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 occurrence of taste buds in adults of the terrestrial ceacilian Boulengerula boulengeri Tornier, 1898 (Lissamphibia: Gymnophiona: Herpelidae)

Two generations of gustatory organs occur during amphibian ontogeny in frogs and salamanders (Anura and Caudata), and are classified as taste buds or taste discs. Taste buds are present in larval forms, whereas taste discs are typical for adults. The little research done on Gymnophiona suggests that only taste buds are present in aquatic forms (larvae and adults), and adults of the only terrestrial species studied had taste buds. Here we investigate the nature of gustatory organs in a terrestrial caecilian, Boulengerula boulengeri (Herpelidae), from Tanzania using standard light and scanning electron microscopy. We found only taste bud type organs to be present in B. boulengeri. These occur mainly in the mucosa of the front part of the oral cavity, usually near the teeth. Our results suggest that B. boulengeri possesses only one type of gustatory organ during its ontogeny.     

Investigations on the light and scanning electron microscopic structure of the lingual papillae in the angora goat (Capra hircus): II. Mechanical papillae

This study was conducted to examine the light microscopy (LM) and scanning electron microscopic (SEM) structures of mechanical papillae on the tongue in the Angora goat (Capra hircus). As study materials, the tongues of four adult female Angora goats were used. The samples were collected from the dorsal surfaces of the apex, body, root and torus of the tongue and the ventral surfaces of the lingual apex for light and scanning electron microscopic examinations. Three types of mechanical papillae were seen in Angora goat tongue: papilla filiformes, papilla lentiformes and papilla conicae.The filiform papillae were detected in the dorsal surface of the tongue from lingual apex to lingual torus, and in the ventro-lateral of the lingual apex and on both sides of the lingual torus. The morphological differences were observed in filiform papillae according to their location in the tongue. The lenticular papillae settled on the centre of the lingual torus. Two types of these papillae, irregular-round and pyramid-shaped were identified. The conical papillae were scattered all over the lingual torus, except for the central part and were also seen on the root of the tongue. In the light microscopic examination, it was found that mechanical papillae had a stratified squamous epithelium and a varying degree of keratin layer on epithelial surfaces. In this study, by examining the light and scanning electron microscopic structure of the mechanical papillae in the Angora goat tongue, their similarities and differences with other domestic and wild ruminant species were determined.     

Effects of muscle type on beef taste‐traits assessed by an electric sensing system

To assess the role of muscle fiber type in beef taste‐traits, we analyzed cooked meats from bovine masseter, diaphragm, psoas major, longissimus thoracis, and semitendinosus muscles with an electric taste sensing system (INSENT SA402B). The system is composed of five taste sensors of polymer membranes fixing different lipids. The sensors, CT0, CA0, AAE, C00 and AE1 are designed to respond to the individual tastes of salty, sour, umami, bitter and astringent, respectively. The system found significant differences in the converted outputs of CA0 (cvCA0), C00 (cvC00) and AE1 (cvAE1) among the bovine muscles. The slow‐type muscles (masseter and diaphragm) showed lower cvCA0, higher cvC00, and higher cvAE1 than did the fast‐type muscles (psoas major, longissimus thoracis, and semitendinosus). Lactic acid content was different among muscle types and was highly related to the cvCA0 output and pH. carbonyl compounds and free fatty acids were higher in the slow‐type muscles. Free fatty acids were major components causing the difference in the C00 output among the muscle types. Iron content was also different among the muscle types and related to the cvC00 and cvAE1 outputs. These results suggested that the muscle fiber type affects the beef taste characteristics.     

Correlation between skeletal muscle fiber type and responses of a taste sensing system in various beef samples

The difference of muscle fiber type composition affects several parameters related to meat quality; however, the relationship between muscle fiber types and meat taste is unclear. To elucidate this relationship, we determined the taste of various beef samples using a taste sensor (INSENT SA402B) and analyzed its correlation with different muscle fiber type composition. We used 22 kinds of beef samples and measured nine tastes, including the relative and change of membrane potential caused by adsorption (CPA) values, using six sensors (GL1, CT0, CA0, AAE, C00, and AE1). The taste sensor analysis indicated positive value outputs for the relative C00, AAE, and GL1 values as well as for the CPA value of AAE, which corresponded to bitterness, umami, sweetness, and richness, respectively. We found significant positive correlations of the myosin heavy chain 1 (MyHC1) composition with umami taste, and with richness. This result suggests that high levels of slow MyHC1 can induce strong umami taste and richness in beef. We expect that our results will contribute to the elucidation of the relationship between muscle fiber types and meat palatability.     

Hypophagic and dipsogenic effect of the 5‐HT1A receptor agonist 8‐OH‐DPAT in broiler chickens

The effects of the 5‐HT_1A receptor agonist 8‐OH‐DPAT on food and water intake in male broiler chickens were investigated. The injection of 25 or 50 μg/kg of 8‐OH‐DPAT 15 min before refeeding in fasted animals produced a decrease in food intake. No effect was observed in drinking. The injection of 25 or 50 μg/kg of the 8‐OH‐DPAT 60 min after the start of refeeding did not produce any significant modification in food intake. No effect on drinking was recorded. The agonist 8‐OH‐DPAT injected 15 min before water presentation in water‐deprived chickens, produced an increased drinking 60 min after the presentation of water. No effect on food intake was observed. The results show that the effect on food intake of the agonist 8‐OH‐DPAT in fasted–refed broiler chickens was similar to those observed in mammals and layer‐strain chickens. However, the agonist did not alter significantly the food intake when the broilers were fed 60 min before the injection. These results are contrary to the observed effects in mammals and in layer‐strain chickens. Probably, the selection for rapid growth rate in broilers causes modifications in the feeding control pattern. The comparison between broilers and layers strain may be a useful tool to elucidate the complex mechanisms involved in food and water intake regulation in chickens.     

Proteomic analysis of the hypothalamus of broiler‐type Taiwan country chickens in response to acute heat stress

The hypothalamus is a critical center for regulating heat retention or dissipation. This study investigated global protein changes in the hypothalamus of broiler‐type Taiwan country chickens (TCCs) after acute heat stress. Twelve TCC hens aged 30 weeks were allocated to groups subjected to acute heat stress at 38°C for 2 hr without recovery, with 2 hr of recovery, and with 6 hr of recovery; a control group was maintained at 25°C. Hypothalami were collected for protein expression analysis at the end of each time point. The results showed 114 protein spots differentially expressed after acute heat stress. Most of the differentially expressed proteins were involved in cellular processes, metabolism, transport, and cellular component organization. Functional annotation analysis suggested that these proteins were related to cellular defensive responses against heat and oxidative stress, detoxification and toxin export/delivery, cytoskeleton integrity, oxygen transport, and neural development. The results of this study suggest that acute heat stress damages the hypothalamus of broiler‐type TCCs through oxidative stress and provokes a series of responses to stabilize protein structures, degrade misfolded proteins, and remodel cytoskeletons for attenuating the detrimental effects by acute heat stress.     

Effect of the strain combination of the donor and recipient on the production efficiency of W‐bearing sperm in mixed‐sex germline chimeric chickens

Effect of the strain combination of the donor and recipient on production efficiency of W‐bearing sperm in mixed‐sex chimeric testes was analyzed. The combinations of the donors and recipients were White Leghorn (WL) and Rhode Island Red (RIR), and vice versa. Generated mixed‐sex chimeras that had the male phenotype at sexual maturity were classified into four groups: (1) a female WL donor and a male RIR recipient; (2) a male WL donor and a female RIR recipient; (3) a female RIR donor and a male WL recipient; (4) a male RIR donor and a female WL recipient. The mean number of W‐bearing sperm detected by in situ hybridization among 10 000 sperm observed were 147, 165, 30 and 45 in groups 1, 2, 3 and 4, respectively. The numbers in groups 1 and 2 were both significantly higher than those of groups 3 and 4 (P < 0.05). The combination of a WL donor and a RIR recipient produced W‐bearing sperm more efficiently than the reverse combination.     

Effects of supplementation with β‐carotene on the growth performance and intestinal mucosal barriers in layer‐type cockerels

β‐carotene is a robust modulator of mucosal barriers, and it can amplify the immunoglobulin A (IgA) response via the retinoic acid (RA)–mediated pathway. We investigated the influence of β‐carotene on intestinal barriers in layer‐type cockerels. In this study, β‐carotene has a positive influence on growth performance and intestinal morphology. β‐carotene remarkably enhanced serum secretory immunoglobulin A (sIgA) levels, jejunal mucosal sIgA, and IgA concentrations. β‐Carotene significantly enhanced mRNA expression levels of IgA, CC chemokine receptor‐9 (CCR9), polymeric immunoglobulin receptor (pIgR), and retinoic acid receptor α (RARα) in the ileal tissues and pIgR in the jejunal tissues. β‐Carotene improves mRNA expression of intestinal barrier‐related proteins including: mucin‐2 (MUC‐2), zonula occludens‐2 (ZO‐2), occludins (OCLN), and zonula occludens‐1 (ZO‐1) in the ileal tissues. Moreover, β‐carotene decreased the levels of Escherichia coli and elevates the levels of Lactobacillus. The results indicate that β‐carotene can promote growth performance and contribute to the gradual development of intestinal barriers in Hyline Brown chicks. This study enriches our knowledge about the effects of β‐carotene on intestinal barrier and highlights a theoretical basis of β‐carotene application in the poultry industry.     

Simple method for isolation of glyceraldehyde 3‐phosphate dehydrogenase and the improvement of myofibril gel properties

Porcine glycoliytic enzyme, glyceraldehyde 3‐phosphate dehydrogenase (G3PD) was prepared effectively by a combination of ethylene diamine tetra‐acetate (EDTA) pretreatment and affinity purification. After salting out of porcine sarcoplasmic proteins (SP) with ammonium sulfate at 75% saturation, the obtained supernatant (SP‐f3) was treated with EDTA, leaving G3PD in the supernatant (G3PD‐E) and most other SPs in the precipitate. At that time, the separation of G3PD‐E required more than 20 mmol/L EDTA. G3PD‐E was then subjected to affinity purification by batchwise method using blue‐sepharose CL‐6B, and purified G3PD (G3PD‐AP) was obtained using 2 mol/L potassium chloride (KCl) as an eluent. Texture analysis showed that the hardness, adhesiveness and gumminess of the myofibril gel at 0.2‐mol/L NaCl increased with the addition of G3PD‐AP. Scanning electron microscopy revealed that the G3PD‐AP reinforced the gel network of the myofibril. However, scanning electron micrograph analysis showed that the network‐structure of the gel by the addition of G3PD‐AP developed in a different manner from that by adding 0.6 mol/L NaCl. These results showed that glycolytic enzyme, G3PD, contributes to the improvement of the rheological properties of meat products.     

Gender‐specific effects of a phytogenic feed additive on performance,intestinal physiology and morphology in broiler chickens

To date, most studies published were carried out on broilers of the same sex, and possible gender‐specific effects of phytogenic substances have not been investigated so far. A 3 × 2 factorial study was performed to examine gender‐specific effects of a PFA at two dietary levels (150, 1500 ppm) on growth performance, carcass traits and gastrointestinal attributes in broiler chickens versus an untreated control group. The addition of 150 ppm of the PFA led to a downregulation of trypsinogen mRNA in pancreas compared with the control group (p < 0.05). The number of goblet cells decreased in jejunum compared with the unsupplemented group, whereby this effect was more pronounced in male birds (p < 0.05). Furthermore, higher methylamine contents compared with the control group were measured (p < 0.01). In proximal ileum, female birds, supplemented with 150 ppm PFA, had lower crypt depths than their litters in the 1500 ppm treatment (p < 0.05). In distal ileum, villus height:crypt depth ratio was higher in birds fed the PFA at 150 ppm than in the control group (p < 0.05). The 1500 ppm dosage of the PFA increased jejunal histamine concentration compared with the negative control group (p < 0.05). Jejunal histamine concentration was also affected by the interaction PFA × sex (p < 0.05). Regardless of inclusion level, total amount of biogenic amines and other microbial metabolites in digesta samples was not affected by the PFA. These results demonstrate variable, partially gender‐specific effects of the tested PFA. Although the supplementation of 150 ppm showed little effect on mRNA expression level of selected marker genes for nutrient digestion, beneficial effects on gut morphology were observed. The 10‐fold higher dosage of the PFA did not adversely affect growth performance as well as most investigated parameters compared with the control group.     

Expression levels of taste‐related genes in palate and tongue tip,and involvement of transient receptor potential subfamily M member 5 (TRPM5) in taste sense in chickens

The elucidation of the mechanisms underlying the taste sense of chickens will contribute to improvements in poultry feeding, because the molecular mechanism of chickens’ taste sense defines the feeding behavior of chickens. Here we focused on the gene expressions in two different oral tissues of chickens – the palate, which contains many taste buds, and the tongue tip, which contains few taste buds. Using the quantitative real‐time polymerase chain reaction method, we found that the molecular markers for taste buds of chickens, that is α‐gustducin and vimentin, were expressed significantly highly in the palate compared to the tongue tip. Our analyses also revealed that transient receptor potential subfamily M member 5 (TRPM5), a cation channel involved in taste transduction in mammals, was also highly expressed in the palate compared to the tongue tip. Our findings demonstrated that the expression patterns of these genes were significantly correlated. We showed that the aversion to bitter solution was alleviated by a TRPM5 inhibitor in behavior of chickens. Taken together, our findings enabled us to develop a simple method for screening taste‐related genes in chickens. The use of this method demonstrated that TRPM5 was involved in chickens’ taste transduction, and that a TRPM5 inhibitor can alleviate chickens’ bitter taste perception of feed ingredients.     

Minimally‐invasive plate osteosynthesis of a Salter‐Harris type 2 fracture of the proximal phalanx in a filly

A 7‐month‐old Warmblood filly was referred to the equine hospital because of a Salter‐Harris type 2 fracture of the proximal physis of the right hind P1. On admission, the filly had acute grade 3/5 lameness at the walk and diffuse swelling in the area of the right hind proximal phalanx. Radiographs were taken to assess the fracture and plan treatment. Surgical treatment using two 4.5 mm narrow locking compression plates (PIP‐LCPs) resulted in fracture stabilisation and rapid healing. This case report suggests that internal fixation using PIP‐LCPs is useful for the treatment of Salter‐Harris type 2 fractures of the proximal physis of P1 in large foals.     

Influence of feed type and its effect on repressing wool‐biting behavior in housed sheep

Sheep sometimes develop an abnormal behavior termed as wool‐biting when kept in an indoor system; however, little is known about this behavior. As the provided feed type may affect the foraging behavior and repress abnormal behavior in animals, we tested the effect of feed type on repressing wool‐biting behavior in this study. We used hay prepared in three forms, that is hay bales, rolls and cubes. The wool‐biting frequency associated with hay bales was significantly higher than that associated with rolls (P < 0.05) and cubes (P < 0.05); however, there was no significant difference between rolls and cubes. For hay rolls, wool‐biting significantly decreased after feeding (P < 0.05), suggesting that rolls may provide sheep with appropriate oral stimulation; thus, decreasing the post‐feeding oral abnormal behavior. An individual difference of wool‐biting behavior between sheep was also detected, and an unexpected bed‐eating behavior was found in the hay cube treatment. We suggest that sheep performing movements that are similar to their natural foraging behavior while grazing would repress wool‐biting behavior, which happened in hay roll and hay cube treatments. Considering sanitation and animal welfare, providing sheep with hay rolls may provide an easier method to control wool‐biting behavior in housed sheep.     

Fast‐to‐slow shift of muscle fiber‐type composition by dietary apple polyphenols in rats: Impact of the low‐dose supplementation

Our previous studies demonstrated that an 8‐week intake of 5% (w/w) apple polyphenol (APP) in the diet improves muscle endurance of young‐adult rats. In order to identify a lower limit of the dietary contribution of APP to the effect, the experiments were designed for lower‐dose supplementation (8‐week feeding of 0.5% APP in AIN‐93G diet) to 12‐week‐old male Sprague‐Dawley rats. Results clearly showed that the 0.5% APP diet significantly up‐regulates slower myosin‐heavy‐chain (MyHC) isoform ratios (IIx and IIa relative to total MyHC) and myoglobin expression in lower hind‐limb muscles examined (P < 0.05). There was a trend to increased fatigue resistance detected from measurements of relative isometric plantar‐flexion force torque generated by a stimulus train delivered to the tibial nerve (F(98, 1372) = 1.246, P = 0.0574). Importantly, there was no significant difference in the animal body‐phenotypes or locomotor activity shown as total moving distance in light and dark periods. Therefore, the present study encourages the notion that even low APP‐intake may increase the proportions of fatigue‐resistant myofibers, and has promise as a strategy for modifying performance in human sports and improving function in age‐related muscle atrophy.     

Distribution of insulin receptor and insulin‐like growth factor‐1 receptor in the digital laminae of mixed‐breed ponies: An immunohistochemical study

Reasons for performing study: Hyperinsulinaemia has been implicated in the pathogenesis of laminitis; however, laminar cell types responding to insulin remain poorly characterised. Objectives: To identify laminar cell types expressing insulin receptor (IRc) and/or insulin‐like growth factor‐1 receptor (IGF‐1R); and to evaluate the effect of dietary nonstructural carbohydrate (NSC) on their expression. Methods: Mixed‐breed ponies (n = 22) received a conditioning hay chop diet (NSC ～6%); following acclimation, ponies were stratified into lean (n = 11, body condition score [BCS]≤4) or obese (n = 11, BCS ≥7) groups and each group further stratified to remain on the low NSC diet (n = 5 each for obese and lean) or receive a high NSC diet (total diet ～42% NSC; n = 6 each for obese and lean) for 7 days. Laminar samples were collected at the end of the feeding protocol and stained immunohistochemically for IRc and IGF‐1R. The number of IRc(+) cells was quantified; distribution of IGF‐1R was qualitatively described. Laminar IRc content was assessed via immunoblotting. Results: The number of IRc(+) cells was greater in the laminae of high NSC ponies than low NSC ponies (P = 0.001); there was a positive correlation between the change in serum insulin concentration and number of IRc(+) cells (r²= 0.74; P<0.0001). No epithelial IRc(+) cells were observed; IRc(+) cells were absent from the deep dermis. Analysis of serial sections identified IRc(+) cells as endothelial cells. The distribution of IGF‐1R was more extensive than that of IRc, with signal in vascular elements, epithelial cells and fibroblasts. Conclusions: Increased dietary NSC results in increased laminar endothelial IRc expression. Laminar keratinocytes do not express IRc, suggesting that insulin signalling in laminar epithelial cells must be mediated through other receptors (such as IGF‐1R). Potential relevance: Manipulation of signalling downstream of IRc and IGF‐1R may aid in treatment and prevention of laminitis associated with hyperinsulinaemia.