Comparative Analysis Of The Tongue Transcriptomes In Three Species Of Bats

As an important organ of animals,the tongue not only plays a crucial role in food intake,food digestion,taste perception,food selection and immune systems,but also helps animals adapt to their living environments using its specialized functions.Different food items contain different kinds of nutrients,and some food items even contain toxic substances,such as alkaloids in plant tissues and defensive secretions released by insects.As one of the first organs exposed to food,we hypothesize that genes associated with food digestion that are expressed in tongue would show expression differences among species with different diets.The diets of bats are complex and diverse,bats are thus ideal study subjects for exploring the evolution of dietary changes.Here,we selected three species of bats:herbivorous bat Eonycteris spelaea and insectivorous bats Rhinolophus sinicus and Myotis ricketii.The tongue transcriptome data of these three bats were generated by RNA sequencing technology.Through comparing the transcriptome data from the three species,we found 257 genes to be highly expressed in all three bats.Among these genes,some genes(e.g.GLUL and LCN2)have immune functions,suggesting that the acquisition of tongue immunity may be related to the highly expressed genes;some genes(e.g.RACK1)have regulatory functions,and some genes(such as PDK4)are related to the growth and metabolism of organisms,indicating that these genes have an indispensable role in maintaining the normal function of the tongue.By screening differentially expressed genes of these three bats,we found that a total of 239 genes are highly expressed in Eonycteris spelaea relative to Rhinolophus sinicus and Myotis ricketii.Some differentially expressed genes(e.g.CHST3 and GAL3ST4)are involved in the metabolism of carbohydrates,suggesting that these genes may be involved in digestion.Further GO enrichment analysis of these differentially expressed genes reveals that certain genes enriched in the "biological process" items are involved in the metabolism of carbohydrates,and some genes enriched in "molecular function" items are also involved in the metabolism of carbohydrates.The results of the GO enrichment analysis further indicate that these genes are related to the metabolism of carbohydrates.This study not only enriches the transcriptome resources of bat,but also confirms that the genes associated with diets show significant expression differences among species with different diets.However,this study is preliminary,future work involving in broad sampling,fluorescent quantitative PCR verification and functional differences of digestive enzymes will help to reveal the molecular basis of dietary diversification in bats.