The evolution of symbiotic systems


Symbiosis refers to close and sympatric interactions between species. The interactions involve dynamic changes of genomes, metabolisms, and signaling networks of symbiotic partners. A unified understanding of these interactions is required when studying symbiotic organisms. To emphasize the enormous variety of symbiotic consortia and the underlying commonalities that relate these systems, James Lake and I organized the 7th Okazaki Biology Conference (OBC) on ‘‘The Evolution of Symbiotic Systems,’’ hosted by the National Institute for Basic Biology, from January 11–14, 2010, in Kakegawa, Japan. The OBC is an international conference dedicated to providing opportunities to create new networks of scientists and to facilitate the development of future areas of fundamental research in the biological sciences. The topics ranged broadly and included early prokaryotic endosymbiosis, the evolution of plastids, diversity of endosymbionts, partner shifts, interdependent genomes, marine symbioses, insect–microbe interactions, plant– microbe interactions, and artificial symbiotic systems. Of these various symbioses ranging from intracellular to interspecific, six topics are introduced in this multi-author review. Apicomplexans are a group of protists that are obligate intracellular parasites in animals including humans. With some exceptions, apicomplexans have a tiny plastid-like organelle called an apicoplast that is thought to have originated from secondary endosymbiosis of a red algae [1]. The apicoplast of parasitic apicomplexans such as the human malaria Plasmodium falciparum is nonphotosynthetic but has become indispensable because it functions in other metabolisms supplying essential products to the host. In contrast to the metabolisms involving the apicoplast, housekeeping functions of the organelles have remained unclear, though they are often unique or differ markedly from those of other organisms. Sato sheds light on the apicoplast and its uniqueness in the housekeeping functions. Aphids are small, soft-bodied insects and feed exclusively on plant phloem sap. They have been associated with intracellular symbiotic bacteria that synthesize essential amino acids. In the case of the pea aphid, its symbiotic bacteria Buchnera aphidicola are absolutely required for host growth and reproduction. These bacteria are transmitted from mother to offspring through host generations. In 2000, Shigenobu and associates reported the complete genome sequence of Buchnera sp. strain APS, which is composed of one 640,681 base pair chromosome and two small plasmids [2]. Next, a draft genome sequence of the pea aphid was determined in 2010 [3]. In response to these genome sequence analyses, Shigenobu and Wilson present a refined picture of this symbiosis by linking pregenomic observations to new genomic data to understand the A. pisum/Buchnera APS symbiosis, including (1) lateral gene transfer, (2) host immunity, (3) symbiotic metabolism, and (4) regulation of symbiosis. Termites are insects that are able to vigorously decompose plant wood and therefore play an important role in carbon turnover in the global environment. Furthermore, nitrogen fixation in termites is one of the most important aspects of the symbiosis because the diet of termites is usually low in nitrogen sources [4]. Termites’ abilities to M. Kawaguchi (&) Division of Symbiotic Systems, National Institute for Basic Biology, Okazaki, Japan e-mail: Cell. Mol. Life Sci. (2011) 68:1283–1284 DOI 10.1007/s00018-011-0647-0 Cellular and Molecular Life Sciences

DOI: 10.1007/s00018-011-0647-0

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@article{Kawaguchi2011TheEO, title={The evolution of symbiotic systems}, author={Masayoshi Kawaguchi}, journal={Cellular and Molecular Life Sciences}, year={2011}, volume={68}, pages={1283-1284} }