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Intraspecific competition of endophyte infected vs uninfected plants of two woodland grass species 总被引:3,自引:0,他引:3
Grass endophytes (Clavicipitaceae, Ascomycota) are generally considered to be mutualists which increase the host's fitness. Infected plants are often more persistent and competitive than uninfected plants, influencing population dynamics and plant community diversity. However, most of this empirical evidence is based on studies focusing on agronomically important grass species such as tall fescue or perennial ryegrass and their implications for livestock and man-made habitats. Recent studies indicate that endophyte-plant associations may be more variable, ranging from parasitic to mutualistic. In the present study, we investigated the influence of endophyte infection on two wild woodland grasses, which are naturally infected with distinct fungal endophytes: Brachypodium sylvaticum with Epichloë sylvatica and Bromus benekenii with Epichloë bromicola . An intraspecific competition experiment was conducted over two growing seasons in the greenhouse and in an experimental garden. At first harvest (after 12 weeks growing), endophyte infection had a significant negative effect on above ground dry matter yield (DMY) of B. sylvaticum , but a significant positive effect on DMY of Br. benekenii under competition. The same differential effects on DMY and on total seed number were also observed at final harvest (after 62 weeks growing). Results from Br. benekenii were consistent with our hypothesis of increased competitive abilities of infected plants in nature which could explain the high infection rate observed in natural populations. In contrast, this explanation does not hold true for B. sylvaticum , and other factors such as increased herbivore and pathogen resistance together with frequent horizontal transmission may be responsible for the very high incidence of this association in nature. Our results confirm previous predictions that beneficial effects of endophyte infection in wild grasses can vary for different grass species, even in comparable habitats. 相似文献
34.
Hugo R. Arias Avraham Rosenberg Katarzyna M. Targowska-Duda Dominik Feuerbach Xiao Juan Yuan Krzysztof Jozwiak Ruin Moaddel Irving W. Wainer 《The international journal of biochemistry & cell biology》2010,42(9):1525-1535
The interaction of ibogaine and phencyclidine (PCP) with human (h) α3β4-nicotinic acetylcholine receptors (AChRs) in different conformational states was determined by functional and structural approaches including, radioligand binding assays, Ca2+ influx detections, and thermodynamic and kinetics measurements. The results established that (a) ibogaine inhibits (±)-epibatidine-induced Ca2+ influx in hα3β4 AChRs with ~9-fold higher potency than that for PCP, (b) [3H]ibogaine binds to a single site in the hα3β4 AChR ion channel with relatively high affinity (Kd = 0.46 ± 0.06 μM), and ibogaine inhibits [3H]ibogaine binding to the desensitized hα3β4 AChR with slightly higher affinity compared to the resting AChR. This is explained by a slower dissociation rate from the desensitized ion channel compared to the resting ion channel, and (c) PCP inhibits [3H]ibogaine binding to the hα3β4 AChR, suggesting overlapping sites. The experimental results correlate with the docking simulations suggesting that ibogaine and PCP interact with a binding domain located between the serine (position 6′) and valine/phenylalanine (position 13′) rings. This interaction is mediated mainly by van der Waals contacts, which is in agreement with the observed enthalpic contribution determined by non-linear chromatography. However, the calculated entropic contribution also indicates local conformational changes. Collectively our data suggest that ibogaine and PCP bind to overlapping sites located between the serine and valine/phenylalanine rings, to finally block the AChR ion channel, and in the case of ibogaine, to probably maintain the AChR in the desensitized state for longer time. 相似文献
35.
Karl H. Summer Dominik Klein Nada de Ruiter Josef Abel 《Biological trace element research》1989,21(1):165-169
In the present study we report on the effects of commonly used nonsteroidal antiinflammatory drugs on metallothionein (MT)
and MT-I mRNA levels. A single dose of chloroquine (100 mg/kg), diclofenac (100 mg/kg), indomethacin (10 mg/kg), or piroxicam
(100 mg/kg) was administered ip to C57B1 mice. After 18 h, MT levels were determined with a Cd-saturation radioassay. MT-I
mRNA levels were measured by Northern Blot analyses using a probe containing the mouse MT-I gene. All drugs tested caused
an increase in the MT content of the liver but not of the kidneys and lung. The lowest and highest effects were observed with
chloroquine (8 times the control value) and diclofenac (18 times), respectively. In accordance with the stimulation of MT
synthesis, increased accumulation of hepatic MT-I mRNA could be demonstrated.
These results indicate that elevated MT levels may contribute to the effectiveness of nonsteroidal antiinflammatory drugs
in the treatment of rheumatoid arthritis (RA). 相似文献
36.
Kathrin Schüller Dominik Bühler Nikolaus Plesnila 《Journal of visualized experiments : JoVE》2013,(81)
In this video publication a standardized mouse model of subarachnoid hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of Willis perforation (CWp) and proven by intracranial pressure (ICP) monitoring. Thereby a homogenous blood distribution in subarachnoid spaces surrounding the arterial circulation and cerebellar fissures is achieved. Animal physiology is maintained by intubation, mechanical ventilation, and continuous on-line monitoring of various physiological and cardiovascular parameters: body temperature, systemic blood pressure, heart rate, and hemoglobin saturation. Thereby the cerebral perfusion pressure can be tightly monitored resulting in a less variable volume of extravasated blood. This allows a better standardization of endovascular filament perforation in mice and makes the whole model highly reproducible. Thus it is readily available for pharmacological and pathophysiological studies in wild type and genetically altered mice. 相似文献
37.
Timothy A. Stammers René Coulombe Martin Duplessis Gulrez Fazal Alexandre Gagnon Michel Garneau Sylvie Goulet Araz Jakalian Steven LaPlante Jean Rancourt Bounkham Thavonekham Dominik Wernic George Kukolj Pierre L. Beaulieu 《Bioorganic & medicinal chemistry letters》2013,23(24):6879-6885
Optimization efforts on the anthranilic acid-based Thumb Pocket 2 HCV NS5B polymerase inhibitors 1 and 2 resulted in the identification of multiple structural elements that contributed to improved cell culture potency. The additive effect of these elements resulted in compound 46, an inhibitor with enzymatic (IC50) and cell culture (EC50) potencies of less than 100 nanomolar. 相似文献
38.
Bactericidal peptidoglycan recognition protein induces oxidative stress in Escherichia coli through a block in respiratory chain and increase in central carbon catabolism 下载免费PDF全文
Des R. Kashyap Marcin Kuzma Dominik A. Kowalczyk Dipika Gupta Roman Dziarski 《Molecular microbiology》2017,105(5):755-776
Mammalian Peptidoglycan Recognition Proteins (PGRPs) kill both Gram‐positive and Gram‐negative bacteria through simultaneous induction of oxidative, thiol and metal stress responses in bacteria. However, metabolic pathways through which PGRPs induce these bactericidal stress responses are unknown. We screened Keio collection of Escherichia coli deletion mutants and revealed that deleting genes for respiratory chain flavoproteins or for tricarboxylic acid (TCA) cycle resulted in increased resistance of E. coli to PGRP killing. PGRP‐induced killing depended on the production of hydrogen peroxide, which required increased supply of NADH for respiratory chain oxidoreductases from central carbon catabolism (glycolysis and TCA cycle), and was controlled by cAMP‐Crp. Bactericidal PGRP induced a rapid decrease in respiration, which suggested that the main source of increased production of hydrogen peroxide was a block in respiratory chain and diversion of electrons from NADH oxidoreductases to oxygen. CpxRA two‐component system was a negative regulator of PGRP‐induced oxidative stress. By contrast, PGRP‐induced thiol stress (depletion of thiols) and metal stress (increase in intracellular free Zn2+ through influx of extracellular Zn2+) were mostly independent of oxidative stress. Thus, manipulating pathways that induce oxidative, thiol and metal stress in bacteria could be a useful strategy to design new approaches to antibacterial therapy. 相似文献
39.
How tree morphology develops in mixed-species stands is essential for understanding and modelling mixed-stand dynamics. However, research so far focused on the morphological variation between tree species and neglected the variation within a species depending on intra- and interspecific competition. Our study, in contrast, addresses crown properties of nine mature Norway spruces (Picea abies [L.] Karst.) of a pure stand and compares them with ten spruces growing in mixture with European beech (Fagus sylvatica [L.]). The same was done with 11 pure stand beeches and 12 beeches growing in mixture with spruce. Through application of a terrestrial laser scanner and a new skeletonization approach, we deal with both species’-specific morphological traits such as branch angle, branch length, branch bending, crown volume and space occupation of branches within the crown, some of which were hardly accessible so far. Special attention is paid to distinct differences between trees growing in mixed and pure stands: for spruce, our study reveals significantly longer branches and greater crown volumes in the mixed stand when compared to the pure stand. In case of European beech, individuals growing in mixture show flatter branch angles, more distinct ramification, greater crown volumes and a lower share of a single branch’s space occupation in the total crown volume. The results show that the presented methods yield detailed information on the morphological traits analyzed in this study and that interspecific competition on its own may have a significant impact on crown structures. Implications for production ecology and stand dynamics of mixed-species forests are discussed. 相似文献
40.
Ingo Schöning Erik Grüneberg Carlos A. Sierra Dominik Hessenmöller Marion Schrumpf Wolfgang W. Weisser Ernst-Detlef Schulze 《Plant and Soil》2013,370(1-2):625-639