The coevolution of gene mobility and sociality in bacteria

Bacteria are social organisms which participate in multiple cooperative and group behaviours. They moreover have peculiar genetic systems, as they often bear mobile genetic elements like plasmids, molecular symbionts that are the cause of widespread horizontal gene transfer and play a large role in...

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Main Author: Dimitriu, Tatiana
Language:English
Published: Université René Descartes - Paris V 2014
Subjects:
Online Access:http://tel.archives-ouvertes.fr/tel-00993436
http://tel.archives-ouvertes.fr/docs/00/99/34/36/PDF/vd_dimitriu_tatiana.pdf
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spelling ndltd-CCSD-oai-tel.archives-ouvertes.fr-tel-009934362014-05-21T03:32:44Z http://tel.archives-ouvertes.fr/tel-00993436 2014PA05T005 http://tel.archives-ouvertes.fr/docs/00/99/34/36/PDF/vd_dimitriu_tatiana.pdf The coevolution of gene mobility and sociality in bacteria Dimitriu, Tatiana [SDV:SA] Life Sciences/Agricultural sciences [SDV:SA] Sciences du Vivant/Sciences agricoles Horizontal gene transfer Plasmids Bacterial cooperation Mobile genetic elements Bacteria are social organisms which participate in multiple cooperative and group behaviours. They moreover have peculiar genetic systems, as they often bear mobile genetic elements like plasmids, molecular symbionts that are the cause of widespread horizontal gene transfer and play a large role in bacterial evolution. Both cooperation and horizontal transfer have consequences for human health: cooperative behaviours are very often involved in the virulence of pathogens, and horizontal gene transfer leads to the spread of antibiotic resistance. The evolution of plasmid transfer has mainly been analyzed in terms of infectious benefits for selfish mobile elements. However, chromosomal genes can also modulate horizontal transfer. A huge diversity in transfer rates is observed among bacterial isolates, suggesting a complex co-evolution between plasmids and hosts. Moreover, plasmids are enriched in genes involved in social behaviours, and so could play a key role in bacterial cooperative behaviours. We study here the coevolution of gene mobility and sociality in bacteria. To investigate the selective pressures acting on plasmid transfer and public good production, we use both mathematical modelling and a synthetic system that we constructed where we can independently control public good cooperation and plasmid conjugation in Escherichia coli. We first show experimentally that horizontal transfer allows the specific maintenance of public good alleles in a structured population by increasing relatedness at the gene-level. We further demonstrate experimentally and theoretically that this in turn allows for second-order selection of transfer ability: when cooperation is needed, alleles promoting donor and recipient abilities for public good traits can be selected both on the plasmid and on the chromosome in structured populations. Moreover, donor ability for private good traits can also be selected on the chromosome, provided that transfer happens towards kin. The interactions between transfer and cooperation can finally lead to an association between transfer and public good production alleles, explaining the high frequency of genes related to cooperation that are located on plasmids. Globally, these results provide insight into the mechanisms maintaining cooperation in bacteria, and may suggest ways to target cooperative virulence. 2014-04-09 eng PhD thesis Université René Descartes - Paris V
collection NDLTD
language English
sources NDLTD
topic [SDV:SA] Life Sciences/Agricultural sciences
[SDV:SA] Sciences du Vivant/Sciences agricoles
Horizontal gene transfer
Plasmids
Bacterial cooperation
Mobile genetic elements
spellingShingle [SDV:SA] Life Sciences/Agricultural sciences
[SDV:SA] Sciences du Vivant/Sciences agricoles
Horizontal gene transfer
Plasmids
Bacterial cooperation
Mobile genetic elements
Dimitriu, Tatiana
The coevolution of gene mobility and sociality in bacteria
description Bacteria are social organisms which participate in multiple cooperative and group behaviours. They moreover have peculiar genetic systems, as they often bear mobile genetic elements like plasmids, molecular symbionts that are the cause of widespread horizontal gene transfer and play a large role in bacterial evolution. Both cooperation and horizontal transfer have consequences for human health: cooperative behaviours are very often involved in the virulence of pathogens, and horizontal gene transfer leads to the spread of antibiotic resistance. The evolution of plasmid transfer has mainly been analyzed in terms of infectious benefits for selfish mobile elements. However, chromosomal genes can also modulate horizontal transfer. A huge diversity in transfer rates is observed among bacterial isolates, suggesting a complex co-evolution between plasmids and hosts. Moreover, plasmids are enriched in genes involved in social behaviours, and so could play a key role in bacterial cooperative behaviours. We study here the coevolution of gene mobility and sociality in bacteria. To investigate the selective pressures acting on plasmid transfer and public good production, we use both mathematical modelling and a synthetic system that we constructed where we can independently control public good cooperation and plasmid conjugation in Escherichia coli. We first show experimentally that horizontal transfer allows the specific maintenance of public good alleles in a structured population by increasing relatedness at the gene-level. We further demonstrate experimentally and theoretically that this in turn allows for second-order selection of transfer ability: when cooperation is needed, alleles promoting donor and recipient abilities for public good traits can be selected both on the plasmid and on the chromosome in structured populations. Moreover, donor ability for private good traits can also be selected on the chromosome, provided that transfer happens towards kin. The interactions between transfer and cooperation can finally lead to an association between transfer and public good production alleles, explaining the high frequency of genes related to cooperation that are located on plasmids. Globally, these results provide insight into the mechanisms maintaining cooperation in bacteria, and may suggest ways to target cooperative virulence.
author Dimitriu, Tatiana
author_facet Dimitriu, Tatiana
author_sort Dimitriu, Tatiana
title The coevolution of gene mobility and sociality in bacteria
title_short The coevolution of gene mobility and sociality in bacteria
title_full The coevolution of gene mobility and sociality in bacteria
title_fullStr The coevolution of gene mobility and sociality in bacteria
title_full_unstemmed The coevolution of gene mobility and sociality in bacteria
title_sort coevolution of gene mobility and sociality in bacteria
publisher Université René Descartes - Paris V
publishDate 2014
url http://tel.archives-ouvertes.fr/tel-00993436
http://tel.archives-ouvertes.fr/docs/00/99/34/36/PDF/vd_dimitriu_tatiana.pdf
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