TITLE:
Experimental Induction of Heterotrophic to Autotrophic Conversion, Realized by the Enforced Primary Endosymbiosis of Photosynthetic Bacteria onto Eukaryotic Amoebae
AUTHORS:
Yasuo Maeda, Tomoaki Abe
KEYWORDS:
Evolution, Multinucleate Plasmodium, Dictyostelium, Rhodobacter, Synechocystis
JOURNAL NAME:
Natural Science,
Vol.14 No.9,
September
29,
2022
ABSTRACT: 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.