Membrane Transport at the Biotrophic Interface: an Overview

1989 ◽  
Vol 16 (1) ◽  
pp. 33 ◽  
Author(s):  
FA Smith ◽  
SE Smith
Keyword(s):  
Cell Wall ◽  
Membrane Transport ◽  
Nutrient Transfer ◽  
Cell Wall Metabolism ◽  
Mutualistic Symbiosis ◽  
Transfer Processes ◽  
Mycorrhizal Associations ◽  
Bidirectional Transport ◽  
Membrane Level

Many studies of interactions between the organisms which form biotrophic symbioses have concentrated on extracellular events such as signals and responses that involve modifications to cell wall metabolism. It is clear, however, that formation of a biotrophic association must also involve signals and responses at the membrane level and modifications to membrane activity resulting in changes in the transfer of nutrients. In parasitic biotrophs the modifications to membrane transport result in unidirectional transport (at least in the long term). In mycorrhizal associations, lichens and N2-fixing symbioses, it appears that well regulated bidirectional transport of nutrients between symbionts must occur, thus allowing a persistent compatible (and mutualistic) symbiosis. Evidence for such membrane modifications comes from changes in ATPase activity. The overall question to be considered in mutualistic symbioses is whether nutrient transfer processes have analogies elsewhere in the physiology of plants or whether 'new' transport events are switched on as a result of interactions between the organisms.

Tertiary nitrification in pilot-plant plug-flow fixed-film reactors with long-term ammonium deficiency

1994 ◽  
Vol 29 (10-11) ◽  
pp. 61-67 ◽  
Author(s):  
M. Fruhen ◽  
K. Böcker ◽  
S. Eidens ◽  
D. Haaf ◽  
M. Liebeskind ◽  
...  
Keyword(s):  
Pilot Plant ◽  
Effective Means ◽  
Plug Flow ◽  
Nitrification Rate ◽  
Industrial Project ◽  
Transfer Processes ◽  
Fixed Film ◽  
Film Reactor ◽  
Observation Period

The objective of this study is to investigate to what extent the nitrification capacity of a pilot-plant fixed-film reactor changes during extensive periods of nutrient supply deficiency. The examined pilot-plant was an upflow reactor filled with swelling clay of medium grain size (6 to 8 mm). The experiments revealed that the maximum nitrification rate remained practically constant during the first weeks after the onset of unregulated ammonium supply. The capacity declined slowly, dropping to approximately 66% of the initial capacity after about ten weeks. Still ammonium peaks of up to 8 mg/l were readily nitrified throughout the entire period of the experiment. The reduction in nitrification capacity during the observation period did not result from decay processes of biomass but from the reactor becoming blocked and thus hampering transfer processes. It could be observed that the detached organisms attached again further up. This semi-industrial project demonstrated that a plug-flow fixed-film reactor can be used as effective means of tertiary nitrification.

Cell wall metabolism during durian fruit dehiscence

2008 ◽  
Vol 48 (3) ◽  
pp. 391-401 ◽  
Author(s):  
L. Khurnpoon ◽  
J. Siriphanich ◽  
J.M. Labavitch
Keyword(s):  
Cell Wall ◽  
Cell Wall Metabolism ◽  
Fruit Dehiscence

Comparative ultrastructural analysis of mycorrhizal associations

1983 ◽  
Vol 61 (3) ◽  
pp. 917-943 ◽  
Author(s):  
Silvano Scannerini ◽  
Paola Bonfante-Fasolo
Keyword(s):  
Electron Microscopy ◽  
Surface Area ◽  
Ultrastructural Analysis ◽  
Nutrient Transfer ◽  
Cytological Feature ◽  
Symbiotic Interactions ◽  
Mycorrhizal Associations ◽  
Host Pathogen ◽  
Bacterial Associations ◽  
Functional Mechanisms

Electron microscopy is a powerful tool in understanding functional mechanisms in symbiosis (i.e., recognition and transfer of nutrients between partners), but mycorrhizal associations are not yet so well known as host–pathogen and host – mutualistic bacterial associations. However, the study of mycorrhizal ultrastructure has provided some interesting information. In fact unknown symbionts can be recognized with electron microscopy and mycorrhizae can be classified according to a sequence linking intercellular and intracellular interactions between host and fungus. General conclusions can be drawn from this ultrastructural sequence. (i) The most significant cytological feature in mycorrhizae is the presence of an interface through which partners communicate along a vast surface area. This is the key area for symbiotic interactions (both recognition and nutrient transfer) and can vary a great deal mostly in intracellular interactions. (ii) The ultracytochemical aspects of those interfaces, mostly as regards the components of the interfacial matrix, appear quite different from those of host–pathogen associations and suggest a compatibility mechanism. (iii) As regards the transfer of nutrients, even though it has been claimed that transfer of nutrient in all intracellular interactions is achieved by a digestion mechanism of the fungus by the host, available ultrastructural data are not consistent with this hypothesis.

scholarly journals Mecanismos de tolerancia a elementos potencialmente tóxicos en plantas

2017 ◽  
pp. 53 ◽  
Author(s):  
Daniel González-Mendoza ◽  
Omar Zapata-Pérez
Keyword(s):  
Heavy Metals ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Toxic Elements ◽  
Potentially Toxic Elements ◽  
Free Proline ◽  
Potentially Toxic Metals ◽  
Cellular Mechanisms ◽  
Mycorrhizal Associations ◽  
Broad Overview

Plants possess a wide array of potential cellular mechanisms that may be involved in the tolerance to potentially toxic elements. These mechanisms include mycorrhizal associations, heavy metals binding to cell wall, precipitation by extracellular exudates; reduction in uptake or efflux pumping of metals at the plasma membrane, chelation of metals in the cytosol by peptides such as phytochelatins, metallothionein, histidina free, proline free , and the compartmentation of metals in the vacuole by tono-plast- located transporters. This review provides a broad overview of the evidence of the involvement of each mechanism in plants' tolerance to potentially toxic metals.

scholarly journals Synergism of imipenem with fosfomycin associated with the active cell wall recycling and heteroresistance in Acinetobacter calcoaceticus-baumannii complex

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Uthaibhorn Singkham-in ◽  
Tanittha Chatsuwan
Keyword(s):  
Cell Wall ◽  
De Novo ◽  
Acinetobacter Calcoaceticus ◽  
Active Cell ◽  
Wild Type ◽  
Cell Wall Metabolism ◽  
Carbapenem Resistant ◽  
Type Form ◽  
Wild Type Form ◽  
Cell Wall Recycling

AbstractThe carbapenem-resistant Acinetobacter calcoaceticus-baumannii (ACB) complex has become an urgent threat worldwide. Here, we determined antibiotic combinations and the feasible synergistic mechanisms against three couples of ACB (A. baumannii (AB250 and A10), A. pittii (AP1 and AP23), and A. nosocomialis (AN4 and AN12)). Imipenem with fosfomycin, the most effective in the time-killing assay, exhibited synergism to all strains except AB250. MurA, a fosfomycin target encoding the first enzyme in the de novo cell wall synthesis, was observed with the wild-type form in all isolates. Fosfomycin did not upregulate murA, indicating the MurA-independent pathway (cell wall recycling) presenting in all strains. Fosfomycin more upregulated the recycling route in synergistic strain (A10) than non-synergistic strain (AB250). Imipenem in the combination dramatically downregulated the recycling route in A10 but not in AB250, demonstrating the additional effect of imipenem on the recycling route, possibly resulting in synergism by the agitation of cell wall metabolism. Moreover, heteroresistance to imipenem was observed in only AB250. Our results indicate that unexpected activity of imipenem on the active cell wall recycling concurrently with the presence of heteroresistance subpopulation to imipenem may lead to the synergism of imipenem and fosfomycin against the ACB isolates.

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