| somatic cell genetics | Method for identifying the chromosomal location of a particular gene without sexual crossing. Unstable heterokaryons are made between the cell of interest and another cell with identifiably different characteristics (or without the gene in question) and a series of clones isolated. By correlating retention of gene expression with the remaining chromosomes, it is possible to deduce which chromosome must carry the gene. Human mouse heterokaryons have been extensively used in this sort of work. (18 Nov 1997) |
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| somatic cell hybridization | Production of a heterokaryon. (05 Mar 2000) |
| somatic cells | Cells of an animal or plant other than the reproductive cells. (14 Nov 1997) |
| somatic crossing-over | Crossing-over that occurs during the mitosis of somatic cells, in contrast to that which occurs in meiosis. (05 Mar 2000) |
| somatic death | Death of the entire body, as distinguished from local death. (05 Mar 2000) |
| somatic delusion | A delusion having reference to a nonexistent lesion or alteration of some organ or part of the body; sometimes indistinguishable from hypochondriasis. (05 Mar 2000) |
| somatic hybrid | Heterokaryon formed between two somatic cells, usually from different species. See: somatic cell genetics. (18 Nov 1997) |
| somatic layer | The external layer of the lateral mesoderm of the embryo, lying adjacent to the ectoderm and together with it constituting the somatopleure. (05 Mar 2000) |
| somatic mesoderm | That portion of the embryonic mesoderm that is associated with the body wall and is divided from the splanchnic visceral) mesoderm by the coelomic cavity. (18 Nov 1997) |
| somatic mitosis | The ordinary process of mitosis as it occurs in the somatic or body cells, characterised by the formation of the prescribed number of chromosomes, appropriate for the species (in humans the number is 46). (05 Mar 2000) |
| somatic mutation | Mutation that occurs in the somatic tissues of an organism and that will not, therefore, be heritable, since it is not present in the germ line. Some neoplasia is due to somatic mutation, a more conspicuous example is the reversion of some branches of variegated shrubs to the wild type (completely green) phenotype. Somatic mutation is probably also important in generating diversity in V gene regions of immunoglobulins. (18 Nov 1997) |
| somatic mutation theory of cancer | That cancer is caused by a mutation or mutations in the body cells (as opposed to germ cells), especially nonlethal mutations associated with increased proliferation of the mutant cells. (05 Mar 2000) |
| somatic nerve | <anatomy, nerve> One of the nerve's of parietal sensation or voluntary motion, as distinguished from the visceral sensory, involuntary motor and secretory nerve's. (05 Mar 2000) |
| somatic nucleus | The larger nucleus (or sometimes nuclei) in ciliate protozoans. Derived from the micronucleus by a process of DNA polytenisation. The DNA in the macronucleus is actively transcribed. The macronucleus degenerates before conjugation. (18 Nov 1997) |
| somatic recombination | One of the mechanisms used to generate diversity in antibody production is to rearrange the DNA in B-cells during their differentiation, a process that involves cutting and splicing the immunoglobulin genes. Somatic recombination via homologous crossing over occurs at a low frequency in Aspergillus, Drosphilia and Saccharomyces and in mammalian cells in culture. It may be detected through the production of homozygous patches or sectors after mitosis of cells heterozygous for suitable marker genes. (18 Nov 1997) |