| Abstract:In nature,bitter taste substance generally means poisonous for animals,which can give rise to aversive response.Taste provides sensory information to recognize poisonous substances and maintains nutrition balance for animals,thus it decides animals feeding.Taste is divided into five kinds of forms:sweet,sour,bitter,salty,and umami.Mammals identify taste because of the combination of outside substances and taste buds of gustatory papillae on the tongue surface,which give rise to cascade reaction and results in nerve cells impulse.Nerve impulse reach to the cortex of brain and then causes the formation of flavor.Previous studies indicated that chicken has only three bitter taste receptor genes compared with 25 of humans,while it dose not affect chicken to identify bitterness substances,which may due to the abundant genetic diversity of bitter taste receptor gene family.The mechanisms of chicken to identify bitterness substances are still unclear at present,thus it is very meaningful to study on the genetic diversity and function of bitter taste receptor gene family in chicken.In this experiment,we studied the genetic diversity and tongue gene expression of bitter taste receptor gene Tas2rs in chicken by using PCR,RT-PCR.In order to determine if Tas2rs was reacting to outside stimuli of different concentration of several bitterness substances or not,we conducted a preliminary screening from bitter taste receptor gene family.In vitro test,we made Tas2rs gene express heterologously in HEK-293T cell line.In ordrer to explore whether chicken were sensitive to the different concentration of several bitterness substances or not,we finally determined to study the sensibility of receptor proteins to bitterness substances.Here follow the conclusions.(1)Bitter taste receptors gene Tas2r1,Tas2r2,Tas2r3 has 13,3,8 SNP loci,respectively.There were 19 haplotypes of Tas2r1(H1-H19).5 haplotypes of Tas2r2(HA1-HA5)and 13 haplotypes of Tas2r3(HE1-HE13).In addition,the population of Tibetan chicken and JiuYuan black chicken population had shared haplotype with red jungle fowl.which is consisted with the conclusion that chicken originated from jungle fowl.The H1 and HE1 haplotypes were positively with altitude,while H4 and HE4 haplotypes were negatively with altitude.(2)In the individual test,after treated with 5mM,1mM,0.1mM,10-3mM DL-camphor on taste buds in tongue tissues of chicken,Tas2r3 expression is significantly higher than the blank control group treated with 50mM KCL;While in the other three groups treated with 1mM,0.1mM,10-3mM,10-5mM chloramphenicol,quinine,and parthenolide respectively,the expression of Tas2r3 is not significant with the blank control group.The conclusion indicated that Tas2r3 played a leading role in bitterness perception of chicken.(3)In the vitro test of Tibetan chicken population,after simulating by bitterness substances such as 0.1mM,10-3mM DL-camphor;10-3mM Chlorphenamine Maleate;10-3mM erythrocin;10-3mM quinine;0.1mM,10-3mM parthenolide,the mRNA expression of PLC?2?ITPR3 in HEK-293T cell line were significantly higher than KZ control group;In the JiuYuan black chicken population,the mRNA expression of PLC/?2?ITPR3 in HEK-293T cell line were significantly higher than KZ control group stimulated by 0.1mM DL-camphor.The results showed that chicken taste buds are sensitive to different concentration of bitterness substances.Whether the different concentrations of bitterness substances identified in this experiment is really sensitive to chicken,it is supposed to use corresponding experimental instruments to measure calcium concentration further.In conclusion,the nucleotide diversity of Tas2r3 gene contribute to chicken in perceiving bitterness substances of great importance.Whether the different concentrations of bitterness substances identified in this experiment is really sensitive to chicken,we need further verification. |
PDF Full Text Request