Stimulus Concentration Research Articles

Deciphering Peripheral Taste Neuron Diversity: Using Genetic Identity to Bridge Taste Bud Innervation Patterns and Functional Responses.

Peripheral taste neurons exhibit functional, genetic, and morphological diversity, yet understanding how or if these attributes combine into taste neuron types remains unclear. In this study, we used male and female mice to relate taste bud innervation patterns to the function of a subset of proenkephalin-expressing (Penk+) taste neurons. We found that taste arbors (the portion of the axon within the taste bud) stemming from Penk+ neurons displayed diverse branching patterns and lacked stereotypical endings. The range in complexity observed for individual taste arbors from Penk+ neurons mirrored the entire population, suggesting that taste arbor morphologies are not primarily regulated by neuron type. Notably, the distinguishing feature of arbors from Penk+ neurons was their propensity to come within 110 nm (in apposition with) different types of taste-transducing cells within the taste bud. This finding is contrary to the expectation of genetically defined taste neuron types that functionally represent a single stimulus. Consistently, further investigation of Penk+ neuron function revealed that they are more likely to respond to innately aversive stimuli -sour, bitter and high salt concentrations - as compared to the full taste population. Penk+ neurons are less likely to respond to non-aversive stimuli -sucrose, umami, and low salt- compared to the full population. Our data support the presence of a genetically defined neuron type in the geniculate ganglion that is responsive to innately aversive stimuli. This implies that genetic expression might categorize peripheral taste neurons into hedonic groups, rather than simply identifying neurons that respond to a single stimulus.Significance Statement Peripheral taste neuron coding has been heavily debated. Our study delves into this issue by leveraging genetic expression in a specific neuron subset to relate peripheral innervation patterns to functional taste responses. We examined a taste neuron type that appears to be in apposition with multiple taste-transducing cell types and responds to innately aversive concentrations of sour, bitter, and high NaCl stimuli. These collective observations suggest that genetic markers can delineate groups of neurons sharing similar hedonic responses rather than categorizing neurons solely based on individual taste qualities.

Looping Flexible Fluoropolymer Microcapillary Film Extends Analysis Times for Vertical Microfluidic Blood Testing.

The microfluidic measurement of capillary flow can be used to evaluate the response of biological samples to stimulation, where distance and velocity are altered. Melt-extruded multi-bored microfluidic capillaries allow for high-throughput testing with low device cost, but simple devices may limit control over sample flow when compared to the more complex "lab-on-a-chip" devices produced using advanced microfluidic fabrication methods. Previously, we measured the dynamics of global haemostasis stimulated by thrombin by dipping straight vertical microcapillaries into blood, but only the most rapid response could be monitored, as flow slowed significantly within 30 s. Here, we show an innovative method to extend both the stimulation process and flow measurement time without increasing the cost of the device by adding simple loops to the flexible extruded device. The loops enable longer time-scale measurements by increasing resistance to flow, thereby reducing the dependence on high stimulus concentrations for rapid reactions. The instantaneous velocity and equilibrium heights of straight and looped vertical microcapillary films were assessed with water, plasma and whole blood, showing that the loops create additional frictional resistances, reduce flow velocity and prolong residence times for increased time scales of the stimulation process. A modified pressure balance model was used to capture flow dynamics with the added loop. Looped devices loaded with thrombin and collagen showed an improved detection of blood stimulation responses even with lower stimulus concentrations, compared to straight vertical capillaries. Thrombin-activated blood samples in straight capillaries provided a maximum measurement zone of only 4 mm, while the looped design significantly increased this to 11 mm for much longer time scale measurements. Our results suggest that extending stimulation times can be achieved without complex microfluidic fabrication methods, potentially improving concentration-response blood stimulation assays, and may enhance the accuracy and reliability. We conclude adding a loop to low-cost extruded microfluidic devices may bring microfluidic devices closer to delivering on their promise of widespread, decentralized low-cost evaluation of blood response to stimulation in both research and clinical settings.

Gaps in our understanding of how vagal afferents to the small intestinal mucosa detect luminal stimuli.

Vagal afferents to the gastrointestinal tract are crucial for the regulation of food intake, signaling negative feedback that contributes to satiation and positive feedback that produces appetition and reward. Vagal afferents to the small intestinal mucosa contribute to this regulation by sensing luminal stimuli and reporting this information to the brain. These afferents respond to mechanical, chemical, thermal, pH, and osmolar stimuli, as well as to bacterial products and immunogens. Surprisingly, little is known about how these stimuli are transduced by vagal mucosal afferents or how their transduction is organized among these afferents' terminals. Furthermore, the effects of stimulus concentration ranges or physiological stimuli on vagal activity have not been examined for some of these stimuli. Also, detection of luminal stimuli has rarely been examined in rodents, which are most frequently used for studying small intestinal innervation. Here we review what is known about stimulus detection by vagal mucosal afferents and illustrate the complexity of this detection using nutrients as an exemplar. The accepted model proposes that nutrients bind to taste receptors on enteroendocrine cells (EECs), which excite them, causing the release of hormones that stimulate vagal mucosal afferents. However, evidence reviewed here suggests that although this model accounts for many aspects of vagal signaling about nutrients, it cannot account for all aspects. A major goal of this review is therefore to evaluate what is known about nutrient absorption and detection and, based on this evaluation, identify candidate mucosal cells and structures that could cooperate with EECs and vagal mucosal afferents in stimulus detection.

Processing stimulus dynamics by the NF-κB network in single cells.

Cells at the site of an infection experience numerous biochemical signals that vary in amplitude, space, and time. Despite the diversity of dynamic signals produced by pathogens and sentinel cells, information-processing pathways converge on a limited number of central signaling nodes to ultimately control cellular responses. In particular, the NF-κB pathway responds to dozens of signals from pathogens and self, and plays a vital role in processing proinflammatory inputs. Studies addressing the influence of stimulus dynamics on NF-κB signaling are rare due to technical limitations with live-cell measurements. However, recent advances in microfluidics, automation, and image analysis have enabled investigations that yield high temporal resolution at the single-cell level. Here, we summarize the recent research which measures and models the NF-κB response to pulsatile and fluctuating stimulus concentrations, as well as different combinations and sequences of signaling molecules. Collectively, these studies show that the NF-κB network integrates external inflammatory signals and translates these into downstream transcriptional responses.

Reduced neural responses to pleasant odor stimuli after acute psychological stress is associated with cortisol reactivity

Acute stress alters olfactory perception. However, little is known about the neural processing of olfactory stimuli after acute stress exposure and the role of cortisol in such an effect. Here, we used an event-related olfactory fMRI paradigm to investigate brain responses to odors of different valence (unpleasant, pleasant, or neutral) in healthy young adults following an acute stress (Trier Social Stress Test, TSST) induction (N = 22) or a non-stressful resting condition (N = 22). We obtained the odor pleasantness, intensity, and familiarity ratings after the acute stress induction or resting condition. We also measured the participants' perceived stress and salivary cortisol at four time points during the procedure. We found a stress-related decrease in brain activation in response to the pleasant, but not to the neutral or unpleasant odor stimuli in the right piriform cortex extending to the right amygdala, the right orbitofrontal cortex, and the right insula. In addition, activation of clusters within the regions of interest were negatively associated with individual baseline-to-peak increase in salivary cortisol levels after stress. We also found increased functional connectivity between the right piriform cortex and the right insula after stress when the pleasant odor was presented. The strength of the connectivity was positively correlated with increased perceived stress levels immediately after stress exposure. These results provide novel evidence for the effects of acute stress in attenuating the neural processing of a pleasant olfactory stimulus. Together with previous findings, the effect of acute stress on human olfactory perception appears to depend on both the valence and the concentration (e.g., peri-threshold or suprathreshold levels) of odor stimuli.

Caterpillar Responses to Gustatory Stimuli in Potato Tuber Moths: Electrophysiological and Behavioral Insights.

This research investigates how fourth-instar larvae of the potato tuber moth, Phthorimaea operculella, respond to plant secondary metabolites (sucrose, glucose, nicotine, and tannic acid) both in terms of gustatory electrophysiology and feeding behavior. The objective is to establish a theoretical foundation for employing plant-derived compounds in potato tuber moth control. We employed single-sensillum recording techniques and dual-choice leaf disk assays to assess the gustatory electrophysiological responses and feeding preferences of these larvae towards the mentioned compounds. Sensory neurons responsive to sucrose, glucose, nicotine, and tannic acid were identified in the larvae's medial and lateral sensilla styloconica. Neuronal activity was influenced by stimulus type and concentration. Notably, the two types of sensilla styloconica displayed distinct response patterns for sucrose and glucose while they had similar firing patterns towards nicotine and tannic acid. Sucrose and glucose significantly promoted larval feeding, while nicotine and tannic acid had significant inhibitory effects. These findings demonstrate that the medial and lateral sensilla styloconica house sensory neurons sensitive to both feeding stimulants and inhibitors, albeit with differing response profiles and sensitivities. This study suggests that sucrose and glucose are promising candidates for feeding stimulants, while nicotine and tannic acid show potential as effective feeding inhibitors of P. operculella larvae.

Umami taste evaluation based on a novel mouse taste receptor cell-based biosensor

Umami, a taste sensation known for its savory and delicious properties, has garnered considerable attention from both consumers and the food industry. However, current understanding and evaluation of umami characteristics remain limited, presenting a long-standing issue. To address this challenge, we have developed a self-assembled biosensor based on matured taste receptor cells (TRCs), obtained through isolation and culture of taste stem cells. TRCs, as the recognition element, were mounted onto the surface of a glassy carbon electrode (GCE) treated with gold nanoparticles (AuNPs) and poly-L-lysine (PLL). Key parameters including the cell incubation time and concentration were optimized to ensure the optimal performance of the TRCs-based biosensor. AuNPs were deposited onto the GCE surface via 90 s electrochemical reduction. TRCs concentration of 106 cells/mL and incubation time of 12 h were chosen by electrochemical characterization. Using this novel, rapid, and sensitive TRCs-based biosensor, we successfully detected L-monosodium glutamate (MSG) and other umami substances, demonstrating a good linear relationship within the range of 10−9 – 10−5 M between response signals and concentration of MSG stimuli. Our results provide insights into taste signal transduction mechanisms and suggest the potential for biomimetic sensors in intelligent perception applications.

Footwear consumer behavior: The influence of stimuli on emotions and decision making

This paper analyzes the stimuli used in fashion footwear stores to activate emotions and drive consumer purchasing decisions. The efficiency of the stimuli launched in a fashion shoe store was empirically analyzed. The decorative and environmental aspects that generate the highest level of attraction, interest, emotion, and memory in consumers were identified. The study focuses on the use of galvanic skin response and eye tracking to understand consumer preferences in shoe stores. The results reveal the most efficient stimuli. The results also show that the level of saturation of information generated by the concentration of stimuli in retail reduces attention. The described method can be applied to shopping situations without the need for questionnaires.

Alternative splicing: transcriptional regulatory network in agroforestry.

Alternative splicing (AS) in plants plays a key role in regulating the expression of numerous transcripts from a single gene in a regulatory pathway. Variable concentrations of growth regulatory hormones and external stimuli trigger alternative splicing to switch among different growth stages and adapt to environmental stresses. In the AS phenomenon, a spliceosome causes differential transcriptional modifications in messenger RNA (mRNAs), resulting in partial or complete retention of one or more introns as compared to fully spliced mRNA. Differentially expressed proteins translated from intron-retaining messenger RNA (mRNAir) perform vital functions in the feedback mechanism. At the post-transcriptional level, AS causes the remodeling of transcription factors (TFs) by the addition or deletion of binding domains to activate and/or repress transcription. In this study, we have summarized the specific role of AS in the regulation of gene expression through repression and activation of the transcriptional regulatory network under external stimuli and switch among developmental stages.

Boundedness and asymptotic behavior in a quasilinear two-species chemotaxis system with loop

Chemotaxis is the directed movement of cells or organisms in response to the gradients of concentration of the chemical stimuli, plays essential roles in various biological process. In this paper, we consider a quasilinear two-species chemotaxis-competition system with loop in higher dimensions defined on a smooth bounded domain with homogeneous Neumann boundary conditions. With the help of suitable energy functional and some estimates, we obtain the global existence and boundedness of the classical solution of the model, and also show the large time behavior and convergence rate of the solution. Our results show that the nonlinear diffusion mechanism has an inhibitory effect on the blow-up of solution and partially generalized some results in the literature.

The effect of receptor interaction on the bacterial chemotactic adaptation rate

Different receptors have evolved in organisms to sense different stimuli in their surroundings. The interaction among the receptors can significantly increase sensory sensitivity and adaptation precision. To study the influence of interaction among different types of chemoreceptors on the adaptation rate in the bacterial chemotaxis signaling network, we systematically compared the adaptation time between the wild-type strain expressing mixed types of receptors and the mutant strain expressing only Tar receptors (namely, the Tar-only strain) under stepwise addition of different concentrations of L-aspartate using FRET (Förster resonance energy transfer) and bead assays. We find that the wild type exhibits faster adaptation than the mutant under the same concentration of saturated stimulus. In contrast, the wild type exhibits slower adaptation than the mutant under unsaturated stimuli that induce the same magnitude of response, and this is independent of the level of receptor expression. The same result is obtained for the network relaxation time by monitoring the steady-state rotational signal of the flagellar motors. By simulating bacterial chemotaxis with different adaptation rates in a stable gradient of chemoattractants, we confirm that the interaction of different types of receptors can effectively promote chemotaxis of <i>Escherichia coli</i> under a stable spatial gradient of attractants while ensuring minimum noise in the cell position distribution.

AKTs do not translocate to the nucleus upon stimulation but AKT3 can constitutively signal from the nuclear envelope.

AKT is a central signaling protein kinase that plays a role in the regulation of cellular survival metabolism and cell growth, as well as in pathologies such as diabetes and cancer. Human AKT consists of three isoforms (AKT1-3) that may fulfill different functions. Here, we report that distinct subcellular localization of the isoforms directly influences their activity and function. AKT1 is localized primarily in the cytoplasm, AKT2 in the nucleus, and AKT3 in the nucleus or nuclear envelope. None of the isoforms actively translocates into the nucleus upon stimulation. Interestingly, AKT3 at the nuclear envelope is constitutively phosphorylated, enabling a constant phosphorylation of TSC2 at this location. Knockdown of AKT3 induces moderate attenuation of cell proliferation of breast cancer cells. We suggest that in addition to the stimulation-induced activation of the lysosomal/cytoplasmic AKT1-TSC2 pathway, a subpopulation of TSC2 is constitutively inactivated by AKT3 at the nuclear envelope of transformed cells.

A study on the relationship between odor hedonic ratings and individual odor detection threshold

Odor hedonic perception (pleasant/unpleasant character) is considered as the first and one of the most prominent dimensions in olfaction and is known to depend on several parameters. Among them, the relation between the odorant concentration and the hedonic estimation has been widely studied. However, few studies have considered odor hedonic ratings (OHR) in relation to individual detection thresholds (IDT). Thus, the aim of this study was to determine olfactory detection thresholds and to describe hedonic rating variations from individual thresholds to higher concentrations. IDT were performed for two pleasant (apple and jasmine) and two unpleasant (durian and trimethylamine) odorant stimuli. The experimenter presented one by one in a randomized order, the different odorant concentrations above IDT. Participants rated odor hedonic valence of these stimuli on a visual analog scale. Results showed, except for trimethylamine, the same relationship between hedonic ratings and stimulus concentration, i.e., an increase of pleasantness (apple and jasmine)/unpleasantness (durian) ratings at low and middle concentrations followed by a plateau at high concentrations. Correlations between OHR and concentrations as well as between OHR and threshold steps were always significant. Moreover, comparisons between both conditions showed that the correlation coefficient was significantly higher for trimethylamine (and a trend for apple) when IDTs were considered, while no difference was found for jasmine and durian. Overall, results suggested that the relationship between OHR and IDT is odor specific. These findings contribute to explain the large variability of the hedonic tone (i.e., weakly vs. very pleasant, weakly vs. very unpleasant) at specific concentration in the general population and could serve future research in this field (e.g., olfactory preferences in nutrition studies, anhedonia in psychiatric disorders…).

The microglial endocannabinoid system is similarly regulated by lipopolysaccharide and interferon gamma

Perturbation of the endocannabinoid system can have profound effects on immune function and synaptic plasticity. Microglia are one of few cell types with a self-contained endocannabinoid system and are positioned at the interface between the immune system and the central nervous system. Past work has produced conflicting results with respect to the effects of pro-inflammatory conditions on the microglial endocannabinoid system. Thus, we systematically investigated the relationship between the concentration of two distinct pro-inflammatory stimuli, lipopolysaccharide and interferon gamma, on the abundance of components of the endocannabinoid system within microglia. Here we show that lipopolysaccharide and interferon gamma influence messenger RNA abundances of the microglial endocannabinoid system in a concentration-dependent manner. Furthermore, we demonstrate that the efficacy of different synthetic cannabinoid treatments with respect to inhibition of microglia nitric oxide release is dependent on the concentration and type of pro-inflammatory stimuli presented to the microglia. This indicates that different pro-inflammatory stimuli influence the capacity of microglia to synthesize, degrade, and respond to cannabinoids which has implications for the development of cannabinoid-based treatments for neuroinflammation.

Physiological levels of fluid shear stress modulate vascular function through TRPV4 sparklets.

Endothelial calcium (Ca 2+) signaling plays a major role in regulating vasodilation in response to fluid shear stress (FSS) generated by blood flow. Local Ca 2+ influx through single transient receptor potential channel subfamily V member 4 (TRPV4) (termed "sparklets") activated by low concentrations of chemical and biological stimuli has been revealed to modulate vascular function. However, the range in which FSS can initiate TRPV4 sparklets to induce vasodilation is unknown. Here, we assess the activity of TPRV4 sparklets induced by various physiological levels of FSS and investigate the mechanisms involving these Ca 2+ signals in FSS-induced vasodilation. Intact small mesenteric arteries are used for Ca 2+ imaging with a GCaMP2(TRPV4-KO) mouse model and high-speed confocal systems. Markedly increased local Ca 2+ signals are observed in the endothelium under 4-8 dyne/cm 2 FSS, whereas FSS >8 dyne/cm 2 causes global Ca 2+ influx. Further analysis shows that TRPV4 channels form a four-channel group to mediate Ca 2+ sparklets under certain levels of FSS. The large Ca 2+ influx hyperpolarizes endothelial cells by stimulating intermediate (IK)- and small (SK)-conductance Ca 2+-sensitive potassium channels, leading to hyperpolarization of the surrounding smooth muscle cells and ultimately causing endothelium-dependent vasodilation. In conclusion, Ca 2+ influx transits through a small number of endothelial TRPV4 channels opened by certain levels of FSS, which activates the Ca 2+-sensitive IK and SK channels to cause vasodilation.

Which Videofluoroscopy Parameters Are Susceptible to the Influence of Differences in Barium Product and Concentration?

Prior studies suggest there may be differences in videofluoroscopic measures of swallowing across different barium concentrations. Whether different barium products of identical concentration result in similar swallowing physiology remains unknown. This is important, as barium intended for videofluoroscopy (i.e., Bracco Varibar) is not available globally. Our aim was to identify differences in healthy swallowing across five different barium stimuli. Twenty healthy adults (10 women), aged 22-54 years, underwent videofluoroscopy including comfortable sips of thin liquid barium: two sips of 20% weight-to-volume (w/v) barium prepared with E-Z-HD powder, and two sips each of 20%w/v and 40%w/v barium prepared with Liquid Polibar Plus and E-Z-Paque powder. Recordings were analyzed according to the Analysis of Swallowing Physiology: Events, Kinematics and Timing Method. Measures of timing, kinematics and residue were obtained. Chi-square, Friedman's, and Wilcoxon signed-ranks test were used to identify differences across stimuli. Significant differences were seen across barium stimuli for upper esophageal sphincter (UES) opening duration, UES diameter, pharyngeal area at maximum constriction, and residue. In all cases, smaller values were seen with the 20%w/v E-Z-HD stimulus; however, this stimulus had questionable opacity for visualization. Patterns of residue severity were not explained by barium concentration. This study confirms that some measures of swallowing are influenced by barium product and/or concentration. Measures are not necessarily similar across different barium products at the same concentration. This study illustrates the importance of using standard and appropriate stimuli in videofluoroscopy, and for clinicians to report not only the product but also the concentration of stimuli used. https://doi.org/10.23641/asha.20669712.

Kinetic Changes in B7 Costimulatory Molecules and IRF4 Expression in Human Dendritic Cells during LPS Exposure.

A key aspect of the inflammatory phenomenon is the involvement of costimulatory molecules expressed by antigen-presenting cells (APCs) and their ability to secrete cytokines to set instructions for an adaptive immune response and to generate tolerance or inflammation. In a novel integrative approach, we aimed to evaluate the kinetic expression of the membrane and soluble B7 costimulatory molecules CD86, ICOS-L, PDL1, PDL2, the transcription factor Interferon Regulatory Factor 4 (IRF4), and the cytokines produced by monocyte-derived dendritic cells (Mo-DCs) after challenging them with different concentrations of stimulation with E. coli lipopolysaccharide (LPS) for different lengths of time. Our results showed that the stimuli concentration and time of exposure to an antigen are key factors in modulating the dynamic expression pattern of membrane and soluble B7 molecules and cytokines.

Calcium imaging in intact mouse acinar cells in acute pancreas tissue slices.

The physiology and pathophysiology of the exocrine pancreas are in close connection to changes in intra-cellular Ca2+ concentration. Most of our knowledge is based on in vitro experiments on acinar cells or acini enzymatically isolated from their surroundings, which can alter their structure, physiology, and limit our understanding. Due to these limitations, the acute pancreas tissue slice technique was introduced almost two decades ago as a complementary approach to assess the morphology and physiology of both the endocrine and exocrine pancreas in a more conserved in situ setting. In this study, we extend previous work to functional multicellular calcium imaging on acinar cells in tissue slices. The viability and morphological characteristics of acinar cells within the tissue slice were assessed using the LIVE/DEAD assay, transmission electron microscopy, and immunofluorescence imaging. The main aim of our study was to characterize the responses of acinar cells to stimulation with acetylcholine and compare them with responses to cerulein in pancreatic tissue slices, with special emphasis on inter-cellular and inter-acinar heterogeneity and coupling. To this end, calcium imaging was performed employing confocal microscopy during stimulation with a wide range of acetylcholine concentrations and selected concentrations of cerulein. We show that various calcium oscillation parameters depend monotonically on the stimulus concentration and that the activity is rather well synchronized within acini, but not between acini. The acute pancreas tissue slice represents a viable and reliable experimental approach for the evaluation of both intra- and inter-cellular signaling characteristics of acinar cell calcium dynamics. It can be utilized to assess many cells simultaneously with a high spatiotemporal resolution, thus providing an efficient and high-yield platform for future studies of normal acinar cell biology, pathophysiology, and screening pharmacological substances.

Time-Dependent Odorant Sensitivity Modulation in Insects.

Simple SummaryInsects, including blood-feeding female mosquitoes, can transmit deadly diseases, such as malaria, encephalitis, dengue, and yellow fever. Insects use olfaction to locate food sources, mates, and hosts. The nature of odorant plumes poses a challenge for insects in locating odorant sources in the environment. In order to modulate the system for the detection of fresh stimuli or changes in odorant concentrations, the olfaction system desensitizes to different concentrations and durations of stimuli. Without this ability, the chemotaxis behaviors of insects are defective. Thus, understanding how insects adjust their olfactory response dynamics to parse the chemical language of the external environment is not only a basic biology question but also has far-reaching implications for repellents and pest control. Insects use olfaction to detect ecologically relevant chemicals in their environment. To maintain useful responses over a variety of stimuli, olfactory receptor neurons are desensitized to prolonged or high concentrations of stimuli. Depending on the timescale, the desensitization is classified as short-term, which typically spans a few seconds; or long-term, which spans from minutes to hours. Compared with the well-studied mechanisms of desensitization in vertebrate olfactory neurons, the mechanisms underlying invertebrate olfactory sensitivity regulation remain poorly understood. Recently, using a large-scale functional screen, a conserved critical receptor phosphorylation site has been identified in the model insect Drosophila melanogaster, providing new insight into the molecular basis of desensitization in insects. Here, we summarize the progress in this area and provide perspectives on future directions to determine the molecular mechanisms that orchestrate the desensitization in insect olfaction.

Single components of complex chemical signals convey sex identity and individual variation

Chemical signals, such as those used in social communication, are often present as complex blends of compounds, suggesting that complexity is important in signal perception. Very few studies, however, have examined the interactions between different components of complex signals in social signalling. In the Mysore day gecko, Cnemaspis mysoriensis , secretions of males are sufficient to elicit a behavioural response in females and these male secretions differ from those of females in the presence of two key chemical compounds: cholesterol and squalene. This provided us with an opportunity to determine the functions and interactions of individual components in a complex multicomponent chemical signal. First, using tongue flick assays, we established that both components independently elicit a behavioural response in females, but not males. When presented as a multicomponent mix, the response levels of females were similar to those shown towards the individual components, thereby indicating that cholesterol and squalene are redundant components. Moreover, female responses towards these components matched their level of response towards natural male secretions, confirming that both cholesterol and squalene signal sex identity of males. When presented with a gradient of multicomponent stimulus concentrations, females, but not males, incrementally adjusted their tongue flick responses to different levels. Further, responses of females were similar regardless of whether cholesterol or squalene was at a higher relative concentration in the multicomponent stimulus. These last two sets of results indicate that the overall concentration, but not the relative ratio of cholesterol and squalene, has the potential to encode information about male quality. Lack of responses by males to these compounds across experiments strongly indicate the role of cholesterol and squalene in intersexual, and not intrasexual, communication. Overall, we show that two sex-specific compounds in a complex multicomponent chemical signal are effective in communicating complex sexual information from males to conspecific females. • Chemical signals in males of Cnemaspis mysoriensis contain cholesterol and squalene. • Only females respond to these compounds, in ways that indicate redundancy. • Cholesterol and squalene are independently effective sex identity signals. • Dose-dependent responses indicate potential for these to be mate assessment signals.