(n.) One of the Diatomaceae, a family of minute unicellular Algae having a siliceous covering of great delicacy, each individual multiplying by spontaneous division. By some authors diatoms are called Bacillariae, but this word is not in general use.
(n.) A particle or atom endowed with the vital principle.
Example Sentences:
(1) The cytoplasmic and chloroplast ribosomes from the marine diatom Cylindrotheca fusiformis were isolated and characterized.
(2) The concentration of acetate in the interstitial water fell from about 100 microM (immediately after sedimentation of the spring diatom bloom) to a relatively constant value of about 20 microM in late summer, during which acetate utilization appeared to be balanced by production.
(3) The affinity of the diatom for glucose was greater than that shown by the bacterium, but the Km for glucose transport, 1.5x10-5M was too high to allow effective removal of glucose at in situ concentrations.
(4) We have cloned and sequenced a 5200 base restriction fragment and an overlapping 3100 base fragment of the large single copy region of the chloroplast genome of the diatom Odontella sinensis, which hybridized to several ATPase gene probes.
(5) The material consisted of 285 successive drownings, which were subject to autopsy at the Helsinki University Department of Forensic Medicine between 1978 and 1986 and for whom diatom analysis was carried out.
(6) Substituting size-fractionated silica particles for diatoms (the fossilized cell walls of unicellular algae) allowed for the purification of microgram amounts of genomic DNA, plasmid DNA, and rRNA from cell-rich sources, as exemplified for pathogenic gram-negative bacteria.
(7) In diatom and yeast spindles, elongation of the spindle in anaphase (anaphase B) may be explained by microtubule assembly at polar microtubule ends in the spindle mid-zone and sliding of the antiparallel microtubules from the opposite poles.
(8) Cells of the diatom Cyclotella meneghiniana were exposed in a closed system to 0.245 ppm 1,2,3-trichlorobenzene.
(9) Cells of the diatom Cyclotella meneghiniana were exposed in a closed system to 0.245 ppm 1,3,5-trichlorobenzene.
(10) Extracted diatom DNA separates into two bands in CsCl-Hoechst 33258 dye gradients.
(11) Quinones constituting the electron transfer systems in a marine unicellular diatom, Phaeodactylum tricornutum, were isolated and identified chromatographically.
(12) A new sulfonolipid has been isolated from a non-photosynthetic diatom, Nitzschia alba, by thin-layer and column chromatography on silicic acid, and characterized by 35S-labeling, mobility on thin-layer chromatography, infrared and NMR spectroscopy and products of hydrolysis, as a ceramide sulfonic acid (N-acyl sphingosine-1-sulfonic acid).
(13) Among eukaryotes, red algae emerged first; and, later, thraustochytrids (a Proctista group), ascomycetes (yeast), green plants (green algae and land plants), "yellow algae" (brown algae, diatoms, and chrysophyte algae), basidiomycetes (mushrooms and rusts), slime- and water molds, various protozoans, and animals emerged, approximately in that order.
(14) The spindle of the colonial diatom Fragilaria contains two distinct sets of spindle microtubules (MTs): (a) MTs comprising the central spindle, which is composed of two half-spindles interdigitated to form a region of "overlap"; (b) MTs which radiate laterally from the poles.
(15) The conformation of berchemolide was calculated by MNDO (modified neglect of diatomic overlap).
(16) Usually algal populations change from a dominance of diatoms and green algae to dominance by blue-green algae.
(17) But it seems to have stuck.” The following year, Crutzen and Eugene Stoermer – an American diatom specialist who had been using the term informally since the 1980s – jointly published an article proposing that the Anthropocene should be considered a new Earth epoch, on the grounds that “mankind will remain a major geological force for many millennia, maybe millions of years to come”.
(18) The particles are surfaces for the attachment of diatoms and hydroids.
(19) Mitotic spindles isolated from the diatom Stephanopyxis turris consist of two half-spindles of closely interdigitating microtubules that slide relative to one another in the presence of ATP, reinitiating spindle elongation (anaphase B) in vitro.
(20) We describe here a simple procedure for isolating diatom spindles which are capable of anaphase spindle elongation in vitro.
Theca
Definition:
(n.) A sheath; a case; as, the theca, or cell, of an anther; the theca, or spore case, of a fungus; the theca of the spinal cord.
(n.) The chitinous cup which protects the hydranths of certain hydroids.
(n.) The more or less cuplike calicle of a coral.
(n.) The wall forming a calicle of a coral.
Example Sentences:
(1) By 24 hr, rough endoplasmic reticulum in thecal cells increased from 4.2 to 7% of cell volume, while the amount in granulosa cells increased from less than 3.5% to more than 10%; the quantity remained relatively constant in the theca but declined to prestimulation values in the granulosa layer.
(2) In the small ovarian follicles, the immunostaining for TGF-beta 1 was present in oocytes, follicle cells, and granulosa and theca cell layers.
(3) These results suggest that TGF-alpha is synthesized in the ovary, perhaps in the theca-interstitial compartment.
(4) 125I-Labelled OTA consistently labelled the ovarian stroma and the theca interna, but not the corpora lutea, the granulosa cells or the theca externa.
(5) This leads, in turn, to triple-layering of the theca interna in follicles of the 2nd resting period.
(6) The electron microscopy examinations showed that a large amount of collagen fibers scattered under the albuginea layer and interwove with cells of albuginea and theca externa.
(7) The binding sites for human follicle-stimulating hormone were found in three tumors of epithelial origin (serous cystadenoma and mucinous cystadenoma) and in two of sex cord-stromal origin (theca cell tumor and theca-granulosa cell tumor).
(8) The purpose of this study was to compare the steroidogenic potential of the granulosa, theca, and medullary tissues from polycystic and normal ovaries.
(9) Those cells such as the granulosa cells of smaller follicles, the theca interna cells, the interstitial gland cells, oocytes, peritoneal epithelial cells were entirely negative.
(10) A significant increase in thymidine per follicle occurred at 15:00 h on Days 1 and 3 of the cycle from stage 2 (bilaminar follicle) to stage 6 (7-8 layers granulosa cells plus theca).
(11) Taken together, these and previous observations reveal fundamental differences in the cellular localization and hormonal regulation of ovarian IGF gene expression in that IGF-II gene expression (unlike IGF-I) is theca-interstitial (rather than granulosa) cell-specific, and is subject to down (as opposed to up) regulation in response to estrogenic stimulation.
(12) Marked infolding of both the granulosa and theca tissue in some follicles suggested early luteinization.
(13) Cellular localization studies revealed the IGFBP-3 gene to be exclusively expressed in the theca-interstitial rather than the granulosa cell compartment.
(14) The acquisition of catecholamine responsiveness was specific to hCG; if theca-interstitial cells were induced to differentiate with either prostaglandin E2 or cholera toxin, then isoproterenol did not enhance androgen synthesis.
(15) CR was primarily localized in interstitial gland cells and in theca interna cells but was not found in corpora lutea cells in the ovary during the estrous cycle.
(16) Specific LH receptors with common binding properties were detected in both granulosa and theca layers of large preovulatory follicles.
(17) The rat perforatorium is the part of the perinuclear theca that underlies the acrosomic system.
(18) One to several layers of theca interna cells just beneath membrana granulosa did not demonstrate any immunoreactivity of 3 beta-HSD or that of cytochrome P-450 17 alpha-hydroxylase.
(19) To test the possibility that progesterone released by granulosa cells may serve as a substrate for production of androgen in theca cells, specific antiserum was used to adsorb progesterone present in the medium.
(20) Very few adrenergic nerve fibres were present in the theca interna of follicles or in the corpus luteum.