| allantoinuria | The urinary excretion of allantoin; normal in most mammals, abnormal in humans. Origin: allantoin + G. Ouron, urine (05 Mar 2000) |
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| allantois | An embryonic diverticulum of the hindgut of reptiles, birds, and mammals; in man its blood vessels give rise to those of the umbilical cord. (12 Dec 1998) |
| allatostatin | <hormone> Peptide hormones produced by the corpora allata of insects that reversibly inhibit the production of juvenile hormone. Similar peptides are found in other Phyla. Allatostatin 4, smallest of the family, is DRLYSFGL amide. Allatostatins may also be produced in other insect tissues, particularly mid gut. (18 Nov 1997) |
| allaxis | Synonym: metamorphosis. Origin: G. Allattein, to alter (05 Mar 2000) |
| allegiance | 1. The tie or obligation, implied or expressed, which a subject owes to his sovereign or government; the duty of fidelity to one's king, government, or state. 2. Devotion; loyalty; as, allegiance to science. Synonym: Loyalty, fealty. Allegiance, Loyalty. These words agree in expressing the general idea of fidelity and attachment to the "powers that be." Allegiance is an obligation to a ruling power. Loyalty is a feeling or sentiment towards such power. Allegiance may exist under any form of government, and, in a republic, we generally speak of allegiance to the government, to the state, etc. In well conducted monarchies, loyalty is a warm-hearted feeling of fidelity and obedience to the sovereign. It is personal in its nature; and hence we speak of the loyalty of a wife to her husband, not of her allegiance. In cases where we personify, loyalty is more commonly the word used; as, loyalty to the constitution; loyalty to the cause of virtue; loyalty to truth and religion, etc. "Hear me, recreant, on thine allegiance hear me!" (Shak) "So spake the Seraph Abdiel, faithful found, . . . Unshaken, unseduced, unterrified, His loyalty he kept, his love, his zeal." (Milton) Origin: OE. Alegeaunce; pref. A- + OF. Lige, liege. The meaning was influenced by L. Ligare to bind, and even by lex, legis, law. See Liege, Ligeance. Source: Websters Dictionary (01 Mar 1998) |
| allele | <genetics> Any one of a series of two or more different genes that occupy the same position (locus) on a chromosome. Since autosomal chromosomes are paired, each autosomal locus is represented twice. If both chromosomes have the same allele, occupying the same locus, the condition is referred to as homozygous for this allele. If the alleles at the two loci are different, the individual or cell is referred to as heterozygous for both alleles. (15 Nov 1997) |
| alleles | Mutually exclusive forms of the same gene, occupying the same locus on homologous chromosomes, and governing the same biochemical and developmental process. (12 Dec 1998) |
| allelic | Relating to an allele. Synonym: allelomorphic. (05 Mar 2000) |
| allelic exclusion | <cell biology, genetics> The process whereby one or more loci on one of the chromosome sets in a diploid cell is inactivated (or destroyed) so that the locus or loci is (are) not expressed in that cell or a clone founded by it. For example in mammals one of the X chromosome pairs of females is inactivated early in development (see Lyon hypothesis) so that individual cells express only one allelic form of the product of that locus. Since the choice of chromosome to be inactivated is random, different cells express one or other of the X chromosome products resulting in mosaicism. The process is also known to occur in immunoglobulin genes so that a clone expresses only one of the two possible allelic forms of immunoglobulin. (19 Dec 1998) |
| allelic gene | See: allele, dominance of traits. (05 Mar 2000) |
| allelism | The state held in common by alleles. Synonym: allelomorphism. (05 Mar 2000) |
| allelocatalysis | Self-stimulation of growth in a bacterial culture by addition of similar cells. Origin: G. Allelon, mutually, reciprocally, + catalytikos, able to dissolve (05 Mar 2000) |
| allelocatalytic | Mutually catalytic; denoting two substances each of which is decomposed in the presence of the other. (05 Mar 2000) |
| allelochemical | <cell biology> Substances effecting allelopathic reactions. See: allelopathy. (18 Nov 1997) |
| allelochemicals | Signal substances between individuals of different species. Compare: pheromones. Origin: G. Allelon, reciprocally, + chemical (05 Mar 2000) |