Andrew W Singson

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A high frequency of apoptosis is a conserved hallmark of oocyte development. In C. elegans, about half of all developing oocytes are normally killed by a physiological germline-specific apoptosis pathway, apparently so that they donate cytoplasm to the survivors. We have investigated the functions of CGH-1, the C. elegans ortholog of the predicted RNA(More)
The spatially restricted activities of achaete (ac) and scute (sc) are thought to define proneural clusters of potential sensory organ precursor cells in the imaginal discs of Drosophila. These genes encode transcriptional regulators of the basic helix-loop-helix (bHLH) class. We have found that direct, positive transcriptional autoregulation by the ac(More)
In Drosophila imaginal discs, the spatially restricted activities of the achaete (ac) and scute (sc) proteins, which are transcriptional activators of the basic-helix-loop-helix class, define proneural clusters (PNCs) of potential sensory organ precursor (SOP) cells. Here, we report the identification of several genes that are direct downstream targets of(More)
DYRKs are kinases that self-activate in vitro by autophosphorylation of a YTY motif in the kinase domain, but their regulation in vivo is not well understood. In C. elegans zygotes, MBK-2/DYRK phosphorylates oocyte proteins at the end of the meiotic divisions to promote the oocyte-to-embryo transition. Here we demonstrate that MBK-2 is under both positive(More)
Fertilization triggers egg activation and converts the egg into a developing embryo. The events of this egg-to-embryo transition typically include the resumption of meiosis, the reorganization of the cortical actin cytoskeleton, and the remodeling of the oocyte surface. The factors that regulate sperm-dependent egg-activation events are not well understood.(More)
Calcineurin is a Ca(2+)-calmodulin-dependent serine/threonine protein phosphatase that has been implicated in various signaling pathways. Here we report the identification and characterization of calcineurin genes in Caenorhabditis elegans (cna-1 and cnb-1), which share high homology with Drosophila and mammalian calcineurin genes. C. elegans calcineurin(More)
The molecular underpinnings of the oocyte-to-embryo transition are poorly understood. Here we show that two protein tyrosine phosphatase-like (PTPL) family proteins, EGG-4 and EGG-5, are required for key events of the oocyte-to-embryo transition in Caenorhabditis elegans. The predicted EGG-4 and EGG-5 amino acid sequences are 99% identical and their(More)
A mutation in the Caenorhabditis elegans spe-38 gene results in a sperm-specific fertility defect. spe-38 sperm are indistinguishable from wild-type sperm with regards to their morphology, motility and migratory behavior. spe-38 sperm make close contact with oocytes but fail to fertilize them. spe-38 sperm can also stimulate ovulation and engage in sperm(More)
The nematode Caenorhabditis elegans is an attractive model system for the study of fertilization. C. elegans exists as a self-fertilizing hermaphrodite or as a male. This unusual situation provides an excellent opportunity to identify and maintain sterile mutants that affect sperm and no other cells. Analysis of these mutants can identify genes that encode(More)
Fertilization in Caenorhabditis elegans requires functional SPE-9 protein in sperm. SPE-9 is a transmembrane protein with a predicted extracellular domain that contains ten epidermal growth factor (EGF)-like motifs. The presence of these EGF-like motifs suggests that SPE-9 is likely to function in gamete adhesive and/or ligand-receptor interactions. We(More)