Here we describe the expression of two novel transcripts, Ende (AK014119) and Npe (AK084355), during early mouse embryogenesis. Ende mRNA was first detected at embryonic day (E) 7.0 in a small population of epiblast cells in the distal half of the embryo. At E7.5, Ende was expressed by newly formed definitive endoderm cells in the proximal half of the embryo, and was not expressed in extra-embryonic endoderm. This expression pattern then changed to the ventral aspect of the developing foregut pocket and the entire hindgut pocket at E8.0-8.5, before becoming restricted to the foregut overlying the heart and the posterior most hindgut. By E9.0 Ende expression was also observed in the posterior half of the ventral neural tube. Thus, Ende was expressed dynamically and in specific populations of the definitive endoderm from E7.0 to E8.5. We found Npe expression to be restricted to the node/posterior notochord region at the distal tip of the embryo between E7.0 and E8.0. By E9.5, Npe expression was observed in the posterior most population of dorsal hindgut cells and notochord cells. Given their expression in mouse definitive endoderm populations, Ende and Npe will be valuable tools to study formation and development of this tissue.

Drosophila melanogaster is a fruit fly that is one of the most commonly used animal model for genetic studies. Dorsal-ventral (dv) patterning, which is the body plan, of the Drosophila embryo is determined by the asymmetric positioning of different underlying cellular molecules. DV patterning of the Drosophila embryo is established well before fertilisation. The Drosophila egg develop within a cluster of cells consisting of an oocyte interconnected with fifteen sister nurse cells, which function as a source of RNAs and proteins for the developing oocyte and degenerate by the end of oogenesis. Surrounding this cluster is an epithelium of follicle cells, which provide yolk and secrete the eggshell (Fig1). Initial dv asymmetry is established at mid oogenesis and the information is then passed on to the surrounding follicle cells (3). The protein gurken (grk), in the oocyte, provides the initial polarizing signal to initiate the formation of the eventual polarity of the egg, and activates Drosophila epidermal growth factor receptor (EGFR) signaling in the dorsal follicle cells. Through positive and negative feedback mechanisms, this EGF signaling is refined and defines a precise pattern of cell fates within the follicular epithelium (3). This specific definition of fates will be used as a basis to understand the effects of the gene capicua (cic) on follicle cell fate patterning.

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