| H/S | helper-suppressor [ratio] |
|---|---|
| NSC | neurosecretory cell; no significant change; nonservice connected; nonspecific suppressor cell; norma... |
| SAD | Scale of Anxiety and Depression; seasonal affective disorder; Self-Assessment Depression [scale]; se... |
| SAI | Self-Analysis Inventory; Sexual Arousability Inventory; Social Adequacy Index; suppressor of anchora... |
| SCA | self-care agency; severe congenital anomaly; sickle-cell anemia; single-camera autostereoscopic [ima... |
| T-lymphocytes, suppressor-inducer | Subpopulation of CD4+ lymphocytes which induce CD8+ suppressor T-cells (T-lymphocytes, suppressor-effector) to suppress antibody production by B-cells. They also stimulate other cellular immune responses. (12 Dec 1998) |
|---|---|
| T suppressor cell | <haematology, immunology> Set of T lymphocytes (usually CD8) specifically involved in suppressing B-cell differentiation into antibody secreting cells. There may also be T suppresors of T-cell functions. (18 Nov 1997) |
| t-suppressor cell | A type of immune cells, also called t8 cells, these cells close down the immune response after it has destroyed invading organisms. T8 cells are sensitive to high concentrations of circulating lymphokine hormones and release their own lymphokines after an immune response has achieved its goal, signalling all other participants to cease their attack. Some memory B-cells remain to ward off a repeat attack by the invading organism. (12 Dec 1998) |
| tumour suppressor | <molecular biology, oncology> A gene that encodes a product that normally negatively regulates the cell cycle and that must be mutated or otherwise inactivated before a cell can proceed to rapid division. Examples: p53, RB retinoblastoma), WT 1 (Wilm's tumour), DCC (deleted in colonic carcinoma), NF 1 (neurofibrosarcoma) and APC adenomatous polyposis coli). (18 Nov 1997) |
| acquired mutation | A change in a gene or chromosome that occurs in a single cell after the conception of the individual. That change is then passed along to all cells descended from that cell. Acquired mutations are involved in the development of cancer. (12 Dec 1998) |
| addition-deletion mutation | <molecular biology> A type of mutation that results from insertion or deletion of a single nucleotide into, or from, an open reading frame in the normal DNA sequence. Normally, the genetic code is read in the wrong frame, three nucleotides at a time, and the entire sequence downstream of the mutation, is translated into a polypeptide with a garbled amino acid sequence from the mutated codon onwards. These mutations may be induced by certain types of mutagens or may occur spontaneously and usually result in the generation, downstream, of nonsense, chain termination codons. Synonym: addition mutation, addition-deletion mutation, deletion mutation, reading-frameshift mutation. (21 Jun 2000) |
| addition mutation | <molecular biology> A type of mutation that results from insertion or deletion of a single nucleotide into, or from, an open reading frame in the normal DNA sequence. Normally, the genetic code is read in the wrong frame, three nucleotides at a time, and the entire sequence downstream of the mutation, is translated into a polypeptide with a garbled amino acid sequence from the mutated codon onwards. These mutations may be induced by certain types of mutagens or may occur spontaneously and usually result in the generation, downstream, of nonsense, chain termination codons. Synonym: addition mutation, addition-deletion mutation, deletion mutation, reading-frameshift mutation. (21 Jun 2000) |
| amber mutation | <molecular biology> A mutation from a codon which codes for an amino acid into the amber codon UAG, which normally signals that the translation of mRNA into an amino acid chain should stop. The mutation causes the amino acid chain to stop forming before it is actually completed. (09 Oct 1997) |
| back mutation | <molecular biology> A mutation that causes a mutant gene to revert to its original wild-type base sequence. Compare: forward mutation. (09 Oct 1997) |
| reading-frameshift mutation | <molecular biology> A type of mutation that results from insertion or deletion of a single nucleotide into, or from, an open reading frame in the normal DNA sequence. Normally, the genetic code is read in the wrong frame, three nucleotides at a time, and the entire sequence downstream of the mutation, is translated into a polypeptide with a garbled amino acid sequence from the mutated codon onwards. These mutations may be induced by certain types of mutagens or may occur spontaneously and usually result in the generation, downstream, of nonsense, chain termination codons. Synonym: addition mutation, addition-deletion mutation, deletion mutation, reading-frameshift mutation. (21 Jun 2000) |
| germinal mutation | A mutation in the germ cells (the cells which will undergo meiosis to form the gametes). Such mutations are therefore passed on to offspring. (09 Oct 1997) |
| germ-line mutation | Any detectable and heritable alteration in the lineage of germ cells. Mutations in these cells (i.e., "generative" cells ancestral to the gametes) are transmitted to progeny while those in somatic cells are not. (12 Dec 1998) |
| reverse mutation | <molecular biology> A mutation that causes a mutant gene to revert to its original wild-type base sequence. Compare: forward mutation. (09 Oct 1997) |
| chromosomal mutation | Can refer to any of a number of DNA mutations which results in a change in the protein encoded by the mutated gene, such as point mutations, insertion or deletion mutations (frameshift mutations), or nonsense mutations. More often this refers to mutations involving chromosomes, such as the inversion of part of one chromosome such that the inverted part no longer matches with its homologous pair, a translocation of one part of a chromosome to a different chromosome, deletions of parts of chromosomes, or accidents which happen during the division of the nucleus like the unequal portioning of chromosomes between the daughter cells. (09 Oct 1997) |
| missense mutation | <molecular biology> A mutation that alters a codon for a particular amino acid to one specifying a different amino acid. (18 Nov 1997) |