Change of resistance to lysozyme and ultrasonic disintegration of the mycelium of Streptomyces griseus under the influence of chelating agents and polyvalent cations

1968 ◽  
Vol 14 (7) ◽  
pp. 769-773 ◽  
Author(s):  
F. Szeszák ◽  
G. Szabó ◽  
J. Erdel ◽  
F. Müller
Keyword(s):  
Cell Wall ◽  
Life Cycle ◽  
Submerged Culture ◽  
Chelating Agents ◽  
Ethylenediaminetetraacetic Acid ◽  
Streptomyces Griseus ◽  
Enhanced Resistance ◽  
Polyvalent Cations

Mycelia of Streptomyces griseus strain No. 52-1 from a 2-day submerged culture pretreated with ethylenediaminetetraacetic acid (EDTA) were digested with lysozyme. The sensitivity of younger vegetative hyphae to lysozyme increased while that of older reproductive hyphae remained almost unchanged.EDTA or borate pretreatment increased resistance to ultrasonic disintegration in the case of 96-h mycelia from submerged culture. EDTA was most effective at a concentration of 10−5 M.The enhanced resistance to ultrasonic disintegration can be reversed by Mg2+ and Al3+ in a concentration of 10−5 M, while Ca2+ ions are ineffective.These results suggest the existence of a polyvalent-ion-dependent layer in the cell wall of streptomycetes. Such a layer would be exterior to the mucopeptide layer. Its thickness changes during the life cycle and it is most prominent in younger vegetative hyphae.

scholarly journals Upregulation of the Renin–Angiotensin System Pathways and SARS-CoV-2 Infection: The Rationale for the Administration of Zinc-Chelating Agents in COVID-19 Patients

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 506
Author(s):  
Loris Zamai
Keyword(s):  
Chelating Agents ◽  
Ethylenediaminetetraacetic Acid ◽  
Current Knowledge ◽  
Clinical Manifestations ◽  
Renin Angiotensin System ◽  
Experimental Models ◽  
Zinc Metalloprotease ◽  
Previous Hypothesis ◽  
Zinc Metalloproteases

The article describes the rationale for the administration of zinc-chelating agents in COVID-19 patients. In a previous work I have highlighted that the binding of the SARS-CoV spike proteins to the zinc-metalloprotease ACE2 has been shown to induce ACE2 shedding by activating the zinc-metalloprotease ADAM17, which ultimately leads to systemic upregulation of ACE2 activity. Moreover, based on experimental models, it was also shown the detrimental effect of the excessive systemic activity of ACE2 through its downstream pathways, which leads to “clinical” manifestations resembling COVID-19. In this regard, strong upregulation of circulating ACE2 activity was recently reported in COVID-19 patients, thus supporting the previous hypothesis that COVID-19 may derive from upregulation of ACE2 activity. Based on this, a reasonable hypothesis of using inhibitors that curb the upregulation of both ACE2 and ADAM17 zinc-metalloprotease activities and consequent positive feedback-loops (initially triggered by SARS-CoV-2 and subsequently sustained independently on viral trigger) is proposed as therapy for COVID-19. In particular, zinc-chelating agents such as citrate and ethylenediaminetetraacetic acid (EDTA) alone or in combination are expected to act in protecting from COVID-19 at different levels thanks to their both anticoagulant properties and inhibitory activity on zinc-metalloproteases. Several arguments are presented in support of this hypothesis and based on the current knowledge of both beneficial/harmful effects and cost/effectiveness, the use of chelating agents in the prevention and therapy of COVID-19 is proposed. In this regard, clinical trials (currently absent) employing citrate/EDTA in COVID-19 are urgently needed in order to shed more light on the efficacy of zinc chelators against SARS-CoV-2 infection in vivo.

Mobility of Chelated Radionuclides in Engineered Concrete Barriers

1992 ◽  
Vol 294 ◽  
Author(s):  
Craig A. Dicke ◽  
Robert W. Smith
Keyword(s):  
Citric Acid ◽  
Chelating Agents ◽  
Ethylenediaminetetraacetic Acid ◽  
Cobalt Complexes ◽  
Alkaline Ph ◽  
Pore Fluids ◽  
Concrete Barriers ◽  
Equilibrium Speciation ◽  
Low Level Radioactive Waste

ABSTRACTConcrete is a major component in many low-level radioactive waste (LLW) disposal facilities. The use of concrete is widespread because of its physical and structural properties and because it provides geochemical control on metal and radionuclide releases. Organic compounds are often disposed with radionuclides in LLW disposal facilities. Interactions between radionuclides and chelating agents must be evaluated to estimate mobility of radionuclides in concrete vaults. This paper quantifies the effects of two common organic components [citric acid and ethylenediaminetetraacetic acid (EDTA)] on radionuclide mobility in concrete barriers by using equilibrium geochemical calculations.Equilibrium speciation calculations indicate that some radionuclides are chelated in groundwater (pH 7) but are destabilized in the highly alkaline (pH 13) concrete pore fluids. Radionuclides complexed by EDTA and citrate are replaced by calcium in the concrete pore fluids. In addition, the citrate nuclide complex reacts to form uncomplexed citrate in concrete pore fluids. The chemical performance of concrete LLW disposal facilities should not be compromised by small amounts of chelating agents disposed with some radionuclides. However, EDTA may form significant nickel and cobalt complexes above the pH important in the long-term service life of concrete barriers.

scholarly journals Secretion of Cryparin, a Fungal Hydrophobin

1999 ◽  
Vol 65 (12) ◽  
pp. 5431-5435 ◽  
Author(s):  
Patricia M. McCabe ◽  
Neal K. Van Alfen
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Submerged Culture ◽  
Secretory Pathway ◽  
Culture Medium ◽  
Secretory Vesicle ◽  
Cryphonectria Parasitica ◽  
Secreted Protein ◽  
Filamentous Ascomycete ◽  
A Cell

ABSTRACT Cryparin is a cell-surface-associated hydrophobin of the filamentous ascomycete Cryphonectria parasitica. This protein contains a signal peptide that directs it to the vesicle-mediated secretory pathway. We detected a glycosylated form of cryparin in a secretory vesicle fraction, but secreted forms of this protein are not glycosylated. This glycosylation occurred in the proprotein region, which is cleaved during maturation by a Kex2-like serine protease, leaving a mature form of cryparin that could be isolated from both the cell wall and culture medium. Pulse-chase labeling experiments showed that cryparin was secreted through the cell wall, without being bound, into the culture medium. The secreted protein then binds to the cell walls ofC. parasitica, where it remains. Binding of cryparin to the cell wall occurred in submerged culture, presumably because of the lectin-like properties unique to this hydrophobin. Thus, the binding of this hydrophobin to the cell wall is different from that of other hydrophobins which are reported to require a hydrophobic-hydrophilic interface for assembly.

scholarly journals Pathobiology ofPneumocystispneumonia: life cycle, cell wall and cell signal transduction

2015 ◽  
Vol 15 (6) ◽  
pp. fov046 ◽  
Author(s):  
Joseph H. Skalski ◽  
Theodore J. Kottom ◽  
Andrew H. Limper
Keyword(s):  
Signal Transduction ◽  
Cell Wall ◽  
Life Cycle ◽  
Cell Signal ◽  
Cell Signal Transduction

scholarly journals Affinity, life cycle, and intracellular complexity of organic-walled microfossils from the Mesoproterozoic of Shanxi, China

2015 ◽  
Vol 89 (1) ◽  
pp. 28-50 ◽  
Author(s):  
Heda Agić ◽  
Małgorzata Moczydłowska ◽  
Lei-Ming Yin
Keyword(s):  
Cell Wall ◽  
Life Cycle ◽  
Structural Complexity ◽  
Protective Role ◽  
Life Cycles ◽  
Wall Structure ◽  
Phenotypic Characters ◽  
Biological Affinity ◽  
New Material ◽  
A Cell

AbstractLight microscope and scanning electron microscope observations on new material of unicellular microfossilsDictyosphaera macroreticulataandShuiyousphaeridium macroreticulatum,from the Mesoproterozoic Ruyang Group in China, provide insights into the microorganisms’ biological affinity, life cycle and cellular complexity.Gigantosphaeridium fibratumn. gen. et sp., is described and is one of the largest Mesoproterozoic microfossils recorded. Phenotypic characters of vesicle ornamentation and excystment structures, properties of resistance and cell wall structure inDictyosphaeraandShuiyousphaeridiumare all diagnostic of microalgal cysts. The wide size ranges of the various morphotypes indicate growth phases compatible with the development of reproductive cysts. Conspecific biologically, each morphotype represents an asexual (resting cyst) or sexual (zygotic cyst) stage in the life cycle, respectively. We reconstruct this hypothetical life cycle and infer that the organism demonstrates a reproductive strategy of alternation of heteromorphic generations. Similarly inGigantosphaeridium,a metabolically expensive vesicle with processes suggests its protective role as a zygotic cyst. In combination with all these characters and from the resemblance to extant green algae, we propose the placement of these ancient microorganisms in the stem group of Chloroplastida (Viridiplantae). A cell wall composed of primary and secondary layers inDictyosphaeraandShuiyouisphaeridiumrequired a high cellular complexity for their synthesis and the presence of an endomembrane system and the Golgi apparatus. The plastid was also present, accepting the organism was photosynthetic. The biota reveals a high degree of morphological and cell structural complexity, and provides an insight into ongoing eukaryotic evolution and the development of complex life cycles with sexual reproduction by 1200 Ma.

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