Studies on Metabolites of Alternaria kikuchiana Tanaka,a Phytopathogenic Fungus of Japanese Pear

The structure of a metabolite, C₁₀H₁₀O₅ (I), obtained as a weakly toxic substance from the culture filtrate of Alternaria kikuchiana, was determined as 3,6,8-trihydroxy-3-methyl-3,4- dihydroisocoumarin (Ia). Though three tautomeric forms—lactol form (Ia), keto form (Ib) and enol form (Ic) were possible for (I), it was found that the compound (I) existed as the lactol form (Ia) both in a crystalline state and in acetone, chloroform and methanol solutions. This metabolite gave weak necrotic symptom to pear leaves, but stimulated the root elongation of rice and radish seedlings (ca. 20~30%) at 5 ppm and also showed synergistic activity with gibberellin A₃ on the stem elongation of rice seedlings (ca. 30%).     

百日草链格孢菌粗毒素的生产、提取及稳定性的研究

百日草链格孢菌是从世界性恶性杂草苍耳罹病植株上分离得到的植物病原真菌,研究表明该菌对紫茎泽兰有致病作用,可产生致病的次生代谢产物--毒素。本文对该菌的次生代谢产毒能力情况进行了研究。对培养基条件进行了筛选,确定了有利于该菌产毒的温度为25℃、pH值为6.5、培养时间为9～12天、足够的黑暗以及溶氧、转速等培养条件。利用大规模发酵与发酵产物后提取工艺获取粗毒素并通过分析贮存时间、温度、光照对粗毒素稳定性的影响表明具有开发天然微生物源除草剂的潜力。     

百日草链格孢菌毒素对加拿大一枝黄花叶片伤害的生理生化研究

采用植物抗性生理和光合生理的分析测定技术,研究了分离自罹病苍耳植株上的百日草链格孢菌产生的毒素对加拿大一枝黄花叶组织细胞膜透性、丙二醛(M DA)含量、光合能力以及过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)和过氧化氢酶(CAT)活性的影响.结果表明,百日草链格孢菌毒素使加拿大一枝黄花叶组织细胞膜透性上升,膜脂过氧化加强,M DA含量上升;叶片的POD、APX和CAT的活性均较对照降低,其光合作用明显地受到抑制.说明百日草链格孢菌毒素具有防除加拿大一枝黄花的潜力.     

Isolation and characterization of non-labeled and 13C-labeled mannans from Pichia pastoris yeast

Mannans from genetically modified Pichia pastoris yeast, used for overproduction of neural cell adhesion molecule protein, grown on normal media or on uniformly 13C-labeled glucose and methanol, were isolated and characterized by high-field (750 MHz) NMR spectroscopy. Fully 13C-labeled oligosaccharide fragments were prepared from mannans by acetolysis. According to the data obtained, the mannan is made up of a main chain of alpha-(1-->6)-linked mannopyranosyl residues, substituted at 0-2 with alpha-mannopyranosyl or a alpha-D-Manp-(1-->2)-beta-D-Manp-(1-->2)-beta-D-Manp-( 1-->2)-alpha-D-Manp- group, and with much lower content of substitution with beta-D-Manp-(1-->2)-alpha-D-Manp-. A fraction of these oligosaccharide side chains is again substituted with alpha-D-Glcp or alpha-D-GlcpNAc through a phosphodiester linkage to the 6 position of the first mannopyranosyl residue. Improved conditions of acetolysis, cleaving all alpha-(1-->6) linkages, but not beta-mannoside linkages, are proposed.     

Isolation and characterization of microsatellite markers from the phytopathogenic fungus Alternaria dauci

Eleven polymorphic microsatellite markers were isolated from the necrotrophic phytopathogenic fungus Alternaria dauci based on enriched genomic libraries. In order to assess allelic variability, the microsatellite loci were analysed in a collection of 43 isolates. The number of detected alleles in 11 loci ranged from two to 24 (mean 10.4). Test of cross-species amplification and sequencing of the resulting amplicons showed that some of these microsatellites could be used in different species such as Alternaria solani, Alternaria bataticola and Alternaria zinniae.     

Isolation and Identification of 2-Methylxanthopurpurin-7-methylether from the Mycelium of Alternaria porri

An attempt was made to estimate the base composition of DNA from UV absorption spectrum of its enzymatic digest. Preheated DNA sample was denatured, dialyzed and hydrolyzed to nucleotides with nuclease P1. A half of the digest was dialyzed and absorbance of the un-dialyzed digest was read at 16 different wavelengths with the dialyzed one as a reference. The data were input to a computer with standard extinction coefficients. The G+C contents thus obtained were fairly reproducible and reliable. An easier computing with a table calculator was found to be satisfactory for a routine work. It was noted that mathematically correct program does not always give reasonable answers. Base compositions of some DNA estimated by this method were also reported.     

Isolation of Alternaria Alternata from an Emollient Cream: Implications for Public Health

A specimen of emollient cream, which was observed to be contaminated peripherally with a filamentous fungus was examined for the presence of fungi and the resulting fungal colonies were examined phenotypically and genotypically. Subsequent DNA extraction and PCR amplification of the large internal transcribed spacer region [ITS1-5.8S-ITS2] yielded an amplicon of 512 bp. Sequence analysis identified this as Alternaria alternata at the 100% homology level with all 512/512 bases called. This organism has been previously reported as a cause of opportunistic infections involving skin and immunocompromised patients. This is the first report of an emollient cream as a source of this organism. It highlights the need for proper management of such preparations in order to minimize the potential spread of fungi to susceptible patient populations.     

Isolation and characterization of polymorphic microsatellite markers for Alternaria alternata

Alternaria alternata is of major significance as a food and feed contaminant and is able to produce a range of mycotoxins that may elicit adverse effects in both animals and humans. We describe the isolation and characterization of five microsatellite markers for studying A. alternata. Marker polymorphism was screened in 64 isolates of A. alternata. The number of alleles per locus ranged from eight to 24, and allelic diversity ranged from 0.425 to 0.882. These markers will be useful in the study of relationships and population genetics amongst isolates of A. alternata.     

Isolation of taxol producing endophytic fungus Alternaria brassicicola from non-Taxus medicinal plant Terminalia arjuna

World Journal of Microbiology and Biotechnology - Shigella type III effector OspF, a nuclear translocation protein, has been showed to have an essential role in Shigella flexneri infection and...     

Isolation and properties of beta-glucosidase from Ruminococcus albus

An enzyme active against p-nitrophenyl-beta-D-glucoside was purified from logarithmic-phase cells of Ruminococcus albus cultivated in a medium containing ball-milled cellulose. The purification yielded homogeneous enzyme after an approximately 520-fold increase in specific activity and a 9% yield. The enzyme was identified as a beta-glucosidase because it can hydrolyze cellobiose and cellooligosaccharides to glucose from the nonreducing ends.     

Isolation and properties of conjugated bilirubin from bile

1. A simple, rapid solvent partition method is described for isolation of conjugated bilirubin, free of unconjugated bilirubin, bile salts, phospholipids and cholesterol, from rat bile. Yields are 40-58%. The product is a phosphate-buffered solution containing approx. 0.4mg of bilirubin/ml, principally as mono- and di-glucuronide conjugates. The method may be modified for isolation of conjugates from human bile with 15-22% yield, and for preparation of unconjugated bilirubin from rat or human bile with yields of 55-62%. 2. The conjugated pigment has red-brown fluorescence and an absorption maximum at 450nm with in(mM) 59.8cm(-1). Diazotization by the Malloy-Evelyn method gives a direct Van den Bergh reaction (in water) 12% greater than the total reaction (in methanol), with in(total) 28.4x10(3)lmol(-1)cm(-1) at 550nm. After desalting by elution from Sephadex LH-20 in 50% (v/v) ethanol, the product gave water-soluble mustard-yellow crystalline needles. Such desalted conjugates were precipitated by Pb(2+) but not by Ba(2+), Ca(2+) or Zn(2+). 3. At pH7.0 and 37 degrees C the conjugated bilirubin was oxidized at a rate of 1%/h without hydrolysis, whereas 84% was hydrolysed by beta-glucuronidase or aqueous alkali. 4. Mono- and di-glucuronides were separated by elution from Sephadex LH-20 in 95% (v/v) ethanol or by extraction with chloroform at pH3.2-3.4. The monoconjugated bilirubin did not become labelled during incubation with unconjugated [(14)C]bilirubin, and chromatographed as a single spot without dissociating into unconjugated bilirubin and diglucuronide as would be expected of a complex. 5. After intravenous injection of mono- or di-conjugated [(14)C]bilirubin into normal or Gunn rats, 79-91% was excreted in bile and 2-7% in urine over 2h. In these experiments injected diglucuronide was not hydrolysed whereas 30-41% of injected monoglucuronide was converted into diglucuronide by the normal but not by the Gunn rats. The evidence favours the existence of a true bilirubin mono-glucuronide that is not a complex.