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In metazoans, Piwi-related Argonaute proteins have been linked to germline maintenance, and to a class of germline-enriched small RNAs termed piRNAs. Here we show that an abundant class of 21 nucleotide small RNAs (21U-RNAs) are expressed in the C. elegans germline, interact with the C. elegans Piwi family member PRG-1, and depend on PRG-1 activity for(More)
RNAi-related pathways regulate diverse processes, from developmental timing to transposon silencing. Here, we show that in C. elegans the Argonaute CSR-1, the RNA-dependent RNA polymerase EGO-1, the Dicer-related helicase DRH-3, and the Tudor-domain protein EKL-1 localize to chromosomes and are required for proper chromosome segregation. In the absence of(More)
Gametogenesis is a thermosensitive process in numerous metazoans, ranging from worms to man. In Caenorhabditis elegans, a variety of RNA-binding proteins that associate with germ-line nuage (P granules), including the Piwi-clade argonaute PRG-1, have been implicated in maintaining fertility at elevated temperature. Here we describe the role of two AGO-class(More)
Chorion gene amplification in the ovaries of Drosophila melanogaster is a powerful system for the study of metazoan DNA replication in vivo. Using a combination of high-resolution confocal and deconvolution microscopy and quantitative realtime PCR, we found that initiation and elongation occur during separate developmental stages, thus permitting analysis(More)
We have studied the function of a conserved germline-specific nucleotidyltransferase protein, CDE-1, in RNAi and chromosome segregation in C. elegans. CDE-1 localizes specifically to mitotic chromosomes in embryos. This localization requires the RdRP EGO-1, which physically interacts with CDE-1, and the Argonaute protein CSR-1. We found that CDE-1 is(More)
While initial studies of small RNA-mediated gene regulatory pathways focused on the cytoplasmic functions of such pathways, identifying roles for Argonaute/small RNA pathways in modulating chromatin and organizing the genome has become a topic of intense research in recent years. Nuclear regulatory mechanisms for Argonaute/small RNA pathways appear to be(More)
In the past 20 years, the tiny soil nematode Caenorhabditis elegans has provided critical insights into our understanding of the breadth of small RNA-mediated gene regulatory activities. The first microRNA was identified in C. elegans in 1993, and the understanding that dsRNA was the driving force behind RNA-mediated gene silencing came from experiments(More)
As a champion of small RNA research for two decades, Caenorhabditis elegans has revealed the essential Argonaute CSR-1 to play key nuclear roles in modulating chromatin, chromosome segregation and germline gene expression via 22G-small RNAs. Despite CSR-1 being preserved among diverse nematodes, the conservation and divergence in function of the targets of(More)
Metazoan embryos undergo a maternal-to-zygotic transition (MZT) during which maternal gene products are eliminated and the zygotic genome becomes transcriptionally active. During this process RNA-binding proteins (RBPs) and the microRNA-induced silencing complex (miRISC) target maternal mRNAs for degradation. In Drosophila, the Smaug (SMG), Brain tumor(More)
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