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1.
Sacramento Doralice Rodrigues Coelho Rosalie Reed Rodrigues Wigg Márcia Dutra Toledo Luna Linhares Luiz Fernando de Matos dos Santos Marta Gonçalves Azevedo Soares Semêdo Luzia Teixeira de Ribeiro da Silva Antonio Jorge 《World journal of microbiology & biotechnology》2004,20(3):225-229
A promising producer of bioactive compounds isolated from a Brazilian tropical soil was tested for its range of antimicrobial
activities. Strain 606, classified as Streptomyces sp., could not be identified up to species level, suggesting a possible new taxon. The supernatant and 10 extracts and fractions,
obtained by extraction and chromatographic techniques, presented antimicrobial activity using antibiograms. The methanolic
fraction was highly active against pathogenic bacteria, phytopathogenic fungi and the human pathogenic yeast Candida albicans. It also possessed high antiviral activity inhibiting the propagation of an acyclovir-resistant herpes simplex virus type
1 strain on HEp-2 cells at non-cytotoxic concentration. The strong cytotoxic effect suggests an antitumour action.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
W Y Mok R C Luiz?o M do S Barreto da Silva 《Applied and environmental microbiology》1982,44(3):570-575
A total of 2,886 bats captured in the Amazon Basin of Brazil were processed for the isolation of fungi. From the livers, spleens, and lungs of 155 bats (5.4%), 186 fungal isolates of the genera Candida (123 isolates), Trichosporon (26 isolates), Torulopsis (25 isolates), Kluyveromyces (11 isolates), and Geotrichum (1 isolate) were recovered. Seven known pathogenic species were present: Candida parapsilosis, C. guilliermondii, C. albicans, C. stellatoidea, C. pseudotropicalis, Trichosporon beigelii, and Torulopsis glabrata. Twenty-three culture-positive bats showed identical fungal colonization in multiple organs or mixed colonization in a single organ. The fungal isolation rates for individual bat species varied from 1 fungus per 87 bats to 3 fungi per 13 bats, and the mycoflora diversity for members of an individual fungus-bearing bat species varied from 16 fungi per 40 bats to 7 fungi per 6 bats. Of the 38 fungal species isolated, 36 had not been previously described as in vivo bat isolates. Of the 27 culture-positive bat species, 21 had not been previously described as mammalian hosts for medically or nonmedically important fungi. 相似文献
3.
Maria João Feio Trefor B. Reynoldson Verónica Ferreira Manuel Augusto S. Graça 《Hydrobiologia》2007,579(1):55-68
We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive
model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to
September 2001. Fifty-five sites were identified as “Reference sites” and 20 sites were used as “Test sites” to test the model.
At each site we also measured 40 habitat variables to characterize water physics and chemistry, habitat type, land use, stream
hydrology and geographic location. Macroinvertebrates were generally identified to species or genus level; a total of 207
taxa were found. By Unweighted Pair Group Method with Arithmetic mean (UPGMA) clustering and analysis of species contribution
to similarities percentage (SIMPER), two groups of reference sites were established. Using Discriminant Analysis (stepwise
forward), four variables correctly predicted 78% of the reference sites to the appropriate group: stream order, pool quality,
substrate quality and current velocity. Test sites’ environmental quality was established from their relative distance to
reference sites, in MDS ordination space, using a series of bands (BEAST methodology). The model performed well at upstream
sites, but at downstream sites it was compromised by the lack of reference sites. As with the English RIVPACS predictive model,
the Mondego model should be continually improved with the addition of new reference sites. The adaptation of the Mondego model
methodology to the Water Framework Directive is possible and would consist mainly of the integration of the WFD typology and
increasing the number of ellipses that define quality bands.
Handling editor: K. Martens 相似文献
4.
Fine root distribution of trees and understory in mature stands of maritime pine (Pinus pinaster) on dry and humid sites 总被引:2,自引:0,他引:2
Maritime pine (Pinus pinaster) is the main tree cropping species in the Landes of Gascogne forest range in south western France. Soils are nutrient poor, sandy podzosols and site fertility is determined essentially by organic matter content and depth of water table, which is known to limit root growth. We hypothesised, with an ultimate goal of constructing a nutrient uptake model applicable to this region, that the organic top horizons together with the depth of the water table should be the most important parameters related to fine root distribution and presence of associated mycorrhiza. To test this hypothesis, we compared two adult Pinus pinaster stands, contrasting in depth of water table and soil fertility and evaluated fine roots (diameter ≤2 mm) of understory species and fine roots and ectomycorrhizal morphotypes of Pinus pinaster down to 1.2 m, using a soil corer approach. Total fine root biomass of Pinus pinaster was not significantly different between both sites (3.6 and 4.5 t ha−1 for the humid, respectively, dry site), but root distribution was significantly shallower and root diameter increased more with depth at the humid site, presumably due to more adverse soil conditions as related to the presence of a hardpan, higher amount of aluminium oxides and / or anoxia. Fine roots of Pinus pinaster represented only about 30% of total fine root biomass and 15% of total fine root length, suggesting that the understory species cannot be ignored with regards to competition for mineral nutrients and water. A comparison of the ectomycorrhizal morphotypes showed that the humid site could be characterised by a very large proportion of contact exploration types, thought to be more relevant in accessing organic nutrient sources, whereas the dry site had a significantly higher proportion of both long-distance and short-distance exploration types, the latter of which was thought to be more resistant to short-term drought periods. These results partly confirm our hypothesis on root distribution as related to the presence of soil mineral nutrients (i.e. in organic matter), point out the potential role of understory plant species and ectomycorrhizal symbiosis and are a valuable step in building a site-specific nutrient uptake model. 相似文献
5.
Augusto Pessina 《Cytotechnology》1993,12(1-3):127-135
6.
After c. 30 years without sighting or capture, Anthias salmopunctatus was rediscovered at the type locality, St Peter and St Paul's Rocks, Mid-Atlantic Ridge. To date, the known distribution is restricted to depths varying from 35 to 55 m in vertical drop offs around the perimeter of the islands ( c. 400 m). This may be the smallest geographic range known for a marine fish species. 相似文献
7.
Competition from native soil rhizobia is likely to be an important factor limiting Phaseolus vulgaris L. inoculant response in Latin America. We used UMR 1116, a nod
+ fix– natural mutant of Rhizobium leguminosarum bv phaseoli strain CC511, as a reference strain to study competition for nodulation sites in this species. When P. vulgaris cv Carioca was planted in soils containing different proportions of UMR 1116 and the effective and competitive strain UMR 1899, UMR 1116 occupied more than 50% of the nodules at all inoculant ratios tested, though increasing the proportion of UMR 1899 in the inoculant did enhance the number and percentage of effective nodules and plant dry weight. Sixty two strains of bean rhizobia were tested in competition with UMR 1116. An inoculant ratio of 1:1 was used, with all strains applied to the soil rather than to seeds. Strains varied in the number and percentage of effective nodules produced in competition with UMR 1116, and in plant dry weight, and there was a strong correlation between variation in each of these traits and plant N accumulation. Seven of the strains (UMR 1073, 1084, 1102, 1125, 1165, 1378 and 1384) were identified as both superior in competitive ability and active in N2 fixation. Site of placement of the inoculant and ambient temperature influenced strain response.Journal paper 16736, Agricultural Experiment Station, University of Minnesota, St. Paul, MN 55108, USA 相似文献
8.
The present paper describes a simple technique that hardens the shell of nuts and makes the use of a tool to crack them open more compelling. Walnuts were coated with a dough of sawdust and nontoxic white glue in different combinations; they were tested for hardness by using machines normally used to test different kinds of wood. Data on relative hardness for uncoated walnuts and walnuts coated with dough of two different combinations are presented. The coated walnuts were significantly harder to break than the uncoated ones, whereas no significant difference was found when comparing the hardness of two types of coated walnuts. Furthermore, observations on a captive group of tufted capuchins (Cebus apella) are described. The monkeys needed significantly more time to break open the coated walnuts. Early results show that coated walnuts may favor acquistion of tool use skills in a juvenile capuchin. 相似文献
9.
10.
O Augusto C L Weingrill S Schreier H Amemiya 《Archives of biochemistry and biophysics》1986,244(1):147-155
Kinetic, circular dichroism, and NADH and NADPH fluorescence quenching studies indicate that these compounds interact with the antimalarial drug primaquine (PQ). The affinity of both pyridine nucleotides for PQ is similar. The data are in contrast with a previous report (Thornalley et al. (1983) Biochem. Pharmacol. 32, 3571-3575) suggesting specificity for the interaction with NADPH. The complex was seen to facilitate electron transfer from NAD(P)H to oxygen, generating oxygen-free radicals which were detected by the spin-trapping technique and to flavin nucleotides, giving rise to flavin semiquinone radicals which were demonstrated by direct ESR spectroscopy under anaerobic conditions. A twofold increase in oxygen uptake and hydroxyl radical generation by the NAD(P)H-PQ complex was observed in the presence of hemoglobin. This effect was independent of heme concentration (in the range 1 X 10(-5)-1 X 10(-4) M) and oxidation state of the iron. Under anaerobic conditions, the NAD(P)H-PQ complex reduces Fe-III to Fe-II hemoglobin, and under aerobic conditions about 65% of the heme chromophore is irreversibly destroyed. Superoxide dismutase inhibits hydroxyl radical generation by the NAD(P)H-PQ pair; this effect is not observed in the presence of hemoglobin. In the presence of microsomes there is a 10-fold increase in both oxygen consumption and hydroxyl radical generation by the NAD(P)H-PQ pair. The fact that both pyridine nucleotides are active, and the inability of SKF 525A in decreasing hydroxyl radical generation, suggests that microsomal reductases are involved in the catalysis. 相似文献