Diminished Reovirus Capsid Stability Alters Disease Pathogenesis and Littermate Transmission

Reovirus is a nonenveloped mammalian virus that provides a useful model system for studies of viral infections in the young. Following internalization into host cells, the outermost capsid of reovirus virions is removed by endosomal cathepsin proteases. Determinants of capsid disassembly kinetics reside in the viral σ3 protein. However, the contribution of capsid stability to reovirus-induced disease is unknown. In this study, we found that mice inoculated intramuscularly with a serotype 3 reovirus containing σ3-Y354H, a mutation that reduces viral capsid stability, succumbed at a higher rate than those infected with wild-type virus. At early times after inoculation, σ3-Y354H virus reached higher titers than wild-type virus at several sites within the host. Animals inoculated perorally with a serotype 1 reassortant reovirus containing σ3-Y354H developed exaggerated myocarditis accompanied by elaboration of pro-inflammatory cytokines. Surprisingly, unchallenged littermates of mice infected with σ3-Y354H virus displayed higher titers in the intestine, heart, and brain than littermates of mice inoculated with wild-type virus. Together, these findings suggest that diminished capsid stability enhances reovirus replication, dissemination, lethality, and host-to-host spread, establishing a new virulence determinant for nonenveloped viruses.     

Scapular correlates of muscle morphology in Papio cynocephalus.

The scapula responds to the compressive states of its surrounding matrix produced by muscle functioning and weight bearing in the upper extremity with discernible structural correlates. These structural correlates can be utilized to infer locomotor behavior. After dissection and drying, the weights of several muscles of the shoulder region of 11 adult female baboons (Papio cynocephalus) were statistically compared to various dimensions of the bony scapula. A significant correlation was obtained between the weights of the individual compressive muscles, the combined weights of the compressive muscles and a scapular dimension of width. A nonsignificant correlation between these muscles and a sscapular dimension of length was also found. The results of this study were compared to those of a previous study of the scapular musculature in Macaca and opposing conclusions were obtained. The advisability of lumping macaques and baboons into a single gross locomotor category is rejected.     

Identification of a complex of the three forms of the rat liver asialoglycoprotein receptor

We have generated antibodies against synthetic peptides which represent the carboxyl terminus of either the major, or the two minor, forms of the rat hepatic lectin which recognizes galactose-terminated glycoproteins (asialoglycoproteins). The antibodies were shown to be specific for the form of the lectin containing the immunizing peptide sequence by the following: reaction with purified lectin after sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoprecipitation of sodium dodecyl sulfate-denatured lectin, immunoprecipitation of lectin synthesized in vitro. These antibodies, however, precipitated all three rat hepatic lectin forms from nonionic detergent extracts of hepatocytes labeled with 125I via the lactoperoxidase catalyzed technique. A similar result was obtained if antibody was bound to intact cells prior to solubilization with detergent and collection of the immune complexes. We conclude that at least the plasma membrane-associated fraction of the rat hepatic lectin forms exists as a heterotypic complex.     

Speciation and the evolution of behaviour in prosimians

A mechanism is suggested, based on a biphasic approach-withdrawal theory proposed byT. C. Schneirla, to account for how behaviours may be selected by environmental forces for transmission over generations. The basic postulates of Schneirla's theory are presented followed by an examination of some aspects of lorisid behaviour in the light of this theory.     

Dose dependent radiation-induced hypotension in the canine

Radiation-induced early transient incapacitation (ETI) is often accompanied by severe systemic hypotension. However, postradiation hypotension does not occur with equal frequency in all species and is not reported with consistency in the canine. In an attempt to clarify the differences in reported canine postradiation blood pressures, canine systemic blood pressures were determined both before and after exposure to gamma radiation of either 80 Gy or 100 Gy. Data obtained from six sham-radiated beagles and 12 radiated beagles indicated that 100 Gy, whole-body, gamma radiation produced a decrease in systemic mean blood pressure while 80 Gy, whole-body, gamma radiation did not. Analysis of this data could be consistent with a quantal response to a gamma radiation dose between 80 Gy and 100 Gy.     

Effect of trypsin on the cell surface proteins of hepatoma tissue culture cells. Characterization of a carbohydrate-rich glycopeptide released from a calcium binding membrane glycoprotein.

Concentrations of trypsin that bring about aggregation of hepatoma tissue culture (HTC) cells also release from the cell surface an Mr = 55,000 glycopeptide fragment. This glycopeptide fragment also accumulates in the medium, including serum-free medium, as a normal consequence of membrane protein turnover. The trypsin-released glycopeptide is labeled when cells are grown in the presence of fucose or leucine before treatment of the cells with the protease. Similarly, the glycopeptide fragment can be labeled by reacting cells in situ by lactoperoxidase-catalyzed radioiodination or by tritiated borohydride reduction of cells treated first with neuraminidase and galactose oxidase. The tryptic glycopeptide fragment was purified by concanavalin A-Sepharose chromatography, and hydroxyapatite chromatography in the presence of dodecyl sulfate. The amino acid and carbohydrate composition was determined, as was the sensitivity of the purified glycopeptide to a variety of endo- and exoglycosidases. The purified glycopeptide contains an average of 17 sialic acid residues and hence, shows charge heterogeneity after electrophoresis in isoelectric focusing gels. The charge heterogeneity can be eliminated completely by treatment with neuraminidase. The glycopeptide after this treatment is homogeneous. The trypsin-sensitive membrane glycoprotein which is the source of the Mr = 55,000 glycopeptide was identified by two-dimensional gel electrophoretic analysis of labeled cells, treated or not treated with trypsin. This glycoprotein, which has an apparent molecular weight of 85,000 and forms a homodimer in the presence of calcium ions, was purified and its identity as the parent of the Mr = 55,000 glycopeptide was confirmed by showing that the same Mr = 55,000 fragment was released by trypsin from the purified glycoprotein as was released from the intact cells.