Molecular dissection of Vasa sequences required for oocyte posterior localization and germ-plasm assembly in the fruit fly Drosophila melanogaster

• Main Authors: Szu-Chieh Wang, 王思捷
• Other Authors: Ming-Der Lin
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/78323774835545377289

碩士 === 慈濟大學 === 生命科學系碩士班 === 99 === Vasa is a highly conserved protein and essential for germline development in metazoan. In Drosophila, the posterior germ plasm localization of Vasa (DmVasa) is mainly dependent on its interaction with Oskar (Osk). Till now, osk homolog genes had been only found in a few insects of the orders Diptera and Hymenoptera. Acyrthosiphon pisum (Hemiptera) Vasa protein (ApVasa) had been found to localize in the primordial germ cell, and is a component of germ plasm as Drosophila Vasa. As there is no osk homolog in Acyrthosiphon pisum, the germ plasm localization mechanism of ApVasa might be different from that of DmVasa. Here, we used Drosophila egg chamber as a model system to investigate the germ plasm localization and determination mechanisms of Vasa protein by swapping the N- and C-terminal domains between DmVasa and ApVasa. We intented to know whether Vasa functional motifs required for germ plasm assembly and germ plasm localization are different among speciese. The diciphering of the Vasa functional motifs could help us to understand the detailed macheanism of germ cell formation. According to our results, we hypothesize that stable germ plasm localization of DmVasa at st 9 to st 10 is dependent on the N-terminal region of DmVasa containing Fsn, Gus and Osk interaction motifs. In addition, this region is also function to assemble the functional germ plasm required for abdomen formation. Here, we also identified a novel and essential Vasa germ plasm localization motif which is located in the amino acid 447 to 493 of C-terminal conserved region. This region can also direct Vasa germ plasm localization after stage 11 by an as-yet-unknown mechanism.