Kongreßbericht

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Der Gegner beim Vertragsabschluß und im Prozeß

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Cactaceen-Virus-Eiweißspindeln

Zusammenfassung Rhipsalis cereuscula enthält, wenn sie aufPereskia aculeata gepfropft ist, hauptsächlich, in der Epidermis und Subepidermis der Sprosse zahlreiche große Eiweißgebilde verschiedener Gestalt. Diese Gebilde werden als Viruskörper gedeutet. Die Eiweißspindeln lassen bisweilen einen zopfartigen Aufbau aus einer Anzahl von einzelnen Strängen erkennen. In manchen Zellen sieht man x-body-artige Plasmakugeln, mit denen die Virus-Eiweißkörper bisweilen in Kontakt stehen.Hans Fitting zum 75. Geburtstag gewidmet.     

Einfluß von außenfaktoren auf den fortpflanzungsmodus heterogoner rotatorien

Summary Monogonont rotifers reproduce parthenogenetically or sexually. The proportion of sexual females in a population (rate of mixis) can be modified by external factors. Published data about these factors are inconsistent and in part even contradictory (Table 1).In summer 1967 we made quantitative plankton studies in 15 tanks (0.3 to 50 m³). The following parameters were recorded every third day: population density, egg rate (eggs/female), and rate of mixis of the three rotifer species Brachionus calyciflorus, B. rubens and B. angularis; pH, temperature, rainfall, and phytoplankton biomass (dry weight). The latter was subdivided into three categories: ultra, nanno and micro-plankton.A correlation analysis of the environmental factors revealed many intercorrelations (Table 2). The coefficients of correlation between each rate of mixis and all other parameters are given in Table 3. A most striking result is the absence of significant correlations among the rates of mixis of the three species. This means that the periods of sexuality of the three related species are independent of one another in the same biotope. No one factor shows a consistent positive or negative correlation with the rates of mixis of all three species. But there are no contradictions, i.e., none of the parameters is correlated positively in one species and negatively in another species. Positive correlations (or none) are demonstrated with temperature, changing of temperature, and micro-phytoplankton; negative correlations (or none) with total phytoplankton, ultra-phytoplankton, nanno-phytoplankton, eggs/female, and population density of the competing Brachionus species; in no case are significant correlations found with pH and rainfall. That factors with significant correlations do not show these correlations with all species could be due to different threshold values of the mixis-inducing factors in the three rotifer species.In one respect our analysis is at variance with previous findings: whereas in all published data the population growth rate promotes the rate of mixis, we find in no case a significantly positive correlation between the rate of mixis and the population growth rate, or the rate of eggs/female. In some cases we find a significantly negative correlation.At present it is difficult to decide, whether the significant factors influence the rate of mixis directly or indirectly. The intercorrelations of the factors (Table 2) suggest that in many if not most cases these influences are indirect. tionsdichte von B. calyciflorus (bei B. rubens). Der letzte Effekt ist wahrscheinlich auf Konkurrenz zurückzuführen (Halbach, in Vorbereitung).

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Herrn Prof. Dr. H.-J. Autrum in Verehrung und Dankbarkeit zum 65. Geburtstag gewidmet.     

Über den Einfluß von Außenbedingungen auf die Chromosomenreduktion

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Eiweißkristalloide vonLilium tigrinum

Zusammenfassung In den Epidermiszellen der Zwiebelschuppe vonLilium tigrinum treten verschieden geformte Proteinkristalloide auf. Besonders merkwürdig sind die Zebraspindeln, die in ihrer Struktur vollkommen denen gleichen, die in Kakteen gefunden wurden; sie werden für Virusträger gehalten.     

ß-Alanine and ß-Aminoisobutyric Acid Levels in Two Siblings With Dihydropyrimidinase Deficiency

Dihydropyrimidinase (DHP) deficiency is an inborn error of the pyrimidine degradation pathway, affecting the hydrolytic ring opening of the dihydropyrimidines. In two siblings with a complete DHP deficiency and a variable clinical presentation, a normal concentration of ß-alanine and strongly decreased levels of ß-aminoisobutyric acid were observed in plasma, urine and CSF. No major differences were observed for the concentrations of the ß-amino acids in plasma and urine between the symptomatic and asymptomatic sibling. Thus, the relevance of the shortage of ß-aminoisobutyric acid for the onset of a clinical phenotype in patients with DHP deficiency remains to be established.