caa a22 4500 465744907 CHVBK 20180323111818.0 cr unu---uuuuu 170327e19901101xx s 000 0 eng 10.1007/BF01808197 doi (NATIONALLICENCE)springer-10.1007/BF01808197 Cellular differentiation in the process of generation of the eukaryotic cell [Elektronische Daten] [Hakobu Nakamura, Atsushi Hase] Primitive atmosphere of the earth did not contain oxygen gas (O2) when the proto-cells were generated successfully as the resut of chemical evolution and then evolved. Therefore, they first had acquired anaerobic energy metabolism, fermentation. The cellular metabolisms have often been formed by reorganizing to combine or recombinate between pre-existing metabolisms and newly born bioreactions. Photosynthetic metabolism in eukaryotic chloroplast consists of an electron-transfer photosystem and a fermentative reductive pentose phosphate cycle. On the other hand, O2-respiration of eukaryotic mitochondrion is made of Embden-Meyerhof (EM) pathway and tricarboxylic acid cycle, which originate from a connection of fermentative metabolisms, and an electron-transfer respiratory chain, which has been derived from the photosystem. These metabolisms already are completed in some evolved prokaryotes, for example the cyanobacteriumChlorogloea fritschii and aerobic photosynthetic bacteriaRhodospirillum rubrum andErythrobacter sp. Therefore, it can be reasonably presumed that the eukaryotic chloroplast and mitochondrion have once been formed as the result of metabolic (and genetic) differentiations in most evolved cyanobacterium. Symbiotic theory has explained the origin of eukaryotic cell as that in which the mitochondrion and chloroplast have been derived from endosymbionts of aerobic bacterium and cyanobacterium, respectively, and has mentioned as one of the most potent supportive evidences that amino acid sequences of the photosynthetic and O2 -respiratory enzymes show similarities to corresponding prokaryotic enzymes. However, as will be shown in this discussion, many examples have shown currently that prokaryotic sequences of informative molecules are conserved well not only in those of the mitochondrial and chloroplast molecules but also in the nuclear molecules. In fact, the similarities in sequence of informative molecules are preserved well among the organisms not only in phylogenetically close relationships but also under highly selective pressure, that is under a physiological constraint for the species in their habitats. Therefore, the similarities in amino acid sequences of proteins between the prokaryotes and the organelles are not necessarily direct evidence for their phylogenetical closeness: it gives still less evidence for a symbiotic relationship between the prokaryotes and the organelles. The metabolic compartmentalization of the membranes is an important tendency in cellular evolution to guarantee high specificity and rate of the metabolisms. It is suggested from the data that the intracellular membranes are not static but undergo dynamic turnover. Furthermore, these facts strongly support the Membrane Evolution Theory which was proposed by one of the authors in 1975. Kluwer Academic Publishers, 1990 Nakamura Hakobu Biological Institute, Faculty of Science Konan University, 658, Kobe, Japan aut Hase Atsushi Osaka City Institute of Public Health and Environmental Sciences, 543, Osaka, Japan aut Origins of life and evolution of the biosphere Kluwer Academic Publishers 20/6(1990-11-01), 499-514 0169-6149 20:6<499 1990 20 11084 https://doi.org/10.1007/BF01808197 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01808197 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Nakamura Hakobu Biological Institute, Faculty of Science Konan University, 658, Kobe, Japan aut NATIONALLICENCE 700 1- Hase Atsushi Osaka City Institute of Public Health and Environmental Sciences, 543, Osaka, Japan aut NATIONALLICENCE 773 0- Origins of life and evolution of the biosphere Kluwer Academic Publishers 20/6(1990-11-01), 499-514 0169-6149 20:6<499 1990 20 11084 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer