Separation and quantification of monothiols and phytochelatins from a wide variety of cell cultures and tissues of trees and other plants using high performance liquid chromatography.

The HPLC method presented here for the quantification of metal-binding thiols is considerably shorter than most previously published methods. It is a sensitive and highly reproducible method that separates monobromobimane tagged monothiols (cysteine, glutathione, gamma-glutamylcysteine) along with polythiols (PC(2), PC(3), PC(4) and PC(5)) within 23min from a wide variety of samples. Total run time of the method is 35min. Detection limits for thiols is 33fmol for 10microlL injection. This method will be applicable to study the metal detoxification mechanisms for a wide variety of cell cultures and tissues of plants and trees including algae, Arabidopsis, crambe, rice, and red spruce.

Endocrine response of the freshwater teleost, Sarotherodon mossambicus (Peters) to dimecron exposure.

The endocrine response in a freshwater teleost, Sarotherodon mossambicus (Peters) under dimecron (an organophosphate pesticide) toxicity was investigated by estimating the serum levels of T3 (triiodothyronine), T4 (thyroxine), cortisol, prolactin and insulin in control and sub-lethal (0.001 ml l(-1)) dimecron-exposed fish for 1, 6, 12, 24h and 5 days. In control S. mossambicus, the serum levels of T3 ranged from 0.80+/-0.01 to 0.82+/-0.01 ng ml(-1); T4 from 2.20+/-0.01 to 2.25+/-0.01 microg dl(-1); cortisol from 8.30+/-0.03 to 8.34+/-0.01 microg dl(-1); prolactin from 1.50+/-0.01 to 1.54+/-0.01 microg ml(-1); insulin from 9.70+/-0.01 to 9.76+/-0.01 microU ml(-1) up to a maximum period of 5 days maintained in pollutant-free tap water. Exposure of fish to sub-lethal concentration of dimecron caused varying changes in the levels of serum hormones studied. Based on the results obtained, it was concluded that (i) the fish adaptively maintains a probable low metabolic rate, as indicated by the reduced levels of thyroid hormone (T3) as well as the glucocorticoid hormone (cortisol), which could be considered advantageous for the fish to indirectly reduce the toxic impact of the pesticide, (ii) the elevated levels of prolactin in the fish under pesticide stress is indicative of a possible hydromineral regulatory effect of the hormone (probably by influencing specific organs such as gills and kidney) under pesticide toxicity, (iii) the increased insulin level in the fish under pesticide stress is indicative of its role in favouring an adaptive tissue glycogenesis besides a possible increased lipogenesis to sequester the pesticide residue thereby reducing the toxic effect of the pesticide and (iv) the prolonged exposure of the fish (for 5 days) to sub-lethal dimecron appeared to exhibit a uniform recovery response in the different hormonal levels of the fish.

Influence of aluminium on the restoration potential of a terrestrial vascular plant, Portulaca Oleracea L. as a biomonitoring tool of fresh water aquatic environments.

In the present study, the influence of aluminium on the regeneration potential of leaf and stem-cuttings of Portulaca oleracea was studied in order to identify a terrestrial plant species as an alternate biomonitoring tool of fresh water environment. The leaves and stem cuttings of the terrestrial plant, P. oleracea grew well in the distilled water producing adventitious and lateral roots. The aluminium treated leaves and stem cuttings showed a reduction in the growth of the adventitious and lateral roots and increase in the decay of leaves and stem cuttings with increasing aluminium concentration. The tolerance index calculated for the leaves and the stem cuttings showed that the leaves were more sensitive than stems to aluminium. Since all the parameters studied showed concentration dependent changes, the terrestrial plant, P oleracea can be considered a suitable 'biomonitoring tool' of fresh water environment besides its usage in the Al toxicity testing.

Interactive effects of selenium and mercury on the restoration potential of leaves of the medicinal plant, Portulaca oleracea Linn.

Leaves of Portulaca oleracea have the potential of regeneration, when grown in a distilled water medium. The two heavy metals, Se and Hg individually and in combination affected both shoot and root development. They completely arrested shoot development at all concentrations. However, they produced concentration-dependent changes in the development of roots, which ranged from their complete inhibition to variation in their initiation time, number and length. Leaf decay was initiated on day 46 in control leaves. Concentration-dependent changes were also observed in the time of initiation and magnitude of decay of leaves. The data indicates that Hg was more toxic than Se. The protective effect of Se against Hg toxicity was evident only at very low concentrations. With further increases in the concentration of both Se and Hg, the protective effect decreased and simultaneously the toxicity increased. Following the decay of leaves, a pink colour development was observed only on leaves exposed to Se. Microbial analysis of leaves showed the presence of Acinetobacter only in Se-exposed leaves. Acinetobacter was therefore considered as probably involved in the formation of elemental Se, which produced a pink colour.

Effect of trace metals on the restoration potential of leaves of the medicinal plant, Portulaca oleracea Linn.

The effect of Cd, Cu, Zn, Hg, and Pb solutions at various concentrations, on the restoration potential of the leaves of Portulaca oleracea was tested. All the trace metals completely affected the shoot regeneration. The degree of their effect on root regeneration, however, varied. Early initiation of parental leaf decay was also observed. The order of their relative effect on the regeneration process was: Cd > Cu > Zn > Hg > Pb.