Functional And Evolutionary Study On Cone Visual Pigments Of Bats

Chiroptera(commonly named as: bats)is the second largest group of extant mammals.Bats mainly roost in caves or dense bushes and come out to feed at night,morning and evening,so the study of bat senses has been a hot topic in research.Bats are nocturnal,so it is of interest what role the short wavelength sensitive 1(SWS1)and medium/long wave sensitive(M/LWS)genes,which regulate their color vision,can play in the nocturnal lifestyle of bats.In the past,some studies have suggested that constant-frequency echolocation bats have lost the SWS1 gene due to sensory trade-off between vision and echolocation,and that some cave-dwelling Old World fruit bats have lost the ability to see ultraviolet light due to prolonged survival in dark environments.In addition,functional validation has shown that some bats are sensitive to UV light,but more representative bats are needed to be verifiedy.Therefore,in this stydy,we first analyzed the SWS1 and M/LWS genes and constructed a species tree of bats using bioinformatics methods,and then selected some representative bats for in vitro experiments.The first part of this thesis is a molecular evolutionary study and functional validation for UV vision in bats.We downloaded the SWS1 gene sequence of bats from the NCBI database,analyzed it using bioinformatics methods and constructed a species tree,and found that the SWS1 gene has an important role for bats.Seven representative bat were selected for in vitro experiments based on the analysis results,among which the special one was Mystacina tuberculata.We used Leptonycteris yerbabuenae,which has a complete SWS1 gene sequence,to complete the missing sequence of Leptonycteris yerbabuenae,and constructed a chimera sequence of L.eptonycteris and M.tuberculata,and verified it in functional experiments.The experimental results showed that the SWS1 visual pigments of six representative bat were sensitive to UV light with maximum absorption wavelengths between 351 nm-360 nm,and the SWS1 visual pigment of the M.tuberculata was not functional.The second part of the thesis is a molecular evolutionary study and functional validation for red/green color vision in bats.We downloaded the M/LWS gene sequences of bats from the NCBI database,analyzed them using bioinformatics methods and constructed a species tree of bats,and found that the bat M/LWS genes are highly conserved during their evolution.Based on the results of the analysis,seven representative bat were selected for in vitro validation experiments,and the experimental results showed that the M/LWS pigments of the seven representative bat species were functional with a maximum absorption wavelength range of 539nm-556 nm.The above results indicated that red/green senses had an important role for these seven bat.The SWS1 visual pigment and M/LWS visual pigment functions were verified in Phyllops falcatus,Tonatia saurophila and Tadarida brasiliensis,and both SWS1 and M/LWS visual pigments were found to be functional in these three bat species,indicating that color vision is important for these three bat.In this thesis,the SWS1 gene and M/LWS gene were analyzed by bioinformatic techniques,and then in vitro experiments were conducted to verify that UV vision has an important role in these bat,and the M/LWS visual pigment is functional in all of these bats,and color vision was also found to have an important role in three of them.Whether the loss of function of the M.tuberculata visual pigment is related to changes in key amino acid sites or whether the chimera has an effect on its SWS1 visual pigment function needs to be verified in subsequent experiments.The present study reveals the function,evolutionary history and molecular mechanisms of visual pigments(SWS1 and M/LWS)in the evolution of bats,and provides a theoretical basis for future sensory evolution of bat vision.