| polycloning site | Region of a phage or plasmid vector that has been engineered to contain a series of restriction sites that are usually unique within the entire vector. This makes it particularly easy to insert or excise (subclone) DNA fragments. (18 Nov 1997) |
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| Polycomb | Drosophila gene, which when mutated leads to extra sex combs on the legs of male flies, suggesting that the posterior legs have become anterior legs. There are at least 10 genes in the Polycomb group, they are thought to act by transcriptional silencing of homeotic genes. (18 Nov 1997) |
| polyconic | Pertaining to, or based upon, many cones. <geometry> Polyconic projection, a projection of the earth's surface, or any portion thereof, by which each narrow zone is projected upon a conical surface that touches the sphere along this zone, the conical surface being then unrolled. This projection differs from conic projection in that latter assumes but one cone for the whole map. Polyconic projection is that in use in the United States coast and geodetic survey. Origin: Poly- + conic. Source: Websters Dictionary (01 Mar 1998) |
| polycoria | The presence of two or more pupils in one iris. Origin: poly-+ G. Kore, pupil (05 Mar 2000) |
| polycotyledon | <botany> A plant that has many, or more than two, cotyledons in the seed. Polycotyled"onous. Origin: Poly- + cotyledon: cf. F. Polycotyledone. Source: Websters Dictionary (01 Mar 1998) |
| polycotyledonary | <anatomy> Having the villi of the placenta collected into definite patches, or cotyledons. Origin: Poly- + cotyledonary. Source: Websters Dictionary (01 Mar 1998) |
| polycrotic | <physiology> Of or pertaining to polycrotism; manifesting polycrotism; as, a polycrotic pulse; a polycrotic pulse curve. Origin: Poly- + Gr. To beat. Source: Websters Dictionary (01 Mar 1998) |
| polycrotism | <physiology> That state or condition of the pulse in which the pulse curve, or sphygmogram, shows several secondary crests or elevations; contrasted with monocrotism and dicrotism. Source: Websters Dictionary (01 Mar 1998) |
| polycyclic hydrocarbons | Hydrocarbons consisting of two or more fused ring structures. (12 Dec 1998) |
| polycyclic hydrocarbons, aromatic | <chemical> A major group of unsaturated cyclic hydrocarbons containing two or more rings. The vast number of compounds of this important group, derived chiefly from petroleum and coal tar, are rather highly reactive and chemically versatile. The name is due to the strong and not unpleasant odour characteristic of most substances of this nature. Pharmacological action: carcinogens. (12 Dec 1998) |
| polycyesis | Synonym: multiple pregnancy. Origin: poly-+ G. Kyesis, pregnancy (05 Mar 2000) |
| polycystic | Composed of many cysts. (05 Mar 2000) |
| polycystic disease of kidneys | A progressive disease characterised by formation of multiple cysts of varying size scattered diffusely throughout both kidney's, resulting in compression and destruction of kidney parenchyma, usually with hypertension, gross haematuria, and uraemia; there are two major types: 1) with onset in infancy or early childhood, usually with autosomal recessive inheritance; 2) with onset in adulthood, with autosomal dominant inheritance. Synonym: polycystic disease of kidneys. (05 Mar 2000) |
| polycystic kidney | A progressive disease characterised by formation of multiple cysts of varying size scattered diffusely throughout both kidney's, resulting in compression and destruction of kidney parenchyma, usually with hypertension, gross haematuria, and uraemia; there are two major types: 1) with onset in infancy or early childhood, usually with autosomal recessive inheritance; 2) with onset in adulthood, with autosomal dominant inheritance. Synonym: polycystic disease of kidneys. (05 Mar 2000) |
| polycystic kidney disease | <disease> A rare inherited condition in which the kidney are composed of multiple cysts. Kidney cysts are associated with an increased incidence of cerebral aneurysm. Symptoms usually appear later (if they do at all) and include blood in the urine, flank pain, excessive urination at night and abdominal pain. Individuals may also have elevated blood pressure. Chronic (end-stage renal disease) renal failure is the most common result in the 5th to 6th decades of life. Incidence: 1 in 5,000. (02 Jan 1998) |