Killer toxin producing strains of the yeasts Hanseniaspora uvarum and Pichia kluyveri

By heat treatment killer strains of the type K1 of Saccharomyces cerevisiae that are known to harbour dsRNA plasmids were completely cured, whereas only a small fraction of the clones of the killer type K2 had lost the dsRNA dependent killer character. The K2 killers but not the strains of killer type K1 were easily cured by cycloheximide. Killer strains of Hanseniaspora uvarum were not curable by heat treatment. Curing was successfull with cycloheximide or 5-fluorouracil. Two double-stranded RNA plasmids were detected in the killer strains of H. uvarum. The smaller dsRNA plasmid was absent in the strains that were cured of their killer character by 5-fluorouracil. The killer character of H. uvarum was transferred to S. cerevisiae by spheroplast fusion. The fusion products showing the killer character contained both dsRNA plasmids, obviously the smaller plasmid (M-dsRNA) carries the genes for killer toxin formation. Killer strains of Pichia kluyveri were not curable of their killer character, in these strains no dsRNA plasmids were detected.This paper was kindly supported by a grant from the Deutsche Forschungsgemeinschaft     

Does a-linolenic acid in combination with linoleic acid influence liver metastasis and hepatic lipid peroxidation in BOP-induced pancreatic cancer in Syrian hamsters?

Some fatty acids are reported to inhibit tumor growth of pancreatic carcinoma. However, it is still unknown if α-linolenic acid (ALA) and linoleic acid (LA) inhibit liver metastasis of ductal pancreatic adenocarcinoma. Therefore we studied the effect of these fatty acids on liver metastasis in the animal model of N-nitrosobis(2-oxopropyl)amine (BOP)-induced pancreatic adenocarcinoma in Syrian hamsters. Since lipid peroxidation seems to be involved in carcinogenesis and metastasis, we further analyzed the intrahepatic concentration of thiobarbituric acid-reactive substances (TBARS) and activity of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD).We observed an increase in the incidence and the number of liver metastase in response to the combination of ALA and LA. This was accompanied by a decrease in hepatic GSH-Px activity and an increase in hepatic SOD activity and TBARS concentration. The increase in hepatic lipid peroxidation seems to be one possible mechanism of increasing liver metastasis in this study.     

The effect of mixtures of acetic acid and D-xylose on the growth rate of Candida blankii

Summary The growth rate of the yeastCandida blankii in carbon-limited chemostat culture on a mixture of D-xylose and acetic acid as carbon sources was determined not only by the acetic acid concentration in the feed, but also by the ratio of xylose to acetic acid. The hypothesis is put forward that the inhibitory effect of acetic acid on the growth rate is determined, in part, by the specific rate of acetic acid metabolism.     

Tissue-Autonomous Phenylpropanoid Production Is Essential for Establishment of Root Barriers

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