ABSTRACT
Treatment of diphenyl ether herbicide acifluorfen-Na (AF-Na) to intact cucumber (Cucumis sativus L cv Poinsette) seedlings induced overaccumulation of protoporphyrin IX in light (75 mumole m-2 s-1). The extra-plastidic protoporphyrin IX accumulated during the light exposure disappeared within two hours of transfer of acifluorofen-treated seedlings to darkness. The dark disappearance was due to re-entry of migrated protoporphyrin IX into the plastid and its subsequent conversion to protochlorophyllide. In light, protoporphyrin IX acted as a photosensitizer and caused generation of active oxygen species. The latter caused damage to the cellular membranes by peroxidation of membrane lipids that resulted in production of malondialdehyde. Damage to the plastidic membranes resulted in damage to photosystem I and photosystem II reactions. Dark-incubation of herbicide-sprayed plants before their exposure to light enhanced photodynamic damage due to diffusion of the herbicide to the site of action. Compared to control, in treated samples the cation-induced increases in variable fluorescence/maximum fluorescence ratio and increase in photosystem II activity was lower due to reduced grana stacking in herbicide-treated and light-exposed plants.
Subject(s)
Cucumis sativus/drug effects , Herbicides/pharmacology , Nitrobenzoates/pharmacology , Oxidative Stress , Protoporphyrins/pharmacologyABSTRACT
1) A beta agonist stimulated Na+ transport and decreased the intracellular Cl concentration ([Cl]c) associated with cell shrinkage via an increase in cytosolic cAMP level by activating adenylate cyclase in rat fetal distal lung epithelial (FDLE) cells. 2) Lowering [Cl-]c activated a 28-pS nonselective cation (NSC) channel by elongating the open time of the channel. 3) cAMP signals were converted to a protein tyrosine kinase (PTK)-mediated signal. 4) The PTK-mediated signal was involved in the cAMP-stimulated Na+ transport in rat FDLE cells.
Subject(s)
Female , Pregnancy , Rats , Adrenergic beta-Agonists/pharmacology , Animals , Biological Transport/physiology , Biological Transport/drug effects , Cell Size/physiology , Chlorides/metabolism , Cyclic AMP/metabolism , Cytosol/metabolism , Enzyme Inhibitors/pharmacology , Fetus/cytology , Colforsin/pharmacology , Nitrobenzoates/pharmacology , Protein-Tyrosine Kinases/metabolism , Rats, Wistar , Respiratory Mucosa/enzymology , Respiratory Mucosa/embryology , Respiratory Mucosa/cytology , Sodium/metabolism , Tyrphostins/pharmacologyABSTRACT
The indirect susceptibility test results on L-J medium for tubercle bacilli against streptomycin, isoniazid and rifampicin were read at the end of 2 wk and compared with the results at 4 wk. It was found that drug resistance could be correctly predicted in over 70 per cent of cultures including multi-drug resistant tuberculosis (MDR TB) strains at the end of 2 wk. The susceptibility to para-nitrobenzoic acid (PNB) read at 2 wk was able to distinguish non-tuberculous mycobacteria from Mycobacterium tuberculosis cultures. The early detection of resistance by this procedure requires only minimum inputs, and can benefit the majority of patients harbouring drug resistant tubercle bacilli.