Molecular and genetic characterisation of German families with paramyotonia congenita and demonstration of founder effect in the Ravensberg families

Eighteen German families with a history of paramyotonia congenita (PC) were characterised by genetic und mutational analysis at the SCN4A locus, which encodes the -subunit of the adult skeletal muscle sodium channel. We concentrated our analysis primarily on these families to test the hypothesis that a predominance of one common mutation occurs in all German PC families and that this mutation arose in a common ancestor originating in the North-West of the country. The present eighteen PC families exhibit two different mutations (R1448C and R1448H) on various SCN4A dinucleotide repeat haplotypes and therefore the majority of the mutations probably occurred independently. However, the R1448H mutation is extremely frequent in the North-West of Germany (Ravensberger Land) on a specific SCN4A microsatellite haplotype, indicating a founder effect within this subpopulation. Our results suggest that the R1448C/R1448H mutations are by far the most common to be associated with the PC phenotype in the German population.This paper is dedicated to Professor Dr. Dr. Peter Emil Becker on the occasion of this 85th birthday     

Heterogeneity of soil and soil solution chemistry under Norway spruce (Picea abies Karst.) and European beech (Fagus silvatica L.) as influenced by distance from the stem basis

The present study aims at characterizing plant water status under field conditions on a daily basis, in order to improve operational predictions of plant water stress. Ohm's law analog serves as a basis for establishing daily soil-plant relationships, using experimental data from a water-limited soybean crop: 227-1. The daily transpiration flux, T, is estimated from experimental evapotranspiration data and simulated soil evaporation values. The difference, 227-2, named the effective potential gradient, is derived from i) the midday leaf potential of the uppermost expanded leaves and ii) an effective soil potential accounting for soil potential profile and an effectiveness factor of roots competing for water uptake. This factor is experimentally estimated from field observation of roots. G is an apparent hydraulic conductance of water flow from the soil to the leaves. The value of the lower potential limit for water extraction, required to assess the effective soil potential, is calculated with respect to the plant using the predawn leaf potential. It is found to be equal to –1.2 MPa. It appears that over the range of soil and climatic conditions experienced, the daily effective potential gradient remains constant (1.2 MPa), implying that, on a daily basis, transpiration only depends on the hydraulic conductance. The authors explain this behaviour by diurnal variation of osmotic potential, relying on Morgan's theory (1984). Possible generalization of the results to other crop species is suggested, providing a framework for reasoning plant water behaviour at a daily time step.     

The effect of water flow on photosynthetic processes of the alga Ulva lactuca L.

Photosynthetic rates of aquatic macrophytes are affected by the diffusion of carbon through the boundary layer which decreases with increasing flow velocities. This is shown by a significant increase in photosynthetic rates of Ulva lactuca fronds exposed to friction velocities (u _*) between 0.0 and 0.3 cm s^–1. No further increase in photosynthetic rates is observed at u _* values between 0.3 and 1.0 cm s^–1. Stagnating flow conditions at saturating light levels caused a 29% reduction in photosynthetic rates. Experiments in a closed system indicate that Ulva may utilize internal carbon sources during periods of stagnation. On a subtidal rock directly exposed to wave action, Ulva lactuca is not exposed to such conditions while in a wave flushed intertidal pool stagnation occurs during very short time intervals based on in situ measurements of u _* levels on fronds of this species using a microprocessor-controlled, autonomous recorder and hot-film sensors.     

Differences in erythropoiesis in normal chicken and quail embryos

Summary Using antibodies against the fetal and adult forms of - and -globin, it has been shown that erythropoiesis in the para-aortic foci (PAF) constitutes a major species-specific difference between chicken and quail embryos. In quail embryos, para-aortic foci are rare, small and rather heterogeneous with regard to their erythropoietic and haemopoietic cell composition. In contrast, the PAFs in chicken embryos are abundant and consist of large numbers of erythropoietic cells.In both species a time difference (approximately 1 day) is observed between the first expression of the fetal - and -globin and the adult - and -globin in erythropoietic cells. Adult erythropoiesis in both species can be detected first in the stalk of the yolk sac; this is similar to the situation in mammalian and amphibian species. From this time onward the number of circulating adult erythrocytes increases steadily. Whereas in chicken, large intraembryonic foci that can serve as sources for these adult cells arise concomitantly, no such foci can be detected in quail embryos, suggesting that the quail yolk sac is a major source for these adult red blood cells.     

Zur Frage des Einflusses von Spurenelementen auf Bacillus asterosporus

Zusammenfassung Der Einfluß des Kobalts im Kohlenhydratstoffwechsel von Bac. asterosporus wird untersucht. Bei der optimalen Konzentration von 4 Co/ml wird die Kohlensäurebildung bei den untersuchten Kohlenstoffquellen Dextrose, Saccharose, Fructose und Mannit durchschnittlich um 80% reduziert. Der ökonomische Koeffizient erfährt bei Dextrose eine Erhöhung um 100%, bei Saccharose um 30%, der Atmungskoeffizient bei allen vier Kohlenstoffquellen eine Erniedrigung von 55–89%. Ascorbinsäure zeigt die gleiche Reduktion der Kohlensäurebildung wie Kobalt, während Aneurin darauf keine Wirkung ausübt. Der r_H-Wert wird durch Kobalt vermindert. Aus den Ergebnissen wird im Zusammenhang mit anderen Arbeiten geschlossen, daß der Stoffwechsel des fakultativ anaeroben Bac. asterosporus durch Kobalt mehr zur anaeroben Seite hin und zu homolaktischer Gärung verschoben wird. Die Untersuchungen zur Aufklärung des Wirkungsmechanismus von Kobalt werden fortgesetzt.Teilweise vorgetragen am 20. September 1954 anläßlich der österreichischen Mikrobiologentagung in Innsbruck (Dedic 1955).     

The Na+,K+,2Cl−-cotransport system in HeLa cells: Aspects of its physiological regulation

We have previously reported on the biochemical properties of a Na⁺,K⁺,2Cl^?-cotransport in HeLa cells and here we deal with aspects of its physiological regulation. Na⁺,K⁺,2Cl^?-cotransport in HeLa cells was studied by ⁸⁶Rb⁺ influx and ⁸⁶Rb⁺/²²Na⁺ efflux measurements. The effects of rat atrial natriuretic peptide (ANP), isoproterenol, and amino acids on ⁸⁶Rb⁺ flux, mediated by the bumet-anide-sensitive Na⁺, K⁺, 2Cl^?-cotransport system and the ouabain-sensitive Na⁺/K⁺-pump, were investigated. ANP reduced bumetanide-sensitive ⁸⁶Rb⁺ influx under isotonic as well as under hypertonic conditions. Similar decrease of bumetanide-sensitive ⁸⁶Rb⁺ influx was observed in the presence of 8-bromo-cGMP, while neither isoproterenol as a β-receptor agonist nor 8-bromo-cAMP-could alter bumetanide-sensitive ⁸⁶Rb⁺ influx. Furthermore, efflux of ⁸⁶Rb⁺ and ²²Na⁺ was greatly reduced in the presence of bumetanide and ANP. Together with our recent findings, showing functionally active, high affinity receptors for ANP on HeLa cells (Kort and Koch, Biochim. Biophys. Res. Commun. 168:148–154, 1990), this study indicates that ANP participates in the regulation of the Na⁺, K⁺, 2Cl^?-cotransport system in HeLa cells. Further measurements revealed that amino acids as present in the growth medium (Joklik's minimal essential medium) and the amino acid derivative α-methyl-aminoisobutyric acid (metAlB, 1 and 5 mM, respectively) also reduced Na⁺, K⁺, 2Cl^?-cotransport-mediated ⁸⁶Rb⁺ uptake and diminished the stimulatory effect of hypertonicity on the cotransporter. In addition, the Na⁺/K⁺-pump was markedly stimulated in the presence of amino acids, while neither ANP and 8-Br-cGMP nor isoproterenol and 8-Br-cAMP had a significant effect on the activity of the Na⁺/K⁺-pump.     

Yeast glycogenin (Glg2p) produced in Escherichia coli is simultaneously glucosylated at two vicinal tyrosine residues but results in a reduced bacterial glycogen accumulation.

Saccharomyces cerevisiae possesses two glycogenin isoforms (designated as Glg1p and Glg2p) that both contain a conserved tyrosine residue, Tyr232. However, Glg2p possesses an additional tyrosine residue, Tyr230 and therefore two potential autoglucosylation sites. Glucosylation of Glg2p was studied using both matrix-assisted laser desorption ionization and electrospray quadrupole time of flight mass spectrometry. Glg2p, carrying a C-terminal (His6) tag, was produced in Escherichia coli and purified. By tryptic digestion and reversed phase chromatography a peptide (residues 219-246 of the complete Glg2p sequence) was isolated that contained 4-25 glucosyl residues. Following incubation of Glg2p with UDPglucose, more than 36 glucosyl residues were covalently bound to this peptide. Using a combination of cyanogen bromide cleavage of the protein backbone, enzymatic hydrolysis of glycosidic bonds and reversed phase chromatography, mono- and diglucosylated peptides having the sequence PNYGYQSSPAM were generated. MS/MS spectra revealed that glucosyl residues were attached to both Tyr232 and Tyr230 within the same peptide. The formation of the highly glucosylated eukaryotic Glg2p did not favour the bacterial glycogen accumulation. Under various experimental conditions Glg2p-producing cells accumulated approximately 30% less glycogen than a control transformed with a Glg2p lacking plasmid. The size distribution of the glycogen and extractable activities of several glycogen-related enzymes were essentially unchanged. As revealed by high performance anion exchange chromatography, the intracellular maltooligosaccharide pattern of the bacterial cells expressing the functional eukaryotic transgene was significantly altered. Thus, the eukaryotic glycogenin appears to be incompatible with the bacterial initiation of glycogen biosynthesis.