ABSTRACT
Spiropyran-containing methanofullerenes able to rapidly and reversibly respond to optical and chemical stimuli were synthesized for the first time by the Bingel-Hirsch reaction and catalytic cycloaddition of diazo compounds to carbon clusters. The effects of substituent structure in the new hybrid molecule and the mode of spiropyran attachment to fullerene on the spectral kinetic properties and photo- and acidochromic behavior of the synthesized fullerene derivatives was established.
ABSTRACT
Silver staining of the nucleoli in pig embryo kidney cells (PK) was studied during the cell cycle and also upon mature nucleoli modifications induced by UV microirradiation. During anaphase only four silver-stained granules were revealed in each daughter set of chromosomes in the four nucleolus-organizing regions (NORs). In the following 1-2 hours, the number of granules in the NORs rapidly increased up to 25-30 per nucleus. During the next 20-25 hours of the cell cycle, the number of silver-stained granules was slowly doubling as the nucleoli grew in size. UV microirradiation of one nucleolus in the nucleus with two nucleoli induced a profound degradation of the injured nucleolus and a compensatory hypertrophy of the intact one. Such nucleolar modifications were accompanied by redistribution of the silver-stained granules between the injured and non-injured nucleoli and by alterations in the levels of nucleolar RNA synthesis in the NORs. These data support a hypothesis that silver-stained proteins may be involved in the regulation of the nucleolar activity.
Subject(s)
Cell Nucleolus/radiation effects , Kidney/radiation effects , RNA/radiation effects , Ultraviolet Rays , Animals , Autoradiography , Cell Cycle/radiation effects , Cell Line , Cell Nucleolus/metabolism , Cells, Cultured , Kidney/ultrastructure , Nucleolus Organizer Region/metabolism , Nucleolus Organizer Region/radiation effects , RNA/biosynthesis , Silver Nitrate , Staining and Labeling/methods , Swine , TritiumABSTRACT
Dependence of changes in the intracellular free iron content upon cellular proliferation has been studied on mammalian cells in vitro. It has been established that picolic acid (PA)--a natural metal chelating agent of variable valency--inhibits the proliferation of cultivated pig embryo kidney cells (SPEV). Simultaneously the free iron quantity was decreased 2-fold as compared with the norm. PA block was removed by substituting PA-containing cultivated media for the PA-free one. It was accompanied by complete recovery of the free iron quantity in the cells. The regulation of cell proliferation is likely to correlate with the intracellular free iron content.
