Zur Taxonomie von Rhodopseudomonas palustris

Zusammenfassung Eine Reihe von Rhodopseudomonas palustris-Stämmen aus verschiedenen Herkünften wurden vergleichend unter Verwendung folgender Merkmale untersucht: Substratverwertung, in vivo-Absorptionsspektrum und Serologie der O-Antigene. Die gegen 2 Stämme gerichteten Antiseren zeigen hohe Spezifität. Die Verwendbarkeit der serologischen Kreuzreaktion für taxonomische Untersuchungen bei photosynthetischen Bakterien wird diskutiert.

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On the taxonomy of Rhodopseudomonas palustris

Summary Strains of Rhodopseudomonas palustris isolated from different habitats were compared with respect to their taxonomic features. All strains grew very well on formiate, acetate, propionate, butyrate, aspartate, inositol, ethanol, fructose, and p-amino-benzoate, respectively, as single carbon source. Most of the strains were able to use benzoic acid or glucose, too. But alanine was not found to be a good substrate. The maxima of the bacteriochlorophyll in-vivo-absorption spectra were estimated to be 376, 589, 802–805, and 858–875 nm. The shift of the infrared peak in the different strains is loosely correlated with the change of the carotenoid in vivo spectrum, the maxima of which were measured to be 470–480 nm (shoulder) 495–505 nm, and 520–545 nm (shoulder). Antisera were prepared against the strains 1e5 and 11/1. It was demonstrated that these antisera were directed against the lipopolysaccharides (O-antigen) of these bacteria. The antigen of 1e5 does not cross react with the antigen of 11/1. Strain 1e5 is the only one of 17 strains tested which is sensitive to the bacteriophage Rp1. The antigen of this strain cross reacted only with the antigen of strain K1. In contrast, the antigen of strain 11/1 cross reacted in some degree with most of the tested strains of Rps. palustris. No or very weak cross reaction was observed between the antigens of Rps. palustris (1e5, 11/1) and Rps. capsulata, Rps. spheroides, or R. rubrum, respectively. In contrast to 11/1 only heat-killed cells of strain 1e5 were agglutinated by anti-1e5.

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Im Text verwendete Abkürzungen LPS Lipopolysaccharid - R Rhodospirillum - Rps. Rhodopseudomonas - i.m. intramuskulär - s.c. subcutan - i.v. intravenös     

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.

     

Focal contacts of spreading platelets with the substratum

Contacts with glass substratum formed by the spreading rabbit platelets were examined by an antibody-exclusion method; monoclonal antibodies against 80 kD bovine serum protein were used. It was found that platelets form focal contacts in the course of spreading. The size of the largest focal contacts formed by platelets is smaller than that of the contacts formed by fibroblasts. The antibody-exclusion method revealed focal contacts of platelets much more clearly than interference reflection microscopy (IRM). The similarity of reactions involved in spreading platelets and of large nucleus-containing tissue cells is discussed.     

Separation of finasteride and analogues

This review is focused on the different chromatographic strategies for determination of finasteride and its analogues in biological fluids. These compounds are used for the treatment of benign prostatic hyperplasia. Particular attention is paid to high-performance liquid chromatography with spectrophotometric and mass spectrometric detection, the clean-up procedures are also included. The relationships between pharmacokinetics of finasteride, dose administered and required limit of quantitation of the chromatographic assays are discussed. Tandem mass spectrometry is recommended as the detection method for measuring concentrations <1 ng/ml, while cheaper spectrophotometric detection may be selected for determination of higher concentrations.     

Mutagenesis of hydroxylamine oxidoreductase in Nitrosomonas europaea by transformation and recombination.

Mutagenesis of Nitrosomonas europaea was achieved by electroporation and recombination. To demonstrate this, an aminoglycoside 3'-phosphotransferase (kan) gene was specifically inserted into each of the three gene copies of hao individually. Southern hybridizations and PCR analysis showed the incorporation of the kan gene at the chosen genetic loci. The isolation of mutant strains was achieved in 7 to 14 days when the strains were grown on solid medium. The induced mutations were stable even in the absence of kanamycin-selective pressure for periods of up to 45 days in culture. The mutant strains did not show an observable phenotype different from that of the wild type when grown under the same conditions.     

The occurrence and frequency of 2n pollen in 2x, 4x,and 6x wild,tuber-bearing Solanum species from Mexico,and Central and South America

Summary The occurrence of 2n pollen-producing plants was investigated in 187 plant introductions (PIs) of 38 wild species of tuber-bearing Solanum. These 2x, 4x, and 6x species are from Mexico, and Central and South America. The determination of 2n pollen-producing plants was conducted using acetocarmine glycerol. Plants with more than 1% large-size pollen were regarded as 2n pollen-producing plants. 2n pollen-producing plants were identified in the following species: 10 out of 12 Mexican 2x species, seven of nine South American 2x species, seven of seven Mexican and Central American 4x species, five of five South American 4x species, and five of five Mexican 6x species. The frequency of 2n pollen-producing plants varied among species at the same ploidy level, but the range of frequency, generally between 2 and 10% among species, was similar over different ploidy levels. The general occurrence of 2n pollen in both 2x and polyploid species, which are evolutionarily related, is evidence that the mode of polyploidization in tuber-bearing Solanums is sexual polyploidization. Furthermore, the frequencies of 2n pollen-producing plants in autogamous disomic polyploid species were not markably different from those of their related diploid species. It is thought that the frequent occurrence of 2n gametes with autogamy tends to disturb the fertility and consequently reduce fitness of polyploids. Thus, we propose that the breeding behavior of polyploids and the occurrence of 2n gametes may be genetically balanced in order to conserve high fitness in polyploid species in tuberbearing Solanum.Paper No. 3114 from the Laboratory of Genetics. Research supported by the College of Agriculture and Life Sciences; International Potato Center; USDA, SEA, CGRO 84-CRCR-1-1389; and Frito Lay, Inc.