Decreased expression of J11d antigen during monocytic differentiation of M1 myeloid leukemic cells.

Four myeloid cell lines (M1, WEHI-3B D+, FDC-P1, and 32D) were screened for the presence of J11d antigen. One of these cell lines, the myeloid leukemia M1, was found to express a high level of J11d antigen on the cell surface. Recombinant mouse leukemic inhibitory factor (rm-LIF), recombinant human LIF (rh-LIF), and steroids (hydrocortisone and dexamethasone) could induce M1 cells to undergo monocytic differentiation. The level of J11d antigen was greatly reduced after treatment of the cells with LIF or steroids. Western blotting revealed that the apparent molecular weight of the J11d antigen on M1 cells was 45-48 kDa. Furthermore, the level of J11d mRNA was also reduced during LIF-induced differentiation of M1 cells.     

Sensitization of mice with wild-type and cold-adapted influenza virus variants: immune response to two H1N1 and H3N2 viruses

Two A strain influenza viruses, A/Hong Kong/123/77 (A/HK/123/77) (H1N1) and A/Queensland/6/72 (A/Qld/6/72) (H3N2), and the two cold-adapted reassortants which possess the surface antigens of these strains (CR35 and CR6, respectively) were tested for their ability both to induce primary cytotoxic T-cell (Tc cell) responses in mice and to sensitize mice for a second Tc cell response when challenged with a distantly related A strain virus, A/Shearwater/72 (H6N5). After intranasal inoculation, A/Qld/6/72 replicated to higher titers in the lung (1 to 2 log10 50% egg infective doses) than did A/HK/123/77 or either of the reassortants. A/Qld/6/72 induced higher Tc cell responses in the lung than did CR6, and both were more effective than either A/HK/123/77 or CR35 in this respect. When similar doses (10 or 10(3) hemagglutinin units) of each virus were injected intravenously into mice and the spleens were tested for Tc cell activity 6 days later, both A/Qld/6/72 and CR6 were ca. 100-fold better at inducing a primary Tc cell response than A/HK/123/77 or CR35. In contrast, the H1N1 and H3N2 viruses gave rather similar anti-hemagglutinin antibody titers (after intravenous injection) and delayed-type hypersensitivity reactions (after subcutaneous injection). If mice were primed with a low dose of these viruses (10(4) 50% egg infective doses intranasally), A/Qld/6/72 and CR6 were more effective than A/HK/123/77 or CR35 at sensitizing for a secondary Tc cell response when challenged with A/Shearwater/72, but if larger doses were given either intranasally (10(6) 50% egg infective doses) or intravenously (10 to 10(3) hemagglutinin units), all viruses sensitized the mice equally well, despite the fact the A/Shearwater/72 gives a poor primary Tc cell response in mice. Thus, the viral glycoprotein antigens can be important in determining the immunogenicity of the virus and, particularly, the class I antigen-restricted Tc cell response of the host.     

Apical Scaffolding Protein NHERF2 Modulates the Localization of Alternatively Spliced Plasma Membrane Ca2+ Pump 2B Variants in Polarized Epithelial Cells

The membrane localization of the plasma membrane Ca²⁺-ATPase isoform 2 (PMCA2) in polarized cells is determined by alternative splicing; the PMCA2w/b splice variant shows apical localization, whereas the PMCA2z/b and PMCA2x/b variants are mostly basolateral. We previously reported that PMCA2b interacts with the PDZ protein Na⁺/H⁺ exchanger regulatory factor 2 (NHERF2), but the role of this interaction for the specific membrane localization of PMCA2 is not known. Here we show that co-expression of NHERF2 greatly enhanced the apical localization of GFP-tagged PMCA2w/b in polarized Madin-Darby canine kidney cells. GFP-PMCA2z/b was also redirected to the apical membrane by NHERF2, whereas GFP-PMCA2x/b remained exclusively basolateral. In the presence of NHERF2, GFP-PMCA2w/b co-localized with the actin-binding protein ezrin even after disruption of the actin cytoskeleton by cytochalasin D or latrunculin B. Surface biotinylation and fluorescence recovery after photobleaching experiments demonstrated that NHERF2-mediated anchorage to the actin cytoskeleton reduced internalization and lateral mobility of the pump. Our results show that the specific interaction with NHERF2 enhances the apical concentration of PMCA2w/b by anchoring the pump to the apical membrane cytoskeleton. The data also suggest that the x/b splice form of PMCA2 contains a dominant lateral targeting signal, whereas the targeting and localization of the z/b form are more flexible and not fully determined by intrinsic sequence features.     

The chemical-transformation products of 1,6-dibromo-1,6-dideoxygalactitol and 1,2:5,6-dianhydrogalactitol in aqueous solution

After hydrolysis of 1,6-dibromo-1,6-dideoxygalactitol (1) and 1,2:5,6-dianhydrogalactitol (2), 11 compounds were isolated, three of them as tritylated derivatives. Their structures were established on the basis of chemical evidence and, for four compounds, by X-ray diffraction. The main product of the hydrolysis of 1 was 3,6-anhydro-1-bromo-1-deoxy-dl-galactitol; the end-products of the hydrolysis of 2 were 1,5-anhydro-dl-galactitol, 2,5-anhydro-dl-altritol, and galactitol.     

Somatic cell fusion of Trichoderma reesei resulting in new genetic combinations

Summary A selection method has been developed for the isolation of recombinant strains of Trichoderma reesei QM 9414. The method is based on somatic hybridization via anastomosis or protoplast fusion, and on the difference in growth rate of the resulting heterokaryons and synkaryons. The more intensive growth of the synkaryons as due to allelic complementation of adenine-requiring auxotrophic strains mutated in the adenylosuccinate synthetase gene. The synkaryons appeared is energetically growing spots in the heterokaryotic background. Stable diploids could not be isolated, which points to the transient nature of the diploid state in this species.     

Alga consumption of four dominant planktonic crustaceans in Lake Balaton (Hungary)

Between 1981–83 the gut contents ofDaphnia galeata, D. cucullata, Eudiaptomus gracilis, andCyclops vicinus were examined with light and scanning electron microscope to obtain information on the feeding of these species in Lake Balaton. The twoDaphnia species feed mainly on abioseston, and it is assumed that their primary nutrient source was organic matter adsorbed onto the surfaces of the abioseston granules plus bacteria and detritus.E. gracilis feeds on algae, showing a preference for green algae and diatoms.C. vicinus is also a prodigious consumer of algae in Lake Balaton, utilizing the whole size spectrum of phytoplankton. Concerning the trophic relationships between phytoplankton and zooplankton in Lake Balaton, that between diatoms and bothE. gracilis andC. vicinus is the most conspicouos. Convincing evidence for an extensive utilization of blue-green algae was not found. Though there is no firm evidence yet, it is likely that theDaphnia are dependent on organic matter adsorbed on the abioseston.     

A differential scanning calorimetric study of the thermotropic phase behavior of model membranes composed of phosphatidylcholines containing linear saturated fatty acyl chains

The thermotropic phase behavior of a series of 1,2-diacylphosphatidylcholines containing linear saturated acyl chains of 10-22 carbons was studied by differential scanning calorimetry. When fully hydrated and thoroughly equilibrated by prolonged incubation at appropriate low temperatures, all of the compounds studied form an apparently stable subgel phase (the Lc phase). The formation of the stable Lc phase is a complex process which apparently proceeds via a number of metastable intermediates after being nucleated by incubation at appropriate low temperatures. The process of Lc phase formation is subject to considerable hysteresis, and our observations indicate that the kinetic limitations become more severe as the length of the acyl chain increases. The kinetics of Lc phase formation also depend upon whether the acyl chains contain an odd or an even number of carbon atoms. The Lc phase is unstable at higher temperatures and upon heating converts to the so-called liquid-crystalline state (the L alpha phase). The conversion from the stable Lc to the L alpha phase can be a direct, albeit a multistage process, as observed with very short chain phosphatidylcholines, or one or more stable gel states may exist between the Lc and L alpha states. For the longer chain compounds, conversions from one stable gel phase to another become separated on the temperature scale, so that discrete subtransition, pretransition, and gel/liquid-crystalline phase transition events are observed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunogold localization of photosynthetic fructose-1,6-bisphosphatase in pea leaf tissue

An enriched IgG serum fraction obtained from rabbits immunized against pea chloroplast fructose-1,6-bisphosphatase (FBPase) was used, coupled to colloidal gold (15 nanometer particles) goat anti-rabbit IgG, to analyze by electron microscopy the location of photosynthetic FBPase in pea (Pisum sativum L.) leaf ultrathin sections. In accordance with earlier biochemical studies on distribution of FBPase activity, the enzyme was visualized both in the stromal space and bound to the chloroplast membranes. Some gold particles also appear in the cytoplasm, which can be related to the presence in the cytosol of a high molecular weight precursor of this nuclear coded enzyme.     

T cell tolerance to Mlsa encoded antigens in T cell receptor V beta 8.1 chain transgenic mice.

To study T cell tolerance, transgenic mice were generated that expressed the Mlsa-reactive T cell receptor (TCR) beta chain V beta 8.1 (cDNA) under the control of the H-2Kb promoter/immunoglobulin heavy chain enhancer on approximately 90% of peripheral T cells. In transgenic mice bearing Mlsa, thymocytes expressing the TCR at a high density were deleted and the percentage of Thy 1.2+ lymph node cells was reduced. The CD4/CD8 ratio of mature T cells was reversed in Mlsa and Mlsb transgenic mice independent of the H-2. RNA analysis and immunofluorescence with TCR V beta-specific antibodies revealed that expression of endogenous TCR beta genes was suppressed. Both Mlsa and Mlsb TCR beta chain transgenic mice mounted a T-cell-dependent IgG response against viral antigens, whereas the capacity to generate alloreactive and virus-specific cytotoxic T cells was impaired in TCR beta chain transgenic Mlsa, but not in transgenic Mlsb mice.