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horizontal gene transfer

Marta Gibert, Sonia Paytubi, Sergi Beltrán, Antonio Juárez, Carlos Balsalobre, Cristina Madrid
Plasmids of the incompatibility group HI1 (IncHI1) have been isolated from several Gram-negative pathogens and are associated with the spread of multidrug resistance. Their conjugation is tightly regulated and it is inhibited at temperatures higher than 30°C, indicating that conjugation occurs outside warm-blooded hosts. Using R27, the prototype of IncHI1 plasmids, we report that plasmid transfer efficiency in E. coli strongly depends on the physiological state of the donor cells. Conjugation frequency is high when cells are actively growing, dropping sharply when cells enter the stationary phase of growth...
October 21, 2016: Environmental Microbiology
Carla Novais, Ana P Tedim, Val F Lanza, Ana R Freitas, Eduarda Silveira, Ricardo Escada, Adam P Roberts, Mohammed Al-Haroni, Fernando Baquero, Luísa Peixe, Teresa M Coque
Ampicillin resistance has greatly contributed to the recent dramatic increase of a cluster of human adapted Enterococcus faecium lineages (ST17, ST18, and ST78) in hospital-based infections. Changes in the chromosomal pbp5 gene have been associated with different levels of ampicillin susceptibility, leading to protein variants (designated as PBP5 C-types to keep the nomenclature used in previous works) with diverse degrees of reduction in penicillin affinity. Our goal was to use a comparative genomics approach to evaluate the relationship between the diversity of PBP5 among E...
2016: Frontiers in Microbiology
Gang Li, Mengyu Shen, Shuai Le, Yinling Tan, Ming Li, Xia Zhao, Wei Shen, Yuhui Yang, Jing Wang, Hongbin Zhu, Shu Li, Xiancai Rao, Fuquan Hu, Shuguang Lu
As a third-generation sequencing method, single-molecule real-time (SMRT) technology provides long read length, and it is well suited for re-sequencing projects and de novo assembly. In this study, Pseudomonas aeruginosa PA1 was characterized and re-sequenced using SMRT technology. PA1 was also subjected to genomic, comparative, and pan-genomic analyses. The multi-drug resistant strain PA1 possesses a 6,498,072 bp genome and a sequence type of ST-782. The genome of PA1 was also visualized, and the results revealed the details of general genome annotations, virulence factors, regulatory proteins, secretion system proteins, type II toxin-antitoxin pairs, and genomic islands...
October 20, 2016: Bioscience Reports
Félix LaRoche-Johnston, Caroline Monat, Benoit Cousineau
BACKGROUND: Group II introns are catalytically active RNA and mobile retroelements present in certain eukaryotic organelles, bacteria and archaea. These ribozymes self-splice from the pre-mRNA of interrupted genes and reinsert within target DNA sequences by retrohoming and retrotransposition. Evolutionary hypotheses place these retromobile elements at the origin of over half the human genome. Nevertheless, the evolution and dissemination of group II introns was found to be quite difficult to infer...
October 20, 2016: BMC Evolutionary Biology
Julia I Tandberg, Leidy X Lagos, Petter Langlete, Eva Berger, Anne-Lise Rishovd, Norbert Roos, Deepa Varkey, Ian T Paulsen, Hanne C Winther-Larsen
Membrane vesicles (MVs) are spherical particles naturally released from the membrane of Gram-negative bacteria. Bacterial MV production is associated with a range of phenotypes including biofilm formation, horizontal gene transfer, toxin delivery, modulation of host immune responses and virulence. This study reports comparative profiling of MVs from bacterial strains isolated from three widely disperse geographical areas. Mass spectrometry identified 119, 159 and 142 proteins in MVs from three different strains of Piscirickettsia salmonis isolated from salmonids in Chile (LF-89), Norway (NVI 5692) and Canada (NVI 5892), respectively...
2016: PloS One
Hemlata Hemlata, Arif Tasleem Jan, Archana Tiwari
Antibiotic resistance is a global problem exacerbated due to selective pressure of antimicrobial agents, spontaneous mutation, recombination and horizontal gene transfer. Of the different mechanisms that led to spread of resistance, one notorious phenomenon is the generation of Extended Spectrum β-lactamases (ESBLs) preferably TEM, SHV, OXA and CTX-M. Their production and frequent mobilization through horizontal gene transfer, made bacteria to exhibit resistance against a broad range of antibiotics. Resilient development of resistance among bacteria hampers available treatment options against different infections in the health care system...
October 14, 2016: Current Drug Metabolism
Tao Song, Hui Xu, Congchong Wei, Tengfei Jiang, Shishang Qin, Weijia Zhang, Yu Cao, Chao Hu, Fan Zhang, Dairong Qiao, Yi Cao
Seaweed is receiving an increasing amount of attention as a "sea vegetable". The microbiota of coastal populations may acquire seaweed associated enzymes through marine food. Several agarases have been found in non-marine environments; however, their origin is unknown. In this study, a hypothetical protein, Aga1, was identified as an agarase from an inland soil agar-degrading bacterium, Paenibacillus sp. SSG-1.Having low similarity to known glycoside hydrolases, Aga1 may be a distant member of the glycoside hydrolase family 86...
October 19, 2016: Scientific Reports
Jin Cai, Gengze Wu, Pedro A Jose, Chunyu Zeng
Extracellular vesicles (EVs) are small membrane vesicles including exosomes and shedding vesicles that mediated a cell-to-cell communication. EVs are released from almost all cell types under both physiological and pathological conditions and incorporate nuclear and cytoplasmic molecules for intercellular delivery. Besides protein, mRNA, and microRNA of these molecules, as recent studies show, specific DNA are prominently packaged into EVs. It appears likely that some of exosomes or shedding vesicles, bearing nuclear molecules are released upon bubble-like blebs...
October 14, 2016: Experimental Cell Research
Wenyao Chen, Tingzi Fang, Xiujuan Zhou, Daofeng Zhang, Xianming Shi, Chunlei Shi
The wide usage of antibiotics contributes to the increase in the prevalence of antibiotic-resistant Salmonella. Plasmids play a critical role in horizontal transfer of antibiotic resistance markers in Salmonella. This study aimed to screen and characterize plasmid profiles responsible for antibiotic resistance in Salmonella and ultimately to clarify the molecular mechanism of transferable plasmid-mediated antibiotic resistance. A total of 226 Salmonella isolates were examined for antimicrobial susceptibility by a disk diffusion method...
2016: Frontiers in Microbiology
Leise Riber, Mette Burmølle, Martin Alm, Stefan M Milani, Peter Thomsen, Lars H Hansen, Søren J Sørensen
The spread of antimicrobial resistance, usually mediated by horizontal transfer of plasmids, limits the options of treating bacterial infections and thereby poses a crucial human health problem. The disturbance of plasmid stability within bacterial species in clinical environments serves as a novel strategy to reduce the development and dissemination of antibiotic resistance. We tested the ability of irgasan to destabilize plasmids from Escherichia coli K-12 cells when added directly into liquid growth medium at concentrations below levels of marked bacterial growth inhibition, or when released into liquid growth medium from irgasan-impregnated Interpenetrating Polymer Network (IPN) silicone hydrogel objects, a novel technology developed as drug-delivery platform...
October 12, 2016: Plasmid
Randy Chi Fai Cheung, Tzi Bun Ng, Jack Ho Wong
Antifreeze proteins are ice-binding or ice-structuring proteins that prevent water from freezing by adsorbing to the ice surface and stopping the growth of minute ice crystals to large crystals in a non-colligative manner. The antifreeze proteins are found in species like fish, arthropods, plants, algae, fungi, yeasts and bacteria. The diversity, distribution and classification of antifreeze proteins were highlighted in this review. Antifreeze proteins help the organisms adapt to and survive in subzero temperature environments...
October 12, 2016: Current Protein & Peptide Science
Alvaro Molina-Cruz, Martine M Zilversmit, Daniel E Neafsey, Daniel L Hartl, Carolina Barillas-Mury
Plasmodium falciparum malaria remains a devastating public health problem. Recent discoveries have shed light on the origin and evolution of Plasmodium parasites and their interactions with their vertebrate and mosquito hosts. P. falciparum malaria originated in Africa from a single horizontal transfer between an infected gorilla and a human, and became global as the result of human migration. Today, P. falciparum malaria is transmitted worldwide by more than 70 different anopheline mosquito species. Recent studies indicate that the mosquito immune system can be a barrier to malaria transmission and that the P...
October 3, 2016: Annual Review of Genetics
Yu Nakashima, Yoko Egami, Miki Kimura, Toshiyuki Wakimoto, Ikuro Abe
Sponge metagenomes are a useful platform to mine cryptic biosynthetic gene clusters responsible for production of natural products involved in the sponge-microbe association. Since numerous sponge-derived bioactive metabolites are biosynthesized by the symbiotic bacteria, this strategy may concurrently reveal sponge-symbiont produced compounds. Accordingly, a metagenomic analysis of the Japanese marine sponge Discodermia calyx has resulted in the identification of a hybrid type I polyketide synthase-nonribosomal peptide synthetase gene (kas)...
2016: PloS One
Gábor Murányi, Mónika Szabó, Ferenc Olasz, János Kiss
The integrative genomic island SGI1 and its variants confer multidrug resistance in numerous Salmonella enterica serovariants and several Proteus mirabilis and Acinetobacter strains. SGI1 is mobilized by the IncA/C family plasmids. The island exploits not only the conjugation apparatus of the plasmid, but also utilizes the plasmid-encoded master regulator AcaCD to induce the excision and formation of its transfer-competent form, which is a key step in the horizontal transfer of SGI1. Triggering of SGI1 excision occurs via the AcaCD-dependent activation of xis gene expression...
2016: PloS One
Ingrid Palma-Martínez, Andrea Guerrero-Mandujano, Manuel J Ruiz-Ruiz, Cecilia Hernández-Cortez, José Molina-López, Virgilio Bocanegra-García, Graciela Castro-Escarpulli
Shiga-like toxins (Stx) represent a group of bacterial toxins involved in human and animal diseases. Stx is produced by enterohemorrhagic Escherichia coli, Shigella dysenteriae type 1, Citrobacter freundii, and Aeromonas spp.; Stx is an important cause of bloody diarrhea and hemolytic uremic syndrome (HUS). The aim of this study was to identify the stx1/stx2 genes in clinical strains and outer membrane vesicles (OMVs) of Aeromonas spp., 66 strains were isolated from children who live in Mexico City, and Stx effects were evaluated in Vero cell cultures...
2016: Frontiers in Microbiology
Laura Jetten, Leo van Iersel
Rooted phylogenetic networks are used to describe evolutionary histories that contain non-treelike evolutionary events such as hybridization and horizontal gene transfer. In some cases, such histories can be described by a phylogenetic base-tree with additional linking arcs, which can for example represent gene transfer events. Such phylogenetic networks are called tree-based. Here, we consider two possible generalizations of this concept to nonbinary networks, which we call tree-based and strictly-tree-based nonbinary phylogenetic networks...
October 7, 2016: IEEE/ACM Transactions on Computational Biology and Bioinformatics
Krupa M Parmar, Zubeen J Hathi, Nishant A Dafale
The spread of multidrug-resistant (MDR) bacteria is an emerging threat to the environment and public wellness. Inappropriate use and indiscriminate release of antibiotics in the environment through un-metabolized form create a scenario for the emergence of virulent pathogens and MDR bugs in the surroundings. Mechanisms underlying the spread of resistance include horizontal and vertical gene transfers causing the transmittance of MDR genes packed in different host, which pass across different food webs. Several controlling agents have been used for combating pathogens; however, the use of lytic bacteriophages proves to be one of the most eco-friendly due to their specificity, killing only target bacteria without damaging the indigenous beneficial flora of the habitat...
October 8, 2016: Applied Biochemistry and Biotechnology
W W Navarre
The H-NS family of DNA-binding proteins is the subject of intense study due to its important roles in the regulation of horizontally acquired genes critical for virulence, antibiotic resistance, and metabolism. Xenogeneic silencing proteins, typified by the H-NS protein of Escherichia coli, specifically target and downregulate expression from AT-rich genes by selectively recognizing specific structural features unique to the AT-rich minor groove. In doing so, these proteins facilitate bacterial evolution; enabling these cells to engage in horizontal gene transfer while buffering potential any detrimental fitness consequences that may result from it...
2016: Advances in Microbial Physiology
Chandan Pal, Johan Bengtsson-Palme, Erik Kristiansson, D G Joakim Larsson
BACKGROUND: Antibiotic resistance genes (ARGs) are widespread but cause problems only when present in pathogens. Environments where selection and transmission of antibiotic resistance frequently take place are likely to be characterized by high abundance and diversity of horizontally transferable ARGs. Large-scale quantitative data on ARGs is, however, lacking for most types of environments, including humans and animals, as is data on resistance genes to potential co-selective agents, such as biocides and metals...
October 7, 2016: Microbiome
Lukáš Novák, Zuzana Zubáčová, Anna Karnkowska, Martin Kolisko, Miluše Hroudová, Courtney W Stairs, Alastair G B Simpson, Patrick J Keeling, Andrew J Roger, Ivan Čepička, Vladimír Hampl
BACKGROUND: Multiple prokaryotic lineages use the arginine deiminase (ADI) pathway for anaerobic energy production by arginine degradation. The distribution of this pathway among eukaryotes has been thought to be very limited, with only two specialized groups living in low oxygen environments (Parabasalia and Diplomonadida) known to possess the complete set of all three enzymes. We have performed an extensive survey of available sequence data in order to map the distribution of these enzymes among eukaryotes and to reconstruct their phylogenies...
October 6, 2016: BMC Evolutionary Biology
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