| LCSS | lethal congenital contracture syndrome |
|---|---|
| LD | labor and delivery; laboratory data; labyrinthine defect; lactate dehydrogenase; laser Doppler; lear... |
| LD50 | median lethal dose |
| LD50/30 | a dose that is lethal for 50% of test subjects within 30 days |
| LD100 | lethal dose in all exposed subjects |
| up mutation | <molecular biology> Refers to any mutation in the promoter region of a gene which can trigger transcription initiation. (09 Oct 1997) |
|---|---|
| up promoter mutation | A mutation that increases the frequency of initiation of transcription. (05 Mar 2000) |
| forward mutation | Any mutation which renders a formerly functional gene nonfunctional. Compare: back mutation. (09 Oct 1997) |
| 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) |