Axis formation during Drosophila oogenesis

European Molecular Biology Laboratory, Meyerhofstrabetae 1, Postfach10.2209, D-69012, Heidelberg, Germany.
Current Opinion in Genetics & Development (Impact Factor: 8.57). 09/2001; 11(4):374-83. DOI: 10.1016/S0959-437X(00)00207-0
Source: PubMed

ABSTRACT Recent advances shed light on the cellular processes that cooperate during oogenesis to produce a fully patterned egg, containing all the maternal information required for embryonic development. Progress has been made in defining the early steps in oocyte specification and it has been shown that progression of oogenesis is controlled by a meiotic checkpoint and requires active maintenance of the oocyte cell fate. The function of Gurken signalling in patterning the dorsal-ventral axis later in oogenesis is better understood. Anterior-posterior patterning of the embryo requires activities of bicoid and oskar mRNAs, localised within the oocyte. A microtubule motor, Kinesin, is directly implicated in localisation of oskar mRNA to the posterior pole of the oocyte.

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    • "In Drosophila, the anterior–posterior (AP) and dorsal–ventral body axes are determined in the developing oocyte during oogenesis . Establishment of these axes depends on cytoskeletal organization and localization of several important maternal determinants at different subcellular regions of the oocyte (Riechmann and Ephrussi, 2001; van Eeden and St Johnston, 1999). For example, the transforming growth factor a homolog Gurken (Grk) plays two essential roles in these processes. "
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    ABSTRACT: Vesicle trafficking plays a crucial role in the establishment of cell polarity in various cellular contexts, including axis-pattern formation in the developing egg chamber of Drosophila. The EGFR ligand, Gurken (Grk), is first localized at the posterior of young oocytes for anterior-posterior axis formation and later in the dorsal-anterior region for induction of the dorsal-ventral (DV) axis, but regulation of Grk localization by membrane trafficking in the oocyte remains poorly understood. Here, we report that Syntaxin-1A (Syx1A) is required for efficient trafficking of Grk protein for DV patterning. We show that Syx1A is associated with the Golgi membrane and is required for the transportation of Grk-containing vesicles along the microtubules to their dorsal anterior destination in the oocyte. Our studies reveal that the Syx1A dependent trafficking of Grk protein is required for efficient EGFR signaling during DV patterning.
    Developmental Biology 11/2012; 373(2). DOI:10.1016/j.ydbio.2012.10.029 · 3.64 Impact Factor
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    • "Based on GO annotations, we found many interesting RPW genes that are involved in regulating neuron development, such as Discs large (dlg), playing important roles in synapse remodeling during metamorphosis (Liu et al., 2010), and Glass bottom boat protein (gbb), a known BMP ligand that is important for motoneuron development(James & Broihier, 2011). We identified genes involved in dorso-ventral axis formation (Riechmann & Ephrussi, 2001), such as egfr, sos, and piwi. Other interesting genes are juvenile hormone (JH) and ecdysone, the two most important hormones regulating insect development (Andres et al., 1993; Robbins et al., 1968; Grieneisen, 1994), as well as chitin deacetylase genes, playing critical role in modifying extracellular chitin in both peritrophic membrane and cuticle during morphogenesis and molting (Dixit et al., 2008). "
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    ABSTRACT: Abstract The red palm weevil (RPW; Rhynchophorus ferrugineus) is a devastating pest of palms, prevalent in the Middle East as well as many other regions of the world. Here, we report a large-scale de novo complementary DNA (cDNA) sequencing effort that acquired ∼5 million reads and assembled them into 26 765 contigs from 12 libraries made from samples of different RPW developmental stages based on the Roche/454 GS FLX platform. We annotated these contigs based on the publically available known insect genes and the Tribolium castaneum genome assembly. We find that over 80% of coding sequences (CDS) from the RPW contigs have high-identity homologs to known proteins with complete CDS. Gene expression analysis shows that the pupa and larval stages have the highest and lowest expression levels, respectively. In addition, we also identified more than 60 000 single nucleotide polymorphisms and 1 200 simple sequence repeat markers. This study provides the first large-scale cDNA dataset for RPW, a much-needed resource for future molecular studies.
    Insect Science 07/2012; 20(6). DOI:10.1111/j.1744-7917.2012.01561.x · 1.51 Impact Factor
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    • "Two previous studies have shown that the c-TuRC components Dgrip75 and Dgrip128 (as well as ctubulin 37C) are required to localise bicoid (bcd) mRNA to the anterior of the oocytes from stage 10b/11 onwards (Schnorrer et al., 2002; Vogt et al., 2006). The correct localisation of bcd mRNA is required to help pattern the anterior-posterior axis of the Drosophila embryo (Riechmann and Ephrussi, 2001), and it has been suggested that the c-TuRC nucleates a specific subset of MTs (that cannot be nucleated by the c-TuSC) that are required for proper bcd localisation. We therefore examined whether Dgp71WD was also required for the proper localisation of bcd. "
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    ABSTRACT: Dgp71WD/Nedd1 proteins are essential for mitotic spindle formation. In human cells, Nedd1 targets γ-tubulin to both centrosomes and spindles, but in other organisms the function of Dgp71WD/Nedd1 is less clear. In Drosophila cells, Dgp71WD plays a major part in targeting γ-tubulin to spindles, but not centrosomes, while in Xenopus egg extracts, Nedd1 acts as a more general microtubule (MT) organiser that can function independently of γ-tubulin. The interpretation of these studies, however, is complicated by the fact that some residual Dgp71WD/Nedd1 is likely present in the cells/extracts analysed. Here we generate a Dgp71WD null mutant lacking all but the last 12 nucleotides of coding sequence. The complete loss of Dgp71WD has no quantifiable effect on γ-tubulin or Centrosomin recruitment to the centrosome in larval brain cells. The recruitment of γ-tubulin to spindle MTs, however, is severely impaired, and spindle MT density is reduced in a manner that is indistinguishable from cells lacking Augmin or γ-TuRC function. In contrast, the absence of Dgp71WD leads to defects in the assembly of the acentrosomal female Meiosis I spindle that are more severe than those seen in Augmin or γ-TuRC mutants, indicating that Dgp71WD has additional functions that are independent of these complexes in oocytes. Moreover, the localisation of bicoid RNA during oogenesis, which requires γ-TuRC function, is unperturbed in Dgp71WD(120) mutants. Thus, Dgp71WD is not simply a general cofactor required for γ-TuRC and/or Augmin targeting, and it appears to have a crucial role independent of these complexes in the acentrosomal Meiosis I spindle.
    Biology Open 05/2012; 1(5):422-9. DOI:10.1242/bio.2012596 · 2.42 Impact Factor
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