Emerging patterns of plasmid-host coevolution that stabilize antibiotic resistance.

Multidrug resistant bacterial pathogens have become a serious global human health threat, and conjugative plasmids are important drivers of the rapid spread of resistance to last-resort antibiotics. Whereas antibiotics have been shown to select for adaptation of resistance plasmids to their new bacterial hosts, or vice versa, a general evolutionary mechanism has not yet emerged. Here we conducted an experimental evolution study aimed at determining general patterns of plasmid-bacteria evolution.

Evolved plasmid-host interactions reduce plasmid interference cost.

Antibiotic selection drives adaptation of antibiotic resistance plasmids to new bacterial hosts, but the molecular mechanisms are still poorly understood. We previously showed that a broad-host-range plasmid was poorly maintained in Shewanella oneidensis, but rapidly adapted through mutations in the replication initiation gene trfA1. Here we examined if these mutations reduced the fitness cost of TrfA1, and whether this was due to changes in interaction with the host's DNA helicase DnaB.

Evolutionary Paths That Expand Plasmid Host-Range: Implications for Spread of Antibiotic Resistance.

The World Health Organization has declared the emergence of antibiotic resistance to be a global threat to human health. Broad-host-range plasmids have a key role in causing this health crisis because they transfer multiple resistance genes to a wide range of bacteria. To limit the spread of antibiotic resistance, we need to gain insight into the mechanisms by which the host range of plasmids evolves.

Diverse broad-host-range plasmids from freshwater carry few accessory genes.

Broad-host-range self-transferable plasmids are known to facilitate bacterial adaptation by spreading genes between phylogenetically distinct hosts. These plasmids typically have a conserved backbone region and a variable accessory region that encodes host-beneficial traits. We do not know, however, how well plasmids that do not encode accessory functions can survive in nature.

Host range diversification within the IncP-1 plasmid group.

Broad-host-range plasmids play a critical role in the spread of antibiotic resistance and other traits. In spite of increasing information about the genomic diversity of closely related plasmids, the relationship between sequence divergence and host range remains unclear. IncP-1 plasmids are currently classified into six subgroups based on the genetic distance of backbone genes.

Comparative genomics of IncP-1ε plasmids from water environments reveals diverse and unique accessory genetic elements.

The goal of this study was to determine and compare the complete genome sequences of three new broad-host-range conjugative plasmids. Plasmids pMLUA1, pMLUA3 and pMLUA4 were previously recovered from estuarine water by exogenous plasmid isolation and ranged in size from ∼55 to 59 kb. Comparative genomics showed that their backbone region was identical to the prototype pKJK5 and other IncP1-ε plasmids captured from soils.

Invasion of E. coli biofilms by antibiotic resistance plasmids.

In spite of the contribution of plasmids to the spread of antibiotic resistance in human pathogens, little is known about the transferability of various drug resistance plasmids in bacterial biofilms. The goal of this study was to compare the efficiency of transfer of 19 multidrug resistance plasmids into Escherichia coli recipient biofilms and determine the effects of biofilm age, biofilm-donor exposure time, and donor-to-biofilm attachment on this process. An E.

The complete genome sequences of four new IncN plasmids from wastewater treatment plant effluent provide new insights into IncN plasmid diversity and evolution.

The dissemination of antibiotic resistance genes among bacteria often occurs by means of plasmids. Wastewater treatment plants (WWTP) were previously recognized as hot spots for the horizontal transfer of genetic material. One of the plasmid groups that is often associated with drug resistance is the incompatibility group IncN.

Roles of long and short replication initiation proteins in the fate of IncP-1 plasmids.

Broad-host-range IncP-1 plasmids generally encode two replication initiation proteins, TrfA1 and TrfA2. TrfA2 is produced from an internal translational start site within trfA1. While TrfA1 was previously shown to be essential for replication in Pseudomonas aeruginosa, its role in other bacteria within its broad host range has not been established.

Broad-host-range plasmids from agricultural soils have IncP-1 backbones with diverse accessory genes.

Broad-host-range plasmids are known to spread genes between distinct phylogenetic groups of bacteria. These genes often code for resistances to antibiotics and heavy metals or degradation of pollutants. Although some broad-host-range plasmids have been extensively studied, their evolutionary history and genetic diversity remain largely unknown.

Increased transfer of a multidrug resistance plasmid in Escherichia coli biofilms at the air-liquid interface.

Although biofilms represent a common bacterial lifestyle in clinically and environmentally important habitats, there is scant information on the extent of gene transfer in these spatially structured populations. The objective of this study was to gain insight into factors that affect transfer of the promiscuous multidrug resistance plasmid pB10 in Escherichia coli biofilms. Biofilms were grown in different experimental settings, and plasmid transfer was monitored using laser scanning confocal microscopy and plate counting.

Sequencing and comparative analysis of IncP-1α antibiotic resistance plasmids reveal a highly conserved backbone and differences within accessory regions.

Although IncP-1 plasmids are important for horizontal gene transfer among bacteria, in particular antibiotic resistance spread, so far only three plasmids from the subgroup IncP-1α have been completely sequenced. In this study we doubled this number. The three IncP-1α plasmids pB5, pB11 and pSP21 were isolated from bacteria of two different sewage treatment plants and sequenced by a combination of next-generation and capillary sequencing technologies.

Dual reporter system for in situ detection of plasmid transfer under aerobic and anaerobic conditions.

We designed a new genetic tool to detect plasmid transfer under anaerobic and aerobic conditions. The system is based on the T7 RNA polymerase gene and a T7 promoter-driven oxygen-independent green fluorescent protein, evoglow, alone or in combination with red fluorescent protein DsRed. Constructs are available as plasmids and mini-mariner transposons.

Cardioprotective effects of cerium oxide nanoparticles in a transgenic murine model of cardiomyopathy.

Objective: Cerium oxide (CeO2) nanoparticles have been shown to protect cells in culture from lethal stress, but no protection in vivo has been reported. Cardiac-specific expression of monocyte chemoattractant protein (MCP)-1 in mice causes ischemic cardiomyopathy associated with activation of endoplasmic reticulum (ER) stress. The aim of this study was to assess the effects of CeO2 nanoparticles on cardiac function and remodeling as well as ER stress response in this murine model of cardiomyopathy.

Activation of endoplasmic reticulum stress response during the development of ischemic heart disease.

Endoplasmic reticulum (ER) stress has been found to be associated with neurodegenerative diseases and diabetes mellitus. Whether ER stress is involved in the development of heart disease is not known. Cardiac-specific expression of monocyte chemoattractant protein-1 (MCP-1) in mice causes the development of ischemic heart disease.

Homoserine and asparagine are host signals that trigger in planta expression of a pathogenesis gene in Nectria haematococca.

Some pathogenesis-related genes are expressed in fungi only when the pathogen is in the host, but the host signals that trigger these gene expressions have not been identified. Virulent Nectria haematococca infects pea plants and requires either pelA, which is induced by pectin, or pelD, which is induced only in planta. However, the host signal(s) that trigger pelD expression was unknown.