Comparison of an assay for Dehalococcoides DNA and a microcosm study in predicting reductive dechlorination of chlorinated ethenes in the field

The study aims to compare the detection of 16S rRNA gene of Dehalococcoides species and the microcosm study for biotransformation in predicting reductive dechlorination of chlorinated ethenes in ground water at hazardous waste sites. A total of 72 ground water samples were collected from 12 PCE or TCE contaminated sites in the United States. The samples were analyzed and used to construct microcosms in the laboratory. The results showed that the presence of Dehalococcoides DNA was well associated with dechlorination to ethene in the field. Nearly half of the wells where Dehalococcoides DNA was detected had ethene as a dechlorination end product. In comparison, for ground water samples of 16 wells where ethene was detected, ethene was produced in 11 of the corresponding microcosms. For most microcosms, during two years of incubation, dechlorination was less extensive than that observed in the field.     

Assessing stress response of Stylophora pistillata towards oil and phosphate pollution in the Gulf of Aqaba,using molecular and biochemical markers

Crude oil (from oil terminal) and raw phosphate (from phosphate port) pollution are responsible for the lowered health conditions of coral reefs at their vicinity in the Jordanian coast of the Gulf of Aqaba. Both in situ incubations and ex situ laboratory exposure experiments were used to study the effects of those pollutants on corals, by using molecular and biochemical biomarkers in the coral Stylophora pistillata. For ex situ part of the experiment, crude oil and raw phosphate were added to a final concentration of 500?ppm for both pollutants. The DNA damage was assessed by Comet assay, while biochemical stress markers were reassessed by lipid peroxidation (LPO) test. Although the corals looked healthy from outside, the use of stress biomarkers indicated that they are under high pressure at the cellular level. The corals incubated with oil and phosphate had more DNA damage and LPO in comparison with the control samples. The results obtained suggest that the use of stress biomarkers can be used as important prognostic tools for examining the sub-lethal stress on corals before their death.     

重金属Cr(Ⅵ)、Pb及Cu胁迫对双齿围沙蚕体腔细胞的DNA损伤

为探讨重金属Cr(Ⅵ)、Pb以及Cu对沙蚕体腔细胞DNA的毒性效应,以双齿围沙蚕为受试动物,重金属按不同剂量水平,Cr(Ⅵ):10、100和200 mg· L-1,Pb:5、50和100 mg·L-1,Cu:1、10和20 mg· L-1,分别胁迫沙蚕24 h,以不加任何重金属离子的海水为对照,采用单细胞凝胶电泳技术,检测其体腔细胞DNA损伤程度.结果表明,与空白对照组相比,3种重金属离子的各浓度组都能引起沙蚕体腔细胞DNA损伤,且3种重金属胁迫浓度与细胞DNA损伤程度之间存在显著的剂量-效应关系.双齿围沙蚕可以作为单细胞凝胶电泳的实验材料用于重金属所致环境污染的生物监测指示生物.     

Urinary 8-oxo-7, 8-dihydro-2′-deoxyguanosine concentrations after frying of bacon,a pilot study

Cooking fumes contain compounds that may give rise to oxidative stress and mutations when inhaled. The aim of this study was to evaluate if cooking fumes from frying of bacon induce oxidative stress by measurement of urinary 8-oxo-7,8-dihydro-2 deoxyguanosine, a marker of oxidatively damaged DNA. Three non-smoking women fried bacon for 3 h. Urine samples were taken as early morning void at the same time on four days; the morning before frying, the morning after first frying, the morning after three days of frying and one week after first urine sample. 8-Oxo-7,8-dihydro-2 deoxyguanosine, 1-hydroxypyrene and 2-hydroxyphenanthrene, metabolites of polycyclic aromatic hydrocarbons, were measured by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). 8-Oxo-7,8-dihydro-2 deoxyguanosine correlated weakly with concentrations of 1-hydroxypyrene (r = 0.31, p = 0.042), but it did not correlate with 2-hydroxyphenanthrene (r = ?0.074; p = 0.64). Average urinary 8-oxo-7,8-dihydro-2 deoxyguanosine concentrations increased from the day before frying (16.3 ± 4.2 nmol/L) to the third day of frying (26.2 ± 10.2 nmol/L), although not statistically significantly. Our pilot study shows that frying of bacon may result in increased oxidative stress which further emphasises the possible carcinogenic potential of cooking fumes.     

重金属Cr(VI)、Pb及Cu胁迫对双齿围沙蚕体腔细胞的DNA损伤

为探讨重金属Cr(VI)、Pb以及Cu对沙蚕体腔细胞DNA的毒性效应,以双齿围沙蚕为受试动物,重金属按不同剂量水平,Cr(VI):10、100和200 mg·L~(-1),Pb:5、50和100 mg·L~(-1),Cu:1、10和20 mg·L~(-1),分别胁迫沙蚕24 h,以不加任何重金属离子的海水为对照,采用单细胞凝胶电泳技术,检测其体腔细胞DNA损伤程度。结果表明,与空白对照组相比,3种重金属离子的各浓度组都能引起沙蚕体腔细胞DNA损伤,且3种重金属胁迫浓度与细胞DNA损伤程度之间存在显著的剂量-效应关系。双齿围沙蚕可以作为单细胞凝胶电泳的实验材料用于重金属所致环境污染的生物监测指示生物。     

Effects of methamidophos on the community structure,antagonism towards Rhizoctonia solani,and phlD diversity of soil Pseudomonas

A microcosm incubation study using an aquic brown soil from northeast China (a Cambisol in the UN Food and Agriculture Organization FAO Soil Taxonomy) was conducted to examine the effects of different concentrations (0, 50, 150, and 250 mg kg^?1) of methamidophos (O,S-dimethyl phosphoramidothioato) on Pseudomonas, one of the most important gram-negative bacteria in soil. Amplified ribosomal DNA restriction analysis (ARDRA) was performed to study the Pseudomonas community structure, an in vitro assay was made to test the antagonistic activity of isolated Pseudomonas strains against soil-borne Rhizoctonia solani, a major member of the pathogens highly related to soil-borne plant diseases, and special primer amplification and sequencing were performed to investigate the diversity of phlD, an essential gene in the biosynthesis of 2, 4-diacetylphloroglucinol (2, 4-DAPG), which has biocontrol activity in phlD ⁺isolates. With exposure to increasing methamidophos concentrations, the total number of soil Pseudomonas ARDRA patterns decreased significantly, but with less change in the same treatments over 1, 3, and 5 weeks of incubation. The number of isolated Pseudomonas strains with antagonistic activity against R. solani as well as the diversity and appearance frequency of the strains' phlD gene also decreased with increasing concentrations of methamidophos, especially at high methamidophos concentrations. Applying methamidophos could increase the risk of soil-borne plant diseases by decreasing the diversity of the soil Pseudomonas community and the amount of R. solani antagonists, particularly those with the phlD gene.     

Evaluation of protective effects of sulforaphane on DNA damage caused by exposure to low levels of pesticide mixture using comet assay

The objective of the study was to evaluate the potential risk of DNA damage due to exposure to a mixture of the most widely used pesticides, namely endosulfan, chlorpyriphos and thiram at an environmentally relevant concentration (5 μM each) and the DNA protective capacity of sulforaphane (SFN) (10–30 μg/mL). DNA damage in human lymphocytes was ascertained with Single Cell Gel Electrophoresis (SCGE), also called Comet Assay. For positive control, H₂O₂ at 100 mM was used. The pesticide mixture produced DNA damage at the concentration used in the lymphocytes. SFN was able to offer a statistically significant (P < 0.01), concentration-dependant protection to DNA damage between 10–20 μg/mL in both the pre-incubation and co-incubation strategies. The results indicate that exposure to low levels of these pesticide mixtures can induce DNA damage, and the presence of SFN in diet may reduce the incidence of genetic damage, especially in farm workers. However, it is not clear whether SFN is involved in quenching of the free radicals generated by the pesticide mixture or it is involved in DNA repair mechanism.     

Mutagenicity evaluation of chemical pesticides

Abstract

Over the last few decades, the use of chemical pesticides has increased dramatically in the U.S. This relatively sudden increase greatly concerns the U.S. Environmental Protection Agency (EPA), since it has the responsibility for ensuring the safety of all pesticides used in the U.S. In response to this concern, EPA has established a review program, the Rebuttable Presumption Against Registration (RPAR), for periodically reassessing the mutagenic and carcinogenic potential of pesticide compounds.

This paper presents a review and evaluation of the data reported in the literature on six chemical pesticides suspect for mutagenic potential. The pesticide chemicals discussed are maleic hydrazide; rotenone; monuron; diallate; triallate, and benomyl.     

Parentage and sex allocation in the facultatively polygynous ant Myrmicatahoensis

Most social groups have the potential for reproductive conflict among group members. Within insect societies, reproduction can be divided among multiple fertile individuals, leading to potential conflicts between these individuals over the parentage of sexual offspring. Colonies of the facultatively polygynous ant Myrmicatahoensis contain from one to several mated queens. In this species, female sexuals were produced almost exclusively by one queen. The parentage of male sexuals was more complex. In accordance with predictions based on worker sex-allocation preferences, male-producing colonies tended to have low levels of genetic relatedness (i.e., high queen numbers). Correspondingly, males were often reared from the eggs of two or more queens in the nest. Further, over half of the males produced appeared to be the progeny of fertile workers, not of queens. Overall investment ratios were substantially more male biased than those predicted by genetic relatedness, suggesting hidden costs associated with the production of female sexuals. These costs are likely to include local resource competition among females, most notably when these individuals are adopted by their maternal nest. Received: 3 March 1998 / Accepted after revision: 20 June 1998