test analysis found evidence that the false-negative results were due to technical failure, but not of a methodological nature. The sample LID values varied by no more than one dilution step around the median LID-value for all samples investigated. The survival index was proven to be a robust measure for estimation of cytotoxicity.

Discussion

The measurement of micronuclei is an important parameter for the detection of cytogenetic damage. In contrast to the single-cell gel electrophoresis assay (Comet assay), which is used as an indicator test, the in vitro micronucleus test detects non-repairable and thus manifested genetic damage. Consequently, the in vitro micronucleus test can be regarded as the more significant test system. A more frequent occurrence of micronuclei in treated cells suggests a risk of severe genetic damage for subsequent cell generations. In the interest of a precautionary environmental protection and health protection no municipal or industrial waste-water samples should show any significant induction of micronuclei in the treated cell populations.

Perspectives

The presented collaborative study was the first interlaboratory comparison of the in vitro micronucleus test using wastewater samples. The test system is intended to complement the already DIN- and ISO-standardised bacterial tests, i.e. the umu-test and the Ames plate incorporation assay. The data generated in the course of this project justify the transformation of the draft standard into the final draft international standard (FDIS), the preliminary stage of an international norm, so that a valid, standardised test system for the detection of cukaryotic genotoxicity in water samples might become available.     

Genotoxicity study of phenol and o-cresol using the micronucleus test and the comet assay

Phenol and cresols are common toxic environmental pollutants. In this study, the micronucleus assay and the alkaline single cell gel electrophoresis (SCGE) technique have been used to investigate the genotoxic activity of phenol and o-cresol. The result of experiments revealed that phenol and o-cresol were both evident genotoxins, and the genotoxic activity of o-cresol was stronger. In the micronucleus assay, phenol and o-cresol could both cause a significant increase in the micronucleus (MN) frequencies (p?p?p?p?相似文献   

Toxicological and ecological implications of biotransformation enzymes in the tropical teleost Chaetodon capistratus

Hepatic cytochromes P450 (phase I monooxygenases) and glutathione transferases (phase II conjugating enzymes) were investigated in Chaetodon capistratus (Linnaeus) collected in Florida and Belize in June and December 1991, respectively. These biotransformation enzymes play major roles in the detoxification of xenobiotics by converting lipophilic chemicals to more hydrophilic, readily excretable metabolites. Content of total microsomal P450 (0.501 to 0.821 nmol mg^-1 microsomal protein) and rates of NADPH-cytochrome c (P450) reductase (270.7 to 330.2 nmol min^-1 mg^-1 microsomal protein) and glutathione transferase (2.81 to 3.12 g min^-1 mg^-1 cytosolic protein) in these fish were greater than in most untreated fish species, i.e., fish that have not been exposed to PAHs (polycyclic aromatic hydrocarbons) or PCBs (polycyclic biphenyls). Ethoxyresorufin O-deethylase (EROD) rates (0.029 to 0.171 nmol min^-1 mg^-1) were also comparable to those in most untreated marine fish. Immunoblot analysis with monoclonal antibody (MAb) 1-12-3 to scup P450E (the EROD catalyst and a teleost representative of the PAH-inducible CYP1A gene subfamily) showed slight amounts of cross-reacting protein in C. capistratus liver microsomes. Hepatic CYP1A content and EROD activity did not differ significantly between fish collected in Florida and Belize, suggesting that the two sites differed little in contamination by CYP1A inducers. Immunochemical analyses with polyclonal antibodies to scup P450B (a teleost representative of the CYP2B subfamily) and human CYP3A4 cross-reacted strongly with C. capistratus hepatic proteins. The CYP2B and CYP3A subfamilies in mammals are believed to have partially evolved in response to toxic dietary allelochemicals. C. capistratus regularly feeds on terpenoid-rich gorgonian corals, suggesting that biotransformation enzymes may be involved in the metabolism of dietary allelochemicals as well as anthropogenic xenobiotics in this species.     

Genotoxic assessment of anthracene and benzo [a] pyrene to milkfish Chanos chanos

Mutagenic and genotoxic effects of polycyclic aromatic hydrocarbons, anthracene and benzo [a] pyrene (BaP), in milkfish Chanos chanos were determined using micronucleus (MN) test and comet assay (CA). Distinct mean frequencies of nuclear abnormalities such as MNs; binucleated micronuclei, nuclear bud, and fragmented apoptotic cells were measured. Significant increase in DNA damage with five classes of damage level was observed and expressed in terms of arbitrary unit (AU). Mean frequencies of total nuclear abnormalities were 0.5?±?0.25 cells in control; 0.67?±?0.33 cells in solvent control; 70?±?9.60 cells in 0.176?mg?L^?1 anthracene, and 91.83?±?6.25 cells in 0.031?mg?L^?1 BaP. The greatest DNA damage of 170AU was observed in 0.176?mg?L^?1 anthracene-exposed group and 182AU was observed in 0.031?mg?L^?1 BaP-treated fish. This study confirmed that the CA and MN assays are useful tools in determining potential genotoxicity of water pollutants and might be appropriate as a part of monitoring program.     

Photoacclimation in phytoplankton: implications for biomass estimates, pigment functionality and chemotaxonomy

Chl a and C-normalized pigment ratios were studied in two dinophytes (Prorocentrum minimum and Karlodinium micrum), three haptophytes (Chrysochromulina leadbeateri, Prymnesium parvum cf. patelliferum, Phaeocystis globosa), two prasinophytes (Pseudoscourfieldia marina, Bathycoccus prasinos) and the raphidophyte Heterosigma akashiwo, in low (LL, 35 μmol photons m⁻² s⁻¹) and high light (HL, 500 μmol photons m⁻² s⁻¹). Pigment ratios in LL and HL were compared against a general rule of photoacclimation: LL versus HL ratios ≥1 are typical for light-harvesting pigments (LHP) and <1 for photoprotective carotenoids. Peridinin, prasinoxanthin, gyroxanthin-diester and 19′-butanoyloxy-fucoxanthin were stable chemotaxonomic markers with less than 25% variation between LL versus HL Chl a–normalized ratios. As expected, Chls exhibited LL/HL to Chl a ratios >1 with some exceptions such as Chl c ₃ in P. globosa and MV Chl c ₃ in C. leadbeateri. LL/HL to Chl a ratios of photosynthetic carotenoids were close to 1, except Hex-fuco in P. globosa (four-fold higher Chl a ratio in HL vs LL). Although pigment ratios in P. globosa clearly responded to the light conditions the diadinoxanthin-diatoxanthin cycle remained almost unaltered at HL. Total averaged pigment and LHP to C ratios were significantly higher in LL versus HL, reflecting the photoacclimation status of the studied species. By contrast, the same Chl a-normalized ratios were weakly affected by the light intensity due to co-variation with Chl a. Based on our data, we suggest that the interpretation of PPC and LHP are highly dependent on biomass normalization (Chl a vs. C).