scholarly journals Evolution and Design Governing Signal Precision and Amplification in a Bacterial Chemosensory Pathway

PLoS Genetics ◽  
2015 ◽  
Vol 11 (8) ◽  
pp. e1005460 ◽  
Author(s):  
Mathilde Guzzo ◽  
Rym Agrebi ◽  
Leon Espinosa ◽  
Grégory Baronian ◽  
Virginie Molle ◽  
...  
Keyword(s):  
Chemosensory Pathway

scholarly journals Two Agrobacterium tumefaciens CheW Proteins Are Incorporated into One Chemosensory Pathway with Different Efficiencies

2018 ◽  
Vol 31 (4) ◽  
pp. 460-470 ◽  
Author(s):  
Zhiwei Huang ◽  
Qingxuan Zhou ◽  
Pan Sun ◽  
Jing Yang ◽  
Minliang Guo
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Histidine Kinase ◽  
Promoter Activity ◽  
Crown Gall Tumor ◽  
Signaling Complex ◽  
Chemosensory Pathway ◽  
Dicotyledonous Plants ◽  
The Difference ◽  
Coupling Protein ◽  
And Function

Agrobacterium tumefaciens is the agent that causes crown gall tumor disease on more than 140 species of dicotyledonous plants. Chemotaxis of A. tumefaciens toward the wound sites of the host plant is the first step to recognize the host. CheW is a coupling protein that bridges the histidine kinase CheA and the chemoreceptors to form the chemotaxis core signaling complex and plays a crucial role in the assembly and function of the large chemosensory array. Unlike all previously reported chemotaxis systems, A. tumefaciens has only one major che operon but two cheW homologs (atu2075 as cheW1 and atu2617 as cheW2) on unlinked loci. The in-frame deletion of either cheW gene significantly affects A. tumefaciens chemotaxis but does not abolish the chemotaxis, unless both cheW genes were deleted. The effect of cheW2 deletion on the chemotaxis is more severe than that of cheW1 deletion. Either CheW can interact with CheA and couple it to the cell poles. The promoter activity of cheW2 is always higher than that of cheW1 under all of the tested conditions. When two cheW genes were adjusted to the same expression level by using the identical promoter, the difference between the effects of two CheW proteins on the chemotaxis still existed. Therefore, we envision that both the different molecular ratio of two CheW proteins in cell and the different affinities of two CheW proteins with CheA and chemoreceptors result in the efficiency difference of two CheW proteins in functioning in the large chemosensory array.

Vagal immune-to-brain communication: a visceral chemosensory pathway

2000 ◽  
Vol 85 (1-3) ◽  
pp. 49-59 ◽  
Author(s):  
Lisa E. Goehler ◽  
Ron P.A. Gaykema ◽  
Michael K. Hansen ◽  
Karl Anderson ◽  
Steven F. Maier ◽  
...  
Keyword(s):  
Chemosensory Pathway

scholarly journals The Role of Carotid Sinus Nerve Input in the Hypoxic-Hypercapnic Ventilatory Response in Juvenile Rats

2020 ◽  
Vol 11 ◽  
Author(s):  
Paulina M. Getsy ◽  
Gregory A. Coffee ◽  
Stephen J. Lewis
Keyword(s):  
Carotid Sinus ◽  
Nucleus Tractus Solitarius ◽  
Minute Ventilation ◽  
Respiratory Pattern ◽  
Whole Body ◽  
Carotid Sinus Nerve ◽  
Sprague Dawley ◽  
Juvenile Rats ◽  
Ventilatory Responses ◽  
Chemosensory Pathway

In juvenile rats, the carotid body (CB) is the primary sensor of oxygen (O2) and a secondary sensor of carbon dioxide (CO2) in the blood. The CB communicates to the respiratory pattern generator via the carotid sinus nerve, which terminates within the commissural nucleus tractus solitarius (cNTS). While this is not the only peripheral chemosensory pathway in juvenile rodents, we hypothesize that it has a unique role in determining the interaction between O2 and CO2, and consequently, the response to hypoxic-hypercapnic gas challenges. The objectives of this study were to determine (1) the ventilatory responses to a poikilocapnic hypoxic (HX) gas challenge, a hypercapnic (HC) gas challenge or a hypoxic-hypercapnic (HH) gas challenge in juvenile rats; and (2) the roles of CSN chemoafferents in the interactions between HX and HC signaling in these rats. Studies were performed on conscious, freely moving juvenile (P25) male Sprague Dawley rats that underwent sham-surgery (SHAM) or bilateral transection of the carotid sinus nerves (CSNX) 4 days previously. Rats were placed in whole-body plethysmographs to record ventilatory parameters (frequency of breathing, tidal volume and minute ventilation). After acclimatization, they were exposed to HX (10% O2, 90% N2), HC (5% CO2, 21% O2, 74% N2) or HH (5% CO2, 10% O2, 85% N2) gas challenges for 5 min, followed by 15 min of room-air. The major findings were: (1) the HX, HC and HH challenges elicited robust ventilatory responses in SHAM rats; (2) ventilatory responses elicited by HX alone and HC alone were generally additive in SHAM rats; (3) the ventilatory responses to HX, HC and HH were markedly attenuated in CSNX rats compared to SHAM rats; and (4) ventilatory responses elicited by HX alone and HC alone were not additive in CSNX rats. Although the rats responded to HX after CSNX, CB chemoafferent input was necessary for the response to HH challenge. Thus, secondary peripheral chemoreceptors do not compensate for the loss of chemoreceptor input from the CB in juvenile rats.

scholarly journals Emergent myxobacterial behaviors arise from reversal suppression induced by kin contacts

2021 ◽  
Author(s):  
Rajesh Balagam ◽  
Pengbo Cao ◽  
Govind P Sah ◽  
Zhaoyang A Zhang ◽  
Daniel Wall ◽  
...  
Keyword(s):  
Kin Recognition ◽  
Social Recognition ◽  
Collective Behaviors ◽  
Large Numbers ◽  
Wide Range ◽  
Chemosensory Pathway ◽  
Cellular Slime ◽  
Physical Interactions ◽  
Mechanistic Basis ◽  
Emergent Behaviors

A wide range of biological systems - from microbial swarms to bird flocks, display emergent behaviors driven by coordinated movement of individuals. To this end, individual organisms interact by recognizing their kin and adjusting their motility based on others around them. However, even in the best-studied systems, the mechanistic basis of the interplay between kin recognition and motility coordination is not understood. Here, using a combination of experiments and mathematical modeling, we uncover the mechanism of an emergent social behavior in Myxococcus xanthus. By overexpressing the cell surface kin recognition receptors, TraA and TraB, large numbers of cells adhere to one another and form organized macroscopic circular aggregates that spin clockwise or counterclockwise. Mechanistically, TraAB adhesion results in sustained cell-cell contacts that signal the Frz chemosensory pathway. In turn, cell reversals are suppressed and circular aggregates form as the result of cells' ability to follow cellular slime trails. Furthermore, our in-silico simulations demonstrate a remarkable ability to predict self-organization patterns when phenotypically distinct strains are mixed. Therefore, this work provides key mechanistic insights into M. xanthus social interactions and demonstrates how social recognition transforms physical interactions into emergent collective behaviors.

scholarly journals Roles of Chemosensory Pathways in Transient Changes in Swimming Speed of Rhodobacter sphaeroides Induced by Changes in Photosynthetic Electron Transport

1999 ◽  
Vol 181 (1) ◽  
pp. 34-39 ◽  
Author(s):  
Simona Romagnoli ◽  
Judith P. Armitage
Keyword(s):  
Electron Transport ◽  
Light Intensity ◽  
Rhodobacter Sphaeroides ◽  
Swimming Speed ◽  
Photosynthetic Electron Transport ◽  
Free Swimming ◽  
Chemosensory Pathway ◽  
Transposon Mutants ◽  
Transport Inhibitors ◽  
Chemosensory Pathways

ABSTRACT The response of free-swimming Rhodobacter sphaeroidesto increases and decreases in the intensity of light of different wavelengths was analyzed. There was a transient (1 to 2 s) increase in swimming speed in response to an increase in light intensity, and there was a similar transient stop when the light intensity decreased. Measurement of changes in membrane potential and the use of electron transport inhibitors showed that the transient increase in swimming speed, following an increase in light intensity, and the stop following its decrease were the result of changes in photosynthetic electron transport. R. sphaeroides has two operons coding for multiple homologs of the enteric chemosensory genes. Mutants in the first chemosensory operon showed wild-type photoresponses. Mutants with the cheA gene of the second operon (cheA II) deleted, either with or without the first operon present, showed inverted photoresponses, with free-swimming cells stopping on an increase in light intensity and increasing swimming speed on a decrease. These mutants also lacked adaptation. Transposon mutants with mutations incheA II, which also reduced expression of downstream genes, however, showed no photoresponses. These results show that (i) free-swimming cells respond to both an increase and a decrease in light intensity (tethered cells only show the stopping on a step down in light intensity), (ii) the signal comes from photosynthetic electron transfer, and (iii) the signal is primarily channelled through the second chemosensory pathway. The different responses shown by thecheA II deletion and insertion mutants suggest that CheWII is required for photoresponses, and a third sensory pathway can substitute for CheAII as long as CheWII is present. The inverted response suggests that transducers are involved in photoresponses as well as chemotactic responses.

scholarly journals Interaction of chemosensory, visual, and statocyst pathways in Hermissenda crassicornis.

1978 ◽  
Vol 71 (2) ◽  
pp. 177-194 ◽  
Author(s):  
D L Alkon ◽  
T Akaike ◽  
J Harrigan
Keyword(s):  
Hair Cells ◽  
Ganglion Cells ◽  
Preliminary Investigation ◽  
Neural Mechanisms ◽  
Synaptic Inhibition ◽  
Behavioral Choice ◽  
Intersensory Interaction ◽  
Chemosensory Pathway ◽  
Optic Ganglion ◽  
Stimulation Of

Neurons in the cerebropleural ganglia (CPG), photoreceptors in the eye, optic ganglion cells, and statocyst hair cells of the nudibranch mollusk Hermissenda crassicornis responded in specific ways, as recorded intracellularly, to stimulation of the chemosensory pathway originating at the tentacular chemoreceptors as well as to stimulation of the visual pathway originating at the photoreceptors. Synaptic inhibition of photoreceptors occurs via the chemosensory pathway. The possible significance of such intersensory interaction is discussed with reference to preliminary investigation of the animal's gustatory behavior and possible neural mechanisms of behavioral choice.

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