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排序方式: 共有191条查询结果,搜索用时 15 毫秒
91.
Christensen MJ Bennett RJ Ansari HA Koga H Johnson RD Bryan GT Simpson WR Koolaard JP Nickless EM Voisey CR 《Fungal genetics and biology : FG & B》2008,45(2):84-93
A fundamental hallmark of fungal growth is that vegetative hyphae grow exclusively by extension at the hyphal tip. However, this model of apical growth is incompatible with endophyte colonization of grasses by the symbiotic Neotyphodium and Epichlo? species. These fungi are transmitted through host seed, and colonize aerial tissues that develop from infected shoot apical meristems of the seedling and tillers. We present evidence that vegetative hyphae of Neotyphodium and Epichlo? species infect grass leaves via a novel mechanism of growth, intercalary division and extension. Hyphae are attached to enlarging host cells, and cumulative growth along the length of the filament enables the fungus to extend at the same rate as the host. This is the first evidence of intercalary growth in fungi and directly challenges the centuries-old model that fungi grow exclusively at hyphal tips. A new model describing the colonization of grasses by clavicipitaceous endophytes is described. 相似文献
92.
Sefika C Mizrak Bart M Gadella Hatice Erdost Aytekin Ozer Ana MM van Pelt Federica MF van Dissel-Emiliani 《Reproductive biology and endocrinology : RB&E》2008,6(1):1-9
Background
The placenta is an important site for iron metabolism in humans. It transfers iron from the mother to the fetus. One of the major iron transport proteins is transferrin, which is a blood plasma protein crucial for iron uptake. Its localization and expression may be one of the markers to distinguish placental dysfunction.Methods
In the experimental study we used antibody preparation, mass spectrometric analysis, biochemical and immunocytochemical methods for characterization of transferrin expression on the human choriocarcinoma cell line JAR (JAR cells), placental lysates, and cryostat sections. Newly designed monoclonal antibody TRO-tf-01 to human transferrin was applied on human placentae from normal (n = 3) and abnormal (n = 9) pregnancies.Results
Variations of transferrin expression were detected in villous syncytiotrophoblast, which is in direct contact with maternal blood. In placentae from normal pregnancies, the expression of transferrin in the syncytium was significantly lower (p < 0.001) when compared to placentae from abnormal ones (gestational diabetes, pregnancy induced hypertension, drug abuse).Conclusion
These observations suggest that in the case of abnormal pregnancies, the fetus may require higher levels of transferrin in order to prevent iron depletion due to the stress from the placental dysfunction. 相似文献93.
Olfa Boussaada Jihène Chriaa Rym Nabli Samia Ammar Dhouha Saidana Mohamed Ali Mahjoub Imed Chraeif Ahmed Noureddine Helal Zine Mighri 《World journal of microbiology & biotechnology》2008,24(8):1289-1296
Antimicrobial activity of methanolic extracts obtained from the aerial parts of Evax pygmaea was tested against five bacteria and two strains of phytopathogenic fungi using the agar diffusion and broth microdilution
methods. Antioxidant properties were evaluated through the ability of the different fractions to scavenge the stable ABTS
(2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) and DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals. The TEAC (Trolox
Equivalent Antioxidant Capacity) and IC50 values of the fractions were calculated and compared. The experimental data indicated that all fractions exhibit moderate
to appreciable antibacterial activities against all Gram-positive cocci and Gram-negative rods except Pseudomonas aeruginosa, but no antifungal activity was observed. Ethyl acetate and methanol fractions were found to cause significant free radical-scavenging
effects in both assays. These results may suggest that E. pygmaea could be used as a natural preservative ingredient in the food and/or pharmaceutical industries. 相似文献
94.
Alu insertion polymorphisms in NW Africa and the Iberian Peninsula: evidence for a strong genetic boundary through the Gibraltar Straits 总被引:11,自引:0,他引:11
Comas D Calafell F Benchemsi N Helal A Lefranc G Stoneking M Batzer MA Bertranpetit J Sajantila A 《Human genetics》2000,107(4):312-319
An analysis of 11 I Alu insertion polymorphisms (ACE, TPA25, PV92, APO, FXIIIB, D1, A25, B65, HS2.43, HS3.23, and HS4.65) has been performed in several NW African (Northern, Western, and Southeastern Moroccans, Saharawi; Algerians; Tunisians) and Iberian (Basques, Catalans, and Andalusians) populations. Genetic distances and principal component analyses show a clear differentiation of NW African and Iberian groups of samples, suggesting a strong genetic barrier matching the geographical Mediterranean Sea barrier. The restriction to gene flow may be attributed to the navigational hazards across the Straits, but cultural factors must also have played a role. Some degree of gene flow from sub-Saharan Africa can be detected in the southern part of North Africa and in Saharawi and Southeastern Moroccans, as a result of a continuous gene flow across the Sahara desert that has created a south-north cline of sub-Saharan Africa influence in North Africa. Iberian samples show a substantial degree of homogeneity and fall within the cluster of European-based genetic diversity. 相似文献
95.
Helal Mohammed Igel-Egalon Angélique Lakmeche Abdelkader Mazzocco Pauline Perrillat-Mercerot Angélique Pujo-Menjouet Laurent Rezaei Human Tine Léon M. 《Journal of mathematical biology》2019,78(1-2):57-81
Journal of Mathematical Biology - Alzheimer’s disease (AD) is a neuro-degenerative disease affecting more than 46 million people worldwide in 2015. AD is in part caused by the accumulation of... 相似文献
96.
Safaa M. Kishk Kirsty J. McLean Sakshi Sood Mohamed A. Helal Mohamed S. Gomaa Ismail Salama Samia M. Mostafa Luiz Pedro S. de Carvalho Andrew W. Munro Claire Simons 《Bioorganic & medicinal chemistry》2019,27(8):1546-1561
The rise in multidrug resistant (MDR) cases of tuberculosis (TB) has led to the need for the development of TB drugs with different mechanisms of action. The genome sequence of Mycobacterium tuberculosis (Mtb) revealed twenty different genes coding for cytochrome P450s. CYP121A1 catalyzes a CC crosslinking reaction of dicyclotyrosine (cYY) producing mycocyclosin and current research suggests that either mycocyclosin is essential or the overproduction of cYY is toxic to Mtb. A series of 1,4-dibenzyl-2-imidazol-1-yl-methylpiperazine derivatives were designed and synthesised as cYY mimics. The derivatives substituted in the 4-position of the phenyl rings with halides or alkyl group showed promising antimycobacterial activity (MIC 6.25?μg/mL), with the more lipophilic branched alkyl derivatives displaying optimal binding affinity with CYP121A1 (iPr KD?=?1.6?μM; tBu KD?=?1.2?μM). Computational studies revealed two possible binding modes within the CYP121A1 active site both of which would effectively block cYY from binding. 相似文献
97.
Andreas Krupke Wiebke Mohr Julie LaRoche Bernhard M Fuchs Rudolf I Amann Marcel MM Kuypers 《The ISME journal》2015,9(7):1635-1647
Symbiotic relationships between phytoplankton and N2-fixing microorganisms play a crucial role in marine ecosystems. The abundant and widespread unicellular cyanobacteria group A (UCYN-A) has recently been found to live symbiotically with a haptophyte. Here, we investigated the effect of nitrogen (N), phosphorus (P), iron (Fe) and Saharan dust additions on nitrogen (N2) fixation and primary production by the UCYN-A–haptophyte association in the subtropical eastern North Atlantic Ocean using nifH expression analysis and stable isotope incubations combined with single-cell measurements. N2 fixation by UCYN-A was stimulated by the addition of Fe and Saharan dust, although this was not reflected in the nifH expression. CO2 fixation by the haptophyte was stimulated by the addition of ammonium nitrate as well as Fe and Saharan dust. Intriguingly, the single-cell analysis using nanometer scale secondary ion mass spectrometry indicates that the increased CO2 fixation by the haptophyte in treatments without added fixed N is likely an indirect result of the positive effect of Fe and/or P on UCYN-A N2 fixation and the transfer of N2-derived N to the haptophyte. Our results reveal a direct linkage between the marine carbon and nitrogen cycles that is fuelled by the atmospheric deposition of dust. The comparison of single-cell rates suggests a tight coupling of nitrogen and carbon transfer that stays balanced even under changing nutrient regimes. However, it appears that the transfer of carbon from the haptophyte to UCYN-A requires a transfer of nitrogen from UCYN-A. This tight coupling indicates an obligate symbiosis of this globally important diazotrophic association. 相似文献
98.
99.
Resumé Les auteurs ont étudié la composition chimique (N, substances humiques, lignine) de copeaux de bois blanc exposés à l'air libre depuis 2 à 10 ans, ainsi que leur type de peuplement fongique. En l'absence de lignivore, le pH, les taux de lignine et d'N s'élèvent et il se forme des quantités modérées d'humus à forte capacité d'échange. Dans le cas contraire, on voit apparaître, en abondance, des substances humiques peu condensées et la matière organique subit une évolution rappelant celle du mor.Avec la collaboration technique de Melle. M. Clet.Kononova, dans sa monographie5, signale de Troussov (1916) une étude que nous n'avons pas eu en mains. 相似文献
100.
Priming Endothelial Cells With a Melanoma‐Derived Extracellular Matrix Triggers the Activation of αvβ3/VEGFR2 Axis 下载免费PDF全文