ANALYSIS OF AUGUST RAT LIVER FOR CALCIUM, COPPER, IRON, MAGNESIUM, MANGANESE, MOLYBDENUM, POTASSIUM, SODIUM AND ZINC

The concentrations of Ca, Cu, Fe, Mg, Mn, Mo, K, Na and Zn in “August” pure line rat livers has been determined by emission spectroscopy, polarography and flame photometry. Differences were shown to exist between normal, regenerating and neoplastic livers, especially in their calcium, iron and manganese contents.

ISOLATION AND PROPERTIES OF INTACT MITOCHONDRIA FROM SPHEROPLASTS OF YEAST

Duell, E. A. (Western Reserve University, Cleveland, Ohio), Sakae Inoue, and Merton F. Utter. Isolation and properties of intact mitochondria from spheroplasts of yeast. J. Bacteriol. 88:1762-1773. 1964.-Functionally intact mitochondria can be obtained in good yields by osmotic disruption of spheroplasts formed from yeast by treatment with an enzyme mixture from the snail digestive tract. The useful range of this method is extended greatly by pretreatment of the yeast cells with 2-mercaptoethylamine and ethylene-diaminetetraacetate. The concentration of the yeast suspension can be increased greatly, the incubation period can be shortened considerably, and the requirement for log-phase cells is obviated. Mitochondria prepared by this method have been compared with those obtained by mechanical disruption in terms of respiratory control, specific activity on a wide range of oxidizable substrates, heterogeneity during centrifugation, and structures observed by electron microscopy. In all cases, the mitochondria obtained from spheroplasts appear to be much less damaged by the preparative procedures.

BRAIN MITOCHONDRIA. I. ISOLATION OF BOVINE BRAIN MITOCHONDRIA

Two methods of preparing a mitochondrial fraction from beef brain cortex are described. Data are presented on the rate of oxidation of substrates, P/O and respiratory control ratios, cholinesterase activity, and DNA content. Electron micrographs of isolated mitochondria and mitochondria in situ are shown. Comparisons are drawn between these preparations and mitochondria prepared in 0.25 M sucrose. The data on enzymic properties and contamination by non-mitochondrial material indicate that mitochondrial fractions which compare favorably with those from other tissues can be prepared from brain tissue.

THE ESTIMATION OF THE OXIDIZED AND REDUCED FORMS OF THE NICOTINAMIDE NUCLEOTIDES

1. A method is described for the determination of the oxidized and reduced forms of the nicotinamide nucleotides by measuring the rate of the oxygen uptake with an oxygen electrode in a system in which the nucleotide acts as the rate-limiting carrier in a cyclic system. 2. The method permits the measurement of quantities as low as 0.02mug. of NAD(+) or NADH or 0.01mug. of NADP(+) or NADPH. 3. The method permits the measurement of the nucleotides in extracts that contain non-specific reducing substances, coloured compounds or fluorescent materials, e.g. green leaves. 4. The results obtained by the present method are compared with those reported in the literature.

ENERGY SUPPLY FOR THE CHEMOAUTOTROPH FERROBACILLUS FERROOXIDANS

Dugan, Patrick R. (Syracuse University, Syracuse, N.Y.), and Donald G. Lundgren. Energy supply for the chemoautotroph Ferrobacillus ferrooxidans. J. Bacteriol. 89:825-834. 1965.-A working model is proposed to explain dissimilatory ferrous iron oxidation by Ferrobacillus ferrooxidans, that is, oxidation linked to an energy source. The model is supported by experimental evidence reported here as well as in the literature. Polarographic assays of the culture medium demonstrated an iron "complex" involving oxygen. The initial "complex" would be oxygenated, but not oxidized because no electron transport has taken place. The "complex" is formed in solution or on the cell surface and is somehow reacted with iron oxidase (or oxygenase), resulting in the release of an electron. Either sulfate or a flavoprotein is suggested as involved in the initial electron-transfer link between iron and the cell. The electron is transported in the cell through a typical electron-transport system involving coenzyme Q(6), cytochrome c, and cytochrome a; oxygen is the final electron acceptor. Electron micrographs of intact and sectioned cells are included to show structural detail in support of the model.

LYSOSOMAL FRACTIONS FROM TRANSITIONAL EPITHELIUM

Histochemical data suggested that the so called lipoid granules of transitional epithelium in some species are equivalent to lysosomes. Scrapings of bovine and canine transitional epithelium were subjected to differential centrifugation to confirm this identification biochemically. Fractions of rat liver, the classic source of lysosomes, were also prepared by the same methods to compare with the fractions obtained from urinary epithelium. In contrast to rat liver, uroepithelial fractions with a high relative specific activity for hydrolases were sedimented before the heavy mitochondria. Microscopically, these fractions contained the highest proportion of lipoid granules. The size and sedimentation characteristics of lysosomes from transitional epithelium more closely resembled those of lysosomes derived from rat kidney than those isolated from liver.