Polychlorinated biphenyl contamination and minisatellite DNA mutation rates of tree swallows

The evidence that exposure to polychlorinated biphenyls (PCBs) leads to mutations is equivocal and controversial. Using multilocus DNA fingerprinting, we compared the mutation rate of tree swallows (Tachycineta bicolor) nesting at sites with high and low levels of contamination with PCBs. The upper Hudson River, USA, is highly contaminated with PCBs as a result of releases from two capacitor manufacturing plants in Hudson Falls and Fort Edward, New York, USA. Tree swallows nesting nearby have some of the highest known concentrations of PCBs in their tissues of any contemporary bird population (up to 114,000 ng PCB/g tissue). We found no difference in mutation rates between sites in New York with high PCB contamination and reference sites in Wisconsin, USA, and Ontario and Alberta, Canada, with known or presumably low levels of contamination. Thus, the mechanism behind altered reproductive behavior of tree swallows along the upper Hudson River is most likely physiological impairment, such as endocrine disruption, rather than mutation.     

Acid precipitation and food quality: Inhibition of growth and survival in black ducks and mallards by dietary aluminum,calcium, and phosphorus

In areas impacted by acid precipitation, water chemistry of acidic ponds and streams often changes, resulting in increased mobilization of aluminum and decreased concentration of calcium carbonate. Aluminum binds with phosphorus and inhibits its uptake by organisms. Thus, invertebrate food organisms used by waterfowl may have inadequate Ca and P or elevated Al for normal growth and development. Acid rain and its effects may be one of the factors negatively impacting American black ducks (Anas rubripes) in eastern North America. One-day old mallards (A. platyrhynchos) and black ducks were placed on one of three Ca:P regimens: low:low (LL), normal:normal (NN), and low:high (LH) with each regimen divided further into three or four Al levels for 10 weeks. Forty-five % of the black ducks died on nine different diets whereas only 28% of the mallards died on three different diets. Mortality was significantly related to diet in both species. Growth rates for body weight, culmens, wings, and tarsi of both species on control diets exceeded those on many treatment diets but the differences were less apparent for mallards than for black ducks. Differences among treatments were due to both Ca:P and A1 levels.     

Flow cytometric DNA analysis of ducks accumulating 137Cs on a reactor reservoir

The objective of this study was to detect red blood cell (rbc) DNA abnormalities in male, game-farm mallard ducks as they ranged freely and accumulated 137Cs (radiocesium) from an abandoned nuclear reactor cooling reservoir. Prior to release, the ducks were tamed to enable recapture at will. Flow cytometric measurements conducted at intervals during the first year of exposure yielded cell cycle percentages of DNA (G0/G1, S, G2 + M phases) of rbc, as well as coefficients of variation (CV) in the G0/G1 phase. DNA histograms of exposed ducks were compared with two sets of controls which were maintained 30 and 150 miles from the study site. 137Cs live wholebody burdens were also measured in these animals in a parallel kinetics study, and an approximate steady-state equilibrium was attained after about 8 months. DNA histograms from 2 of the 14 contaminated ducks revealed DNA aneuploid-like patterns after 9 months exposure. These two ducks were removed from the experiment at this time, and when sampled again 1 month later, one continued to exhibit DNA aneuploidy. None of the control DNA histograms demonstrated DNA aneuploid-like patterns. There were no significant differences in cell cycle percentages at any time point between control and exposed animals. A significant increase in CV was observed at 9 months exposure, but after removal of the two ducks with DNA aneuploidy, no significant difference was detected in the group monitored after 12 months exposure. An increased variation in the DNA and DNA aneuploidy could, therefore, be detected in duck rbc using flow cytometric analysis, with the onset of these effects being related to the attainment of maximal levels of 137Cs body burdens in the exposed animals.     

Waterfowl and the bacteriological quality of amenity ponds

This study investigated the impact of waterfowl on the bacteriological quality of village ponds in East Yorkshire, north-east England. Water and sediment samples were collected from ponds with and without resident ducks and geese; faecal indicator and potentially pathogenic bacteria were assayed by membrane filtration and by selective enrichment. Escherichia coli, faecal streptococci and, to a degree, Clostridium perfringens were more abundant in ponds with waterfowl; Salmonella was isolated in June-August from the sediment of a pond with waterfowl. The results suggested that the bacteriological quality of village ponds might be adversely affected by waterfowl. All water samples from ponds with waterfowl had faecal indicators at higher concentrations than EU requirements for bathing waters. Although these ponds are not bathing waters we suggest skin contact and accidental ingestion of water should be avoided.     

Variation in mitochondrial DNA control region haplotypes in populations of the bank vole, Clethrionomys glareolus, living in the Chernobyl environment, Ukraine

Bank vole, Clethrionomys glareolus, specimens have been annually sampled from the radioactive Chernobyl, Ukraine, environment and nonradioactive reference sites since 1997. Exposed voles continually exhibit increased mitochondrial DNA haplotype (h) and nucleotide diversity (ND), observed in the hypervariable control region (1997-1999). Increased maternal mutation rates, source-sink relationships, or both are proposed as hypotheses for these differences. Samples from additional years (2000 and 2001) have been incorporated into this temporal study. To evaluate the hypothesis that an increased mutation rate is associated with increased h, DNA sequences were examined in a phylogenetic context for novel substitutions not observed in haplotypes from bank voles from outside Ukraine or in other species of Clethrionomys. Such novel substitutions might result from in situ mutation events and, if largely restricted to samples from radioactive environments, support an increased maternal mutation rate in these areas. The only unique substitution meeting this criterion was found in an uncontaminated reference site. All other substitutions are found in other haplotypes of the bank vole or in other species. Increased maternal mutation rates do not appear to explain trends in h and ND observed in northern Ukraine. Studies examining ecological dynamics will clarify the reasons behind, and significance of, increased levels of h in contaminated areas.     

Exposure assessment of residents living near a wood treatment plant

We report the results of environmental sampling and modeling in a neighborhood adjacent to a wood processing plant. This plant used creosote and pentachlorophenol (PCP) to treat wood for over 70 years. Between 1999 and 2001, environmental samples were obtained to quantify the level of environmental contamination from the wood processing plant. Blood from 10 residents was measured for chlorinated dioxins and dibenzofurans. Soil sediment samples from drainage ditches and attic/dust samples from nearby residents' homes were tested for polychlorinated dioxins, furans, and polycyclic aromatic hydrocarbons (PAH). The dioxin congeners analysis of the 10 residents revealed elevated valued for octachlorodibenzo-p-dioxin and heptachlorodibenzo-p-dioxin compatible with PCP as the source. The levels of carcinogenic PAHs were higher than background levels and were similar to soil contamination on wood preserving sites. Wipe sampling in the kitchens of 11 homes revealed that 20 of the 33 samples were positive for octachlorinated dioxins with a mean value of 10.27 ng/m2. The soil, ditch samples, and positive wipe samples from the homes indicate a possible ongoing route of exposure to the contaminants in the homes of these residents. Modeled air exposure estimated for the wood processing waste chemicals indicate some air exposure to combustion products. The estimated air levels for benzo(a)pyrene and tetrachlorodibenzodiozin in this neighborhood exceeded the recommended levels for these compounds in some states. The quantitative data presented suggest a significant contamination of a neighborhood by wood processing waste chemicals. These findings suggest the need for more stringent regulations on waste discharges from wood treatment plants.     

Investigation of a wood treatment facility: Impact on an aquatic ecosystem in the San Joaquin River, Stockton, California

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and metals were monitored in the river sediments near the McCormick and Baxter (MCB) wood treatment facility, Stockton, CA. Transplanted clams and resident fish species were used to assess bioavailability. The highest PCDD and PCDF contamination in sediments were confined to an area next to the facility and an area in the nearby Stockton harbor (DK location). Pentachlorophenol (PCP) wood treatment at MCB was the most probable source of the contamination. PCBs contaminated a wider area of the Stockton Ship Channel and harbor. Metal concentrations were uniformly low except for the metalloid arsenic in the Old Mormon Slough and lead and zinc near boat docks in the Stockton harbor. Despite high mortality rates, clams (Corbicula fluminea) bioaccumulated PCBs, PCDDs, and PCDFs. In clams, PCBs and 2,3,7,8 TCDD were much closer to equilibrium with the sediments than were higher chlorinated PCDDs and PCDFs. All fish were at background levels for 2,3,7,8 TCDD. All fish had lower lipid adjusted PCDD/F and PCB concentrations in the skinned muscle than in the whole fish. PCBs in fish were above background levels for United States river systems. Although high contamination exists in the river near this superfund site, adverse effects on the aquatic community could not be demonstrated.     

Effects of agricultural pond eutrophication on survival and health status of Scinax nasicus tadpoles

To test the hypothesis that eutrophication ponds modulate some aspects of the health responses and survival of anuran tadpoles, we conducted field experiments using Scinax nasicus as sentinel organism to evaluate the quality of two ponds filled with agricultural runoff in a dominant agricultural landscape of Mid-Western Entre Ríos Province (Argentina). The survival, growth and development rates, erythrocytes nuclei aberrations, parasite infection, and brain cholinesterase activity were monitored after seven days of exposure. Water samples from the ponds were also analyzed for physico-chemical variables and levels of pesticide residues. Residues of organochlorine pesticides and nutrients were higher in the agricultural ponds with respect to those from the control pond. We suggest that the interactions among washed-off nutrients and pesticides from agriculture and environmental factors account for deleterious effects on S. nasicus survival, growth and development rate, thereby compromising their health status. These effects can lead, in turn, to an increase in tadpole vulnerability to opportunistic parasites, erythrocytes nuclei aberrations or hemolysis.     

Effects of low pH,metals, and water hardness on larval amphibians

The interactions between pH, metals, and water hardness in determining the suitability of vernal ponds for amphibian reproduction were investigated through a fully factorial laboratory microcosm experiment. Naturally-occurring metals (Al, Cu, Fe, Pb, Zn) at concentrations analogous to those observed in prior field studies had variable effects on acute (7 day) and chronic (28 day) exposure survival for both the Jefferson salamander, Ambystoma jeffersonianum, and the wood frog, Rana sylvatica. Acute exposure to Al and Cu significantly reduced wood frog survival; increased water hardness significantly increased acute exposure wood frog survival. Acute exposure mortality of the Jefferson salamander was significantly higher in the Al and Cu treatments; in toxic metal treatments (Al and Cu), survival was higher at the low pH level. Chronic exposure of wood frogs to Al and Cu, higher pH level, and lower hardness levels greatly reduced survival. Chronic exposure of Jefferson salamander larvae to Al and Cu significantly reduced survival. Chronic Jefferson salamander survival was significantly greater in the higher pH treatments in the presence of non-toxic metals, however, survival was significantly decreased in the higher pH treatments in the presence of Al and Cu. There were no statistically significant effects of metals, pH, or hardness on wet mass of the pre-metamorphic larvae.The four conditions tested (pH, hardness, presence of metals, and amphibian species) are important determinants of toxicity observed in temporary pond amphibian breeding sites. Clearly, there is no single water chemistry parameter that can explain the toxicity of temporary ponds to the embryos and larvae of terrestrial amphibians that use the ponds for breeding.     

2007年海淀区部分酒店集中空调通风系统微生物检测分析

目的了解北京市海淀区酒店集中空调通风系统送风微生物污染状况。方法于2007年4月～10月监测了海淀区14家酒店的集中空调通风系统,分别对空调送风中空气细菌总数,真菌总数和β-溶血性链球菌、冷却水中嗜肺军团菌、风管内表面细菌总数和真菌总数进行检测。结果送风中空气细菌总数、真菌总数、β-溶血性链球菌合格率分别为60.0%、92.0%、100%;风管内表面细菌总数、真菌总数合格率分别为97.4%、90.9%;冷却水中嗜肺军团菌合格率为41.6%。结论海淀区部分酒店集中空调通风系统送风中空气细菌总数合格率较低,冷却水中嗜肺军团菌污染情况较为严重,应加强集中空调系统的清洗消毒和卫生监督管理。     

线粒体DNA突变和肿瘤发生

肿瘤细胞线粒体及线粒体DNA的研究已从形态学改变进展至分子水平的变化。由于近年来在多种肿瘤组织中发现了线粒体DNA的突变 ,而且线粒体DNA的突变率明显高于核基因 ,所以研究者们趋向认为线粒体DNA的突变与肿瘤发生密切相关。我们就近年来线粒体DNA突变与肿瘤关系的研究进展做一综述 ,以期探讨线粒体DNA突变在肿瘤发生中的作用     

Evaluating best management practices at an urban golf course

This three-year study evaluated the effects of best management practices (BMPs) in reducing surface water contamination at an urban golf course. Water samples were collected before BMP implementation from two ponds on Braeburn Golf Course (Wichita, KS, USA). The pesticides 2,4-dicholorodiphenoxyacetic acid (2,4-D) and simazine were periodically found at concentrations above recommended water quality criteria. Excessive nutrients in the form of nitrates and total phosphorus were also measured. In addition, an assessment of macroinvertebrate populations revealed only a few tolerant species. Beginning in year 2, recommendations to alter chemical applications on the course were implemented as part of the BMPs. Surface water sampling during year 2 showed significant declines in nitrate and total phosphorus levels; however, seasonal contamination from pesticides continued to occur. Beginning in year 3, structural changes to the golf course were made as part of the BMPs. Subsequent water sampling indicated further reductions of nitrates (80%) and total phosphorus (40 and 60% in the two ponds, respectively), and elimination of contamination from spring applications of 2,4-D and simazine. Finally, an assessment of macroinvertebrate populations indicated an improvement in taxa richness, as well as repopulation by less tolerant organisms. Results of this study can be used to develop and refine golf course management procedures to protect aquatic environments.     

Mercury patterns in wood duck eggs from a contaminated reservoir in South Carolina, USA

Mercury contamination of wildlife populations has been documented widely in recent years as biomonitoring has become an important tool for assessing environmental contamination. Avian eggs provide an ideal assay material for Hg biomonitoring, particularly when the collection of eggs is simplified by using cavity-nesting species that nest in easily monitored nest boxes. However, studies are needed that address the dynamics of how Hg is distributed within eggs, and how Hg is deposited naturally within clutches laid by a single female and among clutches laid by different females occupying the same contaminated environment. We collected 138 eggs from 13 complete clutches of box-nesting wood ducks (Aix sponsa) during 1991 and 1992 at a contaminated reservoir of the U.S. Department of Energy's Savannah River Site in South Carolina, USA. Total Hg residues in egg components and clutches were determined, partitioning of Hg among egg components was examined, and effects of egg-laying sequence on egg component Hg levels were determined. Mean albumen Hg was 0.22 ppm wet mass, mean yolk Hg was 0.04 ppm, and mean shell Hg was 0.03 ppm. On average, 86.1% of total egg Hg was concentrated in the albumen, 11.2% in the yolk, and 2.7% in the shell. Mercury concentrations in all egg components varied significantly among clutches and between successive clutches laid by the same female in the same year. Laying sequence significantly affected Hg concentrations in the albumen and shell, but not in the yolk. Declines of albumen Hg due to laying sequence were more pronounced for clutches that contained higher average Hg levels. Our results suggest that collection of first-laid eggs may be preferable for assessing maximal Hg exposure to developing embryos, and that monitoring Hg levels through the use of empty eggshells following brood departure from nests may be valid only if the laying sequence is known.     

Plutonium, Am, Cm and Sr in ducks maintained on radioactive leaching ponds in southeastern Idaho

Concentrations of 90Sr, 238Pu, 239,240Pu, 241Am, 242Cm and 244Cm were determined in tissues of mallard ducks (Anas platyrhynchos) maintained for 43-145 d on radioactive leaching ponds in southeastern Idaho. Highest concentrations of transuranics occurred in the gastrointestinal tract, followed closely by feathers. Approximately 75%, 18%, 6% and 1% of the total transuranic activity in tissues analyzed were associated with the bone, feathers, GI tract and liver, respectively. Concentrations in GI tracts were similar to concentrations in vegetation and insects in the littoral area of the ponds. The calculated total dose rate to the ducks from both 90Sr and the transuranic nuclides was 0.69 mGy d-1 (69 mrad d-1), of which 99% was to the bone. The potential effective dose equivalent to a human consuming the entire muscle and liver mass of one experimental duck with average nuclide concentrations was 0.46 microSv (0.046 mrem). Based upon average concentrations in experimental ducks and on surveys of wild waterfowl using this area, a conservative estimate of transuranic activity exported by wild ducks using the ponds during one year was 11.3 kBq (305 nCi). Similarly, the total amount of 90Sr exported in muscle, bone and lung of wild ducks in one year was 2.5 MBq (68.7 microCi).     

L-Arginine Reduces Nitro-Oxidative Stress in Cultured Cells with Mitochondrial Deficiency

L-Arginine (L-ARG) supplementation has been suggested as a therapeutic option in several diseases, including Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like syndrome (MELAS), arguably the most common mitochondrial disease. It is suggested that L-ARG, a nitric oxide (NO) precursor, can restore NO levels in blood vessels, improving cerebral blood flow. However, NO also participates in mitochondrial processes, such as mitochondrial biogenesis, the regulation of the respiratory chain, and oxidative stress. This study investigated the effects of L-ARG on mitochondrial function, nitric oxide synthesis, and nitro-oxidative stress in cell lines harboring the MELAS mitochondrial DNA (mtDNA) mutation (m.3243A>G). We evaluated mitochondrial enzyme activity, mitochondrial mass, NO concentration, and nitro-oxidative stress. Our results showed that m.3243A>G cells had increased NO levels and protein nitration at basal conditions. Treatment with L-ARG did not affect the mitochondrial function and mass but reduced the intracellular NO concentration and nitrated proteins in m.3243A>G cells. The same treatment led to opposite effects in control cells. In conclusion, we showed that the main effect of L-ARG was on protein nitration. Lowering protein nitration is probably involved in the mechanism related to L-ARG supplementation benefits in MELAS patients.     

邯郸地区健康体检人群线粒体DNA A1555G和C1494T突变分析

目的:调查邯郸地区健康体检人群线粒体DNA A1555G和C1494T突变的携带率,明确非综合征型耳聋患者发病的分子学基础。方法:对健康体检人群进行常见耳聋基因筛查内容的宣传,每个受检者抽取外周血并提取DNA,应于PCR对线粒体12SrRNA基因片段进行扩增,应用直接测序法分别对线粒体12SrRNA基因的2个基因片段进行直接测序。结果:①2 308名健康体检人群中,2 000名同意进行常见耳聋基因筛查,接受率达86.96%。②PCR检测结果:以2 000例研究对象的DNA样本进行线粒体12SrRNA基因的2个基因片段扩增,扩增产物片段大小与预期相符。③测序结果:被检测的2 000例研究对象中,3例(占0.15%)携带线粒体12SrRNA基因A1555G点突变,其中男性1例,女性2例;1例男性(占0.05%)携带线粒体12SrRNA基因C1494T点突变。结论:常见耳聋基因筛查在健康体检人群中接受程度高,如列入常规的体检项目中,可以用于早期诊断,遗传咨询和指导该家系成员预防药物性耳聋,可以有效避免高危人群出现耳聋。     

Mutagenicity and genotoxicity of coal fly ash water leachate

Fly ash is a by-product of coal-fired electricity generation plants. The prevalent practice of disposal is as slurry of ash and water to storage or ash ponds located near power stations. This has lain to waste thousands of hectares of land all over the world. Since leaching is often the cause of off-site contamination and pathway of introduction into the human environment, a study on the genotoxic effects of fly ash leachate is essential. Leachate prepared from the fly ash sample was analyzed for metal content, and tested for mutagenicity and genotoxicity. Analyses of metals show predominance of the metals-sodium, silicon, potassium, calcium, magnesium, iron, manganese, zinc, and sulphate. The Ames Salmonella mutagenicity assay, a short-term bacterial reverse mutation assay, was conducted on two-tester strains of Salmonella typhimurium strains TA97a and TA102. For genotoxicity, the alkaline version of comet assay on fly ash leachate was carried in vitro on human blood cells and in vivo on Nicotiana plants. The leachate was directly mutagenic and induced significant (P<0.05) concentration-dependent increases in DNA damage in whole blood cells, lymphocytes, and in Nicotiana plants. The comet parameters show increases in tail DNA percentage (%), tail length (mum), and olive tail moment (arbitrary units). Our results indicate that leachate from fly ash dumpsites has the genotoxic potential and may lead to adverse effects on vegetation and on the health of exposed human populations.     

The effects of changing atmospheric oxygen concentrations and background radiation levels on radiogenic DNA damage rates.

Both background radiation levels and atmospheric oxygen concentrations have changed dramatically over the history of life on earth. Because oxygen has a strong modifying influence on radiogenic mutation rates, these factors must be considered jointly to determine changes in radiogenic mutation rates over time. Using accepted models that describe how both of these parameters have changed through time, we find that radiogenic mutation rates in organisms have fluctuated between about 1.5 to 2.5 times current levels through most of the history of life. The results of this study have interesting implications that may impact our understanding of how modern organisms respond to radiation damage and of models that use molecular clocks to date species divergence times. It is also possible that changing oxygen levels have served to buffer mutation rate changes that result from changes in background radiation levels over time.     

Mallard reproductive testing in a pond environment: A preliminary study

A 2-year preliminary study was conducted on mallard ducks (Anas platyrhynchos), to determine the feasibility of using outdoor pond enclosures for reproductive studies and to evaluate the effects of the insecticide chlorpyrifos on mallard reproduction. No significant reproductive effects were observed for mallards receiving 8 ppm (mg/kg of feed) chlorpyrifos in their diet. Birds receiving 80 ppm chlorpyrifos hatched significantly (p < 0.05) fewer ducklings per successful nest (5.8) than controls (10.2). None of the ducklings on treatment ponds survived to 7 days. Control birds produced 8.4 ducklings per successful nest surviving to 7 days or longer. Birds in the 80 ppm treatment group consumed less feed than did controls (p < 0.01). Weight loss from reduced feed consumption did not occur to the extent expected, indicating that birds supplemented their diets with natural foods found in and around the ponds. In spite of relatively low treated feed consumption, brain acetylcholinesterase was significantly (p < 0.05) depressed (57% of controls) for 80 ppm treated birds. Studies on indoor penned mallards fed 80 ppm chlorpyrifos in their diet also resulted in acetylcholinesterase depression to the same extent, but at much higher feed consumption levels. The study demonstrated the potential of using outdoor pond enclosures to evaluate chemical effects on food consumption, brain acetylcholinesterase, and reproduction in mallards. Improvements to the study design and to the pond enclosures are discussed.