Cell surface immunoglobulin XXI. appearance of IgD on murine lymphocytes during differentiation.

The differentiation of Ig-bearing lymphocytes in adult mice was studied by monitoring the appearance of IgD relative to IgM on the surface of splenocytes obtained from lethally irradiated animals reconstituted for various periods of time with adult bone marrow cells, neonatal splenocytes, or Ig- adult splenocytes. It was found that IgM appears before IgD on differentiating lymphocytes. Furthermore, the rate of appearance of IgD during differentiation of adult cells is similar to that observed with neonatal cells.     

Tannic acid effect on membrane of cell surface origin in guinea pig megakaryocytes and platelets.

Plasma membranes in isolated guinea pig megakaryocytes and washed platelets are poorly stained with the usual methods used to outline cell membranes. The addition of tannic acid and calcium to the initial fixative is useful to enhance electron density of all surface-derived membrane systems in these cells. The method described here shows that the increased electron denisty of membrane after fixation in the presence of tannic acid occurs both at the cell surface and along the invaginated membrane systems.     

Cross-reactivity of rat, mouse, and human IgD.

Highly purified sheep anti-rat lymphocyte membrane IgD (mIgD) was used to detect cross-reactivity with the putative murine-delta chain on mouse lymphocytes. Cross-reactivity is demonstrated by indirect immunofluorescent staining and by immunoprecipitation of 125I-labeled lymphocyte membrane extracts followed by electrophoresis on 10% polyacrylamide gels. In addition, cross-reactivity of anti-rat-delta with human IgD is shown by gel diffusion analysis. The anti-rat-delta reagent stained both Ig5a+ and Ig5b+ lymphocytes. Preincubation of Ig5b+ (but not Ig5a+) cells with monoclonal allotype-specific antibodies (anti-Ig5b) under capping conditions caused inhibition of staining by the sheep anti-rat-delta reagent, indicating that it is the delta-chain that is recognized on mouse lymphocytes and that the anti-rat-delta reagents does not distinguish between mouse-delta allotypes. Furthermore, absorption of the sheep anti-rat-delta serum with purified human IgD reduced subsequent staining of mouse lymphocytes by approximately 50%; staining was not affected by absorption with human IgM. This xenogeneic anti-delta antiserum appears to detect determinants on the delta-heavy chain, which are shared by at least three species of mammals, suggesting that these determinants represent important molecular features conserved during evolution.     

The effect of uremic serum on normal human and guinea pig lymphocytes.

Incubation of normal 51-Cr-labeled human and guinea pig lymphocytes with uremic serum or guanidinosuccinic acid did not cause an increase in 51-Cr release. Electron microscopic examination of these lymphocytes revealed no abnormalities. It is suggested that the lymphocytopenia of uremia is not due to increased destruction of cells but may be a result of redistribution to other body compartments.     

Comparison of brain ribonucleases of rabbit, guinea pig, rat, mouse and gerbil

The brain ribonucleases of rabbit, guinea pig, rat, mouse and gerbil were investigated by histochemical and biochemical methods. For the localization, the ribonucleases were electrophoretically transferred from cryostat sections to polyacrylamide gels. Elevated ribonuclease activities were found in the cortex, the basal ganglia, the hippocampal formation and the ventricles, whereas the corpus callosum and the internal capsule exhibited lower activities. The total RNA degrading activities of the brain extracts of the different species varied in a wide range. However, a pre-requisite for the measurement of acid soluble degradation products in the test system was the inactivation of endogeneous ribonuclease inhibitors, present in all extracts. Molecular weight analysis by means of SDS-polyacrylamide gel electrophoresis revealed a characteristic set of ribonucleases for each species, consisting of enzymes with different pH-optima.     

Comparison of brain ribonucleases of rabbit,guinea pig,rat, mouse and gerbil

Summary The brain ribonucleases of rabbit, guinea pig, rat, mouse and gerbil were investigated by histochemical and biochemical methods. For the localization, the ribonucleases were electrophoretically transferred from cryostat sections to polyacrylamide gels. Elevated ribonuclease activities were found in the cortex, the basal ganglia, the hippocampal formation and the ventricles, whereas the corpus callosum and the internal capsule exhibited lower activities. The total RNA degrading activities of the brain extracts of the different species varied in a wide range. However, a pre-requisite for the measurement of acid soluble degradation products in the test system was the inactivation of endogencous ribonuclease inhibitors, present in all extracts. Molecular weight analysis by means of SDS-polyacrylamide gel electrophoresis revealed a characteristic set of ribonucleases for each species, consisting of enzymes with different pH-optima.Dedicated to Professor Dr. T.H. Schiebler on the occasion of his 65th birthday     

Effects of progesterone on the oestrogen-stimulated uterus: a comparative study of the mouse, guinea pig, rabbit and sheep.

To examine more closely the anti-oestrogenic action of progesterone (P), its effect on various parameters in the 17 beta-oestradiol (E2)-primed uterus of the mouse, guinea pig, rabbit and ewe was studied. Changes in uterine wet weight, rate of in vitro protein synthesis, protein : DNA and RNA : DNA ratios, peroxidase activity and the level of cytosol receptors for E2 and P were measured. Considerable between-species differences in the effect of P on these parameters were observed. The anti-uterotrophic action was greater in the mouse than in the guinea pig and was not seen in the rabbit or ewe. P inhibited protein synthesis in the mouse, was without significant effect in the guinea pig and was mildly stimulatory in the rabbit and ewe. Inhibitory effects on protein : DNA and RNA : DNA ratios were substantial in the mouse, minor in the guinea pig and absent in the rabbit and ewe. Peroxidase activity was decrease in the mouse and guinea pig, essentially lacking in the rabbit and not detectable in the ewe. In all species the level of both oestrogen and progesterone cytosol receptors was decreased, although the effect on the E2 receptor was less marked in the ewe. The results indicate that in the species studied an effect of P on the replenishment of the E2 receptor is not necessarily associated with other anti-oestrogenic actions of P and argue against the concept that initial anti-oestrogenic actions of P are mediated via a specific effect on such replenishment.     

Difference in cell surface 5'-nucleotidase activity, protein iodination and membrane properties between mouse lymphoma and rat adenocarcinoma cell variants with low and high-metastatic potential

1. Distinct differences were found for the specific, concanavalin A-inhibitable 5'-nucleotidase activity, exhibiting 2-7 times higher values in the low-metastasizing cell variants. 2. Iodination of the cell surface proteins revealed a more heterogeneous labelling pattern of the high-malignant cell lines in the molecular weight range between 14 and about 35 kDa. 3. The low-malignant cell lines exhibited a significantly higher surface charge as deduced from their higher sialic acid content compared to the high-malignant variants. 4. They also showed a greater membrane lipid fluidity as determined both by the cholesterol to phospholipid ratio and by fluorescence depolarization measurements.     

Action of interferon on cell membrane of mouse lymphocytes : Inhibition of ligand-induced redistribution of surface receptors

Mouse interferon at 50–100 U/ml or higher concentrations inhibited cap formation of surface components on mouse lymphocytes induced by anti-lymphocyte serum, concanavalin A (ConA), phytohemagglutinin (PHA) and soybean agglutinin (SBA). Interferon from species other than mouse were not effective, suggesting that interferon itself in the preparations used was responsible for the observed effect. The inhibition was observed immediately after addition of interferon, without preincubation of cells with it. The effect was reversible, disappearing after a short lag when interferon was removed. The effect may thus be a reflection of a rapid change in cell membrane upon binding of interferon molecules. On the other hand, the cap formation by anti-immunoglobulin, anti-thy 1, 2, anti-H-2 sera and wheat germ agglutinin (WGA) were not influenced by interferon at all, indicating that the inhibition by interferon was not a general phenomenon. The cap formations susceptible to interferon are those that are enhanced by pretreatment of cells with colchicine and are accompanied by marked uropod formation, but those insusceptible to interferon occur readily, becoming sharp spots which are then shed. It is suggested that interferon may modify the microtubule-containing structure, it it may selectively affect those membrane components that are anchored to it.