THE ROLE OF FS(1)K10 IN THE LOCALIZATION OF THE MESSENGER-RNA OF THE TGF-ALPHA HOMOLOG GURKEN WITHIN THE DROSOPHILA OOCYTE

A critical step in Drosophila dorsoventral patterning is the movement of gurken mRNA from the anterior cortex of the oocyte to the oocyte's anterodorsal corner at stage 8 of oogenesis. Such movement is dependent on fs(1)K10. It has been proposed that Ss(I)K10 mediates gurken mRNA movement by down-regulating gurken mRNA levels, thus ensuring that gurken mRNA does not saturate its receptors located in the oocyte's anterodorsal corner. In contradiction to this model, we show here - both genetically and immunocytochemically - that GRK protein levels are lower in the anterodorsal region of fs(1)K10 mutant oocytes than in the anterodorsal region of fs(1)K10(+) oocytes. From this and other data, we propose a more direct role for fs(1)K10 in the gurken mRNA localization process.