No abstract

The distribution of viral ribonucleic acid (RNA) on various cell membrane fractions derived from a porcine kidney cell line infected with Japanese encephalitis virus was investigated. At 40 h postinfection, after virus growth had reached its peak, three viral RNAs, 45S, 27S, and 20S, were associated with the cytoplasmic membranes and intact nuclei. The amount of each RNA associated with the nucleus was two-to fivefold greater than that present with the cytoplasmic membranes. Treatment of washed infected nuclei with 1.0% Triton X-100, which removed the outer nuclear envelope membrane, also removed the viral RNA. When the nucleus was fractionated into nuclear envelope membranes and a large particle fraction which sedimented at 600 x g, nearly all of the viral RNA remained associated with the envelope membranes. The nuclear envelope membranes contained higher viral RNA polymerase activity than the cytoplasmic membranes derived from the same cells. These data suggest that major sites for Japanese encephalitis virus RNA synthesis may be localized on or in very close association with the nuclear envelope membranes.

The coagulae-positive staphylococci comprise a very homogeneous, readily identifiable species (Evans and Niven, 1950; Shaw et al., 1951) that includes all of the proven pathogenic and enterotoxin-producing strains of staphylococci. As a result of the clinical and public health significance of these organisms, a selective medium for their isolation and enumeration would have considerable value. Chapman (1945, 1946, 1948) has proposed several media that are selective for staphylococci and have some value in differentiating between coagulase-positive and coagulase-negative strains. The selective action of these media is based on a high sodium chloride content and the use of mannitol as an energy source. Their differential value is based on orange pigmentation, acid production from mannitol, and gelatin hydrolysis by coagulase-positive strains. However, not all such strains have these characteristics, and numerous coagulase-negative strains posse some or all of these characteristics. Thus it is frequently necesary to isolate a considerable number of pure cultures from these media and apply the coagulase test to these isolates. A more selective medium has been proposed by Ludlam (1949). This medium includes tellurite and lithium chloride as selective agents and the pH of the medium was adjusted to 9.6 before sterilizing. This medium was found to be quite satisfactory for the isolation of coagulasepositive staphylococci from air, skin surfaces, the nose, and stool specimens (