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The nematode Caenorhabditis elegans is a powerful model system to study contemporary biological problems. This system would be even more useful if we had mutations in all the genes of this multicellular metazoan. The combined efforts of the C. elegans Deletion Mutant Consortium and individuals within the worm community are moving us ever closer to this goal. At present, of the 20,377 protein-coding genes in this organism, 6764 genes with associated molecular lesions are either deletions or null mutations (WormBase WS220). Our three laboratories have contributed the majority of mutated genes, 6841 mutations in 6013 genes. The principal method we used to detect deletion mutations in the nematode utilizes polymerase chain reaction (PCR). More recently, we have used array comparative genome hybridization (aCGH) to detect deletions across the entire coding part of the genome and massively parallel short-read sequencing to identify nonsense, splicing, and missense defects in open reading frames. As deletion strains can be frozen and then thawed when needed, these strains will be an enduring community resource. Our combined molecular screening strategies have improved the overall throughput of our gene-knockout facilities and have broadened the types of mutations that we and others can identify. These multiple strategies should enable us to eventually identify a mutation in every gene in this multicellular organism. This knowledge will usher in a new age of metazoan genetics in which the contribution to any biological process can be assessed for all genes.

Articles you may be interested inAspect ratio dependence of the ideal internal kink mode stability in a toroidal plasma with circular cross section Phys.

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A mechanism for the major disruption in tokamaks is proposed involving the nonlinear destabilization of tearing modes by the m=2, n=1 tearing mode. A three-dimensional cylindrical nonlinear code based on a set of equations valid in the limit of low β and large ratio of the toroidal and poloidal magnetic fields has been constructed. The essential result is that for safety factor profiles flat in the plasma core the 2/1 mode significantly destabilizes other modes, particularly odd modes such as the 3/2 mode, before the 2/1 island in the single-pitch limit has expanded to its maximum width. Many magnetic islands of different pitch are produced and the corresponding deformation of the toroidal current density is more severe than in the two-dimensional case. The magnetic islands generated can extend across the plasma cross section; presumably, the corresponding ergodic magnetic fields can result in the escape of particles and heat from the plasma core. An analytic model in agreement with these results is also presented.