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1

Nowe zadania białkowych przyzwoitek

100%
Srivastava P. K.
Świat Nauki
|
2009
|
nr 01
2

Impact of low and high fluence rates of UV-B radiation on growth and oxidative stress in Phormidium foveolarum and Nostoc muscorum under copper toxicity: differential display of antioxidants system

51%
Singh V. P., Srivastava P. K., Prasad S. M.
Acta Physiologiae Plantarum
|
2012
|
tom 34
|
nr 6
In the present study, impact of low (UV-BL) and high (UV-BH) fluence rates of UV-B on growth, oxidative stress and antioxidant system was studied in two cyanobacteria i.e. Phormidium foveolarum and Nostoc muscorum under Cu (2 and 5 µM) toxicity after 24 and 72 h of experiments. UV-BH and Cu treatment decreased growth of both the cyanobacteria and Cu induced decrease in growth was accompanied by a significant increase in Cu accumulation. Levels of reactive oxygen species (ROS), i.e. superoxide radicals (SOR; O₂⁻ ) and hydrogen peroxide (H₂O₂) were significantly increased by Cu and UV-BH exposure which in turn accelerated lipid peroxidation (malondialdehyde: MDA) and protein oxidation (reactive carbonyl groups: RCG). Activities of enzymatic antioxidants, such as superoxide dismutase (SOD), peroxidase (POD) and glutathione-S-transferase (GST) were increased by both doses of Cu as well as UV-B. Conversely, Cu and UV-BH drastically decreased catalase (CAT) activity. After the commencement of 24 h of treatment with Cu alone and together with UV-BH, non-protein thiols (NP-SH) contents were decreased while after 72 h, a reverse trend was noticed. Unlike NP-SH, cysteine content decreased appreciably during the treatments. In contrast to this, low dose (UV-BL) of UV-B did not influence growth, SOR, H₂O₂, MDA and RCG contents. An improvement in CAT activity and NP-SH content was observed under Cu and UV-BL treatment; hence, UV-BL treatment resulted into certain degree of protection against Cu toxicity in both the organisms. Thus, the results showed that UV-BH and UVBL exerted differential effects on both the organisms under Cu toxicity, and compared to N. muscorum, P. foveolarum was less affected by Cu and UV-BH.
3

Modification of chromium (VI) phytotoxicity by exogenous gibberellic acid application in Pisum sativum (L.) seedlings

51%
Gangwar S., Singh V. P., Srivastava P. K., Maurya J. N.
Acta Physiologiae Plantarum
|
2011
|
tom 33
|
nr 4
Effects of exogenous gibberellic acid (GA; 10 and 100 µM) application on growth, protein and nitrogen contents, ammonium (NH₄⁺) content, enzymes of nitrogen assimilation and antioxidant system in pea seedlings were investigated under chromium (VI) phytotoxicity (Cr VI; 50, 100 and 250 µM). Exposure of pea seedlings to Cr and 100 µM GA resulted in decreased seed germination, fresh and dry weight and length of root and shoot, and protein and nitrogen contents compared to control. Compared to control, Cr and 100 µM GA led to the significant alteration in nitrogen assimilation in pea. These treatments decreased root and shoot nitrate reductase (NR), glutamine synthetase (GS) and glutamine 2-oxoglutarate aminotransferase (GOGAT) activities (except 50 µM Cr alone for GOGAT) while glutamate dehydrogenase (GDH) activity and NH₄⁺ content increased. Compared to control, the root and shoot activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) increased (except APX activity at 250 µM Cr + 100 µM GA) while catalase (CAT), glutathione reductase (GR) and dehydroascorbate reductase (DHAR) activities were decreased (except GR at 100 µM GA alone) following exposure of Cr and 100 µM GA. Total ascorbate and total glutathione in root and shoot decreased by the treatments of Cr and 100 µM GA while their levels were increased by the application of 10 µMGA compared to Cr treatments alone. It has been reported that application of 10 µM GA together with Cr alleviated inhibited levels of growth, nitrogen assimilation and antioxidant system compared to Cr treatments alone. This study showed that application of 10 µM GA counteracts some of the adverse effects of Cr phytotoxicity with the increased levels of antioxidants and sustained activities of enzymes of nitrogen assimilation; however, 100 µM GA showed apparently reverse effect under Cr phytotoxicity.
4

Light intensity determines the extent of mercury toxicity in the cyanobacterium Nostoc muscorum

45%
Singh R., Srivastava P. K., Singh V. P., Dubey G., Prasad S. M.
Acta Physiologiae Plantarum
|
2012
|
tom 34
|
nr 3
The extent of mercury (Hg) toxicity in the heterocystous cyanobacterium Nostoc muscorum grown for 72 h in three different light intensities was tested for various physiological parameters viz. growth, pigment contents, photosynthesis, respiration, reactive oxygen species (ROS), malondialdehyde formation and antioxidants. A general reduction in growth and pigments, whole cell O₂- evolution, photosynthetic electron transport activities and ¹⁴CO₂-fixation was observed in a metal concentration–dependent manner, and this effect was more pronounced in high light (130 µmol photon m⁻² s⁻¹)–exposed cells as compared to low (10 µmol photon m⁻² s⁻¹) and normal (70 µmol photon m⁻² s⁻¹) light intensity–exposed cells; however, carotenoids and respiration showed reverse trend. Among photosynthetic electron transport activities, whole chain activity was found to be most sensitive in comparison with photosystem II (PS II) and photosystem I (PS I). Comparing the different photosynthetic processes, ¹⁴CO₂-fixation was most affected in cyanobacterial cells when exposed to Hg and different light intensities. After application of various exogenous electron donors, diphenyl carbazide was found to be more effective to restore PS II activity, suggesting that site of damage lies in between oxygen evolving complex and PS II. Level of oxidative stress (superoxide radical and lipid peroxidation) was maximum at 3.0 µM of Hg when coupled with high light intensity (except hydrogen peroxide). A dose-dependent increase in enzymatic antioxidants such as superoxide dismutase, peroxidase and catalase as well as non-enzymatic antioxidants such as proline, ascorbate, cysteine (except under high light intensity) and non-protein thiols [NP-SH] was observed, which further increased with the increase in light intensity. It was noticed that Hg intoxicates N. muscorum through ROS production, which is aggravated along with the increase in light intensity. Overall results suggest that the severity of the metal stress does increase with Hg concentrations but when coupled with light, it was the light intensity that determines the extent of Hg toxicity.
5

Influence of ecological factors on the patterns of fish species richness in tropical Indian rivers

39%
Das M. K., Naskar M., Mondal M. L., Srivastava P. K., Dey S., Rej A.
Acta Ichthyologica et Piscatoria
|
2012
|
tom 42
|
nr 1
Background. Rivers in India harbouring a rich diversity of fish are at present subjected to intense anthropogenic stress leading to degradation of the habitat. An understanding of the complex ecological variables determining species richness in these rivers is lacking. The relation between the ecological parameters (climate, hydrology, and morphometry) and the fish species richness were assessed in fourteen major rivers of India. Materials and Methods. The data of seven ecological variables of fourteen major rivers of India for the years 1994–2009 were quantitatively analysed for determining their influence on fish species richness. Principal factor analysis (PFA) was carried out for dimension reduction and eliminating collinearity. Subsequently, fish richness was regressed on the retained factors under generalised linear model (GLM) for determining contribution of factors towards species richness in rivers. Results. The most influential determinants of species richness were the factors such as: surface area of the river basin (0.439) followed by fish habitat availability potential (0.326) a synthesis of the variables rainfall, discharge and sediment load. The predicted loss of fish species is evident at a 10% alteration in the ecological variables of the rivers. Conclusion. The predicted loss of fish species richness is indicated at a10% alteration of the habitat factors in most of the rivers and can be useful for river planners and conservationists.
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