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Polarization of the C. elegans zygote along the anterior-posterior axis depends on cortically enriched (PAR) and cytoplasmic (MEX-5/6) proteins, which function together to localize determinants (e.g. PIE-1) in response to a polarizing cue associated with the sperm asters. Using time-lapse microscopy and GFP fusions, we have analyzed the localization(More)
Polarization of the C. elegans zygote is initiated by ECT-2-dependent cortical flows, which mobilize the anterior PAR proteins (PAR-3, PAR-6 and PKC-3) away from the future posterior end of the embryo marked by the sperm centrosome. Here, we demonstrate the existence of a second, parallel and redundant pathway that can polarize the zygote in the absence of(More)
The metaphase to anaphase transition is a critical stage of the eukaryotic cell cycle, and, thus, it is highly regulated. Errors during this transition can lead to chromosome segregation defects and death of the organism. In genetic screens for temperature-sensitive maternal effect embryonic lethal (Mel) mutants, we have identified 32 mutants in the(More)
Homology-directed repair (HDR) of double-strand DNA breaks is a promising method for genome editing, but is thought to be less efficient than error-prone nonhomologous end joining in most cell types. We have investigated HDR of double-strand breaks induced by CRISPR-associated protein 9 (Cas9) in Caenorhabditis elegans. We find that HDR is very robust in(More)
Homology-directed repair (HDR) of breaks induced by the RNA-programmed nuclease Cas9 has become a popular method for genome editing in several organisms. Most HDR protocols rely on plasmid-based expression of Cas9 and the gene-specific guide RNAs. Here we report that direct injection of in vitro-assembled Cas9-CRISPR RNA (crRNA) trans-activating crRNA(More)
The expression of specialized signal transduction components in mammalian olfactory neurons is thought to be regulated by the O/E (Olf-1/EBF) family of transcription factors. The O/E proteins are expressed in cells of the olfactory neuronal lineage throughout development and are also expressed transiently in neurons in the developing nervous system during(More)
Asymmetric localization of PAR proteins is a hallmark of polarized cells, but the mechanisms that create PAR asymmetry are not well understood. In the C. elegans zygote, PAR asymmetry is initiated by a transient actomyosin contraction, which sweeps the PAR-3/PAR-6/PKC-3 complex toward the anterior pole of the egg. The RING finger protein PAR-2 accumulates(More)
In Caenorhabditis elegans, polarity along the anterior-posterior (A/P) axis is established shortly after fertilization and is determined by the sperm, whose position specifies the posterior end of the embryo'. Although many factors required for the establishment of A/P polarity have been described, the nature of the spatial cue provided by the sperm remains(More)
How genes are regulated to produce the correct assortment of proteins for every cell type is a fundamental question in biology. For many genes, regulation begins at the DNA level with the use of promoter sequences to control transcription. Regulation can also occur after transcription using sequences in the 3' untranslated region (UTR) of the mRNA to affect(More)
Certain cell fate decisions are specified by cell-cell interactions during the development of the nematode Caenorhabditis elegans. For example, in a wild-type hermaphrodite gonad, two cells, Z1.ppp and Z4.aaa, have the potential to become the anchor cell (AC). Intercellular communication establishes their fates and ensures that only one cell becomes the AC,(More)