Date of Award:

5-1-1977

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Life Sciences:Biology

Committee Chair(s)

Gene W. Miller

Committee

Gene W. Miller

Committee

Nabil N. Youssef

Committee

Joseph Street

Committee

Raymond Lynn

Committee

Herman Wiebe

Abstract

Oxidative respiration and morphological changes in soybean mitochondria isolated from etiolated hypocotyls were investigated, Aliquots from mitochondria in defined respiratory states were negatively stained with isotonic aqueous ammonium molybdate, pH 7.2. Similar experiments were conducted with mitochondria incubated for three minutes in an assay medium containing either 1.5, 3.0 or 6.0 x 10-2 M KCl or KF prior to the addition of either L-malate or succinate. Neither KCl nor KF affected the biochemical integrity of mitochondria judged on their ability to reduce both ADP/0 and respiratory control ratios, even though KF had a definite inhibitory effect on the rate of substrate oxidation. Fluoride progressively reduced respiratory control ratios in mitochondria oxidizing succinate but had no effect on ADP/0 ratios. Respiratory control in mitochondria oxidizing malate was not reduced but 6.0 x 10-2 M KF lowered the ADP/0 ratio. Respiratory control was increased in some experiments due to inhibited state IVb oxidation by either KCl or KF. Different morphological membrane configurations were observed in mitochondria freshly isolated, in various respiratory states and treated with either KCl or KF. Membrane configurations were not associated with respiratory state. Expanded and contracted mitochondria, as well as intermediate forms, were present in all preparations. The outer mitochondrial membrane was measurably damaged when treated with either KCl or KF for three minutes prior to oxidative measurement. Fluoride treated mitochondria exhibited statistically greater damage than KCl treated mitochondria. No visible effects on the inner membrane were observed as a result of these treatments. The use of negative staining to study morphological changes was discussed. It was considered an unsuitable technique due to the large amount of damage done to the mitochondria and the small numbers of mitochondria remaining on the grids after processing.

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