Search results for "serra"

Data from: Evolution of bacterial life history traits is sensitive to community structure

2016

Very few studies have experimentally assessed the evolutionary effects of species interactions within the same trophic level. Here we show that when Serratia marcescens evolve in multispecies communities, their growth rate exceeds the growth rate of the bacteria that evolved alone, whereas the biomass yield gets lower. In addition to the community effects per se, we found that few species in the communities caused strong effects on S. marcescens evolution. The results indicate that evolutionary responses (of a focal species) are different in communities, compared to species evolving alone. Moreover, selection can lead to very different outcomes depending on the community structure. Such con…

Data from: Propagule pressure increase and phylogenetic diversity decrease community’s susceptibility to invasion

2017

Invasions pose a large threat to native species, but the question of why some species are more invasive, and some communities more prone to invasions than others, is far from solved. Using ten different three-species bacterial communities, we tested experimentally if the phylogenetic relationships between an invader and a resident community and propagule pressure affect invasion probability. We found that greater diversity in phylogenetic distances between the resident community members and the invader lowered invasion success, and higher propagule pressure increased invasion success whereas phylogenetic distance had no clear effect. In the later stages of invasion phylogenetic diversity ha…

Data from: A mechanistic underpinning for sigmoid dose-dependent infection

2016

Theoretical models of environmentally transmitted diseases often assume that transmission is a constant process, which scales linearly with pathogen dose. Here we question the applicability of such an assumption and propose a sigmoidal form for the pathogens infectivity response. In our formulation, this response arises under two assumptions: 1) multiple invasion events are required for a successful pathogen infection and 2) the host invasion state is reversible. The first assumption reduces pathogen infection rates at low pathogen doses, while the second assumption, due to host immune function, leads to a saturating infection rate at high doses. The derived pathogen dose:infection rate -re…

Data from: Fluctuating temperature leads to evolution of thermal generalism and preadaptation to novel environments

2013

Environmental fluctuations can select for generalism, which is also hypothesized to increase organisms’ ability to invade novel environments. Here, we show that across a range of temperatures, opportunistic bacterial pathogen Serratia marcescens that evolved in fluctuating temperature (daily variation between 24°C and 38°C, mean 31°C) outperforms the strains that evolved in constant temperature (31°C). The growth advantage was also evident in novel environments in the presence of parasitic viruses and predatory protozoans, but less clear in the presence of stressful chemicals. Adaptation to fluctuating temperature also led to reduced virulence in Drosophila melanogaster host, which suggests…

Data from: Conjugation is necessary for a bacterial plasmid to survive under protozoan predation

2016

Horizontal gene transfer by conjugative plasmids plays a critical role in the evolution of antibiotic resistance. Interactions between bacteria and other organisms can affect the persistence and spread of conjugative plasmids. Here we show that protozoan predation increased the persistence and spread of the antibiotic resistance plasmid RP4 in populations of the opportunist bacterial pathogen Serratia marcescens. A conjugation-defective mutant plasmid was unable to survive under predation, suggesting that conjugative transfer is required for plasmid persistence under the realistic condition of predation. These results indicate that multi-trophic interactions can affect the maintenance of co…

Lower extremity soft tissue defect reconstruction with the serratus anterior flap

2013

Reconstruction of limb-threatening lower extremity defects presents unique challenges. The selected method must provide adequate coverage of exposed bone, joints, and tendons while maximizing function of the limb. The traditional workhorse flaps, the free latissimus dorsi and rectus abdominis flaps, have been associated with donor site morbidity and bulkiness that can impair rehabilitation. We report a case series (n = 18) in which the free serratus anterior muscle flap and split thickness skin graft (STSG) was used for lower limb soft tissue coverage. Injuries were due to diabetes (9/18), trauma (7/18), and chronic venous stasis (2/18). A 94% flap survival rate was observed and all but one…

Excess volatiles supplied by mingling of mafic magma at an andesite arc volcano

2010

We present the results of a study of volcanic gases at Soufriere Hills Volcano, Montserrat, which includes the first spectroscopic measurements of the major gas species CO2 and H2S at this volcano using a Multisensor Gas Analyzer System (MultiGAS) sensor. The fluxes of CO2 and H2S were 640.2750 t/d and 84.266 t/d, respectively, during July 2008, during a prolonged eruptive pause. The flux of CO2 is similar to estimates for the entire arc from previous geochemical studies, while the measured H2S flux significantly alters our interpretation of the sulphur budget for this volcano. The fluxes of both sulphur and carbon show considerable excesses over that which can be supplied by degassing of e…

Predation on Multiple Trophic Levels Shapes the Evolution of Pathogen Virulence

2009

The pathogen virulence is traditionally thought to co-evolve as a result of reciprocal selection with its host organism. In natural communities, pathogens and hosts are typically embedded within a web of interactions with other species, which could affect indirectly the pathogen virulence and host immunity through trade-offs. Here we show that selection by predation can affect both pathogen virulence and host immune defence. Exposing opportunistic bacterial pathogen Serratia marcescens to predation by protozoan Tetrahymena thermophila decreased its virulence when measured as host moth Parasemia plantaginis survival. This was probably because the bacterial anti-predatory traits were traded o…

The effect of prey resources on evolutionary and ecological dynamics of prey (Serratia marcescens) and predator (Tetrahymena thermophila)

2006

The effect of a temperature-sensitive prophage on the evolution of virulence in an opportunistic bacterial pathogen.

2022

https://doi.org/10.1111/mec.16638 Abstract Viruses are key actors of ecosystems and have major impacts on global biogeochemical cycles. Prophages deserve particular attention as they are ubiquitous in bacterial genomes and can enter a lytic cycle when triggered by environmental conditions. We explored how temperature affects the interactions between prophages and other biological levels by using an opportunistic pathogen, the bacterium Serratia marcescens, that harbours several prophages and that had undergone an evolution experiment under several temperature regimes. We found that the release of one of the prophages was temperature-sensitive and malleable to evolutionary changes. We furthe…