Properties of purified colchicine-binding protein from a cultured carrot cell extract

Colchicine-binding protein (CBP) was purified from a cultured carrot cell extract by DEAE-Sephacel, phosphocellulose and Sephadex G200 column chromatographies. The purified CBP separated into three bands on SDS-polyacrylamide gel electrophoresis. One of them reacted with a monoclonal antibody against chick brain alpha-tubulin and the other two with that against beta-tubulin. Colchicine-binding activity of the purified protein was enhanced by tartrate and inhibited little by an excess of podophyllotoxin. It decayed following first order kinetics, but was more stable than the CBP in the crude extract. The binding constant of the purified CBP for colchicine was 0.57 microM-1 and the number of binding sites of colchicine per mg protein was about 2 nmol. This binding constant is about ten times lower than that of porcine brain tubulin under identical conditions.     

D-2 dopamine receptors in the frontal cortex of rat and human

D-2 dopamine receptors and serotonin receptors in the frontal cortex of rat and human were labelled with 3H-spiroperidol. The D-2 receptors were then distinguished in 4 ways. Dissociation of spiroperidol was biphasic, indicating two populations of sites. Cinanserin in competition with 3H-spiroperidol exhibited high (75%) and low (25%) affinity sites. Dopamine and LY 141865 in competition with 1.25 nM 3H-spiroperidol exhibited high (20-25%) and low (80-75%) affinity sites in the absence of cinanserin, while in the presence of 300 nM cinanserin only the high affinity sites remained. Lesioning of the dopaminergic meso-cortical pathway increased the number of cinanserin-resistant sites by 26%. Thus 3H-spiroperidol binding in the presence of cinanserin can be used to selectively label D-2 receptors in the frontal cortex.     

Effect of a Cloned DNA Fragment from Streptomyces chrysomallusNo. 2 on the Metabolism of Certain Streptomyces Strains

The effects on a cloned DNA fragment carrying an actinomycin resistance determinant on physiological processes in strains of streptomycetes with various potencies in producing this antibiotic, their inactive mutants, and the model strain ofStreptomyces lividans66 were studied. This fragment was shown to modulate bacterial resistance to actinomycin and biosynthesis of antibiotics.     

Construction of a human cytochrome c gene and its functional expression in Saccharomyces cerevisiae

The nucleotide sequences of a partial cDNA and three pseudogenes of human cytochrome c were determined. The complete nucleotide sequences which encode human cytochrome c were constructed on the basis of one of the pseudogenes by in vitro mutagenesis. The constructed human cytochrome c was functionally expressed in Saccharomyces cerevisiae. The recombinant human cytochrome c was purified and characterized.     

DIFFERENTIAL INCORPORATION OF [3H]LYSINE INTO VISUAL CORTEX PROTEIN FRACTIONS DURING FIRST EXPOSURE TO LIGHT

—A resolution of the enhancement of protein synthesis in the visual cortex of rats during first exposure to light (Richardson and Rose , 1972) was achieved by polyacrylamide gel electrophoresis using a double-labelling technique. Differential incorporation of lysine was established between exposed and control animals in two fractions of the soluble proteins and seven fractions of the insoluble proteins. This suggests that exposure to a new experience of this type involves a specific effect on protein synthesis, rather than a general stimulation across all fractions.     

Activated lymphocytes trigger lymphoblast extravasation.

Intraperitoneal stimulation of adoptively sensitized rats with bacterial antigen promotes the localization of lymphoblasts at the site of antigen deposition. Lymphoblast extravasation activity (LEA) is generated only when specifically immune donor lymphocytes and the recipients of these cells share at least on Ag-B haplotype. However, if the specificity criteria for its formation are satisfied, LEA promotes the local development of lymphoblasts of all available specificities and irrespective of their Ag-B genotype. Allogeneic lymphoblasts do not participate actively in the delayed inflammatory reaction even when they are passively recruited into exudates. The results suggest that LEA is a T cell-derived mediator that amplifies the delayed type hypersensitivity reaction by directing recently activated lymphocytes into lesions.