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1.
J Vis Exp ; (203)2024 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-38251745

RESUMO

Temperate phages are found integrated as prophages in the majority of bacterial genomes. Some prophages are cryptic and fixed in the bacterial chromosome, but others are active and can be triggered into a replicative form either spontaneously or by exposure to inducing factors. Prophages are commonly associated with the ability to confer toxin production or other virulence-associated traits on their host cell. More recent studies have shown they can play a much bigger role in altering the physiology of their hosts. The technique described here has enabled us to investigate how prophages affect gene expression in the opportunistic bacterium Pseudomonas aeruginosa. In this work, the growth of the wild-type P. aeruginosa strain PAO1 was compared with that of isogenic lysogens carrying different combinations of prophages from the Liverpool Epidemic Strain (LES) LESB58. In a lysogen culture, a proportion of bacterial cells will be supporting lytic bacteriophage replication (spontaneous induction) with a high level of expression per cell of late phage genes, such as those associated with the assembly of phage particles, thus masking the low-level gene expression associated with lysogen-restricted gene expression. The impact of spontaneous induction can thus obscure prophage gene expression across a lysogen population. Growth profiling experiments were used to identify spontaneous induction, which was minimal during the early exponential growth phase. This study reports how to prepare sample cultures during the early exponential growth phase and how to set up adequate controls despite low cell numbers. These protocols ensure the reliable and reproducible comparison of wild-type and lysogenic bacteria under various conditions, thus improving the transcriptomic profiling of prophage genomes and aiding in the identification of previously unrecognized prophage functions.


Assuntos
Bacteriófagos , Bacteriófagos/genética , Perfilação da Expressão Gênica , Técnicas de Tipagem Bacteriana , Contagem de Células , Cromossomos Bacterianos
2.
Nature ; 625(7996): 735-742, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38030727

RESUMO

Noncoding DNA is central to our understanding of human gene regulation and complex diseases1,2, and measuring the evolutionary sequence constraint can establish the functional relevance of putative regulatory elements in the human genome3-9. Identifying the genomic elements that have become constrained specifically in primates has been hampered by the faster evolution of noncoding DNA compared to protein-coding DNA10, the relatively short timescales separating primate species11, and the previously limited availability of whole-genome sequences12. Here we construct a whole-genome alignment of 239 species, representing nearly half of all extant species in the primate order. Using this resource, we identified human regulatory elements that are under selective constraint across primates and other mammals at a 5% false discovery rate. We detected 111,318 DNase I hypersensitivity sites and 267,410 transcription factor binding sites that are constrained specifically in primates but not across other placental mammals and validate their cis-regulatory effects on gene expression. These regulatory elements are enriched for human genetic variants that affect gene expression and complex traits and diseases. Our results highlight the important role of recent evolution in regulatory sequence elements differentiating primates, including humans, from other placental mammals.


Assuntos
Sequência Conservada , Evolução Molecular , Genoma , Primatas , Animais , Feminino , Humanos , Gravidez , Sequência Conservada/genética , Desoxirribonuclease I/metabolismo , DNA/genética , DNA/metabolismo , Genoma/genética , Mamíferos/classificação , Mamíferos/genética , Placenta , Primatas/classificação , Primatas/genética , Sequências Reguladoras de Ácido Nucleico/genética , Reprodutibilidade dos Testes , Fatores de Transcrição/metabolismo , Proteínas/genética , Regulação da Expressão Gênica/genética
3.
Science ; 380(6648): 906-913, 2023 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-37262161

RESUMO

The rich diversity of morphology and behavior displayed across primate species provides an informative context in which to study the impact of genomic diversity on fundamental biological processes. Analysis of that diversity provides insight into long-standing questions in evolutionary and conservation biology and is urgent given severe threats these species are facing. Here, we present high-coverage whole-genome data from 233 primate species representing 86% of genera and all 16 families. This dataset was used, together with fossil calibration, to create a nuclear DNA phylogeny and to reassess evolutionary divergence times among primate clades. We found within-species genetic diversity across families and geographic regions to be associated with climate and sociality, but not with extinction risk. Furthermore, mutation rates differ across species, potentially influenced by effective population sizes. Lastly, we identified extensive recurrence of missense mutations previously thought to be human specific. This study will open a wide range of research avenues for future primate genomic research.


Assuntos
Evolução Biológica , Variação Genética , Primatas , Animais , Humanos , Genoma , Taxa de Mutação , Filogenia , Primatas/genética , Densidade Demográfica
4.
Science ; 380(6648): eabn8153, 2023 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-37262156

RESUMO

Personalized genome sequencing has revealed millions of genetic differences between individuals, but our understanding of their clinical relevance remains largely incomplete. To systematically decipher the effects of human genetic variants, we obtained whole-genome sequencing data for 809 individuals from 233 primate species and identified 4.3 million common protein-altering variants with orthologs in humans. We show that these variants can be inferred to have nondeleterious effects in humans based on their presence at high allele frequencies in other primate populations. We use this resource to classify 6% of all possible human protein-altering variants as likely benign and impute the pathogenicity of the remaining 94% of variants with deep learning, achieving state-of-the-art accuracy for diagnosing pathogenic variants in patients with genetic diseases.


Assuntos
Variação Genética , Primatas , Animais , Humanos , Sequência de Bases , Frequência do Gene , Primatas/genética , Sequenciamento Completo do Genoma
5.
bioRxiv ; 2023 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-37205491

RESUMO

Personalized genome sequencing has revealed millions of genetic differences between individuals, but our understanding of their clinical relevance remains largely incomplete. To systematically decipher the effects of human genetic variants, we obtained whole genome sequencing data for 809 individuals from 233 primate species, and identified 4.3 million common protein-altering variants with orthologs in human. We show that these variants can be inferred to have non-deleterious effects in human based on their presence at high allele frequencies in other primate populations. We use this resource to classify 6% of all possible human protein-altering variants as likely benign and impute the pathogenicity of the remaining 94% of variants with deep learning, achieving state-of-the-art accuracy for diagnosing pathogenic variants in patients with genetic diseases. One Sentence Summary: Deep learning classifier trained on 4.3 million common primate missense variants predicts variant pathogenicity in humans.

6.
J Hum Evol ; 174: 103293, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36493598

RESUMO

There have been multiple published phylogenetic analyses of platyrrhine primates (New World monkeys) using both morphological and molecular data, but relatively few that have integrated both types of data into a total evidence approach. Here, we present phylogenetic analyses of recent and fossil platyrrhines, based on a total evidence data set of 418 morphological characters and 10.2 kilobases of DNA sequence data from 17 nuclear genes taken from previous studies, using undated and tip-dating approaches in a Bayesian framework. We compare the results of these analyses with molecular scaffold analyses using maximum parsimony and Bayesian approaches, and we use a formal information theoretic approach to identify unstable taxa. After a posteriori pruning of unstable taxa, the undated and tip-dating topologies appear congruent with recent molecular analyses and support largely similar relationships, with strong support for Stirtonia as a stem alouattine, Neosaimiri as a stem saimirine, Cebupithecia as a stem pitheciine, and Lagonimico as a stem callitrichid. Both analyses find three Greater Antillean subfossil platyrrhines (Xenothrix, Antillothrix, and Paralouatta) to form a clade that is related to Callicebus, congruent with a single dispersal event by the ancestor of this clade to the Greater Antilles. They also suggest that the fossil Proteropithecia may not be closely related to pitheciines, and that all known platyrrhines older than the Middle Miocene are stem taxa. Notably, the undated analysis found the Early Miocene Panamacebus (currently recognized as the oldest known cebid) to be unstable, and the tip-dating analysis placed it outside crown Platyrrhini. Our tip-dating analysis supports a late Oligocene or earliest Miocene (20.8-27.0 Ma) age for crown Platyrrhini, congruent with recent molecular clock analyses.


Assuntos
Evolução Biológica , Pitheciidae , Animais , Filogenia , Teorema de Bayes , Platirrinos/anatomia & histologia , Fósseis
7.
Mol Ecol ; 31(14): 3888-3902, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35638312

RESUMO

Mitochondrial DNA remains a cornerstone for molecular ecology, especially for study species from which high-quality tissue samples cannot be easily obtained. Methods using mitochondrial markers are usually reliant on reference databases, but these are often incomplete. Furthermore, available mitochondrial genomes often lack crucial metadata, such as sampling location, limiting their utility for many analyses. Here, we assembled 205 new mitochondrial genomes for platyrrhine primates, most from the Amazon and with known sampling locations. We present a dated mitogenomic phylogeny based on these samples along with additional published platyrrhine mitogenomes, and use this to assess support for the long-standing riverine barrier hypothesis (RBH), which proposes that river formation was a major driver of speciation in Amazonian primates. Along the Amazon, Negro, and Madeira rivers, we found mixed support for the RBH. While we identified divergences that coincide with a river barrier, only some occur synchronously and also overlap with the proposed dates of river formation. The most compelling evidence is for the Amazon river potentially driving speciation within bearded saki monkeys (Chiropotes spp.) and within the smallest extant platyrrhines, the marmosets and tamarins. However, we also found that even large rivers do not appear to be barriers for some primates, including howler monkeys (Alouatta spp.), uakaris (Cacajao spp.), sakis (Pithecia spp.), and robust capuchins (Sapajus spp.). Our results support a more nuanced, clade-specific effect of riverine barriers and suggest that other evolutionary mechanisms, besides the RBH and allopatric speciation, may have played an important role in the diversification of platyrrhines.


Assuntos
Genoma Mitocondrial , Rios , Animais , Evolução Biológica , Genoma Mitocondrial/genética , Filogenia , Primatas
8.
Microb Biotechnol ; 15(5): 1574-1585, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-34927803

RESUMO

The development and advent of mutagenesis tools for solventogenic clostridial species in recent years has allowed for the increased refinement of industrially relevant strains. In this study we have utilised CLEAVE™, a CRISPR/Cas genome editing system developed by Green Biologics Ltd., to engineer a strain of Clostridium saccharoperbutylacetonicum N1-4(HMT) with potentially useful solvents titres and energy metabolism. As one of two enzymes responsible for the conversion of glyceraldehyde-3-phosphate (GAP) to 3-phosphoglyceric acid in glycolysis, it was hypothesised that deletion of gapN would increase ATP and NADH production that could in turn improve solvent production. Herein, whole genome sequencing has been used to evaluate CLEAVE™ and the successful knockout of gapN, demonstrating a clean knockout with no other detectable variations from the wild type sequence. Elevated solvent levels were detected during the first 24 h of batch fermentation, indicating an earlier shift to solventogenesis. A 2.4-fold increase in ATP concentration was observed, and quantitation of NAD(P)H derivatives revealed a more reducing cytoplasm for the gapN strain. These findings expand our understanding of clostridium carbon metabolism and report a new approach to optimising biofuel production.


Assuntos
Clostridium , Gliceraldeído-3-Fosfato Desidrogenases , Trifosfato de Adenosina/metabolismo , Clostridium/genética , Clostridium/metabolismo , Gliceraldeído-3-Fosfato Desidrogenases/metabolismo , Solventes/metabolismo
9.
Proc Biol Sci ; 288(1957): 20210552, 2021 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-34403636

RESUMO

Interactions between hosts and their resident microbial communities are a fundamental component of fitness for both agents. Though recent research has highlighted the importance of interactions between animals and their bacterial communities, comparative evidence for fungi is lacking, especially in natural populations. Using data from 49 species, we present novel evidence of strong covariation between fungal and bacterial communities across the host phylogeny, indicative of recruitment by hosts for specific suites of microbes. Using co-occurrence networks, we demonstrate marked variation across host taxonomy in patterns of covariation between bacterial and fungal abundances. Host phylogeny drives differences in the overall richness of bacterial and fungal communities, but the effect of diet on richness was only evident in the mammalian gut microbiome. Sample type, tissue storage and DNA extraction method also affected bacterial and fungal community composition, and future studies would benefit from standardized approaches to sample processing. Collectively these data indicate fungal microbiomes may play a key role in host fitness and suggest an urgent need to study multiple agents of the animal microbiome to accurately determine the strength and ecological significance of host-microbe interactions.


Assuntos
Microbiota , Micobioma , Animais , Bactérias/genética , Interações entre Hospedeiro e Microrganismos , Filogenia
10.
Microbiology (Reading) ; 167(5)2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-34032566

RESUMO

Tackling antimicrobial resistance (AMR) is particularly challenging in low-resource settings such as Fort Portal Regional Referral Hospital (FPRRH) in Western Uganda. Specific knowledge of local AMR epidemiology is required to inform evidence-based improvement of antibiotic stewardship measures in the hospital. To address this, we combined existing antimicrobial susceptibility testing (AST) from FPRRH, with whole genome sequencing (WGS) of 41 Staphylococcus aureus isolates (2017-2019). AST revealed 73 % (30 of 41) of isolates were resistant to one or more antibiotics and 29 % (12 of 41) were multi-drug resistant (MDR). Resistance phenotypes were largely explained by the presence of antibiotic resistance genes in WGS data. Five isolates were methicillin-resistant S. aureus (MRSA) and MDR. Although all isolates were susceptible to clindamycin, a 24 % carriage of erm genes suggests potential for rapid development of resistance. We inferred a population structure for the S. aureus isolates by comparing their core genomes. Twenty isolates formed a tight cluster corresponding to multilocus sequence typing clonal complex (CC) 152, a CC found to be particularly prevalent in northern Africa. The frequency of genes associated with methicillin, chloramphenicol and ciprofloxacin resistance were significantly lower among CC152 strains than non-CC152 strains; thus, in keeping with previous work, we find that CC152 is almost exclusively methicillin-sensitive S. aureus (MSSA). Also, in agreement with other studies, we observed that the occurrence of Panton-Valentine leukocidin toxin-encoding genes was significantly higher among CC152 strains than non-CC152 strains. However, we also observed that the coagulase gene was over-represented in this CC, further defining the virulence strategy of this important pathogen. By generating detailed information about the epidemiology of circulating S. aureus and their antibiotic susceptibility, our study has provided, for the first time, data on which evidence-based infection and AMR interventions at FPRRH can be based.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Genoma Bacteriano , Humanos , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Encaminhamento e Consulta/estatística & dados numéricos , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/genética , Staphylococcus aureus/metabolismo , Uganda , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
11.
Arch Microbiol ; 203(5): 2541-2550, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33682076

RESUMO

The spread of multidrug-resistance in Gram-negative bacterial pathogens presents a major clinical challenge, and new approaches are required to combat these organisms. Nitric oxide (NO) is a well-known antimicrobial that is produced by the immune system in response to infection, and numerous studies have demonstrated that NO is a respiratory inhibitor with both bacteriostatic and bactericidal properties. However, given that loss of aerobic respiratory complexes is known to diminish antibiotic efficacy, it was hypothesised that the potent respiratory inhibitor NO would elicit similar effects. Indeed, the current work demonstrates that pre-exposure to NO-releasers elicits a > tenfold increase in IC50 for gentamicin against pathogenic E. coli (i.e. a huge decrease in lethality). It was therefore hypothesised that hyper-sensitivity to NO may have arisen in bacterial pathogens and that this trait could promote the acquisition of antibiotic-resistance mechanisms through enabling cells to persist in the presence of toxic levels of antibiotic. To test this hypothesis, genomics and microbiological approaches were used to screen a collection of E. coli clinical isolates for antibiotic susceptibility and NO tolerance, although the data did not support a correlation between increased carriage of antibiotic resistance genes and NO tolerance. However, the current work has important implications for how antibiotic susceptibility might be measured in future (i.e. ± NO) and underlines the evolutionary advantage for bacterial pathogens to maintain tolerance to toxic levels of NO.


Assuntos
Aminoglicosídeos/farmacologia , Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Escherichia coli/efeitos dos fármacos , Óxido Nítrico/farmacologia , Evolução Biológica , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Gentamicinas/farmacologia , Humanos , Testes de Sensibilidade Microbiana
12.
Food Res Int ; 141: 110035, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33641956

RESUMO

Seafood represents up to 20% of animal protein consumption in global food consumption and is a critical dietary and income resource for the world's population. Currently, over 30% of marine fish stocks are harvested at unsustainable levels, and the industry faces challenges related to Illegal, Unregulated and Unreported (IUU) fishing. Accurate species identification is one critical component of successful stock management and helps combat fraud. Existing DNA-based technologies permit identification of seafood even when morphological features are removed, but are either too time-consuming, too expensive, or too specific for widespread use throughout the seafood supply chain. FASTFISH-ID is an innovative commercial platform for fish species authentication, employing closed-tube barcoding in a portable device. This method begins with asymmetric PCR amplification of the full length DNA barcode sequence and subsequently interrogates the resulting single-stranded DNA with a universal set of Positive/Negative probes labeled in two fluorescent colors. Each closed-tube reaction generates two species-specific fluorescent signatures that are then compared to a cloud-based library of previously validated fluorescent signatures. This novel approach results in rapid, automated species authentication without the need for complex, time consuming, identification by DNA sequencing, or repeated analysis with a panel of species-specific tests. Performance of the FASTFISH-ID platform was assessed in a blinded study carried out in three laboratories located in the UK and North America. The method exhibited a 98% success rate among the participating laboratories when compared to species identification via conventional DNA barcoding by sequencing. Thus, FASTFISH-ID is a promising new platform for combating seafood fraud across the global seafood supply chain.


Assuntos
Código de Barras de DNA Taxonômico , DNA , Animais , DNA/genética , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Especificidade da Espécie
13.
Microb Genom ; 6(1)2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31922467

RESUMO

The majority of bacterial genomes have high coding efficiencies, but there are some genomes of intracellular bacteria that have low gene density. The genome of the endosymbiont Sodalis glossinidius contains almost 50 % pseudogenes containing mutations that putatively silence them at the genomic level. We have applied multiple 'omic' strategies, combining Illumina and Pacific Biosciences Single-Molecule Real-Time DNA sequencing and annotation, stranded RNA sequencing and proteome analysis to better understand the transcriptional and translational landscape of Sodalis pseudogenes, and potential mechanisms for their control. Between 53 and 74 % of the Sodalis transcriptome remains active in cell-free culture. The mean sense transcription from coding domain sequences (CDSs) is four times greater than that from pseudogenes. Comparative genomic analysis of six Illumina-sequenced Sodalis isolates from different host Glossina species shows pseudogenes make up ~40 % of the 2729 genes in the core genome, suggesting that they are stable and/or that Sodalis is a recent introduction across the genus Glossina as a facultative symbiont. These data shed further light on the importance of transcriptional and translational control in deciphering host-microbe interactions. The combination of genomics, transcriptomics and proteomics gives a multidimensional perspective for studying prokaryotic genomes with a view to elucidating evolutionary adaptation to novel environmental niches.


Assuntos
Enterobacteriaceae/genética , Genes Bacterianos , Pseudogenes , Animais , Proteínas de Bactérias/genética , Proteoma , Análise de Sequência de DNA , Análise de Sequência de RNA , Simbiose , Transcriptoma , Moscas Tsé-Tsé/microbiologia
14.
Genome Biol Evol ; 12(2): 3778-3791, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31830246

RESUMO

The olive fruit fly Bactrocera oleae is a major pest of olives worldwide and houses a specialized gut microbiota dominated by the obligate symbiont "Candidatus Erwinia dacicola." Candidatus Erwinia dacicola is thought to supplement dietary nitrogen to the host, with only indirect evidence for this hypothesis so far. Here, we sought to investigate the contribution of the symbiosis to insect fitness and explore the ecology of the insect gut. For this purpose, we examined the composition of bacterial communities associated with Cretan olive fruit fly populations, and inspected several genomes and one transcriptome assembly. We identified, and reconstructed the genome of, a novel component of the gut microbiota, Tatumella sp. TA1, which is stably associated with Mediterranean olive fruit fly populations. We also reconstructed a number of pathways related to nitrogen assimilation and interactions with the host. The results show that, despite variation in taxa composition of the gut microbial community, core functions related to the symbiosis are maintained. Functional redundancy between different microbial taxa was observed for genes involved in urea hydrolysis. The latter is encoded in the obligate symbiont genome by a conserved urease operon, likely acquired by horizontal gene transfer, based on phylogenetic evidence. A potential underlying mechanism is the action of mobile elements, especially abundant in the Ca. E. dacicola genome. This finding, along with the identification, in the studied genomes, of extracellular surface structure components that may mediate interactions within the gut community, suggest that ongoing and past genetic exchanges between microbes may have shaped the symbiosis.


Assuntos
Microbioma Gastrointestinal/fisiologia , Olea/parasitologia , Simbiose/fisiologia , Tephritidae/metabolismo , Tephritidae/microbiologia , Animais , Microbioma Gastrointestinal/genética , Transferência Genética Horizontal , Genômica/métodos , Simbiose/genética , Tephritidae/genética , Urease/genética , Urease/metabolismo
15.
Nat Commun ; 9(1): 2635, 2018 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-29980663

RESUMO

Pseudomonas aeruginosa colonises the upper airway of cystic fibrosis (CF) patients, providing a reservoir of host-adapted genotypes that subsequently establish chronic lung infection. We previously experimentally-evolved P. aeruginosa in a murine model of respiratory tract infection and observed early-acquired mutations in pmrB, encoding the sensor kinase of a two-component system that promoted establishment and persistence of infection. Here, using proteomics, we show downregulation of proteins involved in LPS biosynthesis, antimicrobial resistance and phenazine production in pmrB mutants, and upregulation of proteins involved in adherence, lysozyme resistance and inhibition of the chloride ion channel CFTR, relative to wild-type strain LESB65. Accordingly, pmrB mutants are susceptible to antibiotic treatment but show enhanced adherence to airway epithelial cells, resistance to lysozyme treatment, and downregulate host CFTR expression. We propose that P. aeruginosa pmrB mutations in CF patients are subject to an evolutionary trade-off, leading to enhanced colonisation potential, CFTR inhibition, and resistance to host defences, but also to increased susceptibility to antibiotics.


Assuntos
Adaptação Fisiológica , Proteínas de Bactérias/metabolismo , Evolução Biológica , Interações Hospedeiro-Patógeno , Pseudomonas aeruginosa/metabolismo , Fatores de Transcrição/metabolismo , Células A549 , Adaptação Fisiológica/efeitos dos fármacos , Animais , Anti-Infecciosos/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Contagem de Colônia Microbiana , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Regulação para Baixo , Células Epiteliais/metabolismo , Fímbrias Bacterianas/efeitos dos fármacos , Fímbrias Bacterianas/metabolismo , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Humanos , Pulmão/microbiologia , Pulmão/patologia , Camundongos , Testes de Sensibilidade Microbiana , Modelos Biológicos , Movimento , Muramidase/metabolismo , Mutação/genética , Análise de Componente Principal , Proteômica , Infecções por Pseudomonas/microbiologia , Infecções por Pseudomonas/patologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/isolamento & purificação
16.
PLoS One ; 12(11): e0188936, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29190673

RESUMO

BACKGROUND: Water serves as a potential reservoir for Campylobacter, the leading cause of bacterial gastroenteritis in humans. However, little is understood about the mechanisms underlying variations in survival characteristics between different strains of C. jejuni in natural environments, including water. RESULTS: We identified three Campylobacter jejuni strains that exhibited variability in their ability to retain culturability after suspension in tap water at two different temperatures (4°C and 25°C). Of the three, strains C. jejuni M1 exhibited the most rapid loss of culturability whilst retaining viability. Using RNAseq transcriptomics, we characterised C. jejuni M1 gene expression in response to suspension in water by analyzing bacterial suspensions recovered immediately after introduction into water (Time 0), and from two sampling time/temperature combinations where considerable loss of culturability was evident, namely (i) after 24 h at 25°C, and (ii) after 72 h at 4°C. Transcript data were compared with a culture-grown control. Some gene expression characteristics were shared amongst the three populations recovered from water, with more genes being up-regulated than down. Many of the up-regulated genes were identified in the Time 0 sample, whereas the majority of down-regulated genes occurred in the 25°C (24 h) sample. CONCLUSIONS: Variations in expression were found amongst genes associated with oxygen tolerance, starvation and osmotic stress. However, we also found upregulation of flagellar assembly genes, accompanied by down-regulation of genes involved in chemotaxis. Our data also suggested a switch from secretion via the sec system to via the tat system, and that the quorum sensing gene luxS may be implicated in the survival of strain M1 in water. Variations in gene expression also occurred in accessory genome regions. Our data suggest that despite the loss of culturability, C. jejuni M1 remains viable and adapts via specific changes in gene expression.


Assuntos
Campylobacter jejuni/genética , Genes Bacterianos , Transcriptoma , Campylobacter jejuni/patogenicidade , Campylobacter jejuni/fisiologia , Transporte de Elétrons , Regulação Bacteriana da Expressão Gênica , Pressão Osmótica , Estresse Oxidativo , Percepção de Quorum , Análise de Sequência de RNA , Temperatura , Virulência/genética , Microbiologia da Água
17.
FEMS Microbiol Ecol ; 93(5)2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28379446

RESUMO

Microbial ecology provides insights into the ecological and evolutionary dynamics of microbial communities underpinning every ecosystem on Earth. Microbial communities can now be investigated in unprecedented detail, although there is still a wealth of open questions to be tackled. Here we identify 50 research questions of fundamental importance to the science or application of microbial ecology, with the intention of summarising the field and bringing focus to new research avenues. Questions are categorised into seven themes: host-microbiome interactions; health and infectious diseases; human health and food security; microbial ecology in a changing world; environmental processes; functional diversity; and evolutionary processes. Many questions recognise that microbes provide an extraordinary array of functional diversity that can be harnessed to solve real-world problems. Our limited knowledge of spatial and temporal variation in microbial diversity and function is also reflected, as is the need to integrate micro- and macro-ecological concepts, and knowledge derived from studies with humans and other diverse organisms. Although not exhaustive, the questions presented are intended to stimulate discussion and provide focus for researchers, funders and policy makers, informing the future research agenda in microbial ecology.


Assuntos
Bactérias/crescimento & desenvolvimento , Evolução Biológica , Doenças Transmissíveis , Ecossistema , Inocuidade dos Alimentos , Microbiota , Ecologia , Humanos
18.
PLoS Negl Trop Dis ; 9(8): e0003933, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26273826

RESUMO

BACKGROUND: Differentiation of one life-cycle stage to the next is critical for survival and transmission of apicomplexan parasites. A number of studies have shown that stage differentiation is a stochastic process and is associated with a point that commits the cell to a change over in the pattern of gene expression. Studies on differentiation to merozoite production (merogony) in T. annulata postulated that commitment involves a concentration threshold of DNA binding proteins and an auto-regulatory loop. PRINCIPAL FINDINGS: In this study ApiAP2 DNA binding proteins that show changes in expression level during merogony of T. annulata have been identified. DNA motifs bound by orthologous domains in Plasmodium were found to be enriched in upstream regions of stage-regulated T. annulata genes and validated as targets for the T. annulata AP2 domains by electrophoretic mobility shift assay (EMSA). Two findings were of particular note: the gene in T. annulata encoding the orthologue of the ApiAP2 domain in the AP2-G factor that commits Plasmodium to gametocyte production, has an expression profile indicating involvement in transmission of T. annulata to the tick vector; genes encoding related domains that bind, or are predicted to bind, sequence motifs of the type 5'-(A)CACAC(A) are implicated in differential regulation of gene expression, with one gene (TA11145) likely to be preferentially up-regulated via auto-regulation as the cell progresses to merogony. CONCLUSIONS: We postulate that the Theileria factor possessing the AP2 domain orthologous to that of Plasmodium AP2-G may regulate gametocytogenesis in a similar manner to AP2-G. In addition, paralogous ApiAP2 factors that recognise 5'-(A)CACAC(A) type motifs could operate in a competitive manner to promote reversible progression towards the point that commits the cell to undergo merogony. Factors possessing AP2 domains that bind (or are predicted to bind) this motif are present in the vector-borne genera Theileria, Babesia and Plasmodium, and other Apicomplexa; leading to the proposal that the mechanisms that control stage differentiation will show a degree of conservation.


Assuntos
Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica no Desenvolvimento , Merozoítos/crescimento & desenvolvimento , Proteínas de Protozoários/genética , Theileria annulata/genética , Proteínas de Ligação a DNA/metabolismo , Merozoítos/metabolismo , Proteínas de Protozoários/metabolismo , Theileria annulata/crescimento & desenvolvimento , Theileria annulata/metabolismo
19.
BMC Genomics ; 16: 642, 2015 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-26311067

RESUMO

BACKGROUND: Almost all genome sequencing projects neglect the fact that diploid organisms contain two genome copies and consequently what is published is a composite of the two. This means that the relationship between alternate alleles at two or more linked loci is lost. We have developed a simplified method of directly obtaining the haploid sequences of each genome copy from an individual organism. RESULTS: The diploid sequences of three groups of cattle samples were obtained using a simple sample preparation procedure requiring only a microscope and a haemocytometer. Samples were: 1) lymphocytes from a single Angus steer; 2) sperm cells from an Angus bull; 3) lymphocytes from East African Zebu (EAZ) cattle collected and processed in a field laboratory in Eastern Kenya. Haploid sequence from a fosmid library prepared from lymphocytes of an EAZ cow was used for comparison. Cells were serially diluted to a concentration of one cell per microlitre by counting with a haemocytometer at each dilution. One microlitre samples, each potentially containing a single cell, were lysed and divided into six aliquots (except for the sperm samples which were not divided into aliquots). Each aliquot was amplified with phi29 polymerase and sequenced. Contigs were obtained by mapping to the bovine UMD3.1 reference genome assembly and scaffolds were assembled by joining adjacent contigs that were within a threshold distance of each other. Scaffolds that appeared to contain artefacts of CNV or repeats were filtered out leaving scaffolds with an N50 length of 27-133 kb and a 88-98 % genome coverage. SNP haplotypes were assembled with the Single Individual Haplotyper program to generate an N50 size of 97-201 kb but only ~27-68 % genome coverage. This method can be used in any laboratory with no special equipment at only slightly higher costs than conventional diploid genome sequencing. A substantial body of software for analysis and workflow management was written and is available as supplementary data. CONCLUSIONS: We have developed a set of laboratory protocols and software tools that will enable any laboratory to obtain haplotype sequences at only modestly greater cost than traditional mixed diploid sequences.


Assuntos
Diploide , Genoma , Genômica , Haplótipos , Análise de Sequência de DNA , Biologia Computacional/métodos , Genômica/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Reprodutibilidade dos Testes , Análise de Sequência de DNA/métodos , Análise de Célula Única , Software
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