共查询到20条相似文献,搜索用时 31 毫秒
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Kizilcikli I Kurt YD Akkurt B Genel AY Birteksöz S Otük G Ulküseven B 《Folia microbiologica》2007,52(1):15-25
Thirty-four thiosemicarbazones and S-alkyl thiosemicarbazones, and some of their Zn(II) and Pd(II) complexes were obtained and purified to investigate antimicrobial activity. MIC values of the compounds were determined by the disc diffusion method against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri, Staphylococcus aureus, S. epidermidis, and Candida albicans. The thiosemicarbazones show antibacterial and antifungal effects in free ligand and metal-complex form. Picolinaldehyde-S-methyl- and -S-benzylthiosemicarbazones did not affect the tested microorganisms but their Zn(II) complexes showed selective activity. The antimicrobial activity is relatively high in Me2SO, but the antimicrobial potential is changed in a certain range with Me2SO, HCONMe2, EtOH and CHCl3. 相似文献
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D F Harrison 《BMJ (Clinical research ed.)》1986,293(6544):405-406
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Some exotic plants are able to invade habitats and attain higher fitness than native species, even when the native species
are closely related. One explanation for successful plant invasion is that exotic invasive plant species receive less herbivory
or other enemy damage than native species, and this allows them to achieve rapid population growth. Despite many studies comparing
herbivory and fitness of native and invasive congeners, none have quantified population growth rates. Here, we examined the
contribution of herbivory to the population dynamics of the invasive species, Lespedeza cuneata, and its native congener, L. virginica, using an herbivory reduction experiment. We found that invasive L. cuneata experienced less herbivory than L. virginica. Further, in ambient conditions, the population growth rate of L. cuneata (λ = 20.4) was dramatically larger than L. virginica (λ = 1.7). Reducing herbivory significantly increased fitness of only the largest L. virginica plants, and this resulted in a small but significant increase in its population growth rate. Elasticity analysis showed that
the growth rate of these species is most sensitive to changes in the seed production of small plants, a vital rate that is
relatively unaffected by herbivory. In all, these species show dramatic differences in their population growth rates, and
only 2% of that difference can be explained by their differences in herbivory incidence. Our results demonstrate that to understand
the importance of consumers in explaining the relative success of invasive and native species, studies must determine how
consumer effects on fitness components translate into population-level consequences.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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The character of inheritance of the morphological traits of spike and grain color and morphometric parameters of the grain in simple and backcross F1 and F2 hybrids of spelt and soft wheat has been investigated. The experiments confirmed that single homologous genes determine the trait of grain width in different species of wheat. Incomplete dominance of the gene that determines the trait of grain length has been revealed. The increase of the dosage of genes from one wheat species in a backcross hybrid has been shown to increase the deviation from the other species and to bring the values of the quantitative parameters of the grain closer to the values for the saturating species. Splitting of the spike color trait in the F2 offspring has been shown to follow the 15: 1 dihybrid cross scheme and to be controlled by two dominant homologous genes. 相似文献
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A new and convenient method was developed to separate and identify exo- and endoinulinase from Aspergillus ficuum by native polyacrylamide gel electrophoresis. Eight protein bands were obtained. Three bands were identified as exoinulinase, and two bands were endoinulinase, by using TLC and HPLC. The five bands were all detected as glycoproteins with the sensitive periodic acid-silver stain. Received: 3 July 2002 / Accepted: 25 September 2002 相似文献
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N. V. Kichemazova E. N. Bukharova N. Yu. Selivanov I. A. Bukharova L. V. Karpunina 《Applied Biochemistry and Microbiology》2017,53(3):325-330
Two new bacterial biopolymers (exopolysaccharides), ancylan and xylophilan, have been isolated and characterized. The optimal parameters for ancylan and xylophilan production under laboratory conditions were selected. Their physicochemical properties and effects on microorganisms (bacteria, fungi, and ciliates) were studied. The results suggest the potential application of these new exopolysaccharides in medicine and veterinary science. 相似文献
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A model is proposed for the regulation of the number of copies of drug resistance genes per host cell by their dissociation and reassociation with transfer factors. 相似文献
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Phytophthora nicotianae causes substantial economic losses in most countries where tobacco is produced. At present, the control of P. nicotianae mainly depends on chemical methods, with considerable environmental and
health issues. We investigated the effects of ethanol extracts from Scutellaria baicalensis Georgi (SBG) and Magnolia officinalis (MO). On mycelial growth, sporangium formation, and zoospore release of P. nicotianae. Both
extracts inhibited the growth of P. nicotianae, with mycelial growth inhibition rates of 88.92% and 93.92%, respectively, at 40 mg/mL, and EC50 values of 5.39 and 5.74 mg/mL, respectively. The underlying mechanisms were the
inhibition of sporangium formation, the reduction of zoospore number, and the destruction of the mycelium
structure. At an SBG extract concentration of 16.17 mg/mL, the inhibition rates for sporangia and zoospores were
98.66% and 99.39%, respectively. At an MO extract concentration of 2.87 mg/mL, the production of sporangia
and zoospores was completely inhibited. The hyphae treated with the two plant extracts showed different degrees
of deformation and damage. Hyphae treated with SBG extract showed adhesion and local swelling, whereas treatment with MO extract resulted in broken hyphae. Mixture of the extracts resulted in a good synergistic effect. 相似文献
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Elizabeth Jaya Jiancheng Song John Clemens Paula E. Jameson 《Plant Growth Regulation》2011,64(1):53-61
Metrosideros
excelsa and Eucalyptus occidentalis exhibit different strategies prior to flowering—the former passes through a long juvenile phase and must acquire a degree
of architectural complexity to flower, whereas the latter flowers precociously even on stems still exhibiting juvenile foliage.
As expediting flowering is of interest to breeders and horticulturalists alike we compared these species by growing plants
with two branch architecture treatments in factorial combination with two growth environments. Plants were either allowed
to branch freely or constrained to a single stem before subsequently being allowed to branch; one environment was inductive
for flowering and the other not. Three meristem identity genes (the equivalents of LEAFY, APETALA1 and TERMINAL FLOWER1) were used as indicators of flowering. Constraining E. occidentalis plants to a single stem delayed the onset of the main flush of flowering in contrast to M. excelsa, although in both species a complex interaction between branching and environment occurred. We show that the complexity of
the architecture can impact on production of flowers and can be used to expedite or enhance flowering for breeding purposes,
but this is dependent on the species. AP1 appears to be a useful marker not just for floral organ differentiation but also as an indicator of floral induction having
occurred. 相似文献
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Fábio Vieira dos Santos Vanessa Jaqueline da Silva Vieira dos Santos Maria José Farias Suzana de Fátima Paccola Mesquita Maria Aparecida Maciel Angelo da Cunha Pinto Ilce Mara de Syllos Cólus 《Biologia》2008,63(3):327-331
Croton cajucara Benth. (‘sacaca’) is a tree of the Euphorbiaceae family, native to the Amazon region in northern Brazil, where it is widely used in the popular
treatment of various diseases. Its active principle, the terpenoid trans-dehydrocrotonin, has been credited with a variety of medical properties, including antiulcer, antiinflammatory, antitumor,
antimutagenic and hypoglycemic activity. In this investigation, possible mutagenic and antimutagenic effects were evaluated
in treatments using methanol extract of this plant on Swiss Albino mice by examining their peripheral blood cells for micronuclei.
In these tests, the material obtained by methanol extraction of C. cajucara tree bark was administered to the mice by gavage. None of the doses evaluated in this study presented mutagenicity. Analysis
of the results obtained from studies evaluating antimutagenicity revealed protection against the chemotherapeutic agent cyclophosphamide
for the two highest doses used. 相似文献
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Göran I. Ågren 《Ecology letters》2004,7(3):185-191
Evolution has set biochemical constraints on the chemical composition of living organisms. These constraints seem to lead to increases in N : C and P : C ratios with increasing relative growth rate for all types of organisms. The N : P ratio also seems to decrease with relative growth rate for heterotrophs whereas autotrophs may show a more complex behaviour. Here I will show that, from biochemical considerations, N : C should increase linearly and P : C quadratically with relative growth rate in autotrophs with the consequence that N : P increases at low relative growth rates, passes a maximum and then decreases at high relative growth rates. These predictions are verified against observations for a freshwater alga (Selenastrum minutum) and a tree seedling (Betula pendula). Changes in temperature, light or other factors that affect the growth rate of autotrophs interact with nutrient supply in such a way that there are no simple rules for as to how N : P will change. 相似文献