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131.
132.
Relationship between genotype and soil environment during colonization of poplar roots by mycorrhizal and endophytic fungi 总被引:1,自引:0,他引:1
Leszek Karliński Maria Rudawska Barbara Kieliszewska-Rokicka Tomasz Leski 《Mycorrhiza》2010,20(5):315-324
Poplars are among the few tree genera that can develop both ectomycorrhizal (ECM) and arbuscular (AM) associations; however,
variable ratios of ECM/AM in dual mycorrhizal colonizations were observed in the roots of a variety of poplar species and
hybrids. The objective of our study was to analyze the effect of internal and external factors on growth and dual AM and ECM
colonization of poplar roots in three 12–15-year-old common gardens in Poland. We also analyzed the abundance of nonmycorrhizal
fungal endophytes in the poplar roots. The Populus clones comprised black poplars (Populus deltoides and P. deltoides × Populus nigra), balsam poplars (Populus maximowiczii × Populus trichocarpa), and a hybrid of black and balsam poplars (P. deltoides × P. trichocarpa). Of the three sites that we studied, one was located in the vicinity of a copper smelter, where soil was contaminated with
copper and lead. Poplar root tip abundance, mycorrhizal colonization, and soil fungi biomass were lower at this heavily polluted
site. The total mycorrhizal colonization and the ratio of ECM and AM colonization differed among the study sites and according
to soil depth. The influence of Populus genotype was significantly pronounced only within the individual study sites. The contribution of nonmycorrhizal fungal endophytes
differed among the poplar clones and was higher at the polluted site than at the sites free of pollution. Our results indicate
that poplar fine root abundance and AM and ECM symbiosis are influenced by environmental conditions. Further studies of different
site conditions are required to characterize the utility of poplars for purposes such as the phytoremediation of polluted
sites. 相似文献
133.
Tomasz Janeczko Jadwiga Dmochowska-Gładysz Edyta Kostrzewa-Susłow 《World journal of microbiology & biotechnology》2010,26(11):2047-2051
Enantiospecific microbial reduction of bicyclic ketones was described. Racemic Wieland–Miescher (1) and Hajos–Parrish (2) ketones were used as substrates. In a 4-h biotransformation of Hajos–Parrish ketone (2) using the strain of Didymosphaeria igniaria an optically pure ketone (R)-2 was obtained, whereas the (S)-2 ketone underwent reduction to (4aS,5S)-4 alcohol with 100% of enantiomeric excess and with over 60% of diastereoisomeric excess. Jones oxidation of the alcohol obtained
in the biotransformation gave an optically pure ketone (S)-2. Enzymatic system of Coryneum betulinum reduced the (R)-2 ketone to (4aR,5S)-4 alcohol with a high enantiomerical purity in a 6-day reaction. Wieland-Miescher (1) ketone was transformed by these microorganisms in an analogous way, but the reaction times were longer. 相似文献
134.
Zdzisław Zakęś Barbara Jankowska Sylwia Jarmołowicz Tomasz Żmijewski Konrad Partyka Krystyna Demska-Zakęś 《Reviews in Fish Biology and Fisheries》2010,20(3):389-401
Juvenile tench (initial weight of about 57 g) were fed feed supplemented with fish oil (group FO), linseed oil (group LO),
peanut oil (group PO), or rapeseed oil (group RO) containing 47% protein and 12% fat for 55 days. The inclusion of the tested
oils was 50 g kg−1 (42% total crude lipids in diets). No significant differences were noted in the fish growth performance. The proximate composition
of the whole fish bodies and the viscera (water, protein, fat, ash) was similar in all the dietary treatments (P > 0.05). Differences were noted only with regard to the ash content of the fillets (P < 0.05). The analysis of the fatty acids profiles of tench (whole fish) indicated there were significant differences in the
total content of monoenoic and polyenoic (PUFA) acids. Significant differences were also noted with regard to n-3 PUFA and
n-6 PUFA. Consequently, the ratio of n-3/n-6 acids ranged from 1.6 (group PO) to 2.08 (group LO; P < 0.05). The feed applied was not confirmed to have had an impact on the fatty acids profile of the tench fillets. There
was a statistically significant intergroup difference in the content of saturated fatty acids (SFA) in tench viscera. In the
fish fed vegetable oils supplemented diets, the level of SFA was lower (P < 0.05). 相似文献
135.
Tomasz Borowski Valentin Georgiev Per E. M. Siegbahn 《Journal of molecular modeling》2010,16(11):1673-1677
Catalytic cycle intermediates of a representative extradiol dioxygenase, homoprotocatechuate 2,3-dioxygenase (HPCD), have
recently been characterized in crystallo by Kovaleva and Lipscomb. The structures of the identified species indicate that
the process of inserting oxygen into the catechol ring occurs stepwise, and involves an Fe(II)-alkylperoxo intermediate and
its O–O cleavage product: a gem diol species. In general, these findings corroborate the results of our previous computational
studies; however, the fact that the gem diol species is stable enough to be observed in the crystal form seems to be at odds
with the computational mechanistic data, which suggest that this intermediate should very readily and spontaneously convert
to the epoxide species. The key question then becomes what is actually observed in the X-ray experiments. Here we report additional
computational studies undertaken with the hope of clarifying this issue. The results obtained for active site models hosting
both the native and the alternative (4-sulfonylcatechol) substrate indicate that the stability of the gem diol species is
substantially increased if an electron and a proton are added. If this occurs somehow, the lifetime of the intermediate should
be sufficient to observe it. 相似文献
136.
Pawel Mazur Tomasz Magdziarz Andrzej Bak Zdzislaw Chilmonczyk Teresa Kasprzycka-Guttman Irena Misiewicz-Krzemińska Katarzyna Skupińska Jaroslaw Polanski 《Journal of molecular modeling》2010,16(7):1205-1212
Isothiocyanates (ITC) are well-known chemopreventive agents extracted from vegetables. This activity results from the activation
of human oxidoreductase. In this letter, the uncompetitive activatory mechanism of ITC was investigated using docking and
molecular dynamics simulations. This indicates that NAD(P)H:quinone oxidoreductase can efficiently improve enzyme-substrate
recognition within the catalytic site if the ITC activator supports the interaction in the uncompetitive binding site. 相似文献
137.
138.
Borrelia burgdorferi spirochetes are an infectious agent of Lyme borreliosis. The aim of our studies was to investigate the fate of engulfed B. burgdorferi cells in L-929 mouse fibroblasts and to observe development of intracellular infection in vitro after 2 and 48 h. Electron microscopic studies reveal consecutive stages of B. burgdorferi spirochetes penetration to mouse fibroblasts in vitro. It has been observed, as a first step attachment and engulfment of spirochetes followed by formation of vacuoles. After 48 hours of infection, vacuoles of fibroblastic cells have been seen full of B. burgdorferi bacteria and latter they have been released from infected cells to extracellular space. It can be the evidence that B. burgdorferi multiply intracellulary. 相似文献
139.
P. aeruginosa rods are opportunistic pathogens responsible generally for nosocomial infections. Resistance to carbapenems, observed among them, is a serious threat due to ability to be transmitted between bacterial species. The aim of our study was to evaluate the usefulness of PCR-RAPD technique in typing of 16 carbapenem-resistant P. aeruginosa strains isolated in 2007 from different patients of University HospitalNo. 1 of dr A. Jurasz Collegium Medicum of L. Rydygier in Bydgoszcz Nicolaus Copernicus University in Toruń. Study shows increasing frequency of isolation that type of strains when compared to 2006. Percentage of carbapenem-resistant isolates raised from 12,4% in 2006 to 22.9% in 2007. The majority of examined strains were obtained from patients of the Intensive Care Units (25.0%) and were isolated from bronchoalveolar lavage (25.0%), urine (25.0%) and wound swabs (18.8%) samples. Examined P. aeruginosa strains demonstrated resistance to doripenem (81.3%) and piperacillin (75.0%) and susceptibility to colistin (100.0%), amikacin (81.3%), netilmicin and norfloxacin (75.0% each). Using PCR-RAPD amplification with 208 and 272 primers, 14 and 16 DNA patterns were obtained, respectively. Usefulness of PCR-RAPD in carbapenem-resistant P. aeruginosa strains typing was proved in case of strains presenting similar and/or different antimicrobials susceptibility patterns. 相似文献
140.
Aucina A Rudawska M Leski T Skridaila A Riepsas E Iwanski M 《Applied and environmental microbiology》2007,73(15):4867-4873
We report the effects of pine and oak litter on species composition and diversity of mycorrhizal fungi colonizing 2-year-old Pinus sylvestris L. seedlings grown in a bare-root nursery in Lithuania. A layer of pine or oak litter was placed on the surface of the nursery bed soil to mimic natural litter cover. Oak litter amendment appeared to be most favorable for seedling survival, with a 73% survival rate, in contrast to the untreated mineral bed soil (44%). The concentrations of total N, P, K, Ca, and Mg were higher in oak growth medium than in pine growth medium. Relative to the control (pH 6.1), the pH was lower in pine growth medium (5.8) and higher in oak growth medium (6.3). There were also twofold and threefold increases in the C content of growth medium with the addition of pine and oak litter, respectively. Among seven mycorrhizal morphotypes, eight different mycorrhizal taxa were identified: Suillus luteus, Suillus variegatus, Wilcoxina mikolae, a Tuber sp., a Tomentella sp., Cenococcum geophilum, Amphinema byssoides, and one unidentified ectomycorrhizal symbiont. Forest litter addition affected the relative abundance of mycorrhizal symbionts more than their overall representation. This was more pronounced for pine litter than for oak litter, with 40% and 25% increases in the abundance of suilloid mycorrhizae, respectively. Our findings provide preliminary evidence that changes in the supply of organic matter through litter manipulation may have far-reaching effects on the chemistry of soil, thus influencing the growth and survival of Scots pine seedlings and their mycorrhizal communities. 相似文献