3-6-13_germ cells and germ plasm

However their function and segregation mechanisms are

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Unformatted text preview: e. However, their function and segregation mechanisms are not fully understood (2, 3). To monitor P granule dynamics, we used confocal microscopy to image live embryos expressing the P granule protein PGL-1 fused to green fluorescence protein (GFP) (4). We obtained similar results with GFP fusions to two other P granule proteins PGL-3 and GLH-1 (5, 6). In the live movies, we analyzed granule dynamics (number, size, and movement) and the overall distribution of each protein by quantifying total (granular + diffuse cyto- offspring of par-3 mutant mothers have symmetric P granule distribution *These authors contributed equally to this work. (courtesy Ken Kemphues) Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Center for Cell Dynamics, Johns Hopkins School of Medicine, 725 North Wolfe Street, PCTB 706, Baltimore, MD 21205, USA. †To whom correspondence should be addressed. E-mail: gseydoux@jhmi.edu 17 DECEMBER 2010 1685 Germ cells are transcriptionally repressed pes-10 mRNA is not found in P2 Pole cells are the germ cell precursors in Drosophila anterior posterior pole cells Pole cells contain pole plasm, the fly equivalent of germ plasm in other organisms. They are first cells to form in the embryo. pes-10 mRNA Gilbert 9e, Fig. 16.3b Gilbert 9e, Fig. 16.2 Pole plasm transplant can rescue the ability to make pole cells Pole cells in Drosophila: pole plasm can be transplanted needle needle pole plasm removed from donor embryo pole plasm injected into embryo derived from a UV irradiated egg (can’t make pole cells normally) See Gilbert 3e, Fig. 7.32 wildtype: makes pole cells UV treated + pole plasm transplant: pole cells Conclusion: Pole plasm contain a localized determinant sufficient for pole cell (germ cells) production Gilbert 3e, Fig. 7.32 Pole plasm in Drosophila really does act as a determinant Step 1: transplant pole plasm to ANTERIOR of recipient embryo of different genotype Pole plasm in Drosophila really does act as a determinant Step 2: transplant pole cells that form to another embryo of third genotype The induced pole cells can’t make it to the gonad, so we transplant them into a third type of embryo to see if they function This makes sure that the transplant didn’t involve any DNA from the “pink” cytoplasm...
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