Browsing by Subject "Chemotaxis"

Now showing 1 - 4 of 4
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    Bacterial Chemotaxis And Biofilm Formation Genes In Primary And Secondary Endodontic Infections: A Whole-Metagenome Shotgun-Based Study.
    (2023-08) Mansour, Dina
    Purpose: To identify genes encoding the bacterial chemotaxis and biofilm formation pathway in primary and secondary root canal infections using whole genome shotgun sequencing. Materials and Methods: Thirty-seven samples from patients with primary and secondary root canal infections were evaluated using Shotgun sequencing. The distribution were assessed of bacterial species and functional genes, including genes encoding for chemotaxis and biofilm pathway. Libraries were made using 1⁄4 Nextera XT reations and sequencing was done on the Novaseq with a target of 15-20M reads per sample. Taxonomic and functional annotations were made using MetaPhIAn3 and HUMAnN3. The Mann Whitney test was used to compare differences in gene abundance between primary and secondary infections. Results: The study identified 19 chemotaxis and 77 biofilm genes. Prevalent bacteria with chemotaxis genes were Fusobacterium nucleatum (62%), Pseudopropionibacterium propionicum (21.6%), Selenomonas sputigena (10.8%), Desulfobulbus oralis (8.1%), and Campylobacter curvus (8.1%). Top chemotaxis genes included K10540: methyl-galactoside transport system substrate-binding protein (26/37) 70%, K10439 ribose transport system substrate-binding protein (21/37) 56%, K03413: two-component system, chemotaxis family, response regulator CheY (19/37) 51%, K02556: chemotaxis protein MotA (16/37) 43%, K02557 chemotaxis protein MotB (14/37) 37%. The prevalent bacteria encoding biofilm genes were Fusobacterium nucleatum (45.9%), Desulfobulbus oralis (8.1%), Campylobacter curvus (24.3%), Selenomonas sputigena (13%), and Eubacterium infirmum (43%). The top biofilm-related genes were K00688: starch phosphorylase (30/37) 81%, K00975: glucose-1-phosphate adenylyltransferase (30/37) 81%, K03092: RNA polymerase sigma-54 factor (23/37) 62%,K07173: S-ribosylhomocysteine lyase (24/37) 64%, K00640: serine O-acetyltransferase (23/37) 62%. Heatmap figures illustrated the abundance of these genes in the samples. Conclusion: Bacteria carrying chemotaxis and biofilm pathway genes included Fusobacterium nucleatum, Pseudopropionibacterium propionicum, Selenomonas sputigena, Desulfobulbus oralis, and Campylobacter curvus. The study provides valuable insights into potential targets for future research and treatment in root canal infections.
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    Chemotaxis and phonotaxis in a two-choice shuttle tank by bigheaded carps
    (2023-03-09) Culotta, Jackie; Vetter, Brooke, J; Mensinger, Allen, F; Kramer, Cassandra, A; Ervin, Marie, L; culot007@d.umn.edu; Culotta, Jackie; Laboratory of Dr. Allen Mensinger
    Dissolved carbon dioxide avoidance in silver and bighead carps. Additionally, carp were conditioned to associate broadband sound from outboard boat motors (0.06 – 10 kHz, ~150 dB re 1 μPa) with CO2 application (~35,000 ppm). Phonotaxis trials were conducted over one to four weeks in a both a small (80 L) and large (3475 L) two-choice shuttle tank.
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    Mathematical models of bacterial chemotaxis
    (2010-01) Xin, Xiangrong
    In response to environmental signals such as light, temperature or chemicals, motile organisms can change their behavior by directed movement toward or away from the signal, by changing their speed of movement and/or frequency of turning. The process is called chemotaxis. E. coli employs chemotaxis to move toward favorable locations. E. coli chemotaxis is a widely studied system. The recent research mainly concentrates on receptor clustering, which is established to account for the dramatic features of the system such as high sensitivity, precise adaptation, and robustness. There are multiple levels of organization of a receptor cluster, and researchers are gaining insights into its structure-function relationship. We hypothesize that multiple-level molecular interactions exist in the receptor cluster, and each of them contributes specific functions to the high-performance signaling. To test it, we first develop a model based on the experimental observation that the most permanent clusters of receptor homodimers are trimers of dimers. We only consider the interactions among dimers within a trimer, called intratrimer interactions. We show that the model can reproduce most of the experimentally-observed behaviors, including excitation, adaptation, high sensitivity, and robustness to parameter variations. In addition, the model makes a number of new predictions as to how the adaptation time varies with the expression level of proteins. Second, we use the approaches of multi-time-scale analysis and mean-field theory to perform model reduction, and obtain two low-dimension models. They successfully capture the output of the original model. Third, we develop a free-energy-based model for a cluster of coupled trimers, emphasizing the interactions among trimers, called intertrimer interactions. We use the model to explain high cooperativity in kinase activity responses by the cheRcheB mutants with overexpression of Tar or Tsr. Last, we develop a stochastic model of adaptation with the mobile CheR and CheB and show some preliminary results.
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    An unconventional myosin is necessary for chemotaxis in Dictyostellium discoideum.
    (2009-08) Breshears, Laura Marie
    Directed cell migration (chemotaxis) is a fundamental biological process necessary for embryonic development, wound healing, and proper function of the immune system. Chemotaxis also plays a significant role in many developmental disorders and post-embryonic diseases in humans, such as cancer. Chemotaxis is driven by extracellular cues that act, in large part, to induce changes in the actin cytoskeleton, such as actin polymerization, that facilitate directed cell migration. Myosins are actin-associated motors that have a variety of functions in different cellular contexts. Myosins can effect cortical tension, pseudopod and filopodia formation, phagocytosis, the function of sensory structures, and the basic mechanics of cell motility. Members of the MyTH/FERM family of unconventional myosins all have roles in actin-based processes and one member, vertebrate myosin X, has recently been shown to play a role in actin dynamics in response to extracellular migration cues. The social amoeba Dictyostelium discoideum is a powerful model system for dissecting chemoattractant signaling pathways and identifying the cytoskeletal components necessary for directed cell migration. MyoG is a novel unconventional myosin characterized by two MyTH/FERM domains in its tail region. The potential role of this myosin in Dictyostelium cell migration was investigated by analyzing the phenotype of three independent myoG null mutants. The initial stages of Dictyostelium development, induced by starvation, depend on chemotaxis to cAMP, resulting in the formation of a multi-cellular aggregate. Upon starvation myoG — cells fail to aggregate, arresting as a smooth monolayer of cells. The myoG — cells neither polarize in a cAMP gradient nor do they chemotax toward the cAMP source. Analysis of the ability of myoG — cells to polymerize actin in response to cAMP revealed that the response is dampened in the mutants. myoG — cells are also defective in signaling to PI3K in response to cAMP. These data show that while the mutant cells retain some ability to respond to the gradient, the major pathways regulating polarity and chemotaxis are not functional. The mutant phenotype suggests that MyoG acts in transducing the chemotactic signal from the cAMP receptor to PI3K and the actin cytoskeleton, facilitating the morphological changes that lead to polarization and directional migration. The role of MyoG in chemotactic signaling represents a novel function for an unconventional myosin. The work presented here clearly demonstrates that MyoG is necessary for signaling from the cAMP receptor to both PI3K and the actin cytoskeleton. Sequence analysis shows that there is no direct homologue of MyoG in other organisms, but the high degree of conservation of the chemotactic signaling pathways indicates that there are likely to be functional homologues in higher eukaryotic cells, such as neutrophils, that rely on chemotaxis for cellular function.