dictyNews
Electronic Edition
Volume 48, number 18
September 2, 2022

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Abstracts
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Experimental induction of heterotrophic to autotrophic conversion, 
realized by the enforced primary endosymbiosis of photosynthetic 
bacteria onto eukaryotic amoebae

Yasuo Maeda1*and Tomoaki Abe2 

1.Department of Developmental Biology and Neurosciences, Graduate 
School of Life Sciences, Tohoku University, Aoba, Sendai 980-8578, 
Japan. 
2.Institute of Biological Sciences, Faculty of Science and 
Engineering, Ishinomaki Senshu University, Ishinomaki 986-8580, 
Japan.

*Correspondence:
Yasuo Maeda, Department of Developmental Biology and Neurosciences, 
Graduate School of Life Sciences, Tohoku University, Aoba, Sendai 
980-8578, Japan. 
E-Mail: [log in to unmask]


Natural Science, in press

The primary endosymbiosis of cyanobacteria with primitive eukaryotes 
is assumed to have occurred in ancient times, leading to the 
formation of plants with chloroplasts. However, since this possibility 
has remained experimentally unproven, we tried to convert heterotrophic 
eukaryotes like protozoa to autotrophs with chloroplasts. For this, 
when eukaryotic and heterotrophic Dictyostelium cells were forcibly 
cultivated with two kinds of photosynthetic bacteria (the purple non-
sulfur bacterium Rhodobacter and then the cyanobacterium Synechocystis) 
as food sources, unique autotrophic organisms consisting of 
multinucleate plasmodia and their derived amoeboid cells, which had 
very strange morphology and behaviors, were formed by endosymbiosis 
of the bacteria. In this case, long-term pre-cultivation with Rdodobacter 
seemed to be prerequisites for the formation of the autotrophic 
organisms. The resulting, green-colored plasmodium contained a number 
of Synechocystis-derived bodies in the cytoplasm. The measurement of 
chlorophyll fluorescence indicates that the Synechocystis-derived 
bodies are like chloroplasts giving the ability of photosynthesis. 
Only, since the fine structural characteristics and genetic background 
of the autotrophic multinucleate plasmodia and their derived- amoeboid 
cells are extremely strange, we discuss the possibility of thinking 
about those reasons. 

Keywords
evolution, multinucleate plasmodium, Dictyostelium, Rhodobacter, 
Synechocystis


Submitted by Yasuo Maeda [[log in to unmask]]
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[End dictyNews, volume 48, number 18]