Chemopreventive effects of ellagic acid against genotoxicity induced by benzo(a)pyrene

Benzo(a)pyrene (B(a)P) is a commonly used indicator for polycyclic aromatic hydrocarbons (PAHs) contamination. The use of certain phytochemicals and some polyphenolic compounds proved to be effective in blocking PAH-induced effects. The aim of the present study was to examine the possible inhibitory effects of ellagic acid (EA), present in berries and nuts, against B(a)P-mediated toxicity using in vitro and in vivo test systems. In vitro method included the Ames test, using Salmonella typhimurium tester strain TA100. In vivo experiments were based on mouse bone marrow micronucleus (MN) assay and immunoblotting. EA produced a decrease in the number of revertant colonies against B(a)P in the Ames assay. Further, there was a reduction in the mean number of micronucleated polychromatic erythrocytes in the presence of EA in the co-treatment protocol of the MN test. Western blotting results showed downregulation of CYP450 isoform CYP1A1 which prevented bioactivation of B(a)P. Thus, the present study demonstrates antimutagenic role played by EA against the mutagenic activity of B(a)P in both in vitro and in vivo systems.     

Heavy Metal Toxicity Responses of Two Willow (Salix) Varieties Grown Hydroponically: Development of a Tolerance Screening Test

The E.U. funded BIORENEW project is investigating bioremediation of industrially degraded land using biomass fuel crops, including willow. One of its goals is to develop a rapid screening test to assess the metal tolerance of large numbers of willow varieties. This should reflect how a plant will respond to heavy metals under various field conditions and in the long term. A preliminary experiment tested two varieties of contrasting ability to thrive in metal-contaminated soils. Trees were exposed to a metal cocktail in three different strengths of background solution. An appropriate strength solution (1/4 strength Hoaglands) was identified for differentiating variety performance, based on its effect on the biomass of plant fractions relative to control fractions. This is a response to heavy metals which can be quantified rapidly and simply. The relative performance of the varieties was comparable to their performance in field studies. This test will be used to assess the tolerance of further varieties.     

Sensitivity analysis of North American bird population estimates

The Partners in Flight North American Landbird Conservation Plan provided estimates of population sizes for 448 landbird species using a multiplicative model. Input parameters in this calculation included the area of state × Bird Conservation Region polygons, area-specific mean Breeding Bird Survey counts circa 1995, and adjustment factors for the distance over which species may presumably be correctly counted, the assumed pairing of singing males with non-singing females, and variability in the propensity of birds to sing over the course of the survey day. I assessed the sensitivity of this population calculation to changes in the input parameters. I assessed both local and global sensitivity of the model to changes in the parameters with Monte Carlo one-at-a-time simulations and the Fourier amplitude sensitivity test (FAST). Monte Carlo simulations were an estimate of local model sensitivity whereas FAST estimated global model sensitivity, accommodating the potential shared variance between model parameters. Monte Carlo simulations suggested population estimates were 39% more sensitive to changes in the detection distance adjustment than to the other parameters; the other parameters were nearly equal in their contribution to model sensitivity. Conversely, FAST analysis determined that each of the input variables aside from the pair adjustment provided roughly equal contributions to variability in population estimates. The most efficient means for improving continental population estimates for birds surveyed by the Breeding Bird Survey will be through increased scrutiny of the species-specific distance detection and time-of-day adjustments and improved understanding in the spatial and temporal variability in the mean Breeding Bird Survey count.     

Testing hypotheses on shape and distribution of ecological response curves

Niche theory with hypotheses on shape and distribution of ecological response curves is used in the studies of resource sharing of competing plant species. Predictions based on theory should be applicable when, e.g., effects of competing species on the ecological tolerances are assessed or species’ diversity along a resource gradient is evaluated. We studied the ecological response curves of competing plant species along a resource gradient in boreal forests. The study was based on nation-wide soil and vegetation data collected from 455 sample plots on boreal forests in Finland. Species response curves along a soil fertility gradient (in terms of C/N ratio) were estimated using generalized additive models. Distribution of species optima and the relationship of niche width and skewness to the location of the optimum were analyzed with new bootstrap tests. The developed tests can account for the effects of truncation observed in the response curves of several species and for the uneven distribution of observations on the gradient.The estimated response curves of the major field layer species of boreal forests were not evenly distributed along soil C/N gradient. The density of optima peaked with relatively high nitrogen availability. Species with optima at low nitrogen availability had relatively broad realized niches. Niche width was negatively correlated with the density of optima. Species optima were packed and niches were narrow at high resource levels. This result suggests that a greater number of more specialized species can occur and interspecific competition decreases niche widths at high resource levels. Species were packed in the gradient where the C/N ratio was lower than 25, i.e., in conditions where nitrification can take place. This indicates that the majority of the vascular plants of boreal forests are favoured by the availability of NO₃⁻. Those few species thriving at high C/N ratios have broader realized niches.     

复合人工湿地对有机污染物的去除效果初步研究

研究了由不同植物配置(驯化和未驯化)的两组下行和上行植物床组成的复合人工湿地对生活污水的净化效果。结果表明,CODCr和BOD5的去除率达67.3%,68.1%,总氮(TN)的去除率为26.9%,总磷(TP)的去除主要发生在上行床,去除率为81.6%。环芳烃(PAHs)中苊(Ace)、荧蒽(Flu)、芘(Py)、苯并[a]蒽(BaA)、屈(Chr)、苯并[b]荧蒽(BbF)、苯并[a]芘(BaP)、茚并[1,2,3-cd]芘(InP)和苯并[g,h,i](BPR)经下行床后,去除率超过80%,上行床去除较少。驯化床和未驯化床对PAHs的去除效果差异不显著。邻苯二甲酸酯(PAEs)中邻苯二甲酸二乙酯(DEP)和邻苯二甲酸二异丁酯(DiBP)经驯化床后,质量浓度显著升高,经未驯化床后邻苯二甲酸二(2-乙基)己酯(DEHP)含量显著降低。蚕豆根尖微核实验表明,不同植物配置对微核率影响差异并不显著,毒害物质经下行床后大部分被去除。     

鲤鱼对三种硝基芳族化合物的摄取、释放和生物富集

用第二松花江水和鱼体中多次检出的三种硝基芳族化合物来分别测定鲤鱼体中的生物富集系数（ＢＣＦ），摄取和释放动力学参数，以及在肌肉、肠、肝和鳃等组织中的分布。试验在半静态条件下进行。硝基芳族化合物在鲤鱼体内的释放可用双区一级动力学模型很好地描述。鲤鱼对２，４－二硝基甲苯和对硝基氯苯的富集过程中发现有未知的代谢产物生成。     

典型杀虫剂类内分泌干扰物对水生溞类的毒性效应研究进展

内分泌干扰物(endocrine disrupting chemicals,EDCs),尤其是具有内分泌干扰效应的杀虫剂,因能显著影响水生生物的生长发育和生殖系统,其潜在生态毒性效应引起了人们的广泛关注。溞类在水生生态系统食物链中起着重要的连接作用,更易受到水体中残留的杀虫剂类EDCs的影响,其毒性效应在水生生态系统毒理学研究中有着重要的意义。本文重点综述了杀虫剂类EDCs对溞类产生的生长发育毒性和生殖毒性,从酶活性变化角度分析由此产生的氧化应激和神经毒性,并在基因表达水平上揭示其毒性作用机制,发现杀虫剂类EDCs通过扰乱神经系统和内分泌系统发挥作用,并展望了杀虫剂EDCs在联合毒性、多代效应的研究前景,旨在为研究杀虫剂类EDCs对大型溞的毒性作用和生态环境风险评估提供依据。     

Does the African social spider Stegodyphus dumicola control the sex of individual offspring?

By scoring the chromosome number of developing embryos, we show that the sex ratio bias of the African social spider Stegodyphus dumicola Pocock is the result of an overproduction of female embryos. Only 17% of 585 embryos sexed from 14 egg sacs were male, a significant departure from a 1:1 sex ratio. We also explored the possibility of direct control of the sex of individual offspring in this species by examining the variance in the number of males per sac and the spatial distribution of male and female embryos within the sacs. We postulated that a variance in the number of males per sac lower than binomial (i.e., underdispersed or precise sex ratios) or a non-random distribution of male embryos within the sacs would suggest direct control of the sex of individual offspring. We found that the variance in the number of males per sac was indistinguishable from binomial and significantly larger than expected under exact ratios. Likewise, the spatial distribution of male embryos within three sacs examined was no more clustered than expected by chance. The sex ratio biasing mechanism in this species, therefore, apparently only allows control of the mean sex ratio but not of its variance. We present randomization and Monte Carlo methods that can be applied to test for departures from a random spatial arrangement of male and female embryos in an egg mass and for departures from binomial or exact ratios when not all members of a clutch have been sexed. Received: 21 October 1998 / Received in revised form: 23 March 1999 / Accepted: 26 April 1999     

旱地长期定位施肥对土壤剖面硝态氮分布与累积的影响

在 １５ ａ长期定位试验基础上研究了黄土高原旱地长期施用不同用量和配比的氮、磷肥对土壤剖面中硝态氮分布和累积的影响。结果表明：长期大量施用氮肥,在土壤剖面 １００～１８０ ｃｍ之间形成硝态氮累积层,峰值出现在 １４０ ｃｍ处,最大值为 ６７．９２ｍｇ／ｋｇ（单施 Ｎ １８０ ｋｇ／ｈｍ~２）; 配合施用磷肥可以降低土壤剖面硝态氮质量分数,根据试验,提出了旱地合理施肥的氮磷肥用量。     

‘A powerful alternative to Williams’ test with application to toxicological dose-response relationships of normally distributed data

The comparison of increasing doses of a treatment to a negative control is frequently part of toxicological studies. For normally distributed data Williams (1971, 1972) introduced a maximum likelihood test under total order restriction. But until now there seems to have been no solution for the arbitrary unbalanced case. According to the idea proposed by Robertson et al. (1988) we will apply in this article the basic concept of Williams on the class of multiple contrast tests for the general unbalanced parametric set-up. Simulation results for size and power and two examples for estimating the minimal toxic dose (MTD) are given.