Mago Nashi and Tsunagi/Y14, respectively, regulate Drosophila germline stem cell differentiation and oocyte specification

consisting of Mago Nashi and Tsunagi/Y14 is required to establish the major body axes and for the localization of primordial germ cell determinants during Drosophila melanogaster oogenesis. The Mago Nashi:Tsunagi/Y14 heterodimer also serves as the core of the exon junction complex (EX), a multiprotein complex assembled on spliced mRNAs. In previous studies, reduced function alleles of mago nashi and tsunagi/Y14 were used to characterize the roles of the genes in oogenesis. Here, we investigated mago nashi and tsunagi/Y14 using null alleles and clonal analysis. Germline clones lacking mago nashi function divide but fail to differentiate. The mago nashi null germline stem cells produce clones over a period of at least I I days, suggesting that mago nashi is not necessary for stem cell self-renewal. However, germline stem cells lacking tsunagilY14 function are indistinguishable from wild type. Additionally, in tsunagilY14 null germline cysts, centrosomes and oocyte-specific components fail to concentrate within a single cell and oocyte fate is not restricted to a single cell. Together, our results suggest not only that mago nashi is required for germline stem cell differentiation but that surprisingly mago nashi functions independently of tsunagilY14 in this process. On the other hand, Tsunagi/Y14 is essential for restricting oocyte fate to a single cell and may function with mago nashi in this process. (c) 2007 Elsevier Inc. All rights reserved.