Stimulation of proliferation ofTetrahymena pyriformis by trace rare earths

Using two Chinese strains ofTetrahymena pyriformis, S1 and BJ4, as the biological models, the effects of lighter rare earths (lanthanum, cerium, praseodymium, neodymium, samarium, and europium), representatives of heavier rare earths (yttrium and thulium), and mixed rare earths were studied. The stimulation of population growth ofTetrahymena in peptone-glucose media containing trace amounts of these elements have been observed. The mechanisms for the beneficial effects of rare earth elements in low concentrations remains to be discovered.     

Serological survey of T-lymphocyte differentiation antigens in wild mice

Allelic distributions of Thy-1, Ly-l, and Ly-2 antigens in wild mice are characteristic of each Mus musculus subspecies. Eastern mice (M.m.molossinus, M.mmusculus, M.m.castaneus, M.m.bactrianus) express the Thy-1.1 antigen, whereas Western mice (M.m. domesticus, M.m.brevirostris) express the Thy-1.2. All mice from wild populations examined in this survey express the Ly-1.2. The Ly-2.1 is distributed in Eastern mice and some Western mice, and the Ly-2.2 is found in the remaining Western mice. Allelic distributions of these antigens were also examined in two other species, Mus spretus and Mus spicilegus. Allelic constitutions of Thy-1 and Ly-1 in these species are similar to those of Eastern mice. Some M.spicilegus, however, express the Ly-1.1 antigen. This antigenic type is not found in M.musculus. Some Eastern mice related to M.m.castaneus react weakly to Ly-1.2-specific and Ly-2.1-specific monoclonal antibodies in both the complement-mediated cytotoxicity test and the absorption test. These results suggest that M.m.castaneus has unique alleles in the Ly-1 and Ly-2 loci.     

Anther culture of papaya (Carica papaya L.)

Papaya (Carica papaya L.) anther containing microspores in tetrad to early-binucleate stages were successfully cultured on 1/2 strength MS salts and vitamins with full strength Na-Fe-EDTA supplemented with 2 mg/l NAA, 1 mg/l BA and 6% sucrose for callus initiation and formation. Highest frequencies of callus induction were obtained when anthers at the uninucleate stage were cultured in the dark. Haploid plantlets and pollen-derived embryoids were obtained from anthers cultured at the uninucleate stage on solidified MS medium containing 3% sucrose without any growth regulators under a low light intensity (1,500 lux). Large quantities of embryoids were obtained when the original embryoids were transferred to MS medium with 3% sucrose and no growth regulators. Cytology of root tips of embryoid-derived plants confirmed the haploid chromosome number of 9 indicating that the embryoids originated from pollen.Abbreviations MS Murashige and Skoog (1962) - MAA naphthaleneacetic acid - BA 6-benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid     

Influence of cholesterol content on red cell membrane viscoelasticity and fluidity.

The purpose of this investigation was to correlate the viscoelastic properties and lipid fluidity of the red blood cell membrane to its lipid composition. The viscoelastic properties of human red cells that had been enriched or depleted in cholesterol were determined by the micropipette technique. The lipid fluidity of the outer and inner leaflets of the erythrocyte membrane was concurrently assessed by steady state fluorescence depolarization. The elastic modulus and the viscosity moduli of the erythrocyte membrane showed no significant differences between the cholesterol-modified and the control cells. Cholesterol enrichment decreased the lipid fluidity of the outer membrane leaflet alone, and cholesterol depletion increased the fluidity mainly of the inner leaflet.     

Conversion of a primary amine to a labeled secondary amine by the addition of phenolic group and radioiodination

To preserve the nucleophilicity of amino compounds during conjugative radioiodination, a new method for converting primary amines to phenolic secondary amines was developed. Amino acids were used as model compounds for establishing optimal conditions for the reductive amination. In the first step of the reaction, the aldehyde group of 4-hydroxybenzaldehyde (formylphenol) was reacted reversibly with an amino group to form an imine. The irreversible attachment of formylphenol to the amino group was accomplished by reduction of the imine with sodium cyanoborohydride. The pH optimum for the reaction was 5.0. Higher temperature has favorable effects on the rate and extent of the conjugation. Phenolic derivatives of amino compounds suitable for radioiodination are produced by the reactions described.     

Yeast mannans inhibit binding and phagocytosis of zymosan by mouse peritoneal macrophages

We have examined the effects of various mannans, glycoproteins, oligosaccharides, monosaccharides, and sugar phosphates on the binding and phagocytosis of yeast cell walls (zymosan) by mouse peritoneal macrophages. A phosphonomannan (PO(4):mannose ratio = 1:8:6) from kloeckera brevis was the most potent inhibitor tested; it inhibited binding and phagocytosis by 50 percent at concentrations of approximately 3-5 μg/ml and 10 μg/ml, respectively. Removal of the phosphate from this mannan by mild acid and alkaline phosphatase treatment did not appreciably reduce its capacity to inhibit zymosan phagocytosis. The mannan from saccharomyces cerevisiae mutant LB301 inhibits phagocytosis by 50 percent at 0.3 mg/ml, and a neutral exocellular glucomannan from pichia pinus inhibited phagocytosis by 50 percent at 1 mg/ml. Cell wall mannans from wild type S. cervisiae X2180, its mnn2 mutant which contains mannan with predominantly 1(arrow)6- linked mannose residues, yeast exocellular mannans and O-phosphonomannans were less efficient inhibitors requiring concentrations of 1-5 mg/ml to achieve 50 percent reduction in phagocytosis. Horseradish peroxidase, which contains high-mannose type oligosaccharides, was also inhibitory. Mannan is a specific inhibitor of zymosan binding and phagocytosis. The binding and ingestion of zymosan but not of IgG- or complement-coated erythrocytes can be obliterated by plating macrophages on substrates coated with poly-L-lysin (PLL)-mannan. Zymosan uptake was completely abolished by trypsin treatment of the macrophages and reduced by 50-60 percent in the presence of 10 mM EGTA. Pretreatment of the macrophages with chloroquine inhibited zymosan binding and ingestion. These results support the proposal that the macrophage mannose/N-acetylglucosamine receptor (P. Stahl, J.S. Rodman, M.J. Miller, and P.H. Schlesinger, 1978, Proc. Natl. Acad. Sci. U.S.A. 75:1399-1403, mediates the phagocytosis of zymosan particles.     

A monoclonal antibody from infected mice to a Schistosoma mansoni egg proteinase

A number of monoclonal antibodies were obtained by fusion of SP2/0 myeloma cells and spleen lymphocytes from mice infected with Schistosoma mansoni. These antibodies were tested for their ability to inhibit acidic, thiol-dependent proteinases previously isolated from Schistosoma mansoni eggs and adult worms. One of the monoclonal antibodies isolated inhibits egg proteinase activity measured in vitro with the use of a low m.w. synthetic substrate. This antibody, which is an IgG1 isotype, does not appreciably inhibit an acidic, thiol-dependent proteinase obtained from the adult stage of Schistosoma mansoni. Immunocytochemical methods with the monoclonal antibody have been used to localize the egg proteinase within a set of "penetration" glands in the unhatched miracidium.     

Genetic characterization of mouse immunoglobulin allotypic determinants (allotopes) defined by monoclonal antibodies

We have generated a new series of monoclonal antibodies recognizing allotypic determinants on mouse IgG₁, IgG_2a, and IgG_2b. In this communication we describe their reactivities with immunoglobulins of the inbred mouse strains. Comparison with serology charts indicates that many of these monoclonal antibodies detect allotypic specificities previously defined by conventional antisera; others define previously undescribed specificities. Strain and isotype distribution allows us to assign five new allotypic specificities to Igh-1 and three new specificities to Igh-3. In addition, on the basis of reactivity with the monoclonal antibodies, we have defined a new Igh haplotype in SWR/J mice, Igh ^p.Abbreviations used in this paper Igh immunoglobulin heavy chain - SDS sodium dodecyl sulfate     

The isolation and properties of phenylalanine hydroxylase from human liver

Phenylalanine hydroxylase was prepared from human foetal liver and purified 800-fold; it appeared to be essentially pure. The phenylalanine hydroxylase activity of the liver was confined to a single protein of mol.wt. approx. 108000, but omission of a preliminary filtration step resulted in partial conversion into a second enzymically active protein of mol.wt. approx. 250000. Human adult and full-term infant liver also contained a single phenylalanine hydroxylase with molecular weights and kinetic parameters the same as those of the foetal enzyme; foetal, newborn and adult phenylalanine hydroxylase are probably identical. The K(m) values for phenylalanine and cofactor were respectively one-quarter and twice those found for rat liver phenylalanine hydroxylase. As with the rat enzyme, human phenylalanine hydroxylase acted also on p-fluorophenylalanine, which was inhibitory at high concentrations, and p-chlorophenylalanine acted as an inhibitor competing with phenylalanine. Iron-chelating and copper-chelating agents inhibited human phenylalanine hydroxylase. Thiol-binding reagents inhibited the enzyme but, as with the rat enzyme, phenylalanine both stabilized the human enzyme and offered some protection against these inhibitors. It is hoped that isolation of the normal enzyme will further the study of phenylketonuria.