Determining serum bicarbonate; a simple syringe titrator and colorimeter

The use of a tuberculin syringe as a burette has made possible an easy bedside technique for the determination of serum bicarbonate. By combining it with the use of a simple colorimeter, a relatively untrained person can do numerous bicarbonate determinations with a high degree of accuracy. The same technique also lends itself to other colorimetric clinical procedures such as determination of gastric acidity.     

Spore production of Penicillium roqueforti by solid state fermentation: Stoichiometry, growth and sporulation behavior

The development of Penicillium roqueforti on buckwheat seeds proceeds roughly into four steps, involving a lag phase and three growth phases. First, it appears as a spore germination and external colonization of the grains by the mycelium. Then, mainly external sporulation and internal colonization of the seeds occur and finally internal sporulation takes place. The Stoichiometry of the growth and the sporulation is established. Kinetic experiments performed in a fixed bed reactor show that the growth of the microorganism (biomass production) may be estimated by the protein content of the medium. This growth occurs with a very low mu(max) value close to 0.030 h(-1). The chitin content of the medium is an indicator of the sporulation, just as the metabolic liquor (mainly water) produced during the course of a cultivation. The values of the observed respiratory quotient are close to those predicted by stoichiometry.     

Rapid in Vivo Acylation of Acyl Carrier Protein with Exogenous Fatty Acids in Spirodela oligorrhiza

Posttranslational acylation of several chloroplast proteins with palmitic acid was recently demonstrated in Spirodela oligorrhiza (AK Mattoo, M Edelman [1987] Proc Natl Acad Sci USA 84: 1497-1501). We have now identified an in vivo acylated, soluble protein having an apparent M_r of 10 kilodaltons on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as an acylated form of acyl carrier protein (ACP). This 10-kilodalton protein is present in low abundance, and its acylation is light-stimulated. Turnover of the acyl moiety but not the apo-protein is rapid in the light. The acylated 10-kilodalton protein coelectrophoreses with in vitro synthesized palmitoyl-acyl carrier protein and is immunoprecipitated from soluble extracts with an antibody raised against spinach ACP. Cerulenin, an inhibitor of β-ketoacyl-ACP synthetase, inhibited in vivo acylation of Spirodela ACP. Cell-free extracts of Spirodela plants were able to catalyze the transfer of palmitate from palmitoyl-CoA to ACP, suggesting the existence in higher plants of a pathway for acylation of ACP that involves transacylation from acyl-CoA.     

Chemotaxis toward Nitrogenous Compounds by Swimming Strains of Marine Synechococcus spp

Many of the open-ocean isolates of the marine unicellular cyanobacterium Synechococcus spp. are capable of swimming motility, whereas coastal isolates are nonmotile. Surprisingly, the motile strains do not display phototactic or photophobic responses to light, but they do demonstrate positive chemoresponses to several nitrogenous compounds. The chemotactic responses of Synechococcus strain WH8113 were investigated using blind-well chemotaxis chambers fitted with 3.0-mum-pore-size Nuclepore filters. One well of each chamber contained cells suspended in aged Sargasso Sea water, and the other well contained the potential chemoattractant in seawater. The number of cells that crossed the filter into the attractant-seawater mixture was measured by direct cell counts and compared with values obtained in chambers lacking gradients. Twenty-two compounds were tested, including sugars, amino acids, and simple nitrogenous substrates, at concentrations ranging from 10 to 10 M. Strain WH8113 responded positively only to ammonia, nitrate, beta-alanine, glycine, and urea. Typically, there was a 1.5- to 2-fold increase in cell concentrations above control levels in chambers containing these compounds, which is comparable to results from similar experiments using enteric and photoheterotrophic bacteria. However, the threshold levels of 10 to 10 M found for Synechococcus spp. chemoresponses were lower by several orders of magnitude than those reported for other bacteria and fell within a range that could be ecologically significant in the oligotrophic oceans. The presence of chemotaxis in motile Synechococcus spp. supports the notion that regions of nutrient enrichment, such as the proposed microzones and patches, may play an important role in picoplankton nutrient dynamics.     

Affinity-specific protein separations using ligand-coupled particles in aqueous two-phase systems: I. Process concept and enzyme binding studies for pyruvate kinase and alcohol dehydrogenase from Saccharomyces cerevisiae

A process using ligand-coupled particles in aqueous polyethylene glycol-dextran two-phase polymer systems was developed to achieve a highly selective, scaleable biochemical separation process. Product protein is bound to the ligand-coupled particles that quantitatively distribute to the polyethylene glycol-rich upper phase. Other proteins and contaminants partition preferentially to the dextran-rich lower phase.The process offers significant advantages over affinity partitioning here the ligand is coupled to the backbone of a polyethylene glycol polymer. These advantages include a much wider diversity of ligands that can be coupled to particles and more effective confinement of the ligand in the process. Affinity partition with ligands coupled to particles is more amenable to scale-up than is affinity chromatography. A variety of commercially available Sepharose-based particles are suitable for this process. Homogenates from Saccharomyces cerevisiae, which is genetically altered to overproduce pyruvate kinase, and Cibacron blue F3G-A-coupled Sepharose particles are used as a model system for the process. Binding studies with/without aqueous two-phase systems show that the formation of a two-phase system after the adsorption equilibrium is reached does not affect the apparent dissociation constant. Binding of protein to ligand-coupled particles is more rapid in single-phase systems than in the polymer two-phase system. Single-phase binding eliminates the mass transfer resistance associated with redistribution of product protein from the dextran-rich bottom phase to the polyethylene glycol-rich top phase.     

How suspension cultures of Catharanthus roseus respond to oxygen limitation: small-scale tests with applications to large-scale cultures

The effect of oxygen supply on the growth of suspension cultures of Catharanthus roseus in Erlenmeyer flasks was investigated. Below a critical oxygen supply rate the culture could not survive. By increasing the oxygen supply, a point is reached where the culture survives but no growth is possible. At higher oxygen supply rates there is a regime where both growth rate and the maximum biomass concentration increase with oxygen supply. Eventually there comes a point where no further increase in biomass is achieved, probably due to the depletion of the sugars; however, the growth rate continues to increase with oxygen supply until a maximum growth rate is obtained. The ratio of fresh to dry weight at maximum fresh weight increased with shaker table speed of rotation accompanied by a greater rate of sugar depletion.     

Fixed bed porous glass sphere (porosphere) bioreactors for animal cells

Process intensity of fixed bed glass sphere culture systems is increased considerably by replacing solid glass spheres with open pore glass spheres. This technique demonstrates the possibility of having a system capable of both volumetric and cell density scale up and being suitable for substrate attached and suspension cells. The yields achieved for a number of attached cell lines (approximately 10⁷/ml) demonstrate an increase approaching one order of magnitude over solid glass spheres (approximately 10⁶/ml). Also suspension cells were successfully entrapped in the open pore structure with similar yields.