草甘膦对青鳉鱼卵黄蛋白原的诱导及其潜在分子机理

为了研究草甘膦潜在的雌激素效应,将1~3d的雌雄青鳉幼鱼暴露于不同浓度 (0.2, 2, 20, 200, 2000μg/L)的草甘膦5周,发现雌雄鱼肝脏卵黄蛋白原(VTG I)基因表达分别在0.2, 2, 20μg/L浓度(雌鱼)和2, 20, 200μg/L浓度(雄鱼)下受到显著诱导,但在高浓度下(雌鱼,200μg/L和2000μg/L;雄鱼,2000μg/L)恢复到正常水平.草甘膦诱导雌激素效应的机理存在雌雄差异:雌鱼中雌激素效应主要由于草甘膦诱导了脑部FSH和性腺CYP19A基因,从而增加了雌激素合成能力.雄鱼中主要由于草甘膦抑制肝脏中雌激素代谢酶 (CYP1A、CYP1B和CYP3A)而显示雌激素效应.     

鲫鱼(Carassius auratus)卵黄蛋白原的ELISA检测

采用Sephadex G-200柱层析从鲫鱼(Carassius auratus)成熟鱼卵中提取卵黄脂磷蛋白并制备抗卵黄脂磷蛋白抗血清.用DEAE-cellulose阴离子交换层析和Sephacryl S-300分子筛凝胶层析相结合的两步层析从经17b-雌二醇诱导的雌鱼血浆中提纯卵黄蛋白原.免疫印迹反应显示卵黄脂磷蛋白和卵黄蛋白原都与抗卵黄脂磷蛋白抗血清有特异的反应.以抗卵黄脂磷蛋白抗血清作为抗体,卵黄蛋白原作为竞争抗原建立了间接竞争法酶联免疫吸附反应(ELISA)方法来检测雄鱼血液中卵黄蛋白原含量.该方法可测的最低浓度为7.8ng/mL,工作范围为0.39~25mg/mL,批内和批间误差分别为6.5%和7.5%.     

天津野生鲫鱼卵黄蛋白原的研究

用HPLC方法提纯经雌二醇诱导的鲫鱼卵黄蛋白原,用SDS-PAGE凝胶电泳测定其分子量为160Kda左右.在建立卵黄蛋白原(VTG)的HPLC分析方法(检测下限为0.025mg/mL)的基础上,对北京排污河天津段的野生和养殖鲫鱼血浆中的VTG进行检测.在所捕获的12尾野生鲫鱼中(其中2尾为雄性鲫鱼),都检测出了VTG,浓度范围为0.284～5.971mg/mL;对同期捕获的35尾天津养殖鲫鱼包括1尾雄性鲫鱼中的VTG也进行了检测,浓度范围为0.119～0.250mg/mL.而同期在实验室饲养的雌雄鲫鱼血浆中,均未检测出VTG.结果表明,北京排污河(天津段)的野生鲫鱼受到类雌激素物质的污染.     

RNAi-mediated silencing of vitellogenin gene function turns honeybee (Apis mellifera) workers into extremely precocious foragers

The switch from within-hive activities to foraging behavior is a major transition in the life cycle of a honeybee (Apis mellifera) worker. A prominent regulatory role in this switch has long been attributed to juvenile hormone (JH), but recent evidence also points to the yolk precursor protein vitellogenin as a major player in behavioral development. In the present study, we injected vitellogenin double-stranded RNA (dsVg) into newly emerged worker bees of Africanized genetic origin and introduced them together with controls into observation hives to record flight behavior. RNA interference-mediated silencing of vitellogenin gene function shifted the onset of long-duration flights (>10 min) to earlier in life (by 3–4 days) when compared with sham and untreated control bees. In fact, dsVg bees were observed conducting such flights extremely precociously, when only 3 days old. Short-duration flights (<10 min), which bees usually perform for orientation and cleaning, were not affected. Additionally, we found that the JH titer in dsVg bees collected after 7 days was not significantly different from the controls. The finding that depletion of the vitellogenin titer can drive young bees to become extremely precocious foragers could imply that vitellogenin is the primary switch signal. At this young age, downregulation of vitellogenin gene activity apparently had little effect on the JH titer. As this unexpected finding stands in contrast with previous results on the vitellogenin/JH interaction at a later age, when bees normally become foragers, we propose a three-step sequence in the constellation of physiological parameters underlying behavioral development. David Santos Marco Antonio and Karina Rosa Guidugli-Lazzarini contributed equally to the present study.     

雌二醇、壬基酚和三丁基锡对草金鱼血浆卵黄蛋白原含量的联合效应

雌二醇(17β-estradiol,E2)是生物合成的天然雌激素,壬基酚(nonylphenol,NP)和三丁基锡(tributyltin,TBT)则是人工合成的环境拟雌激素和环境抗雌激素,这3种污染物在自然水体中均广泛分布,给多种水生生物的健康造成威胁,然而其共同存在下的联合效应尚不明确.本文以草金鱼(Carassius auratus)为受试生物,以鱼体血浆中卵黄蛋白原浓度为观测指标,研究雌二醇和壬基酚的雌激素活性及三丁基锡的抗雌激素活性.在单独暴露实验的基础上,研究3种污染物两两联合及三者联合条件下对雄性草金鱼卵黄蛋白原的联合诱导效应.结果表明,雌二醇和壬基酚均能显著诱导雄性草金鱼合成卵黄蛋白原,三丁基锡对雄性和雌性草金鱼卵黄蛋白原含量均无显著影响.雌二醇和壬基酚共暴露时,壬基酚能促进雌二醇的雌激素效应;雌二醇与三丁基锡共暴露时,后者可抑制雌二醇的雌激素效应;3种污染物共同暴露时,三丁基锡也表现为抗雌激素效应.但壬基酚与三丁基锡共暴露时,后者未能抑制壬基酚的雌激素效应.上述结果表明天然雌激素、拟雌激素和抗雌激素之间存在复杂的联合效应,拟雌激素和抗雌激素的毒性效应并非简单地相互抵消,因此在生态风险评价时需全面评估不同类型环境雌激素之间的复合效应.     

Combined effect of tributyltin and benzo[a] pyrene on the levels of sex hormone and vitellogenin in female Sebastiscus marmoratus

Tributyltin（TBT）, an organometal used as an antifouling biocide, has been reported to induce masculinization of fish. Benzo [a]pyrene （BaP）, a widespread carcinogenic polycyclic aromatic hydrocarbon, has been reported that its microsomal metabolites can produce an estrogenic response when tested in vitro. This study was therefore designed to examine the potential in vivo influence of TBT, BaP and their mixture on sex hormone levels in serum of Sebastiscus marmoratus, which were given 2 separate intraperitoneally （ip） injections（a single injection every 7 d） of TBT（0.5, 1, 5 and 10 mg/kg）, BaP（0.5, 1, 5 and 10 mg/kg）, or both in combination（0.5, 1, 5 and 10 mg/kg）; control fish received olive oil vehicle only. Six days after the 2nd injection, serum samples were collected and analyzed for sex hormone levels and alkali labile protein phosphorus （ALPP）, which is related to the yolk precursor protein vitellogenin. The pollutants at all doses significantly reduced serum testosterone, estradiol and ALPP content after 2 injections compared with the corresponding controls. The reduction of the estradiol levels should be response for the decrease of the vitellogenin levels. The results in the present study suggested that aromatase seems not the major target acted by TBT and BaP in fish. This study demonstrated that TBT or BaP exposure both inhibit the reproductive potential in female Sebastiscus marmoratus. Combined effect of TBT and BaP on the serum testosterone, estradiol and ALPP was not antagonism from the anticipation.     

Assessing the anti-estrogenic activity of sodium pentachlorophenol in primary cultures of juvenile goldfish (Carassius auratus) hepatocytes using vitellogenin as a biomarker

Both pentachlorophenol and 2,3,7,8-tetrachlorodibenzo-p-dioxin （TCDD） had been studied widely because of their probable anti-estrogenic activity. Sodium pentachlorophenol （PCP-Na）, as a industrial product used in many fields, usually contains a trace of TCDD. The aim of this study was to assess the anti-estrogenic effect of PCP-Na in juvenile goldfish （Gurassius auratus） hepatocyte cultures using vitellogenin （VTG） as the biomarker. The ID50 of PCP-Na was investigated and then a series of concentrations （0.001 0.5 μg/ml） of PCP-Na were evaluated to estimate the anti-estrogenic activity. Results showed that PCP-Na was cytotoxic for hepatocytes even at very low concentration 〈1.21 μg/ml, and it could not induce VTG at any concentrations tested. Since it failed to stimulate VTG production, the possibility of its anti-estrogenic effect was tested, and a well-known anti-estrogenic compound-tamoxifen was used as positive control. PCP-Na caused a reduction in VTG synthesis in juvenile goldfish （Carassius auratus） hepatocytes at concentrations 〉0.1μg/ml when co-exposure with 1μg/ml 17β-estradiol （E2）, making its anti-estrogenic activity approximately as potent as tamoxifen. Our results indicate that PCP-Na can act as negative modulators of estrogenic function in juvenile goldfish （Carassius auratus） hepatocytes.     

Attempts to train goldfish to respond to magnetic field stimuli

Two different conditioning procedures, one appetitive and the other aversive, were used in separate attempts to demonstrate response to magnetic fields in the goldfish, Carassius auratus. Our results lead us to question those of an orientation experiment by Becker, although we recognize the possibility that goldfish may be sensitive primarily to magnetic field direction rather than intensity and that their directional sensitivity may be evidenced most readily by orientation in the field.     

从生态旅游到低碳旅游——从理念到实践

阐述了生态旅游、低碳旅游的基本概念,分析了生态旅游存在的不足,提出低碳旅游的量化及建立各项标准及其指标评价体系并将之融入低碳旅游全过程以实现低碳旅游的标准化,重点在于实现低碳理念、低碳参与者及低碳实践3个方面的有机结合,以促进旅游业的可持续发展的可操作性建议.     

以学定教,提高课堂教学效率

根据心理学理论,学习是一个学生内化的过程,学生是自主学会的,而不是被动教会的。因此在教学中,教师只有做到以学定教,才能有效提高教学效率,促进学生对知识的掌握。     

如何做好突发环境事件应急监测的快速响应

应急监测是突发性环境污染事故处置中的首要环节,是对污染事故及时、正确地进行应急处理、减轻事故危害和制定恢复措施的根本依据。文章从制定应急监测预案、加强应急监测能力建设、摸清污染源状况、加强应急培训和应急演练等方面对做好突发环境事件应急监测的快速响应作了简要的阐述,供大家探讨。     

Croppers to livestock keepers: livelihood transitions to 2050 in Africa due to climate change

The impacts of climate change are expected to be generally detrimental for agriculture in many parts of Africa. Overall, warming and drying may reduce crop yields by 10–20% to 2050, but there are places where losses are likely to be much more severe. Increasing frequencies of heat stress, drought and flooding events will result in yet further deleterious effects on crop and livestock productivity. There will be places in the coming decades where the livelihood strategies of rural people may need to change, to preserve food security and provide income-generating options. These are likely to include areas of Africa that are already marginal for crop production; as these become increasingly marginal, then livestock may provide an alternative to cropping. We carried out some analysis to identify areas in sub-Saharan Africa where such transitions might occur. For the currently cropped areas (which already include the highland areas where cropping intensity may increase in the future), we estimated probabilities of failed seasons for current climate conditions, and compared these with estimates obtained for future climate conditions in 2050, using downscaled climate model output for a higher and a lower greenhouse-gas emission scenario. Transition zones can be identified where the increased probabilities of failed seasons may induce shifts from cropping to increased dependence on livestock. These zones are characterised in terms of existing agricultural system, current livestock densities, and levels of poverty. The analysis provides further evidence that climate change impacts in the marginal cropping lands may be severe, where poverty rates are already high. Results also suggest that those likely to be more affected are already more poor, on average. We discuss the implications of these results in a research-for-development targeting context that is likely to see the poor disproportionately and negatively affected by climate change.     

Soil microbial response to herbicides applied to glyphosate-resistant canola

Adoption of glyphosate-resistant canola (Brassica napus L.) has increased glyphosate applications to this crop, and concerns have been raised about unintended consequences of these multiple applications. A field trial was conducted to evaluate the effects of pre-seed and in-crop glyphosate and alternative herbicides on soil microbial community functional structure, diversity and biomass. Pre-seed treatments were 2,4-D, glyphosate and 2,4-D + glyphosate, and in-crop treatments were glyphosate applied once, glyphosate applied twice, ethalfluralin, ethalfluralin + sethoxydim + ethametsulfuron + clopyralid, and sethoxydim + ethametsulfuron. Rhizosphere and bulk soil was collected at flowering stage of canola and analyzed for bacterial community-level substrate utilization patterns and microbial biomass C (MBC). Where differences were significant, pre-seed application of both 2,4-D and glyphosate altered the functional structure and reduced the functional diversity of soil bacteria, but increased MBC. These effects were not necessarily concurrent. The reduction in functional diversity was due to reduction in evenness, which means that the soil where both pre-seed herbicides had been applied was dominated by only few functional groups. In 1 year, two in-crop applications of glyphosate also reduced the functional diversity of soil bacteria when applied after pre-seed 2,4-D, as did in-crop sethoxydim + ethametsulfuron following pre-seed glyphosate. Even though significant differences between herbicides were fewer than non-significant differences, i.e., there were no changes in soil microbial community structure, diversity or biomass in response to glyphosate or alternative herbicides applied to glyphosate-resistant canola in most cases, the observed changes in soil microbial communities could affect soil food webs and biological processes.     

亲近自然的一条捷径——向你推荐《生物多样性知识达人手册》

"它随处可见,从最大的海洋到最小的水坑,从最茂密的森林到最干旱的荒漠,从最富饶的沼泽到最高的山峰……它是一个活的银行账户,为人类全部事业和财富提供资本.它是什么?它就是……生物多样性." 翻开《生物多样性知识达人手册》的第一页,在"开头的话"中,你就能读到上面这一段饶有趣味的文字,让你不自觉地联想到我们所处的环境和我们赖以生存的地球.没错,这是一本新鲜出炉的、以生物多样性为主题的读物,用生动有趣的方式告诉你,什么是生物多样性?生物多样性为什么重要?你怎样才能保护好这个星球的生物多样性?     

Behavior toxicity to Caenorhabditis elegans transferred to the progeny after exposure to sulfamethoxazole at environmentally relevant concentrations

Sulfamethoxazole (SMX) is one of the most common detected antibiotics in the environment. In order to study whether SMX can a ect behavior and growth and whether these e ects could be transferred to the progeny, Caenorhabditis elegans was exposed at environmentally relevant concentrations for 24, 48, 72 and 96 hr, respectively. After exposure, the exposed parent generation (P0) was measured for behavior and growth indicators, which were presented as percentage of controls (POC). Then their corresponding unexposed progeny (F1) was separated and measured for the same indicators. The lowest POC for P0 after 96 hr-exposure at 100 mg/L were 37.8%, 12.7%, 45.8% and 70.1% for body bending frequency (BBF), reversal movement (RM), Omega turns (OT) and body length (BL), respectively. And F1 su ered defects with the lowest POC as 55.8%, 24.1%, 48.5% and 60.7% for BBF, RM, OT and BL, respectively. Defects in both P0 and F1 showed a time- and concentration-dependent fashion and behavior indicators showed better sensitivity than growth indicator. The observed e ects on F1 demonstrated the transferable properties of SMX. Defects of SMX at environmental concentrations suggested that it is necessary to perform further systematical studies on its ecological risk in actual conditions.     

浅谈如何做好孩子的入学准备

从幼儿园升入小学是孩子迈入知识殿堂的关键一步,也是孩子人生的一大转折。如何协助家长和教师,帮助孩子顺利实现这次转折是非常重要的。基于此目的,结合多年从事幼小教育工作的实际,并根据教育部颁布的《幼儿园教育指导纲要》精神,紧扣学前儿童的心理和学习特点,阐述如何让孩子在各方面得到系统的锻炼和提高,为顺利升入理想的小学、并尽快适应小学阶段的学习和生活做好准备。     

重归大自然——密西西比河之行

密西西比河是美国第一大河。它一路曲曲弯弯向着墨西哥湾蜿蜒流去．沿途形成广袤的洪泛平原,滋润着美国大陆41％的土地。水量也比美国其他河流都要多。密西西比河及其洪泛平原哺育着400多种野生动植物。北美地区40％的水禽都沿着密西西比河的路径迁徙。密西西比河对于美国。如同长江对于中国,无论从经济还是生物多样性保护等方面,其作用都是举足轻重。     

怎样上好《毛泽东思想概论》第一课

本文认为，如果能将“毛泽东思想概论”这一课程名分解为“毛泽东”“毛泽东思想”“毛泽东思想概论”3个概念，并逐一进行总体性、概括性讲解，对上好（《毛泽东思想概论》第一课，很有帮助。