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G K Beauchamp

Publications and source records attributed to G K Beauchamp.

At least 19 recordsLinked to original sources
PubMed2001

Soa genotype selectively affects mouse gustatory neural responses to sucrose octaacetate.

In mice, behavioral acceptance of the bitter compound sucrose octaacetate (SOA) depends on allelic variation of a single gene, Soa. The SW.B6-Soa(b)congenic mouse strain has the genetic background of an "SOA taster" SWR/J strain and an Soa-containing donor chromosome fragment from an "SOA nontaster" C57BL/6J strain. Using microsatellite markers polymorphic between the two parental strains, we determined that the donor fragment spans 5-10 cM of distal chromosome 6. The SWR/J mice avoided SOA in two-bottle tests with water and had strong responses to SOA in two gustatory nerves, the chorda tympani (CT) and glossopharyngeal (GL). In contrast, the SW.B6-Soa(b) mice were indifferent to SOA in two-bottle tests and had very weak responses to SOA in both of these nerves. The SWR/J and SW.B6-Soa(b) mice did not differ in responses of either nerve to sucrose, NaCl, HCl, or the bitter-tasting stimuli quinine, denatonium, strychnine, 6-n-propylthiouracil, phenylthiocarbamide, and MgSO(4). Thus the effect of the Soa genotype on SOA avoidance is mediated by peripheral taste responsiveness to SOA, involving taste receptor cells innervated by both the CT and GL nerves.

Animals↗
PubMed2001

High-resolution genetic mapping of the sucrose octaacetate taste aversion (Soa) locus on mouse Chromosome 6.

An acetylated sugar, sucrose octaacetate (SOA), tastes bitter to humans and has an aversive taste to at least some mice and other animals. In mice, taste aversion to SOA depends on allelic variation of a single locus, Soa. Three Soa alleles determine 'taster' (Soa(a)), 'nontaster' (Soa(b)), and 'demitaster' (Soa(c)) phenotypes of taste sensitivity to SOA. Although Soa has been mapped to distal Chromosome (Chr) 6, the limits of the Soa region have not been defined. In this study, mice from congenic strains SW.B6-Soa(b), B6.SW-Soa(a), and C3.SW-Soa(a/c) and from an outbred CFW strain were genotyped with polymorphic markers on Chr 6. In the congenic strains, the limits of introgressed donor fragments were determined. In the outbred mice, linkage disequilibrium and haplotype analyses were conducted. Positions of the markers were further resolved by using radiation hybrid mapping. The results show that the Soa locus is contained in an approximately 1-cM (3.3-4.9 Mb) region including the Prp locus.

Animals↗
PubMed2001

High-resolution genetic mapping of the saccharin preference locus (Sac) and the putative sweet taste receptor (T1R1) gene (Gpr70) to mouse distal Chromosome 4.

The Sac (saccharin preference) locus affecting mouse behavioral and neural responsiveness to sweeteners has been mapped to distal Chr 4. A putative sweet taste receptor, T1R1, has been recently cloned, and the gene encoding it, Gpr70, has also been mapped to mouse distal Chr 4. To assess Gpr70 as a candidate gene for Sac, we compared the Gpr70 sequences of C57BL/6ByJ and 129P3/J mouse strains with different alleles of Sac. Using Gpr70 sequence variation between the C57BL/6ByJ and 129P3/J strains, we conducted a high-resolution analysis of the chromosomal localization of the Gpr70 and Sac loci in the F2 hybrids and 129.B6-Sac partially congenic mice originating from these two strains. The Gpr70 gene maps proximal to Sac, which demonstrates that they are different loci.

Animals↗
PubMed2001

Nutrient preference and diet-induced adiposity in C57BL/6ByJ and 129P3/J mice.

Purified carbohydrates and fats are usually palatable to humans and other animals, and their consumption often induces weight gain and accumulation of fat. In this study, we examined consumption of complex carbohydrates (cornstarch and Polycose) and fats (soybean oil and margarine) in mice from two inbred strains, C57BL/6ByJ and 129P3/J. At lower concentrations of liquid nutrients tested using two-bottle tests, when the amounts consumed had negligible energy content, the C57BL/6ByJ mice had higher acceptance of Polycose and soybean oil. This was probably due to strain differences in chemosensory perception of Polycose and oil. At higher concentrations, the mice consumed a substantial part of their daily energy from the macronutrient sources, however, there were no or only small strain differences in nutrient consumption. These small differences were probably due to strain variation in body size. The two strains also did not differ in chow intake. Despite similar energy intakes, access to the nutrients resulted in greater body weight (BW) gain in the C57BL/6ByJ mice than in the 129P3/J mice. The diet-induced weight gain was examined in detail in groups of 2-month-old C57BL/6ByJ and 129P3/J mice given ether chow, or chow and margarine to eat. Access to margarine did not increase total energy consumption of either strain. It increased BW and adiposity of the C57BL/6ByJ mice, but only after they reached the age of approximately 3 months. There were no differences in BW and adiposity between control and margarine-exposed 129P3/J mice. The results suggest that diet-induced adiposity in the B6 mice depends on age and does not depend on hyperphagia.

Animals↗
PubMed2001

Sweetener preference of C57BL/6ByJ and 129P3/J mice.

Previous studies have shown large differences in taste responses to several sweeteners between mice of the C57BL/6ByJ (B6) and 129P3/J (129) inbred strains. The goal of this study was to compare behavioral responses of B6 and 129 mice to a wider variety of sweeteners. Seventeen sweeteners were tested using two-bottle preference tests with water. Three main patterns of strain differences were evident. First, sucrose, maltose, saccharin, acesulfame-K, sucralose and SC-45647 were preferred by both strains, but the B6 mice had lower preference thresholds and higher solution intakes. Second, the amino acids D-phenylalanine, D-tryptophan, L-proline and glycine were highly preferred by B6 mice, but not by 129 mice. Third, glycyrrhizic acid, neohesperidin dihydrochalcone, thaumatin and cyclamate did not evoke strong preferences in either strain. Aspartame was neutral to all 129 and some B6 mice, but other B6 mice strongly preferred it. Thus, compared with the 129 mice the B6 mice had higher preferences for sugars, sweet tasting amino acids and several but not all non-caloric sweeteners. Glycyrrhizic acid, neohesperidin, thaumatin and cyclamate are not palatable to B6 or 129 mice.

Animals↗
PubMed2001

Whole nerve chorda tympani responses to sweeteners in C57BL/6ByJ and 129P3/J mice.

The C57BL/6ByJ (B6) strain of mice exhibits higher preferences than does the 129P3/J (129) strain for a variety of sweet tasting compounds. We measured gustatory afferent responses of the whole chorda tympani nerve in these two strains using a broad array of sweeteners and other taste stimuli. Neural responses were greater in B6 than in 129 mice to the sugars sucrose and maltose, the polyol D-sorbitol and the non-caloric sweeteners Na saccharin, acesulfame-K, SC-45647 and sucralose. Lower neural response thresholds were also observed in the B6 strain for most of these stimuli. The strains did not differ in their neural responses to amino acids that are thought to taste sweet to mice, with the exception of L-proline, which evoked larger responses in the B6 strain. Aspartame and thaumatin, which taste sweet to humans but are not strongly preferred by B6 or 129 mice, did not evoke neural responses that exceeded threshold in either strain. The strains generally did not differ in their neural responses to NaCl, quinine and HCl. Thus, variation between the B6 and 129 strains in the peripheral gustatory system may contribute to differences in their consumption of many sweeteners.

Animals↗
PubMed2001

Positional cloning of the mouse saccharin preference (Sac) locus.

Differences in sweetener intake among inbred strains of mice are partially determined by allelic variation of the saccharin preference (Sac) locus. Genetic and physical mapping limited a critical genomic interval containing Sac to a 194 kb DNA fragment. Sequencing and annotation of this region identified a gene (Tas1r3) encoding the third member of the T1R family of putative taste receptors, T1R3. Introgression by serial backcrossing of the 194 kb chromosomal fragment containing the Tas1r3 allele from the high-sweetener-preferring C57BL/6ByJ strain onto the genetic background of the low-sweetener-preferring 129P3/J strain rescued its low-sweetener-preference phenotype. Polymorphisms of Tas1r3 that are likely to have functional significance were identified using analysis of genomic sequences and sweetener-preference phenotypes of genealogically distant mouse strains. Tas1r3 has two common haplotypes, consisting of six single nucleotide polymorphisms: one haplotype was found in mouse strains with elevated sweetener preference and the other in strains relatively indifferent to sweeteners. This study provides compelling evidence that Tas1r3 is equivalent to the Sac locus and that the T1R3 receptor responds to sweeteners.

Alleles↗
PubMed2001

Prenatal and postnatal flavor learning by human infants.

BACKGROUND: Flavors from the mother's diet during pregnancy are transmitted to amniotic fluid and swallowed by the fetus. Consequently, the types of food eaten by women during pregnancy and, hence, the flavor principles of their culture may be experienced by the infants before their first exposure to solid foods. Some of these same flavors will later be experienced by infants in breast milk, a liquid that, like amniotic fluid, comprises flavors that directly reflect the foods, spices, and beverages eaten by the mother. The present study tested the hypothesis that experience with a flavor in amniotic fluid or breast milk modifies the infants' acceptance and enjoyment of similarly flavored foods at weaning. METHODS: Pregnant women who planned on breastfeeding their infants were randomly assigned to 1 of 3 groups. The women consumed either 300 mL of carrot juice or water for 4 days per week for 3 consecutive weeks during the last trimester of pregnancy and then again during the first 2 months of lactation. The mothers in 1 group drank carrot juice during pregnancy and water during lactation; mothers in a second group drank water during pregnancy and carrot juice during lactation, whereas those in the control group drank water during both pregnancy and lactation. Approximately 4 weeks after the mothers began complementing their infants' diet with cereal and before the infants had ever been fed foods or juices containing the flavor of carrots, the infants were videotaped as they fed, in counterbalanced order, cereal prepared with water during 1 test session and cereal prepared with carrot juice during another. Immediately after each session, the mothers rated their infants' enjoyment of the food on a 9-point scale. RESULTS: The results demonstrated that the infants who had exposure to the flavor of carrots in either amniotic fluid or breast milk behaved differently in response to that flavor in a food base than did nonexposed control infants. Specifically, previously exposed infants exhibited fewer negative facial expressions while feeding the carrot-flavored cereal compared with the plain cereal, whereas control infants whose mothers drank water during pregnancy and lactation exhibited no such difference. Moreover, those infants who were exposed to carrots prenatally were perceived by their mothers as enjoying the carrot-flavored cereal more compared with the plain cereal. Although these same tendencies were observed for the amount of cereal consumed and the length of the feeds, these findings were not statistically significant. CONCLUSIONS: Prenatal and early postnatal exposure to a flavor enhanced the infants' enjoyment of that flavor in solid foods during weaning. These very early flavor experiences may provide the foundation for cultural and ethnic differences in cuisine.

Amniotic Fluid↗
PubMed2000

Parent-progeny recognition as a function of MHC odortype identity.

The several linked polymorphic genes of the MHC, which has been proposed as a prime determinant of sensed genetic individuality within species, is known to operate in mice by olfactory recognition in aspects of reproductive behavior that concern mate selection, thereby favoring outbreeding and heterozygosity, and also concern the maintenance of pregnancy. A single base-change can alter an individual MHC odortype, and the potential range of combinatorial MHC-determined odortypes is clearly vast. Following our findings that newborn mice already express their MHC odortype (which is detectable at 9 days of gestational age), we sought to determine whether MHC is involved in behavioral aspects of early development, such as rearing. In the studies presented herein, we report the ability and proclivity of mothers to recognize and preferentially retrieve syngeneic (genetically identical) pups from other pups differing only for MHC. Reciprocally, we report the ability of pups to recognize their familial environment, regardless of whether they had been nursed by their biological mothers or by foster mothers. Early learning experiences of the MHC environment are apparently a key element in survival, assuring maternal protection and promoting outbreeding.

Animals↗
PubMed2000

Effect of B2m gene disruption on MHC-determined odortypes.

Major histocompatibility complex (MHC) genes confer individual olfactory identity that can be detected with exquisite accuracy by mice. The fact that MHC genes themselves generate the characteristic odortype, rather than dedicated odor-determining genes, was supported in studies of point mutations in H2K and HLA transgenic mice, which evinced distinct odor profiles in olfactory assays. In this article we provide further evidence for a central role of MHC genes themselves in odortype specification by demonstrating that mice that are unable to express their genomic class I MHC genes because they lack beta2-microglobulin are distinguishable by scent from otherwise identical mice which possess an intact B2m gene. This odortype disparity appears at 9-12 days of gestational age, the period in which the MHC is first detectable in fetal cells of normal mice.

Animals↗
PubMed2000

Intake of umami-tasting solutions by mice: a genetic analysis.

In two-bottle preference tests with water and solutions of monosodium glutamate (MSG) and inosine-5'-monophosphate (IMP), mice from the C57BL/6ByJ inbred strain consumed more and had higher preferences for these solutions compared with mice from the 129/J strain. The C57BL/6ByJ mice consumed 300 mmol/L MSG in large amounts, which were comparable to intakes of highly preferred solutions of sweeteners. The strain differences in voluntary consumption of 300 mmol/L MSG depended at least in part on postingestive effects because prior experience with MSG influenced the expression of the strain difference in MSG acceptance. The strain difference in MSG acceptance was in the opposite direction to the strain difference in NaCl acceptance and was not affected by previous consumption of saccharin. Although the C57BL/6ByJ mice had higher avidity for both MSG and sweeteners than did the 129/J mice, there was no correlation between preferences for these solutions in the second hybrid generation (F(2)) derived from these two strains. Thus, the strain differences in MSG acceptance are not related to the strain differences in salty or sweet taste responsiveness and most likely represent specific umami taste responsiveness. High acceptance of MSG solutions by the C57BL/6ByJ mice was inherited as a recessive trait in the F(2) generation. Further genetic linkage analyses using the F(2) hybrids are being conducted to map chromosomal locations of genes determining the strain difference in MSG acceptance.

Animals↗
PubMed1999

Odortypes: their origin and composition.

Odors that distinguish one individual from another member of the species and are determined by polymorphic genes are called odortypes. Odortypes and their considerable societal significance have been studied intimately only in mice and mainly with respect to the genes of the major histocompatibility complex. Further understanding and the matter of human relevance have been hampered by the apparent restriction of odortype expression to urine. The present finding that odorants comprising prerenal odortypes are already present in blood, albeit in masked form, affords the basis of a comprehensive view of odortypes. Accordingly, major histocompatibility complex and other polymorphic genes of antiquity are seen inter alia as agents of normal variation, which entails quantitative variation in output of odorant metabolites. Relatively few such normal variations should suffice for a vast range of compound odors whose specificity is determined by combinative assortment of the same set of individual volatile compounds.

Animals↗
PubMed1999

Experience with a flavor in mother's milk modifies the infant's acceptance of flavored cereal.

The present series of studies aimed to investigate whether experience with a flavor in mothers' milk modifies the infants' acceptance of similarly flavored foods at weaning. First, we established, using methods developed in our laboratory, that the ingestion of carrot juice by lactating women produced a sensory change in their milk approximately 2 to 3 hr after the ingestion of the beverage. Second, we randomly formed two groups of breast-fed infants who had been fed cereal for a few weeks but had only experienced cereal prepared with water. Their mothers were asked to consume one of two types of beverages (i.e., carrot juice, water) during the exposure period. Each mother was observed feeding her infant cereal during four test sessions. The first two sessions occurred during the 2 days before the exposure period; in counterbalanced order, infants were fed cereal prepared with water on 1 testing day and cereal prepared with carrot juice on the other. These two test sessions were then repeated following the exposure period. The results demonstrated that the infants who had exposure to the flavor of carrots in their mothers' milk during the exposure period consumed less of the carrot-flavored cereal and spent less time feeding when compared to the control infants whose mothers consumed the water. This may be a form of sensory-specific satiety such that the infants become less responsive to a flavor that they have been extensively exposed to in the very recent past.

Adult↗
PubMed1998

Development and genetics of glutamate taste preference.

The sodium salt of glutamic acid, monosodium glutamate (MSG), and certain other amino acids and ribonucleotides impart a unique taste sensation often called 'umami.' We have been studying preference for umami substances in two systems: inbred mice and human infants. In 48-hr tests, C57BL/6J (C57) mice exhibit a lower preference threshold for MSG than do 129/J mice. Moreover, C57 mice show a greater preference across a wide range of concentrations and, at high (e.g., 300-600 mM) concentrations, consume greater amounts of MSG. To examine whether the strain difference in MSG preference might be related to a similar strain difference in preference for sucrose and other sweeteners, as might be suggested from studies with rats, preferences for MSG and sucrose in the second (F2) generation were examined. Preferences for sucrose and for MSG were not positively correlated in the F2 indicating that these strain differences depend on different genes. For human adults, unlike mice, the taste of aqueous MSG is not palatable. Our studies of human infants also indicate that MSG alone is not preferred to plain water, but, when it is added to soup, the soup plus MSG is preferred to soup alone. Ongoing studies are designed to determine whether simple mixtures of MSG with other tastants, in particular NaCl, are preferred to water alone, NaCl alone, and MSG alone.

Adult↗
PubMed1998

Consumption of electrolytes and quinine by mouse strains with different blood pressures.

Daily fluid intakes were measured using two-bottle tests in female mice of inbred strains with high (BPH/2), normal (BPN/3) or low (BPL/1) blood pressure. The mice were offered a choice between water and different concentrations of NaCl (37.5-600 mM), KCl (1-400 mM), CaCl2 (1-100 mM) and quinine hydrochloride (0.003-1.0 mM). Compared with the normotensive strain, the hypertensive mice had higher water and total fluid intakes, and lower intakes of NaCl, KCl (only 200 mM) and quinine; the hypotensive mice had higher intakes of KCl (only 10-50 mM) and lower intakes of CaCl2 and quinine. These data suggest that fluid and salt intake are not linearly related to blood pressure, but are independently determined in these strains. Certain concentrations of the salts were preferred relative to water, which depended on mouse genotype: the BPN/3 and BPL/1 mice strongly preferred 37.5-150 mM NaCl, the BPL/1 mice preferred 10-100 mM KCl, and the BPN/3 mice preferred 1-10 mM CaCl2.

Animals↗