During inflammation neutrophils receive multiple signals that are integrated, allowing a single modified response. One mechanism for this discrimination is receptor desensitization, a process whereby ligand-receptor binding is disassociated from cell activation. We examined the effect of heterologous receptor desensitization on neutrophil chemotaxis, calcium mobilization, and arachidonic acid production, using interleukin-8 (IL-8), C5a, and N-formyl-methionyl-leucyl-phenylalanine (fMLP). We observed reciprocal inhibition with respect to chemotaxis. We demonstrated that homologous desensitization, with respect to the mobilization of intracellular calcium stores, lasted approximately 15 min. Heterologous desensitization between the fMLP receptor and the C5a receptor was reciprocal; either stimulant would diminish the cells' response to stimulation by the other for approximately 3-5 min. However, we observed a unidirectional heterologous desensitization of the IL-8 receptor by both the fMLP and the C5a receptor. This unidirectional heterologous desensitization was observed with respect to both calcium mobilization and arachidonic acid production (i.e., prestimulation of the IL-8 receptor had no effect on subsequent stimulation by either fMLP or C5a).
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Environ Microbiol
January 2024
Department of Microbiology, Oregon State University, Corvallis, Oregon, USA.
Under iron-limiting conditions, fluorescent pseudomonads acquire iron from the environment by secreting strain-specific, iron-chelating siderophores termed pyoverdines (PVD). The rhizosphere bacterium Pseudomonas protegens Pf-5 produces its own PVD but also can cross-feed on PVDs produced by other species. Previous work has found that Pf-5 continues to produce its own PVD when allowed to cross-feed, raising questions about the benefit of heterologous PVD utilisation.
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Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States.
Methods to augment Na current in cardiomyocytes hold potential for the treatment of various cardiac arrhythmias involving conduction slowing. Because the gene coding cardiac Na channel (Na1.5) is too large to fit in a single adeno-associated virus (AAV) vector, new gene therapies are being developed to enhance endogenous Na1.
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August 2023
Departamento de Biología, Facultad de Química, Ciudad Universitaria, Universidad Nacional Autónoma de México (U.N.A.M.), Ciudad de México, México.
The subunit is a potent inhibitor of the FF-ATPase of (PdFF-ATPase) and related -proteobacteria different from the other two canonical inhibitors of bacterial () and mitochondrial (IF) FF-ATPases. mimics mitochondrial IF in its inhibitory N-terminus, blocking the PdFF-ATPase activity as a unidirectional pawl-ratchet and allowing the PdFF-ATP synthase turnover. is essential for the respiratory growth of , as we showed by a knockout.
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February 2023
Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA.
Escherichia coli is the most studied and well understood microorganism, but research in this system can still be limited by available genetic tools, including the ability to rapidly integrate multiple DNA constructs efficiently into the chromosome. Site-specific, large serine-recombinases can be useful tools, catalyzing a single, unidirectional recombination event between 2 specific DNA sequences, and without requiring host proteins for functionality. Using these recombinases, we have developed a system to integrate up to 12 genetic constructs sequentially and stably into in the E.
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