Elevated 5-hydroxymethycytosine and cell apoptosis induced by tetrachloro-1,4-benzoquinone in mouse embryonic stem cells

<正>Pentachlorophenol(PCP)has been extensively used as a fungicide,bactericide,herbicide,molluscicide。algaecide and insecticide worldwide(Ahlborg and Thunberg,1980:Choudhury et al.,1986).Although PCP is primarily used as a preservative for wood and wood products,it has been also used in a variety of other products,including adhesives,construction materials,leather and paper.PCP is environmentally persistent with a half-life of up to 6-7 months in soil and water systems(Law     

Solar- und Windenergie zum Pumpen von Wasser

Water pumping by means of wind and solar energy becomes more and more attractive by reason of increasing energy prices. Water supply for remote villages especially in developing countries needs hydraulic energy of about 1 to 50 kWh per day. The use of renewable energies like solar and wind seems to be technically successfull and has a good chance to be competitive with conventional energy sources like diesel or electricity in regions with mean wind speeds above 4–5 m/s or high insolation of about 5 kWh/day annual average.     

1971～1997年香港城市代谢的上升趋势

城市代谢是一个城市对其自然环境负荷的定量描述。1971年ewcombe等[3]对香港的城市代谢进行了开创性的研究，我们在此基础上，对资源消耗和废弃物再生利用进行了更进一步的深入研究。从20世纪70年代早期开始，香港的人均粮食、水和物质消耗已经以惊人的速度分别增长了20％，40％和149％。在物质财富不断增长的同时，巨大的污染也随之而来，废气总排放量、CO2浓度、城市固体废弃物以及污水排放也分别增长了30％、250％、245％和153％，因此出现了一系列土地、大气和水系统超负荷的问题。尽管一些旨在治理退化环境的措施已经取得了成功，但是，政府为香港制定的目标是在21世纪成为"一个真正可持续发展的城市"，如果要达到这一目标，我们还需要在大众消费行为和政府政策方面进行重大和深远的改进。     

Lethal and sublethal effects of naphthalene and 1,2-dimethylnaphthalene on the marine copepod <Emphasis Type="Italic">Paracartia grani</Emphasis>

Here we evaluate the effects of two quantitatively very important components of the water soluble fractions of fuel oils (naphthalene and 1,2-dimethylnaphthalene, hereafter NAPH and C2-NAPH, respectively) on the survival, feeding and egg production rates, and viability of eggs of the coastal copepod Paracartia (Acartia) grani. Acute toxicity responses resulted in lethal concentrations (LC50) of 2,535 and 161 μg l⁻¹ for NAPH and C2-NAPH, respectively, with no evidence of narcotic effects. Hydrocarbon-specific differences in the toxicity response indicate that sublethal effects (EC50) on feeding by C2-NAPH were likely driven by induced mortality, whereas NAPH has direct negative effects on feeding. Sublethal effects on egg production rates followed a similar detrimental pattern to the one exhibited by feeding rates, suggesting that the lower egg production rates were mediated by the decrease in feeding rates. At the exposure time tested (24 h), the 50% reduction effective concentrations (EC50) determined for sublethal effects were relatively high in comparison with hydrocarbons’ concentrations found under natural circumstances. Long exposure (4 days) of P. grani adults to the tested hydrocarbons at concentrations well below the recorded EC50, however, had no significant effects on feeding, egg production and hatching rates. The viability of the eggs was either not affected or only slightly influenced when healthy eggs were incubated under very high concentrations (up to 6,400 and 700 μg l⁻¹ NAPH and C2-NAPH, respectively). The significance of the effects of oil spills on marine zooplankton communities is discussed in light of the results presented in this study.     

Trophic impact, metabolism, and biogeochemical role of the marine cladoceran Penilia avirostris and the co-dominant copepod Oithona nana in NW Mediterranean coastal waters

In this work we studied the trophic ecology and feeding impact of the cladoceran Penilia avirostris and the cyclopoid copepod Oithona nana, the two dominant zooplankters in the summer communities of the coastal NW Mediterranean, on the naturally occurring microbial communities. In order to ascertain carbon surplus for growth and reproduction and the contribution to carbon and nitrogen recycling of these two species, we also determined their basal metabolism and excretion rates. The experiments conducted during summers 2002, 2003, and 2004 indicate that P. avirostris grazed mostly upon small flagellates, dinoflagellates, and diatoms, whereas O. nana had a narrower prey range, selecting motile organisms such as ciliates and occasionally dinoflagellates. The grazing impact of both species accounted, on average, for <10% of the standing stock of the microbial groups considered. In spite of the oligotrophic conditions, the feeding activity of P. avirostris is in general sufficient to compensate basal metabolism and allows a surplus for growth and reproduction. This was not the case for O. nana, its daily rations being often lower than the carbon basal demands. Regarding excretion rates, both species presented different N:P excretion ratios, the ones of O. nana falling within values typical for copepods, whereas the absence of detectable phosphorus excretion by P. avirostris implied an unbalance recycling with respect to typical Redfield ratio composition of marine seston.