Etude de l’effet mutagène lors d’une colonisation néonatale par une souche de Escherichia coli produisant la colibactine
Year: 2013
Type: dissertation
Abstract: Escherichia coli (E. coli) is one of the first commensal bacterium colonizing the intestinal tract of newborns. Within this highly versatile and ubiquitous bacterial species, some strains carry a genomic island pks containing the genes involved in the biosynthesis of a genotoxin named colibactin. This toxin induces DNA double-stranded breaks both in vitro in cultivated eukaryotic cells and in vivo in rodent intestinal cells. The peripartum period is a critical period during which the intestinal epithelium could be directly exposed to these early colonizing bacteria. In order to examine the consequences of the neonatal colonization by a colibactin-producing E. coli strain, the objectives of this project were (1) to determine the mutation frequency in a reporter gene (cII), integrated into the genome of eukaryotic cells infected by a pks+ E. coli strain, and (2) to map the contact points between bacteria and the intestinal tissue, and the DNA-damaged cells in a model of neonatal colonization. Generation of mutant cII allowed us to show a significant increase of cII-mutant frequency in cells infected by pks+ bacteria, and to construct a cII-mutant gene library of which sequencing permit to characterize the nature of colibactin-induced mutations. Our experiments have also put in light in vivo dynamic spatial distribution of DNA damage, from intestinal crypts to surface epithelium, in relation to the developmental stage of the intestinal mucosa. This work establishes a basis for the study of mutagenesis resulting from neonatal acquisition of a colibactin-producing E. coli strain.
Source: HAL
Author: Emilie Cloup
Language: French
Subfield: Microbiology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2262407055