NAD-dependent formate dehydrogenase from methylotrophic bacteria. Isolation and properties]

NAD-Dependent formate dehydrogenase (FDH) has been isolated from methylotrophyc strain Bacterium sp 1 by (NH4)2SO4 fractionation of cell extract, ion-exchange chromatography and preparative isotachophoresis. Preparation of FDH is homogeneous in analytical polyacrylamide gel electrophoresis and under ultracentrifugation. Sedimentation coefficient of FDH is 4.9S. Mikhaelis constants are 1.1-10(-4) M for NAD and 1.5-10(-2) M for formate. In the absence of sulfhydril compounds FDH is unstable, but it is stable in the presence of mercaptoethanol or ditiotreitol.     

Increased affinity of liposomes derived from total spleen and liver lipids to spleen cells

The interaction of liposomes derived from total lipids of mouse spleen and liver with mouse spleen cells was studied. It was shown that the binding of these liposomes is much higher than the binding of liposomes obtained from a model lipid mixture--phosphatidylcholine--phosphatidylethanolamine--cholesterol (2:1:1). Adherent and nonadherent spleen cells were found to have affinity for liposomes derived from total lipids of spleen or liver. Removal of gangliosides and protein contaminants from the liposomes derived from total spleen lipids caused an increased binding of liposomes to spleen cells. Multilamellar liposomes bound more effectively to ultrasonicated vesicles having a homologous lipid composition than the liposomes with a different lipid composition. The increased affinity of liposomes derived from total lipids of spleen or liver for spleen cells may account for the identical fluidity of the lipid bilayer of liposomes and plasma membranes of spleen cells.     

Ribosomal assembly deficiency in an Escherichia coli thermosensitive mutant having an altered L24 ribosomal protein.

Localized P1 mutagenesis was used to screen for conditionally lethal mutations in ribosomal protein genes. One such mutation, 2859mis, has been mapped inside the ribosomal protein gene cluster at 72 minutes on the Escherichia coli chromosome and cotransduces at 98% with rpsE (S5). The 2869mis mutation leads to thermosensitivity and impaired assembly in vivo of 50 S ribosomal particles at 42 °C. The strain carrying the mutation has an altered L24 ribosomal protein which at 42 °C shows weaker affinity for 23 S RNA than the wild-type protein. The mutational alteration involves a replacement of glycine by aspartic acid in protein L24 from the mutant. We conclude therefore that the 2859mis mutation affects the structural gene for protein L24 (rplX).     

Adrenoreception characteristics of the neurons of the superior cervical and caudal mesenteric sympathetic ganglia of the cat]

Experiments were conducted on the supeior cervical and the caudal mesenteric sympathetic ganglia of a cat; it was shown that dophamine (DA), similarly to noradrenaline (NA) and adrenaline (A), depressed the cholinergic conduction. The activity of DA in the superior sympathetic ganglion was less than that of the NA and A 2- and 3-fold, respectively, and in the caudal mesenteric ganglia DA was 50 times more active than NA by the capacity to depress the cholinergic conduction. The effects of DA and NA in the superior cervical ganglia were eliminated by dyhydroergotamine, phentholamine and haloperidol, but not by tropaphen and chlorpormazine. In the caudal mesenteric ganglia the inhibitory effect of NA was decreased by phentholamine, dihydroergotamine and chlorpromazine, but not by haloperidol. On the contrary, haloperidol and chlorpromzine decreased the depressive effect of DA on the cholinergic conduction in the caudal mesenteric ganglion, whereas phentholamine, dihydroergotamine and deseryl proved to be ineffective. It is supposed that the manifestation of the dopaminergic mechanism of inhibition of cholinergic conduction in the caudal mesenteric sympathetic ganglion could underlie the dilatation of the mesenterial and renal vessels and its hypotensive action caused by DA.