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91.
The concentrations of monoamines in the hypothalamus were determined in yellow perch Perca flavescens before and after injection with lipopolysaccharide (LPS; 3 mg kg−1 fish weight) or saline to test for the presence of neurochemical changes potentially associated with changes in plasma cortisol characteristic of intraperitoneal (ip) challenge with LPS. In the first experiment, yellow perch were injected with saline or LPS and the hypothalamus removed and plasma sampled before and at 0.5, 1.5, 3.0, and 6 h after injection. Plasma cortisol was elevated in both saline- and LPS-injected fish through 1.5 h after injection and returned to levels resembling pre-injection by 3 h after injection. Significantly higher amounts of cortisol in plasma from LPS-injected relative to saline-injected fish were observed 6 h following injection. A significant decrease relative to levels observed 0.5–3 h after handling was observed in serotonin concentrations at 6 h following LPS and saline injection with a concomitant increase in the ratio of 5-hydroxyindoleacetic acid:serotonin. In the second experiment, hypothalamic monoamines were sampled before and at 3, 6, 9, 12, and 24 h after injection with LPS or saline. Significant increases from pre-injection levels were observed in the ratio 5-hydroxyindoleacetic acid:serotonin at 9, 12, and 24 h after injection, but no differences were detected between LPS- and saline-injected fish. These results support a model linking serotonergic system activation following handling stress, but no correlations with the sustained elevations of plasma cortisol associated with inflammatory challenge were observed.  相似文献   
92.
The temporal variation in macrobenthos abundance was studied in Funka Bay in the periods 2001–2004 and 2007–2010. Dissolved oxygen just above the sea floor of the basin was lower and ignition loss at the level of the sea floor was higher in 2007–2010 than in 2001–2004. Macrobenthic species were categorized into three groups: long-lived species, sedental polychaeta Notomastus latericeus, and short-lived species. Ignition loss was the most influential factor affecting macrobenthos abundance as this variable restricts the recruitment of macrobenthos. The abundance of both long-lived species and N. latericeus was lower between 2007 and 2010 than between 2001 and 2004. Supplementation of oxygen from outside the bay by the Tsugaru Warm Current may be an important factor impacting the increase in the abundance of long-lived species. The abundance of N. latericeus barely increased between 2007 and 2010, possibly because dissolved organic matter, which is their food item, may have become limited due to a narrow chink between sediments with eutrophication. The abundances of short-lived species did not differ between the periods 2001–2004 and 2007–2010 due to the organisms having a low tolerance to hypoxia. The current conditions in Funka Bay are on the verge of turning the bay into an azoic zone.  相似文献   
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Phenolics from root exudates or decaying residues are usually referred as autotoxins of several plant species. However, how phenolics affect soil microbial communities and their functional significances are poorly understood. Rhizosphere bacterial and fungal communities from cucumber (Cucumis sativus L.) seedlings treated with p-coumaric acid, an autotoxin of cucumber, were analyzed by high-throughput sequencing of 16S rRNA gene and internal transcribed spacer amplicons. Then, feedback effects of the rhizosphere biota on cucumber seedlings were evaluated by inoculating non-sterilized and sterilized rhizosphere soils to sterilized background soils. p-Coumaric acid decreased the bacterial diversity of rhizosphere but increased fungal diversity and altered the compositions of both the bacterial and fungal communities. p-Coumaric acid increased the relative abundances of microbial taxa with phenol-degrading capability (such as Chaetomium, Humicola, and Mortierella spp.) and microbial taxa which contained plant pathogens (such as Fusarium spp.). However, p-coumaric acid inhibited the relative abundances of Lysobacter, Haliangium, and Gymnoascus spp., whose species can have pathogen-antagonistic and/or plant-growth-promoting effects. The positive effect of cucumber rhizosphere microbiota on cucumber seedling growth was reduced by p-coumaric acid. Overall, our results showed that, besides its direct phytotoxicity, p-coumaric acid can inhibit cucumber seedling growth through generating negative plant-soil microbial interactions.  相似文献   
95.
An experiment was conducted with tobacco (Nicotiana tabacum L.) grown in a Cd- and Pb-contaminated calcareous soil amended with 0.0, 1.0, 2.5, and 5.0% (w/w) tobacco stalk biochar (BC). The BC amendment significantly increased organic matter, total C, N, P, and K contents of soil, and the C/N ratio. Bioavailable metal concentrations (DTPA extraction) decreased by increasing BC application rate. The 5.0% BC amendment significantly decreased the DTPA-extractable Cd and Pb by 10.4 and 13.6%, respectively. Correspondingly, the bioaccumulation and translocation factors of Cd and Pb also decreased by increasing the BC addition rates and this indicated that BC inhibited the uptake and transfer of both Cd and Pb by tobacco plants. Moreover, high-throughput sequencing revealed that BC increased Chao1 richness, Shannon’s diversity and Simpson’s diversity of bacterial communities of soil. The relative abundance and genera composition of Adhaeribacter, Rhodoplanes, Pseudoxanthomonas, and Candidatus Xiphinematobacter increased under BC treatments, while those of Kaistobacter, Lacibacter, and Pirellula decreased. Overall, BC increased soil nutrients (C, N, P, and K contents), enhanced bacterial diversity indexes and richness, and changed the bacterial community composition, which may all have contributed to reduce the mobility and bioavailability of both Cd and Pb in a calcareous soil.  相似文献   
96.
97.
Goal, Scope and Background   In a preliminary ecological risk assessment, potential adverse effects of contaminants are often evaluated by measuring chemical residues and comparing these with regulatory guidelines. However limitations with this approach with regards to establishing actual effects have resulted in the increasing usage of sublethal effects-based assays, including biomarkers, to evaluate the hazard posed by contaminants in the environment. In this study a number of effects-based endpoints in the earthworm Aporrectodea caliginosa were evaluated to determine their comparative sensitivity for assessment of adverse effects of soil contaminated with petroleum hydrocarbons. Methods   Adult and juvenile earthworms were exposed for 4 weeks to sublethal concentrations of soil collected before and after remediation of a petroleum-contaminated site. A suite of endpoints were measured in these earthworms, including mortality, fecundity, growth, and juvenile maturation, and two less traditional endpoints, the biomarker, the neutral red retention assay (NRRA) and an avoidance behaviour test. Results and Discussion   Cocoon viability in this species is not a reliable parameter to measure, due to low viability in controls and a high coefficient of variation. Growth in adult earthworms was a more sensitive parameter than cocoon production. Maturation and growth of juveniles have been proposed as more sensitive endpoints than adult cocoon production and growth respectively. This was not apparent in the growth parameters, but maturation of juveniles did appear to be more sensitive than cocoon production by adults. The NRRA was a more sensitive parameter than cocoon production, and the NRRA and growth were both affected at the lowest concentration tested. The NRRA response appeared to be more sensitive than growth, but NRRT was only evaluated in one soil only, while the other parameters were assessed in two soils. However, the NRRA has previously been found to be more sensitive than growth after exposure to a number of contaminants. The avoidance behaviour assay exhibited similar sensitivity to growth and fecundity and could therefore be useful as a simple pre-screening test. Conclusion   The chronic endpoints, growth, cocoon production, and juvenile maturation parameters, were all sensitive endpoints for detecting exposure to the petroleum-hydrocarbon-contaminated soil. The NRRA was the most sensitive of the endpoints assessed and could be used as an early-warning indicator to predict adverse impacts. Avoidance behaviour could be used as a simple pre-screening test to evaluate contaminated soils prior to more extensive and invasive testing. Recommendations and Perspective   Measuring chemical concentrations in environmental samples is not always useful, as the toxicological impacts of exposure to these concentrations are not always discernible. However, the use of effects-based endpoints, either in situ or in the laboratory using laboratory-reared earthworms, can account for the bioavailability of chemicals in the soil, and can therefore provide information on the toxicological impacts of exposure. The assays tested in this research were sensitive indicators of exposure, and therefore can be used to determine potential ecological risks at contaminated sites and to monitor the progress of remediation at these sites.  相似文献   
98.
Understanding the relationship between an index of biological community state and habitat is important for policy makers and environmental managers. A common approach to modeling this relationship is to use regression. However, this simple method becomes complicated when the data are clustered and have both within-cluster and between-cluster spatial correlation. This article proposes a Bayesian hierarchical model that incorporates both types of spatial correlation. This model yields both an understanding of the within-cluster relationships as well as an overall relationship between these variables. We apply this method to evaluate the relationship between the index of biotic integrity (a common measure of fish condition) and the qualitative habitat evaluation index (a common measure of habitat quality). This method allows us to show that there is a relationship between the biological community state and habitat and that this relationship varies across river basins, while accounting for the within- and between-spatial correlations.  相似文献   
99.
基于多年MODIS NDVI 分级的河北平原农田生产力评价   总被引:2,自引:0,他引:2  
根据中等分辨率航天成像光谱仪(MODIS)遥感数据计算的归一化植被指数(NDVI)被广泛用于作物长势监测和产量预报, 但由于NDVI 数值在不同年份的同一时期变化较大, 直接用于评价农田生产力会有较大误差。本文以河北平原所在的北纬37°~39°之间连续种植的冬小麦农田为研究区域, 通过对多年冬小麦MODISNDVI 数据进行比较和分级, 尝试用每季NDVI 在区域内的高低级别评估区域农田生产力。Landsat 卫星数据用于对不同时相MODIS 图像进行精确配准, 从而实现像素尺度上长时间序列数据的统计分析。首先, 对区域内2000~2008 年间每年作物返青期到成熟期的NDVI 平均值及各生育阶段NDVI 平均值分别进行高低分级, 以了解河北平原农田生产力的空间变异, 结果显示其中高水平农田分布在太行山山前平原, 指数等级水平并没有完全按南北走向趋势分布, 表明该研究方法受纬度差异的影响较小。不同年份分析结果显示, 2008 年东部地区也出现了较高等级的田块。其次, 利用NDVI 分级结果计算出9 年间NDVI 等级的变异系数, 对采用不同生育期NDVI 可能带来的误差进行了分析, 结果显示不同小麦生育期NDVI 等级的变异系数不同, 返青期和成熟期变异系数较大, 且具有一定的地理差异。最后, 利用GIS 空间分析方法以9 年NDVI 分级结果为基础制作了以县为单元的麦田生产力等级图, 结果显示河北平原农田生产力高低分区, 同时也表明中低水平区块有较大提升空间, 为河北县级土地管理和耕地质量管理提供理论依据。  相似文献   
100.
The aim of this article is to study the geographical distribution and historical patterns of use of a little known root crop native to Europe—marsh woundwort Stachys palustris L. The species grows in wet grasslands and arable fields. It produces edible tubers. Both ethnographic literature and archival sources were searched. Seventeen reliable references concerning the consumption of S. palustris in southern and south–eastern Poland were found. The tubers were usually dried and powdered, and then added to soups or to bread dough. They were also eaten as raw snacks. The plant was used mainly during food shortages in spring, until the turn of the nineteenth and twentieth century, and later only as an occasional raw snack until the 1970s. Marsh woundwort was also eaten in western Ukraine (one reference). There are many references to the edibility of marsh woundwort in the eighteenth and nineteenth century European economic botany literature, particularly in Sweden and Great Britain. These publications tried to popularize the use of S. palustris as food. However, there is no firm evidence from these countries that marsh woundwort was used as food there. Marsh woundwort was also used, throughout northern and central Europe, as pig fodder and as a medicinal plant, particularly for healing wounds. Further studies on the nutritive value of this forgotten crop should be undertaken, particularly that there is little knowledge of the chemical composition of both marsh woundwort and its Asian relative Stachys affinis widely cultivated in China as a vegetable.  相似文献   
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