| FR | failure rate; film-screen radiograph; fasciculus retroflexus; febrile reaction; feedback regulation;... |
|---|---|
| RE | radium emanation; readmission; rectal examination; reference emitter; reflux esophagitis; regional e... |
| RELP | restriction fragment length polymorphism |
| RELV | restriction fragment length variant |
| RFLP | restriction fragment length polymorphism |
| FGR | Fetal growth retardation |
|---|---|
| HB-EGF | Heparin binding epidermal growth factor-like growth factor |
| HB-EGF | Heparin-binding epidermal growth factor (EGF)-like growth factor |
| GH-IGF-I | growth hormone-insulin-like growth factor I |
| ARDRA | Amplified ribosomal DNA restriction analysis |
| restriction mapping | Use of restriction endonucleases to analyze and generate a physical map of genomes or genes. The nucleotide sequence determined is often then translated into an amino acid sequence, providing a means for sequencing the protein for which the gene codes, or for which the mRNA is a messenger. (12 Dec 1998) |
|---|---|
| restriction methylation | The enzymatic addition of methyl groups to selected adenine and cytosine residues to protect from hydrolysis by certain restriction enzymes. (05 Mar 2000) |
| restriction nuclease | <enzyme, molecular biology> Class of bacterial enzymes that cut DNA at specific sites. In bacteria their function is to destroy foreign DNA, such as that of bacteriophages (host DNA is specifically modified at these sites). Type I restriction endonucleases occur as a complex with the methylase and a polypeptide that binds to the recognition site on DNA. They are often not very specific and cut at a remote site. Type II restriction endonucleases are the classic experimental tools. They have very specific recognition and cutting sites. The recognition sites are short, 4-8 nucleotides and are usually palindromic sequences. Because both strands have the same sequence running in opposite directions the enzymes make double stranded breaks, which, if the site of cleavage is off centre, generates fragments with short single stranded tails, these can hybridise to the tails of other fragments and are called sticky ends. They are generally named according to the bacterium from which they were isolated (first letter of genus name and the first two letters of the specific name). The bacterial strain is identified next and multiple enzymes are given Roman numerals. For example the two enzymes isolated from the R strain of E. Coli are designated Eco RI and Eco RII. (10 Mar 1998) |
| restriction site | A sequence in DNA that can be recognised and cut by a specific restriction enzyme. (12 Dec 1998) |
| restriction-site polymorphism | DNA polymorphism in which the sequence of one form of the polymorphism contains a recognition site for a particular endonuclease, but the sequence of the other form lacks such a site. (05 Mar 2000) |
| MHC restriction | <immunology> Restriction on interaction between cells of the immune system because of the requirement to recognise foreign antigen is association with MHC antigens (major histocompatibility antigens). Thus, cytotoxic T-cells will only kill virally infected cells that have the same Class I antigens as themselves, whereas helper T-cells respond to foreign antigen associated with Class II antigens. (18 Nov 1997) |
| host restriction-modification | A bacterial system where the bacterium is able to destroy invading DNA from a bacteriophage (virus which infects bacteria) while at the same time preventing the destruction of their own DNA. The phage DNA is cleaved by a restriction enzyme made by the bacterium, the bacterial DNA is modified (usually with methylation) so that the enzyme will not destroy it. (09 Oct 1997) |
| DNA restriction enzymes | <enzyme> Enzymes that are part of the restriction-modification systems. They catalyze the endonucleolytic cleavage of DNA sequences which lack the species-specific methylation pattern in the host cell's DNA. Cleavage yields random or specific double-stranded fragments with terminal 5'-phosphates. The function of restriction enzymes is to destroy any foreign DNA that invades the host cell. most have been studied in bacterial systems, but a few have been found in eukaryotic organisms. They are also used as tools for the systematic dissection and mapping of chromosomes, in the determination of base sequences of dnas, and have made it possible to splice and recombine genes from one organism into the genome of another. Registry number: EC 3.1.21 (12 Dec 1998) |
| DNA restriction-modification enzymes | Systems consisting of two enzymes, a modification methylase and a restriction endonuclease. They are closely related in their specificity and protect the DNA of a given bacterial species. The methylase adds methyl groups to adenine or cytosine residues in the same target sequence that constitutes the restriction enzyme binding site. The methylation renders the target site resistant to restriction, thereby protecting DNA against cleavage. (12 Dec 1998) |
| ecori restriction enzyme | <enzyme, molecular biology> A commonly-used restriction enzyme (enzyme which will cleave the phosphodiester bonds of DNA at specific nucleotide sequences) that came from the bacteria Escherichia coli and recognises the sequence GAATTC. The enzyme will make a staggered cut of the double-stranded DNA molecule by cutting between the G and A on both strands. (09 Oct 1997) |
| lactase restriction | An inherited trait in which there is low lactase activity and thus there is defective lactose intestinal metabolism. Compare: lactase persistence. (05 Mar 2000) |
| accretionary growth | Growth by an increase of intercellular material. (05 Mar 2000) |
| appositional growth | Growth accomplished by the addition of new layers on those previously formed; e.g., the addition of lamellae in the formation of bone; it is the characteristic method of growth when rigid materials are involved. (05 Mar 2000) |
| auxetic growth | Growth by increase in the size of component cells. Synonym: intussusceptive growth. (05 Mar 2000) |
| bacterial growth | Growth of a bacterial culture either by increase in cell material or cell number. (05 Mar 2000) |