| leptosporangiate | <plant biology> Of ferns, having sporangia with walls only one cell thick. Compare: eusporangiate. (09 Oct 1997) |
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| leptostraca | <zoology> An order of Crustacea, including Nebalia and allied forms. Origin: NL, fr. Gr. Thin, slender + shell of a testacean. Source: Websters Dictionary (01 Mar 1998) |
| leptotene | <cell biology, genetics> Classical term for the first stage of prophase I of meiosis, during which the chromosomes condense and become visible. (18 Nov 1997) |
| leptothricosis | An obsolete term for any disease caused by the now invalid genus Leptothrix. (05 Mar 2000) |
| leptothrix | <biology> A genus of bacteria, characterised by having their filaments very long, slender, and indistinctly articulated. Origin: NL, fr. Gr. Small + hair. <biology> Having the form of a little chain; applied to bacteria when, as in multiplication by fission, they form chain of filiform individuals. See: Leptothrix. Source: Websters Dictionary (01 Mar 1998) |
| Leptotrichia | A genus of anaerobic, nonmotile bacteria containing Gram-negative, straight or slightly curved rods, 5 to 15 um in length, with one or both ends rounded, often pointed. Granules are distributed evenly along the long axis, and one or more large granules may localise near the end of the cell. Branched or clubbed forms do not occur. Two or more cells join together and form septate filaments of varying length; in older cultures, filaments up to 200 um may form and twist around each other; large, coccoid bodies may be found within a filament as a cell lyses. Carbon dioxide is essential for optimal growth. Lactic acid is produced from glucose. These organisms occur in the oral cavity of humans. The type species is Leptotrichia buccalis. Origin: Lepto-+ G. Thrix, hair Leptotrichia buccalis, a species found in the human mouth; it is the type species of the genus Leptotrichia. (05 Mar 2000) |
| Leptotrombidium | An important genus of trombiculid mites, formerly considered a subgenus of the genus Trombicula, which includes all of the vectors of scrub typhus (tsutsugamushi disease). Members of Leptotrombidium that serve as vectors of scrub typhus are within the Leptotrombidium deliense group: Leptotrombidium akamushi is the classical vector in Japan; Leptotrombidium deliense is the primary vector, extending from New Guinea, Australia, the Philippines, China, and Southeast Asia to western Pakistan; Leptotrombidium fletcheri is found in Malaysia, New Guinea, and the Philippines. Some eight other species have also been implicated in scrub typhus transmission in more limited areas. Leptotrombidium akamushi, one of two species, the other being Leptotrombidium deliensis (T. Deliensis), implicated in the transmission of Rickettsia tsutsugamushi, agent of tsutsugamushi disease in Japan and elsewhere in the Orient; the larvae of these species are characteristic parasites of rodents, which therefore are reservoirs of human infections, although the mites themselves are also reservoirs, as their rickettsial parasites are transovarially transmitted from generation to generation (a requirement for transmission to humans as only larval mites feed parasitically and then only once in their lifetimes). Synonym: Trombicula akamushi. (05 Mar 2000) |
| leptus | <zoology> The six-legged young, or larva, of certain mites; sometimes used as a generic name. See Harvest mite, under Harvest. Origin: NL, from Gr. Thin, small. Source: Websters Dictionary (01 Mar 1998) |
| leptynite | <chemical> See Granulite. Source: Websters Dictionary (01 Mar 1998) |