Quantitative measurement of oxygen consumption in insect cell culture infected with polyhedrosis virus

A simple and reproducible quantitative method for measuring dissolved oxygen (DO) in uninfected and baculovirus infected cells in culture is described. To establish this method, an industrial DO measuring system for fermentation was employed. During this process the physical characteristics of the cell culture vessel were taken into account permitting a direct readout of DO in microliters per vessel. During these studies, it was experimentally documented that insect cells, particularly baculovirus infected cells, in culture from 1 to 14 days utilize an appreciable level of DO.     

Erythritol as a Selective Substrate for the Growth of Serratia marcescens

Serratia marcescens grew on a basal medium containing 0.5% erythritol as sole source of carbon for growth and energy. Only an occasional strain of Enterobacter aerogenes among several members of the family Enterobacteriaceae were able to utilize erythritol.     

Chemical geometrodynamics: Physical fields can cause asymmetric synthesis

This paper presents theoretical arguments that suggest that chiral combinations of physical fields which can induce motion of elementary particles or molecular systems can in principle cause asymmetric synthesis. The theory is founded on the application of parity and time reversal operators to chiral dynamical systems. The motion of these systems induced by a chiral set of physical fields is shown not to be invariant on parity and time reflection. The relationship between tetrahedral dissymmetry and belical dissymmetry is analyzed in terms of the moments of inertin of a tetrahedrally dissymmetric rotor rotating around each of the four bond axes. The magnitude of anticipated enantiomeric excess which would result from conducting a prochiral chemical reaction in a chiral set of physical fields is estimated to be very small, parts per million or less, for virtually all sets of readily accessible physical fields. The results of experiments in which prochiral chemical reactions were conducted in a sealed tube which was spinning perpendicular or paralled to the earth's surface, are reviewed as are experiments in which prochiral chemical reactions were conducted in intense oriented magnetic fields. Enantiomeric recognition may have been one of the principal mechanisms for amplifying small differences in the rates of a given prochiral chemical reaction.     

A spectrophotometric method for the assay of phospholipase D activity

Phosphatidylcholine phosphatidohydrolase (EC 3.1.4.4, phospholipase D) catalyzes the hydrolysis of phosphatidylcholine to phosphatidic acid and choline. We have developed a spectrophotometric assay for phospholipase D using choline kinase, pyruvate kinase, and lactate dehydrogenase to couple the release of choline with the oxidation of NADH. The assay was linear both with time and with enzyme concentration. The assay should prove useful for continuous monitoring of enzyme activity, determination of initial rates of reaction, and detailed kinetic studies of phospholipase D. The method is limited to analysis of purified preparations of phospholipase D lacking competing activities to the coupled system.     

Effect of aluminum chloride and zinc sulfate on Autographa california nuclear polyhedrosis virus (ACNPV) replication in cell culture

When IPL-SF-21AE III continuous insect cell line was grown and maintained in IPL-41 insect cell culture medium supplemented with 16 microM of AlCl3 or 0.24 microM of ZnSO4 . 7H2O, or both metallic salts, and then infected with Autographa california nuclear polyhedrosis virus, virus replication was increased significantly. The yield of polyhedral inclusion bodies (PIB) was enhanced up to 121%. Synthesis of cell-free nonoccluded virus was increased to 365% when infectivity was assayed by the plaque method. Newly applied electron microscopic quantitation and stereological techniques also revealed a significant increase in virus particles (VP) and in amount and size of PIB as well as number of VP per PIB.     

Expression of a 16,000 molecular weight antigen on human suppressor T lymphocytes

When SJL mice are irradiated and reconstituted with syngeneic bone marrow (XBM) they support growth of transplantable reticulum cell sarcoma to approximately 60% of that in normal mice. The ability to support RCS growth gradually improves with time after irradiation and reaches 90% of normal by 8–12 weeks. However, if the mice are thymectomized 4 weeks prior to treatment (Tx-XBM) they initially show 50% which increases to only 65% of growth in normal mice after 12 weeks. The ability of lymphoid cells from these mice to proliferate in vitro in response to irradiated RCS cells is normal 4 weeks after treatment in XBM, but remains <10% of normal in Tx-XBM mice. Nude mice of SJL background also show greatly diminished RCS growth. It is concluded that T cells promote RCS growth in vivo possibly via their tendency to proliferate upon exposure to RCS.     

New Views of Multi-Ion Channels

The rate constants of acetylcholine receptor channels (AChR) desensitization and recovery were estimated from the durations and frequencies of clusters of single-channel currents. Diliganded-open AChR desensitize much faster than either unliganded- or diliganded-closed AChR, which indicates that the desensitization rate constant depends on the status of the activation gate rather than the occupancy of the transmitter binding sites. The desensitization rate constant does not change with the nature of the agonist, the membrane potential, the species of permeant cation, channel block by ACh, the subunit composition (ε or γ), or several mutations that are near the transmitter binding sites. The results are discussed in terms of cyclic models of AChR activation, desensitization, and recovery. In particular, a mechanism by which activation and desensitization are mediated by two distinct, but interrelated, gates in the ion permeation pathway is proposed.     

The Escherichia coli mutant requiring D-glutamic acid is the result of mutations in two distinct genetic loci.

D-Glutamic acid is an essential component of bacterial cell wall peptidoglycan in both gram-positive and gram-negative bacteria. Very little is known concerning the genetics and biochemistry of D-glutamate production in most bacteria, including Escherichia coli. Evidence is presented in this report for the roles of two distinct genes in E. coli WM335, a strain which is auxotrophic for D-glutamate. The first gene, which restores D-glutamate independence in WM335, was mapped, cloned, and sequenced. This gene, designated dga, is a previously reported open reading frame, located at 89.8 min on the E. coli map. The second gene, gltS, is located at 82 min. gltS encodes a protein that is involved in the transport of D- and L-glutamic acid into E. coli, and the gltS gene of WM335 was found to contain two missense mutations. To construct D-glutamate auxotrophs, it is necessary to transfer sequentially the mutated gltS locus, and then the mutated dga locus into the recipient. The sequences of the mutant forms of both dga and gltS are also presented.