Although anatomically and genetically simple, C. elegans mimics the life cycle of humans. Starting from a fertilized egg, it undergoes a complex development that gives rise to excretory, reproductive, digestive, and neuromuscular organ systems. The cell lineages of each of the 959 adult somatic cells have been directly observed, as has the fact that an additional unique set of 131 cells die during development. These deaths would have gone unnoticed, except for their demise was observable under the microscope. These observations led to the concept that apoptosis is a vital feature of development in multicellular organisms, and that it enables the shaping and carving of organs and tissues.
Today C. elegans remains one of the foremost model systems used in genetic research. Advanced descriptions have been made of its anatomy, cell lineages, developmental genetics, neural development, and reproductive cycle. The recent discovery of a mutation that doubles its life expectancy suggests that this "worm" will continue to expand its usefulness as a model system for the study of aging. Its growing significance as a member of the large, evolutionarily successful Nematoda phylum highlights the importance of C. elegans to the study of the genes involved in adaptive evolution. see also Apoptosis; Cloning Genes; Genome; Mapping; Model Organisms.
Diane C. Rein
Alberts, B., et al. Molecular Biology of the Cell, 3rd ed. New York: Garland Publishing, 1994.
Riddle, D. L., et al., eds. C. elegans II. Plainfield, NY: Cold Spring Harbor Laboratory Press, 1997.
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Born August 13, 1918, in Rendcombe, Gloucestershire, United Kingdom, Fred Sanger has been breaking new ground in chemistry for decades. In fact, he is the only person to have won a Nobel Prize in chemistry twice, and is only one of four people ever to have won a Nobel Prize more than once.
While at Cambridge University in England he developed a new method for sequencing amino acids in proteins, which he used to identify the complete sequence of insulin. For this he was awarded his first Nobel Prize in chemistry in 1958. After this success, in 1961 Sanger moved to the MRC Laboratory of Molecular Biology, where he became head of the division of protein chemistry. His colleagues' interest in nucleic acids inspired him to turn his interest in sequencing to the research of nucleic acids.
In 1977 Sanger developed a sequencing method, called the "dideoxy" method, with which he determined the entire sequence of a bacterial virus called phi-X174. This was the first time a complete sequence of a DNA molecule had been established. For this achievement he was awarded the
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