Proteins specified by African swine fever virus. I. Analysis of viral structural proteins and antigenic properties

At least 28 polypeptides have been identified in intracellular virus, with molecular weights ranging from 11,500 to 243,000 daltons. By treatment with Nonidet P-40 and 2-mercaptoethanol it is possible to obtain subviral particles that have lost some proteins and have a density in CsCl of 1.31 g/cm3 which is higher than that of the complete virus (1.23 g/cm3). After addition of NaCL the virus loses its major protein VP73 which indicates that it is localized in the viral envelope. Cores obtained after this treatment are made up of at least 14 proteins. Incorporation of 3H-fucose and 3H-glucosamine in intracellular virus occurs in three minor components. The protein VP42 is possibly the cell actin and appears to be strongly associated with the virus. It is not possible to eliminate it under conditions where the viral envelopes disappear morphologically. At least the proteins VP172, VP162, VP146 and VP73 act as antigens in the natural infection.

Subunit interactions and immobilised dimers of human liver arginase

Incubation of soluble human liver arginase (L-arginine amidinohydrolase, EC 3.5.3.1) with p-hydroxymercuribenzoate resulted in the dissociation of the enzyme into active dimers. Addition of 2-mercaptoethanol resulted in the regeneration of the tetrameric enzyme. When arginase, bound covalently to nylon, was incubated with p-hydroxymercuribenzoate, matrix-bound dimers were obtained. Incubation of these species with 2-mercaptoethanol resulted in stable, unmodified dimers. Based on this dissociation of arginase, a model with D2-symmetry is suggested for this enzyme. The specific activity, the Km value for arginine, pH optimum and the inhibition constants for ornithine and lysine were determined for monomeric, dimeric and tetrameric forms. It is concluded that the behaviour of the active sites of the monomers is not substantially altered by the interaction of these species in the oligomeric molecule.

Scanning electron microscopic investigations of olfactory epithelium in the chick embryo

This paper describes maturation of the surface of the olfactory epithelium of the superior nasal concha of chick embryos from the seventh day of incubation till hatching. From the earliest stages investigated onward, the apical surface of the olfactory epithelium is characterized by variability in the number and configuration of surface protrusions. The growth of olfactory cilia is described and the significance of regional differences in their density is discussed in relation to regional variations in the sensitivity of the epithelium to odorants. The maturation of the respiratory epithelium covering the inferior nasal concha is also described.

The penetration of sodium into the epithelium of the frog skin

The aim of this paper is twofold. First, to describe a method for the measurement of the unidirectional flux of Na from the outer bathing solution into epithelium (J(OT)), and second, to describe the use of this method under a variety of experimental conditions in order to obtain some insight into the nature of this flux. The method developed is based on the exposure of a frog skin to a Ringer solution containing (22)Na. The exposure is made so that neighboring points along the surface remain in contact with the (22)Na solution for gradually longer periods, ranging from 0 to 46 sec. Some 8 to 10 samples of the exposed part are used to obtain the time course of the uptake of (22)Na and this time course is used, in turn, to evaluate J(OT). This flux is then studied in skins mounted between two identical Ringer solutions with 115 mM Na (11.25 +/- 0.10 [18] micromole.hr(-2) cm(-2)), and in skins mounted with Ringer with 1 mM Na on the outside and 115 mM Na on the inside (0.43 +/- 0.05 [18] micromole.hr(-1).cm(-2). From the observations that the flux is much larger than the net Na flux across the whole skin, that it is inhibited by K(+), and is unaffected by ouabain, it is concluded that the penetration of Na(+) into the epithelium does not occur by simple diffusion and is not directly dependent on an ouabain-sensitive mechanism. In the course of these experiments it was observed that when the skin was crushed between two chambers the uptake of Na in the neighboring exposed areas was decreased.