Ból i cierpienie

Praca recenzowana / peer-reviewed pape

Evolution of major changes in animal morphology. Remarks on evolution of animal developmental program and on human genetic heritage

Evolution of complex organisms required additions of new gene loci and appearing of new functions by duplications of preexisting genes and subsequent diversification of duplicated copies. However, the number of genes in genome is surprisingly low in animal and human genomes, since it is limited by genetic load, which is a function of mutation rate and real number of genes,. The genetic information of a higher organism is organized in a very economical way. There is hierarchical regulation of genes transcription by transcription factors, and pathways of post translational regulation of activity of gene products that are common for the whole animal kingdom. The roles of hox genes, wnt/catenin and apoptosis pathways in animal development, evolution, and homology of genes involved in these regulations (ortolologous and paralogous) are discussed in this article. It may be speculated that a common ancestor of all animals contained a set of genes of developmental program which was prerequisite for animal evolution. There is some difficulty in explanation how extensive morphological changes could be favoured by natural selection. The problem of "macroevolution" may be reduced to evolution of developmental program. However, this evolution did not require special mechanisms not consistent with paradigms of the theory of evolution

Effects of Roscovitine on Schedule of Divisional Morphogenesis, Basal Bodies Proliferation and Cell Divisions in Tetrahymena thermophila

Summary. During cell cycle of a ciliate Tetrahymena thermophila the divisions of micro- and macronucleus, cortical morphogenesis and ' cytokinesis are temporarily coordinated. Cortical morphogenesis begins with proliferation of the new ciliary basal bodies (BBs) within meridional cortical rows of ciliary BBs, and with the local proliferation of BBs, which form the new oral apparatus (OA2), positioned subequatorialy and destined for prospective posterior daughter cell (opisthe). Prior to cytokinesis, two prospective daughter cells are of equal size and show metamery of their cortical patterns. We studied effects of 20 uM roscovitine (an inhibitor of several cyclin-dependent kinases) on the cell cycle progression of T. thermophila. We showed that roscovitine delayed cell division, delayed or arrested macronuclear division and induced increase of cell size and the number of BBs in the cortical rows. The increase in the number of BBs in cortical rows induced cell elongation which was proportional to the increase in cell surface area. There was uncoupling between this BBs_proliferation which is continued during prolonged cell cycle and delayed cytokinesis, what resulted in topological alteration of the respective positions of the OA2 and of the contractile vacuole pores (CVPs). In roscovitine treated cells, the new OA2 was positioned subequatorialy, but the fission zone was shifted posterior to the equatorial plane of the cell and positioned across and in the extreme cases behind of the new OA2. This resulted in the formation of a large proter and small size opisthe. The roscovitine treatment induced a formation of a plethora of phenotypes of postdividing cells. We found that irrespective of changes in divisional morphogenesis induced by roscovitine treatment, all mature BBs were associated with the cdc!4-like phosphatase. Taken together all these data indicate that during cell cycle of T. thermophila the normal morphology of the daughter cells depends on the proper division of micro- and macronucleus and on temporal control of BBs proliferation along the longitudinal rows, during OA2 stomatogenesis and during selection of BBs involved in differentiation of apical BBs (couplets) and cell division. Key words: Tetrahymena, roscovitine, basal bodies, morphogenesis, macronucleus, cdc!4p. Addres

Effects of Roscovitine on Schedule of Divisional Morphogenesis, Basal Bodies Proliferation and Cell Divisions in Tetrahymena thermophila

During cell cycle of a ciliate Tetrahymena thermophila the divisions of micro- and macronucleus, cortical morphogenesis and cytokinesis are temporarily coordinated. Cortical morphogenesis begins with proliferation of the new ciliary basal bodies (BBs) within meridional cortical rows of ciliary BBs, and with the local proliferation of BBs, which form the new oral apparatus (OA2), positioned subequatorialy and destined for prospective posterior daughter cell (opisthe). Prior to cytokinesis, two prospective daughter cells are of equal size and show metamery of their cortical patterns. We studied effects of 20 μM roscovitine (an inhibitor of several cyclin-dependent kinases) on the cell cycle progression of T. thermophila. We showed that roscovitine delayed cell division, delayed or arrested macronuclear division and induced increase of cell size and the number of BBs in the cortical rows. The increase in the number of BBs in cortical rows induced cell elongation which was proportional to the increase in cell surface area. There was uncoupling between this BBs proliferation which is continued during prolonged cell cycle and delayed cytokinesis, what resulted in topological alteration of the respective positions of the OA2 and of the contractile vacuole pores (CVPs). In roscovitine treated cells, the new OA2 was positioned subequatorialy, but the fission zone was shifted posterior to the equatorial plane of the cell and positioned across and in the extreme cases behind of the new OA2. This resulted in the formation of a large proter and small size opisthe. The roscovitine treatment induced a formation of a plethora of phenotypes of postdividing cells. We found that irrespective of changes in divisional morphogenesis induced by roscovitine treatment, all mature BBs were associated with the cdc14-like phosphatase. Taken together all these data indicate that during cell cycle of T. thermophila the normal morphology of the daughter cells depends on the proper division of micro- and macronucleus and on temporal control of BBs proliferation along the longitudinal rows, during OA2 stomatogenesis and during selection of BBs involved in differentiation of apical BBs (couplets) and cell division