Glycoconjugate in rat taste buds.

The taste buds of the fungiform papillae, circumvallate papilla, foliate papillae, soft palate and epiglottis of the rat oral cavity were examined by lectin histochemistry to elucidate the relationships between expression of glycoconjugates and innervation. Seven out of 21 lectins showed moderate to intense staining in at least more than one taste bud. They were succinylated wheat germ agglutinin (s-WGA). Dolichos biflorus agglutinin (DBA), Bandeiraea simplicifolia lectin-I (BSL-I), Ricinus communis agglutinin-I (RCA-I), peanut agglutinin (PNA), Ulex europaeus agglutinin-I (UEA-I) and Phaseolus vulgaris agglutinin-L (PHA-L). UEA-I and BSL-I showed moderate to intense staining in all of the taste buds examined. They strongly stained the taste buds of the epiglottis, which are innervated by the cranial nerve X. UEA-I intensely stained the taste buds of the fungiform papillae and soft palate, both of which are innervated by the cranial nerve VII. The taste buds of circumvallate papilla and foliate papillae were innervated by the cranial nerve IX and strongly stained by BSL-I. Thus, UEA-I and BSL-I binding glycoconjugates, probably alpha-linked fucose and alpha-D-galactose, respectively, might be specific for taste buds. Although the expression of these glycoconjugates would be related to the innervation of the cranial nerve X, the differential expression of alpha-linked fucose and alpha-D-galactose might be related to the innervation of the cranial nerve VII and IX, respectively.     

The distribution of taste buds in Garra rufa

The distribution and relative frequency of external taste buds (TB) of Garra rufa were studied. TB of Garra rufa were observed on different body location (lips, lateral and ventral areas, forehead, operculum and dorsal-pelvic-pectoral-anal fins). TB are at the highest frequency in lips, forehead, pectoral and anal fins. These structures are moderate as a number in operculum, La2 (between pelvic and anal fins) areas, and then decreased a few in other areas.     

The lingual taste buds of Gallus domesticus L

The so‐called “ taste buds “ of the chicken were examined. It was found that they had one or more pores and were composed of a single cell type. There was a nerve plexus at the base of the bud giving rise to fibres which entered the bud. The cells showed acetyl cholinesterase activity and were found to degenerate following denervation. Thus they closely parallel, in both structure and neural dependency, the taste buds in other vertebrates and it is concluded that they probably are true taste buds.     

Gustducin is expressed in the taste buds of the chicken

We investigated the expression of gustducin in chicken taste buds using molecular biological, biochemical and immunohistochemical techniques. Expression of a gustducin‐like sequence was detected by RT‐PCR in the tissues containing taste buds, and corresponded to the predicted gustducin gene in the chicken. Expression of this sequence was not detected in the brain, heart, liver, pancreas, intestine, kidney and testis of the chicken. The expressed sequence had a high specificity for oral tissues that contained taste buds. These results suggest that the detected sequence was the chicken gustducin gene. Next, we generated a polyclonal antiserum against the chicken gustducin protein to observe its localization in the oral tissues. The results revealed that the chicken gustducin was specifically expressed in the taste buds. It is suggested that the chicken has a gustatory system mediated by gustducin, and chicken gustducin is a reliable marker for taste buds or taste cells. This is the first molecular biological, biochemical and immunohistochemical demonstration of the presence of gustducin in the chicken.     

The number of taste buds is related to bitter taste sensitivity in layer and broiler chickens

The relationship between taste sensitivity and the number of taste buds using a bitter tastant, quinine hydrochloride, was investigated in White Leghorn, Rhode Island Red, and broiler chickens. The White Leghorn and Rhode Island Red strains were able to perceive 2.0 mmol/L quinine hydrochloride, but the taste sensitivity of Rhode Island Red chickens was higher than that of White Leghorn chickens. Broiler chickens perceived 0.5 mmol/L quinine hydrochloride. The number of taste buds in the White Leghorn strain was the lowest, then the Rhode Island Red strain, with the number of taste buds highest in the broiler chickens. The number of taste buds was well correlated with bitter taste sensitivity. Therefore, we suggest that the number of taste buds is a vital factor in the perception of bitter taste and may be useful in selecting appropriate feeds for chickens.     

Temporal lectin histochemical characterization of porcine small intestine.

A variety of biotinylated lectins was applied to formalin-fixed intestinal sections from isolator-reared pigs ranging in age from newborn through 12 weeks. Lectin binding to brush borders of villus enterocytes, crypt enterocytes, and dome epithelium, and lectin reactivity within goblet cells and Brunner's glands was semiquantified by microscopy and was used to estimate temporal changes in complex carbohydrates of enteric epithelium. Although variability in binding scores often was observed among pigs of the same age, several general patterns of lectin binding were detected. Dolichos biflorus and Ulex europaeus lectins had increasing binding to brush border membranes as pigs aged. The Dolichos biflorus, however, had decreased binding at the 12-week time point. Neuraminidase-treated Arachis hypogaea and Triticum vulgaris were associated with high mean binding scores at all time points. Canavalia ensiformis bound, with high mean score at all time points, to villus but not to crypt enterocytes. Arachis hypogaea was associated with variable but often high binding scores, regardless of pig age. Succinylated wheat germ agglutinin bound more to crypt than to villus enterocytes. Goblet cells were generally less reactive than were corresponding villi and crypts. Dome epithelium reactivity varied with the lectin used, whereas Brunner's glands reacted with all lectins tested. We conclude that age and regional variations in lectin binding may reflect differences in intestinal function and differentiation. Because complex carbohydrates may act as cell surface receptors for a variety of enteric pathogens, our results indicate that these differences may be partially responsible for age and anatomic differences in susceptibility or resistance to enteric disease.     

Structure of bovine fungiform taste buds and their immunoreactivity for gustducin

The taste buds of bovine fungiform papillae were studied by light and electron microscopy using both histological and immunohistochemical methods. The taste buds existed in the epithelium of the apical region of the papillae. By electron microscopy, two types of taste cells, namely type I and type II cells, could be classified according to the presence of dense-cored vesicles, the cytoplasmic density and the cell shape. Type I cells were thin, had an electron-dense cytoplasm containing dense-cored vesicles, and possessed long thick apical processes in the taste pore. Type II cells were thick, had an electron-lucent cytoplasm containing many electron-lucent vesicles, rather than dense-cored vesicles, and possessed microvilli in the taste pore. Immunohistochemical staining with an antiserum against gustducin was investigated by both light and electron microscopy using the avidin-biotin complex (ABC) method. Some, but not all, of the type II cells exhibited gustducin immunoreactivity, whereas none of the type I cells showed any immunoreactivity.     

The distribution of external taste buds in flower fish (Pseudophoxinus antalyae)

Purpose of this study was to determine the distribution of external taste buds of flower fish (Pseudophoxinus antalyae) on different body locations (lip, lateral, ventral and dorsal areas, dorsal-pelvic-pectoral-anal fins). In this species, it was found that the density of taste buds was greater on lip epithelium than that of lateral (between pectoral-anal, anal-caudal fins), ventral (between pelvic and anal fins) and dorsal (close to the head) locations. It was observed that the shape of taste bud changed depending upon the epithelium thickness and it was found that some of these structures protruded towards to the exterior of epithelium.     

哺乳动物性别控制研究进展

在自然条件下.哺乳动物几乎均等的性别比例,使哺乳动物(包括人类在内)可以无间断地衍生后代.从而达到自然的生态平衡.然而,人类在衍生自己的后代和在农业生产过程中.为了达到某种需求而对性别控制进行了不懈的努力.     

Distribution of taste buds in layer‐type chickens: Scanning electron microscopic observations

The distribution of taste buds of layer‐type chickens, from day 1 (H1) to day 140 (H140) post‐hatching, were investigated histologically and with a scanning electron microscope. Two types of openings were observed on the oral epithelium: large openings that were greater than 10 μm in width, and had an ellipsoid or spindle shape; and small openings that were less than 7 μm in width, and had a circular or polygon shape. It was defined that the former represent the openings of the salivary glands, and the latter are those of the taste buds. The number of taste buds remained constant from H1 to H140. Therefore, no significant change was observed between these two time points. To investigate the distribution of the taste buds in the whole oral cavity, a distribution map was created.     

A lectin histochemical study of the zygomatic salivary gland of adult dogs

Seven lectins (PNA, DBA, SBA, UEA I, LTA, WGA and ConA), conjugated with horseradish peroxidase, were used to characterize the glycosidic residues in the zygomatic gland of adult dogs. In some cases (PNA and DBA), lectin staining was preceded by neuraminidase digestion. The acinar and tubular cells produced glycoconjugates with different sugar residues, presenting binding sites for all of the lectins used. The apical surfaces of the cells lining the intra- and interlobular ducts were also stained by all the lectins. In contrast, the demilunar cells only reacted with the Neu-PNA sequence and Con A. Abbreviations: Neu, neuraminidase; see also Table I     

Isolation of chicken taste buds for real‐time Ca2+ imaging

We isolated chicken taste buds and used a real‐time Ca²⁺ imaging technique to investigate the functions of the taste cells. With RT‐PCR, we found that isolated chicken taste bud‐like cell subsets express chicken gustducin messenger RNA. Immunocytochemical techniques revealed that the cell subsets were also immunopositive for chicken gustducin. These results provided strong evidence that the isolated cell subsets contain chicken taste buds. The isolated cell subsets were spindle‐shaped and approximately 61–75 μm wide and 88–98 μm long, and these characteristics are similar to those of sectional chicken taste buds. Using Ca²⁺ imaging, we observed the buds' response to 2 mmol/L quinine hydrochloride (a bitter substance) and their response to a mixture of 25 mmol/L L‐glutamic acid monopotassium salt monohydrate and 1 mmol/L inosine 5′‐monophosphate disodium salt, umami substances. The present study is the first morphological demonstration of isolated chicken taste buds, and our results indicate that the isolated taste buds were intact and functional approaches for examining the taste senses of the chicken using Ca²⁺ imaging can be informative.     

A lectin histochemical study of the thoracic respiratory air sacs of the fowl

The lectin-binding characteristics of the epithelial lining of the thoracic air sacs of the chicken were determined. Con A, LCA and PSA bound to the apical membrane as well as to the cytoplasm distal to the nucleus of the surface epithelium, indicated the presence of a-linked mannose as well as N-acetylchitobiose-linked alpha-fucose residues in the glycoproteins. GSL I bound to the apical membrane and cytoplasm distal to the nucleus, but not to the cilia of the epithelium, where-as MPL, DBA and RCA120 bound to the apical membrane, cilia and cytoplasm, indicated the presence of a-linked N-acetylgalactosamine residues. However, neither SJA or SBA showed any binding, indicating the absence of beta anomers of galactosyl (beta1.3)N-acetylgalactosamine and beta-linked N-acetylgalactosamine residues. UEA I bound to the apical membrane and cilia, as well as to the cytoplasm of a few cells, indicated the presence of alpha-linked fucose residues. PNA bound to the apical membrane of some, but not all, surface epithelium cells, indicated the presence of galactosyl (beta1.3)N-acetylgalactosamine residues. WGA bound to the apical membrane and cilia, as well as to the cytoplasm of a few cells, indicated the presence of neuraminic acid residues.     

Comparative studies on the histochemical properties of M. iliotibialis lateralis from Kumamoto Cochin crossbred roaster and broiler chickens

1. Histochemical properties of M. iliotibialis lateralis were compared between Kumamoto Cochin (a Japanese native breed) crossbred roasters (KC roasters, 112 d of age) and normal broilers (56 d of age).

2. Myofibres were divided into Types II‐R, II‐I and II‐W showing high, moderate and low reduced nicotinamide adenine dinucleotide dehydrogenase (NADH‐DH) activities, respectively.

3. Subsarcolemmal formazan granules indicating very strong NADH‐DH activity in Type II‐R fibres were observed only in KC roasters. In both sexes the percentage of Type II‐R fibres present was greater in KC roasters than in broilers.

4. These results indicated marked differences in histochemical properties and meat quality between KC roasters and broilers.     

Histological and histochemical studies on the chicken lingual glands

1. Morphological and histochemical observations were done on the chicken anterior and posterior lingual glands. Histology, ultrastructure and glycoconjugate histochemistry were investigated by means of light and electron microscopy using staining specific for complex carbohydrates. 2. In the anterior lingual glands there are lateral and medial zones showing different morphological and tinctorial features. The secretory cells are typical mucous cells. 3. Histochemical reactions revealed the presence of acidic glycoconjugates with terminal sialic acid residues, and glycoconjugates vicinal diol and sulphate groupings in the secretory granules. 4. It is suggested that the main functions of lingual glands are the lubrication of boli and protection from micro-organisms.     

A lectin histochemical study on the testis of the babirusa, Babyroussa babyrussa (Suidae)

The distribution of lectin bindings in the testis of babirusa, Babyrousa babyrussa (Suidae) was studied histochemically using 10 biotinylated lectins, Peanut agglutinin (PNA), Ricinus communis agglutinin (RCA I), Dolichos biflorus agglutinin (DBA), Vicia villosa agglutinin (VVA), Soybean agglutinin (SBA), Wheat germ agglutinin (WGA), Lens culinaris agglutinin (LCA), Pisum sativum agglutinin (PSA), Concanavalin A(Con A) and Ulex europaeus agglutinin (UEA I). Nine of 10 lectins showed a variety of staining patterns in the seminiferous epithelium and interstitial cells. The acrosome of Golgi-, cap- and acrosome-phase spermatids displayed various PNA, RCA I, VVA, SBA and WGA bindings, indicating the presence of glycoconjugates with D-galactose, N-acetyl-D-galactosamine and N-acetyl-D-glucosamine sugar residues respectively. No affinity was detected in the acrosome of late spermatids. LCA, PSA and Con A which have affinity for D-mannose and D-glucose sugar residues were positive in the cytoplasm of spermatids and spermatocytes. DBA was positive only in spermatogonia. In addition to DBA, positive binding in spermatogonia was found for VVA, WGA and Con A, suggesting the distribution of glycoconjugates with N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, D-mannose and D-glucose sugar residues. Sertoli cells were stained intensely with RCA I, WGA and Con A. In Leydig cells, RCA I and Con A were strongly positive, while WGA, LCA and PSA reactions were weak to moderate. The present findings showed that the distribution pattern of lectin binding in the testis of babirusa is somewhat different from that of pig or other mammals reported previously.