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The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds. 相似文献
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Interspecies recombination In nature: a meningococcus that has acquired a gonococcal PIB porin 总被引:7,自引:0,他引:7
Julio A- Vázquez Sonsoles Berron Maria O'Rourke Gill Carpenter Edward Feil Noel H. Smith Brian G. Spratt 《Molecular microbiology》1995,15(6):1001-1007
A. vaginal isolate of Neisseria has been reported to resemble Neisseria meningitidis in biochemical characteristics but to react with serological reagents that are specific to the PI porin from Neisseria gonorrhoeae. We have confirmed that this isolate has the biochemical attributes of a meningococcus and have shown that it clusters among meningococcal Isolates on a dendrogram based on isoenzyme variation within housekeeping enzymes from populations of N. meningitidis and N. gonorrhoeae. Furthermore, the sequences of the fbp and adk genes were typical of those of N. meningitidis and were distinct from those of N. gonorrhoeae. However, the porB gene was very similar to the por genes of N. gonorrhoeae isolates that express the PIB class of outer-membrane porin (differing from one gonococcal por allele at only a single nucleotide site), and was clearly distinct from the porB genes of N. meningitidis. The isolate therefore appears to be a typical meningococcus, except that its porB gene has been replaced with the por gene from a gonococcus. 相似文献
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Active and passive cation transport and L antigen hertogeneity in low potassium sheep red cells 下载免费PDF全文
Several lines of experimental evidence are presented suggesting that the L antigens in low potassium (LK) sheep red cells are associated with separate Na(+)K(+) pump flux is distinct from the action of anti-L(l) on K(+) leak flux, implying that K(+) leak transport sites may not be converted into active pumps by the L antiserum. Treatment of LK red cells with trypsin completely abolished both the stimulation of K(+) pump flux and the enhancement of the rate of ouabain binding brought about by anti- L. That this effect is due to a total destruction of the L(p) determinant associated with the LK pump was evident from the complete failure of anti-L(p) to bind to trypsinized LK red cells. The L(p) antigen can be effectively protected against the trypsin attack by prior incubation with anti-L, indicating that the sites for antibody binding and trypsin action may be closely adjacent at the structural level. Trypsin treatment, however, did not interfere with anti-L(l) reducing ouabain insensitive K(+) leak influx, nor did it prevent binding of anti-L(ly), the hemolytically active L antibody which is probably identical with anti-L(l). The functional independence of the L(p) and L(l) sites was documented by the observation that anti-L(l) still reduced K(+) leak influx in LK cells with experimentally induced high potassium concentrations, at which K(+) pump flux is fully suppressed, whether or not anti-L(p) was binding to the L(p) antigen associated with the LK pump. 相似文献
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Industrial microbiology of solar salt production 总被引:3,自引:0,他引:3
Javor BJ 《Journal of industrial microbiology & biotechnology》2002,28(1):42-47
Solar salterns can be modeled as giant outdoor chemostats, much like a series of dams on a slow-moving river. Microorganisms
and their products play an essential, but sometimes uncharacterized, role in salt production in these ponds, from seawater
salinity up through NaCl saturation. They may physically affect the evaporation process and their by-products may chemically
modify or bind with dissolved ions. Many solar salt facilities engage microbiologists to establish monitoring programs for
analyses of nutrients, standing crop and associated biological variables in the ponds. Other solar salt companies engage microbiologists
only when there are “crises” in the ponds that interfere with salt production. Journal of Industrial Microbiology & Biotechnology (2002) 28, 42–47 DOI: 10.1038/sj/jim/7000173
Received 20 May 2001/ Accepted in revised form 13 June 2001 相似文献
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Several studies demonstrated that visual filtering mechanisms might underlie both conflict resolution of the Flanker conflict and the control of the Garner effect. However, it remains unclear whether the mechanisms involved in the processing of both effects depend on similar filter mechanisms, such that especially the Garner effect is able to modulate filtering needs in the Flanker conflict. In the present experiment twenty-four subjects participated in a combined Garner and Flanker task during two runs of functional magnetic resonance imaging (fMRI) recordings. Behavioral data showed a significant Flanker but no Garner effect. A run-wise analysis, however, revealed a Flanker effect in the Garner filtering condition in the first experimental run, while we found a Flanker effect in the Garner baseline condition in the second experimental run. The fMRI data revealed a fronto-parietal network involved in the processing of both types of effects. Flanker interference was associated with activity in the inferior frontal gyrus, the anterior cingulate cortex, the precuneus as well as the inferior (IPL) and superior parietal lobule (SPL). Garner interference was associated with activation in middle frontal and middle temporal gyrus, the lingual gyrus as well as the IPL and SPL. Interaction analyses between the Garner and the Flanker effect additionally revealed differences between the two experimental runs. In the first experimental run, activity specifically related to the interaction of effects was found in frontal and parietal regions, while in the second run we found activity in the hippocampus, the parahippocampal cortex and the basal ganglia. This shift in activity for the interaction effects might be associated with a task-related learning process to control filtering demands. Especially perceptual learning mechanisms might play a crucial role in the present Flanker and Garner task design and, therefore, increased performance in the second experimental run could be the reason for the lack of behavioral Garner interference on the level of the whole experiment. 相似文献
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ANDREAS LUEK GEORGE E. MORGAN BJÖRN WISSEL JOHN M. GUNN CHARLES W. RAMCHARAN 《Freshwater Biology》2010,55(8):1616-1627
1. Yellow perch (Perca flavescens) are often the only surviving fish species in acidified lakes. We studied four lakes along a gradient of recovery from acidification and that had different food web complexities. All had abundant yellow perch, two had low piscivore abundance, one had a well‐established piscivore population and one was manipulated by introducing piscivorous smallmouth bass (Micropterus dolomieu). We hypothesised that there would be strong effects on perch abundance, behaviour and diet induced by the presence of piscivores. 2. In the manipulated lake, the bass reduced yellow perch abundance by 75% over a 2‐year period. Concomitantly, perch use of the pelagic habitat fell from 48 to 40%. 3. In contrast to findings from less disturbed systems, yellow perch in the littoral zone of the manipulated lake did not strongly shift from zooplankton to benthic food sources after the arrival of piscivores. Diet analysis using stable carbon isotopes revealed a strong continued reliance on zooplankton in all lakes, independent of the degree of piscivory. The failure to switch to benthos in the refuge area of the littoral zone is most likely related to the depauperate benthos communities in these formerly acidified lakes. 4. Yellow perch in lakes recovering from acidification face a considerable ecological challenge as the necessary switch to benthic diet is hindered by a low abundance of benthos. The arrival of piscivores in these recovering lakes imposes further restrictions on perch access to food items. We infer that future recovery of perch populations (and higher trophic levels) will have to be preceded by the re‐establishment of diverse benthic macroinvertebrate communities in these lakes. 相似文献
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JON E. SWENSON BJØRN DAHLE HELENA BUSK OLE OPSETH THOMAS JOHANSEN ARNE SÖDERBERG KJELL WALLIN GORAN CEDERLUND 《The Journal of wildlife management》2007,71(6):1993-1997
Abstract: In North America, brown bears (Ursus arctos) can be a significant predator on moose (Alces alces) calves. Our study in Sweden is the first in which brown bears are the only predator on moose calves. Bears and moose occurred at densities of about 30/1,000 km2 and 920/1,000 km2, respectively, and bears killed about 26% of the calves. Ninety-two percent of the predation took place when calves were <1 month old. Bear predation was probably additive to other natural mortality, which was about 10% in areas both with and without bears. Females that lost their calves in spring produced more calves the following year (1.54 calves/F) than females that kept their calves (1.11 calves/F), which reduced the net loss of calves due to predation to about 22%. 相似文献
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