Functional defects of culture-grown bone marrow-derived macrophages from autoimmune MRL/MpJ-lpr/lpr mice

To investigate the primary defects and development of macrophages in MRL/MpJ-/pr/lpr (MRL/l) mice, we used a pure population of macrophages derived from bone marrow precursor cells cultured in the presence of L-cell conditioned medium (LCM) as a source of colony stimulating factor. Bone marrow-derived macrophages (BMM phi) from MRL/l mice had lower antigen presenting activity as detected by the induction of antigen-specific T cell proliferation, than age- and sex-matched control mice (CBA/J). Cell surface antigens (Ia and Mac-1) were determined quantitatively by a cell sorter as markers of macrophage differentiation. The BMM phi from MRL/l contained a much smaller number of Ia antigen-positive macrophages than those from normal mice. Treatment of BMM phi with an Ia-inducing of factor (IFN-gamma) markedly increased the expression of Ia antigens. This increase was significantly greater in BMM phi from MRL/l mice than in BMM phi from control mice. Expression of Mac-1 antigen was not different in BMM phi from the two strains. The Fc-mediated phagocytosis of IgG-coated sheep red blood cells was decreased in BMM phi from MRL/l mice compared with those from control mice. The function of nonspecific phagocytosis as measured by latex-bead incorporation was also impaired in MRL/l mice. The functional defects of MRL/l BMM phi found in these experiments are not secondary defects acquired under the influence of environmental signals during development, but are derived from the primary abnormalities which already exist in myeloid stem cells.     

Interactions of factors bound at two different sites in the 5'-upstream region of the adenovirus 12 E1A gene

A nuclear extract of Ehrlich ascites tumor cell contains factors binding to two distinct sites in the 5'-upstream region of the adenovirus 12 E1A gene. The gel shift assay was performed for characterization of the binding factors with oligo DNA probes containing sequences corresponding to these sites. The specific binding of a factor to one probe was enhanced when the other oligo DNA was present in excess in the binding reaction. Thus possibly, protein-protein interactions between factors may mutually prevent their binding to target sequences.     

Regeneration of bovine and octopus opsins in situ with natural and artificial retinals

We consider the problem of color regulation in visual pigments for both bovine rhodopsin (lambda max = 500 nm) and octopus rhodopsin (lambda max = 475 nm). Both pigments have 11-cis-retinal (lambda max = 379 nm, in ethanol) as their chromophore. These rhodopsins were bleached in their native membranes, and the opsins were regenerated with natural and artificial chromophores. Both bovine and octopus opsins were regenerated with the 9-cis- and 11-cis-retinal isomers, but the octopus opsin was additionally regenerated with the 13-cis and all-trans isomers. Titration of the octopus opsin with 11-cis-retinal gave an extinction coefficient for octopus rhodopsin of 27,000 +/- 3000 M-1 cm-1 at 475 nm. The absorption maxima of bovine artificial pigments formed by regenerating opsin with the 11-cis dihydro series of chromophores support a color regulation model for bovine rhodopsin in which the chromophore-binding site of the protein has two negative charges: one directly hydrogen bonded to the Schiff base nitrogen and another near carbon-13. Formation of octopus artificial pigments with both all-trans and 11-cis dihydro chromophores leads to a similar model for octopus rhodopsin and metarhodopsin: there are two negative charges in the chromophore-binding site, one directly hydrogen bonded to the Schiff base nitrogen and a second near carbon-13. The interaction of this second charge with the chromophore in octopus rhodopsin is weaker than in bovine, while in metarhodopsin it is as strong as in bovine.     

Amino acid content in several brain regions of the active and hibernating frog, Rana esculenta

1. Total free amino acid contents in the optic lobe and diencephalon increased significantly during hibernation. 2. Free glutamate + glutamine showed significant increases in the cerebral hemisphere, optic lobe, medulla oblongata and diencephalon. 3. Free aspartate + asparagine showed significant increases in the cerebral hemisphere, optic lobe, diencephalon and olfactory lobe. 4. GABA showed a significant change only in the medulla oblongata. 5. Total protein amino acid level in the cerebellum and olfactory lobe decreased significantly during hibernation and most of the amino acids decreased significantly in these regions. 6. The amino acid metabolism during amphibian hibernation differs from that of the mammal.     

A monoclonal antibody to the carbohydrate chain on human hepatocellular carcinoma-associated antigen which suppressed tumor growth in nude mice

Summary There have been few reports stating that monoclonal antibody alone inhibits human solid tumor growth in vivo. The present study demonstrated that monoclonal antibody S1 (IgG2a), which recognized the antigenic determinant of the carbohydrate moiety, showed antibody-dependent cell (or macrophage)-mediated cytotoxicity (ADCC or ADMC) in conjunction with murine splenocytes of both BALB/c and athymic mice. In vivo experiments demonstrated that the antibody S1 clearly prolonged the survival of athymic mice which had been inoculated with a human liver carcinoma cell line. In addition, the antibody S1 significantly suppressed the human hepatoma line transplanted s.c. into nude mice. ¹²⁵I-Labeled monoclonal antibody S1 revealed that the antibody accumulated significantly in the tumor mass. Many mononuclear cells were observed surrounding tumor cells when the antibody was given. This model system might be useful for analyzing the ADCC (or ADMC) mechanism in vivo.     

Breeding ofl-threonine hyper-producer ofEscherichia coli W

Summary l-Threonine hyper-producing mutants were obtained fromEscherichia coli W strain KY-8366, by reducingl-threonine degradation activity and enhancingl-threonine biosynthetic activity. Anl-threonine degradation reaction test using resting cells of KY-8366 suggested that the main pathway ofl-threonine degradation by KY-8366 is via glycine. A strain with reducedl-threonine degradation activity was obtained among those mutants that could not utilizel-threonine as sole nitrogen source. Rifampicin-resistant mutants andl-lysine plus methionine-insentitive mutants were isolated. These mutants showed enhanced aspartokinase levels and accumulated morel-threonine than the parental strains. Mutant H-4290 accumulated 58 g/l ofl-threonine.     

l-threonine production by l-aspartate- and l-homoserine-resistant mutant of Escherichia coli

Summary Growth and l-threonine productivity of l-threonine producer Escherichia coli H-4290 were inhibited by precursor amino acids, l-homoserine and l-aspartate. l-Threonine hyper-producers were isolated among the mutants resistant to l-homoserine and l-aspartate. Mutants H-4351 (Hom^r) and H-4578 (Hom^r, Asp^r) accumulated 22.2 g/l and 24.3 g/l of l-threonine in test tube cultures, while the parental strain H-4290 accumulated 18.2 g/l. The enzyme level of aspartokinase I (first enzyme of the threonine operon) was enhanced 2.3 times (H-4351) and 3 times (H-4578) that of H-4290. Mutant H-4578 accumulated 76 g/l of l-threonine in a 2-l jar fermentor after 75 h cultivation.Abbreviations DAP diaminopimeric acid - Met ^l poor growth in methionine-free medium - AHV -amino--hydroxyvaleric acid - Thr-N^- lack of ability to utilize l-threonine as a nitrogen source - Rif rifampicin - Lys+Met^r resistant to l-lysine and dl-methionine