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Author (up) Ma, L.; Wang, S.; Wang, D.; Parsek, M.R.; Wozniak, D.J. file  url
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  Title The roles of biofilm matrix polysaccharide Psl in mucoid Pseudomonas aeruginosa biofilms Type Journal Article
  Year 2012 Publication FEMS Immunology and Medical Microbiology Abbreviated Journal FEMS Immunol Med Microbiol  
  Volume 65 Issue 2 Pages 377-380  
  Keywords Biofilms--growth & development; Gene Deletion; Genes, Bacterial; Polysaccharides, Bacterial--metabolism; Pseudomonas aeruginosa--growth & development, metabolism, physiology  
  Abstract The opportunistic pathogen Pseudomonas aeruginosa causes life-threatening, persistent infections in patients with cystic fibrosis (CF). Persistence is attributed to the ability of these bacteria to form structured communities (biofilms). Biofilms rely on an extracellular polymeric substances matrix to maintain structure. Psl exopolysaccharide is a key matrix component of nonmucoid biofilms, yet the role of Psl in mucoid biofilms is unknown. In this report, using a variety of mutants in a mucoid P. aeruginosa background, we found that deletion of Psl-encoding genes dramatically decreased their biofilm formation ability, indicating that Psl is also a critical matrix component of mucoid biofilms. Our data also suggest that the overproduction of alginate leads to mucoid biofilms, which occupy more space, whereas Psl-dependent biofilms are densely packed. These data suggest that Psl polysaccharide may have significant contributions in biofilm persistence in patients with CF and may be helpful for designing therapies for P. aeruginosa CF infection.  
  Call Number Serial 432  
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Author (up) Maciag-Dorszynska, M.; Ignatowska, M.; Janniere, L.; Wegrzyn, G.; Szalewska-Palasz, A. file  url
openurl 
  Title Mutations in central carbon metabolism genes suppress defects in nucleoid position and cell division of replication mutants in Escherichia coli Type Journal Article
  Year 2012 Publication Gene Abbreviated Journal Gene  
  Volume 503 Issue 1 Pages 31-35  
  Keywords Bacterial Structures--ultrastructure; Carbon--metabolism; Cell Division--genetics; DNA Replication--genetics; Escherichia coli--genetics, metabolism, ultrastructure; Escherichia coli Proteins--genetics, metabolism; Gene Deletion; Mutation  
  Abstract A genetic link of the carbon metabolism and DNA replication was recently reported for the representative of Gram-negative bacteria, Escherichia coli. Our studies showed that the viability of thermosensitive replication mutants at high temperature can be improved or fully recovered by deleting certain genes of central carbon metabolism (CCM). In order to improve our understanding of this phenomenon, in this study we analyzed the length and nucleoid distribution of suppressed thermosensitive replication mutants. The dysfunctions in the replication machinery generally lead to formation of elongated cells (termed filaments) that originate from an inhibition of cell division dependent on replication-stress, and to abnormal distribution and compaction of nucleoids. The results reported here provide evidence that deletion of the pta and ackA CCM genes significantly reduces observed cell length in the replication mutants dnaA46, dnaB8, dnaE486, dnaG(ts) and dnaN159. A weaker effect was shown in the tktB dnaE486 double mutant. The CCM enzyme dysfunction restored also the nucleoid shape and position in double mutants. The specificity of these effects was confirmed by overexpression of fully functional genes coding for relevant CCM enzymes, which caused the reversion to the initial filamentous and nucleoid phenotypes. These results indicate that CCM mutations can rescue (or reduce) the cell division defects resulting from various replication mutations. We thus suggest that the replication-metabolism connection may serve as a general mechanism affecting DNA duplication at various levels to adjust this process and the cell division to the status of cell physiology.  
  Call Number Serial 444  
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Author (up) Parsons, A.B.; Brost, R.L.; Ding, H.; Li, Z.; Zhang, C.; Sheikh, B.; Brown, G.W.; Kane, P.M.; Hughes, T.R.; Boone, C. file  url
doi  openurl
  Title Integration of chemical-genetic and genetic interaction data links bioactive compounds to cellular target pathways Type Journal Article
  Year 2004 Publication Nature Biotechnology Abbreviated Journal Nat Biotechnol  
  Volume 22 Issue 1 Pages 62-69  
  Keywords Biotechnology/*methods; Cluster Analysis; Drug Industry/*methods; *Drug Resistance; Fungal Proteins/metabolism; Gene Deletion; *Gene Expression Regulation; Mutation; Pharmacogenetics; Proton-Translocating ATPases/metabolism; Saccharomyces cerevisiae/*genetics; Software  
  Abstract Bioactive compounds can be valuable research tools and drug leads, but it is often difficult to identify their mechanism of action or cellular target. Here we investigate the potential for integration of chemical-genetic and genetic interaction data to reveal information about the pathways and targets of inhibitory compounds. Taking advantage of the existing complete set of yeast haploid deletion mutants, we generated drug-hypersensitivity (chemical-genetic) profiles for 12 compounds. In addition to a set of compound-specific interactions, the chemical-genetic profiles identified a large group of genes required for multidrug resistance. In particular, yeast mutants lacking a functional vacuolar H(+)-ATPase show multidrug sensitivity, a phenomenon that may be conserved in mammalian cells. By filtering chemical-genetic profiles for the multidrug-resistant genes and then clustering the compound-specific profiles with a compendium of large-scale genetic interaction profiles, we were able to identify target pathways or proteins. This method thus provides a powerful means for inferring mechanism of action.  
  Call Number Serial 339  
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Author (up) Schmucker, C.; Seeliger, M.; Humphries, P.; Biel, M.; Schaeffel, F. file  url
openurl 
  Title Grating acuity at different luminances in wild-type mice and in mice lacking rod or cone function Type Journal Article
  Year 2005 Publication Investigative Ophthalmology & Visual Science Abbreviated Journal Invest Ophthalmol Vis Sci  
  Volume 46 Issue 1 Pages 398-407  
  Keywords Animals; Cyclic Nucleotide-Gated Cation Channels; Female; Gene Deletion; Ion Channels/genetics; *Lighting; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Motor Activity/physiology; Photoreceptor Cells, Vertebrate/*physiology; Rhodopsin/genetics; Rod Opsins/genetics; Space Perception/*physiology; Visual Acuity/*physiology  
  Abstract PURPOSE: The mouse eye has become an important model in vision research. However, it is not known how visual acuity changes with luminance. Therefore, grating acuity of mice was measured at different luminances in an automated optomotor paradigm. Furthermore, mutant mice lacking either rods (RHO-/- and CNGB1-/-) or cones (CNGA3-/-), or both, were studied to determine the rod and cone contribution to visual acuity. METHODS: Freely ranging individual mice were automatically tracked at a 25-Hz sampling rate with a self-programmed video system in a large rotating optomotor drum. The drum had a square-wave grating inside with adjustable spatial frequency. The angular speed of the mice with respect to the center of the drum and the angular orientation of the snout-tail body axis were analyzed. In addition, the motor activity of the wild-type mice was recorded at different luminances. RESULTS: The optomotor drum provided reliable data on visual input to the mouse's behavior and was convenient to use, since the experimenter's had only to place the mice individually in a Perspex cylinder. Optomotor grating acuity of the wild-type mice was limited to 0.3 to 0.4 cyc/deg. Maximum optomotor responses were obtained at 0.1 to 0.2 cyc/deg. The importance of visual input declined monotonically with decreasing luminance (30 cd/m2, 100%; 0.1 cd/m2, 76.4%; 0.005 cd/m2, 45.9%; and darkness, -9%). Mice lacking functional rods were able to resolve gratings up to 0.1 cyc/deg at 30 cd/m2. Surprisingly, mice lacking functional cones had an optomotor acuity that was similar to the wild-type. Double-knockout mice without rods and cones had no detectable grating acuity. CONCLUSIONS: Because the visual system of the mouse is more responsive at bright luminances, experiments in which visual input is important should be performed in photopic conditions (30 cd/m2 or even more). Apparently, spatial vision is governed by the rod system, which is not saturated in the mesopic or low photopic range. Mice lacking both rods and cones have no detectable grating acuity, indicating that the retinal melanopsin system does not contribute to spatial vision.  
  Call Number Serial 2066  
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