Comparative immunological characterization of various photosynthetic cytochromes c from pro- and eukaryotic algae

Photosynthetic c-type cytochromes isolated from various pro- and eukaryotic algae have been compared by an immunochemical method. Thereby the extent of cross-reactivity of several cytochromes with antisera to cytochrome c from Spirulina platensis, Bumilleriopsis filiformis, and Scenedesmus acutus was quantitatively determined by antigen-binding tests. When immunological relationship is taken as a measure of structural relationship, the following conclusions can be drawn: (1) c-type cytochromes from Anabaena variabilis, Nostoc muscorum, Calothrix membranacea, and Spirulina platensis show large differences in cross-reactivity. (2) The acidic Spirulina cytochrome c is fairly closely related to the two eukaryotic cytochromes assayed here.Abbreviations SAUG Sammlung von Algenkulturen am Pflanzenphysiologischen Institut der Universität Göttingen, FRG - PCC Pasteur Culture Collection     

Automated method for determination of glutardialdehyde residues in flexible endoscopes after disinfection

Glutardialdehyde (GDA) is the most commonly used disinfectant for flexible endoscopes. After inappropriate rinsing of endoscopes residual GDA in the narrow endoscope channels may lead to toxic effects in patients. Common methods for determination of aldehydes in water involve derivatization with 2,4-dinitrophenylhydrazine (DNPH), liquid-liquid or solid-phase extraction and HPLC determination. Since derivatization and extraction is both time-consuming and labor-intensive only a small number of samples can be measured. Thus, we developed a fully automated method which includes a conventional HPLC system, a programmable autosampler, and UV detection. After GDA derivatization using DNPH the samples remain in the aqueous phase and no preconcentration of the analyte is necessary. The samples are automatically derivatized through the autosampler. While derivatization in one sample takes place the previous sample is injected and measured by HPLC. Our method is well suited for screening residual GDA in endoscopes as it is both time- and labor-saving.     

Biosynthesis of calystegines: 15N NMR and kinetics of formation in root cultures of Calystegia sepium

Calystegines are nortropane alkaloids bearing between three and five hydroxyl groups in various positions. [15N]Tropinone was administered to root cultures of Calystegia sepium and the incorporation into calystegines was followed. Increase of label in calystegines was measured by one-dimensional 15N NMR and inverse-detected 2D NMR techniques. The results show that tropinone and pseudotropine are metabolites in the biosynthetic pathway of calystegines. The velocity of calystegine accumulation was followed kinetically by transfer of root cultures from 15N-enriched medium to 14N-medium and analysis by GC-MS. A constant calystegine formation with no interference by excretion or degradation was observed. A biosynthetic rate for individual calystegines at each time point was calculated, the maximum was 0.4 mg/day/g of biomass. This allowed the velocity of individual biosynthetic steps to be estimated.     

Effects of dietary supplementation of nickel and nickel-zinc on femoral bone structure in rabbits

Background  

Nickel (Ni) and zinc (Zn) are trace elements present at low concentrations in agroecosystems. Nickel, however, may have toxic effects on living organisms and is often considered as a contaminant. This study reports the effect of peroral administrated Ni or a combination of Ni and Zn on femoral bone structure in rabbits.     

Membrane renewal after dibucaine deciliation of Tetrahymena: Freeze-fracture technique,cilia, membrane structure

Axenic late log phase cultures of Tetrahymena pyriformis DN-B3 are deciliated by treatment with dibucaine. Deciliation occurs first at the anterior end of the cell and then progresses posteriorly. Concomitantly, all mature mucocysts are induced to discharge by the drug. The exact point of scission of each cilium is found to be a very localized region, between two specialized membrane arrays: the ciliary necklace and the ciliary patches, situated at the base of the cilium. Isolated cilia retain the patches, while the necklaces remain with the deciliated bodies. The cell membrane seals over the stubs. The new ciliary membrane then grows out above the necklace without the patches, which do not generally appear for several hours. Membrane renewal is therefore asynchronous, with bulk growth preceding the formation of specialized intramembrane particle arrays. During regrowth, the cilia also first return at the anterior end of the cell. This suggests that underlying gradients, perhaps related to Ca²⁺, are significant in the deciliation process.     

The bacterial paromomycin resistance gene, aphH, as a dominant selectable marker in Volvox carteri

The aminoglycoside antibiotic paromomycin that is highly toxic to the green alga Volvox carteri is efficiently inactivated by aminoglycoside 3′-phosphotransferase from Streptomyces rimosus. Therefore, we made constructs in which the bacterial aphH gene encoding this enzyme was combined with Volvox cis-regulatory elements in an attempt to develop a new dominant selectable marker – paromomycin resistance (Pm^R) – for use in Volvox nuclear transformation. The construct that provided the most efficient transformation was one in which aphH was placed between a chimeric promoter that was generated by fusing the Volvox hsp70 and rbcS3 promoters and the 3′ UTR of the Volvox rbcS3 gene. When this plasmid was used in combination with a high-impact biolistic device, the frequency of stable Pm^R transformants ranged about 15 per 10⁶ target cells. Due to rapid and sharp selection, Pm^R transformants were readily isolated after six days, which is half the time required for previously used markers. Co-transformation of an unselected marker ranged about 30%. The chimeric aphH gene was stably integrated into the Volvox genome, frequently as tandem multiple copies, and was expressed at a level that made selection of Pm^R transformants simple and unambiguous. This makes the engineered bacterial aphH gene an efficient dominant selection marker for the transformation and co-transformation of a broad range of V. carteri strains without the recurring need for using auxotrophic recipient strains.