Erratum Structural and functional organization of the `1S0.8 gene-rich region' in the Triticeae

Plant Molecular Biology 49: 791–804, 2002 Table 1 of this article was wrongly printed. The correct version is printed overleaf.     

Optimal production of cellulolytic enzymes and their location in trichoderma pseudokonigii

The maximum production of cellulose enzymes (FPactivity, CMcellulase and β-glucosidase) in the culture filtrate was observed at 27°C and pH 5.0, except for β-glucosidase, being at 6.0. The levels of extracellular enzymes in shake and stationary culture conditions was almost equal although they reached their maxima earlier in the former. The distribution of the three enzymes in extracellular, cytosol and cell debris fractions revealed most of the FPactivity and CMcellulase occurring extracellulary. More than 50% of the β-glucosidase was present in the cell debris fraction.     

Physical characterization of isozymes of endo-β-1,4-glucanase and β-1,4-glucosidase from Aspergillus species

Electrophoretic data revealed the presence of various isozymes of endoglucanase and beta-glucosidase, the number of which varied from one to three in various species of the genus Aspergillus. pH 5.0 was optimum for all the isozymes whereas metal ion treatment showed complete inhibition of almost all the isozymes by Hg2+ and partial inhibition by Ca2+ and Co2+ of isozymes of both the enzymes. An alteration in the electrophoretic mobility of isozymes of beta-glucosidase was also noticed in some species with Hg2+ treatment.     

Developmentally related changes in the production and expression of endo-beta-1,4-glucanases in Aspergillus nidulans

The production and electrophoretic expression of endoglucanase(s) were compared in the wild-type and three developmental mutants of Aspergillus nidulans. In the wild type, the production of endoglucanase and its distribution in extracellular and intracellular fractions varied with the age of the culture and the yield was better in stable cultures (production of conidia and cleistothecia) as compared with shake cultures (vegetative hyphae only). Two developmental mutants, aco-T69 and aco-40, which lack the development of conidia and cleistothecia, produced low levels of endoglucanase enzymes as compared with the wild type grown under similar conditions. On the other hand, in aco-90, a mutant capable of producing cleistothecia but no conidia, endoglucanase production was better. The results indicate a correlation between cleistothecial development and endoglucanase level. The electrophoretic studies revealed the presence of three forms of endoglucanase, i.e., EGI, EGII, and EGIII. The first two were detectable in the wild type as well as in mutant strains when grown under various experimental conditions and at all the stages of development. However, the third form could be observed only during cleistothecial development, indicating that this isozyme is developmentally regulated.     

Bacterial mutagenesis and hepatocyte unscheduled DNA synthesis induced by chrysoidine azo-dye components

5 azo dye components of Gurr chrysoidine 'Y' have been separated, synthesised and identified. Dyes with a methyl substitution (particularly between the two amino groups) were more mutagenic in Salmonella typhimurium strain TA100 with control rat liver S9 than the non-methylated counterpart (range 66-1992 revertants at 50 micrograms/plate). Mutagenicity was also catalysed by human-liver S9 and pre-treatment of rats with either phenobarbitone or beta-naphthoflavone enhanced the activation ability of S9 by greater than 4-fold. Using the most potent promutagenic component (2,4-diamino-3-methylazobenzene), the use of inhibitors of cytochrome P450 (metyrapone: 1.0 mM; alpha-naphthoflavone: 0.075 mM; DPEA: 0.125 mM) and of the flavin monooxygenase (methimazole: 0.75 mM) suggested a major role for cytochrome P448 in the activation of chrysoidine to mutagens. The ability of chrysoidine components to induce unscheduled DNA synthesis in rat hepatocytes in vitro was demonstrated and ranged between 11.92 and 23.5 net nuclear grains at a dose level of 2.5 micrograms/incubation. Since each dye was equi-potent, methyl substitution had little influence on genetic toxicity in hepatocytes.     

Studies on the air-borne fungal spores in Amritsar: Their role in keratomycosis

An aerial survey for fungal spores in Amritsar has been carried out by petri plate exposure method for a period of one year. A total of 23 fungi appeared in the plates. Out of these Aspergillus was the commonest fungus representing 21.69% of the total colony count followed by Alternaria, Curvularia and Fusarium. There was seasonal variation in the prevalence of fungal spores. A comparison of the prevalence of fungi in diseased and healthy eyes and the atmosphere of Amritsar appeasrs to support the view that these fungi are transient residents in the eyes depending on their availability in the atmosphere.Part of the data presented at the XXXVIII All India Ophthalmological Conference held at Amritsar from January 5–8, 1979.     

Molecular cloning of Bacillus polymyxa (1→4)-β-d-xylanase gene in Escherichia coli

Escherichia coli has been transformed with recombinant plasmids carrying DNA from Bacillus polymyxa. A sensitive and simple immunoassay was used to screen for E. coli transformed with the chimeric plasmid carrying a (1→4)-β-d-xylanase (1,4-β-d-xylan xylanohydrolase, EC 3.2.1.8) gene. One such clone was isolated. The enzyme present in extracts of these E. coli cells was active in catalysing the hydrolysis of (1→4)-β-d-xylo-oligosaccharides of identified structure from the mucilage of Plantago ovata Forsk, as indicated by the production of reducing sugars. This work holds promise for the large-scale production of xylanases as a new route to the economic and usable degradation of xylans and is a model for the large-scale production of enzymes.