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PubMed1989

A test of the Easterlin fertility model using income for two generations and a comparison with the Becker model.

An important dimension of Easterlin's seminal work on fertility is the hypothesis of intergenerational taste formation, or the relative income hypothesis. Previous estimates have not had data on income in two generations, so the estimated own-income effects may have had a downward bias. This article uses data with income from two generations to estimate the Easterlin model directly. Own income is still not positively significant. A simple single-equation test is developed to distinguish this model from a Becker intergenerational serially correlated endowments model that he claims is observationally equivalent. The test results favor the Becker formulation.

Female↗
PubMed2003

Channels as taste receptors in vertebrates.

Taste reception is fundamental for proper selection of food and beverages. Chemicals detected as taste stimuli by vertebrates include a large variety of substances, ranging from inorganic ions (e.g., Na(+), H(+)) to more complex molecules (e.g., sucrose, amino acids, alkaloids). Specialized epithelial cells, called taste receptor cells (TRCs), express specific membrane proteins that function as receptors for taste stimuli. Classical view of the early events in chemical detection was based on the assumption that taste substances bind to membrane receptors in TRCs without permeating the tissue. Although this model is still valid for some chemicals, such as sucrose, it does not hold for small ions, such as Na(+), that actually diffuse inside the taste tissue through ion channels. Electrophysiological, pharmacological, biochemical, and molecular biological studies have provided evidence that indeed TRCs use ion channels to reveal the presence of certain substances in foodstuff. In this review, we focus on the functional and molecular properties of ion channels that serve as receptors in taste transduction.

Animals↗
PubMed2005

Tasting the difference: do multiple defence chemicals interact in Müllerian mimicry?

Müllerian mimicry, where two unpalatable species share a warning pattern, is classically believed to be a form of mutualism, where the species involved share the cost of predator education. The evolutionary dynamics of Müllerian mimicry have recently become a controversial subject, after mathematical models have shown that if minor alterations are made to assumptions about the way in which predators learn and forget about unpalatable prey, this textbook case of mutualism may not be mutualistic at all. An underlying assumption of these models is that Müllerian mimics possess the same defence chemical. However, some Müllerian mimics are known to possess different defence chemicals. Using domestic chicks as predators and coloured crumbs flavoured with either the same or different unpalatable chemicals as prey, we provide evidence that two defence chemicals can interact to enhance predator learning and memory. This indicates that Müllerian mimics that possess different defence chemicals are better protected than those that share a single defence chemical. These data provide insight into how multiple defence chemicals are perceived by birds,and how they influence the way birds learn and remember warningly coloured prey. They highlight the importance of considering how different toxins in mimicry rings can interact in the evolution and maintenance of Müllerian mimicry and could help to explain the remarkable variation in chemical defences found within and between species.

Adaptation, Physiological↗
PubMed1980

The taste aversion induction properties of two long duration barbiturates.

The ability of sodium phenobarbital (60 mg/kg) and sodium barbital (80 mg/kg) to produce a taste aversion in 23 hr fluid deprived rats was examined using a discrimination or two bottle taste aversion task (0.125% sodium saccharin solution or water). The interaction of both barbiturates with the effects of 3.0 mEq/kg lithium chloride (LiCl) was also examined. Results indicate that phenobarbital treatment alone produces a stronger saccharin aversion than does barbital. Also, barbiturate treatment 24 hr after LICi administration does not attenuate saccharin avoidance, although phenobarbital treatment following LiCl administration was sufficient to induce a maximum aversion that did not extinguish after twenty days of continuous discrimination testing. These data suggest that the aversion inducing properties of the two barbiturates are dissimilar and that phenobarbital is the more effective agent in the production of saccharin aversion. In addition, barbiturate induced attenuation of conditioned taste aversion is apparently related to the periodic forced intake test model since it does not occur when a water and saccharin choice is available.

Animals↗
PubMed2002

Electrogustometric thresholds: relationship to anterior tongue locus, area of stimulation, and number of fungiform papillae.

It is well established that, on the anterior tongue, thresholds for chemical tastants are inversely related to the number of fungiform papillae. However, it is not known whether this is the case for thresholds for electrical currents presented to the lingual surface. In this study, electrical thresholds for 16 subjects were determined at four left-side anterior lingual locations: tongue tip (TT), a region 1.7 cm posterior to the TT, a region 3.4 cm posterior to the TT, and a region 1.7 cm from the TT along the lateral margin. Two electrode sizes (12.5 mm2 and 50 mm2) were employed for the anodal current, and stimulus duration was held constant at 0.5 s. The number of fungiform papillae was determined using videomicroscopy. Analogous to what is seen with chemical stimulation, an inverse relationship was present between the mean electrical thresholds, expressed in terms of current density, and the number of papillae within the stimulated regions. The TT-which has the highest density of fungiform papillae--was found to be more sensitive than the other tongue regions evaluated. Also paralleling chemical thresholds, the mean electrical threshold values were lower (i.e., sensitivity was higher) at a given tongue locus for the 50-mm2 than for the 12.5-mm2 stimulus area. Overall, this study demonstrates that thresholds for electrical stimulation vary across discrete regions of the anterior tongue and are specifically related to the number of fungiform papillae within the stimulated regions. These observations provide additional support for the hypothesis that lingual sensations induced by low levels of electrical current are mediated by the taste system.

Adolescent↗
PubMed2000

Taste active compounds in a goat cheese water-soluble extract. 2. Determination of the relative impact of water-soluble extract components on its taste using omission tests.

The aim of this work was to determine the relative impact of water-soluble compounds on the gustatory properties of a goat cheese water-soluble extract (WSE). Using a semisynthetic model mixture (MWSE) previously elaborated in physicochemical and gustatory accordance with the cheese WSE (see part 1, Engel et al. J. Agric. Food Chem. 2000, 48, 4252-4259), omission tests were performed. Among the main taste characteristics of the WSE (salty, sour, and bitter), saltiness was explained by an additive contribution of sodium, potassium, calcium, and magnesium cations, whereas sourness was mainly due to a synergistic effect involving sodium chloride, phosphates, and lactic acid and bitterness was found to result from calcium and magnesium chlorides, the impact of which was partially masked by sodium chloride. In contrast, amino acids, lactose, and peptides did not have any significant impact on WSE taste properties. To quantify the contribution of the taste active compounds to bitterness and saltiness, stepwise multiple linear regressions were performed. Those contributions were expressed as a percentage of the considered taste characteristic intensity in the WSE. The model obtained allowed up to 97.4% of the perceived saltiness to be described and approximately 85% of the bitterness.

Animals↗
PubMed1994

The organization of the chemosensory system in Drosophila melanogaster: a review.

This review surveys the organization of the olfactory and gustatory systems in the imago and in the larva of Drosophila melanogaster, both at the sensory and the central level. Olfactory epithelia of the adult are located primarily on the third antennal segment (funiculus) and on the maxillary palps. About 200 basiconic (BS), 150 trichoid (TS) and 60 coeloconic sensilla (CS) cover the surface of the funiculus, and an additional 60 BS are located on the maxillary palps. Males possess about 30% more TS but 20% fewer BS than females. All these sensilla are multineuronal; they may be purely olfactory or multimodal with an olfactory component. Antennal and maxillary afferents converge onto approximately 35 glomeruli within the antennal lobe. These projections obey precise rules: individual fibers are glomerulus-specific, and different types of sensilla are associated with particular subsets of glomeruli. Possible functions of antennal glomeruli are discussed. In contrast to olfactory sensilla, gustatory sensilla of the imago are located at many sites, including the labellum, the pharynx, the legs, the wing margin and the female genitalia. Each of these sensory sites has its own central target. Taste sensilla are usually composed of one mechano- and three chemosensory neurons. Individual chemosensory neurons within a sensillum respond to distinct subsets of molecules and project into different central target regions. The chemosensory system of the larva is much simpler and consists essentially of three major sensillar complexes on the cephalic lobe, the dorsal, terminal and ventral organs, and a series of pharyngeal sensilla.

Animals↗
PubMed1982

Decreased feeding associated with acute hypoxia in rats.

Rats obtained less food than normal on a cyclic-ratio schedule during brief, 1-hr exposure to either moderate hypobaric hypoxia (BP = 435 Torr, PO2 approximately equal to 91 Torr) or to hypoxic hypoxia (BP = 750 Torr, PO2, approximately equal to 90 Torr), but not during hypobaric exposure with 36.5% oxygen (BP = 435 Torr, PO2 approximately equal to 159 Torr). The depressed rate of feeding associated with hypoxia was nevertheless well regulated. Interpreted in terms of a regulatory model, these results suggest that hypoxia suppresses eating because it degrades the taste of food, not because it impairs feeding regulation or general activity.

Altitude↗
PubMed2006

Taste discrimination in conditioned taste aversion of the pond snail Lymnaea stagnalis.

Conditioned taste aversion (CTA) in the pond snail Lymnaea stagnalis has been widely used as a model for gaining an understanding of the molecular and behavioral mechanisms underlying learning and memory. At the behavioral level, however, it is still unclear how taste discrimination and CTA interact. We thus examined how CTA to one taste affected the feeding response induced by another appetitive food stimulus. We first demonstrated that snails have the capacity to recognize sucrose and carrot juice as distinct appetitive stimuli. We then found that snails can become conditioned (i.e. CTA) to avoid one of the stimuli and not the other. These results show that snails can distinguish between appetitive stimuli during CTA, suggesting that taste discrimination is processed upstream of the site where memory consolidation in the snail brain occurs. Moreover, we examined second-order conditioning with two appetitive stimuli and one aversive stimulus. Snails acquired second-order conditioning and were still able to distinguish between the different stimuli. Finally, we repeatedly presented the conditional stimulus alone to the conditioned snails, but this procedure did not extinguish the long-term memory of CTA in the snails. Taken together, our data suggest that CTA causes specific, irreversible and rigid changes from appetitive stimuli to aversive ones in the conditioning procedure.

Animals↗
PubMed2006

Heritability of food preferences in young children.

BACKGROUND: There is persisting interest in the idea that taste preferences are heritable characteristics, but few twin studies have found evidence for a significant genetic component. Small sample sizes and idiosyncratic selection of foods may have contributed to the negative results. We hypothesized that using a larger twin sample and empirical groupings of food types, would give stronger evidence for the heritability of food preferences. OBJECTIVE: We examined the heritability of preferences for four food groups in a sample of young twins. DESIGN: We administered a food preference questionnaire with 95 foods to 214 mothers of same-sex twin pairs (103 monozygotic and 111 dizygotic pairs) aged 4 to 5. 18 foods were excluded because they had been tried by fewer than 25% of the children. Foods were grouped into 'Vegetables', 'Fruits', 'Desserts' and 'Meat and Fish' on the basis of a factor analysis of the preference data. Genetic analyses were carried out on mean liking across these four groups, using model fitting techniques. RESULTS: Over all 77 foods, MZ correlations were higher than DZ correlations for 72 of them, with a higher mean MZ correlation (r = 0.76) than DZ correlation (r = 0.56). Using model fitting techniques with the factor scores, significant heritability estimates were obtained for all four food groups. Heritability was modest for dessert foods (0.20), moderate for vegetables (0.37) and fruits (0.51), and high for liking for protein foods (0.78). Shared environmental effects were strong for desserts, fruits and vegetables, while non-shared environmental influences were low for all four food groups. CONCLUSIONS: These results provide strong evidence for modest heritability of food preferences when using empirically-derived groupings of foods.

Child, Preschool↗
PubMed2004

Spacing patterns on tongue surface-gustatory papilla.

The dorsal surface of the mammalian tongue is covered with four kinds of papillae, fungiform, circumvallate, foliate and filiform papillae. With the exception of the filiform papillae, these types of papillae contain taste buds and are known as the gustatory papillae. The gustatory papillae are distributed over the tongue surface in a distinct spatial pattern. The circumvallate and foliate papillae are positioned in the central and lateral regions respectively and the fungiform papillae are distributed on the anterior part of the tongue in a stereotyped array. The patterned distribution and developmental processes of the fungiform papillae indicate some similarity between the fungiform papillae and the other epithelial appendages, including the teeth, feathers and hair. This is because 1) prior to the morphological changes, the signaling molecules are expressed in the fungiform papillae forming area with a stereotyped pattern; 2) the morphogenesis of the fungiform papillae showed specific structures in early development, such as epithelial thickening and mesenchymal condensation and 3) the fungiform papillae develop through reciprocal interactions between the epithelium and mesenchymal tissue. These results led us to examine whether or not the early organogenesis of the fungiform papillae is a good model system for understanding both the spacing pattern and the epithelial-mesenchymal interaction during embryogenesis.

Animals↗
PubMed1999

Peripheral and central structures involved in insect gustation.

Studies in insect gustation have a long history in general physiology, particularly with work on fly labellar and tarsal sensilla and in the general field of insect-plant interactions, where work on immature Lepidoptera and chrysomelid beetles has been prominent. Much more emphasis has been placed on the physiological characteristics of the sensory cells than on the central cellular mechanisms of taste processing. This is due to the fairly direct access for physiological experimentation presented by many taste sensilla and to the obvious importance of tastants in insect feeding and oviposition behaviour. In some of the insect models used for gustatory studies, advances have been made in understanding the basic morphology of the central neuropils involved in the first stages of taste processing. There is much less known about the physiology of interneurons involved. In this review, we concentrate on four insect models (Manduca sexta, Drosophila melanogaster, Neobellieria bullata (and other large flies), and Apis mellifera) to summarize morphological knowledge of peripheral and central aspects of insect gustation. Our views of current interpretations of available data are discussed and some important areas for future research are highlighted.

Animals↗