Transcriptome Sequencing Analysis Of Oviduct Tissues From Pre-laying And Laying Hens And The Study Of New Gene OvoDB?

The oviduct is an important part of the female reproductive system.Chicken oviduct is not only the place where the fertilized egg is formed,but also the part where the egg white and the eggshell are formed.Studies have shown that egg white and eggshells contain antibacterial ingredients such as avian defensins that not only protect the eggs from invasion by pathogenic microorganisms in the natural environment,but also enhance the immunity of the embryos.In this study,transcriptome sequencing analysis was performed on the pre-laying and laying hens in the magnum and eggshell gland regions of the oviduct.The results are listed below:1)In total,1579 new genes were discovered but only 803 of them were functionally annotated in databases.2)Between pre-laying and laying hens,1040 and 595 genes were differentially expressed in the magnum and uterus tissues respectively.Differentially expressed genes annotation results show that the highexpressed genes in the magnum and uterus of pre-laying hens are mainly related to growth and development,including cell division,DNA replication and repair and metabolic correlations.However,genes highly expressed in oviduct tissues of laying hens are closely related to transmembrane transport,mineral ion transport,protein modification and organism defense.3)In addition,this study also focused on the expression of defensins in the laying hens' oviduct tissues.Results indicated that three members of the avian beta defensins?Av BD4,Av BD10 and Av BD11?and all ovodefensin genes are only expressed in the tubal magnum region of laying hens.While,Av BD12 was not distinct differentially expression in magnum or eggshell regions of the two groups of chickens,whereas other Av BDs were hardly expressed in any examined chicken oviduct tissues.Above results indicated that the transcriptional expression level of oviduct tissues between pre-laying and laying hens were obvious dfferent;Av BD4,Av BD10,Av BD11 and ovodefensins are most likely produced by the oviduct and secreted into eggs.4)Furthermore,based on screening and analysis of sequencing data,we found a novel gene?ID: Gallus_gallus_new Gene₁845?,which share the same expression pattern with the ovodefensin genes.Then the full-length sequence cloning,sequence analysis,tissue expression studies,structural analysis,and phylogenetic analysis of this gene were conducted,and results confirmed that this new gene is another new chicken ovodefensin member,firstly named OvoDB? in this paper.In vitro antibacterial studies showed that OvoDB? would inhibit E.coli?CICC23657 strain?rather than S.aureus?1679a strain?.In summary,there are manynew transcripts and differentially expressed genes in the oviduct tissues between pre-laying and laying hen;while,some of these genes have not yet been annotated and still need further excavation.Some avian beta defensins and all ovodefensins were probably produced by chicken oviduct tissues and secreted into the eggs.This study identified the OvoDB? ovodefensin gene for the first time and found that it has an inhibitory effect on E.coli.This paper provides the basis for further research of defensins about chicken oviduct and eggs.