Expression data from additional molar germs at stages of early development in miniature pigs

We identified the spatiotemporal pattern of cascade initiation of additional molars in miniature pig,where second molar (M2) initiated from the posterior-free end of the dental lamina over the first molar (M1) at E60 when M1 progressed to the late bell stage. Similarly, third molar (M3) budded off from the posterior-free end of the dental lamina over M2, which reached bell stage at PN20. However, the molecular mechanisms of the regulatory network during sequential formation of additional molars remain poorly characterized in diphyodont mammals. We performed microarrays on miniature pigs at three molar developmental stages to examine their differential gene expression profiles and potential regulatory networks during additional molar morphogenesis. Miniature pigs' additional molar germs samples from early developmental stages at E50, E60 and E70 were selected for RNA extraction and hybridization on Affymetrix microarrays in biological triplicates. The differentially expressed genes between the 3 different stages were screened, then differentially expressed genes with significance were chosen for significant GO and pathway enriching. The differential genes and functions with significant expression tendencies were predicted using STC for further Path-Net, Signal-Net and Dynamic-Gene-Net analysis for Signal-Net to determine significant pathways and identify the key differentially expressed genes during early additional molars development. Additional molar germs from three key stages were chosen to determine the spatiotemporal control mechanisms of cascade initiation of these molars. The E50 stage corresponding to M1 at cap stage without M2 initiation and the E60 stage targeting M1 at bell stage followed by M2 initiation. The E70 stage as a control, when M1 progresses to late bell stage but M2 changes little.