| class aves | <ornithology, zoology> A biological class that is composed of all the birds (for example, penguins, pigeons, eagles, canaries, vultures, etc.) (09 Oct 1997) |
|---|---|
| class i | Perennial or intermittent streams that provide a source of water for domestic use. Class I streams are used by large numbers of anadromous fish or significant sports fish for spawning, rearing, or migration, or are major tributaries to other Class I streams. (05 Dec 1998) |
| class I antigens | Cell membrane bound glycoproteins that are coded by genes of the major histocompatibility complex. (05 Mar 2000) |
| class II | Perennial or intermittent streams that are used by fish for spawning, rearing, or migration. Class II streams may be tributaries to Class I streams or other Class II streams. (05 Dec 1998) |
| class II antigens | A cell membrane glycoprotein encoded by genes of the major histocompatibility complex. These antigens are distributed on antigen-presenting cells such as macrophages, B-cells, and dendritic cells. (05 Mar 2000) |
| class III | All other perennial streams not meeting higher class criteria. (05 Dec 1998) |
| class III antigens | Non-cell membrane molecules that are encoded by the S region of the major histocompatibility complex. These antigens are not involved in determining histocompatibility and include the complement proteins. (05 Mar 2000) |
| class III malocclusion | <dentistry> A Malocclusion where your lower teeth stick out past your upper teeth. This is also called an underbite. (05 Mar 2000) |
| class II malocclusion | <dentistry> A Malocclusion where your upper teeth stick out past your lower teeth. This is also called an overbite or buck teeth (05 Mar 2000) |
| class i malocclusion | <dentistry> A Malocclusion where your bite is OK (your top teeth line up with your bottom teeth) but your teeth are crooked, crowded or turned. (05 Mar 2000) |
| class iv | All other intermittent streams not meeting higher class criteria. (05 Dec 1998) |
| class switch | Change in the isotype of antibody produced after a B-cell has encountered an antigen. (05 Mar 2000) |
| cover class | A category into which plant species would fit based upon their percent areal cover, the cover classes used (midpoints in parentheses) are T = <1% cover (0), 1 = 1-5% (3.0), 2 = 6-15% (10.5), 7 = 51-75% (63.0), 6 = 76-95% (85.5), 7 = 96-100% (98.0). (09 Oct 1997) |
| histocompatibility antigens class I | Large transmembrane, polymorphic glycoproteins noncovalently associated with nonpolymorphic beta 2-microglobulin. In humans, three structural genes on chromosome 6 code for the HLA-a, HLA-b and HLA-c antigens. In mice, three genes named k, d, and l on chromosome 17 code for the h-2 antigens. Class I antigens are found on most nucleated cells and are generally detected by their reactivity with alloantisera. These antigens are recognised during graft rejection and restrict cell-mediated lysis of virus-infected cells. They are primarily associated with rheumatologic diseases and certain malignant disorders. (12 Dec 1998) |
| histocompatibility antigens class II | Large, transmembrane, non-covalently linked glycoproteins (alpha and beta). Both chains can be polymorphic although there is more structural variation in the beta chains. The class II antigens in humans are called HLA-d antigens and are coded by a gene on chromosome 6. In mice, two genes named ia and i.e. On chromosome 17 code for the h-2 antigens. The antigens are found on B-lymphocytes, macrophages, epidermal cells, and sperm and are thought to mediate the competence of and cellular cooperation in the immune response. The term ia antigens used to refer only to the proteins encoded by the ia genes in the mouse, but is now used as a generic term for any class II histocompatibility antigen. (12 Dec 1998) |