Antibiotic Y: biosynthesis by Fusarium avenaceum (Corda ex Fries) Sacc., isolation, and some physicochemical and biological properties.

A compound very similar to the mycotoxin citrinin was observed on thin-layer chromatographic plates during the screening analysis of grain extracts. This compound was produced by 22 of the tested Fusarium avenaceum (Corda ex Fries) Sacc. strains isolated from wheat, triticale, barley, corn, and potatoes. A chemical test confirmed the presence of an unknown compound, which was given the preliminary name of antibiotic Y (indicating yellow fluorescence). The following properties of the new metabolite are described: spectroscopic (UV, infrared, proton nuclear magnetic resonance, fluorescence, and mass spectrometry), phytotoxic, antibiotic (inhibitory effect of bacterial growth), and toxic (toxicity to Artemia salina, chicken embryos, and mouse fibroblasts). Elemental analysis of the compound showed that it had the general formula C15H10O8, in agreement with the mass spectrometric finding that the molecular ion had a molecular weight of 318. The structure of the compound is presently under study.     

Formation of Avenacein Y by Fusarium avenaceum Fries Sacc. isolates from Germany and pathogenicity of the isolates to cereal seedlings

Twelve isolates ofFusarium avenaceum Fries Sacc. originating from diseased corn plants from Germany produced Avenacein Y in amounts ranging from 0.001 to 1.6 g/kg of wheat grain. The isolates proved most pathogenic to triticale seedlings, less pathogenic to rye seedlings and least to wheat. Pathogenicity of the isolates was not correlated with their ability to produce Avenacein Y.     

Modelling inactivation by aqueous chlorine dioxide of Dothiorella gregaria Sacc. and Fusarium tricinctum (Corda) Sacc. spores inoculated on fresh chestnut kernel

Aims: To model survival curves of Dothiorella gregaria Sacc. and Fusarium tricinctum (Corda) Sacc. spores inoculated on fresh chestnut kernel exposed to aqueous chlorine dioxide (ClO₂). Methods and Results: Spores of two dominant spoilage fungi, D. gregaria and F. tricinctum, were inoculated onto chestnut kernel and treated with ClO₂. The inactivation efficacy of ClO₂ treatment increased with ClO₂ concentration and treatment time. The Weibull model was the best model to describe the ClO₂ survival curves of D. gregaria, while the modified Gompertz model was most appropriate for fitting the survival curves of F. tricinctum. Within the range of ClO₂ concentration from 3 to 7 mg l^?1, the n values in the Weibull model were similar. The b value in the Weibull model and decimal logarithms of the M, B and C values in the modified Gompertz model had linear relationships with ClO₂ concentration. After simplification, these two models still provided acceptable predictions. Conclusion: Applying models for describing survival curves of fungal spores on chestnut kernel by aqueous ClO₂ was feasible. Significance and Impact of the Study: This work would promote the application of ClO₂ sanitizing technique and mathematical models when preventing the occurrence of chestnut kernel decay.     

Formation of Avenacein Y by<Emphasis Type="Italic">Fusarium avenaceum</Emphasis> Fries Sacc. isolates from poland and biological properties of the compound

Eighteen isolates ofFusarium avenaceum Fries Sacc. originating from cereals, potato and carrot from Poland synthesized Avenacein Y in amounts ranging from 0.01 to 2.0 g/kg of wheat grain. The compound was produced in 1 kg of corn kernels by isolate KF-58, isolated, identified and used to test for antibiotic activity against plant pathogenic fungi of 11 genera. Application of Avenacein Y caused slight decrease of mycelium growth in four species only.     

Canker on culm of Bambusa multiplex (Lour.) Raeusch. ex Schult. caused by Fusarium incarnatum (Roberge) Sacc.

Bambusa multiplex has been broadly cultivated in China and has significant economical, ecological and ornamental importance. A canker on the culm of B. multiplex was first time discovered in 2015 in Shanghai, China. In this study, the fungal isolate XSZ‐1 isolated from the infected tissues was determined to be a pathogen of canker on the culm of B. multiplex by fulfilling Koch's postulates. The fungal pathogen was identified as Fusarium incarnatum based on the morphological characteristics and phylogenetic analyses with the sequences of ITS, TEF‐1α and RPB2. To our knowledge, this is the first report of a canker on the culm of B. multiplex caused by F. incarnatum worldwide.     

2,3,5-Tris-ethylenimino-1,4-benzoquinone (Trenimon): some chemical and biological properties

The three aziridine rings of 2,3,5-tris-ethylenimino-1,4-benzoquinone (Trenimon) were found to be active alkylating centres in the presence of acid catalyst, but differed in reactivity among themselves. At a given pH Trenimon was readily reduced by a number of agents including cysteine, which probably formed a substitution derivative. The cysteine derivative possessed three alkylating groups which were more reactive than those of pure Trenimon. Trenimon was soluble in fat solvents but the reduction and substitution derivatives were not. Trenimon was bound to hemoglobin and to albumins, probably by a substitution reaction between a sulfhydryl group of the protein and the 6-carbon atom of the drug. Binding to globulin occurred only following reduction of the protein. Trenimon was readily taken up by L5178Y lymphoma cells in suspension culture and was highly toxic but the cysteine derivative was not readily taken up and was less toxic than Trenimon by three orders of magnitude. The implications of the solubility and other physical properties of the alkylating agents are discussed, and evidence is presented that the biologically effective concentration of a drug is that which binds to the cell surface.     

Taste attractiveness of free amino acids and their physicochemical and biological properties (as exemplified by fishes)

Using fishes (32 species, 11 families) as an example, the relationship between the taste attractiveness of free amino acids (L-isomers) and their physicochemical and biological properties was analyzed. It was shown that essential amino acids, most nutritionally required for an organism, have lower taste attractiveness for fishes than nonessential amino acids. Only in 6 of the 32 tested species (sunbleak Leucaspius delineatus, European minnow Phoxinus phoxinus, dace Leuciscus leuciscus, chub Leuciscus cephalus, blue gourami Trichopodus trichopterus, pearl gourami Trichopodus leerii) the relationship between the taste attractiveness and molecular weight of amino acids was supported statistically, being negative in all cases. Only in 2 species, a statistically significant correlation between the taste properties of amino acids and the dissociation constant (K₁) was found, positive in the stone loach Barbatula barbatula and negative in the lake char Salvelinus namaycush. A positive correlation between taste preferences and the magnitude of the isoelectric point (pI) of amino acids was found in one species (roach Rutilus rutilus) and a negative correlation in 2 species (brown trout Salmo trutta and Arctic char Salvelinus alpinus erythrinus). A statistically significant correlation between the taste attractiveness and water solubility of amino acids was revealed in 2 species (chum salmon Oncorhynchus keta and navaga Eleginus nawaga), negative in both cases. The flavor, which stimulates food intake, was found to be more often intrinsic to acidic and polar uncharged than basic and nonpolar amino acids, L- than D-isomers, amino acids with an amino group at the α- than β-position. Amino acids are more attractive than their salts. Aromatic amino acids are much less attractive than S-containing or acyclic amino acids. Thus, in most fish species there is no or weak relationship between the taste attractiveness of free amino acids and many of their physical, chemical and biological properties, suggesting a mediated character of this relationship and/or its poor detectability.     

Glycopolymer modification on physicochemical and biological properties of poly(L-lysine) for gene delivery

Poly(L-lysine) (PLL) has excellent plasmid DNA (pDNA) condensation capacity. However, the relatively high cytotoxicity and low transfection efficiency limit its application as gene delivery vectors. Here, well-defined glycopolymers are synthesized by reversible addition fragmentation transfer polymerization and grafted onto PLL to improve the gene delivery performance. After glycopolymer modification, PLL shows reduced cytotoxicity. By regulating the glycopolymer length and amino group substitution degree, the glycopolymer modified PLL can condense pDNA with proper strength, protect the condensed pDNA from degradation and release them in time. Transfection with NIH3T3 and HepG2 cells shows that the glycopolymer modified PLL has improved transfection efficiencies. The low cytotoxicity, effective pDNA protection and enhanced transfection efficiencies indicate that glycopolymer modification would be an effective strategy to improve the polycation properties for gene delivery.     

A new plasminogen activator isolated from the saliva of Rhapactor biparticeps (Heteroptera, Reduviidae): biological and physicochemical properties

A new plasminogen activator has been isolated from the saliva of Rhapactor biparticeps. This product is 5% of salivary proteins and acts at an optimal pH of 7.8.P.D.F which results from its action on human fibrinogen are similar to those which are obtained with streptokinase. The modalities of action of this plasminogen activator on the fibrinogen are discussed.     

Antibiotic discovery: combining isolation chip (iChip) technology and co-culture technique

Applied Microbiology and Biotechnology - Antibiotics had been a useful tool for treating bacterial infections since their discovery, but with the passage of time, the evolution of resistance among...     

Depolymerization of a hydroxy fatty acid biopolymer, cutin, by an extracellular enzyme from Fusarium solani f. pisi: isolation and some properties of the enzyme

Fusarium solani f. pisi was shown to grow on the hydroxy fatty acid biopolymer cutin as the sole carbon source. Such growth conditions induced the production of an extracellular cutin depolymerising enzyme. Analysis of products enzymatically derived from labeled cutin by thin-layer chromatography and radio gas-liquid chromatography showed that the Fusarium enzyme released all classes of cutin monomers. This enzyme preparation also catalyzed hydrolysis of several model ester substrates. It did not hydrolyze triacyl glycerol and pancreatic lipase did not hydrolyze cutin, indicating that the Fusarium enzyme is not a nonspecific lipase. With p-nitrophenyl palmitate as the model substrate the enzyme showed a broad pH optimum near 8.5 and it was stimulated by Triton X-100. Maximal stimulation was obtained at 3.7 mg/ ml of the detergent. Apparent K_m for p-nitrophenyl palmitate was 1.6 × 10^?4m. p-Nitrophenyl esters of C₂–C₁₈ acids gave comparable values for K_m and V revealing no striking specificity. Treatment with diisopropyl fluorophosphate severely inhibited the enzyme while iodoacetamide and p-chloromercuric benzoate did not affect the enzymatic activity, suggesting that the Fusarium enzyme is a serine hydrolase.     

The synthesis and some biological properties of N-(6-purinyl)peptides

The chemical synthesis and biological properties of N-(6-purinyl)peptides are described. N-(6-Purinyl)amino-acid derivatives were synthesized and condensed with amino acid esters and peptide esters using the dicyclohexylcarbodiimide/N-hydroxysuccinimide method. The products were isolated via gel filtration on Sephadex G-10 in 0.05M NH4HCO3 followed by either ion exchange chromatography on SP-Sephadex or by preparative HPLC. The methyl esters were saponified and the tert-butyl ester group was removed by treatment with trifluoroacetic acid without damaging the purinyl residue. N-(6-Purinyl)peptides were characterised by chromatographic and spectroscopic methods. Acid hydrolysis of N-(6-purinyl)-L-amino acids caused the racemization of the neighbouring L-amino acid. Model studies were performed with N-(6-purinyl)-L-alanine, N-(6-purinyl)-D-alanine, N-(6-purinyl)-L-alanyl-L-leucine and N-(6-purinyl)-D-alanyl-L-leucine. After acid hydrolysis the N-(6-purinyl)amino acids were totally racemized and the N-(6-purinyl)dipeptides formed 14% of the enantiomer of alanine. The N-(6-purinyl)-omega-amino acids and the N-(6-purinyl)peptides were screened in a limited number of tests as immunomodulators (antibody-secretion, phagocytosis, cytostatic activity of macrophages) and as cytotoxic agents.     

Short cationic lipopeptides as effective antibacterial agents: Design,physicochemical properties and biological evaluation

The spread of drug-resistant bacteria has imparted a sense of urgency in the search for new antibiotics. In an effort to develop a new generation of antibacterial agents, we have designed de novo charged lipopeptides inspired by natural antimicrobial peptides. These short lipopeptides are composed of cationic lysine and hydrophobic lipoamino acids that replicate the amphiphilic properties of natural antimicrobial peptides. The resultant lipopeptides were found to self-assemble into nanoparticles. Some were effective against a variety of Gram-positive bacteria, including strains resistant to methicillin, daptomycin and/or vancomycin. The lipopeptides were not toxic to human kidney and liver cell lines and were highly resistant to tryptic degradation. Transmission electron microscopy analysis of bacteria cells treated with lipopeptide showed membrane-damage and lysis with extrusion of cytosolic contents. With such properties in mind, these lipopeptides have the potential to be developed as new antibacterial agents against drug-resistant Gram-positive bacteria.     

The isolation and some properties of a lectin (Haemagglutinin) from Cucurbita phloem exudate

The occurrence of high haemagglutinating (lectin) activity in phloem exudate from three cucurbit species is reported. The protein responsible for this lectin activity in Cucurbita maxima Duch. has been isolated by cation exchange chromatography on Sepharose and identified by gel electrophoresis. The lectin showed agglutinating activity at concentrations as low as 0.1 g/ml. No sugar, including those transported in the phloem of these species, interacted with agglutination. The lectin could not be extracted from cucurbit seed, but appeared in 5-day old seedlings. The possible role of a lectin in the sieve element is discussed.