scholarly journals Formulation and Safety Tests of a Wickerhamomyces anomalus–Based Product: Potential Use of Killer Toxins of a Mosquito Symbiotic Yeast to Limit Malaria Transmission

Toxins ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 676
Author(s):  
Alessia Cappelli ◽  
Consuelo Amantini ◽  
Federica Maggi ◽  
Guido Favia ◽  
Irene Ricci
Keyword(s):  
Freeze Drying ◽  
Room Temperature ◽  
Killer Toxin ◽  
Symbiotic Association ◽  
Proinflammatory Response ◽  
Anopheles Mosquitoes ◽  
Wickerhamomyces Anomalus ◽  
Killer Toxins ◽  
Stable Product ◽  
Potential Use

Wickerhamomyces anomalus strain WaF17.12 is a yeast with an antiplasmodial property based on the production of a killer toxin. For its symbiotic association with Anopheles mosquitoes, it has been proposed for the control of malaria. In an applied view, we evaluated the yeast formulation by freeze-drying WaF17.12. The study was carried out by comparing yeast preparations stored at room temperature for different periods, demonstrating that lyophilization is a useful method to obtain a stable product in terms of cell growth reactivation and maintenance of the killer toxin antimicrobial activity. Moreover, cytotoxic assays on human cells were performed, showing no effects on the cell viability and the proinflammatory response. The post-formulation effectiveness of the killer toxin and the safety tests indicate that WaF17.12 is a promising bioreagent able to impair the malaria parasite in vector mosquitoes.

The killer yeast Wickerhamomyces anomalus Cf20 exerts a broad anti-Candida activity through the production of killer toxins and volatile compounds

2020 ◽  
Vol 58 (8) ◽  
pp. 1102-1113 ◽  
Author(s):  
Miguel Fernández de Ullivarri ◽  
Gabriela A Bulacios ◽  
Silvia A Navarro ◽  
Lucía Lanza ◽  
Lucia M Mendoza ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Volatile Compounds ◽  
Opportunistic Infections ◽  
Killer Toxin ◽  
Fungal Growth ◽  
Candida Spp ◽  
Killer Yeast ◽  
Wickerhamomyces Anomalus ◽  
Fungistatic Activity ◽  
Killer Toxins

Abstract Candidiasis is a group of opportunistic infections caused by yeast of the genus Candida. The appearance of drug resistance and the adverse effects of current antifungal therapies require the search for new, more efficient therapeutic alternatives. Killer yeasts have aroused as suitable candidates for mining new antifungal compounds. Killer strains secrete antimicrobial proteins named killer toxins, with promissory antifungal activity. Here we found that the killer yeast Wickerhamomyces anomalus Cf20 and its cell-free supernatant (CFS) inhibited six pathogenic strains and one collection strain of Candida spp. The inhibition is mainly mediated by secreted killer toxins and, to a lesser extent, by volatile compounds such as acetic acid and ethyl acetate. A new large killer toxin (>180 kDa) was purified, which exerted 70–74% of the total CFS anti-Candida activity, and the previously described glucanase KTCf20 was inhibitory in a lesser extent as well. In addition, we demonstrated that Cf20 possesses the genes encoding for the β-1,3-glucanases WaExg1 and WaExg2, proteins with extensively studied antifungal activity, particularly WaExg2. Finally, the 10-fold concentrated CFS exerted a high candidacidal effect at 37°C, completely inhibiting the fungal growth, although the nonconcentrated CFS (RCF 1) had very limited fungistatic activity at this temperature. In conclusion, W. anomalus Cf20 produces different low and high molecular weight compounds with anti-Candida activity that could be used to design new therapies for candidiasis and as a source for novel antimicrobial compounds as well.

scholarly journals A new report on gene expression of three killer toxin genes with antimicrobial activity of two killer toxins in Iraq

2020 ◽  
Vol 44 (1) ◽  
Author(s):  
Najwa Mohammed Jameel Ali Abu-Mejdad ◽  
Adnan I. Al-Badran ◽  
Abdullah H. Al-Saadoon ◽  
Mohammed Hussein Minati
Keyword(s):  
Gene Expression ◽  
Extracellular Enzymes ◽  
Killer Toxin ◽  
Bacterial Strains ◽  
Ascomycetous Yeast ◽  
Torulaspora Delbrueckii ◽  
Wickerhamomyces Anomalus ◽  
Toxin Genes ◽  
Killer Toxins ◽  
Type Strains

Abstract Background The K1, K2, and K28 toxins are usually encoded by several cytoplasmically genetic satellite dsRNAs (M1, M2, and M28), which are encapsulated with virus-like particles (VLPs) and reliant on an additional assembly of assistant yeast viruses (L-A) for their reproduction and encapsidation. Ascomycetous yeast species that have these VLPs are especially attractive targets for finding killer toxins like proteins. This is because the organisms are known in producing a large variety of secondary metabolites and extracellular enzymes, which have medical importance as alternative drugs for resistance bacterial strains, particularly multi-resistance drugs (MRD). Results For the first time, 31 type strains of yeasts were tested for killer toxin production in Iraq via the measurement of gene expression of three killer toxin genes (M1, M2, and M28) within the mycovirus in yeasts. All the type strains gave an expression for the three killer toxins with variable levels. The highest expression was recorded for the killer toxin genes in Torulaspora delbrueckii followed by Wickerhamomyces anomalus. Determined antibacterial activity of two killer toxins appeared with high inhibition zone against pathogenic strains of bacteria. Cytotoxicity against human blood cells was not found. These results considered the first record of killer toxins isolated from type strains in Iraq. Conclusion The two typical strains Torulaspora delbrueckii and Wickerhamomyces anomalus showed the highest level of gene expression for the three killer toxins.

Scanning Electron Microscopy-cuticular Lesions on the Roundworm Ascaris Suum

1970 ◽  
Vol 28 ◽  
pp. 114-115
Author(s):  
P. A. Madden ◽  
W. R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Freeze Drying ◽  
Room Temperature ◽  
Secondary Electron ◽  
Distilled Water ◽  
Freeze Dried ◽  
Silver Paint ◽  
To Come ◽  
Scanning Electron

The intestinal roundworm of swine is pinkish in color and about the diameter of a lead pencil. Adult worms, taken from parasitized swine, frequently were observed with macroscopic lesions on their cuticule. Those possessing such lesions were rinsed in distilled water, and cylindrical segments of the affected areas were removed. Some of the segments were fixed in buffered formalin before freeze-drying; others were freeze-dried immediately. Initially, specimens were quenched in liquid freon followed by immersion in liquid nitrogen. They were then placed in ampuoles in a freezer at −45C and sublimated by vacuum until dry. After the specimens appeared dry, the freezer was allowed to come to room temperature slowly while the vacuum was maintained. The dried specimens were attached to metal pegs with conductive silver paint and placed in a vacuum evaporator on a rotating tilting stage. They were then coated by evaporating an alloy of 20% palladium and 80% gold to a thickness of approximately 300 A°. The specimens were examined by secondary electron emmission in a scanning electron microscope.

High-Resolution Scanning Electron Microscopy of Biological Specimens

1988 ◽  
Vol 46 ◽  
pp. 186-187
Author(s):  
M. Müller ◽  
R. Hermann
Keyword(s):  
High Resolution ◽  
Freeze Drying ◽  
Room Temperature ◽  
Structural Information ◽  
Freeze Substitution ◽  
Critical Point Drying ◽  
Sem Study ◽  
Major Factors ◽  
Structural Preservation ◽  
Preparation Techniques

Three major factors must be concomitantly assessed in order to extract relevant structural information from the surface of biological material at high resolution (2-3nm).Procedures based on chemical fixation and dehydration in graded solvent series seem inappropriate when aiming for TEM-like resolution. Cells inevitably shrink up to 30-70% of their initial volume during gehydration; important surface components e.g. glycoproteins may be lost. These problems may be circumvented by preparation techniques based on cryofixation. Freezedrying and freeze-substitution followed by critical point drying yields improved structural preservation in TEM. An appropriate preservation of dimensional integrity may be achieved by freeze-drying at - 85° C. The sample shrinks and may partially collapse as it is warmed to room temperature for subsequent SEM study. Observations at low temperatures are therefore a necessary prerequisite for high fidelity SEM. Compromises however have been unavoidable up until now. Aldehyde prefixation is frequently needed prior to freeze drying, rendering the sample resistant to treatment with distilled water.

Investigations on the Nature of Hemophilia A

1963 ◽  
Vol 09 (01) ◽  
pp. 030-052 ◽  
Author(s):  
Eberhard Mammen
Keyword(s):  
Factor Viii ◽  
Human Plasma ◽  
Barium Sulfate ◽  
Freeze Drying ◽  
Room Temperature ◽  
Hemophilia A ◽  
Normal Human Plasma ◽  
Normal Human ◽  
And Storage ◽  
Prothrombin Activation

SummaryIn this paper an inhibitor is described that is found in hemophilic plasma and serum different from any till now described inhibitor. The inhibitor only inhibits prothrombin activation in the “intrinsic clotting systems”. This inhibitor is probably not present in normal human plasma or serum. It is destroyed by ether and freeze drying, is labile to acid and storage at room temperature. It is stable upon dialysis and has not been adsorbed on barium sulfate, aluminum hydroxide or kaolin. It precipitates at 50% v/v saturation with alcohol. The nature of this inhibitor seems to be a protein or lipoprotein.Factor VIII was isolated from hemophilic plasma. The amount isolated was the same as from normal plasma and the activity properties were not different. Hemophiliacs have normal amounts of factor VIII.

Killer toxin of Pichia membranifaciens and its possible use as a biocontrol agent against grey mould disease of grapevine

Microbiology ◽  
2004 ◽  
Vol 150 (8) ◽  
pp. 2527-2534 ◽  
Author(s):  
A. Santos ◽  
D. Marquina
Keyword(s):  
Killer Toxin ◽  
Grey Mould ◽  
Toxin Production ◽  
Killer Activity ◽  
Pichia Membranifaciens ◽  
Sds Page ◽  
Toxin Protein ◽  
Killing Action ◽  
Killer Protein ◽  
Potential Use

The use of Pichia membranifaciens CYC 1106 killer toxin against Botrytis cinerea was investigated. This strain exerted a broad-specificity killing action against other yeasts and fungi. At pH 4, optimal killer activity was observed at temperatures up to 20 °C. At 25 °C the toxic effect was reduced to 70 %. The killer activity was higher in acidic medium. Above about pH 4·5 activity decreased sharply and was barely noticeable at pH 6. The killer toxin protein from P. membranifaciens CYC 1106 was purified to electrophoretic homogeneity. SDS-PAGE of the purified killer protein indicated an apparent molecular mass of 18 kDa. Killer toxin production was stimulated in the presence of non-ionic detergents. The toxin concentrations present in the supernatant during optimal production conditions exerted a fungicidal effect on a strain of B. cinerea. The symptoms of infection and grey mould observed in Vitis vinifera plants treated with B. cinerea were prevented in the presence of purified P. membranifaciens killer toxin. The results obtained suggest that P. membranifaciens CYC 1106 killer toxin is of potential use in the biocontrol of B. cinerea.

Room-temperature-storable chemiluminescence freeze-drying mixes for detection of SARS-CoV-2 neutralizing antibody

2021 ◽  
pp. 1-8
Author(s):  
Qihan Zhang ◽  
Liuyu Gong ◽  
Yewei Zhang ◽  
Ya Shen ◽  
Lin Shen ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Room Temperature ◽  
Neutralizing Antibody

scholarly journals Effect of Olive-Pine Bottom Ash on Properties of Geopolymers Based on Metakaolin

2019 ◽  
Author(s):  
Eduardo Bonet-Martínez ◽  
Pedro García-Cobo ◽  
Luis Pérez-Villarejo ◽  
Eulogio Castro ◽  
Dolores Eliche-Quesada
Keyword(s):  
Room Temperature ◽  
Bottom Ash ◽  
Raw Material ◽  
Climatic Chamber ◽  
General Terms ◽  
Saturated Atmosphere ◽  
Naoh Solution ◽  
Alkaline Activator ◽  
Water Saturated ◽  
Potential Use

In this research, the feasibility of using bottom ashes generated by the combustion of biomass (olive pruning and pine pruning) as a source of aluminosilicates (OPBA) has been studied, replacing the metakaolin precursor (MK) in different proportions (0, 25, 50, 75 and 100 wt. % substitution) for the synthesis of geopolymers. As alkaline activator an 8 M NaOH solution and a Na2SiO3 have been used. The geopolymers were cured 24 hours in a climatic chamber at 60 ° C in a water-saturated atmosphere, subsequently demoulded and cured at room temperature for 28 days. The results indicated that the incorporation of OPBA waste, which have 19.7 wt. % of Ca, modifies the characteristics of the products formed after alkaline activation. In general terms, the incorporation of increasing amounts of calcium-rich ashes results in geopolymers with higher bulk density. The compressive strength increases with the addition of up to 50 wt. % of OPBA with respect to the control geopolymers, contributing the composition of the residue to the acquisition of a better behaviour mechanical. The results indicate the potential use of these OPBA waste as raw material to produce unconventional cements with 28-day curing strengths greater than 10 MPa, and thermal conductivities less than 0.35 W/mK.

scholarly journals Isolation of a Bimetallic Cobalt(III) Nitride and Examination of its Hydrogen Atom Abstraction Chemistry and Reactivity Towards H2

2020 ◽  
Author(s):  
Debabrata Sengupta ◽  
Christian Sandoval-Pauker ◽  
Emily Schueller ◽  
Angela M. Encerrado-Manriquez ◽  
Alejandro J. Metta-Magaña ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Atom Abstraction ◽  
Functional Theory ◽  
Kinetic Rate ◽  
Rate Analysis ◽  
Stable Product ◽  
Activation Pathways ◽  
Computational Analyses

Room temperature photolysis of the bis(azide)cobaltate(II) complex [Na(THF)<sub>x</sub>][(<sup>ket</sup>guan)Co(N3)2] (<sup>ket</sup>guan = [(tBu2CN)C(NDipp)2]–, Dipp = 2,6-diisopropylphenyl) (3a) in THF cleanly forms the binuclear cobalt nitride [Na(THF)4{[(<sup>ket</sup>guan)Co(N3)]2(μ-N)}]<sub>n</sub> (1). Compound 1 represents the first example of an isolable, bimetallic cobalt nitride complex, and it has been fully characterized by spectroscopic, magnetic, and computational analyses. Density functional theory supports a CoIII=N=CoIII canonical form with significant π-bonding between the cobalt centers and the nitride atom. Unlike other Group 9 bridging nitride complexes, no radical character is detected at the bridging N-atom of 1. Indeed, 1 is unreactive towards weak C-H donors and even co-crystallizes with a molecule of cyclohexadiene (CHD) in its crystallographic unit cell to give 1·CHD as a room temperature stable product. Notably, addition of pyridine to 1 or photolyzed solutions of [(<sup>ket</sup>guan)Co(N3)(py)]<sub>2</sub> (4a) leads to destabilization via activation of the nitride unit, resulting in the mixed-valent Co(II)/(III) bridged imido species [(<sup>ket</sup>guan)Co]2(μ-NH)(μ-N3) (5) formed from intermolecular hydrogen atom abstraction (HAA) of strong C-H bonds (BDE ~ 100 kcal/mol). Kinetic rate analysis of the formation of 5 in the presence of C6H12 or C6D12 gives a KIE = 2.5±0.1, supportive of a HAA formation path-way. The reactivity of our system was further probed by photolyzing C6D6/py-d5 solutions of 4a under an H2 atmosphere (150 psi), which leads to the exclusive formation of the bis(imido)[(<sup>ket</sup>guan)Co(μ-NH)]2 (6) as a result of dihydrogen activa-tion. These results provide unique insights into the chemistry and electronic structure of late 3d-metal nitrides while providing entryway into C-H activation pathways.

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