scispace - formally typeset
Search or ask a question
Author

M. Sreekala

Bio: M. Sreekala is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Mimosine & Trigonella. The author has an hindex of 4, co-authored 4 publications receiving 49 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: The results including the differential response of GR activity to Se or mimosine supplementation are reflective of an effective reductive environment in Se groups and increased turnover of GSH in the presence of Mimosine.
Abstract: Actaptive alterations in glutathione (GSH) metabolism were studied during oxidative stress induced by selenium (Se) deficiency in germinating seedlings ofTrigonella foenum- graecum grown for 72 h and the response to supplementation individually of Se or mimosine was explored. Growth enhancement with improved mitochondrial efficiency was elicited by supplementation of Se at 0.5-0.75 ppm or mimosine at 0.1-0.2 mM. Total thiol and protein levels of mitochondrial and soluble fractions, in general, did not vary significantly with supplementation of either Se or mimosine except that the mitochondrial protein levels in mimosine groups (0.1-0.2 mM) decreased by 20–30%. Mitochondrial glutathione peroxidase (GSH-Px) increased by twofold in activity toward H2O2, cumene hydroperoxide (CHP), and t-butyl hydroperoxide (tBHP) in Se groups, and by 50–60% increase toward H2O2 and CHP but by a twofold enhancement in enzyme activity with tBHP in mimosine groups. Soluble GSH-Px activity increased by 30–40% only in mimosine groups and remained unaltered in Se groups. Glutathione S-transferase activity (GST) in the soluble fraction of both Se and mimosine groups increased dramatically by fivefold to sixfold. Distinct differences were noted in the response of the stressed seedlings toward exposure to Se or mimosine and included a decline in glutathione reductase (GR) activity by 50–60% in both mitochondria and soluble fractions of Se groups and an increase in GR activity of the mitochondria by twofold and of the soluble enzyme activity by 30% in the mimosine groups. Mimosine exposure resulted in a dose-dependent decrease in the γ-glutamyl transpeptidase levels, but, in contrast, a significant enhancement by 50% was noted in the Se group at 0.75 ppm. The results including the differential response of GR activity to Se or mimosine supplementation are reflective of an effective reductive environment in Se groups and increased turnover of GSH in the presence of mimosine.

23 citations

Journal ArticleDOI
TL;DR: It is demonstrated for the first time that mimosine, a naturally occuring toxic amino acid, could be a beneficial growth factor in concentrations between 0.1 and 0.2 mM.
Abstract: Oxidative stress during selenium (Se) deficiency in the seedlings ofTrigonella foenum-graecum grown for 72 h was investigated and the response to supplemented levels of Se (0.5-1 ppm) and mimosine (0.05-1 mM) was evaluated. Beneficial effects of Se was maximal at 0.75 ppm. Mimosine, a toxic amino acid, was also found to be beneficial to the growth of the seedlings exposed up to 0.2 mM. When compared to the stressed seedlings, mitochondrial oxygen uptake from seedlings of Se (0.75 ppm) group and mimosine (0.2 mM) group exhibited threefold enhancement in state 3 respiration rate and a controlled state 4 rate, with respiratory control ratios of 5–8. Upon supplementation at the optimal levels, Superoxide dismutase (SOD) activities were enhanced fourfold with Se and eightfold with mimosine in the mitochondria. The soluble activity in mimosine groups increased twofold, but only by 75% in Se groups. Peroxidase activity registered a significant increase by threefold in mitochondria and fourfold in soluble fraction in both Se and mimosine groups. Exposure to Se or mimosine exhibited a differential response in the mitochondrial catalase and ascorbate peroxidase (Asc-Px) activities. In the Se groups, both catalase and Asc-Px in mitochondria decreased by 50–60%, which was contrasted by 60% increase in Asc-Px activity and 40% in catalase activity in mimosine groups. Supplementation with either Se or mimosine evoked similar responses of increases with respect to soluble catalase by twofold to threefold and Asc-Px by 90%. The results of the present study reveal (1) the Prevalence of oxidative stress inT. foenum-graecum during Se deficiency, (2) enhanced mitochondrial functional efficiency mediated by Se and mimosine independently, and (3) an antitoxidative role for mimosine during Se deficiency. The study demonstrates for the first time that mimosine, a naturally occuring toxic amino acid, could be a beneficial growth factor in concentrations between 0.1 and 0.2 mM.

19 citations

Journal ArticleDOI
TL;DR: The study reveals a differential response to Se among the β-galactosidase and β-glucosid enzyme of T. foenumgraecum with increase in the levels of β-GalactOSidase activity.
Abstract: Beta-glucosidase and beta-galactosidase activity profile tested in different seeds during 24 h germination revealed reasonably high levels of activity in Vigna radiata, Cicer arietinum, and Trigonella foenum-graecum. In all seeds tested, beta-galactosidase activity was, in general, higher than that of beta-glucosidase. T. foenum-graecum seedlings exhibited maximal total and specific activities for both the enzymes during 72 h germination. Se supplementation as Na2SeO3 up to 0.75 ppm was found to be beneficial to growth and revealed selective enhancement of beta-galactosidase activity by 40% at 0.5 ppm Se. The activities of both the enzymes drastically decreased at 1.0 ppm level of Se supplementation. On the contrary, addition of Na2SeO3 in vitro up to 1 ppm to the enzyme extracts did not influence these activities. Hydrolytic rates of beta-glucosidase in both control and Se-supplemented groups were enhanced by 20% with 0.05 M glycerol in the medium and 30% at 0.1 M glycerol. The rates were marginally higher in Se-supplemented seedlings than the controls, irrespective of added glycerol in the medium. In contrast, hydrolysis by beta-galactosidase showed a trend of decrease in Se-supplemented seedlings compared to the control, when glycerol was present in the medium. Addition of Se in vitro in the assay medium showed no difference in the hydrolytic rate by beta-galactosidase when compared to control, while the activity of beta-glucosidase declined by 50%. Se-grown seedlings showed an enhancement of transglucosidation rate by 40% in the presence of 0.1 M glycerol. The study reveals a differential response to Se among the beta-galactosidase and beta-glucosidase of T. foenum-graecum with increase in the levels of beta-galactosidase activity.

6 citations

Journal ArticleDOI
TL;DR: The present study confirms the controlled nature of 75Se uptake by plant mitochondria, with a cooperative effect during Se transport and the interaction of active thiols in the process.
Abstract: Uptake of (75Se) added in vitro was followed in mitochondria isolated from Trigonella foenum-graecum seedlings grown under different Se status (0.5–1.0 ppm) and with added mimosine (0.1 mM). Uptake of 75Se followed with added Na275SeO3 upto 20 µM in the medium was nonlinear in all the groups. Kinetic analyses of the uptake of 75Se for 1 min were carried out for all the groups. The results indicated a cooperative effect during Se transport. Graphical analyses using the Hill plot and Scatchard plot confirmed the existence of negative cooperativity during 75Se uptake. Scatchard plots were biphasic, suggesting the probable presence of two classes of binding sites. The presence of succinate or ATP in the incubation medium inhibited 75Se uptake by 40%. Studies with mitochondrial respiratory inhibitors indicated the uptake to be energy independent. A decrease in the uptake of 75Se by 40% effected by HgCl2, N-ethyl maleimide, and iodoacetate confirmed the interaction of active thiols in the process. The present study confirms the controlled nature of 75Se uptake by plant mitochondria.

5 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: This review is to assess the mode of action and role of antioxidants in protecting plants from stress caused by the presence of heavy metals in the environment.
Abstract: The contamination of soils and water with metals has created a major environmental problem, leading to considerable losses in plant productivity and hazardous health effects. Exposure to toxic metals can intensify the production of reactive oxygen species (ROS), which are continuously produced in both unstressed and stressed plants cells. Some of the ROS species are highly toxic and must be detoxified by cellular stress responses, if the plant is to survive and grow. The aim of this review is to assess the mode of action and role of antioxidants in protecting plants from stress caused by the presence of heavy metals in the environment.

1,065 citations

Journal ArticleDOI
TL;DR: The results suggest that Se is an antioxidant or it activates protective mechanisms, which can alleviate oxidative stress in the chloroplasts, and improve the recovery of chlorophyll content following light stress.

209 citations

Journal ArticleDOI
TL;DR: Although there was no change in total biomass, Se treatment was associated with a 43% increase in seed production and the Se-treated Brassica plants had higher total respiratory activity in leaves and flowers, which may have contributed to higher seed production.
Abstract: Selenium (Se) is essential for humans and animals but is not considered to be essential for higher plants. Although researchers have found increases in vegetative growth due to fertiliser Se, there has been no definitive evidence to date of increased reproductive capacity, in terms of seed production and seed viability. The aim of this study was to evaluate seed production and growth responses to a low dose of Se (as sodium selenite, added to solution culture) compared to very low-Se controls in fast-cycling Brassica rapa L. Although there was no change in total biomass, Se treatment was associated with a 43% increase in seed production. The Se-treated Brassica plants had higher total respiratory activity in leaves and flowers, which may have contributed to higher seed production. This study provides additional evidence for a beneficial role for Se in higher plants.

181 citations

Journal ArticleDOI
TL;DR: In this article, the complementary role of selenium and sulfur specific chromatographic detection by HPLC with interfaced inductively coupled plasma mass spectrometry (ICP-MS) detection and by derivatization GC with interfacing atomic spectral emission was investigated.

124 citations

Journal ArticleDOI
TL;DR: This review attempts to appraise the literature related to non-protein amino acids, both in terms of their metabolism, plant–soil interactions and at the level of the ecosystem, where they are seen as significant drivers of structure and function.
Abstract: Non-protein amino acids are a significant store of organic nitrogen in many ecosystems, but there is a lack of knowledge relating to them. Research has indicated that they play important roles as metabolites, as allelopthic chemicals, in nutrient acquisition, in signalling and in stress response. They are also thought to be responsible for significant medical issues in both invertebrate and vertebrate animals. This review attempts to appraise the literature related to non-protein amino acids, both in terms of their metabolism, plant–soil interactions and at the level of the ecosystem, where they are seen as significant drivers of structure and function. Finally, important areas for future research are discussed.

120 citations