Exposure to strange adults does not cause pregnancy disruption or infanticide in the gray-tailed vole

A widely accepted paradigm in mammalian behavioral biology is that exposure to unfamiliar males causes pregnancy disruption in female rodents (commonly known as the Bruce effect). This behavioral phenomenon has been demonstrated in the laboratory with at least 12 species of rodents, primarily within the genus Microtus, and is supposedly an adaptation that provides male perpetrators with reproductive access to females, and functions, for females, as a counterstrategy to infanticide. However, neither the Bruce effect nor its adaptive significance have been tested experimentally in the field. In a controlled field study, we exposed reproducing female gray-tailed voles (Microtus canicaudus) to treatments in which males were removed and replaced by either unfamiliar males or females, and found no significant differences in intervals between parturitions, number of pregnancies, and juvenile recruitment among the treatment and control animals. Thus, we conclude that neither the Bruce effect nor infanticide occurred differentially as a consequence of the treatments in gray-tailed voles. Multimale mating to confuse paternity, and postpartum estrus resulting in simultaneous pregnancy and lactation may deter infanticide and functionally negate any benefits of pregnancy disruption in gray-tailed voles and perhaps other murid rodents with similar mating systems. In light of our results, we recommend field verification for other species of murid rodents that exhibit the Bruce effect in the laboratory before the results are applied to evolutionary theory. Received: 12 May 1998 / Accepted after revision: 6 September 1998     

Whole effluent toxicity assessment at a wastewater treatment plant upgraded with a full-scale post-ozonation using aquatic key species

Ozonation as final wastewater (WW) polishing step, following conventional activated sludge treatment is increasingly implemented in sewage treatment for contaminant degradation to prevent surface water pollution. While the oxidative degradation of chemicals has been extensively investigated, the in vivo toxicological characteristics of ozonated whole effluents are rarely a matter of research.In the present study, whole effluents were toxicologically evaluated with an in vivo test battery before and after full-scale ozonation and subsequent sand filtration on site at a treatment plant. One aquatic plant (duckweed, Lemna minor) and five invertebrate species of different systematic groups (Lumbriculus variegatus, Chironomus riparius, Potamopyrgus antipodarum, Daphnia magna) were exposed to the effluents in a flow-through-designed test system with a test duration of 7-28 d.None of the considered toxicity endpoints correlated with the pollutant elimination. A tendency towards an increased toxicity after ozonation was apparent in three of the test systems showing [statistically] significant adverse effects in the L. variegatus toxicity test (decrease in reproduction and biomass). After sand filtration, adverse effects were reduced to a similar level like after conventional treatment. Solely the Daphnia reproduction test revealed beneficial effects after ozonation in combination with sand filtration.Results of the test battery indicate the formation of adverse oxidation products during WW ozonation. L. variegatus appeared to be the most sensitive of the five test species. Sand filtration effectively removes or detoxifies toxic oxidation products, as toxic effects were subsequently reduced to the level after conventional treatment.     

Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) and phenolic endocrine disrupting chemicals in South and Southeast Asian mussels

A comprehensive monitoring survey for polycyclic aromatic hydrocarbons (PAHs) and phenolic endocrine disrupting chemicals (EDCs) utilizing mussels as sentinel organisms was conducted in South and Southeast Asia as a part of the Asian Mussel Watch project. Green mussel (Perna viridis) samples collected from a total of 48 locations in India, Indonesia, Singapore, Malaysia, Thailand, Cambodia, Vietnam, and the Philippines during 1994–1999 were analyzed for PAHs, EDCs including nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA), and linear alkylbenzenes (LABs) as molecular markers for sewage. Concentrations of NP ranged from 18 to 643 ng/g-dry tissue. The highest levels of NP in Malaysia, Singapore, the Philippines, and Indonesia were comparable to those observed in Tokyo Bay. Elevated concentrations of EDCs were not observed in Vietnam and Cambodia, probably due to the lower extent of industrialization in these regions. No consistent relationship between concentrations of phenolic EDCs and LABs were found, suggesting that sewage is not a major source of EDCs. Concentrations of PAHs ranged from 11 to 1,133 ng/g-dry, which were categorized as “low to moderate” levels of pollution. The ratio of methylphenanthrenes to phenanthrene (MP/P ratio) was >1.0 in 20 out of 25 locations, indicating extensive input of petrogenic PAHs. This study provides a bench-mark for data on the distribution of anthropogenic contaminants in this region, which is essential in evaluating temporal and spatial variation and effect of future regulatory measures.     

北黄海近岸海域生物体中酚类内分泌干扰物富集与放大作用研究

在北黄海近岸海域21个典型区域采集了可构成3个营养级的6种生物样品,分别为海带、裙带菜、牡蛎、扇贝、海参和黑鱼.采用HPLC-MS/MS检测6种生物样品中双酚A(BPA)、辛基酚(0P)、壬基酚(NP)、2,4-二氯酚(2,4-DCP)、对叔丁基苯酚(PTBP)和对特辛基苯酚(POP)质量比,并进一步采用生物富集因子(BAF)和生物放大因子(TMF)评价了北黄海近岸海域生物体内酚类内分泌干扰物的富集作用与放大能力.结果表明,北黄海近岸海域生物体中6种酚类内分泌干扰物的质量比范围为检出限(nd)～1 796.26 ng/g,其中2,4-二氯酚具有较强的生物富集效应,辛基酚和壬基酚具有潜在的生物富集效应,同时营养级越高,生物放大作用越明显.研究表明,海洋生物体对酚类内分泌干扰物的富集能力随营养级升高而增大.     

苯并芘对稀有鮈鲫的内分泌干扰效应研究

为评价典型有机污染物对长江三峡库区上游特有珍稀鱼类的环境风险,本实验以稀有鮈鲫为对象,研究了低剂量多环芳烃(PAHs)暴露而引起的内分泌干扰效应.将成年稀有鮈鲫暴露于不同浓度(0、0.1、0.3、1.0和3.0μg·L-1)的苯并芘(Ba P)中28 d,测定了体质系数、性激素含量、下丘脑-垂体-性腺(HPG)轴和肝脏中与繁殖相关基因的表达.结果显示:在雌鱼中,Ba P暴露后,睾酮(T)的含量显著升高,雌二醇(E2)的水平显著下降并改变了T/E2的比值;在雄鱼中,T和E2的含量都显著下降.雌雄鱼性激素的改变可能与类固醇合成相关基因(Cyp17、Cyp19a)表达量的改变有关.Ba P暴露显著抑制了雌雄鱼肝脏中卵黄蛋白原(VTG)基因的表达.以上检测到的激素或者基因表达的改变主要发生在高剂量(3.0μg·L-1)Ba P暴露下,而长江上游库区水体中多环芳烃含量较低(100 ng·L-1),因此推测,库区存在的多环芳烃不会对三峡库区上游水体中的鱼类产生内分泌干扰效应.     

超高效液相色谱-串联质谱法同时分析地下水中24种内分泌干扰物

建立了基于超高效液相色谱-串联质谱法同时测定地下水中9种雌激素、5种雄激素、3种肾上腺皮质激素、4种酚类和3种非甾类激素共24种内分泌干扰物的方法。在活化后的MCX固相萃取柱中加入水样,再加入pH=5的水溶液淋洗,随后用碱化乙腈(4.5%,体积分数)洗脱。收集洗脱液并用氮气吹至近干后,用甲醇定容。采用Poroshell 120 Bonus-RP色谱柱(2.7 μm,100 mm×2.1 mm),以0.1%氨水溶液-乙腈为流动相进行梯度洗脱,实现液相分离。质谱检测采用MRM模式进行采集,通过正负离子模式切换同时进行测定,使用内标法定量。检测结果显示,目标物在线性范围内,决定系数R²均大于0.995,方法检出限为0.05~2.00 ng/L,加标回收率为68.8%~108%。该方法灵敏度高、准确度好,具有较强的实用价值。     

壬基酚的环境生物地球化学研究进展及对新污染物管理的建议

近年来,我国大气环境、水环境和土壤环境质量得到一定的改善,“碧水蓝天”已经成为常态.但随着持久性有机污染物、内分泌干扰物、抗生素和微塑料等新污染物在环境中不断被检出,新污染物正逐步受到广泛的关注,壬基酚作为一种典型的内分泌干扰物也备受研究人员的关注.系统地概括了我国水体中壬基酚的环境行为和暴露水平,并基于风险商法和联合概率曲线法对壬基酚可能造成的生态风险进行了评估.结果表明,壬基酚对水生生物的毒性效应主要包括急性毒性、生长发育毒性、雌激素效应和繁殖毒性;壬基酚在我国主要流域水体中普遍存在,其浓度平均值在60～1 000 ng·L^-1,浓度最高值可达4 628 ng·L^-1;基于风险商法和联合概率曲线法的风险评估结果表明,壬基酚对我国主要流域里的水生生物均存在一定的风险.最后,总结了目前比较常用的壬基酚处理处置和风险管控技术,比较了国际上内分泌干扰物的监管方法,针对我国在新污染物环境管理中存在的问题,提出了针对性政策建议,研究结果可以为我国新污染物管理和管控提供参考.     

Zebrafish embryos/larvae for rapid determination of effects on hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-interrenal (HPI) axis: mRNA expression

To identify and prioritize chemicals that may affect thyroid and adrenal/interregnal endocrine system and to reduce cost and animal use by conventional toxicity assay, an in vivo screening assay was developed using zebrafish embryos/larvae based on measurement of expression of genes that were suggested to play important roles in hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-interrenal (HPI) axis. Model chemicals that could modulate HPT and HPI axis in adult fish were selected in assay validation, including anti-thyroid agent 6-Propyl-2-thiouracil (PTU) and cytochrome P450 11B (Cyp11b) enzyme inhibitor metyrapone (MET). Zebrafish embryos were exposed to different concentrations of model chemical from 4 h post-fertilization (hpf) to 5 d post-fertilization (dpf). Exposure to PTU increased mRNA expression of sodium iodide symporter (nis) and thyroglobulin (tg) involved in HPT axis, and MET treatment up-regulated all the mRNA expression tested involved in HPI axis by a compensatory mechanism. These results suggested that HPT and HPI axis were active upon chemical exposure at least at 5 dpf zebrafish. Furthermore, we studied the effects of PTU or MET on the cross-talk between HPT and HPI axis. The results demonstrated that PTU and MET could affect cross-talk responses in zebrafish embryos/larvae.     

In vivo endocrine effects of naphthenic acids in fish

Oil pollution from various sources, including exploration, production and transportation, is a growing global concern. The highest toxicity of hydrocarbon pollutants is associated with the water-soluble phase compounds, including naphthenic acids, a known component found in all hydrocarbon deposits. Recently, naphthenic acids (NAs) have shown estrogenic and anti-androgenic effects in vitro. For this reason we investigated the potential effects of two commercial mixtures of naphthenic acids on fish in vivo, using the three-spined stickleback (Gasterosteus aculeatus) as a model species.