Mechanisms for co-ordinate control of motility and bioflim formation by the sensor-regulator MorA in pseudomonas spp

Ph.DDOCTOR OF PHILOSOPH

Global regulator MorA affects virulence-associated protease secretion in Pseudomonas aeruginosa PAO1

10.1371/journal.pone.0123805PLoS ONE104e012380

Recruitment of Rad51 and Rad52 to Short Telomeres Triggers a Mec1-Mediated Hypersensitivity to Double-Stranded DNA Breaks in Senescent Budding Yeast

Telomere maintenance is required for chromosome stability, and telomeres are typically replicated by the action of telomerase. In both mammalian tumor and yeast cells that lack telomerase, telomeres are maintained by an alternative recombination mechanism. Here we demonstrated that the budding yeast Saccharomyces cerevisiae type I survivors derived from telomerase-deficient cells were hypersensitive to DNA damaging agents. Assays to track telomere lengths and drug sensitivity of telomerase-deficient cells from spore colonies to survivors suggested a correlation between telomere shortening and bleomycin sensitivity. Our genetic studies demonstrated that this sensitivity depends on Mec1, which signals checkpoint activation, leading to prolonged cell-cycle arrest in senescent budding yeasts. Moreover, we also observed that when cells equipped with short telomeres, recruitments of homologous recombination proteins, Rad51 and Rad52, were reduced at an HO-endonuclease-catalyzed double-strand break (DSB), while their associations were increased at chromosome ends. These results suggested that the sensitive phenotype may be attributed to the sequestration of repair proteins to compromised telomeres, thus limiting the repair capacity at bona fide DSB sites

Plasma lipoprotein subfraction concentrations are associated with lipid metabolism and age-related macular degeneration

10.1194/jlr.M073684Journal of Lipid Research5891785-179

Lens status influences the association between CFH polymorphisms and age-related macular degeneration: Findings from two population-based studies in Singapore

10.1371/journal.pone.0119570PLoS ONE103e011957

Epidemiology and risk factors for Carbapenemase-Producing Enterobacteriaceae carriage in the hospital: a population-based nested case-control study

Objective: This study aims to study the epidemiology of Carbapenemase-producing Enterobacteriaceae (CPE) in Hong Kong. / Methods: This is a longitudinal population-based study reporting monthly CPE incidence rate and a nested case-control study for identifying risk factors for CPE carriage. The cases were patients with at least one CPE positive genotypic test, while the controls were randomly selected from the cohort with negative tests. Up to four controls per case were matched by sex, age group, and admission year-month. The independent risk factors were identified from a conditional logistic regression with potential covariates. / Results: From 1st January 2008 to 31st December 2019, 8,588 patients received CPE genotyping tests, and 2,353 had at least one positive result. Class B carbapenemase was the predominant enzyme in the samples (78.6%). The incidence rate increased from 0.04 in 2015 to 1.62 in 2019 per 10,000 person-year. In the nested case-control study, 1709 cases and 6664 controls were matched. Previous use of any beta-lactam antibiotics [Odds ratio:1.37 (1.22-1.53), p<.001] was found as an independent risk factor for carriage of CPE. / Conclusion: The carriage of CPE was found with an increasing trend in Hong Kong. Previous use of any beta-lactam antibiotics is a risk factor for CPE. / Summary: The incidence rate of Carbapenemase-producing Enterobacteriaceae is increasing in Hong Kong, with the predominant enzyme of class B carbapenemase. With multivariable conditional logistic regression, the previous use of any beta-lactam antibiotics was found as an independent risk factor for CPE carriage

Serum cholesterol efflux capacity in age-related macular degeneration and polypoidal choroidal vasculopathy

PURPOSE: To investigate serum cholesterol efflux capacity (the ability of the serum to accept cholesterol) and factors that regulate it using nuclear magnetic resonance-quantified measures of lipoprotein particle composition and size and apolipoproteins metrics in patients with age-related macular degeneration (AMD). DESIGN: Case-control study. PARTICIPANTS: Four hundred two serum samples from 80 patients with early AMD (eAMD), and 212 patients with neovascular AMD (nAMD), including 80 with typical nAMD (tAMD) and 132 with polypoidal choroidal vasculopathy (PCV), and 110 age- and gender matched control participants. METHODS: Serum from participants showed cholesterol efflux capacity measured using in vitro cell assays and lipoprotein subfractions measured using nuclear magnetic resonance (Nightingale, Ltd). Associations between cholesterol efflux capacity (measured in percentage) and lipid subfractions were investigated in the patients and control participants. MAIN OUTCOME MEASURES: Cholesterol efflux capacity and lipid subfractions in control, eAMD, and nAMD. Associations between HDL subfractions and cholesterol efflux capacity. RESULTS: Cholesterol efflux capacity was higher in patients with eAMD (68.0 ± 11.3% [mean ± standard deviation]) and nAMD (75.9 ± 27.7%) than in the control participants (56.9 ± 16.7%) after adjusting for age, gender, and use of lipid-lowering drug ( CONCLUSIONS: Serum cholesterol efflux capacity was increased in eAMD and PCV, but not tAMD, possibly reflecting differential underlying pathophysiologic features of lipid dysregulation in tAMD and PCV. Further studies should be directed toward investigating the diverse biological activities of HDL in AMD, including macular pigment transport, regulation of inflammation, and local cholesterol transport system

Genome of a thermophilic bacterium Geobacillus sp. TFV3 from Deception Island, Antarctica

Thermophilic microorganisms have always been an important part of the ecosystem, particularly in a hot environment, as they play a key role in nutrient recycling at high temperatures where most microorganisms cannot cope. While most of the thermophiles are archaea, thermophiles can also be found among some species of bacteria. These bacteria are very useful in the fundamental study of heat adaptation, and they are also important as potential sources of thermostable enzymes and metabolites. Recently, we have isolated a Gram-positive thermophilic bacterium, Geobacillus sp. TFV3 from a volcanic soil sample from Deception Island, Antarctica. This project was undertaken to analyze the genes of this thermophilic Antarctic bacterium and to determine the presence of thermal-stress adaptation proteins in its genome. The genome of Geobacillus sp. TFV3 was first purified, sequenced, assembled, and annotated. The complete genome was found to harbor genes encoding for useful thermal-stress adaptation proteins. The majority of these proteins were categorized under the family of molecular chaperone and heat shock protein. This genomic information could eventually provide insights on how the bacterium adapts itself towards high growth temperatures