Summary The use of reticulated polyurethane foam as a support material for the immobilization of methanogenic associations and its application to the anaerobic treatment of fine particulate solid wastes was investigated. The colonization of polyurethane support particles in a continuous upflow reactor fed on a mixture of acetate, propionate and butyrate, was both rapid and dense. The combination of rumen microorganisms and colonized support particles in a two-phase digester resulted in an efficient anaerobic decomposition of papermill sludge. 相似文献
Human metapneumovirus (hMPV) is a recently discovered respiratory virus associated with bronchiolitis, pneumonia, croup and exacerbations of asthma. Since respiratory viruses are frequently detected in patients with acute exacerbations of COPD (AE-COPD) it was our aim to investigate the frequency of hMPV detection in a prospective cohort of hospitalized patients with AE-COPD compared to patients with stable COPD and to smokers without by means of quantitative real-time RT-PCR.
Results
We analysed nasal lavage and induced sputum of 130 patients with AE-COPD, 65 patients with stable COPD and 34 smokers without COPD. HMPV was detected in 3/130 (2.3%) AE-COPD patients with a mean of 6.5 × 105 viral copies/ml in nasal lavage and 1.88 × 105 viral copies/ml in induced sputum. It was not found in patients with stable COPD or smokers without COPD.
Conclusion
HMPV is only found in a very small number of patients with AE-COPD. However it should be considered as a further possible viral trigger of AE-COPD because asymptomatic carriage is unlikely. 相似文献
Cordylophora caspia is a hydrozoan which causes biofouling in power plants and is an increasing problem in UK drinking water treatment works. Thermal control is not usually feasible without a ready source of hot water so laboratory experiments were conducted to assess whether using pulsed doses of chlorine is an alternative solution. C. caspia polyps disintegrated after a single 20?min dose (the length of one backwash cycle in water treatment work filter beds) of 2.5?ppm chlorine. Without further treatment colonies regenerated within 3 days, but repeated dosing with chlorine for 20?min each day inhibited this regeneration. The resistance of surviving colonies to chlorine increased over time, although colony size and polyp regeneration continued to fall. These results suggest pulsed treatment with chlorinated backwashes at 2?ppm could be used to control C. caspia biofouling in rapid gravity filters and this may have relevance to other settings where thermal control is not feasible. 相似文献
Male hamsters are very dependent on chemosensory cues for normal mating
behavior. We have previously reported that central, vomeronasal pathways
are intensely and selectively activated during mating or pheromonal
stimulation. The contribution of main olfactory sensory input to the
patterns of c-fos activation was investigated in this study. Sexually
inexperienced male hamsters were either made anosmic by intranasal infusion
of zinc sulfate or remained intact. Fos protein immunoreactivity was
analyzed in main olfactory and vomeronasal pathways of the zinc
sulfate-treated, anosmic animals after mating with receptive females for 45
min, and compared with Fos patterns seen in intact mating animals, some of
which have been described in a previous publication. The zinc
sulfate-treated anosmic males described here all mated when given access to
receptive females. Whether mated or unstimulated, anosmic males had little
or no Fos expression in main olfactory pathways; significantly less even
than in unstimulated intact animals. Mating did not increase Fos expression
in main olfactory pathways of intact animals over that of unstimulated
intact controls. However, Fos expression in central vomeronasal pathways
was significantly higher in mating anosmic males, as in intact males,
compared with appropriate non-mating controls. Fos expression was
significantly different between intact and zinc sulfate-treated anosmic
mating males in only one area studied. The rostral anterior medial
amygdala, known to receive a small olfactory terminal field, had
significantly lower Fos expression in zinc sulfate-treated anosmic males
that mated when compared with intact-mating animals. Thus, functional main
olfactory input to the rostral vomeronasal amygdala can be demonstrated but
does not appear to be critical for mating behavior in previously
inexperienced male hamsters with intact vomeronasal organs. Other main
olfactory input appears to have a negligible contribution to Fos-patterns
in such animals.
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Intermediate filaments have been isolated from rabbit intradural spinal nerve roots by the axonal flotation method. This method was modified to avoid exposure of axons to low ionic strength medium. The purified filaments are morphologically 75-80 percent pure. The gel electrophoretogram shows four major bands migrating at 200,000, 145,000, 68,000, and 60,000 daltons, respectively. A similar preparation from rabbit brain shows four major polypeptides with mol wt of 200,000 145,000, 68,000, and 51,000 daltons. These results indicate that the neurofilament is composed of a triplet of polypepetides with mol wt of 200,000, 145,000, and 68,000 daltons. The 51,000-dalton band that appears in brain filament preparations as the major polypeptide seems to be of glial origin. The significance of the 60,000- dalton band in the nerve root filament preparation is unclear at this time. Antibodies raised against two of the triplet proteins isolated from calf brain localize by immunofluorescence to neurons in central and peripheral nerve. On the other hand, an antibody to the 51,000-dalton polypeptide gives only glial staining in the brain, and very weak peripheral nerve staining. Prolonged exposure of axons to low ionic strength medium solubilizes almost all of the triplet polypeptides, leaving behind only the 51,000- dalton component. This would indicate that the neurofilament is soluble at low ionic strength, whereas the glial filament is not. These results indicate that neurofilaments and glial filaments are composed of different polypeptides and have different solubility characteristics. 相似文献
Many lowland floodplain habitats have been disconnected from their rivers by flood defence banks. Removing or lowering these banks can reinstate regular flooding and thus restore these important wetland plant communities. In this study we analyse changes in wetland hydrology and plant community composition following the lowering of flood defence banks at a floodplain of the River Don in the United Kingdom (UK). The aim of the restoration project was to improve the quality of “floodplain grazing marsh” habitat, which is a group of wetland communities that are of conservation interest in the UK. We analyse changes in species richness and community composition over a period of 6 years, and compare the presence of indicator species from the target floodplain grazing marsh plant communities. The lowering of the flood banks increased the frequency of flood events, from an estimated average of 1.7 floods per year to 571 floods per year. The increased flooding significantly increased the proportion of time that the wetland was submerged, and the heterogeneity in hydrological conditions within the floodplain. There were significant differences in composition between the pre-restoration and restored plant communities. Plants with traits for moisture tolerance became more abundant, although the communities did not contain significantly more ‘target’ floodplain grazing marsh species at the end of the study period than prior to restoration. Colonisation by floodplain grazing marsh species may have been limited because environmental conditions were not yet suitable, or because of a shortage of colonising propagules. While the desired target plant community has not been achieved after 5 years, it is encouraging that the community has changed dynamically as a result of hydrological changes, and that moisture-tolerant species have increased in occurrence. Over the next few decades, the restored flood regime may cause further environmental change or colonisation events, thus helping increase the occurrence of desired floodplain grazing marsh indicator species.
Drosophila mercatorum is a species that can give rise to totally homozygous
parthenogenetic strains. Using the technique of DNA-DNA hybridization, we
have assessed the overall single-copy DNA differences among three
independently derived strains that represent three independent genomes.
Among strains, the average difference between homoduplex and heteroduplex
median melting temperatures is 1.3 degrees C. This represents greater than
or equal to 1.3% base-pair mismatch. Normalized percent of reassociation
indicates further genetic differences, probably reflecting
insertion/deletion differences and/or regions of the genome that are highly
variable. This overall intraspecific genetic variation is higher than
generally is thought to exist but is consistent with growing evidence of
extensive DNA diversity within species of invertebrates. High intraspecific
DNA variation may be correlated with rapid phyletic rates of evolution.
Because of this high level of variation, the technique of DNA-DNA
hybridization may be used to study intraspecific variation in invertebrates
but is limited in its usefulness for higher systematic studies.
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