| nucleic acid probe | A nucleic acid fragment, labelled by a radioisotope, biotin, etc., that is complementary to a sequence in another nucleic acid (fragment) and that will, by hydrogen binding to the latter, locate or identify it and be detected; a diagnostic technique based on the fact that every species of microbe possesses some unique nucleic acid sequences which differentiate it from all others, and thus can be used as identifying markers or "fingerprints." (05 Mar 2000) |
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| electron probe | <physics> A narrow beam of electrons used to scan or illuminate an object or screen. (05 Aug 1998) |
| electron probe microanalyser | <apparatus> The qualitative and quantitative use of X-rays excited by a microprobe of electrons. Available with scanning electron microscope and transmission electron microscope. Acronym: EMA (05 Aug 1998) |
| electron probe microanalysis | Identification and measurement of concentration of elements based on the fact that primary-emission X-rays emitted by an element excited by an electron beam have a wavelength characteristic of that element and an intensity related to its concentration. It may be performed by an electron probe microanalyzer, an electron microscope microanalyzer, or by an electron microscope, or scanning electron microscope, fitted with an X-ray spectrometer. (12 Dec 1998) |
| A-DNA | A form of DNA in which the helix is right-handed and the overall appearance is short and broad. (05 Mar 2000) |
| a-form DNA | <molecular biology> One of several forms that can be assumed by a double helix. A-DNA is stable in dehydrated conditions. This form is less common than the dominant form found under physiological conditions -- beta-DNA. This form is also assumed by DNA-RNA hybrid helices and by regions of double-stranded RNA. It is a right-handed helix and is a more compact form than beta-DNA. (09 Oct 1997) |
| antisense DNA | <molecular biology> A synthetic DNA strand that is complementary to a particular strand of target DNA with a complementary sequence of bases. This results in preventing expression of the gene encoded. These proteins can be used to selectively turn off production of certain proteins or block viral genetic instructions, by marking them for destruction by cellular enzymes, in order to prevent the building of new virus or the infection of new cells. (14 Nov 1997) |
| apurinic DNA | <molecular biology> A DNA molecule that has lost adenine and guanine, its purine bases. Apurinic DNA can be produced by treating the DNA with acid. (09 Oct 1997) |
| ATP-dependent DNA strand transferase | <enzyme> From human cell nuclei; catalyses strand exchange between homologous DNA sequences; magnesium dependent, requires ATP hydrolysis Registry number: EC 2.7.7.- Synonym: ATP-dep-DNA-str trnsfase (26 Jun 1999) |
| bacteriophage T7 induced DNA polymerase | <enzyme> Complex of two proteins, phage gene 5 protein and E coli thioredoxin Registry number: EC 2.7.7.- Synonym: t7 phage DNA polymerase, sequenase, t7 DNA polymerase, thermo sequenase (26 Jun 1999) |
| base in DNA | A unit of the DNA. There are 4 bases: adenine (A), guanine (G), thymine (T), and cytosine (C). The sequence of bases (for example, CAG) is the genetic code. (12 Dec 1998) |
| beta-DNA | <molecular biology> The normal form of DNA found in organisms, which exists as a right-handed helix. (09 Oct 1997) |
| blunt-end DNA | <molecular biology> A fragment of a DNA molecule in which the ends of both strands are even with each other rather than one strand being longer than the other. (09 Oct 1997) |
| blunt-ended DNA | Double-stranded DNA in which at least one of the ends has no unpaired bases. (05 Mar 2000) |
| vaccines, DNA | Recombinant DNA vectors encoding antigens administered for the prevention or treatment of disease. The host cells take up the DNA, express the antigen, and present it to the immune system in a manner similar to that which would occur during natural infection. This induces humoral and cellular immune responses against the encoded antigens. The vector is called naked DNA because there is no need for complex formulations or delivery agents; the plasmid is injected in saline or other buffers. (12 Dec 1998) |