Characterization of Thy-1 with monoclonal antibodies and evidence of Thy-3.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
M Barad
Publications and source records attributed to M Barad.
Human beta 2-microglobulin specifically enhances cell-surface expression of HLA class I molecules in transfected murine cells.
Sequential transfections of P815 murine mastocytoma cells with class I gene encoding either HLA-Cw3, HLA-A3, or HLA-B7 H chain and subsequently with a human beta 2-microglobulin gene were performed to evaluate the relative efficiency of human and murine beta 2-microglobulins in promoting the cell-surface expression of HLA-class I molecules. A 6-, 11-, and 40-fold specific enhancement of the cell-surface expression of HLA-Cw3, HLA-A3, and HLA-B7 molecules, respectively, was observed in cells co-transfected with human beta 2-microglobulin gene. This effect was attributed to a more efficient association of HLA H chains with human than with murine beta 2-microglobulin, which apparently allowed a more rapid transport of the HLA molecules from the endoplasmic reticulum to the Golgi apparatus.
Animals↗
A novel, tissue-specific, Drosophila homeobox gene.
The homeobox gene family of Drosophila appears to control a variety of position-specific patterning decisions during embryonic and imaginal development. Most of these patterning decisions determine groups of cells on the anterior-posterior axis of the Drosophila germ band. We have isolated a novel homeobox gene from Drosophila, designated H2.0. H2.0 has the most diverged homeobox so far characterized in metazoa, and, in contrast to all previously isolated homeobox genes, H2.0 exhibits a tissue-specific pattern of expression. The cells that accumulate transcripts for this novel gene correspond to the visceral musculature and its anlagen.
Amino Acid Sequence↗
Metabolic flux of cyclic GMP and phototransduction in rabbit retina.
1. Rabbit retinas were isolated and subjected in vitro to shifts between light and darkness in the presence or absence of four concentrations of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Changes in the rate of cyclic GMP hydrolysis (determined by 18O labelling of guanine nucleotide alpha-phosphoryls) and in total cyclic GMP content (determined by radioimmunoassay) were compared with the changes in the electrical potential across the retina. The experiments were designed so that the changes in potential would reflect changes in the light-sensitive conductance of the photoreceptors. 2. IBMX at 27-730 microM caused dose-related reductions in cyclic GMP hydrolysis in both light and darkness. The reductions in hydrolysis were associated with almost equal reductions in synthesis, so that there was little increase in the total content of cyclic GMP despite large changes in its metabolic flux. 3. Shifting from light (2.3 x 10(3) photons microns-2 s-1) to darkness also caused large reductions in the metabolic flux of cyclic GMP, with little increase in its total content. 4. Reductions in cyclic GMP flux were always associated with increases in the vitreous-positive transretinal potential, which was used as a measure of photoreceptor outer segment conductance, and the inverse correlation between flux and potential was closely maintained (r = 0.98) under all conditions examined. The correlation between total cyclic GMP content and transretinal potential was much less close. 5. Since IBMX and darkness acted similarly and additively, the combination of IBMX and darkness caused large decreases, of up to 21-fold, in cyclic GMP flux and large increases, of up to 23-fold, in the transretinal potential. 6. Kinetic analysis of the data indicated that the great majority (about 95%) of the light-sensitive conductance was closed under physiological conditions in darkness. 7. The data appear to be consistent with a system in which much of the cyclic GMP is bound, in which the binding is increased by light, and in which the free cyclic GMP acts co-operatively with a Hill coefficient of 3 to open outer segment conductance and to inhibit guanylate cyclase.
1-Methyl-3-isobutylxanthine↗
Evidence that murine hematopoietic cell subset marker J11d is attached to a glycosyl-phosphatidylinositol membrane anchor.
Glycosyl-phosphatidylinositol (G-PI) has been shown to serve as membrane anchor for cell surface molecules such as Thy-1, Ly-6-controlled ThB and Qa antigens. Here, we present several lines of evidence indicating that the hematopoietic cell lineage (i.e. thymocytes, B cell subset and red blood cells) marker defined by the rat monoclonal antibody J11d is also a G-PI-linked structure. First, surface expression of the J11d-defined molecules, and that of the related antigen B2A2, was found to be specifically reduced by treatment of thymocytes and B lymphoma or hybridoma cells with excess of Staphylococcus aureus PI-specific phospholipase C; this enzyme also solubilizes a 35-40-kDa material from erythrocyte microsomal membranes corresponding to the predominant J11d-reactive red cell surface molecules. Second, Thy-1- mutants of the BW5147, T1M1, S1A or S49 murine T lymphoma cells of the complementary classes A, B, C and E (i.e. shown to be defective in the enzymatic machinery that posttranslationally modify Thy-1 molecules) also lack J11d, or express it at a very low level. Although directed at a G-PI-linked structure, the J11d monoclonal antibody, unlike other reagents to Thy-1 or Ly-6-controlled antigens, failed to induce thymocyte proliferation even in the presence of phorbol myristate acetate and cross-linker monoclonal antibody.
Animals↗
Phenotypic evolution of CTL B-lines in vitro.
This study demonstrates that cytolytic T-cell lines exhibit progressive in-vitro modifications of their phenotype and of their growth behaviour and may use different pathways for their multiplication. Comparing three established cell lines, we firstly demonstrated that the expression of LFA-I is stable but the Lyt 2, 3 is rapidly lost. In this case, a high lectin-dependent cytotoxicity appears. Secondly, we demonstrated that two of the cell lines used the interleukin 2-interleukin 2 receptors (IL-2-IL-2R) binding pathway. Two different monoclonal antibodies showed that the IL-2 receptors distribution does not correlate with the number of functional sites which determines the IL-2 requirement. In contrast, the third cell line, although bearing high levels of IL-2 receptors, grows without the addition of IL-2; this cell growth is not inhibited by anti-IL-2 receptors monoclonal antibodies. Thirdly, it appears that the new property of IL-2 independence is associated with acquisition of the simultaneous capacity to induce tumour grafts in nude mice. As it has been recently reported that cytolytic T-lymphocytes against tumour cells could be promising immunotherapeutic agents, the spontaneous malignant transformation of such CTL lines should be taken into account before using them for adoptive immunotherapeutic purposes.
Animals↗
Light-induced increases in cGMP metabolic flux correspond with electrical responses of photoreceptors.
The metabolism of photoreceptor cGMP and the relationship of its light-sensitive regulation to rhodopsin photoisomerization and to the photoreceptor electrical response was examined in isolated, intact rabbit retinas. The dynamics of cGMP metabolism were assessed by measuring the rate of 18O incorporation from 18O-water into the alpha-phosphoryls of the guanine nucleotides. The photoreceptor electrical response was determined by measuring the aspartate-isolated mass receptor potential. Basal cGMP flux in dark-adapted retinas was 33 pmol cGMP X mg protein-1 X s-1 which translates into a metabolic rate in the rod outer segment (ROS) of 1.7 mM/min in ATP equivalents. Photic stimulation increased this flux as much as 4.5-fold. With continuous illumination, increasing intensity caused increments in cGMP metabolic flux to a maximum of 4.5-fold, with corresponding increases in the electrical response over the same 3-log unit intensity range. Tight coupling between activation of guanylate cyclase and phosphodiesterase was indicated by either no changes in cGMP steady state concentrations or relatively small fluctuations represented by increases of 50% at lower light intensities and a 12% decrease at one of the highest intensities. A stoichiometry of about 10,000 molecules of cGMP generated and hydrolyzed per photon absorbed was calculated for the lowest light intensity when the increment in cGMP metabolic flux per photon was maximal. Flashing light caused an increase in flux in proportion to frequency up to 1 Hz and a nearly proportional increase in the voltage time integral of the electrical response up to 0.5 Hz. This indicates that the temporal resolution, or "on"/"off" rate, of the cGMP metabolic response was as fast or faster than the temporal resolution of the electrical response. The concentration of cGMP remained relatively stable in spite of the marked acceleration of cGMP flux that occurred over the 32-fold range of frequencies tested. Taken together these results show that the light-accelerated rate of cGMP synthesis tightly coupled to hydrolysis becomes a primary energy-utilizing system in the photoreceptor and represents a response that fulfills certain of the fundamental criteria required of a metabolic event playing an essential role in phototransduction.
Animals↗