Emotional responses to pleasant and unpleasant oral flavour stimuli

The hedonic valence of taste perception plays a crucial role in the control of responses related to feeding behaviour. Taste and olfaction perception can induce autonomic responses, such as heart rate variability (HRV), which are involved in the evoked emotional reactions. Analysis of HRV can help distinguish sympathetic from parasympathetic regulation of the sinoatrial node. In this work, we analysed the HRV associated with oral flavour stimuli with opposite hedonic dimension and assessed their sympathovagal balance. ECGs were recorded continuously on 11 men and 12 women before and after stimulations. Experiments were performed in two sessions for comparison. ANOVA highlighted the decreases and increases of sinusal rhythm associated with pleasant and unpleasant flavour stimulations, respectively. Time and frequency domain analysis of HRV indicates that bradycardia induced by the pleasant stimulus can be attributed to an increase in the vagal tone, whilst tachycardia evoked by the unpleasant stimulus denotes a reduction of the vagal tone in women and an increase of the sympathetic tone in men. In conclusion, our data suggest that the HRV analysis may represent a valuable tool for autonomic nervous system response characterization associated to the hedonic dimension of the complex flavour sensations induced by food and/or beverages. © Springer Science+Business Media, LLC 2011

A method for selective stimulation of leg chemoreceptors in whole crustaceans

The integration of sensory information with adequate motor outputs is critical for animal survival. Here, we present an innovative technique based on a non-invasive closed-circuit device consisting of a perfusion/stimulation chamber chronically applied on a single leg of the crayfish Procambarus clarkii. Using this technique, we focally stimulated the leg inside the chamber and studied the leg-dependent sensory-motor integration involving other sensory appendages, such as antennules and maxillipeds, which remain unstimulated outside the chamber. Results show that the stimulation of a single leg with chemicals, such as disaccharides, is sufficient to trigger a complex search behaviour involving locomotion coupled with the reflex activation of antennules and maxillipeds. This technique can be easily adapted to other decapods and/or other sensory appendages. Thus, it has opened possibilities for studying sensory-motor integration evoked by leg stimulation in whole aquatic animals under natural conditions to supplement, with a direct approach, current ablation/silencing techniques

Blue-Green Algae as Stimulating and Attractive Feeding Substrates for a Mediterranean Commercial Sea Urchin Species, Paracentrotus lividus

Sea urchins rely on chemical senses to localize suitable food resources, therefore representing model species for chemosensory studies. In the present study, we investigated the chemical sensitivity of the Mediterranean sea urchin Paracentrotus lividus to the blue-green alga Aphanizomenon flos-aquae, namely "Klamath", and to a few amino acids chosen from the biochemical composition of the same algae. To this end, we used the "urchinogram" method, which estimates the movement rate of the sea urchins in response to chemicals. Our results showed that Klamath represents a strong chemical stimulus for P. lividus as it elicits an overall movement of spines, pedicellariae, and tube feet coupled, in some cases, to a coordinated locomotion of the animals. Sea urchins also displayed a sensitivity, even if to a lesser extent, to leucine, threonine, arginine, and proline, thus implying that the amino acids contained in Klamath may account, at least in part, for the stimulating effects exerted by the whole algae. Additionally, our results show that Klamath, as well as spirulina, another blue-green alga with high nutritional value, is very attractive for this sea urchin species. These findings gain further importance considering the potential profit of echinoderms for commercial consumers and their growing role in aquaculture. Klamath and spirulina combine high nutritional profiles with attractive and stimulating abilities and may be considered potential valuable feed supplements in sea urchin aquaculture

Chemosensitivity in the Sea Urchin Paracentrotus lividus (Echinodermata: Echinoidea) to Food-Related Compounds: An Innovative Behavioral Bioassay

Like other animals, echinoderms rely on chemical senses to detect and localize food resources. Here, we evaluate the chemical sensitivity of the sea urchin Paracentrotus lividus to a number of stimuli possibly related to food, such as a few sugars, compared to the blue-green algae Spirulina (Arthrospira platensis). To do this we developed a simple, innovative method based on the recording of “urchinograms” estimating the movements of spines, pedicellariae, tube feet, and eventually of the whole sea urchin, in response to chemicals, while keeping both the whole animal and the stimulus in their natural environment, underwater. Our results show that Spirulina is a highly stimulating compound for the sea urchin, by acting in a dose-dependent manner. The animals resulted also sensitive, even if to a lesser extent, to some sugars, such as the monosaccharide glucose, but not to its isomer fructose, while among disaccharides, they sensed cellobiose, but not sucrose or trehalose. From an applied point of view, any insight into the chemical sensitivity of sea urchins toward potential food-related compounds may lead to the discovery of key chemicals that would help improve the efficiency and reduce the costs of dietary substrates for optimization of intensive rearing strategies. Although this method has been developed for P. lividus, it will be suitable to evaluate the chemical sensitivity of other echinoderms and other marine invertebrates characterized by low mobility

EAG responses to pheromone as a tool in the control of population dynamics of the gypsy moth <i>Lymantria dispar</i>

The reproductive programme of the gypsy moth Lymantria dispar L. (Lepidoptera: Lymantriidae), the most important defoliator of Sardinian Quercus suber L. forests, is based on production and release of its sex pheromone (+)disparlure by calling female moths and its perception by conspecific males. The acquisition of information about any factors influencing male sensitivity to this sex attractant may help improve field techniques against this defoliator or possibly provide a basis for predicting where favourable conditions for control of population dynamics will occur. In this respect, the pheromone might be used as a specific tool for olfaction research and to monitor changes in male sensitivity, thus leading to a better control of population

Chemosensory Receptors in the Larval Maxilla of Papilio hospiton

Among the butterflies of the genus Papilio (Lepidoptera: Papilionidae), Papilio hospiton (Gene) has a geographical distribution limited to the Mediterranean islands of Sardinia (Italy) and Corsica (France). This is mainly due to the host range that includes only a few plant species of Apiaceae and Rutaceae growing on these islands. In a previous electrophysiological investigation conducted on the maxillary gustatory system of larvae of P. hospiton and its closely phylogenetically related species Papilio machaon, a significantly higher spike activity was shown for the gustatory neurons of lateral and medial styloconic sensilla in P. hospiton when bitter compounds were tested. This effect was possibly correlated to the limited host choice range for P. hospiton. To shed light on the molecular aspects of this phenomenon, we investigated the expression pattern of sensory-related sequences by conducting a transcriptomic analysis from total RNA isolates of P. hospiton larval maxillae. We identified several transcripts that may be involved in taste (one gustatory receptor, one divergent ionotropic receptor, and several transient receptor potential channels, TRPs) as well as transcripts supporting an olfactory function for this appendage, including odorant receptors (ORs), antennal ionotropic receptors (A-IRs), sensory neuron membrane proteins (SNMPs), and odorant-binding proteins (OBPs). We used Human Embryonic Kidney (HEK293A) cells to heterologously express two of the identified receptors, PhospOR1 and PhospPain, together with their orthologs from P. machaon, for functional characterization. While our data suggest no activation of these two receptors by the ligands known so far to activate the electrophysiological response in larval maxillary neurons of Papilio species, nor temperature activation of both Papilio TRPA-channel Painless, they represent the first attempt in connecting neuronal activity with their molecular bases to unravel diet specialization between closely related Papilio species

Chemosensory Receptors in the Larval Maxilla of Papilio hospiton

Among the butterflies of the genus Papilio (Lepidoptera: Papilionidae), Papilio hospiton (Géné) has a geographical distribution limited to the Mediterranean islands of Sardinia (Italy) and Corsica (France). This is mainly due to the host range that includes only a few plant species of Apiaceae and Rutaceae growing on these islands. In a previous electrophysiological investigation conducted on the maxillary gustatory system of larvae of P. hospiton and its closely phylogenetically related species Papilio machaon, a significantly higher spike activity was shown for the gustatory neurons of lateral and medial styloconic sensilla in P. hospiton when bitter compounds were tested. This effect was possibly correlated to the limited host choice range for P. hospiton. To shed light on the molecular aspects of this phenomenon, we investigated the expression pattern of sensory-related sequences by conducting a transcriptomic analysis from total RNA isolates of P. hospiton larval maxillae. We identified several transcripts that may be involved in taste (one gustatory receptor, one divergent ionotropic receptor, and several transient receptor potential channels, TRPs) as well as transcripts supporting an olfactory function for this appendage, including odorant receptors (ORs), antennal ionotropic receptors (A-IRs), sensory neuron membrane proteins (SNMPs), and odorant-binding proteins (OBPs). We used Human Embryonic Kidney (HEK293A) cells to heterologously express two of the identified receptors, PhospOR1 and PhospPain, together with their orthologs from P. machaon, for functional characterization. While our data suggest no activation of these two receptors by the ligands known so far to activate the electrophysiological response in larval maxillary neurons of Papilio species, nor temperature activation of both Papilio TRPA-channel Painless, they represent the first attempt in connecting neuronal activity with their molecular bases to unravel diet specialization between closely related Papilio species

The gustin (CA6) gene polymorphism, rs2274333 (A/G), is associated with fungiform papilla density, whereas PROP bitterness is mostly due to TAS2R38 in an ethnically-mixed population

PROP responsiveness is associated with TAS2R38 haplotypes and fungiform papilla density. Recently, we showed that a polymorphism in the gene coding for the salivary trophic factor, gustin (CA6), affects PROP sensitivity by acting on cell growth and fungiform papillae maintenance, in a genetically homogeneous cohort. Since population homogeneity can lead to over estimation of gene effects, the primary aim of the present work was to confirm gustin’s role in PROP bitterness intensity and fungiform papillae density in a genetically diverse population. Eighty subjects were genotyped for both genes by PCR techniques. PROP responsiveness was assessed by filter paper method and fungiform papilla density was determined in each subject. As expected, PROP bitterness ratings were lower in individuals with the AVI/AVI diplotype of TAS2R38 than in individuals with PAV/PAV and PAV/AVI diplotype. However, no differences in PROP bitterness among genotypes of the gustin gene, and no differences in the density of fungiform papillae related to TAS2R38 diplotype were found. In contrast, the density of fungiform papillae decreased as the number of minor (G) alleles at the gustin locus increased. In addition, the distribution of TAS2R38 genotypes within each gustin genotype group showed that the occurrence of recessive alleles at both loci was infrequent in the present sample compared to other populations. These findings confirm that papillae density is associated with gustin gene polymorphism, rs2274333 (A/G), in an ancestrally heterogeneous population, and suggest that variations in the frequency of allele combinations for these two genes could provide a salient explanation for discrepant findings for gustin gene effects across population

Olfactory Function in Patients with Inflammatory Bowel Disease (IBD) Is Associated with Their Body Mass Index and Polymorphism in the Odor Binding Protein (OBPIIa) Gene

Smell strongly contributes to food choice and intake, influencing energy balance and body weight; its reduction or loss has been related to malnutrition problems. Some patients with inflammatory bowel disease (IBD), mainly Crohn’s disease (CD) and ulcerative colitis (UC), are underweight, while others are overweight. Some studies suggest that changes in eating habits could be linked to specific disorders of the olfactory functions. We assessed the olfactory performance in 199 subjects (healthy control (HC) n = 99, IBD n = 100), based on the olfactory Threshold, Discrimination and Identification score (TDI score), measured with the “Sniffin’ Sticks” test. Subjects were genotyped for the rs2590498 polymorphism of the OBPIIa gene. IBD patients showed both a slightly, but significantly, lower olfactory function and a higher BMI compared to HC subjects. Threshold (in both population) and Discrimination (in IBD patients) olfactory score were affected by the OBPIIa genotype. BMI was influenced by both health status and OBPIIa genotype. A lower olfactory function may delay the satiety sensation and thus increase meal duration and body weight in IBD patients. However, the AA genotype of the OBPIIa seems to “protect” IBD patients from more severe olfactory dysfunction

Analoghi di sintesi del feromone sessuale come strumento per il controllo della popolazione di <i>Lymantria dispar</i>

La strategia riproduttiva delle farfalle notturne è basata sull’utilizzo di un feromone speciespecifico, prodotto dagli esemplari femminili per il richiamo a lunga distanza degli individui maschi conspecifici. In particolare le femmine di Lymantria dispar, uno dei più importanti insetti fitofagi defogliatori delle sugherete sarde, elaborano un feromone costituito da un unico componente, chiamato (+)disparlure (2-methyl-7,8-epoxy-octadecane) e lo accumulano nella ghiandola del feromone fino al rilascio. Nel presente lavoro abbiamo sintetizzato diversi analoghi del feromone naturale, allo scopo di ottenere molecole con un maggiore potere attrattivo sugli esemplari maschili, o più stabili nel tempo, ossia dotate di tempi di decadimento più lunghi