Ultrastructural localization of the calcium-binding protein parvalbumin in neurons of the song system of the zebra finch,Poephila guttata

Summary The distribution of parvalbumin (PV) within neurons of the vocal motor nucleus hyperstriatum ventralepars caudalis (HVc) was investigated in the forebrain of adult male zebra finches by means of light and electron microscopy using the indirect immunoperoxidase technique. Parvalbumin-reaction product was located in the amorphous material of perikarya, dendrites and nuclei, and associated to microtubuli, postsynaptic densities and intracellular membranes; it was found in some axons and Gray type-2 boutons, but rarely in type-1 boutons and never in the Golgi apparatus. These observations suggest that parvalbumin may regulate calcium-dependent processes at the postsynaptic membrane and in the cytosol. Furthermore, the partial association of parvalbumin to microtubuli points to an involvement in calcium-dependent tubular functions. Calcium currents and microtubular assembly or transport may be relevant for the known functions of HVc in song learning.     

Composition of Caulobacter crescentus murein synthesized in the presence of glycine

Abstract Glycine added to the growth medium of Caulobacter crescentus was found to substitute Cterminal alanine in the peptide side chains of the murein of this species. Murein synthesized in vivo and in vitro in the presence of glycerine was poorly crosslinked as was new murein formed in the presence of the amino acid. The reduced cross-linkage seems to be due to the effect of glycine on the formation of trimeric muropeptides as revealed by high-performance liquid chromatography (HPLC) muropeptide analysis of murein formed in the presence and absence of the amino acid.     

Regulation of the β-ketoadipate pathway in Rhizobium japonicum and bacteroids by succinate

Rhizobium japonicum 61-A-101 and its bacteroids catabolize phenol and p-hydroxybenzoate. With phenol as a carbon source, utilization started only after a prolonged lag phase while p-hydroxybenzoate was almost instantancously metabolized. Succinate, which supports rapid growth of Rhizobium japonicum, completely repressed respication of phenol; the oxidation of p-hydroxybenzoate was partially inhibited. Pyruvate, supporting slower growth than succinate, retarded the onset of phenol consumption but did not affect its maximum rate.Catabolite repression of phenol utilization by succinate appears to be a characteristic feature of rhizobia. In Pseudomonas putida which also actively metabolizes phenol, succinate had no effect on phenol utilization.     

Molecular cloning of the F8 fimbrial antigen from Escherichia coli

Abstract The genetic determinant coding for the P-specific F8 fimbriae was cloned from the chromosome of the Escherichia coli wild-type strain 2980 (O18:K5:H5:F1C, F8). The F8 determinant was further subcloned into the Pst I site of pBR322 and a restriction map was established. In a Southern hybridization experiment identity between the chromosomally encoded F8 determinant of 2980 and its cloned counterpart was demonstrated. The cloned F8 fimbriae and those of the wild type strain consist of a protein subunit of nearly 20 kDa. F8 fimbriated strains were agglutinated by an F8 polyclonal antiserum, caused mannose-resistant hemagglutination and attached to human uroepithelial cells. The cloned F8 determinant was well expressed in a variety of host strains.     

Guaianolides from Saussurea affinis

Cynaropicrin, 11βH-11,13-dihydrodesacylcynaropicrin, aguerins A and B, isoamberboin and the new guaianolides saussureolide and 11βH-11,13-dihydrodesacylcynaropicrin 8-β-d-glucoside were isolated from Saussurea affinis.     

Inactivation of a newly transferred gene in recombination-deficient recipients of Escherichia coli

Summary The expression of a newly transferred lacZ ⁺ gene in lacZ recipients carrying various mutations in the recA and recB genes was studied by measuring the rates of induced synthesis of -galactosidase in zygotes formed after mating with either F or Hfr donors. The ability to synthesize -galactosidase decreases with time in both recA and recB zygotes when the lacZ ⁺ gene is transferred from an Hfr donor, but not when the lacZ gene is transferred from an F donor. There is no such inactivation of the newly transferred lacZ ⁺ gene in Rec⁺ zygotes. We conclude that the functioning of the transferred DNA is progressively inactivated in rec recipients unless the DNA is contained in an episome such as F.