Coordinate repression of arginine aminopeptidase and three enzymes of the arginine deiminase pathway in Streptococcus mitis

Streptococcus mitis contains two arginine aminopeptidases (I and II) as an arginine-supplying system and the arginine deiminase pathway as an arginine-utilizing system. The levels of arginine aminopeptidase I and three enzymes of the arginine deiminase pathway were suppressed by glucose in an apparently coordinate manner. Enzyme II appeared to be constitutive.     

Suppressive effect of elcatonin, an eel calcitonin analogue, on excessive urinary hydroxyproline excretion in polyostotic fibrous dysplasia (McCune-Albright's syndrome)

A 12-year-old Japanese girl with polyostotic fibrous dysplasia and endocrine concomitants, was treated with elcatonin, a synthetic eel calcitonin analogue, 10 MRC unit/twice a week given by intramuscular injection. Significant decreases in 24 hr urinary content of hydroxyproline and other amino acids from bone collagen were observed during the course of treatment over 5 months. This biochemical result suggests that the synthetic eel calcitonin analogue exhibits the therapeutic effect in patients with polyostotic fibrous dysplasia by inhibiting bone resorption.     

Uptake of liposome-encapsulating plasmid DNA by plant protoplasts and molecular fate of foreign DNA

Summary Conditions faborable for the uptake of artificial lipid vesicles (liposomes) encapsulating plasmid DNA byDaucus carota protoplasts were investigated. Incubation period necessary for the maximum uptake of liposome-DNA was in the neighborhood of 10 minutes under the circumstances where liposomes (approximately 1.28 moles lecithin/ml) were mixed with 5 × 10⁶ protoplasts/ml. Results obtained by Southern hybridization indicated that the recombinant DNA vector, pBR325 was found in protoplasts after 20 hours incubation in the open circular, linear and some complexed forms. There were some variations in DNA-uptake among protoplasts from different plant species. The gradual disappearance of plasmid molecules was confirmed after 1 week culture, suggesting instability of pBR325 in prolonged cell culture.     

Distinction of two subtypes of human leukocyte interferon (IFN-alpha) on B cell activation. B cell proliferation by two subtypes of IFN-alpha

We examined the effect of interferon (IFN), with particular emphasis on the effects of the two subtypes of IFN-alpha (IFN-alpha A and IFN-alpha B) on the B cell proliferation induced by Staphylococcus aureus Cowan I bacterium (SpA Col). An increase of SpA Col-induced proliferation was observed in the presence of 100 to 1000 U/ml of IFN-alpha, but a decrease of SpA Col-induced proliferation was observed in the presence of 1000 to 10,000 U/ml of IFN-beta. The two subtypes of IFN-alpha had different effects on cell proliferation; a significant enhancement was shown in the presence of 1000 to 10,000 U/ml of IFN-alpha A, but inhibition was shown in the presence of 1000 to 10,000 U/ml of IFN-alpha B. In the reconstitution test of the two subtypes of IFN-alpha, the boundary between enhancement and inhibition of SpA Col-induced proliferation was revealed when the proportion of IFN-alpha A and IFN-alpha B (IFN-alpha A:IFN-alpha B) ranged between 8:2 and 9:1. Toward the SpA Col-induced responses, the above IFN were all found to act on B cells directly, independent of the presence of T cells. Proliferative responses by IFN-alpha and IFN-alpha A, however, were shown to be slightly dependent on the presence of monocytes. The lymphocyte proliferation induced by other mitogens (phytohemagglutinin, concanavalin A, pokeweed mitogen, and protein A of S. aureus) were all inhibited by the above IFN.     

Chemical modification of cytosine residues of U6 snRNA with hydrogen sulfide (nucleosides and nucleotides. Part 49 [1]).

Sulfhydrolysis of cytosine residues to 4-thiouracil residues in mouse U6 snRNA was carried out to examine the secondary structure of U6 snRNA. The cytosine residues at positions 6, 42 and 68 were modified significantly, and at positions 11, 19 (or/and 25), 61 and 66 in moderate extent. Based on the result, the plausible secondary structure of U6 snRNA is discussed.     

Formation of Recombinants Between Nontransmissible Drug-Resistance Determinants and Transfer Factors

Noninfectious drug-resistance determinants acquired conjugal transmissibility by the formation of recombinants with transfer factors, suggesting the origin of R factors.