Mutual recognition between polymerized liposomes. IV. Polysaccharide-lectin system.

As a model of cell-cell recognition processes, the association processes of a polysaccharide (mannan)-carrying liposome with a lectin (Concanavalin A, Con A)-carrying polymerized liposome were followed by turbidimetry. The association process was strongly inhibited by the addition of a low molecular weight sugar, methyl-alpha-D-mannopyranoside, which shows that the association between the liposomes is due to the specific interaction between Con A and mannan. The association rate constant obtained was much smaller than the theoretical value for a diffusion-controlled binary association process. This implies that the association rate of liposomes is limited by the recognition between complementary ligands bound on the liposome surfaces. Another reason for the smaller association rate constant in the liposome-liposome system is the repulsive hydration effect. The effect of the surface density of the lectin immobilized on the liposome on the recognition was also examined.     

Synthesis of cytochrome c oxidase in the liver of Rana catesbeiana tadpole treated with griseofulvin

The effect of griseofulvin treatment on the synthesis of cytochrome c oxidase was studied with the liver of the tadpole, Rana catesbeiana. (1) In the liver of tadpole treated with griseofulvin, a ferrochelatase inhibitor, the synthesis of heme a, but not cytochrome c oxidase protein, is inhibited. (2) The apocytochrome c oxidase which is formed in the liver of tadpole treated with griseofulvin is converted to the active holoenzyme by exogenously added heme a.     

An epidemiological study of Serratia marcescens infections by bacteriocin typing

Bacteriocin sensitivity typing according to the method of Traub (Appl. Microbiol. 1971. 21: 837-840) was carried out on 226 clinical isolates of Serratia marcescens obtained from inpatients at Nagasaki University Hospital during the period from January 1976 to December 1978. The isolates were divided into 16 different bacteriocin types, mainly 26, 4, and 9. The distribution of the types suggests that Serratia marcescens infections may be caused by cross infection. Reproducibility of bacteriocin typing and the relationship between serotypes (O-antigen) and bacteriocin types are discussed in regard to the application of this method to the study of nosocomial infections.     

Sex difference in susceptibility to teratogenic effect of maternal biotin deficiency in mouse embryos

When pregnant mice were fed biotin-deficient diets, cleft palate occurred more frequently in male fetuses than in female fetuses. Possible underlying mechanisms are speculated on, and some methodological problems in the analysis of sex-related differences in multiparous animals are discussed.     

Existence of a polar digitalis-like factor in mammalian hypothalamus

We were able to partially purify a polar digitalis-like factor from rat and bovine hypothalami based on the capacity to inhibit [3H]ouabain binding to intact human erythrocytes. This factor was characterized in reference to the digitalis-like factor that we have isolated and reported on. Hypothalamic factor shared digitalis-like activities and physicochemical properties with the one derived from human urine and mammalian plasma. These findings strongly suggest that a polar digitalis-like factor identical to the circulatory factor does exist in mammalian hypothalamus.     

Presence of endothelin-1 in porcine spinal cord: isolation and sequence determination

We investigated the molecular forms of endothelin (ET) related peptides in porcine spinal cord by high performance liquid chromatography coupled with radioimmunoassays using three antisera raised against ET-1 and C-terminal fragments of ET-1 and big ET-1. ET-1 and its oxidized form were isolated as major immunoreactive peptides and sequenced. Furthermore, immunoreactivities like ET-3 and big ET-1(22-39) (contents: less than 8% and less than 1% of ET-1, respectively) were detected based on their chromatographic retention times and characteristics of immunoreactivity to the antisera. Big ET-1 was only scarcely detected. Immunohistochemical study showed the presence of ET-1-like immunoreactivity in motoneurons, dorsal horn neurons and dot- and fiber-like structures in the dorsal horn of lumbar spinal cord. These results indicate that ET-1 is present not only in endothelial cells but also in spinal cord, and that big ET-1 is converted into ET-1 in spinal cord by specific processing between Trp21-Val22. The data also indicate that ET-1 may act as a neuropeptide in the central nervous system.     

Cloning of rabbit uricase cDNA reveals a conserved carboxy-terminal tripeptide in three species

cDNA clones encoding uricase have been isolated from a rabbit liver cDNA library. The nucleotide sequences of the cDNAs have been determined and those of the rat uricase cDNA have been revised. In all three uricases, the carboxy-terminal tripeptides are Ser-Arg/Lys-Leu sequences, which have recently been suggested as an essential element of peroxisomal targetting signals for many but not all peroxisomal proteins.     

Chimeric heterosis in mandibular size in mice

Morphometrical observations were carried out on the mandibles of chimeras made from the embryos of C57BL/6 and BALB/c mice to compare with the two strains and their reciprocal F1 crosses. The results of the principal component analysis indicate that the first principal component (PC1) and the second principal component (PC2) extracted might be acceptable as size and shape factors, respectively. Variations of both PC1 and PC2 were generally larger in the chimeras than in the two component strains and their F1 crosses. The mean PC1 value of the chimeras was larger than that of the two component inbred strains, and it was similar to that of F1 crosses, or slightly larger. The overall size of the mandible represented by PC1 tended to be larger in the chimeras consisting of two component cells that were approximately equivalent than in those that shifted to either cell population. The above trend was observed in both sexes. These results indicate that chimeric heterosis due to the interaction between genetically different cells (C57BL/6 and BALB/c) has some relation to mandible size. The mean PC2 value, which was accepted as shape factor, was intermediate between the two inbred strains. The mandible size (PC1) and shape (PC2) were bilaterally symmetrical, except for the shape in the female chimeras and in (C57BL/6 x BALB/c)F1.