SARCOCYSTIS MURIS BLANCHARD BEI EINER MICROTUSART

Aus dem umfangreichen Material der oben angef(?)hrten Sammelreise erhielt ich von Herrn Dr. R. Piechocki eine in einer Schlagfalle gefangene, bereits entpelzte Microtusart. Die Bestimmung ergab Microtus maximowiczii Schrenk. Pr(?)ft man die Literatur (?)ber Sarcosporidienbefall nach, so findet man bis     

Effect of retinoic acid on the proliferation and tumorigenicity of mouse mastocytoma cells

Retinoic acid (RA) inhibited the in vitro growth of the mouse mast cell tumor line P₈₁₅ in a dose- and time-dependent manner. The inhibition was accompanied by an increase in the amount of neutral intracellular mucopolysaccharides. Study of cell cycle kinetics showed that exposure to retinoic acid led to a slowing-down of the cell-cycle progression possibly related to a more differentiated cell population disclosed by microscopy with a lower proliferative capacity. In vivo, delays in both tumor appearance and mouse mortality were observed after injecting RA into mice bearing mastocytomas. These results suggest that RA could be of interest in the treatment of human malignant systemic mastocytosis with proliferation of immature mast cells.     

Diurnal Rhythmicity in the Pattern of mRNAs in the Leaves of Sinapis alba

Previous studies have shown that certain specific leaf mRNAs exhibit a diurnal rhythmicity in their quantity in higher plants. To determine whether this situation is restricted to a few mRNAs, or affects a large number, we have used in vitro translation and two-dimensional polyacrylamide gel electrophoresis to analyze the mRNA complement in leaves of Sinapis alba at different times during an 8-hour/16-hour day/night cycle. A method for the visual analysis of two-dimensional polyacrylamide gel electrophoresis was also developed. This method selected, at each sampling time, spots that were significant. It then selected, between two sampling times, intensity changes that were significant at the 0.02 confidence level. During a day/night cycle, complex rhythmic changes affected about 10% of the mRNAs. Nineteen different rhythm patterns were found. These 19 patterns fell into four main classes: mRNAs that increase during the light period and decrease during the dark, mRNAs that increase and then decrease during the light period, mRNAs that decrease during the light period and increase during the dark period, and mRNAs that increase and then decrease during the dark period.     

The excess of transitions among nucleotide substitutions: new methods of estimating transition bias underscore its significance

Estimates of transition bias provide insight into the process of nucleotide substitution, and are required in some commonly used phylogenetic methods. Transitions are favored over transversions among spontaneous mutations, and the direction and strength of selection on proteins and RNA appears to depend on mutation type. As the complexity of the nucleotide-substitution process has become apparent, problems with classical methods of estimating transition bias have been recognized. These problems arise because there Is a fundamental difference between ratios of numbers of differences among sequences and ratios of rates, and because classical methods are not easily generalized. Several new methods are now available.