Molecular Characterization of the Principal Symbiotic Bacteria of the Weevil Sitophilus oryzae: A Peculiar G + C Content of an Endocytobiotic DNA |
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Authors: | Abdelaziz Heddi Hubert Charles Chaqué Khatchadourian Guy Bonnot Paul Nardon |
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Institution: | (1) Laboratoire de Biologie Appliquée, INSA 406 UA-INRA 203 SDI-CNRS 5128, 20, Avenue Albert Einstein, 69621 Villeurbanne Cedex, France, FR |
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Abstract: | The principal intracellular symbiotic bacteria of the cereal weevil Sitophilus oryzae were characterized using the sequence of the 16S rDNA gene (rrs gene) and G + C content analysis. Polymerase chain reaction amplification with universal eubacterial primers of the rrs gene showed a single expected sequence of 1,501 bp. Comparison of this sequence with the available database sequences placed
the intracellular bacteria of S. oryzae as members of the Enterobacteriaceae family, closely related to the free-living bacteria, Erwinia herbicola and Escherichia coli, and the endocytobiotic bacteria of the tsetse fly and aphids. Moreover, by high-performance liquid chromatography, we measured
the genomic G + C content of the S. oryzae principal endocytobiotes (SOPE) as 54%, while the known genomic G + C content of most intracellular bacteria is about 39.5%.
Furthermore, based on the third codon position G + C content and the rrs gene G + C content, we demonstrated that most intracellular bacteria except SOPE are A + T biased irrespective of their phylogenetic
position. Finally, using the hsp60 gene sequence, the codon usage of SOPE was compared with that of two phylogenetically closely related bacteria: E. coli, a free-living bacterium, and Buchnera aphidicola, the intracellular symbiotic bacteria of aphids. Taken together, these results show a peculiar and distinctly different DNA
composition of SOPE with respect to the other obligate intracellular bacteria, and, combined with biological and biochemical
data, they elucidate the evolution of symbiosis in S. oryzae.
Received: 8 September 1997 / Accepted: 24 October 1997 |
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Keywords: | : Symbiosis — Sitophilus oryzae— Phylogeny — DNA composition — Intracellular bacteria — Codon usage |
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