| nuclear RNA | <molecular biology> The nucleus contains RNA that has just been synthesised, but in addition there is some that seems not to be released or is only released after further processing, the heterogenous nuclear RNA (hnRNA) and small RNA molecules associated with protein to form small nuclear ribonucleoproteins. (18 Nov 1997) |
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| nuclear run off assay | <investigation, procedure> Technique for determining which genes are being actively transcribed at a given moment in an experiment by extracting nuclear material and allowing transcription to continue, then analysing the resulting RNAs. (18 Nov 1997) |
| nuclear sap | The presumably fluid substance or gel of the nucleus in which stainable elements were believed to be suspended; much that was formerly considered to be karyolymph is now known to be euchromatin. Synonym: nuclear hyaloplasm, nuclear sap, nucleochylema, nucleochyme. Origin: karyo-+ L. Lympha, clear water (05 Mar 2000) |
| nuclear scaffold serine protease | <enzyme> Calcium-regulated serine protease which cleaves a subset of lamins a/c (intermediate filament proteins) to produce an ATP-binding protein; partial amino-terminal amino acid sequence given in first source Registry number: EC 3.4.21.- Synonym: ns protease (26 Jun 1999) |
| nuclear scan: adrenals | A nuclear scan that images the adrenal glands after a radioactive tracer is injected into the bloodstream. This test is useful in detecting a pheochromocytoma, particularly if it not within the adrenal gland. (27 Sep 1997) |
| nuclear sclerosis | Increased refractivity of the central portion of the lens of the eye. See: nuclear cataract. (05 Mar 2000) |
| nuclear spindle | See: spindle and mitosis. (18 Nov 1997) |
| nuclear stain | <technique> A stain for cell nuclei, usually based on the binding of a basic dye to DNA or nucleohistone. (05 Mar 2000) |
| nuclear transplantation | <procedure> Experimental approach in study of nucleo cytoplasmic interactions, in which a nucleus is transferred from one cell to the cytoplasm (which may be anucleate) of a second. (18 Nov 1997) |
| nuclear transport | <cell biology> Passage of molecules in and out of the nucleus, presumably via nuclear pores. Passage of proteins into the nucleus may depend on possession of a nuclear location sequence containing five consecutive positively charged residues PKKKRKV). (18 Nov 1997) |
| nuclear warfare | Warfare involving the use of nuclear weapons. (12 Dec 1998) |
| nucleolar-nuclear ratio | Ratio of volume of nucleolus to volume of nucleus, usually increased in malignant neoplasms. (05 Mar 2000) |
| direct nuclear division | <cell biology> An unusual form of nuclear division, in which the nucleus simply constricts, rather like a cell without chromosome condensation or spindle formation. Partitioning of daughter chromosomes is haphazard. Observed in some Protozoa. (18 Nov 1997) |
| indirect nuclear division | <cell biology> A method of indirect division of a cell, consisting of a complex of various processes, by means of which the two daughter nuclei normally receive identical complements of the number of chromosomes characteristic of the somatic cells of the species. Mitosis, the process by which the body grows and replaces cells, is divided into four phases. 1. Prophase: formation of paired chromosomes, disappearance of nuclear membrane, appearance of the achromatic spindle, formation of polar bodies. 2. Metaphase: arrangement of chromosomes in the equatorial plane of the central spindle to form the monaster. Chromosomes separate into exactly similar halves. 3. Anaphase: the two groups of daughter chromosomes separate and move along the fibres of the central spindle, each toward one of the asters, forming the diaster. 4. Telophase: the daughter chromosomes resolve themselves into a reticulum and the daughter nuclei are formed, the cytoplasm divides, forming two complete daughter cells. NOTE: the term mitosis is used interchangeably with cell division, but strictly speaking it refers to nuclear division, whereas cytokinesis refers to division of the cytoplasm. In some cells, as in many fungi and the fertilized eggs of many insects, nuclear division occurs within the cell unaccompanied by division of the cytoplasm and formation of daughter cells. (13 Nov 1997) |
| epstein-barr virus nuclear antigens | Nuclear antigens encoded by epstein-barr virus genes. at least six nuclear antigens have been identified but their mechanism of action and role in B-cell transformation is still unknown. (12 Dec 1998) |