The Distribution of Nickel, Copper, Zinc, and Iron in Tree Leaves

The distributions of nickel, copper, zinc, and iron in freshleaves from four tree species were studied using differentialoentrifugation of cell homogenates to fractionate the cell organellesand atomic absorption spectrophotometry to measure the concentrationsin the various fractions. Results from each species were closelysimilar. Approximately 90 per cent of the nickel was presentin the supernatant fraction while approximately 80 per centof the iron was present in the chloroplast fraction. Both copperand zinc had subcellular distributions similar to one anotherand contained appreciable amounts of the elements in both chloroplastand supernatant fractions. High-voltage paper electrophoretic separations of the solubleextracts of leaves showed that while copper, zinc, and ironexisted principally as anionic complexes, nickel existed asa cationio species. It was considered that this cationic formof nickel was unlikely to be an unchelated aquated cation.     

The Physiology of Astrephomene gubernaculifera1

SYNOPSIS. A comparative physiologic study of 4- and 7-chromosome strains of Astrephomene gubernaculifera was done. The vitamins p-aminobenzoic acid, nicotinamide, biotin, thiamin HCl and vitamin B₁₂ were tested for their ability to support growth. Only vitamin B₁₂ was required for active growth altho the presence of thiamin HCl was necessary to produce structurally typical colonies. Astrephomene will not grow in the absence of an exogenous source of carbon. Of the 36 carbon sources tested, only pyruvate, butyrate, succinate and acetate permitted active growth. Sodium acetate was the best. Strains grew within the initial pH range of 5.0–7.5. At pH values above 8.0 growth declined rapidly. When media were buffered with TES (N-tris [hydroxymethyl]methyl-2-aminoethane-sulfonic acid) at an initial pH of 6.8 growth was enhanced. The organism grew at 15–40 C. Growth in the dark was slightly less than that in the light.     

Constant Production of Type C Virus Particles in a Continuous Tissue Culture derived from Pleural Effusion Cells of a Lymphoma Patient

PARTICLES resembling viruses were first observed in organs of mice with spontaneous leukaemia and in thin sections of a biopsy specimen from a lymph node of a patient with acute lymphocytic leukaemia by Dmochowski and Grey¹. They also found them in some biopsy specimens of lymph nodes and bone marrows before and after growth in tissue culture^2,3,8. Recent reports have described the presence of type C virus particles in other human tumours including liposarcoma⁴, osteosarcoma^5,6, giant cell tumour⁹, rhabdomyosarcoma (unpublished results of L. D. and E. S. P.) and breast carcinoma⁷.