Genetic Analysis of CGMP-dependent Chemosensory Signal Transduction Pathways in the Detection of Bacterial Metabolites by C. Elegans

Genetic Analysis of CGMP-dependent Chemosensory Signal Transduction Pathways in the Detection of Bacterial Metabolites by C. Elegans
Author: Jaeseok Park (Ph.D.)
Publisher:
Total Pages: 96
Release: 2019
Genre:
ISBN:

The ability of metazoans to sense and interpret the external chemical environment is conferred by the chemosensory nervous system governing the senses of smell and taste. Chemosensory neurons convey external stimuli in the form of electrical impulses, as well as by changes in gene expression. This thesis describes the genetic elucidation of a Caenorhabditis elegans molecular pathway that transduces the presence of pathogens to activate the transcription of a neuroendocrine ligand. Previously, our group has showed that secondary metabolites produced by the pathogen P. aeruginosa cause an expression pattern change of the gene coding for the C. elegans TGF-beta ligand DAF-7. Using forward and reverse genetic approaches, we identified several cGMP-related components that are essential for the pathway, including a subunit for cyclic nucleotide-gated channels, CNG-2, and a cGMP-dependent kinase, EGL-4. We show that while CNG-2 induces daf-7 expression in a calcium-dependent manner, EGL-4 likely works in a calcium-independent manner to regulate daf-7 expression. Our data suggest that EGL-4 acts by selectively promoting the transcription of neuronal genes in response to appropriate stimuli. In a separate set of experiments, we also showed that the expression of daf-7 is discretely regulated by different classes of intraflagellar transport proteins that function in cilia.

Regulatory Mechanisms of Chemosensory Signaling in Caenorhabditis Elegans

Regulatory Mechanisms of Chemosensory Signaling in Caenorhabditis Elegans
Author: Michelle Christine Krzyzanowski
Publisher:
Total Pages: 213
Release: 2015
Genre:
ISBN:

All animals rely on their ability to sense and respond to their environment to survive. While similar signal transduction pathways are implicated in both C. elegans and vertebrate chemosensation, there are still large gaps in our understanding of the mechanisms used to regulate signaling in these systems. In my thesis, I have identified a new role for the C. elegans cGMP-dependent protein kinase (PKG) EGL-4 in the negative regulation of nociceptive chemosensory signaling. Nociceptive sensory systems detect harmful stimuli and allow for the initiation of protective behavioral responses. The polymodal ASH sensory neurons are the primary nociceptors in C. elegans. The data suggest that EGL-4 negatively regulates signaling and behavior by activating known inhibitors of G protein-coupled signal transduction, RGS proteins. Using C. elegans behavioral response to aversive stimuli as the readout for neuronal activity, I provide the first evidence for PKG regulation of RGS function in sensory neurons in any system. Additionally, the suitability of a behavioral response is context-dependent, and must reflect both an animal's life history and its present internal state. Based on the integration of these variables, an animal's needs can be prioritized to optimize survival strategies. I show that cGMP movement through a gap junction neural network allows dynamic repurposing of several C. elegans head sensory neurons to regulate ASH sensitivity through EGL-4 function in response to an animal's feeding status. Such decentralized regulation of ASH signaling allows for rapid correlation between an animal's internal state and its behavioral output, and lends an unexpected modulatory flexibility to this hard-wired nociceptive neural circuit.

The Neurobiology of Olfaction

The Neurobiology of Olfaction
Author: Anna Menini
Publisher: CRC Press
Total Pages: 438
Release: 2009-11-24
Genre: Science
ISBN: 1420071998

Comprehensive Overview of Advances in OlfactionThe common belief is that human smell perception is much reduced compared with other mammals, so that whatever abilities are uncovered and investigated in animal research would have little significance for humans. However, new evidence from a variety of sources indicates this traditional view is likely

Transduction Channels in Sensory Cells

Transduction Channels in Sensory Cells
Author: Stephan Frings
Publisher: John Wiley & Sons
Total Pages: 321
Release: 2006-03-06
Genre: Science
ISBN: 3527604979

This is the first book to provide a molecular level explanation of how the senses work, linking molecular biology with sensory physiology to deduce the molecular mechanism of a key step in sensory signal generation. The editors have assembled expert authors from all fields of sensory physiology for an authoritative overview of the mechanisms of sensory signal transduction in both animals and plants. They systematically cover phototransduction, chemosensory transduction, mechanotransduction, temperature and pain perception, as well as specialized receptors for electrical and magnetic signals. Required reading for biologists, physiologists and medical researchers with an interest in sensory physiology.

E. coli in Motion

E. coli in Motion
Author: Howard C. Berg
Publisher: Springer Science & Business Media
Total Pages: 136
Release: 2008-01-11
Genre: Science
ISBN: 0387216383

Escherichia coli, commonly referred to as E. coli, has been the organism of choice for molecular genetics for decades. Its machinery and mobile behavior is one of the most fascinating topics for cell scientists. Scientists and engineers, not trained in microbiology, and who would like to learn more about living machines, can see it as a unique example. This cross-disciplinary monograph covers more than thirty years of research and is accessible to graduate students and scientists alike.

The Molecular Basis of Smell and Taste Transduction

The Molecular Basis of Smell and Taste Transduction
Author: Derek J. Chadwick
Publisher: John Wiley & Sons
Total Pages: 298
Release: 2008-04-30
Genre: Science
ISBN: 0470514523

Recent application of the techniques of molecular biology and patch-clamp physiology has led to rapid advances in understanding the molecular events in chemosensory transduction. In this book, the latest results are presented and discussed by leading scientists. The extensive coverage encompasses many important topics, including mucous domains; microchemical heterogeneity in the mucociliary complex of the olfactory epithelium; membrane currents and mechanisms of olfactory transduction, and genetic and pathological taste variation.