Date Palm DNA Mini-Preparation without Liquid Nitrogen

We have developed a new mini-procedure for isolation of total cellular DNA from date palm (Phoenix dactylifera L.). The procedure, which does not use liquid nitrogen, has proved useful due to temporary disruptions in supplies of liquid nitrogen that occur in countries where date palm trees are cultivated. DNA suitable for RFLP and PCR analyses is obtained.     

State-of-the art data normalization methods improve NMR-based metabolomic analysis

Extracting biomedical information from large metabolomic datasets by multivariate data analysis is of considerable complexity. Common challenges include among others screening for differentially produced metabolites, estimation of fold changes, and sample classification. Prior to these analysis steps, it is important to minimize contributions from unwanted biases and experimental variance. This is the goal of data preprocessing. In this work, different data normalization methods were compared systematically employing two different datasets generated by means of nuclear magnetic resonance (NMR) spectroscopy. To this end, two different types of normalization methods were used, one aiming to remove unwanted sample-to-sample variation while the other adjusts the variance of the different metabolites by variable scaling and variance stabilization methods. The impact of all methods tested on sample classification was evaluated on urinary NMR fingerprints obtained from healthy volunteers and patients suffering from autosomal polycystic kidney disease (ADPKD). Performance in terms of screening for differentially produced metabolites was investigated on a dataset following a Latin-square design, where varied amounts of 8 different metabolites were spiked into a human urine matrix while keeping the total spike-in amount constant. In addition, specific tests were conducted to systematically investigate the influence of the different preprocessing methods on the structure of the analyzed data. In conclusion, preprocessing methods originally developed for DNA microarray analysis, in particular, Quantile and Cubic-Spline Normalization, performed best in reducing bias, accurately detecting fold changes, and classifying samples.

     

A tracer method to study unidirectional fluxes of lithium: Application to frog skin

We describe a new tracer method to measure unidirectional fluxes of Li⁺, despite the lack of any utilizable radioisotope of lithium. This method uses the purified stable isotopes, ⁶Li and ⁷Li, detected with an ion-probe microanalyser. The accuracy is comparable to that obtained for other ions (e.g., Na⁺) with radiotracers.The method has been applied to frog skin with both faces bathed in a 20% lithium/80% sodium medium. Sodium and lithium unidirectional fluxes have been measured simultaneously. The results are consistent with lithium being actively pumped, the outflux of lithium being, however, much larger than that of sodium.     

Time course of pump inhibition by ouabain in amphibian epithelia

Inhibition by ouabain of rheogenic Na⁺ transport across the basolateral membranes of frog skin is found to be manifest within 3–4 min. This rate of pump inhibition is not different from the rate of diffusion through extracellular tissue layers between the serosal bath and the actual site of action, i.e., the epithelial cell layers. It is concluded that the well-known slow time course of decrease in transepithelial current flow is due ionic redistribution and conductance changes of the epithelial membranes secondary to pump inhibition.     

Versuche zum Herbizideinsatz in gesäten Kohlarten

In den Jahren 1987 bis 1989 wurden die Auswirkungen und Effekte eines kombinierten Befalls des Winterweizens mit Sitobion avenae (Fabr.) und Puccinia recondita Rob.ex Desm. f.sp.tritici Erikss. untersucht. Dabei wurde das Verhalten der Schaderregerpopulationen und die Einflußnahme auf das Ertragsgeschehen bei separatem und simultanem Befall erfaßt. Während bei starkem Befall der oberen Blattetagen mit P.recondita eine Förderung der Aphidenpopulation an den Ähren der befallenen Pflanzen registriert werden konnte, war bei schwachem Braunrostbefall keine Einflußnahme auf die Blattläuse nachweisbar. Durch das kombinierte Auftreten beider Schaderreger kann es zu Reduktionen bei der Kornmasse/Ähre und bei der Tausendkornmasse kommen, die größer sind, als die Summe der Verluste bei Einzelbefall. Ähren stark braunrostbefallener Winterweizenpflanzen wurden zeitiger von S.avenae angeflogen und schneller besiedelt als diese von gesunden Kontrollpflanzen. Als Ursache für die Förderung der Populationsentwicklung von S.avenae werden durch P.recondita induzierte Veränderungen im Angebot an freien Aminosäuren in der Wirtspflanze diskutiert.     

Ultrastructural demonstration of NAD-pyrophosphorylase activity in mouse liver nuclei.

Ultrastructural demonstration of NAD-pyrophosphorylase activity (E.C.2.7.7.1) in isolated mouse liver nuclei was investigated with the use of an electronhistochemical procedure based on the precipitation of pyrophosphate ions with lead ions under conditions permitting simultaneous ATPase inhibition by formaldehyde/ethanol prefixation. In isolated mouse liver nuclei activity of NAD-pyrophosphorylase was found in nucleoli, in interchromatin granules, coiled bodies and strand-like structures in nucleoplasm.