The process of fixation of DNA-containing plasms is investigated by macroscopical and electron microscopical observations on solutions of DNA, nucleohistones, as well as on bacterial nuclei. The following treatments were found to produce a gelation of a solution of DNA or nucleohistones: (a) OsO(4) fixation at pH 6 in the presence of amino acids (tryptone) and Ca(++). (b) Exposure to aqueous so...

Better understanding of uranyl toxicity in bacteria is necessary to optimize strains for bioremediation purposes or for using bacteria as biodetectors for bioavailable uranyl. In this study, after different steps of optimization, Escherichia coli cells were exposed to uranyl at low pH to minimize uranyl precipitation and to increase its bioavailability. Bacteria were adapted to mid acidic pH be...

The role of renal hemodynamic alterations in the curtailment of renal function was studied in rabbits with uranyl acetate-induced acute renal failure. The day following the i.v. injection of uranyl acetate (2 mg/kg of body wt), renal blood flow (RBF) and clearance of creatinine (Ccr) decreased to approximately 60 and 20% of controls, respectively. Intracortical fractional flow distribution, est...

Two electron microscopic staining techniques, one using tannic acid-glutaraldehyde as a fixative, and the other using tannic acid-uranyl acetate solution as a stain on ultra-thin sections of glutaraldehyde fixed material, were directly compared for elastic fibre staining on several human and animal tissues. Various concentrations of tannic acid were compared using both techniques. The two techn...

To study the effect of EDTA on cell wall structure and the reversal of this effect by uranyl ion, thin sections of pea root tips were examined in the electron microscope. EDTA is known to facilitate separation of the cells in root tips. When sections of fixed and embedded EDTA-treated roots are floated on a uranyl-acetate solution, a loose network is revealed that would seem to be cellulose. In...

A three-dimensional model of the Escherichia coli 30 S ribosome has been derived from an extensive dark field electron microscopic investigation of unstained and unshadowed ribosomes. Subsequent studies of specimens lightly stained with uranyl acetate have added information on the location of regions that preferentially bind uranyl ions and may represent surface RNA. The model is an elongated c...