Cloning And Characterization Of Novel Isoforms Of Boule Gene In Bats (Chiroptera)

Bats are the second biggest group of mammals and have many special reproductive phenomina.Many species of bats have gotten the ability of sperm storage,which is associated with sperm motility appraisal including quality,quantity and time three parameters,to adapt harsh environment and even posterity prosperous.To keep this special strategy,bats had developed the efficient mechanism of sperm storage. Spermatogenesis is a complex process subject to strict controls of a multitude of genes. Data showed that BOULE gene is a key factor in controlling the meiosis of male germ cells,and can regulate the expression of twine gene,which promotes progression through meiosis.To test whether and how BOULE gene participate in bat sperm storage,the complete coding domain sequences(CDS) of BOULE gene were cloned and analyzed from four bat species(Order Chiroptera),including Myotis ricketti and Rhinolophus ferrumequinum which have the ability of sperm storage,and Eonycteris spelaea and Rousettus leschenaultii which no exactly proof indicate that they have tbis ability.Our data indicated that bat BOULE gene have at least two isoforms(a and b) by alternative splicing.Isoform a is common to that of other species BOULE gene,however,isoform b is specific in bats and is the first time to be identified.As the difference of exons lost, BOULE gene isoform b of bats have a premature stop codon in different position and have different length of CDS,thus,some of them lost the functional domain.Then, selected pressure analysis on BOULE gene was carried out based on the common isoform (a) of 19 mammalian species including four bat species.Data indicated that BOULE gene was under the purified selection during the evolution of mammals and no significant difference of selected pressure between bats and other mammals was found.Thus, BOULE gene may participate in the regulation of bat sperm storage by differential expression of different isoforms.In this study,for the first time,we cloned the multiple transcript variants of bat BOULE gene and identified the novel isoforms.Together with the evolutionary analysis,our data indicated a new potential regulation mechanism of BOULE on bat spermatogenesis.