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[
Science,
1998]
The near completion of the sequence of the C. elegans genome should provide researchers with a gold mine of information on topics ranging from evolution to gene
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[
Curr Biol,
2014]
The handover from maternal to zygotic control has to be carefully orchestrated. In most animal embryos, maternal products drive early embryogenesis, and the genome of the zygote is only switched on later. However, in the nematode Ascaris the zygotic genome is never silent, and the maternal products are rapidly eliminated.
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[
Science,
2001]
Animals have evolved a plethora of elaborate mechanisms to ensure successful sexual reproduction. These run the gamut from intricate mating rituals and release of pheromones, which aid in the identification of appropriate partners, to cell-cell signaling events that coordinate the timing of meiosis (cell division of egg and sperm precursors), gamete formation, and fertilization. The nematode Caenorhabditis elegans, an unrepentant minimalist of the animal kingdom, maximizes the efficiency of its reproductive resources several ways.
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[
Nature,
1998]
The human genome is predicted to contain between 50,000 and 100,000 genes. To work out what these genes do, an array of techniques is needed to evaluate the protein-protein interactions and biochemical pathways of any gene product. The nematode worm Caenorhabditis elegans is an excellent system for such studies because of its well-understood genetics and development, evolutionary conservation to human genes, small genome size and relatively short life cycle. The 100-megabase-pair genome will be completely sequenced this year, and a total of 17,000 genes have been predicted, many with human counterparts. Approaches used to manipulate gene expression in C. elegans include transposon-mediated deletion, antisense inhibition and direct isolation of deletions after mutagenesis. Although these methods have proved useful, limitations still exist.
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[
Dev Cell,
2013]
Molecular insights into the genetic control of development have been mainly derived from single gene mutant studies. Francesconi and Lehner (2013) report now in Nature a genome-wide map of natural sequence variants that affect the temporal expression dynamics of thousands of genes during development of the roundworm Caenorhabditis elegans.
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Dev Cell,
2015]
In this issue of Developmental Cell, Elewa etal. (2015) show that combinatorial action of RNA binding proteins modulates poly(A) tail length of maternal mRNAs, leading to asymmetric expression of a cell fate determinant in early C.elegans embryos. Genome-wide profiling suggests this mechanism may be widely used to establish cell identities.
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[
Nat Genet,
2012]
A new study reports a comprehensive survey of genetic diversity in natural populations of the nematode Caenorhabditis elegans. Their analyses suggest that recent chromosome-scale selective sweeps have reduced C. elegans genetic diversity worldwide and strongly structured genetic variation across its genome.
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[
Dev Cell,
2014]
Epigenetic memory stably maintains and transmits information during genome replication. Recently in Science, Gaydos etal. (2014) show that repressive chromatin marks exhibit transgenerational stability in the absence of chromatin-modifying enzymes in Caenorhabditis elegans, in contrast to work in flies suggesting that such proteins mediate stable inheritance of epigenetic modifications.
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[
Genetics,
2013]
With remarkable speed, the CRISPR-Cas9 nuclease has become the genome-editing tool of choice for essentially all genetically tractable organisms. Targeting specific DNA sequences is conceptually simple because the Cas9 nuclease can be guided by a single, short RNA (sgRNA) to introduce double-strand DNA breaks (DSBs) at precise locations. Here I contrast and highlight protocols recently developed by eight different research groups, six of which are published in GENETICS, to modify the Caenorhabditis elegans genome using CRISPR/Cas9. This reverse engineering tool levels the playing field for experimental geneticists.
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[
Nature,
1992]
Supporters of large DNA sequencing projects will take heart (and find much to learn) from the report by J. Sulston and colleagues that appears on page 37 of this issue. Sulston et al. describe the first results of the Caenorhabditis elegans genome sequencing project, and have come up with not only hitherto unknown genes but also with fresh and biologically relevant information.