[Intracellular pool of free amino acids in dehydrated yeast organisms]. / Issledovanie sostoianiia vnutrikletochnogo pula svobodnykh aminokislot pri obezvozhivanii drozhzhevykh organizmov.

The dehydration of Saccharomyces cerevisiae was found to result in a noticeable decrease of the free amino acids content in the cells and in a considerable increase of cytoplasmic membrane permeability for these compounds. When the dehydrated organisms were reactivated, the normal permeability of the cytoplasmic membrane gradually restored and the pool of free amino acids increased in the cells.

[Resistance of mesospheric microorganisms to periodic freezing--thawing]. / Ustoichivost' mikroorganizmov mezosfery k periodicheskomu zamorazhivaniiu-ottaivaniiu.

The object of this work was to study cytological changes caused by periodic freezing-thawing in the conidia of the fungi Aspergillus niger and Penicillium chrysogenum isolated from the mesosphere as well as in the conidia of the same species taken from the collection of microorganisms. The conidia from the mesosphere were found to be highly resistant to the treatment. As was shown by electron microscopy, the outer "backbone" layer of the spore envelope broke down and the membranes of the plasmalemma stratified after ten cycles in A. niger and P. chrysogenum. The percentage of conidia with the damaged ultrastructural organization was higher in mutants of these cultures.

[Formation and degradation of peroxisomes in yeasts]. / O vozniknovenii i degradatsii peroksisom u drozhzhevykh organizmov.

The formation, development and degradation of peroxisomes were studied directly in growing yeast-methylotrophs under the microscope using anoptral and phase contrast. The degradation of peroxisomes was caused by their degeneration and dislocation to the central vacuole of the yeast cell. A fluorescent-microscopic technique was elaborated for detecting selectively the crystals of catalase in the cells. As was shown by intravitam studies, electron microscopy and cytochemistry, peroxisomes are directly connected with the central vacuole of the cell, enzymes being transferred from the former into the latter. Experiments conducted with different cultures have demonstrated that the high activity of exocatalase is typical of methylotrophic yeast organisms. The highest activity that was exhibited for a long period of time was found in Torulopsis molischiana.

[Yeast peroxisomes, their development and operation]. / Peroksisomy drozhzhevykh organizomv, ikh razvitie i funktsionirovanie.

Yeast peroxisomes (microbodies) were studied, particularly with yeast methylotrophs, using light-optical microscopy, viz. intravitam phase- and anoptral-contrast microscopy, with cytochemical as well as fixed and stained objects. The data obtained were compared with cytochemical as well as fixed and stained objects. The data obtained were compared with other evidence that we had gained on methylotrophs studied by electron microscopy and with the results obtained by investigating the peroxisomes of yeast cultures grown on nutrient containing other carbon sources. The activity of exocatalase and endocatalase, the enzymes characteristic of peroxisomes, was assayed at different growth phases of yeast methylotrophs and was found to be correlated with the cycle of development of peroxisomes. The content of biotin and inositol and its dynamics were studied in the methylotroph cells. Possible origin of peroxisomes is discussed as well as their development and the mechanism of degradation. A close contact and functional relationship have been established between peroxisomes and mitochondria.