Identification And Analysis Of Chemoreceptors Of Bombus Lantschouensis

Chemoreception is an important for the communication of insects with the outside world as well as performing social behavioral activities within a colony.Different chemoreceptors play different key roles.Likely,odorant receptors(Ors)are responsible for the recognition of different smell from outside environment,looking for food,and avoid the injury from the outside world.Gustatory receptors(GRs)usually act on the identification of soluble stimulants,initiate innate sexual and reproductive responses.Ionotropic receptors are present in the neurons of olfactory and taste organs and as their ligands of ORs and GRs they help to activate the action potential of the cells.Analysis of the chemoreceptor's receptor family is very important to understand the feeding preference,living habits and social behavior of Bumblebee.In our current study we tried to identify characterize the chemoreceptor receptors of Bombus lantschouensis.The principle results are as follows:(1)Identification and analysis of Odorant receptors(ORs)Ors gene sequences of Bombus terresters and Apis mellifera ligustica were used to query the genome of Bombus lantschouensis by use BLAST.One hundred and sixty-five ORs were identified from the genome of B.lantschouensis,including an Orco,5 pseudogenes and 159 ORs.Gene structure analysis showed that the number of exon for these ORs was from 4 to 9.According to the gene structure,it was classified into 10 groups.The number of subgroup members was about 10 except in Or1-38,Or69-85 and Or128-164(38,27 and 36 members respectively).Conserved motif 2,3 and 4 was found in all members.While Or1-38 and Or39-46 had all predicted motifs.Phylogenetic analysis showed that ORs family was classified into 5 subfamilies.Some ORs of Apis and Bombus clustered separately among different branches indicated that ORs had species-specific loss or expansion.(2)Identification and analysis of Gustatory receptors(GRs)A total of 23 gustatory receptors genes of B.lantschouensis were identified by use BLAST,including 4 pseudogenes and 19 functional receptors.The number of exon receptors varied widely,ranging from 3-11.Sequence analysis showed that Gr4,Gr8,Gr9,Gr14-18 and Gr20 contained 3 exons and had the first exons and their protein sequences had similar conserved motifs,the motif 7 is unique of these sequences.Gr7,Gr12,Gr19 and Gr21-23 contain 6 exons,and their protein sequences have the same conserved motif,where motifs 8 and 10 are specific motifs.Phylogenetic analysis showed that the number of GR family in the bees was significantly less than that of Drosophila.Gr1 and Gr2 are clustered together with the sugar receptor branches of Drosophila.Compared to bees,the branch of AmGr8,AmGr9 is expanded to 8 genes in Bombus,but the function is not yet clear,perhaps related to the more diverse nest-building habits of bumblebees.(3)Identification and analysis of Ionotropic receptors(IRs)Twenty-two ionotropic receptors of B.lantschouensis were identified,which contained 6 antennal IRs and 16 species-specific divergent IRs,IR25 a and IR8 a are co-receptors.The number of exon populations is ranging from 1 to 15,the gene structure was significantly different.There is no obvious feature between other sequence gene structures.Ir8 a,Ir25a.1,Ir25 a.2 contain the same 8 motifs,and the lack of motif 8 and motif 10,Phylogenetic analysis showed that Ir76 b,Ir93a and Ir68 a in D.melanogaster,A.mellifera,B.terrestris and B.lantschouensis were clustered together,indicating that the 4 family members were conserved among species,Ir328-339 is a unique extension of the family in bees,Ir332 had a paralog in Bombus,numbered IR333,which has been lost from A.mellifera.Numbers,gene structure and phylogenetic relationships of Chemoreceptor receptors from the genome of B.lantschouensis were clarified in current study.Conserved motif analysis indicated that motif was missing during the evolution of Chemoreceptor receptors family among bees.These results would provide an important information for exploring the gene evolution and function of Chemoreceptor receptors in future.