Frontiers in microbiology
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Frontiers in microbiology · Jan 2014
ReviewCoronavirus infection, ER stress, apoptosis and innate immunity.
The replication of coronavirus, a family of important animal and human pathogens, is closely associated with the cellular membrane compartments, especially the endoplasmic reticulum (ER). Coronavirus infection of cultured cells was previously shown to cause ER stress and induce the unfolded protein response (UPR), a process that aims to restore the ER homeostasis by global translation shutdown and increasing the ER folding capacity. However, under prolonged ER stress, UPR can also induce apoptotic cell death. ⋯ Activation of the three branches of UPR modulates a wide variety of signaling pathways, such as mitogen-activated protein (MAP) kinase activation, autophagy, apoptosis, and innate immune response. ER stress and UPR activation may therefore contribute significantly to the viral replication and pathogenesis during coronavirus infection. In this review, we summarize the current knowledge on coronavirus-induced ER stress and UPR activation, with emphasis on their cross-talking to apoptotic signaling.
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Frontiers in microbiology · Jan 2014
ReviewLearning from agriculture: understanding low-dose antimicrobials as drivers of resistome expansion.
Antimicrobial resistance is a growing public health challenge worldwide, with agricultural use of antimicrobials being one major contributor to the emergence and dissemination of antimicrobial resistance (AMR). Globally, most antimicrobials are used in industrial food animal production, a major context for microbiomes encountering low-doses or subtherapeutic-levels of antimicrobial agents from all mechanistic classes. This modern practice exerts broad eco-evolutionary effects on the gut microbiome of food animals, which is subsequently transferred to animal waste. ⋯ Unconfined storage or land deposition of a large volume of animal waste causes its wide contact with the environment and drives the expansion of the environmental resistome through mobilome facilitated horizontal genet transfer. The expanded environmental resistome, which encompasses both natural constituents and anthropogenic inputs, can persist under multiple stressors from agriculture and may re-enter humans, thus posing a public health risk to humans. For these reasons, this review focuses on agricultural antimicrobial use as a laboratory for understanding low-dose antimicrobials as drivers of resistome expansion, briefly summarizes current knowledge on this topic, highlights the importance of research specifically on environmental microbial ecosystems considering AMR as environmental pollution, and calls attention to the needs for longitudinal studies at the systems level.
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Frontiers in microbiology · Jan 2014
Selection of target mutation in rat gastrointestinal tract E. coli by minute dosage of enrofloxacin.
It has been suggested that bacterial resistance is selected within a mutation selection window of antibiotics. More recent studies showed that even extremely low concentration of antibiotic could select resistant bacteria in vitro. Yet little is known about the exact antibiotic concentration range that can effectively select for resistant organisms in animal gastrointestinal (GI) tract. ⋯ Surprisingly, very low dose of enrofloxacin (1/1000 therapeutic dose) could also select for mutation in GI tract E. coli at the later course of enrofloxacin treatment, only with slightly lower efficiency. No enrofloxacin-resistant E. coli could be selected at all test levels of enrofloxacin during long term treatment and the strength of antibiotic treatment does not alter the overall level of E. coli in rat GI tract. This study demonstrated that long term antibiotic treatment seems to be the major trigger for the development of target mutations in GI tract E. coli, which provided insight into the rational use of antibiotics in animal husbandry.
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Frontiers in microbiology · Jan 2014
Assessing impacts of unconventional natural gas extraction on microbial communities in headwater stream ecosystems in Northwestern Pennsylvania.
Hydraulic fracturing and horizontal drilling have increased dramatically in Pennsylvania Marcellus shale formations, however the potential for major environmental impacts are still incompletely understood. High-throughput sequencing of the 16S rRNA gene was performed to characterize the microbial community structure of water, sediment, bryophyte, and biofilm samples from 26 headwater stream sites in northwestern Pennsylvania with different histories of fracking activity within Marcellus shale formations. Further, we describe the relationship between microbial community structure and environmental parameters measured. ⋯ Further, several of these OTUs were strongly negatively correlated with pH and positively correlated with the number of wellpads in a watershed. It should be noted that many of the OTUs enriched in MSA+ sites are putative acidophilic and/or methanotrophic populations. This study revealed apparent shifts in the autochthonous microbial communities and highlighted potential members that could be responding to changing stream conditions as a result of nascent industrial activity in these aquatic ecosystems.