Acid dissociation constants and pH values for standard "bes" and "tricine" buffer solutions in 30, 40, and 50 mass% dimethyl sulfoxide/water between 25 and -25 degrees C

Information is given concerning two standard buffer solutions suitable as pH references in 30, 40, and 50 mass% dimethyl sulfoxide (DMSO)/H2O mixed solvents at subzero temperatures from -20 to 0 degrees C, with the intention of establishing a pH (designated pH*) scale. The two buffers selected were the ampholytes N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid ("bes") and N-tris(hydroxymethyl)methylglycine ("tricine"), and the reference standard consisted of equal molal quantities of the buffer and its respective sodium salt. The assignment of pH* values was based on measurements of the emf of cells without liquid junction of the type: Pt;H2(g,l atm) /Bes, Na Besate, NaCl / AgCl;Ag and Pt;H2(g,l atm) /Tricine, Na Tricinate, NaCl /AgCl;Ag and the pH* was derived from a determination of K2, the equilibrium constant for the dissociation process (Buffer)+/- in equilibrium with(Buffer)- + H+.     

Purification and characterization of frog alpha-macroglobulin: receptor recognition of an amphibian glycoprotein

Frog alpha-macroglobulin was purified to apparent homogeneity by Ni2+ chelate affinity chromatography. Frog alpha-macroglobulin migrated as an alpha 1-globulin in cellulose acetate electrophoresis. A molecular weight of 730 000 was obtained by equilibrium sedimentation, and in sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE), the protein migrated as a single band of Mr approximately 360 000 before reduction and Mr approximately 180 000 after reduction. Treatment with trypsin resulted in subunit cleavage to yield a fragment of Mr approximately 90 000. After being heated, the protein fragmented, migrating in SDS-PAGE as two bands of Mr approximately 120 000 and 60 000. This fragmentation was inhibited by prior reaction of the protein with methylamine. In native pore-limit electrophoresis the protein exhibited the characteristic "slow" to "fast" conformational change of protease-treated alpha-macroglobulins. In contrast, typical "slow" to "fast" conformational change was not observed in native PAGE with this preparation. Moreover, the protein incorporated approximately 2 mol of [14C]methylamine/mol of inhibitor without demonstrating a change in mobility in native PAGE. In circular dichroism studies, the protein exhibited a spectrum similar to that of human alpha 2M. Reaction with trypsin resulted in a broadening and decrease in the magnitude of the spectrum. Reaction with methylamine resulted in similar changes, but of smaller magnitude. The inhibitor bound approximately 0.7 mol of trypsin in both radiolabeled protease binding and amidolytic titration studies. 125I-Labeled native frog alpha 1M was removed slowly from the circulation of mice with a t1/2 greater than 2h.(ABSTRACT TRUNCATED AT 250 WORDS)     

The stimulation and binding of CTP: phosphorylcholine cytidylyltransferase by phosphatidylcholine-oleic acid vesicles

The activity of the low molecular weight form of cytidylyltransferase from fetal lung cytosol and adult liver cytosol was stimulated more by phosphatidylcholine-oleic acid (1:1 molar ratio) vesicles than by phosphatidylglycerol vesicles. Phosphatidylcholine alone did not stimulate the activity, while oleic acid alone produced only slight stimulation. Vesicles prepared from phosphatidylinositol, phosphatidylglycerol-cholesterol (2:1) and phosphatidylglycerol-phosphatidylcholine (1:1) all stimulated the activity to the same extent. Phosphatidylcholine-oleic acid vesicles (molar ratio 2:1) produced less stimulation than 1:1 vesicles. Phosphatidylcholine-palmitic acid vesicles (2:1) were about 50% as active as the corresponding phosphatidylcholine-oleic acid vesicles. All vesicles were in the size range of small unilamellar vesicles as judged by Sephacryl S-1000 chromatography. Stimulation also occurred when phosphatidylcholine vesicles and oleic acid were added separately to the assay. The stimulation by phospholipid vesicles was correlated with the ability of the vesicles to bind cytidylyltransferase, determined by sucrose density centrifugation of the enzyme-vesicles mixtures. We conclude that the stimulation of soluble cytidylyltransferase occurs through binding of the enzyme to anionic membrane surfaces. Suitable anionic membranes can be prepared either from anionic phospholipids, or by the addition of anionic lipids (unesterified fatty acids or phosphatidylglycerol) to phosphatidylcholine.     

Toxigenic Potential of Some Fusarium Isolates from Southeast Asia

The isolation and characterization of 10 isolates of six Fusarium spp. from plant and soil samples collected in Southeast Asia is reported. The ability of these isolates to produce trichothecenes both in liquid cultures (CZ, GYEP, and MYRO) and on rice was assessed, and their toxigenic potential was examined by skin assay and gavage studies with culture filtrates. Although culture filtrates of all the isolates caused minor damage to test animals, only that of F. equiseti DAOM 189762 produced trichothecenes.     

Effect of amines on fibrinogen synthesis

L-Epinephrine, serotonin, and isoproterenol stimulate the incorporation of [14C]leucine into thrombin-induced clottable protein; this stimulation was abolished by actinomycin D. The incorporation of 32P into total RNA of rat liver, the site of fibrinogen synthesis, was stimulated by epinephrine and was highest at 2 h after 32P administration. [14C]Orotic acid incorporation into polysomal RNA of liver was also increased significantly by epinephrine and serotonin. The immunoprecipitation of newly synthesized protein by monospecific antibody raised against pure rat fibrinogen clearly demonstrates that L-epinephrine increased fibrinogen formation in vivo under the experimental condition. Translation of poly (A)-containing RNA from total polysomal RNA clearly indicates that L-epinephrine increased mRNA specific for fibrinogen.     

Retinoic acid modulation of 1,25(OH)2 vitamin D3 receptors and bioresponse in bone cells: species differences between rat and mouse

Retinoic acid (RA) caused a reduction in the level of 1,25(OH)2D3 receptors to 1/3 of control in rat osteoblast-like cells (ROB) while increasing the receptor level to 3-fold the control in mouse osteoblast-like cells (MOB). Scatchard analysis of receptor binding indicated that there was no change in affinity for 1,25(OH)2D3. The changes in receptor levels required time to develop and were dose-dependent. RA also modulated the ability of cells to respond to 1,25(OH)2D3 as measured by the induction of the enzyme 25(OH)D3-24 hydroxylase. Induction of enzyme activity by 1,25(OH)2D3 closely paralleled receptor level established by RA pretreatment. In MOB, the up-regulation of the receptor occurred despite the action of RA to inhibit DNA, RNA and protein synthesis. However, RA stimulation of 1,25(OH)2D3 receptor levels was blocked by the addition of cycloheximide or actinomycin D, indicating that the up-regulation required protein and RNA synthesis. The opposite effect of RA on mouse and rat cells suggests that important species-dependent factors modulate the action of retinoids on mammalian cells.     

Expression of adult female patterns of sexual behavior by male, female, and pseudohermaphroditic female rhesus monkeys

Gonadally intact pseudohermaphroditic female and normal female and neonatally castrated male rhesus monkeys were given estrogen treatment as adults and evaluated for attractivity, proceptivity, and receptivity during tests with a tethered stud male. Pseudohermaphrodites were produced by injecting their mothers during pregnancy with either testosterone propionate (TP) or dihydrotestosterone propionate (DHTP). Castrated males had reliably lower attractivity than normal females on all indicator responses shown by the tethered males. Additionally, castrated males showed reliably fewer proceptive responses on 4 of 5 measures than normal females. Receptivity could not be assessed in this situation for castrated males, because tethered males never contacted them unless the castrated males were displaying presentation. No reliable differences were observed between pseudohermaphrodites produced by prenatal treatments with TP or DHTP. Pseudohermaphrodites generally showed reliably less attractivity and proceptivity than normal females and reliably more of these traits than castrated males. Attractivity scores for pseudohermaphrodites were not different from those for normal females until proximity to the tethered male was established. Receptivity was not different in pseudohermaphrodites compared with normal females. Results indicate prenatal androgenization and its developmental sequelae lead to a defeminization in adulthood which, in this testing situation, was principally manifested by a deficiency in the performance of proceptive behaviors. Additionally, defeminization in rhesus monkeys, unlike that demonstrated in rodents, does not depend upon actions of an aromatizable androgen.     

Immunochemical analysis of the types Ia and Ib group B streptococcal polysaccharides

The types Ia and Ib group B streptococcal type-specific polysaccharides have remarkable immunologic differences despite a great deal of structural similarity. Although these two complex polysaccharides differ only by a single glycosidic linkage, they are antigenically distinct. Furthermore, terminal sialic acid residues appear to be critical to the immunodeterminant on the type Ia polysaccharide, whereas the antigenicity of the type Ib polysaccharide does not show this dependence on sialic acid. In the current investigation we defined better the immunodeterminant of these polysaccharides. With homologous rabbit antiserum, the type Ia native and core polysaccharides demonstrated partial serologic identity, whereas the type Ib native and core polysaccharides demonstrated complete serologic identity. Surprisingly, the type I degalactosylated polysaccharide, degraded structure, was capable of reacting with a population of antibodies present in type Ia antiserum similar to the complete type Ia native polysaccharide, although demonstrating a reduced level of immunodeterminant expression. Unlike the reactions of the type Ia polysaccharides with homologous rabbit antiserum, the Ib native and core polysaccharides were able to react with identical populations of antibodies in type Ib-specific antiserum. A minor population of antibodies was demonstrated in the type Ib antiserum, which was reactive with the degalactosylated polysaccharide. That a population of antibodies reactive toward the degalactosylated polysaccharide is present in both type Ia and type Ib antisera suggests that the Iabc cross-reacting determinant is due to the presence of serum antibodies reactive with this trisaccharide repeating unit, which is shared by both the type Ia and the type Ib native and core polysaccharides.     

Substrate and inhibitor specificity of anion exchangers on the brush border membrane of rabbit ileum

Summary In previous studies we have found that several anions can be transported by an exchange process in rabbit ileal brush border membranes. We demonstrated exchanges of Cl for OH or HCO₃, SO₄ for OH, oxalate for OH, and oxalate for Cl. The purpose of these studies was to determine the number of distinct carriers mediating these exchanges. We utilized substrate and inhibitor specificity studies to distinguish between different anion exchange transporters. We conclude that SO₄OH and oxalate: OH exchange occur on the same carrier because: (i) pH-gradient stimulated transport of both¹⁴C-oxalate and³⁵SO₄ were equally sensitive tocis-inhibition by unlabeled SO₄ or oxalate; and (ii) both were inhibited equally by K. We conclude that oxalate: OH and oxalate: Cl exchanges occur on different carriers because: (i) Cl or SO₄ caused unequalcis-inhibition of these two exchanges; and (ii) as compared to oxalate: Cl exchange, oxalate: OH exchange was more sensitive to inhibition by probenecid and K and less sensitive to inhibition by bumetanide. Finally, we conclude that oxalate: Cl exchange and ClHCO₃ exchange occur on different carriers because: (i) ClHCO₃ exchange was almost completely insensitive tocis-inhibition by oxalate; and (ii) oxalate: Cl exchange was more sensitive to inhibition by DIDS and bumetanide than ClHCO₃ exchange. Thus we have found that there are at least three separate anion exchangers on rabbit ileal brush border: (i) a ClHCO₃ exchanger; (ii) a SO₄OH exchanger, which also transports oxalate; and (iii) an oxalate: Cl exchanger.     

Hydrogen peroxide metabolism as an index of water stress tolerance in jute

Two species of jute plants Corchorus capsularis L. (cv. JRC 212) and C. olitorius L. (cv. JRO 632) were subjected to water stress for 2 and 4 days by withholding water. The relative water content (RWC) decreased in both plants under water stress but to a greater extent in C. olitorius . The C. olitorius seedlings also showed greater membrane injury than C. capsularis seedlings under water stress as was evident from injury index data. Water stress increased glycolate oxidase (EC 1.1.3.1.) activity more in C. olitorius than in C. capsularis . The activity of superoxide dismutase (SOD, EC 1.15.1.1.) and catalase (EC 1.11.1.6.) decreased under water stress and their decrease was higher in C. olitorius than in C capsularis . The level of hydrogen peroxide and lipid peroxidation also increased in both plants under water stress and the increase was higher in C. olitorius than in C. capsularis seedlings. Under comparable external water stress, C. capsularis seedlings showed lower membrane damage, lower H₂O₂ accumulation and lower lipid peroxidation than C. olilorius which may be taken as indicative of higher water stress tolerance capacity of the former.