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1.
2.
Bioturbation by benthic infauna has important implications for the fate of contaminants as well as for changes to the sediment
structure, chemistry and transport characteristics. There is an extensive literature dealing with the influence of sedimentary
variables on the structure and function of infaunal marine and estuarine organisms but less is known of the converse, the
influence of biota on sedimentary structure. Although some work has been carried out regarding spatial and temporal patterns
of bioturbation, little attention has been given to the effects of pollution. The paper gives a framework of animal sediment
relationships in an intertidal environment and discusses the general role of macrofauna in structuring and modifying sedimentary
features. A brief outline of the various techniques used for quantifying the degree of bioturbation is given and some of these
techniques have then been used to demonstrate the effect of a petrochemical discharge on the bioturbation potential of intertidal
communities in the Humber estuary, eastern England. These studies indicate an increase in bioturbation with increasing distance
from the source of pollution, not only because of differences in abundance, animal size and depth of activity but also because
of the difference in species composition between the communities. As a means of interpreting the responses, the species present
have been broadly classified in terms of their feeding strategy and sediment modification potential. The paper concludes by
discussing the potential impact, in terms of effect on sediment transport, of selectively removing the different guilds (by
pollution).
Received: 8 February 1999 / Received in revised form: 10 May 1999 / Accepted: 14 May 1999 相似文献
3.
4.
Eileen M. Proctor Judith L. Isaac-Renton William B. Robertson William A. Black 《CMAJ》1985,133(9):876-878
A survey was done of Canadians who had been interned by the Japanese during World War II to assess the prevalence of latent infection with Strongyloides stercoralis in this group. Packages containing three mail-in kits and a questionnaire were sent to 992 men, 694 (70%) of whom responded. Larvae were found in the stool specimens of four of the respondents. Examination of stool specimens after formalin-ether concentration was the most successful method of detecting Strongyloides larvae. The Baermann concentration technique yielded negative results in all four men. Three of the four cases of strongyloidiasis were detected after sampling of three fecal specimens. In the fourth case additional specimens were requested on the basis of data derived from the questionnaire. The most frequently cited clinical manifestations were abdominal pain, weight loss, diarrhea and rashes. 相似文献
5.
Lina Long Douglas R. McCabe M. Eileen Dolan 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1999,731(2):128
A highly sensitive and selective method for determining 8-oxoguanine in plasma and urine was developed by high-performance liquid chromatography with electrochemical detection. The compound was separated by gradient elution on a C18 reversed-phase column with a mobile phase of acetonitrile and 0.1 M sodium acetate, pH 5.2. 8-Hydroxy-2′-deoxyguanosine was used as internal standard. 8-Oxoguanine was detected electrochemically by setting the potential to +300 mV vs. Pd reference. The sensitivity of the assay was 22 ng/ml with a signal-to-noise ratio of 7:1. The within-day relative standard deviations for 8-oxoguanine quality control samples with concentrations of 3340, 1340 and 84 ng/ml were 3.6, 4.3 and 5.7% for plasma, and 4.1, 4.6 and 6.2% for urine, respectively. The day-to-day relative standard deviations for the same samples were 3.8, 6.8 and 7.1% for plasma, and 3.9, 7.0 and 7.9% for urine, respectively. The method is designed to study the pharmacokinetics and metabolic fate of O6-benzylguanine in a phase I clinical trial. Previously, O6-benzyl-8-oxoguanine was identified as the primary metabolite of O6-benzylguanine in humans. We now demonstrate that 8-oxoguanine is a further metabolite of O6-benzylguanine. 相似文献
6.
7.
Elliott C. Kulakowski Joseph Maturo Stephen W. Schaffer 《Archives of biochemistry and biophysics》1981,210(1):204-209
Cardiac sarcolemma preparations of both pig and rat ventricles were found to possess two sets of taurine-binding components. The two proteins from pig heart were solubilized with the detergent Ammonyx-Lo. Characterization of these solubilized proteins revealed that both components are glycoproteins and retain the binding properties observed for the membrane isolate. However, the characterization also revealed several differences between the proteins including their binding specificities, their affinities for taurine, their binding isotherms, and their molecular sizes. Possible functions of these two taurine-binding proteins are discussed. 相似文献
8.
D. C. Coleman R. V. Anderson C. V. Cole E. T. Elliott L. Woods M. K. Campion 《Microbial ecology》1977,4(4):373-380
Flows of biomass and respiratory carbon were studied in a series of propylene-oxide sterilized soil microcosms. One-half of the microcosms received three pulsed additions of 200 ppm glucose-carbon to mimic rhizosphere carbon inputs. Biotic variables were: bacteria (Pseudomonas) alone, or amoebae (Acanthamoeba) and nematodes (Mesodiplogaster) singly, or both combined in the presence of bacteria.Over the 24-day experiment, respiration was significantly higher in the microcosms containing the bacterial grazers. Biomass accumulation by amoebae was significantly higher than that by nematodes. The nematodes respired up to 30-fold more CO2 per unit biomass than did amoebae. Similar amounts of carbon flowed into both respiratory and biomass carbon in microcosms with fauna, compared with the bacteria-alone microcosms. However, partitioning of available carbon by the microfauna varied considerably, with little biomass production and relatively more CO2-C produced in the nematode-containing microcosms. The amoebae, in contrast, allocated more carbon to tissue production (about 40% assimilation efficiency) and correspondingly less to CO2. 相似文献
9.
10.
Cytokinetic basis for the impaired activation of lymphocytes from patients with primary intracranial tumors 总被引:4,自引:0,他引:4
L H Elliott W H Brooks T L Roszman 《Journal of immunology (Baltimore, Md. : 1950)》1984,132(3):1208-1215
Patients with malignant brain tumors have a variety of immunologic abnormalities, including the impaired responsiveness of peripheral blood lymphocytes (PBL) to mitogens and alloantigens. We further investigated this impairment of lymphocyte reactivity by employing the techniques of limiting dilution analysis and cytokinetic analysis. PBL preparations from patients have approximately six times fewer phytohemagglutinin (PHA)-responsive cells than PBL from normal subjects. Similar results were obtained with purified T cell preparations. Cytokinetic analysis of PHA-induced [3H]thymidine incorporation employing colchicine blocking of mitosis demonstrated that the number of first generation cells entering the S-phase of mitosis for each 24-hr period was less for PBL from patients than for PBL from normal individuals. First generation responding cells from patients and normal subjects entered DNA synthesis at the same time (48 to 72 hr). Cytokinetic analysis over a period of 168 hr demonstrated that whereas PBL from normal individuals demonstrated second generation responding cells, PBL from the majority of patients did not, thus indicating a defect in their ability to undergo clonal expansion. Measurement of interleukin 2 (IL 2) activity in culture fluids from PHA-activated PBL from normal subjects and patients revealed significantly lower IL 2 levels in culture fluids from PBL from patients. The addition of various concentrations of lectin-free IL 2 to PBL from patients stimulated with PHA did not restore responsiveness to normal values. There was no difference between the levels of interleukin 1 (IL 1) produced by lipopolysaccharide-activated monocytes from normal subjects and patients. Overall, these results suggest that an intrinsic defect exists in T cells obtained from brain tumor patients that renders them unable to enter into normal mitogen-induced blastogenesis. 相似文献