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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2008.07.033 Byline: Ming-Der Lin (a), Xinfu Jiao (b), Dominic Grima (c), Sarah F. Newbury (c), Megerditch Kiledjian (b), Tze-Bin Chou (a) Keywords: Processing bodies; Drosophila decapping protein 1; Drosophila decapping protein 2; Pacman; Me31B; Oogenesis Abstract: Processing bodies (P-bodies) have emerged as important subcellular structures that are involved in mRNA metabolism. To date, a detailed description of P-bodies in Drosophila oogenesis is lacking. To this end, we first demonstrate that Drosophila decapping protein 2 (dDcp2) contains intrinsic decapping activity and its enzymatic activity was not detectably enhanced by Drosophila decapping protein 1 (dDcp1). dDcp1-containing bodies in the nurse cell cytoplasm can associate with the 5' to 3' exoribonuclease, Pacman in addition to dDcp2 and Me31B. The size and number of dDcp1 bodies are dynamic and dramatically increased in dDcp2 and pacman mutant backgrounds supporting the conclusion that dDcp1 bodies in nurse cell cytoplasm are Drosophila P-bodies. In stage 2-6 oocytes, dDcp1 bodies appear to be distinct from previously characterized P-bodies since they are insensitive to cycloheximide and RNase A treatments. Curiously, dDcp2 and Pacman do not colocalize with dDcp1 at the posterior end of the oocyte in stage 9-10 oocytes. This suggests that dDcp1 bodies are in a developmentally distinct state separate from the 5' end mRNA degradation enzymes at later stages in the oocyte. Interestingly, re-formation of maternally expressed dDcp1 with dDcp2 and Pacman was observed in early embryogenesis. With respect to developmental switching, the maternal dDcp1 is proposed to serve as a marker for the re-formation of P-bodies in early embryos. This also suggests that a regulated conversion occurs between maternal RNA granules and P-bodies from oogenesis to embryogenesis. Author Affiliation: (a) Institute of Molecular and Cellular Biology, College of Life Science, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (b) Department of Cell Biology and Neuroscience, Rutgers University, 604 Allison Road, Piscataway, NJ 08854-8082, USA (c) Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, BN1 9QG, UK Article History: Received 27 February 2008; Revised 14 July 2008; Accepted 15 July 2008

The production of female germline chimeras is invaluable for analyzing the tissue specificity of recessive female sterile mutations as well as detecting the maternal effect of recessive zygotic lethal mutations. Previously, we developed the 'FLP-DFS' technique to efficiently generate germline clones. This technique uses the X-linked germline-dependent dominant female sterile mutation [ovo.sup.D1] as a selection for the detection of germline recombination events, and the FLP-FRT recombination system to promote site-specific chromosomal exchange. This method allows the efficient production of germline mosaics only on the X chromosome. In this paper we have built chromosomes that allow the use of this technique to the autosomes. We describe the various steps involved in the development of this technique as well as the properties of the chromosomes utilized.

The receptor tyrosine kinase (RTK) torso stimulates the D-Raf without the presence of Ras1. The RTK expresses transcription factors for tailless and huckebein. The activity of D-Raf is tested without the exchange factor Son of sevenless (Sos) and the adaptor protein drk (Grb2). It is also tested by the phenotypic mutation of D-Raf that binds Ras1 to D-Raf. RTK signal pathways exist from membrane to nucleus in both vertebrates and invertebrates.

Suppressor-of-white-apricot (su(w(a))) gene expression is autoregulated during pre-mRNA synthesis. Su(w(a)) protein controls the level of fully spliced su(w(a)) pre-mRNA levels. The fully spliced su(w(a)) mRNA encodes the su(w(a)) protein, and su(w(a)) pre-mRNA contains by-products of the autoregulation process. Maternal su(w(a)) spliced mRNA is accumulated during oogenesis due to the function of su(w(a)) expression.

The production of germline chimeras has usually involved the use of x-ray irradiation to recover germline mosaics in individuals heterozygous for dominant female sterile (DFS) mutations. This technique gives low frequencies of recovery of mosaic females. However, by using the yeast recombinase, FLP, to induce site-specific homologous mitotic recombination in flies heterozygous for a DFS mutation, more that 90% of mosaic females are recovered. This technique, termed the 'FLP-DFS' technique, was used to analyse the maternal effect phenotypes of a large number of X-linked zygotic lethal mutations.

Examines the autoregulation at the level of pre-messenger RNA (mRNA) splicing of the suppressor-of-the-white-apricot [su(wa)] gene in Drosophila. Regulation of somatic RNA processing events by the protein encoded for by the gene; Autoregulation of the gene at the level of pre-mRNA splicing reported; Mechanism of splicing regulation and developmental control of genetic expression.