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Dive into the research topics where M. A. Choudhuri is active.

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Featured researches published by M. A. Choudhuri.


Aquatic Botany | 1982

Glycolate metabolism of three submersed aquatic angiosperms during ageing

Sasadhar Jana; M. A. Choudhuri

Abstract The glycolate metabolism of three submersed aquatic macrophytes, Potamogeton pectinatus L., Vallisneria spiralis L. and Hydrilla verticillata (L.f.) Royle, was studied by estimating the endogenous levels of glycolate and hydrogen peroxide (HP2O2) and assaying the activities of glycolate oxidase and catalase. The highest rate glycolate oxidase activity was recorded at pH 8.0, 7.6 and 7.4 for Potamogeton, Vallisneria and Hydrilla, respectively, while pH levels above and below this value markedly reduced the glycolate oxidase activity. The optimum glycolate oxidase activity of the three species was obtained when the reaction time was restricted to 10 min. Both the glycolate content and the activity of glycolate oxidase in the three leaf age groups (young, mature and old) were highest in mature leaves of these aquatic species. The glycolate content in mature leaves was highest in Hydrilla which also showed the lowest glycolate oxidase activity. Lowest glycolate content and highest glycolate oxidase activity were recorded in Potamogeton. An intermediate picture was observed in Vallisneria. The H2O2 content gradually increased with leaf age, while the catalase activity decreased. The content of H2O2 in mature leaves was highest in Vallisneria and lowest in Hydrilla. The catalase activity was also lowest in the former of the three species. During ageing of isolated mature leaves in the dark, there was a gradual decline in glycolate metabolism with increase in leaf age in Vallisneria and Hydrilla, but not in Potamogeton which showed a rise in glycolate oxidase activity after 3 days of induced ageing. Kinetin promotd glycolate metabolism in mature leaves of the three submersed plants during induced ageing, while ethrel and abscisic acid (ABA) showed an opposite effect.


Journal of Plant Growth Regulation | 2001

Role of auxin and polyamines in adventitious root formation in relation to changes in compounds involved in rooting

S. Nag; K. Saha; M. A. Choudhuri

An attempt was made to identify some cellular components that control adventitious root formation at the base of hypocotyl cuttings of mung bean (Vigna radiata L. cv. 105). Three phases of the adventitious root formation process were identified; induction (0-24 h), initiation (24-72 h), and expression (after 72 h). The lower peroxidase activity during the induction period (0-24 h) corresponded with the first peak of IAA at 24 h which indicated termination of the induction phase. A peak of peroxidase activity with low IAA levels at 72 h signaled the termination of the initiation phase. After 72 h, peroxidase activity declined and IAA levels increased slowly and this was characterized as the expression phase. IAA-oxidase activity could be inversely correlated with endogenous IAA levels. Endogenous putrescine and IAA increased simultaneously both at the induction and initiation phase, and might have a combined role in adventitious root formation. Spermidine and spermine levels did not change significantly throughout these phases. The pattern of diamine oxidase and polyamine oxidase (DAO/PAO) activities was inversely correlated with endogenous polyamine levels only during the induction phase. Levels of H 2 O 2 , which is involved in IAA and phenol oxidation and also in cell wall xylogenesis, were positively correlated with DAO/PAO activity because H 2 O 2 is one of the end products of PA oxidation. An inverse relationship between phenol content and polyphenol oxidase activity was observed during rooting of mung bean cuttings. Compared with controls, IBA-(10 -5 M) or PUT-(10 -4 M) treated cuttings exhibited increased levels of IAA, putrescine, phenol and H 2 O 2 , decreased IAA-oxidase activity, and increased DAO/PAO, peroxidase, and polyphenol oxidase activities. An early appearance of the second peak of putrescine and phenol at the end of the initiation phase (72 h) was observed in cuttings treated with IBA or PUT. On the basis of IAA levels and peroxidase activity, there was no change in the duration of different rooting phases due to IBA or PUT treatments. However, on the basis of endogenous PUT levels, treatment with IBA or PUT reduced the total duration of the initiation and expression phases.


Water Air and Soil Pollution | 1984

Synergistic effects of heavy metal pollutants on senescence in submerged aquatic plants

Sasadhar Jana; M. A. Choudhuri

The effects of many combinations of toxic concentrations of heavy metal pollutants, viz., mercuric chloride, lead acetate, cadmium chloride and cupric sulphate, on the senescence of isolated mature leaves of submerged aquatic plants, Potamogeton pectinatus L., Vallisneria spiralis L., and Hydrilla Verticillata (L.f) Royle were studied. All of the combinations of heavy metal pollutants caused senescence in all three species by decreasing chlorophyll, DNA, RNA, protein and dry wt, and increasing free amino acid, tissue permeability, the activities of protease and RNase, and the ratio of acid to alkaline pyrophosphatase activity over control values. The effects were highest in Potamogeton and lowest in Hydrilla. The degree of senescence in the three submerged plants by combinations of toxic concentrations of heavy metal pollutants is much higher due to synergism than that by individual heavy metal pollutants.


Plant Science | 2000

A rapid and sensitive assay method for measuring amine oxidase based on hydrogen peroxide-titanium complex formation.

Sudipa Nag; Kalpana Saha; M. A. Choudhuri

Hydrogenperoxide (H(2)O(2)) is an end product of diamine and polyamine oxidation by their respective oxidase enzymes. A new sensitive assay method is based on a H(2)O(2)-titanium (Ti) complex formation as an indicator of H(2)O(2) production due to polyamine oxidation. The orange-yellow coloured H(2)O(2)-Ti complex was measured at 410 nm in a Shimadzu spectrophotometer. The assay conditions for maximum diamine oxidase (DAO) and polyamine oxidase (PAO) as standardized here using the hypocotyl tissues of Vigna catjang Endl. cv Pusa Barsati consisted of pH 7.4 (40 mM potassium phosphate buffer), 3 mM substrate (putrescine or spermine), 37 degrees C incubation temperature and 30 min incubation time in the presence of catechol (10(-2) M) used as an inhibitor of both peroxidase and catalase activity. The method described here was significantly more sensitive than the starch-iodide method [T.A. Smith, Biochem. Biophys. Res. Commun. 41 (1970) 1452-1456], which could be improved further if measured under the same assay conditions as described for the H(2)O(2)-Ti method. Sensitivity of the present method was tested by assaying DAO/PAO activity in auxin treated hypocotyls of Vigna and comparing it with the starch-iodide method in two other plant samples.


Water Air and Soil Pollution | 1999

Monitoring of phytotoxicity of lead and mercury from germination and early seedling growth indices in two rice cultivars

Anita Mishra; M. A. Choudhuri

Treatment of seeds of two rice (Oryza sativa L.) cultivars (Ratna and IR36) separately with 10-5and 10-4M PbCl2and HgCl2decreased germination percentage, germination index (GI), shoot and root length, tolerance index (TI), vigour index (VI) and dry mass of shoot and root but increased percentage difference from control (% DFC) of germination and percentage phytotoxicity in both the cultivars. It was observed from these indices that the phytotoxic effect of mercury was greater than lead at identical concentrations and that IR36 appeared more tolerant than Ratna to these metals. Among the monitoring indices examined, TI, VI, and % phytotoxicity seemed to serve as good biological monitoring methods for evaluating the relative toxicity of lead and mercury to rice cultivars.


Aquatic Botany | 1981

Glycolate metabolism of three submersed aquatic angiosperms: Effect of heavy metals

Sasadhar Jana; M. A. Choudhuri

Abstract Glycolate metabolism and the effect of heavy metals e.g. mercury, lead, cadmium and copper, on glycolate metabolism of the three submersed aquatic macrophytes, i.e. Potamogeton pectinatus L., Vallisneria spiralis L. and Hydrilla verticillata (L.f.) Royle, were studied by estimating the endogenous levels of glycolate and hydrogen peroxide and assaying the activities of glycolate oxidase and catalase. The glycolate content was highest in Hydrilla , which also showed the lowest glycolate oxidase activity. Lowest glycolate content and highest glycolate oxidase activity was recorded in Potamogeton , while an intermediate state was observed in Vallisneria . The initial content of hydrogen peroxide was highest in Vallisneria and lowest in Hydrilla . The catalase activity was lowest in Vallisneria spiralis . Compared with the initial activity, the activity of the enzyme glycolate oxidase declined in Vallisneria and Hydrilla but rose in Potamogeton after three days of ageing of isolated leaves. Hydrogen peroxide content increased and catalase activity decreased in all three species during ageing. The highest content of hydrogen peroxide in Potamogeton was associated with maximum decline in catalase activity. The four heavy metals produced different effects on glycolate metabolism in the three species of aquatic macrophytes tested. All the heavy metals decreased glycolate content in Potamogeton , but in Vallisneria Hg and Cu caused it to increase while Pb and Cd gave a decrease. In Hydrilla , glycolate content decreased with Hg and Pb but increased with Cd and Cu. Glycolate oxidase activity was increased by Hg, Cd and Cu in Potamogeton , but decreased with Pb, whereas in Vallisneria this activity was decreased by Hg and Pb but increased by Cd and Cu. The activity of this enzyme was decreased by Hg, Cd and Cu but increased by Pb in Hydrilla . In Potamogeton and Vallisneria all the heavy metals except Pb increased H 2 O 2 content, while in Hydrilla the effect was reversed. Catalase activity was decreased by all the heavy metals in Potamogeton and Vallisneria but increased in Hydrilla . A metal stimulatory to glycolate metabolism when treated alone became inhibitory in the presence of another, and the inhibitory metals became stimulatory to this metabolism in combination treatments. It was concluded from these results that the glycolate metabolism was stimulated in Potamogeton and inhibited in Hydrilla by most of the heavy metals used. Vallisneria was intermediately affected by these metals.


Aquatic Botany | 1979

Photosynthetic, photorespiratory and respiratory behaviour of three submersed aquatic angiosperms.

Sasadhar Jana; M. A. Choudhuri

Abstract The rates of dark respiration, net and apparent photosynthesis and photorespiration in three submersed aquatic macrophytes, viz., Hydrilla verticillata (L.f.) Royle, Vallisneria spiralis L. and Potamogeton pectinatus L., were studied by estimating dissolved and gaseous O2. Among the three species, Hydrilla showed minimum dark and photorespiration and maximum apparent photosynthesis, while Potamogeton showed almost the reverse. The vigorous growth and dominance of Hydrilla and slender growth of Potamogeton in local ponds and lakes of this locality might be ascribed to these differences in physiological behaviour. Vallisneria was intermediate in this respect. Based on the above physiological characteristics, it was inferred that all the above three species are basically C3 plants. There was a gradual decline in physiological processes with increase in leag age in the case of Vallisneria. This age effect was also substantiated from data obtained from induced-ageing experiments. It was concluded that ageing has a similar effect on aquatic submersed macrophytes as in terrestrial plants.


Aquatic Botany | 1984

Effects of plant growth regulators on Hill activity of submerged aquatic plants during induced senescence

Sasadhar Jana; M. A. Choudhuri

Abstract Effects of plant growth regulators on Hill activity during induced senescence of leaves of three submerged aquatic plants Vallisneria spiralis L., Hydrilla verticillata (L.f.) Royle and Potamogeton pectinatus L., and a terrestrial plant Spinacia oleracea L. were studied. Hill activity was reduced by 39.3, 42.7, 45.2 and 245.1 μmol DCIP (2,6-dichloroindophenol) (mg chl) −1 h −1 in Vallisneria, Hydrilla, Potamogeton and Spinacia , respectively. During induced senescence of isolated mature leaves, Hill activity declined with increasing incubation time in all species. Kinetin (0.23 mM) treatment reduced the loss of Hill activity; while both 0.69 mM ehthrel and 0.075 mM ABA treatments decreased it in each species. The effect of kinetin was greatest in Spinacia , followed by Potamogeton, Hydrilla and Vallisneria , while the effect of either ethrel or ABA or both was greatest in Potamogeton , followed by Spinacia, Vallisneria and Hydrilla . Kinetin pre-treatment for an optimal period (12 h) followed by treatment with either ethrel or ABA partially removed the inhibitory effect of the latter on Hill activity. Pre-treatment of tissues with either ethrel or ABA solution, restricted to 12 h, followed by kinetin treatment markedly reduced the promotive effect of kinetin on the Hill activity of these species.


Aquatic Botany | 1982

Ethylene production and senescence in submerged aquatic angiosperms

Sasadhar Jana; M. A. Choudhuri

Abstract Ethylene evolution and its relationship with leaf senescence was studied in three submerged aquatic plants, Potamogeton pectinatus L., Vallisneria spiralis L. and Hydrilla verticillata (L.f.) Royle and in a terrestrial plant Spinacia oleracea L. The rate of evolution of ethylene gradually increased with age of intact leaves in all the four species. The highest rate was encountered in Potamogeton followed by Spinacia, Vallisneria and Hydrilla in all the age groups of leaves. During ageing of isolated mature leaves in the dark, there was a gradual increase in the rate, until it declined sharply at the senescent phase of the leaves of three aquatic species, except in Spinacia . Kinetin treatment suppressed ethylene production while ethrel and abscisic acid (ABA) enhanced it. The complex mechanisms of ethylene action in leaf senescence are discussed.


Journal of Plant Physiology | 1989

Effects of CaCl2 and ABA on Changes in H2O2, metabolism in two Jute Species under Water Deficit Stress

S. Roy Chowdhury; M. A. Choudhuri

Summary Pretreatment of seeds with calcium chloride (5.0 mM) or foliar spraying of ABA (0.01 mM) improved relative water content and leaf water potential of seedlings (45 days old) of two jute species, Corchorus capsularis (cv. JRC 212) and C. olitorius (cv. JRO 632), subjected to water deficit stress for 2 and 4 days in a potted condition. An additive improvement was noticed when seed treatment was followed by foliar spraying of ABA. With the improvement of water status in the treated plants, there was an increase in superoxide dismutase (EC 1.15.1.1) and catalase (EC 1.11.1.6) activity with a concomitant decrease in glycolate oxidase (EC 1.1.3.1) activity and hydrogen peroxide level under water deficit stress. A lesser formation of malondialdehyde in treated seedlings under water deficit stress suggested reduced lipid peroxidation and less membrane damage compared with untreated seedlings. The treatments possibly checked drought-induced injury through restoration of the water status of jute seedlings.

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R. K. Kar

University of Burdwan

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K. Saha

University of Burdwan

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S. Nag

University of Burdwan

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