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"Cockburn, April"
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Complete Genome Sequence of the Cystic Fibrosis Pathogen Achromobacter xylosoxidans NH44784-1996 Complies with Important Pathogenic Phenotypes
by
Høiby, Niels
,
Kühl, Michael
,
Bjarnsholt, Thomas
in
Acetylcholine receptors
,
Achromobacter
,
Achromobacter denitrificans - drug effects
2013
Achromobacter xylosoxidans is an environmental opportunistic pathogen, which infects an increasing number of immunocompromised patients. In this study we combined genomic analysis of a clinical isolated A. xylosoxidans strain with phenotypic investigations of its important pathogenic features. We present a complete assembly of the genome of A. xylosoxidans NH44784-1996, an isolate from a cystic fibrosis patient obtained in 1996. The genome of A. xylosoxidans NH44784-1996 contains approximately 7 million base pairs with 6390 potential protein-coding sequences. We identified several features that render it an opportunistic human pathogen, We found genes involved in anaerobic growth and the pgaABCD operon encoding the biofilm adhesin poly-β-1,6-N-acetyl-D-glucosamin. Furthermore, the genome contains a range of antibiotic resistance genes coding efflux pump systems and antibiotic modifying enzymes. In vitro studies of A. xylosoxidans NH44784-1996 confirmed the genomic evidence for its ability to form biofilms, anaerobic growth via denitrification, and resistance to a broad range of antibiotics. Our investigation enables further studies of the functionality of important identified genes contributing to the pathogenicity of A. xylosoxidans and thereby improves our understanding and ability to treat this emerging pathogen.
Journal Article
Effects of sheared chromatin length on ChIP-seq quality and sensitivity
2021
Chromatin immunoprecipitation followed by massively parallel, high throughput sequencing (ChIP-seq) is the method of choice for genome-wide identification of DNA segments bound by specific transcription factors or in chromatin with particular histone modifications. However, the quality of ChIP-seq datasets varies widely, with a substantial fraction being of intermediate to poor quality. Thus, it is important to discern and control the factors that contribute to variation in ChIP-seq. In this study, we focused on sonication, a user-controlled variable, to produce sheared chromatin. We systematically varied the amount of shearing of fixed chromatin from a mouse erythroid cell line, carefully measuring the distribution of resultant fragment lengths prior to ChIP-seq. This systematic study was complemented with a retrospective analysis of additional experiments. We found that the level of sonication had a pronounced impact on the quality of ChIP-seq signals. Over-sonication consistently reduced quality, while the impact of under-sonication differed among transcription factors, with no impact on sites bound by CTCF but frequently leading to the loss of sites occupied by TAL1 or bound by POL2. The bound sites not observed in low-quality datasets were inferred to be a mix of both direct and indirect binding. We leveraged these findings to produce a set of CTCF ChIP-seq datasets in rare, primary hematopoietic progenitor cells. Our observation that the amount of chromatin sonication is a key variable in success of ChIP-seq experiments indicates that monitoring the level of sonication can improve ChIP-seq quality and reproducibility and facilitate ChIP-seq in rare cell types.
Journal Article
Interspecies regulatory landscapes and elements revealed by novel joint systematic integration of human and mouse blood cell epigenomes
2024
Knowledge of locations and activities of cis-regulatory elements (CREs) is needed to decipher basic mechanisms of gene regulation and to understand the impact of genetic variants on complex traits. Previous studies identified candidate CREs (cCREs) using epigenetic features in one species, making comparisons difficult between species. In contrast, we conducted an interspecies study defining epigenetic states and identifying cCREs in blood cell types to generate regulatory maps that are comparable between species, using integrative modeling of eight epigenetic features jointly in human and mouse in our Validated Systematic Integration (VISION) Project. The resulting catalogs of cCREs are useful resources for further studies of gene regulation in blood cells, indicated by high overlap with known functional elements and strong enrichment for human genetic variants associated with blood cell phenotypes. The contribution of each epigenetic state in cCREs to gene regulation, inferred from a multivariate regression, was used to estimate epigenetic state Regulatory Potential (esRP) scores for each cCRE in each cell type, which were used to categorize dynamic changes in cCREs. Groups of cCREs displaying similar patterns of regulatory activity in human and mouse cell types, obtained by joint clustering on esRP scores, harbored distinctive transcription factor binding motifs that were similar between species. An interspecies comparison of cCREs revealed both conserved and species-specific patterns of epigenetic evolution. Finally, we showed that comparisons of the epigenetic landscape between species can reveal elements with similar roles in regulation, even in the absence of genomic sequence alignment.
Journal Article
An integrative view of the regulatory and transcriptional landscapes in mouse hematopoiesis
2020
Thousands of epigenomic datasets have been generated in the past decade, but it is difficult for researchers to effectively utilize all the data relevant to their projects. Systematic integrative analysis can help meet this need, and the VISION project was established for ValIdated Systematic IntegratiON of epigenomic data in hematopoiesis. Here, we systematically integrated extensive data recording epigenetic features and transcriptomes from many sources, including individual laboratories and consortia, to produce a comprehensive view of the regulatory landscape of differentiating hematopoietic cell types in mouse. By employing IDEAS as our Integrative and Discriminative Epigenome Annotation System, we identified and assigned epigenetic states simultaneously along chromosomes and across cell types, precisely and comprehensively. Combining nuclease accessibility and epigenetic states produced a set of over 200,000 candidate cis-regulatory elements (cCREs) that efficiently capture enhancers and promoters. The transitions in epigenetic states of these cCREs across cell types provided insights into mechanisms of regulation, including decreases in numbers of active cCREs during differentiation of most lineages, transitions from poised to active or inactive states, and shifts in nuclease accessibility of CTCF-bound elements. Regression modeling of epigenetic states at cCREs and gene expression produced a versatile resource to improve selection of cCREs potentially regulating target genes. These resources are available from our VISION website (usevision.org) to aid research in genomics and hematopoiesis. Footnotes * Major changes in the revised version were: (1) substantially shorter main text (2) further study of sites where CTCF is retained but chromatin accessibility is lost during cell differentiation (2) much material was moved to Supplemental Materials (3) Supplemental Materials was re-organized. * http://usevision.org
Police lay charges in pit bull attack as Ontario bans breed
The charges and the new province-wide ban come only five days after three people, including 21/2-year-old Jayden Clairoux, were injured by three pit bull-type dogs in a Pinecrest-area neighbourhood. City officials say the same three dogs attacked two boys in January. Pit bull defenders vowed to go to court to challenge the ban on constitutional grounds. \"We have raised more than $40,000 and we are raising more as well\" to finance the court action, said Julie King, political action director for the Staffordshire Bull Terrier Club of Canada. The club has joined other defenders of the breed in retaining high-profile Toronto lawyer Clayton Ruby. He has suggested the law could be challenged because, among other things, it does not clearly define a pit bull. Fans of the pit bull have argued that a breed-specific ban won't deter irresponsible owners who will simply migrate to from breed to breed if they want a vicious dog. The ban didn't please Canada Safety Council president Emile Therien, who said outlawing dogs based on their breed is a \"slippery slope.\" Mr. Therien was happy that police had laid criminal charges in Jayden's case, noting that there is precedent for such charges against the owners of dogs that maul or bite.
Newspaper Article
Human Papillomavirus Prevalence in Invasive Laryngeal Cancer in the United States
2014
Human papillomavirus (HPV) is a major risk factor for specific cancers of the head and neck, particularly malignancies of the tonsil and base of the tongue. However, the role of HPV in the development of laryngeal cancer has not been definitively established. We conducted a population-based, cancer registry study to evaluate and characterize the genotype-specific prevalence of HPV in invasive laryngeal cancer cases diagnosed in the U.S.
The presence of genotype-specific HPV DNA was evaluated using the Linear Array HPV Genotyping Test and the INNO-LiPA HPV Genotyping Assay in formalin-fixed paraffin embedded tissue from 148 invasive laryngeal cancer cases diagnosed in 1993-2004 within the catchment area of three U.S. SEER cancer registries.
HPV DNA was detected in 31 of 148 (21%) invasive laryngeal cancers. Thirteen different genotypes were detected. Overall, HPV 16 and HPV 33 were the most commonly detected types. HPV was detected in 33% (9/27) of women compared with 18% (22/121) of men (p = 0.08). After adjustment for age and year of diagnosis, female patients were more likely to have HPV-positive laryngeal tumors compared to males (adjusted OR 2.84, 95% CI 1.07-7.51). Viral genotype differences were also observed between the sexes. While HPV 16 and 18 constituted half of HPV-positive cases occurring in men, among women, only 1 was HPV 16 positive and none were positive for HPV 18. Overall 5-year survival did not vary by HPV status.
HPV may be involved in the development of a subset of laryngeal cancers and its role may be more predominant in women compared to men.
Journal Article