Presence of rhapidosomes in various species of bacteria and their morphological characteristics

Rod-shaped structures have been observed in cells of Pseudomonas, Photobacterium, Proteus, and Saprospira by use of the negative-contrast stain. These structures, referred to as rhapidosomes, appear to be normal components of these cells. Other bacteria including Escherichia, Salmonella, Shigella, Klebsiella, Micrococcus, Bacillus, Mycobacterium, Rhodospirillum, and Hydrogenomonas genera failed to reveal these structures. The rhapidosomes of Saprospira were found to consist of two rods, one encasing a narrower, longer structure. In contrast, the rhapidosomes of Pseudomonas, Proteus, and Photobacterium were without the rigid inner structure, but were occasionally seen filled with a homogeneous material as observed by the negative stain. Ultrathin sections of Pseudomonas cells indicate that these rhapidosomes are embedded within or are in close association with the nucleoplasm.

The effect of ion concentration and pH on the thermal stability of a canine adenovirus

The inactivation of a canine adenovirus hemagglutinin and infectivity at 56 °C at varying times up to 1 h has been studied in the presence of various ions and concentrations of ions.Under conditions of uncontrolled pH 1–2 M NaCl and MgCl2 both stabilized the virus hemagglutinin and infectivity. Lower concentrations of these salts as well as 0.04 M phosphate, Hank's balanced salt solution, and minimal Eagle's medium had little stabilizing effect. Molar concentrations of phosphate and Tris butter were also found to stabilize the virus hemagglutinin.The pH adjustment of the suspending salt solution was found to be important since high concentrations of salts such as MgCl2 are quite acidic. Both 1 M MgCl2 and 1 M NaCl stabilized the virus in the pH range of 4–6, but inactivation was rapid at pH 3 and less rapid at pH 7. Ion concentrations lower than 1 M markedly reduced the hemagglutinin stabilization at optimun pH.