The 160-Kilobase Genome of the Bacterial Endosymbiont
            <i>Carsonella</i>

Nakabachi, Atsushi; Yamashita, Atsushi; Toh, Y.; Ishikawa, Hajime; Dunbar, Helen E.; Moran, Nancy A.; Hattori, Masahira

doi:10.1126/science.1134196

Cited by 517 publications

(481 citation statements)

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“…The upregulation of essential amino-acid biosynthesis genes in co-culture suggests that their production may also benefit the host and other community members, as these essential amino acids are often implicated in insect/bacteria symbioses (Shigenobu et al, 2000;Gil et al, 2003;Nakabachi et al, 2006). The recently published genomes of two endosymbionts of termite-gut protozoa have also suggested the importance of other aspects of amino-acid and vitamin production in the symbiosis (Hongoh et al, 2008a, b).…”

Section: Od 600nmmentioning

confidence: 99%

“…In return, many such endosymbionts act almost exclusively as essential amino acids and vitamin factories, capable of little else (Shigenobu et al, 2000;Akman et al, 2002;Gil et al, 2003;Nakabachi et al, 2006). In contrast, these termite-gut spirochetes are not intracellular residents of their host's tissues, and have comparatively large genomes, suggesting that they are capable of performing many more tasks in their species-rich symbiotic environment than their endosymbiontic counterparts.…”

Section: Od 600nmmentioning

confidence: 99%

“…The genomes of intracellular endosymbionts of insects are often highly reduced (Shigenobu et al, 2000;Akman et al, 2002;Gil et al, 2003;Nakabachi et al, 2006;Hongoh et al, 2008a, b) and underlie the obligate reliance of these bacteria on nutrients and factors supplied by the host. In return, many such endosymbionts act almost exclusively as essential amino acids and vitamin factories, capable of little else (Shigenobu et al, 2000;Akman et al, 2002;Gil et al, 2003;Nakabachi et al, 2006).…”

Section: Od 600nmmentioning

confidence: 99%

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RNA-seq reveals cooperative metabolic interactions between two termite-gut spirochete species in co-culture

et al. 2011

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The hindguts of wood-feeding termites typically contain hundreds of microbial species. Together with their insect host, these gut microbes degrade lignocellulose into usable catabolites. Although past research revealed many facets of the stepwise flow of metabolites in this scheme, not much is known about the breadth of interactions occurring between termite-gut microbes. Most of these microbes are thought to depend on, and to have co-speciated with, their host and each other for millions of years. In this study, we explored the interactions of two spirochetes previously isolated from the very same termite species. As hydrogen (H 2 ) is the central free intermediate in termite-gut lignocellulose digestion, we focused on interactions between two closely related termite-gut spirochetes possessing complementary H 2 physiologies: one produces H 2 , while the other consumes it. In vitro, these two Treponema species markedly enhanced each other's growth. RNA sequencing resolved the transcriptomes of these two closely related organisms, revealing that co-cultivation causes comprehensive changes in global gene expression. The expression of well over a 100 genes in each species was changed 4twofold, with over a dozen changed 410-fold. Several changes implicating synergistic cross-feeding of known metabolites were validated in vitro. Additionally, certain activities beneficial to the host were preferentially expressed during consortial growth. However, the majority of changes in gene expression are not yet understandable, but indicate a broad, comprehensive and mutualistic interaction between these closely related, co-resident gut symbionts. The results suggest that staggeringly intricate networks of metabolic and gene interactions drive lignocellulose degradation and co-evolution of termite gut microbiota.

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Section: Od 600nmmentioning

confidence: 99%

Section: Od 600nmmentioning

confidence: 99%

Section: Od 600nmmentioning

confidence: 99%

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RNA-seq reveals cooperative metabolic interactions between two termite-gut spirochete species in co-culture

et al. 2011

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“…Primary symbionts tend to be purely vertically transmitted, and many of the associations with their insect partners are ancient (reviewed in [8]); the oldest known insect symbiont Sulcia muelleri, for example, has been associated with the Auchenorrhyncha for the past 270 Myr [10]. Typically, the primary symbiont's genome is extremely reduced [11], and at least in some cases, their gene content can be predicted based on knowledge of their lifestyle [12]. Even though the genome of primary symbionts can be extremely stable in terms of chromosome arrangements and gene content, there is evidence of rapid sequence evolution between closely related strains [13].…”

Section: Are Heritable Endosymbionts Affecting Important Ecological Tmentioning

confidence: 99%

Bacterial symbionts in insects or the story of communities affecting communities

Ferrari

Vavre

2011

Phil. Trans. R. Soc. B

307

280

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Bacterial symbionts are widespread in insects and other animals. Most of them are predominantly vertically transmitted, along with their hosts' genes, and thus extend the heritable genetic variation present in one species. These passengers have a variety of repercussions on the host's phenotypes: besides the cost imposed on the host for maintaining the symbiont population, they can provide fitness advantages to the host or manipulate the host's reproduction. We argue that insect symbioses are ideal model systems for community genetics. First, bacterial symbionts directly or indirectly affect the interactions with other species within a community. Examples include their involvement in modifying the use of host plants by phytophagous insects, in providing resistance to natural enemies, but also in reducing the global genetic diversity or gene flow between populations within some species. Second, one emerging picture in insect symbioses is that many species are simultaneously infected with more than one symbiont, which permits studying the factors that shape bacterial communities; for example, horizontal transmission, interactions between host genotype, symbiont genotype and the environment and interactions among symbionts. One conclusion is that insects' symbiotic complements are dynamic communities that affect and are affected by the communities in which they are embedded.

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“…The current repertoire of fully sequenced bacterial genomes spans a significant portion of this diversity; for example, sequenced representatives of 20 bacterial phyla are available, with genome sizes ranging from 0.16 to over 13 Mb (Nakabachi et al 2006;Schneiker et al 2007). The diversity observed among bacterial genomes results from the interplay among mutation, natural selection, and genetic drift.…”

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confidence: 99%

The consequences of genetic drift for bacterial genome complexity

2009

Self Cite

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Genetic drift, which is particularly effective within small populations, can shape the size and complexity of genomes by affecting the fixation of deleterious mutations. In Bacteria, assessing the contribution of genetic drift to genome evolution is problematic because the usual methods, based on intraspecific polymorphisms, can be thwarted by difficulties in delineating species' boundaries. The increased availability of sequenced bacterial genomes allows application of an alternative estimator of drift, the genome-wide ratio of replacement to silent substitutions in protein-coding sequences. This ratio, which reflects the action of purifying selection across the entire genome, shows a strong inverse relationship with genome size, indicating that drift promotes genome reduction in bacteria.

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The 160-Kilobase Genome of the Bacterial Endosymbiont Carsonella

Cited by 517 publications

References 5 publications

RNA-seq reveals cooperative metabolic interactions between two termite-gut spirochete species in co-culture

RNA-seq reveals cooperative metabolic interactions between two termite-gut spirochete species in co-culture

Bacterial symbionts in insects or the story of communities affecting communities

The consequences of genetic drift for bacterial genome complexity

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