| heterochromatin, facultative | Heterochromatin that need not always be heterochromatic but has the faculty to return to the normal euchromatic state. The inactive x chromosome is made up of facultatative heterochromatin. When a woman transmits that x to a son, it reverts to euchromatin and genetic activity. (12 Dec 1998) |
|---|---|
| facultative | Of parasites, optional. Compare: obligate. (09 Oct 1997) |
| facultative aerobe | <microbiology> An organism which is normally anaerobic but can also grow in the presence or oxygen. (15 Nov 1997) |
| facultative anaerobe | <microbiology> A microorganism which can survive without oxygen (is an anaerobe) but is not harmed if oxygen is present. (09 Oct 1997) |
| facultative heterochromatin | <cell biology> The heterochromatin which is condensed in some cells and not in others, presumably representing stable differences in the activity of genes in different cells. The best known example results from the random inactivation of one of the pair of X chromosomes in the cells of female mammals, (Lyonisation). (18 Nov 1997) |
| facultative hyperopia | Hyperopia that can be compensated by accommodation. Synonym: facultative hyperopia. (05 Mar 2000) |
| facultative parasite | An organism that may either lead an independent existence or live as a parasite, in contrast to obligate parasite. (05 Mar 2000) |
| facultative ponds | Ponds having an aerobic zone on the top and an anaerobic zone on the bottom. (05 Dec 1998) |
| facultative species | <ecology> Species that can occur both in wetlands and uplands, there are three subcategories of facultative species: 1. Facultative wetland plants (FACW) that usually occur in wetlands (estimated probability 67-99%), but occasionally are found in nonwetlands. 2. Facultative plants (FAC) that are equally likely to occur in wetlands or nonwetlands (estimated probability 34-66%). 3. Facultative upland plants (FACU) that usually occur in nonwetlands (estimated probability 67-99%), but occasionally are found in wetlands (estimated probability (1-33%). (09 Oct 1997) |
| ACTH suppression test | <investigation> A test that measures the response of the adrenal glands to ACTH. In this case, dexamethasone is given to the patient and then blood cortisol levels are measured. Under normal conditions, cortisol levels should drop in response to dexamethasone. In this test one milligram of dexamethasone is administered in the morning and then the blood is drawn for analysis the following morning. Abnormal test results can indicate Cushing's syndrome. (27 Sep 1997) |
| bone marrow suppression | <oncology, pharmacology> A side effect of many anticancer and antiviral drugs, including AZT. Bone marrow suppression leads to a decrease in white blood cells, red blood cells and platelets. Such reductions in turn result in anaemia, bacterial infections and spontaneous or excess bleeding. (09 Oct 1997) |
| growth hormone suppression test | <investigation> A test to determine if growth hormone is suppressed by hyperglycaemia. Growth hormone blood levels are determined sequentially after ingestion of a glucose-rich meal. If growth hormone levels remain elevated (after the glucose is given) then acromegaly or gigantism is suspected. (27 Sep 1997) |
| cortisol suppression test | <investigation> A test that measures the response of the adrenal glands to ACTH. In this case, dexamethasone is given to the patient and then blood cortisol levels are measured. Under normal conditions, cortisol levels should drop in response to dexamethasone. In this test one milligram of dexamethasone is administered in the morning and then the blood is drawn for analysis the following morning. Abnormal test results can indicate Cushing's syndrome. (27 Sep 1997) |
| nonsense suppression | Mutant tRNAs that read a chain termination codon as the signal for incorporation of a specific amino acid residue. (05 Mar 2000) |
| suppression | 1. The act of suppressing, or the state of being suppressed; repression; as, the suppression of a riot, insurrection, or tumult; the suppression of truth, of reports, of evidence, and the like. 2. <medicine> Complete stoppage of a natural secretion or excretion; as, suppression of urine; used in contradiction to retention, which signifies that the secretion or excretion is retained without expulsion. 3. Omission; as, the suppression of a word. Synonym: Overthrow, destruction, concealment, repression, detention, retention, obstruction. Origin: L. Suppressio: cf. F. Suppression. Source: Websters Dictionary (01 Mar 1998) |