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111.
Allogeneic assays were conducted in situ on the Red Sea hydrocoral Millepora dichotoma. Forty-five pairwise combinations among ten colonies and ten control isografts were set up in four replicates each (180 and 40 pairs, respectively) and followed for up to 8 mo in the Gulf of Eilat, Red Sea in 1992–1993. In 42 allogeneic combinations we recorded a reproducible and unilateral tissue and skeleton overgrowth which developed within the first 10 wk up to 20 mm. Following the development of these primary overgrowths, four types of secondary responses were observed among most incompatible combinations: reversals in overgrowth directionality, tissue necroses, stand-offs and abnormal growth patterns. Secondary responses within a given set of replicates of most allogeneic combinations were characterized by high variability in type and intensity of response. Based on the outcomes of primary overgrowths, a complex nontransitive hierarchy was constructed for the ten colonies. All isografts and three allogeneic combinations fused within 3 wk. Fusion pattern between the three allogeneic combinations was nontransitive: one M. dichotoma colony repeatedly fused with two other colonies (four assays each). However, these two colonies not only did not fuse with each other, but one of them repeatedly overgrew its confrére. In the third compatible combination, the most superior and the most inferior colonies in the network of hierarchies among the ten colonies, fused in all tested assays. These results are compared with allogeneic outcomes in other enidarians, where nontransitive fusion between allogenic colonies have never been recorded. 相似文献
112.
Malte Andersson Frank Götmark Christer G. Wiklund 《Behavioral ecology and sociobiology》1981,9(3):199-202
Summary The information-centre hypothesis suggests that bird colonies function as sources of information about good feeding sites, to which unsuccessful birds may follow foragers. One assumption of the hypothesis is that unusually successful foragers are followed by other colony members when returning to a newly found, rich food source. We tested this assumption in a colony of Black-headed Gulls (Larus ridibundus). Parents feeding their young from a rich, artificial food source were observed on their return trips to the feeding site. In none of 50 cases did other colony members follow them to the newly found food. However, the gulls were attracted to groups of foraging conspecifics. In experiments with paired food piles and a group of model gulls at one pile in each pair, Black-headed Gulls always alighted first at the piles with models. Hence the information-centre mechanism was refuted, but the gulls did acquire food information from each other in another way. 相似文献
113.
成百上千的活性物质正被用于人药和兽药处方中.由于药物的广泛应用,它们的残留物可通过多种途径进入环境.虽然主要通过尿和粪便的排泄,但是药品生产中的排放也应被考虑.当抗生素用于水产业,就会产生更直接的影响.污水处理设备不能完全除去药物,因此药物会出现在地表和地下水样品中.近年来,人们对环境中药物的兴趣正在增加,需要建立一种快速、灵敏、有选择性的方法来分析水样. 相似文献
114.
Palaeobiological evidence indicates that gymnosperms were wind-pollinated and that insect pollination began in angiosperms in the Lower Cretaceous (ca. 135 mya) leading to close associations between higher plants and their pollinators. Cycads, which were widespread and pervasive throughout the Mesozoic (250-65 mya) are among the most primitive living seed-plants found today. Because pollination by beetles and by thrips has now been detected in several modern cycads, it is attractive to speculate that some insects and cycads had already developed similar mutualistic interactions in the Triassic (250-205 mya), long before the advent of angiosperms. We also draw attention to another key factor in this insect-plant relationship, namely secondary, defensive plant substances which must always have controlled interspecific interactions. Cycads mainly produce toxic azoglucosides and neurotoxic non-protein amino acids (e.g. BMAA), which apparently are crucial elements in the development and maintenance of mutualism (pollination) and parasitism (herbivory) by cycad-linked herbivores. We now add new results on the uptake and storage of the main toxin, cycasin, of the Mexican cycad Zamia furfuracea by its pollinator, the weevil Rhopalotria mollis, and by a specialist herbivore of Zamia integrifolia, the aposematic Atala butterfly Eumaeus atala. 相似文献
115.
116.
Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) were found in annually laminated sediments from Lakes Zurich, Baldegg, and Lugano in Switzerland. Octachlorodibenzo-p-diox in (OCDD) predominated, averaging approximately 1.3 ppb. The congener distribution indicated that combustion was the source of PCDD and PCDF in these sediments. In these dated sediment cores, we found that PCDD and PCDF were absent from the sediments before about 1945, but increased thereafter. 相似文献
117.
118.
In order to investigate topsoils as potential sinks for chlorinated solvents from the atmosphere, the degradation of trichloromethane (CHCl(3)), 1,1,1-trichloroethane (CH(3)CCl(3)), tetrachloromethane (CCl(4)), trichloroethene (C(2)HCl(3)) and tetrachloroethene (C(2)Cl(4)) was studied in anoxic laboratory experiments designed to simulate denitrifying conditions in water unsaturated topsoil. Active denitrification was demonstrated by measuring the release of 15N in N(2) to the headspace from added 15N labeled nitrate. The degradation of chlorinated aliphatic compounds was followed by measuring their concentrations in the headspace above the soil.The headspace concentrations of all the chlorinated solvents except CH(3)CCl(3) were significantly (P相似文献
119.
Schröder FR Schulze C Matthies M 《Environmental science and pollution research international》2002,9(2):130-135
The GREAT-ER software was used to calculate linear alkylbenzene sulphonate [LAS] and boron concentrations in the Itter stream in North Rhine-Westfalia, Germany. The aim was to investigate the predictive strength of this newly developed tool and to compare its results to measured data. Substance-specific input data which were used in this scenario were partly generic (e.g. LAS and sodium perborate tetrahydrate consumption figures for Germany) and partly (site-)specific data (e.g. half-life time for LAS elimination). The comparison with the measured data reveals that the model predictions for LAS and boron are correct at least within a factor of two, only if generic German consumption data is applied. By using refined input data, the accuracy can be increased further. 相似文献
120.
Barbro M. Gullvåg Hartmut Frank Yrjü Norokorpi 《Environmental science and pollution research international》1996,3(3):159-162
The study has been performed in a supposedly clean-air region of a Northern Finnish forest with a homogeneous stand of Scots pine. Stomatal epicuticular wax layer erosion is described using a classification system of five erosion stages. The percentage of stomatal wax within each erosion stage is calculated and the results are treated statistically, which makes the morphological study of the needle surface semi-quantitative. Severe wax degradation has already been found in the current year, increasing with the age of the needles. In this area, the wax layer erosion is correlated with secondary air pollutants, as analyses have shown high trichloroacetate (TCA) levels in needles from the same trees. The wax layer analyses are in accordance with earlier findings which have demonstrated differences in tolerance to TCA. 相似文献