Genetic and epigenetic factors affecting meiosis induction in eukaryotes revealed in paramecium research.
This review presents studies of the induction of meiosis undertaken on the ciliate Paramecium, a unicellular model eukaryotic organism. Meiosis in Paramecium, preceding the process of fertilization, appears in starved cells after passing a defined number of divisions (cell generations), starting from the last fertilization. Investigations were performed on clones of cells entering autogamy, a self-fertilization process. Genetic as well as epigenetic factors, i.e. endo- and exogenous factors, affecting the induction ofmeiosis and changing the duration of the interautogamous interval (IAI), were analyzed. The results show that: (1) Meiosis induction is controlled genetically by the somatic macronucleus. However, besides the nuclear factors, the cytoplasmic protein immaturin also affects this process (Haga & Hiwatashi 1981); (2) Epigenetic factors, such as non-genetically disturbed cytoskeleton structures and changes in the cell architecture observed in doublet Paramecium cells, exert internal mechanical stress (Ingber 2003), which constitutes the endogenous impulse accelerating meiosis; (3) Mild osmotic stress, acting as an exogenous factor, can initiate the specific MAP kinases signaling pathway resulting in earlier meiosis induction, as in other unicellular eukaryotes (Seet & Pawson 2004).
Prajer
Małgorzata
M
Department of Experimental Zoology, Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Slawkowska 17, 31-016 Kraków, Poland. prajer@isez.pan.krakow.pl
D000818:Animals; D044127:Epigenesis, Genetic; D005306:Fertilization / Q000502:physiology; D020935:MAP Kinase Signaling System / Q000502:physiology*; D048648:Macronucleus / Q000502:physiology*; D008540:Meiosis / Q000235:genetics*; D009997:Osmotic Pressure; D010247:Paramecium / Q000235:genetics / Q000502:physiology*; D015800:Protozoan Proteins / Q000378:metabolism
D015800:Protozoan Proteins; C045409:immaturin protein, Paramecium caudatum