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.     

Lineage‐specific evolution of bitter taste receptor genes in the giant and red pandas implies dietary adaptation

Taste 2 receptors (TAS2R) mediate bitterness perception in mammals, thus are called bitter taste receptors. It is believed that these genes evolved in response to species‐specific diets. The giant panda (Ailuropoda melanoleuca) and red panda (Ailurus fulgens styani) in the order Carnivora are specialized herbivores with an almost exclusive bamboo diet (>90% bamboo). Because bamboo is full of bitter tasting compounds, we hypothesized that adaptive evolution has occurred at TAS2R genes in giant and red pandas throughout the course of their dietary shift. Here, we characterized 195 TAS2R genes in 9 Carnivora species and examined selective pressures on these genes. We found that both pandas harbor more putative functional TAS2R genes than other carnivores, and pseudogenized TAS2R genes in the giant panda are different from the red panda. The purifying selection on TAS2R1, TAS2R9 and TAS2R38 in the giant panda, and TAS2R62 in the red panda, has been strengthened throughout the course of adaptation to bamboo diet, while selective constraint on TAS2R4 and TAS2R38 in the red panda is relaxed. Remarkably, a few positively selected sites on TAS2R42 have been specifically detected in the giant panda. These results suggest an adaptive response in both pandas to a dietary shift from carnivory to herbivory, and TAS2R genes evolved independently in the 2 pandas. Our findings provide new insight into the molecular basis of mammalian sensory evolution and the process of adaptation to new ecological niches.     

Molecular evolution of Toll-like receptors in rodents

Toll-like receptors (TLRs), the key sensor molecules in vertebrates, trigger the innate immunity and prime the adaptive immune system. The TLR family of rodents, the largest order of mammals, typically contains 13 TLR genes. However, a clear picture of the evolution of the rodent TLR family has not yet emerged and the TLR evolutionary patterns are unclear in rodent clades. Here, we analyzed the natural variation and the evolutionary processes acting on the TLR family in rodents at both the interspecific and population levels. Our results showed that rodent TLRs were dominated by purifying selection, but a series of positively selected sites (PSSs) primarily located in the ligand-binding domain was also identified. The numbers of PSSs differed among TLRs, and nonviral-sensing TLRs had more PSSs than those in viral-sensing TLRs. Gene-conversion events were found between TLR1 and TLR6 in most rodent species. Population genetic analyses showed that TLR2, TLR8, and TLR12 were under positive selection in Rattus norvegicus and R. tanezumi, whereas positive selection also acted on TLR5 and TLR9 in the former species, as well as TLR1 and TLR7 in the latter species. Moreover, we found that the proportion of polymorphisms with potentially functional change was much lower in viral-sensing TLRs than in nonviral-sensing TLRs in both of these rat species. Our findings revealed the first thorough insight into the evolution of the rodent TLR genetic variability and provided important novel insights into the evolutionary history of TLRs over long and short timescales.     

Patterns and causes of geographic variation in bat echolocation pulses

Evolutionary biologists have a long‐standing interest in how acoustic signals in animals vary geographically, because divergent ecology and sensory perception play an important role in speciation. Geographic comparisons are valuable in determining the factors that influence divergence of acoustic signals. Bats are social mammals and they depend mainly on echolocation pulses to locate prey, to navigate and to communicate. Mounting evidence shows that geographic variation of bat echolocation pulses is common, with a mean 5–10 kHz differences in peak frequency, and a high level of individual variation may be nested in this geographical variation. However, understanding the geographic variation of echolocation pulses in bats is very difficult, because of differences in sample and statistical analysis techniques as well as the variety of factors shaping the vocal geographic evolution. Geographic differences in echolocation pulses of bats generally lack latitudinal, longitudinal and elevational patterns, and little is known about vocal dialects. Evidence is accumulating to support the fact that geographic variation in echolocation pulses of bats may be caused by genetic drift, cultural drift, ecological selection, sexual selection and social selection. Future studies could relate geographic differences in echolocation pulses to social adaptation, vocal learning strategies and patterns of dispersal. In addition, new statistical techniques and acoustic playback experiments may help to illustrate the causes and consequences of the geographic evolution of echolocation pulse in bats.     

重庆市三峡库区柑橘渣的营养物质和苦味物质研究

本文对重庆市三峡库区柑橘渣的营养物质和苦味物质含量进行了系统检测。结果表明,重庆市三峡库区的柑橘渣无氮浸出物、消化能和钙含量较高,氨基酸组成全面,但粗蛋白质和总磷含量低,水分、粗纤维和苦味物质含量高,作为潜在的饲料资源,经过适当处理可以大量开发作畜禽饲料。     

Anatomical and surface ultrastructural investigation of the tongue in the straw-coloured fruit bat (Eidolon helvum,Kerr 1972)

The morphology of tongue in straw-coloured fruit bat from tropical forests was evaluated in relation to frugivorous diets and in comparison with other species that consumes other food types. Gross, stereomicroscopy, scanning electron microscope and histological methods were used. The tongue was relatively long with round tip, which closely fitted into oral cavity. Five types of mechanical papillae included crown-like and trifid filiform papillae. Also bulky, cone-shaped papillae and long conical papillae were identified. These mechanical types also showed variations in shape, size and number of processes of papillae. Transitional forms of these mechanical papillae were present. Fungiform papillae with taste pores were interposed amongst filiform types in apex and body; three ovoid-shaped vallate papillae were in triangular arrangement on root and displayed taste pores. Some bulky, cone-shaped papillae surrounded the vallate papillae. Histologically, mechanical filiform types showed highly keratinized stratified squamous epithelium and dense connective tissue core with secondary papillae. Taste buds appeared in fungiform and vallate papillae. Neutral and acidic secretions were identified in lingual glands of root. The presence of prominent filamentous processes of filiform papillae and conical papillae of the tongue in conjunction with gustatory papillae ensures adaptation to copious fruit diets. The gross morphometric and histometric parameters of the tongue did not differ remarkably from previous values obtained for some fruit bats with comparable weight. This investigation showed similarities with fruit bats such as large flying fox and Egyptian fruit bat and reflect common diet and feeding habits but varied from insectivorous and nectivorous bats.     

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.     

Analyses of free amino acid and taste sensor traits in egg albumen and yolk revealed potential of value-added eggs in chickens

To create high-quality eggs by using different breed and feed materials, we investigated free amino acid contents and taste sensor traits using two chicken breeds (Rhode Island Red; RIR and Australorp; AUS) fed two feeds (mixed and fermented feeds). Two-way ANOVA revealed significant breed and feed main and interaction effects on albumen bitterness and a significant interaction effect on yolk bitterness. Albumen from RIR fed mixed feed and AUS fed fermented feed was higher bitterness, whereas yolk from those groups was lower bitterness. Significant breed effects were detected in four albumen amino acid traits (His, Met, Ile, and Lys) and a yolk His, whereas significant feed effects were found in 15 albumen amino acid traits (Asp, Glu, Ser, His, Gly, Thr, Ala, Tyr, Val, Met, Trp, Ile, Leu, Lys, and Pro) and a yolk cystine trait. Compared to albumen amino acids, yolk amino acids had limited effects by breed and feed. The present results suggest that genetic and nutritional factors can alter not only amino acid contents but also sensor values of bitterness, indicating that selecting the combination of breed and feed enable us to make amino acids enriched and taste added designer eggs in future.     

绵羊β3肾上腺素能受体蛋白结构和分子进化分析

β3肾上腺素能受体(ADRB3)是G蛋白耦联受体超家族的成员之一,主要作用于脂肪组织,参与调节脂肪分解和能量代谢。本文基于NCBI上已经发表的14个物种的ADRB3基因mRNA和蛋白质序列,利用网络信息资源和生物学软件,对绵羊等14个物种进行分子进化分析,为进一步研究其表达调控奠定基础。结果表明:该蛋白包含1段50个氨基酸组成的信号肽,是一种具有7个跨膜区结构的不稳定的疏水性膜蛋白。二级结构由α螺旋(23.95%)、β延伸链(20.49%)和无规则卷曲(55.56%)构成;分子进化分析结果显示,14个物种被分成2支,绵羊、山羊、牛、猪、马、狗、猫、豚鼠、大鼠、小鼠、猕猴、黑猩猩和人聚为一支,虹鳟鱼单独为一支,该聚类结果和公认的动物分类及进化关系吻合;非同义替换率与同义替换率的比值ω为3.756,说明ADRB3基因发生了正向选择,即受自然选择的作用较大。     

Digestive retention times for Allen's swamp monkey and L'Hoest's monkey: data with implications for the evolution of cercopithecine digestive strategy

Primates access energy from plant fiber via bacterial fermentation in either a modified forestomach ('foregut'), a caecocolic ('hindgut') chamber of the large intestine, or both. Longer digestive retention times allow for more complete fermentation; as such, primates that consume an herbivorous diet high in fiber are expected to have both relatively and absolutely longer retention times than those mammals that rely on more readily digestible plant foods, such as fruit. We used particulate markers to measure the digestive retention times of captive Allen's swamp monkeys [Allenopithecus nigroviridis (Pocock, 1907)] (n= 3) and L'Hoest's monkey (Cercopithecus lhoesti P. Sclater, 1899) (n= 2). Results indicate mean retention times of 23.2-29.4 h and 23.2-24.0 h for C. lhoesti and A. nigroviridus, respectively. Results from this study, in combination with previously published data on digestive retention times in other primate species, indicate that cercopithecines differ from other primate taxa by having lengthier retention times that can be predicted by body mass alone. These data are consistent with the hypothesis that relatively lengthy retention times are a primitive trait for Cercopithecinae.     

Preference for inorganic sources of calcium and phosphorus by sheep as a function of need

We hypothesized that ruminants discriminate among different mineral supplements and modify their selection as a function of need. Forty lambs were offered four‐way choices among P, Ca, and Mg sources: monosodium phosphate (MSP), Magnesium phosphate (MGP), Monocalcium phosphate (MCP), and Dicalcium phosphate (DCP); and two‐way choices between DCP and the other mineral sources (Baseline). Subsequently, lambs were randomly assigned to four groups (10 lambs/group) and fed rations such that levels of Ca and P were low (LCa_LP), adequate (NCa_NP), low in Ca and adequate in P (LCa_NP), or adequate in Ca and low in P (NCa_LP). Four‐ and two‐way choice tests were repeated (Post‐deficiency). During Baseline, lambs ate and preferred MSP > MGP>DCP = MCP (p < .0001), showing that they discriminated among minerals. This pattern remained during four‐way Post‐deficiency tests, but lambs in LCa_LP, LCa_NP, and NCa_LP showed increased preference for MCP, MGP, and DCP, respectively, relative to other groups and Baseline (p < .05). Some mineral preference also changed in relation to serum concentration of P and Ca. Thus, lambs discriminated among minerals and some groups modified their preferences from Baseline to Post‐deficiency choice tests, likely influenced by mineral needs, which in turn contributed to rectify mineral imbalances.     

布鲁菌进化和分类学研究进展

布鲁菌属革兰氏阴性兼性胞内寄生菌,能感染多种宿主动物和人。该属可分为6个典型种,包括羊种、牛种、猪种、沙林鼠种、绵羊附睾种以及犬种布鲁菌等。此分类是基于其致病性以及宿主偏好性的差异划分。尽管6个种通过传统表型试验能区分,但布鲁菌种内采用DNA-DNA杂交证明DNA同源性高度一致（相似性大于90%）。因此有人提议布鲁菌由单一种组成,即布鲁菌属中只有羊种布鲁菌,其他种都是羊种菌的生物亚型之一。然而基于其他分子技术的基因分型表明其DNA多态性表现明显,说明目前对这个种的分型还是比较准确。而最近分离的海洋种布鲁氏菌分离株（鳍型和鲸型）采用传统分型标准和一些特异的分子标记也证明这种分型比较正确。本文对目前布鲁菌种属进化和分类学进行综述,希望对研究其进化和分类有所帮助。     

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.     

Preference for inorganic sources of magnesium and phosphorus in sheep as a function of need

We determined whether sheep discriminate among different mineral supplements containing P and Mg and if they modify their selection as a function of the basal diet received. Forty lambs were offered four-way choices among inorganic sources of P and Mg: magnesium oxide in its coarse 1) C-MgO and granular 2) MgO forms and magnesium phosphate: 3) Mag33 (33% Mg and 2.7% P), and 4) MGP (25% Mg and 15% P), and two-way choices between MGP and each of the other minerals, and between MgO and C-MgO (baseline). Subsequently, lambs were randomly assigned to four groups (10 lambs/group) and fed rations such that the levels of Mg and P were low (LMg_LP), adequate (NMg_NP), low in Mg and adequate in P (LMg_NP), or adequate in Mg and low in P (NMg_LP). After 29 d, choice tests (post-deficiency) were repeated. During baseline, lambs ate and preferred Mag33 > C-MgO = MGP > MgO (P < 0.05). This pattern remained during post-deficiency tests, but lambs in LMg_LP and LMg_NP increased their preference for MGP and C-MgO, respectively, whereas lambs in NMg_LP increased their preference for C-MgO and MGP relative to baseline (P < 0.05). The serum concentrations of P and Mg increased after preference tests, and preference for MgO and MGP in low-Mg groups increased as the serum concentration of Mg declined (P < 0.05). Thus, lambs discriminated among different minerals and some groups modified their preferences based on the basal diets received, which rectified mineral imbalances.     

Feeding ecology of four livestock species under different management in a semi-arid pastoral system in South Africa

The Leliefontein communal area in Namaqualand is grazed by mixed species herds that have multiple benefits for pastoralists. This study assessed how the management (herding and free-ranging) of different livestock herds affects their feeding ecology during the wet and dry seasons in a semi-arid shrubland. By using direct observations of livestock grazing in the field, we established their habitat preferences, diet selection and resources overlap. Results indicate that all free-ranging livestock can be considered grazers with cattle being selective. When sheep are herded, they tend to be more generalist feeders and herded goats are browsers. Livestock diet selection and forage preferences are largely linked to the habitats in which they graze and browse. Dietary overlap is highest between free-ranging livestock irrespective of season, whereas herded livestock are able to consume a food source with little potential competition from other livestock. Although the wet-season annual forage resources are able to sustain the livestock population in Leliefontein, this study concludes that the overdependence on annual vegetation would make livestock vulnerable during drought periods when forage production is low.     

猪冠状病毒的起源与遗传演化

冠状病毒变异率高,宿主广泛,主要感染哺乳动物和禽类,严重威胁公共卫生安全与养殖业发展.生猪养殖业中,冠状病毒也是危害猪只健康的重要病原.本研究对4种代表性猪冠状病毒:猪传染性胃肠炎病毒(transmissible gastroenteritis virus,TGEV)、猪流行性腹泻病毒(porcine epidemic...     

6株H9N2禽流感病毒分子进化及对小鼠的致病性

2009年从山东不同地区的规模化肉鸡场中分离到6株H9N2亚型流感病毒,对其分子特征进行分析,发现6株病毒可以分为2个不同的基因型,并且其中一个基因型是CK/SH/F/98（H9N2）和CK/SH/Y2/2008（H9N2）的重组病毒。为阐明H9N2流感病毒对哺乳动物致病性,分别以106 EID50剂量攻毒6周龄BALB/c雌性小鼠,6株病毒都能在小鼠肺脏中复制,而且2株病毒能在攻毒7d后引起小鼠死亡。结果表明,H9N2亚型流感病毒对哺乳动物毒力有增强趋势。     

Impact of macronutrient composition and palatability in wet diets on food selection in cats

Cats are obligate carnivores adapted to high‐protein diets, but are commonly fed diets rich in carbohydrate. The aim of this study was to examine the food intake choices of cats when diets with different protein and carbohydrate contents were offered. Thirty‐nine cats participated in voluntary dietary intake studies. Four foods were formulated to provide between 24% and 53% of metabolizable energy as protein, between 43% and 11% as carbohydrate and holding dietary fat constant with a contribution of approximately 36%. Foods were offered either singly to evaluate voluntary food intake or in pairs to compare food intake between pairs of diets. Cats regulated their macronutrient intake to attain an overall diet composition that provided 53% of metabolizable energy as protein, 11% as carbohydrate and 36% as fat. The protein contribution corresponded to approximately 6 g of protein/kg body weight/day. High‐protein/low‐carbohydrate diets were always eaten preferentially over low‐protein/high‐carbohydrate foods. When low‐protein/high‐carbohydrate diets were offered, cats limited their food intake to limit daily carbohydrate intake to less than 3 g of carbohydrate/kg body weight. This carbohydrate ceiling may limit protein and even energy intake when only low‐protein/high‐carbohydrate diets were offered. The inclusion of palatability enhancer in the diets increased food intake but did not change protein or carbohydrate intake patterns, indicating that macronutrient intake can be regulated regardless of the use of palatability enhancers in cats. We conclude that cats can discriminate between diets based on macronutrient composition and regulate their intake to maintain maximal protein intake but limit carbohydrate intake.     

The presence and distribution of cannabinoid type 1 and 2 receptors in the mandibular gland: The influence of different physical forms of diets on their expression in piglets

We explored the expression and cell type distribution of cannabinoid receptors type 1 (CB1) and cannabinoid receptors type 2 (CB2) in the mandibular glands of pigs in relation to different physical forms of the diet. Thirty‐two crossbred growing pigs (ages 5–6 weeks) were randomly allotted to four experimental groups (eight pigs/group) and fed four different physical types of the same diet for 4 weeks: finely ground pellet (FP), coarsely ground meal (CM), coarsely ground pellet (CP) and coarsely ground extruded (CE) with dMEAN of 0.46, 0.88, 0.84 and 0.66 mm respectively. At the end of the feeding trial, the pigs were euthanized and the mandibular gland was collected after dissection. By immunohistochemistry, positive signals for CB1 were found in the cytoplasm of duct epithelial cells of pigs fed CP, FP and CE diets and in the serous cells of mixed acini in pigs fed the coarser CM diet. Positive signals for CB2 were detected in duct epithelial cells and in neurons of ganglia close to major secretory ducts of all pigs. The differential expression and localization of these receptors in response to variable chewing activity due to the type of diet suggest that endocannabinoids may influence the functional activity of the mandibular gland by modifying qualitative and/or quantitative aspects of salivary secretion.