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1.
Indian J Exp Biol ; 2007 Apr; 45(4): 385-9
Artigo em Inglês | IMSEAR | ID: sea-57534

RESUMO

Supply of cadmium chloride (0.5 mM) inhibited chlorophyll formation in greening maize leaf segments, while lower concentration of Cd (0.01 mM) slightly enhanced it. Inclusion of 2-oxoglutarate (2-OG, 0.1-10 mM) in the incubation mixture increased chlorophyll content in the absence as well as presence of Cd. Substantial inhibition of chlorophyll formation by Cd was observed at longer treatment both in the absence and presence of 2-OG. When the tissue was pre-incubated with 2-OG or Cd, the inhibition (%) of chlorophyll formation by Cd was lowered in the presence of 2-OG. Treatment with Cd inhibited ALAD activity and ALA formation and the inhibition (%) of ALA formation by Cd was strongly reduced in the presence of 2-OG. Glutamate dehydrogenase (GDH) activity was increased by the supply of Cd both in the absence as well as presence of 2-OG. In the presence of 2-OG, Cd supply significantly increased glutamate synthase (GOGAT) activity and reduced inhibition (%) of glutamine synthetase (GS) activity. The results suggested the involvement of the glutamine synthetase/glutamate synthase (GS/GOGAT) pathway of ammonia assimilation to provide the precursor, glutamate, for ALA synthesis under Cd toxicity and 2-OG supplementation.


Assuntos
Ácido Aminolevulínico/antagonistas & inibidores , Cloreto de Cádmio/farmacologia , Clorofila/antagonistas & inibidores , Ácidos Cetoglutáricos/farmacologia , Folhas de Planta/efeitos dos fármacos , Sintase do Porfobilinogênio/antagonistas & inibidores , Compostos de Amônio Quaternário/metabolismo , Zea mays/efeitos dos fármacos
2.
Indian J Biochem Biophys ; 1990 Feb; 27(1): 5-8
Artigo em Inglês | IMSEAR | ID: sea-26994

RESUMO

Inhibition of photosystem II (PS II) activity by 8-hydroxyquinoline (8-HQ) has been investigated in case of spinach chloroplasts and isolated photosystem II particles using the thermoluminescence technique. In presence of 8-HQ, water to methylviologen (MV) photoreduction in isolated chloroplasts is inhibited while the reduction of dichlorophenol indophenol is inhibited in both chloroplasts as well as in photosystem II particles. The activity can be restored fully by addition of diphenylcarbazide (DPC), suggesting that the donor side of water oxidation complex is affected. The changes in the thermoluminescence peaks indicate that the charge recombination processes involving S2 or S3 states of the Kok's cycle are probably affected by 8-HQ treatment.


Assuntos
Quelantes/farmacologia , Clorofila/antagonistas & inibidores , Cloroplastos/efeitos dos fármacos , Hidroxiquinolinas/farmacologia , Complexos de Proteínas Captadores de Luz , Oxirredução , Oxiquinolina/farmacologia , Complexo de Proteínas do Centro de Reação Fotossintética , Complexo de Proteína do Fotossistema II , Proteínas de Plantas/antagonistas & inibidores , Dosimetria Termoluminescente , Água/metabolismo
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