The Use of Ultrasounds in the Preparation of Chemosensory Microstructures

In many fields, the goal is to obtain structures with small dimensions in the order of micro/nanometers. Small-sized systems can have countless applications in various industries such as cosmetology, medicine, and nutrition technology. Many techniques are used to obtain the most miniature possible spheres, such as interference with the composition, use of surfactants, or mechanical interference: rapid mixing, increased pressure, and ultrasound. The use of ultrasound in the development of colloidal systems can be an effective method of reducing the size of particles of dispersed phase and influencing the functions they represent. An important aspect here is the time during which the ultrasound is used. In this work, the influence of ultrasound on the chemosensory properties and size of produced ion-sensitive microspheres was investigated and compared. The chemosensory response of the developed microspheres was studied using spectrophotometry and spectrofluorimetry, while the size of the microsphere optodes was estimated by confocal microscopy.

Impact of Exercise Timing on Chemosensory Response, Appetite, and Energy Intake in Lean Males

Background: High-intensity exercise can have an anorectic impact, leading to negative energy balance. Several studies have reported that the practice of physical activity could also cause a shift in perceptions and preferences, causing a change in food intakes. Objective: This study aimed to question to what extent the timing of exercise in relation to a meal could have an impact on olfaction and gustation, appetite, and food choices. Methods: Twelve males aged 25 (4) years with a body mass index of 22.4 (2.0) kg/m2 attended two experimental visits in a counterbalanced fashion. The participants consumed a standardized breakfast between 7:00 and 7:30 a.m. and were subjected to smell and taste tests upon arrival at the laboratory (8:30 a.m.). In the EX9:40 visit, the participants performed a 30-min exercise session (70% of maximum oxygen uptake) at 9:40 a.m., followed by a 90-min sedentary break. In EX10:30, the participants first took part in the 90-min sedentary break and then performed the 30-min exercise session at 10:30 a.m. Taste and smell tests were performed again at 11:40 a.m., immediately followed by an ad libitum buffet-style meal. Visual analog scales were used to report appetite sensations during the session and satiety quotients around the lunch. Results: There was no difference in energy intakes between the EX9:40 (596 [302] kcal) and EX10:30 (682 [263] kcal) conditions (p = .459). There was no condition effect for the taste and smell sensations (all ps > .05), appetite sensation, or satiety quotients around the meal (all ps > .05). Conclusion: Exercise timing in the morning had no effect on taste and smell perceptions, appetite sensations, or energy intakes.

Exploration of fluorescence behavior of an imidazolium-based chemosensor in solution and in the solid state and its turn-on response to Al3+ in pure aqueous medium

An imidazolium-based quinoline framework is constructed, and its fluorescence behaviour studies with fluorescence turn-on chemosensory response to the selective detection of Al3+ in aqueous medium are discussed in detail.

Response kinetics in the complex chemotaxis signalling pathway of Rhodobacter sphaeroides

Chemotaxis is one of the best-characterized signalling systems in biology. It is the mechanism by which bacteria move towards optimal environments and is implicated in biofilm formation, pathogenesis and symbiosis. The properties of the bacterial chemosensory response have been described in detail for the single chemosensory pathway of Escherichia coli . We have characterized the properties of the chemosensory response of Rhodobacter sphaeroides , an α-proteobacterium with multiple chemotaxis pathways, under two growth conditions allowing the effects of protein expression levels and cell architecture to be investigated. Using tethered cell assays, we measured the responses of the system to step changes in concentration of the attractant propionate and show that, independently of the growth conditions, R. sphaeroides is chemotactic over at least five orders of magnitude and has a sensing profile following Weber's Law. Mathematical modelling also shows that, as E. coli , R. sphaeroides is capable of showing fold-change detection (FCD). Our results indicate that general features of bacterial chemotaxis such as the range and sensitivity of detection, adaptation times, adherence to Weber's Law and the presence of FCD may be integral features of chemotaxis systems in general, regardless of network complexity, protein expression levels and cellular architecture across different species.

Participation of CheR and CheB in the chemosensory response of Campylobacter jejuni

Campylobacter jejuni is a leading cause of bacterial gastroenteritis in humans and a commensal bacterium of the intestinal tracts of animals, especially poultry. Chemotaxis is an important determinant for chicken colonization of C. jejuni. Adaptation has a crucial role in the gradient-sensing mechanism that underlies chemotaxis. The genome sequence of C. jejuni reveals the presence of genes encoding putative adaptation proteins, CheB and CheR. In-frame deletions of cheB, cheR and cheBR were constructed and the chemosensory behaviour of the resultant mutants was examined on swarm plates. CheB and CheR proteins significantly influence chemotaxis but are not essential for this behaviour to occur. Increased mobility of two methyl-accepting chemotaxis proteins (MCPs), DocC and Tlp1, during SDS-PAGE was detected in the mutants lacking functional CheB in the presence of CheR, presumably resulting from stable methylation of receptors. In vitro studies using tissue culture revealed that deletion of cheR resulted in hyperadherent and hyperinvasive phenotypes, while deletion of cheB resulted in nonadherent, noninvasive phenotypes. Furthermore, the ΔcheBR mutant showed significantly reduced ability to colonize chick caeca. Our data suggest that modification of chemoreceptors by the CheBR system is involved in regulation of chemotaxis in C. jejuni although CheB is apparently not controlled by phosphorylation.

New Motion Analysis System for Characterization of the Chemosensory Response Kinetics of Rhodobacter sphaeroides under Different Growth Conditions

ABSTRACTWe developed a new set of software tools that enable the speed and response kinetics of large numbers of tethered bacterial cells to be rapidly measured and analyzed. The software provides precision, accuracy, and a good signal-to-noise ratio combined with ease of data handling and processing. The software was tested on the single-cell chemosensory response kinetics of large numbers ofRhodobacter sphaeroidescells grown under either aerobic or photoheterotrophic conditions and either in chemostats or in batch cultures, allowing the effects of growth conditions on responses to be accurately measured. Aerobically and photoheterotrophically grownR. sphaeroidesexhibited significantly different chemosensory response kinetics and cell-to-cell variability in their responses to 100 μM propionate. A greater proportion of the population of aerobically grown cells responded to a 100 μM step decrease in propionate; they adapted faster and showed less cell-to-cell variability than photosynthetic populations. Growth in chemostats did not significantly reduce the measured cell to cell variability but did change the adaptation kinetics for photoheterotrophically grown cells.

Tandem evolution of diet and chemosensory responses in snakes

Adaptations to foraging requirements have molded sensory capacities of animals in intriguing and sometimes spectacular ways, including evolution of echolocation by bats and infrared detection by pitvipers, as well as of location of prey using lingually sampled chemical cues by actively foraging lizards. Among snakes, specialized diets and geographic differences in diets have evolved many times. Because snakes identify prey by vomerolfactory analysis of chemicals sampled by tongue-flicking, it may be predicted that responsiveness to lingually sampled chemical cues corresponds to diet: It should be much stronger to prey included in than excluded from specialized diets and should covary with geographic dietary differences in prey generalists. Breeding studies in Thamnophis elegans showed that greater responsiveness to local prey in populations having geographically variable diets has a heritable component. Whether strong chemosensory response evolves to match current diet has not been established for snakes using the comparative method. For all paired comparisons of dietary change now available, chemosensory behavior changed so that strongest responses were limited to cues from the current prey. Because diets were specialized and snakes were ingestively naive hatchlings in almost all comparisons, the basis for observed relationships is innate rather than experiential. Snake chemosensory responses have evolved to match current diets.