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Biomedical subjects

V V Modi

Publications and source records attributed to V V Modi.

At least 37 records · Page 2Linked to original sources
PubMed1981

Induction of extracellular proteases by egg-white in Aspergillus nidulans.

Aspergillus nidulans when supplemented with egg-white protein (1 %) produced considerable amounts of proteases extracellularly. The order of the appearance of the proteolytic enzymes growth on untreated and heat-inactivated egg-white were studied. They showed pH optima of 5, 7.2 and 9 when assayed at 37 degrees C. It is proposed that one of the factors leading to higher cell mass of A. nidulans in the presence of egg-white is the availability of protease-catalyzed hydrolyzed products of egg-white.

Aspergillus nidulans↗
PubMed1980

Involvement of cyclic AMP in carotenogenesis and cell differentiation in Blakeslea trispora.

Cyclic adenosine 3',5'-monophosphate (cyclic AMP) was detected in single and mated cultures of Blakeslea trispora. Cyclic AMP levels increased on mating the plus and minus mycelia. Trisporic acid and beta-carotene levels were much higher in synthetic mucor medium supplemented with glycerol as compared to that with glucose. Cyclic AMP induced significant morphological changes in plus and minus strains were comparable to those induced by mating event.

Carotenoids↗
PubMed1979

Comparative temperature-stability properties of malate dehydrogenases from some thermophilic fungi.

Temperature-activity and temperature-stability relationships of malate dehydrogenases from eight thermophilic fungi were determined. Temperature optima for maximum activity of the enzymes varied between 50 degrees and 60 degrees and the Arrhenius plots were linear between 5 degrees and 50 degrees. The energies of activation ranged from 2.1 Kcal/mol for the enzyme from Sporotrichum thermophile to 9.1 Kcal/mol for that from Penicillium duponti. Heat inactivation kinetics at 50 degrees revealed heat lability of the enzyme from most of the thermophilic fungi. The t1/2's (min) were less than 10 for the enzymes from P. duponti, S. thermophile and Thermoascus aurantiacus; less than 30 for those from Chaetomium thermophile var. coprophile, H. lanuginosa and C. thermophile var. dissitum; and greater than 30 for those from Mucor pusillus and H. insolens. Salts of Na+, K+ and NH4+, and citrate protected the enzymes from H. lanuginosa, C. thermophile var. dissitum and M. pusillus against heat inactivation.

Cations, Monovalent↗
PubMed1978

Stimulation of growth and glucose catabolite enzymes by succinate in some thermophilic fungi.

Thermophilic Humicola lanuginosa, Penicillium duponti, Sporotrichum thermophile and Mucor pusillus required succinate in addition to glucose for optimal growth. The requirement for succinate was concentration-dependent and the concentration needed for one half of the maximal growth was 6.14mM. In the presence of succinate, glucose utilization from the medium was markedly increased and this was associated with increased levels of the enzymes of the glycolytic and Krebs cycle pathways. Addition of succinate to cultures growing in glucose at any stage of growth stimulated the growth with the resulting rate of growth remaining high if the addition was made within 3 days of inoculation. Cycloheximide (71.4 micrometer) prevented the succinate-mediated derepression of the enzymes suggesting that succinate may remove the catabolite repression in the presence of glucose.

Cycloheximide↗
PubMed1978

Interaction between Rhizobium japonicum phage M-1 and its receptor.

The receptor for phage M-1 was present in the exopolysaccharide (EPS) of Rhizobium japonicum D211. The EPS was a heteropolysaccharide consisting of glucose, galactose, glucuronic acid, and glucosamine units. These monosaccharides prevented phage-cell attachment indicating that they may mimick the receptor. Phage-cell attachment was either stimulated or inhibited by Mg2+ and Ca2+ depending upon their concentration. An enzyme which depolymerized the exopolysaccharide releasing oligosaccharides was detected in the phage-infected cell lysates. A comparison of the properties of adsorption and those of the depolymerase enzyme indicated that the latter was a component of the phage and appeared to be involved in the phage-receptor interaction.

Adsorption↗
PubMed1977

Regulation of ammonia uptake in aspergillus nidulans.

The ammonia uptake in A. nidulans was found to be linear for about 20 min, and was proportional up to 1.5 mg/ml dry cell density. The transport of ammonia does not involve energy. Normal and biotin deficient A. nidulans showed an identical Km-values of 10.26 X 10(-5) M ammonia for uptake. The uptake of ammonium ion has been shown to be regulated by the intracellular concentration of ammonia.

Aspergillus nidulans↗
PubMed1977

Regulation of glucose transport in Aspergillus nidulans.

Pyruvate and acetate inhibited the uptake of glucose by Aspergillus nidulans; although there were significant variations in glucose uptake rate, the intracellular concentration of acetate was almost identical in biotin-supplemented, normal and deficient cells. The in vitro activity of glucose-binding protein was not affected by biotin, avidin, acetate or acetyl-CoA.

Acetates↗
PubMed1977

Growth, glucose metabolism and melanin formation in biotin-deficient Aspergillus nidulans.

Biotin deficiency resulted in an increased growth rate of Aspergillus nidulans. The activities of hexokinase and aldolase were not much changed during the growth cycle, but activities of glucose-6-phosphate dehydrogenase and NADP-linked glutamate dehydrogenase increased significantly during the exponential phase. This change was remarkable during biotin deficiency. In contrast to the higher growth rate and respiration rate during biotin deficiency the activities of NAD(P)H oxidoreductases were low. An inverse relationship between the activity of tyrosinase and melanin content was observed. A role of the DOPA-DOPA-quinone system in maintaining culture growth is suggested.

Aspergillus nidulans↗
PubMed1976

Assimilation of ammonia and growth of biotin deficient Aspergillus nidulans.

Biotin deficiency in Aspergillus nidulans has been found to increase the uptake of ammonium ions, associated with a marked increase in the activity of NADP-linked glutamate dehydrogenase, which is found to be the major route of ammonia assimilation in this culture. The results obtained are discussed with respect to the growth of Aspergillus nidulans during biotin deficiency.

Alanine↗