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Titolo:
REGULATION OF HEAVY-METAL TOXICITY IN ACID-TOLERANT CHLORELLA - PHYSIOLOGICAL AND BIOCHEMICAL APPROACHES
Autore:
RAI LC; RAI PK; MALLICK N;
Indirizzi:
BANARAS HINDU UNIV,DEPT BOT,ALGAL BIOL LAB VARANASI 221005 UTTAR PRADESH INDIA
Titolo Testata:
Environmental and experimental botany
fascicolo: 1, volume: 36, anno: 1996,
pagine: 99 - 109
SICI:
0098-8472(1996)36:1<99:ROHTIA>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
MEMBRANE H+-ATPASE; DUNALIELLA-ACIDOPHILA; CADMIUM TOXICITY; NOSTOC-MUSCORUM; PH; GROWTH; METABOLISM; NITROGEN; VULGARIS; NICKEL;
Keywords:
CHLORELLA VULGARIS; ACID-TOLERANT; SUPERACTIVE ATPASE; MEMBRANE POTENTIAL; PERMEABILITY; METAL TOXICITY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
34
Recensione:
Indirizzi per estratti:
Citazione:
L.C. Rai et al., "REGULATION OF HEAVY-METAL TOXICITY IN ACID-TOLERANT CHLORELLA - PHYSIOLOGICAL AND BIOCHEMICAL APPROACHES", Environmental and experimental botany, 36(1), 1996, pp. 99-109

Abstract

To explore the mechanism(s) of survival of the organism in acid- and metal-stressed environment and to test certain hypotheses, the growth rates, uptake of NH4+, Na+, K+, Ca2+, NO3-, PO43-, efflux of Na+ and K, activities of nitrate reductase, acid phosphatase and ATPase and internal pH of an acid-tolerant and an acid-sensitive strain of Chlorella vulgaris exposed to Cu and Ni at different pHs (pH 6.8, 5.0, 4.0 and3.5) were compared. A general reduction in all variables was noticed with decrease in pH; however, the acid-tolerant strain was metabolically more active than the acid-sensitive strain. Reduced cation (NH4+, Na+, K+, Ca2+, Cu2+ and Ni2+) uptake coupled with an increased concentration of anions (NO3- and PO43-) supported the hypothesis of the development of positive membrane/zeta potentials in the acid-tolerant strain. Further an accelerated accumulation of NO3- and PO43- in the cells and a significant increase in ATPase activity with decreasing pH at neutrality in the acid-tolerant strain either by exporting H+ ions into the external medium or by producing OH- ions from NO3-. The lower toxicity of Cu and Ni to the acid-tolerant strain compared to the acid-sensitive strain also supported our hypothesis of low metal uptake in theacid-tolerant strain due to cation repulsion by the membrane having low permeability and positive zeta and membrane potentials. The development of a superactive ATPase and a change in membrane potential and permeability not only offer protection against acidity by keeping internal pH neutral but also confer co-tolerance to metals.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/09/20 alle ore 02:36:14