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Biomedical subjects

M Prasad

Publications and source records attributed to M Prasad.

At least 91 records · Page 5Linked to original sources
PubMed1980

Changes in the composition of free amino acids and sugars of leaf sheath and culm of wheat during uredospore and teleutospore formation of Puccinia graminis tritici.

There were altogether fourteen amino acids in leaf sheath and culm of wheat infected with Puccinia graminis tritici, especially in and around uredial and telial pustules. Valine, tyrosine, and proline, due to their exclusive presence in uredial pustules on leaf sheath and culm of wheat, were involved in the eruption of uredospores of P. graminis tritici. Glutamic acid and dl-threonine were, however, involved in a different manner during uredospore differentiation; their amounts diminishesd parallel to sporulation. The other amino compounds, detected in and around uredial and telial pustules on leaf sheaths and culms, were l-leucine/isoleucine, beta-phenylalanine, beta-alanine, glycine, serine, aspartic acid, homoserine, and glutamine. The amounts of these amino acids either remained the same or were lowered during uredo- and teluto-spores formation, except for serine which increased in its amount. The depletion of these amino compounds indicated their metabolic activity and utilization for uredo- and teleuto-spores differentiation of P. graminis tritici. Sucrose, glucose, and fructose, among sugars, were also utilized as their amounts diminished, for uredo- and teleuto-spores formation.

Amino Acids↗
PubMed1980

Variations in amino acids and sugars in different tissues of broad bean (Vicia faba L.) during the pathogenesis of Uromyces fabae (Pers.) de Bary.

In response to infection by the rust pathogen Uromyces fabae the different tissues of broad bean (Vicia faba L.) showed varied pattern of amino acid metabolism; some of them being exclusively present in a particular region only. In the inflorescence tissue, for example, tryptophan, glycine, aspartic acid, serine, proline, and arginine were present. In the stem, however, the amino acids, present during and after infection, were tryptophan, serine, glutamine, homoserine, and dl-alanine. Post-infectionally induced amino compounds, lysine, histidine, vomoserine, proline, tyrosine and dl-threonine, were found in the leaves; in the petiole serine and histidine were the only two such amino acids. Out of these amino acids only histidine and proline, with their specific presence and activity, encouraged uredospore differentiation. L-cysteine, too, by being actively utilized, served as promoter of uredosporulation. Asparagine and methionine showed moderate to heavy depletion during bean tissue infection. On the other hand, l-leucine/isoleucine, beta-alanine, valine, and glutamic acid showed moderate to pronounced increase during pathogenic establishment. Concomitant to uredospore differentiation there was a drastic lowering in the amount of sucrose in leaf and petiole tissue. The amount of glucose also declined during pathogenesis.

Amino Acids↗
PubMed1980

Effect of vitamins on growth and sporulation of Alternaria alternata (Fr.) Keissler.

Alternaria alternata, a leaf spot pathogen of beet (Beta vulgaris), was found to be auxoautotrophic for thiamine. On the other hand, riboflavin, biotin, inositol, and pyridoxine were heterotrophically needed for its growth. Vigorous sporulation was prominent in response to the additions of riboflavin, d-biotin, and inositol. A curiously depressent effect on both the growth and sporulation of the pathogen was noticed in presence of 1-ascorbic acid, folic acid, and nicotinic acid. These substances also lowered the pH of the medium towards acidity. Separate additions of thiamine, riboflavin, pyridoxine, biotin, and inositol, however, increased the pH towards the neutral and alkaline range.

Alternaria↗
PubMed1980

Interaction between age of maize plants, environmental factors, and inoculum strength of Erwinia carotovora var. chrysanthemi on the extent of stalk rot incidence.

For optimum disease incidence and maximum mortality of maize plants, due to Erwinia carotovora var. chrysanthemi (Burkholder et al.) Dye, a temperature of 35 degrees C accompanied with 70 per cent humidity and inoculum potency of 2 x 10(8) cells/ml were essential for younger plants of 15 and 30 days of age. On the other hand, 45- and 60-day-old plants, due to acquisition of a certain degree of maturity, although responding and showing maximum disease symptoms at the same temperature of 35 degrees C, required a higher humidity of 90 per cent. A heavy dose of 4 x 10(8) cells/ml was needed for effectual disease response for 45- and 60-day-old and mature plants.

Erwinia↗
PubMed1979

Comparative studies with regard to the influence of carbon and nitrogen ratio on sporulation in Fusarium oxysporum and Fusarium moniliforme v. subglutinans.

Carbon/nitrogen ratio as a factor for sporulation, expressed in terms of magnitude of population variation of macroconidia and microconidia in the cultures of Eusarium oxysporum Schlecht ex. Fr., Fusarium moniliforme v. subglutinans Wr. and Rg., and of chlamydospores (only in Fusarium oxysporum) was investigated. It has been found that the amount of carbon source shapes the course of macro- and micro. conidial production in a linear fashion, being enhanced parallel to the increase in its amount-Nitrogen level, limiting proliferation and effectively diminishing the macro- and micro-conidial population, varies for the two species, namely Fusarium oxysporum and Fusarium moniliforme v-subglutinans. For chlamydomspore production, higher carbon and still higher nitrogen concentration favours profuse proliferation in case of Fusarium oxysporum.

Carbon↗
PubMed1979

The free amino acid pool composition during growth of the culture of Xanthomonas citri (Hasse) Dowson.

Fourteen amino acids were found to constitute the intracellular amino compound pool of the developing culture of Xanthomonas citri (Hasse) Dowson. These were serine, dl-alanine, beta-alanine, leucine/isoleucine, threonine, aspartic acid, glutamic acid, asparagine, glutamine, cystine, histidine, tyrosine, tryptophan, and proline. Of these, beta-alanine, threonine, aspartic acid, glutamic acid, asparagine, and tyrosine could be traced as excretory amino acids in the bacterial culture filtrate, being exuded at the cost of and parallel to the depletion of their amounts in bacterial cell extract. Thus, the composition and pool size of intra- and extracellular amino acids varies considerably during the growth of this pathogen. The wall constituents of X. citri, especially alanine, glutamic acid, and aspartic acid, were prominent among the amino compounds detected.

Alanine↗
PubMed1979

Amino acid content in relation to growth of Helminthosporium maydis Nishikado and Miyake.

During the growth period of thirty days, altogether thirteen amino acids showed their presence and activity in the developing culture of Helminthosporium maydis Nishikado and Miyake. Initiation of growth by the 5th day coincided with the appearance of profuse amounts of dl-alanine and serine, and moderate amounts of valine, threonine, and aspartic acid. The thirteen amino acids, which appeared in full complement by the 15th day, were actively engaged in accelerating mycelial accumulation. Beyond this growth period, there was a decline in the amino acids.

Amino Acids↗
PubMed1979

Varying spectrum of amino acids in relation to growth in Helminthosporium oryzae Breda de Haan.

Fifteen amino acids were detected in the developing mycelium of Helminthosporium oryzae Breda de Haan. During the first fortnight of mat accumulation, which was more rapid, a marked influence of amino acids on the growth pattern was discernible. A high level maintenance of dl-alanine l-cysteine, l-leucine/isoleucine, threonine, tyrosine, glutamic, and aspartic acids, as well as an increase in the amount of gamma-aminobutyric acid and proline during the first fortnight of culture development were effective in initiating growth and keeping it at a more rapid pace. Glutamine and methionine appeared in the latter half of fungal growth. During this slow pace of mycelial accumulation in the latter half period, there was a general and overall decline in the amount of most of the amino acids. The amino acids started disappearing from the mycelial extract from the 20th day onwards till the end of the 30th day. In the culture filtrate, aspartic acid and proline appeared during the rapid growth phase and dl-alanine and methionine during the slower phase.

Amino Acids↗
PubMed1979

Fluctuation in amino-acid constituents of a developing culture of Sclerotium rolfsii Sacc. and its relation to growth.

Altogether eleven amino acids were detected in the mycelial extract of Sclerotium rolfsii Sacc. Here, with the appearance of aspartic acid and homoserine on the 5th day, growth was initiated. The maximum mycelial output, achieved by the 15th day, coincided with the detection of leucine/isoleucine and valine in the mycelial extract and of methionine in the culture filtrate. Lysine and gamma-amino-butyric acid which appeared late in the mycelium did not contribute to its growth. Tyrosine, an aromatic amino acid, was present only in the culture filtrate and not in the fungal extract. Aspartic acid, homoserine, and methionine were profusely produced in the culture filtrate during the decline of mycelial growth, suggesting that these amino acids could be fungal autolysis products as well.

Amino Acids↗