Rapid determination of plasmid-carrying yeast cells by using an imaging sensor system

A novel imaging sensor system for the determination of plasmid carrying yeast cells was developed. The sensor system consisted of an Silicon Intensifier Target (SIT) video camera, a fluorescent microscope, and a personal computer system equipped with an image memory board. This system was based on the fact that the membrane integrity of only plasmid-carrying cells is lost following cell growth in 5-fluoro-orotic acid (5-FOA) containing medium, and consequently these target cell can be stained with fluorescent probes and detected. In this study, plasmid-carrying cells were detected and their fraction determined in a mixture of both plasmid-carring and plasmid-free cells. A good correlation was observed between the values determined by this sensor system and the conventional method in the 30%-80% range, and one assay was possible within 4 h. This sensor system could be used for the monitoring of plasmid-carrying fraction in recombinant yeast cells during cultivation.     

Industrial enzymes--developments in production and application

The utilization of gene technology and of new production technologies have made industrial enzymes with improved properties or better cost performance available. This has in turn opened important new areas of enzyme applications. The benefits to the customers are considerable: cost savings in the application process, improved product quality, and in most cases also a significantly reduced impact on the environment.

Gene technology offers several benefits to the enzyme industry. This technology enables the use of safe, well-documented host organisms easy to cultivate, the microbial production of enzymes of animal and plant origin, the realization of enhanced efficiency and high product purity, and also the production of enzymes with improved stability and activity.

Developments in production technology include advanced control methods, the use of expert systems, and the application of large-scale crystallization.

As case stories the development of a lipase and of a cellulase is described. The effect on environment of enzyme application and production is discussed.     

Circular dichroism detection in HPLC

A circular dichroism-based detection system presents several advantages in the HPLC analysis of chiral compounds because of the selective monitoring of optically active molecules. Its use allows reliable determination of enantiomeric excesses and elution order. To this end, the application of empirical, semiempirical, and nonempirical methods to get stereochemical information from the CD signal is reported. Furthermore, recording the CD spectra on line and evaluation of the dissymetry factor make the CD detection very powerful in characterizing the stereochemistry of chiral eluates.     

Tyrosine Hydroxylase Activity in Rat Brain Synaptosomes: Direct Measurement Using High Performance Liquid Chromatography

Abstract: By use of high performance liquid chromatography with electrochemical detection to measure dopamine production, tyrosine hydroxylase (EC 1.14.16.2) activity has been measured in rat brain synaptosomes from striatum and forebrain. Normal specific activities three- to fivefold higher than previously reported in the literature for radiochemical methods of assay were found. It is suggested that synaptosomes contain a significant amount of endogenous substrate for tyrosine hydroxylase, which causes dilution of the added labelled tyrosine and hence underestimation of the activity of this enzyme when radiochemical methods are used.     

A Rapid and Simple Method for the Determination of Picogram Levels of 3-Methoxytyramine in Brain Tissue Using Liquid Chromatography with Electrochemical Detection

Abstract: A rapid and simple technique using solvent extraction, ion-pairing extraction, and high pressure liquid chromatography with electrochemical detection has been developed for the determination of 3-methoxytyramine in striata of rats killed by microwave irradiation. The method is specific and reproducible (coefficient of variation among replications, ±4%); recovery of authentic 3-methoxytyramine added to the samples is 45–50%. 3-Methoxytyramine levels found with this technique in rat striata were 15 ± 1.7 ng/g. The method has a sensitivity of about 0.2 pmol per brain sample. Monoamine oxidase inhibition with pargyline increased 3-methoxytyramine levels in rat striata, while catechol- O -methyltransferase inhibition with 3',4'-dihydroxy-2 methylpropiophenone completely depleted 3-methoxytyramine. The effects of nomifensine, quipazine, caroxazone, piribedil, and D-amphetamine were also examined. The 3-methoxytyramine concentrations in the brains of animals killed by decapitation or by microwave irradiation were compared.     

The role of causal knowledge in the evolution of traditional technology

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