ABSTRACT
X-ray microanalysis of mesophyll and bundle sheath maize chloroplasts showed that bound manganese is located within thylakoids, whereas bound iron is equally present in thylakoids and stroma. A simple correlation between manganese content and oxygen evolution capacity (Photosystem II activity) is unlikely since Mn is also present in bundle sheath thylakoids of low Photosystem II activity. A major part of manganese has probably a distinct function and only a minor part plays a role in the process of oxygen evolution.
Subject(s)
Chloroplasts/analysis , Iron/analysis , Manganese/analysis , Chloroplasts/ultrastructure , Microscopy, Electron , Plants , Spectrum Analysis , Zea maysABSTRACT
X-ray microanalysis was performed on ultrathin sections of tissues from six rats, four of which having been exposed to experimental metabolic disorder by overdoses of NaCl and Ca-Vit. D2, respectively. It was demonstrated that the elements Cl, Si, P, S, Ca and traces of Fe are identifiable quantitatively in arteriolar walls of colon, heart and kidney even after conventional electron microscopic preparation (fixation, dehydration and Epon embedding). Depending on the pretreatment considerable differences in elemental quantities between animal groups were observed. The reliability of these findings must be confirmed by further tests on a greater number of individuals.
Subject(s)
Cations/analysis , Ergocalciferols/poisoning , Microchemistry/methods , Sodium Chloride/poisoning , Animals , Anions/analysis , Colon/metabolism , Colon/pathology , Kidney/metabolism , Methods , Myocardium/metabolism , Radiography , RatsABSTRACT
The effect of gibberellic acid (GA3) on ion ratios in a dwarf maize mutant (Zea mays L. d1) exhibiting normal growth after hormone treatment has been investigated by electron microprobe analysis. Gibberellic-acid treatment increased the ion content in chloroplasts and vacuoles whereas no change of the ion content was found in the cytoplasm. The relation of these observations to the action of the hormone is discussed.
ABSTRACT
Early effects of gibberellic acid (GA3) (1-4 h treatment) on the ion ratios in a dwarf maize mutant (Zea mays L. d 1) showing normal growth after hormone treatment, have been investigated by electron microprobe analysis. GA3 exerts a different effect on the ion ratios in plastids, cytoplasm and vacuoles in short term experiments. The Cl content of chloroplasts and cytoplasm increases without a lag phase after GA3 treatment. The K content of plastids increases after a lag phase of 2 h, whereas in the cytoplasm an increase can be observed immediately after GA3 addition. The hormone has only little influence on the Ca content of the cell compartments investigated. Control experiments with water and the physiologically inactive GA3 methylester confirm the specifity of the short-term actions of GA3 on the ion ratios. The primary action of GA3 at the membrane level is discussed.
