Particulate Glucan Synthetase Activity: Dependence on Acceptor, Activator, and Plant Growth Hormone

Particulate fractions isolated from the growing region of the epicotyl of Pisum sativum L. var Alaska are capable of transferring glucose from uridine or guanosine diphosphate glucose-14C to buffer-insoluble products which are partly alkali-soluble and partly alkali-insoluble. Cellobiose activates the reaction; carboxymethylcellulose and cellodextrins act as competitive acceptor molecules.When the epicotyl is decapitated, glucan synthetase activity disappears from particulate fractions of the growing region within 3 days unless the hormone indoleacetic acid (IAA) is added to the tissue, in which event activity is retained. Other growth regulators (gibberellic acid, benzyladenine) have no such effect. Loss of activity is not due to a change in solubility of enzyme or product or to the absence of substrate, activator, or acceptor molecules, nor is it accompanied by comparable losses in total protein or cellulase activity from the particulate fraction. It is concluded that IAA is needed for the formation and/or protection of an essential part of the insoluble synthetase complex. </jats:p

Circulating immune complexes in patients with acute measles and rubella virus infections

A solid-phase C1q radioimmunoassay was used to test for immune complexes (ICs) in sera obtained longitudinally from patients recovering from acute, uncomplicated measles and rubella virus infections. ICs were detected in 12 (18.5%) of 65 sera from 14 measles patients who did not have prolonged IC formation. Of 12 IC-positive measles sera, 9 were collected 4 weeks or more after rash onset. Transient appearance of detectable circulating ICs occurred sooner in 22 rubella patients who did not have prolonged IC formation. Of 109 rubella sera, 14 (12.8%) were IC-positive, and, of these, 10 were collected within 3 weeks of rash onset. Prolonged IC formation was found for an additional four measles and two rubella virus patients. Fractionation of sera from these six patients revealed that levels of large-sized ICs were highest in the initial 10 days after rash onset. Levels of large-sized ICs then declined to those for medium- and small (approximately immunoglobulin G)-sized ICs. IC-associated virus-specific antigens were detected in some of the sera from the six patients having prolonged IC formation. These results suggest two things: first, measles and rubella virus patients differ in the timing of virus clearance or in the reestablishment of normal immunity after infection; second, virus clearance is prolonged in some measles and rubella virus patients who have seemingly normal recoveries from their infections.</jats:p

Detection of Pediococcus spp. in brewing yeast by a rapid immunoassay

A membrane immunofluorescent-antibody test was developed to detect diacetyl-producing Pediococcus contaminants in brewery pitching yeast (yeast [Saccharomyces cerevisiae] slurry collected for reinoculation). Centrifugations at 11 and 5,100 x g separate yeast cells from bacteria and concentrate the bacteria, respectively. Pelleted bacteria resuspended and trapped on a black membrane filter are reacted with monoclonal antibodies specific for cell surface antigens and then with fluorescein-conjugated indicator antibodies. Whether pitching yeast is contaminated with pediococci at 0.001% is determined in less than 4 h. The sensitivity of the assay is 2 orders of magnitude below the Pediococcus detection limit of direct microscopy.</jats:p