Multiplicity reactivation of vaccinia virus particles treated with nitrogen mustard

The nitrogen mustard bis(beta-chloroethyl)methylamine, a radiomimetic alkylating agent, is known for its ability to inactivate viruses in general and poxvirus in particular. These experiments show that vaccinia virus is rapidly inactivated by it. They show, in addition, that the treated virus exhibits multiplicity reactivation in L cells, closely resembling that experienced with the same virus after exposure to ultraviolet rays. These findings have come from observations of plaque titer, on the one hand, and virus particle aggregation (measured in the electron microscope), on the other. The titer of the treated virus is very sensitive to particle aggregation, increasing and decreasing in a reversible manner as the degree of clumping among the particles is changed. The magnitude of these changes is such that they must be considered in any situation involving plaque assay of the fraction of virus surviving treatment with nitrogen mustard.

Electron microscopy of monkey kidney cell cultures infected with rubella virus

Two rubella virus strains isolated in this laboratory were investigated in terms of their growth in LLC-MK(2) cell cultures and their effect on cell morphology. Rubella virus grew readily in LLC-MK(2) cells, but cytopathic effects of the virus were not observed in infected cultures. Such infected cultures can be subcultured indefinitely and continue to shed virus. Examination of rubella-infected cell cultures by electron microscopy showed the presence of annulate lamellae in the cytoplasm of 15% of the cells. No changes were evident in the nuclei. These membranous inclusions varied in complexity from parallel arrays of annulate lamellae to large lamellar structures of complex morphology. An occasional cell contained a crystal lattice structure in association with the lamellae. Larger inclusions, consisting of disorganized arrays of "unit" membranes, were also found. Uninfected cells were devoid of annulate lamellae, crystals, and complex membranous inclusions. No viruslike particles were observed in any part of the cells from infected cultures. The significance of the structures observed has not been determined.

Physical properties of human Mycoplasma species

Kim, Kwang S. (University of North Carolina, Chapel Hill), Wallace A. Clyde, Jr., and Floyd W. Denny. Physical properties of human mycoplasma species. J. Bacteriol. 92:214-219. 1966.-Studies were made of the comparative morphology and stability of five Mycoplasma species of human origin (M. hominis type 1, M. salivarium, M. fermentans, M. pneumoniae, M. pharyngis). Broth-cultivated organisms were examined by electron microscopy to determine their relative appearance after uniform processing, including fixation-drying with formaldehyde vapor. M. pneumoniae was characterized by the occurrence of 250- to 300-mmu spheres in clusters, and M. pharyngis by the appearance of filaments 120 mmu by 1.5 to 8 mu; the remaining species revealed a variety of structures, including spheres, rings, and short filaments. To complement these findings, the effect of physical stresses on viability of the mycoplasmas was measured by exposing the organisms to heat (in saline), osmotic variations (in sucrose), and sonic oscillation and repetitive freeze-thawing (in culture medium). M. pneumoniae was most resistant to heat, vibration, and freeze-thawing; M. pharyngis was most sensitive to heart and vibration, but was least affected by osmotic changes. The remaining organisms assumed intermediate positions. The type-related variations in relative morphology and stability suggest differing physical attributes of the mycoplasmas studied, supporting taxonomic differentiation of the five species based on metabolic and immunological criteria.

Effect of dietary pectin, protopectin and gum arabic on cholesterol excretion in rats

The addition of pectin and a protopectin preparation containing galactose and arabinose to a noncholesterol-containing basal diet increased the fecal excretion of saponifiable lipids; the absorption of endogenous cholesterol and the excretion of nonsaponifiable lipids were uninfluenced. The addition of pectin to a basal diet containing cholesterol increased the excretion of fecal saponifiable and nonsaponifiable lipids and decreased the absorption of exogenous cholesterol. The addition of the protopectin preparation to the same diet had no significant effect on the excretion of saponifiable lipids, but the excretion of cholesterol was decidely reduced and, in two experiments out of three, there occurred an approximately equivalent increase in noncholesterol nonsaponifiable material. The addition of gum arabic or arabinose to this ration produced practically no changes in the amount of saponifiable and nonsaponifiable fecal lipids and in the recovery of exogenous cholesterol in the feces. Only very small quantities of noncolor-developing sterols were eliminated either on the cholesterol basal diet or when this diet was supplemented with pectin, protopectin, gum arabic or arabinose.

Electron microscopic and physicochemical analysis of a reo-like virus of the planthopper Peregrinus maidis

A virus, determined to be a member of the Reoviridae, was found naturally infecting colonies of Peregrinus maidis, the maize planthopper. The virus, referred to as peregrinus maidis-virus (PgMV), was found by electron microscopy throughout all P. maidis tissues examined, including salivary glands, testes, ovaries, and intestines. The virus particles were associated with fibrillar viroplasmic inclusions in the cytoplasm, of a type characteristic of the Reoviridae. The particles, purified from P. maidis, had morphologies typical of the Reoviridae, with a mean diameter of 68.7 nm. The purified virus contained 12 double-stranded (ds)RNAs, while dsRNA extracts of PgMV-infected P. maidis showed these, plus one additional high-molecular weight dsRNA. No similar dsRNAs were present in extracts of another planthopper. Perkinsiella saccharicida, the corn leafhopper (Dalbulus maidis), or from Zea mays upon which the P. maidis had been reared. Six major and four minor proteins were identified in purified PgMV preparations, but we were unable to determine which of these were definitely of viral or host origin. PgMV was found to be serologically unrelated to three other members of the Reoviridae. The similarities of PgMV to other members of the Reoviridae are discussed.