Speckle distribution of a putative RNA helicase, ME31B during oogenesis. A. Nakamura 1, R. Amikura 1, S. Kobayashi 1,2,3. 1) Inst. Biol. Sci; 2) Gene Experiment Center; 3) TARA Center, Univ. Tsukuba, Tsukuba, Ibaraki, Japan.
Embryoonic patterning in Drosophilais regulated by maternal factors that are localized asymmetrically within eggs. Many of such factors become localized as mRNAs, and their translation is also regulated spatially and temporally. Presumably, translocation and subsequent translation of these mRNAs are regulated by trans-acting molecules that bind to the target mRNAs to form RNP particles. In order to isolate genes encoding protein involved in these processes, we screened proteins which distribute in a speckle pattern during oogenesis. We made transgenic flies with an ovarian cDNA library, in which GFP-cDNA fusion genes are expressed under the control of vasapromoter. Spatial distribution of GFP-fusion proteins in oogenesis were observed under a confocal microscope. Screening ~3000 independent transgenic flies, we found that ME31B protein, which has been identified as an oogenesis specific DEAD-box protein, showed speckle signal in the cytoplasm of both nurse cells and oocytes. This distribution pattern is essentially identical to the reported EXUPERANTIA distribution, suggesting that ME31B is a component of sponge bodies, a subcellular structures that are proposed to function in transport and localization of mRNAs in oocytes. We have isolated deletion mutants in me31Blocus by an imprecise P-element mobilization, and are currently analyzing the effects of loss of me31Bfunction on oogenesis. Detailed analyses for the me31Bmutant phenotypes will be presented.