The role of trehalose in the osmoadaptation of Escherichia coli NCIB 9484: interaction of trehalose, K+ and glutamate during osmoadaptation in continuous culture.

Natural abundance 13C nuclear magnetic resonance spectroscopy identified the disaccharide trehalose as the major organic osmolyte synthesized by Escherichia coli grown in continuous culture under nitrogen limitation in the presence of 0.5 M-NaCl. Trehalose accumulation was dependent on both the growth phase of the culture and the osmolality of the growth medium, but independent of the solute used to increase the osmolality as long as the solute was non-penetrant. The penetrant solute glycerol did not induce trehalose synthesis indicating that the loss of cell turgor rather than increasing medium osmolality per se was the mechanism stimulating trehalose synthesis. Under conditions of either carbon or nitrogen limitation osmoadaptation was distinctly biphasic. The initial response consisted of a rapid (within 30 min) accumulation of K+ and a concurrent synthesis of the amino acid glutamate; trehalose synthesis occurred during the second slower phase of osmoadaption. Chloramphenicol severely inhibited trehalose accumulation indicating that the enzyme(s) involved in trehalose synthesis were inducible.     

High osmotic stress behavior of hyaluronate and heparin.

Using polyethylene glycol and dextran as osmotic stressing agents, the concentrations of hyaluronate and heparin were measured as a function of osmotic pressure II over the range of 0.03 to nearly 50 atmospheres. The experimental results were analyzed in terms of the Donnan osmotic pressure, the virial expansion, and Flory's first neighbor interaction parameter. In addition, II was looked at as a function of the reciprocal cube root of the concentration, which represents an average intermonomer spacing at high concentrations. The decay lengths in the so-called hydration region were found to be around 2.6 A and negligibly salt dependent. In the electrostatically dominated region the decay lengths were found to be dependent on the ionic strength, but not simply so. The osmotic compressibilities were also calculated, and were compared to compressibility data of corneal stroma and articular cartilage. These latter compressibilities were close to those for the pure hyaluronate and heparin, strengthening the evidence that glycosaminoglycans (GAGs) are largely responsible for connective tissue compressibility. Higher compressibilities for previously reported GAG data is thought to be related to the protein content of those samples.     

MICROSPOROGENESIS IN PEANUT (ARACHIS HYPOGAEA)

The stage of pollen development at the time of anther culture is an important factor in the production of haploids. The objectives of the current study were to develop a staining procedure for peanut (Arachis hypogaea L., ssp. hypogaea) microspores, to describe and document the stages of microsporogenesis in peanut, and to confirm a previous report concerning correlations of peanut floral bud shape with stage of microspore development. A staining procedure using propionic carmine provided adequate staining of pollen mother cells, microspores, and pollen. Pollen mother cells and microspores could easily be differentiated by their size and cell wall structure. Plants grown in a controlled environment were found to have highly synchronized microspore development, both within an anther and among anthers contained in the same bud. In addition, floral bud shape was confirmed as a reliable indicator of anther stage in peanuts.     

Genetic variation at the immunoglobulin allotype loci in Creoles of Trinidad

The sera of a sample of 204 Creoles from Trinidad were tested for the presence of polymorphic gene complexes occurring on immunoglobulin light- and heavy-chain molecules including the allotypic markers IGKC 1, IGHA2 1 and 2, IGHG1 A, X, F, and Z, and IGHG3 G, G5, B0, B1, B3, B4, B5, C3, C5, S, and T. Nine IGHG (GM) haplotypes occur in polymorphic frequencies (greater than .01) in this population, including known African, Asian, Caucasian, and Amerindian marker haplotypes. Significant differences (P less than .01) were found in the frequency distributions of three IGHG (GM) haplotypes and the frequency of IGKC*1 in these data and data from Creole populations of Belize and St. Vincent. The Creoles of Trinidad and St. Vincent are more similar in IGHG (GM) haplotype distributions than are Trinidad and Belize populations. Previous testing has revealed no significant differences between St. Vincent and Belize Creoles at the Ig allotypic loci. Analysis of migration patterns in the Caribbean suggests that different rates of Asian migration have maintained regional diversity at these loci, while continuous gene flow from the eastern Caribbean to Trinidad has had a relative homogenizing effect on the gene pools of this area.     

Glutathione biosynthesis in murine L5178Y lymphoma cells

The pyruvate dehydrogenase complex from pea leaf mitochondria was rapidly deactivated in the presence of 50 to 200 μm ATP. The deactivation of the complex requires Mg²⁺ as shown by EDTA inhibition of deactivation. Deactivation was inhibited by 0.1 to 1 mm pyruvate or dichloroacetate. Activation required 10 mM Mg²⁺ or Mn²⁺ but Ca²⁺ and K⁺ had no effect. Activation was inhibited by the phosphatase inhibitor, F^?. Autoradiograms of nondissociating electrophoresis gel, crossed immunoelectrophoresis gels, and dissociating sodium dodecyl sulfate electrophoresis gels of the complex showed that one protein is labeled. Labeling of this protein is prevented by Mg²⁺, pyruvate, and dichloroacetate. The pyruvate dehydrogenase complex was isolated in a partially deactivated state and reactivation required exogenous Mg²⁺ and was inhibited by F^?. These results are taken as conclusive evidence that the pyruvate dehydrogenase complex in pea leaf mitochondria undergoes interconversion between deactivated and activated states by covalent modification (phosphorylation-dephosphorylation) catalyzed by a kinase and phosphatase. Isolation of the complex in a partially deactivated (phosphorylated) state suggests a physiologically significant role for this regulatory mechanism.     

Evaluation of a new modified pediatric bubble oxygenator

A comparison was made of the S-070 Pediatric Bubble Oxygenator, which was unreliable above flow rates of approximately 1.5 L/min, with a modified S-070A, which proved to be extremely efficient to flow rates of 2.5 L/min.     

Trypanosoma musculi: Passive hemagglutination technique to measure antibody in mice

A passive hemagglutination assay was developed to measure Trypanosoma musculi-specific antibody in mice. Indicator-erythrocyte donor mice received 550 rad ⁶⁰Co 24 hr before intraperitoneal injection of 3 × 10⁴T. musculi. T. musculi antigen-coated erythrocytes were obtained from these mice on Day 9 postinfection. T. musculi antigen-coated erythrocytes obtained in this manner were used as indicator erythrocytes in a passive hemagglutination procedure. Serum from hyperimmunized mice (three consecutive infections at 21-day intervals) gave titers as high as 1:1024. Titers of 1:256 and 1:512 were obtained from singly infected mice on Days 18 and 28 postinfection, respectively. In marked contrast, nude mice infected with T. musculi did not produce a detectable agglutinating antibody response. Erythrocytes obtained from either irradiated (550 rad ⁶⁰Co) uninfected mice, nonirradiated infected mice, or normal mice did not agglutinate when combined with any of the sera tested. These data suggest the usefulness of this passive hemagglutination assay for the measurement of antibody to T. musculi in the serum of infected mice.     

Loss of choleragen receptors and ganglioside upon differentiation of 3T3-L1 preadipocytes

3T3-L1 preadipocytes differentiate in culture into cells having the enzymatic and morphological characteristics of adipocytes. Differentiation is accompanied by a decrease in total cellular ganglioside content; the ganglioside level is 1.8 to 2.5-fold higher in undifferentiated than in differentiated cells. Gangliosides GM3 and GD1a constitute a majority of total cell gangliosides in both cell types, while ganglioside GM1, the putative choleragen receptor, constitutes less than 5%. Differentiation results in a 75 to 85% decrease in ganglioside GM1. An inverse correlation exists between the percentage of adipocytes in the cell population and: 1) total ganglioside and ganglioside GM1 content, and 2) surface ganglioside GM1 as estimated by choleragen binding or fluorescent staining of bound choleragen. Nondifferentiating 3T3-C2 control cells do not exhibit changes in total ganglioside, ganglioside GM1, or choleragen binding that are observed with 3T3-L1 cells.     

A new species of Caulanthus (Cruciferae) from Nevada

Caulanthus barnebyi from northern Nevada is described, illustrated, and compared with its nearest relative,C. glaucus S. Wats.