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431.
Alteration of DNA methylation is a major epigenetic mechanism associated with the effects of nongenotoxic carcinogens. We evaluated the effects of two environmental pollutants, hexabromocyclododecane (HBCD), 17-beta oestradiol (E(2)) as well as 5-aza 2' deoxycytidine (5AdC) on global DNA methylation levels (5-methyl 2' deoxycytidine) in the liver and gonads of the three-spine stickleback (Gasterosteus aculeatus). HBCD at 30 and 300 ng/L of water did not produce statistically significant differences in global genomic methylation in liver of female stickleback. On the other hand, the methylation inhibitor, 5-aza-2'-deoxycytidine, significantly lowered hepatic global methylation levels in these fish by 14% (P<0.05). The naturally occurring oestrogen, 17-beta oestradiol (E(2)) at 100 ng/L also decreased global DNA methylation levels in female liver but this effect was not statistically significant. In contrast, both E(2) and 5AdC caused statistically significant (P<0.001 and P<0.01 respectively) global genomic hypermethylation in the gonads of male sticklebacks although the increase seen in the female gonads was not statistically significant. The male gonad effect though unexplained may potentially be an indirect response to hypomethylation in other tissues (such as the liver) and may have important implications regarding oestrogenic effects in fish. The contrasting effects of HBCD and E(2) on global DNA methylation in stickleback should contribute to the integrated risk assessment of these environmental chemicals. 相似文献
432.
Recent studies on climate responses in ectothermic (cold-blooded) vertebrates have been few in number and focussed on phenology
rather than morphology. According to Bergmann’s rule, endothermic (warm-blooded) vertebrates from cooler climates tend to
be larger than congeners from warmer regions. Although amphibians are ectothermic vertebrates, weather and climatic conditions
may also impact on their morphology, and thereby affect their survival rates and population dynamics. In this paper, we show,
in a unique long-term study during the period 1963–2003 in an agricultural landscape in western Poland, that the body length
of two water frog parental species (males of both Rana ridibunda and R. lessonae) increased significantly. However, their hybridogenetic hybrid R. esculenta did not show similar changes. A significant relationship with a large-scale climatic factor, the winter North Atlantic Oscillation
index, was found positive for R. ridibunda males and R. lessonae females, and negative for R. esculenta females. Our findings, the first for amphibians, are consistent with other studies reporting that recent climate change has
affected the morphology of animals. However, we also show that changes in amphibian phenotype linked to climate may vary independently
between (even very similar) species. 相似文献
433.
Population growth rate and carrying capacity for springtails Folsomia candida exposed to ivermectin.
Helen L No?l Steve P Hopkin Thomas H Hutchinson Tim D Williams Richard M Sibly 《Ecological applications》2006,16(2):656-665
Forecasting the effects of stressors on the dynamics of natural populations requires assessment of the joint effects of a stressor and population density on the population response. The effects can be depicted as a contour map in which the population response, here assessed by population growth rate, varies with stress and density in the same way that the height of land above sea level varies with latitude and longitude. We present the first complete map of this type using as our model Folsomia candida exposed to five different concentrations of the widespread anthelmintic veterinary medicine ivermectin in replicated microcosm experiments lasting 49 days. The concentrations of ivermectin in yeast were 0.0, 6.8, 28.8, 66.4, and 210.0 mg/L wet weight. Increasing density and chemical concentration both significantly reduced the population growth rate of Folsomia candida, in part through effects on food consumption and fecundity. The interaction between density and ivermectin concentration was "less-than-additive," implying that at high density populations were able to compensate for the effects of the chemical. This result demonstrates that regulatory protocols carried out at low density (as in most past experiments) may seriously overestimate effects in the field, where densities are locally high and populations are resource limited (e.g., in feces of livestock treated with ivermectin). 相似文献
434.
Walker TR Habeck JO Karjalainen TP Virtanen T Solovieva N Jones V Kuhry P Ponomarev VI Mikkola K Nikula A Patova E Crittenden PD Young SD Ingold T 《Ambio》2006,35(5):220-228
Using interdisciplinary field research in the Usa Basin, northeast European Russia, we compared local inhabitants' perception of environmental problems with chemical and remote-sensing signatures of environmental pollution and their local impacts. Extensive coal mining since the 1930s around Inta and Vorkuta has left a legacy of pollution, detected by measuring snowpack, topsoil, and lichen chemistry, together with remote-sensing techniques and analysis of lake water and sediments. Vorkuta and its environs suffered the worst impacts, with significant metal loading and alkalization in lakes and topsoils, elevated metals and cations in terricolous (reindeer) lichens, and changes in vegetation communities. Although the coal industry has declined recently, the area boasts a booming oil and gas industry, based around Usinsk. Local perceptions and concerns of environmental pollution and protection were higher in Usinsk, as a result of increased awareness after a major oil spill in 1994, compared with Vorkuta's inhabitants, who perceived air pollution as the primary environmental threat. Our studies indicate that the principal sources of atmospheric emissions and local deposition within 25 to 40 km of Vorkuta were coal combustion from power and heating plants, coal mines, and a cement factory. Local people evaluated air pollution from direct observations and personal experiences, such as discoloration of snow and respiratory problems, whereas scientific knowledge played a minor role in shaping these perceptions. 相似文献
435.
Nonstructural Urban Stormwater Quality Measures: Building a Knowledge Base to Improve Their Use 总被引:1,自引:0,他引:1
This article summarizes a research project that investigated the use, performance, cost, and evaluation of nonstructural measures
to improve urban stormwater quality. A survey of urban stormwater managers from Australia, New Zealand, and the United States
revealed a widespread trend of increasing use of nonstructural measures among leading stormwater management agencies, with
at least 76% of 41 types of nonstructural measures being found to be increasing in use. Data gathered from the survey, an
international literature review, and a multicriteria analysis highlighted four nonstructural measures of greatest potential
value: mandatory town planning controls that promote the adoption of low-impact development principles and techniques; development
of strategic urban stormwater management plans for a city, shire, or catchment; stormwater management measures and programs
for construction/building sites; and stormwater management activities related to municipal maintenance operations such as
maintenance of the stormwater drainage network and manual litter collections. Knowledge gained on the use and performance
of nonstructural measures from the survey, literature review, and three trial evaluation projects was used to develop tailored
monitoring and evaluation guidelines for these types of measure. These guidelines incorporate a new evaluation framework based
on seven alternative styles of evaluation that range from simply monitoring whether a nonstructural measure has been fully
implemented to monitoring its impact on waterway health. This research helps to build the stormwater management industry’s
knowledge base concerning nonstructural measures and provides a practical tool to address common impediments associated with
monitoring and evaluating the performance and cost of these measures. 相似文献
436.
Vagisha Pruthi Nimrah Abbasi Varsha Thakur Shiri Shinar Anne O’Connor Rachel Silver Tasha Simpson Tim Van Mieghem 《黑龙江环境通报》2023,43(7):881-888