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  • 1
    Language: English
    In: Journal of bacteriology, 01 August 2016, Vol.198(15), pp.2131-9
    Description: Intracellular bacterial pathogens in the family Chlamydiaceae are causes of human blindness, sexually transmitted disease, and pneumonia. Genetic dissection of the mechanisms of chlamydial pathogenicity has been hindered by multiple limitations, including the inability to inactivate genes that would prevent the production of elementary bodies. Many genes are also Chlamydia-specific genes, and chlamydial genomes have undergone extensive reductive evolution, so functions often cannot be inferred from homologs in other organisms. Conditional mutants have been used to study essential genes of many microorganisms, so we screened a library of 4,184 ethyl methanesulfonate-mutagenized Chlamydia trachomatis isolates for temperature-sensitive (TS) mutants that developed normally at physiological temperature (37°C) but not at nonphysiological temperatures. Heat-sensitive TS mutants were identified at a high frequency, while cold-sensitive mutants were less common. Twelve TS mutants were mapped using a novel markerless recombination approach, PCR, and genome sequencing. TS alleles of genes that play essential roles in other bacteria and chlamydia-specific open reading frames (ORFs) of unknown function were identified. Temperature-shift assays determined that phenotypes of the mutants manifested at distinct points in the developmental cycle. Genome sequencing of a larger population of TS mutants also revealed that the screen had not reached saturation. In summary, we describe the first approach for studying essential chlamydial genes and broadly applicable strategies for genetic mapping in Chlamydia spp. and mutants that both define checkpoints and provide insights into the biology of the chlamydial developmental cycle. Study of the pathogenesis of Chlamydia spp. has historically been hampered by a lack of genetic tools. Although there has been recent progress in chlamydial genetics, the existing approaches have limitations for the study of the genes that mediate growth of these organisms in cell culture. We used a genetic screen to identify conditional Chlamydia mutants and then mapped these alleles using a broadly applicable recombination strategy. Phenotypes of the mutants provide fundamental insights into unexplored areas of chlamydial pathogenesis and intracellular biology. Finally, the reagents and approaches we describe are powerful resources for the investigation of these organisms.
    Keywords: Recombination, Genetic ; Temperature ; Chlamydia Trachomatis -- Physiology
    ISSN: 00219193
    E-ISSN: 1098-5530
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  • 2
    Language: English
    In: American journal of respiratory and critical care medicine, 15 July 2016, Vol.194(2), pp.226-35
    Description: Previous work found the lung microbiome in healthy subjects infected with HIV was similar to that in uninfected subjects. We hypothesized the lung microbiome from subjects infected with HIV with more advanced disease would differ from that of an uninfected control population. To measure the lung microbiome in an HIV-infected population with advanced disease. 16s RNA gene sequencing was performed on acellular bronchoalveolar lavage (BAL) fluid from 30 subjects infected with HIV with advanced disease (baseline mean CD4 count, 262 cells/mm(3)) before and up to 3 years after starting highly active antiretroviral therapy (HAART) and compared with 22 uninfected control subjects. The lung microbiome in subjects infected with HIV with advanced disease demonstrated decreased alpha diversity (richness and diversity) and greater beta diversity compared with uninfected BAL. Differences improved with HAART, but still persisted up to 3 years after starting therapy. Population dispersion in the group infected with HIV was significantly greater than in the uninfected cohort and declined after treatment. There were differences in the relative abundance of some bacteria between the two groups at baseline and after 1 year of therapy. After 1 year on HAART, HIV BAL contained an increased abundance of Prevotella and Veillonella, bacteria previously associated with lung inflammation. The lung microbiome in subjects infected with HIV with advanced disease is altered compared with an uninfected population both in diversity and bacterial composition. Differences remain up to 3 years after starting HAART. We speculate an altered lung microbiome in HIV infection may contribute to chronic inflammation and lung complications seen in the HAART era.
    Keywords: HIV Infection ; Advanced Disease ; Lung Microbiome ; Microbial Diversity ; Microbiota ; HIV Infections -- Microbiology ; Lung -- Microbiology
    ISSN: 1073449X
    E-ISSN: 1535-4970
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  • 3
    Language: English
    In: BMC microbiology, 11 August 2016, Vol.16(1), pp.182
    Description: Domestic combustion of biomass fuels, such as wood, charcoal, crop residue and dung causes Household Air Pollution (HAP). These inhaled particulates affect more than half of the world's population, causing respiratory problems such as infection and inflammatory lung disease. We examined whether the presence of black carbon in alveolar macrophages was associated with alterations in the lung microbiome in a Malawi population. Bronchoalveolar lavage samples from 44 healthy adults were sequenced using 16S rDNA amplification to assess microbial diversity, richness and relative taxa abundance. Individuals were classified as high or low particulate exposure as determined by questionnaire and the percentage of black carbon within their alveolar macrophages. Subjects in the low and high particulate groups did not differ in terms of source of fuels used for cooking or lighting. There was no difference in alpha or beta diversity by particulate group. Neisseria and Streptococcus were significantly more abundant in samples from high particulate exposed individuals, and Tropheryma was found less abundant. Petrobacter abundance was higher in people using biomass fuel for household cooking and lighting, compared with exclusive use of electricity. Healthy adults in Malawi exposed to higher levels of particulates have higher abundances of potentially pathogenic bacteria (Streptococcus, Neisseria) within their lung microbiome. Domestic biomass fuel use was associated with an uncommon environmental bacterium (Petrobacter) associated with oil-rich niches.
    Keywords: Alveolar Macrophage ; Household Air Pollution ; Petrobacter ; Respiratory Microbiome ; Air Pollution, Indoor -- Analysis ; Lung -- Microbiology ; Particulate Matter -- Analysis
    E-ISSN: 1471-2180
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  • 4
    Language: English
    In: Chemistry – A European Journal, 13 June 2016, Vol.22(25), pp.8404-8430
    Description: Enzyme mimics or artificial enzymes are a class of catalysts that have been actively pursued for decades and have heralded much interest as potentially viable alternatives to natural enzymes. Aside from having catalytic activities similar to their natural counterparts, enzyme mimics have the desired advantages of tunable structures and catalytic efficiencies, excellent tolerance to experimental conditions, lower cost, and purely synthetic routes to their preparation. Although still in the midst of development, impressive advances have already been made. Enzyme mimics have shown immense potential in the catalysis of a wide range of chemical and biological reactions, the development of chemical and biological sensing and anti‐biofouling systems, and the production of pharmaceuticals and clean fuels. This Review concerns the development of various types of enzyme mimics, namely polymeric and dendrimeric, supramolecular, nanoparticulate and proteinic enzyme mimics, with an emphasis on their synthesis, catalytic properties and technical applications. It provides an introduction to enzyme mimics and a comprehensive summary of the advances and current standings of their applications, and seeks to inspire researchers to perfect the design and synthesis of enzyme mimics and to tailor their functionality for a much wider range of applications. : This review provides a comprehensive summary of advances in enzyme mimics research, covering supramolecular, dendrimeric, polymeric, nanoparticulate and proteinic enzyme mimics. The accessibility and tunability of different scaffolds allow enzyme mimics to have a wide variety of applications, which have been categorised herein as biological reactions, biosensors, medical uses, production of fuels, green chemistry and anti‐biofouling.
    Keywords: Catalysis ; Enzymes ; Host–Guest Systems ; Macrocycles ; Supramolecular Chemistry
    ISSN: 0947-6539
    E-ISSN: 1521-3765
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  • 5
    Language: English
    In: ChemInform, August 2016, Vol.47(35), pp.no-no
    Description: Review: 301 refs.
    Keywords: Biochemistry ; Review ; Enzymes
    ISSN: 0931-7597
    E-ISSN: 1522-2667
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  • 6
  • 7
    In: Internal Medicine Journal, September 2016, Vol.46, pp.11-12
    Description: Byline: Elizabeth Huiwen Tham, Toh Jia Ying, Evelyn Xiu Ling Loo, Anne Goh, Oon Hoe Teoh, Yap Seng Chong, Seang Mei Saw, Kenneth Kwek, Peter D Gluckman, Keith M Godfrey, Hugo Van Bever, Lynette Pei-chi Shek, Chong Mary F, Bee Wah Lee ***** No abstract is available for this article. *****
    Keywords: Food Hypersensitivity;
    ISSN: 1444-0903
    E-ISSN: 1445-5994
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