(n.) A white amorphous horny substance forming the harder part of the outer integument of insects, crustacea, and various other invertebrates; entomolin.
Example Sentences:
(1) The effect of O-(carboxymethyl)chitins (CM-chitins) on the activation of mouse-peritoneal macrophages in vivo and their mitogenic activity on mouse spleen-cells were investigated.
(2) The pH activity profile, cofactor requirements, and kinetic parameters of the endogenously activated chitin synthase were identical to those of the trypsin-activated enzyme in protoplast membranes.
(3) Results obtained from isotopic dilution experiments are consistent with the operation of the chitin pathway as it has been established in fungal preparations.
(4) The significance of these results is discussed in connection with the mechanism of chitin synthesis and cell wall morphogenesis in S. cerevisiae.
(5) Here we show that the nodulation genes of this bacterium determine the production of a large family of Nod-factors which are N-acylated chitin pentamers carrying a variety of substituents.
(6) In a permeabilized-cell assay, Oct-Gln-UPOC had a 10-fold-lower inhibitory activity toward chitin synthetase than did the Oct-Lys-UPOC analog.
(7) The preparation yielded an apparent Km of 3.9 mg chitin ml-1 [17.6 mM-N-acetylglucosamine (GlcNAc) equivalents] and V of 2.3 nmol GlcNAc formed min-1 (mg protein)-1.
(8) In the case of the [14C]chitin synthesized, which does not show inhibition by alpha factor, the lowering of the specific activity of the precursor is exactly compensated for by an increased rate of chitin synthesis caused by alpha factor.
(9) Chitin derivatives are also used in things like contact lens, surgical stitches and artificial skin.
(10) The inhibitor was effective against crude or purified (chitosome) preparations of chitin synthetase.
(11) After 3 h incubation with tioconazole, 1 microgram ml-1, the incorporation of the radiolabelled glucose into chitin of intact cells and regenerating spheroplasts of C. albicans was inhibited by 43% and 30%, respectively.
(12) Electron microscopy has revealed that chitin from a representative selection of insect orders (plus one crustacean and one arachnid) is localized in crystallites about 2.8 nm across.
(13) When dividing cells of Saccharomyces cerevisiae were exposed to the polysaccharide-binding dye Congo red, the walls and septa became sites of chitin accumulation.
(14) Partially O-hydroxyethylated chitin (glycol chitin) was used as a substrate in the purification and characterization of this enzyme.
(15) In view of the small molecular size and high lipid solubility of methyl mercury and the lipophilic properties of the chitin-protein exoskeleton of the lobster, it is likely that significant uptake directly from the water as well as storage of absorbed methyl mercury occurred in the tail region.
(16) This confirmed that S. pombe cell wall is devoid of chitin.
(17) Adjuvant activity of chitin derivatives was examined in guinea-pigs and mice.
(18) DFB inhibits chitin synthesis and growth of imaginal epidermis in insects and suppresses melanogenesis and uptake of nucleosides in mouse melanoma cells, but the means of cell growth regulation and the role of metabolism of DFB in such regulation have not been established.
(19) These microfibers have a diameter of 80 A and may consist of chitin crystallites surrounded by a matrix coat.
(20) Chemical analysis of adult females of Onchocerca gibsoni gave estimated chitin contents of 200-500 micrograms (g dry weight)-1.
Chiton
Definition:
(n.) An under garment among the ancient Greeks, nearly representing the modern shirt.
(n.) One of a group of gastropod mollusks, with a shell composed of eight movable dorsal plates. See Polyplacophora.
Example Sentences:
(1) A comparison is made between the chiton myoglobins and other similar O2-binding proteins.
(2) Each of the three minerals forms a discrete microarchitectural unit of the chiton denticles.
(3) Contrary to the widely accepted view that chiton sperm lack acrosomes and that fertilization in this group occurs via a micropyle, we demonstrate here that fertilization in Tonicella lineata occurs by acrosome-mediated sperm-egg fusion.
(4) X-ray diffraction patterns show that the mature denticles of three extant chiton species are composed of the mineral lepidocrocite and an apatite mineral, probably francolite, in addition to magnetite.
(5) Although the rate constants associated with the reactions of individual dimer and monomer molecular species are very different, the two species of chiton investigated show remarkably similar properties when compared with each other.
(6) A possible circaseptennian rhythm is only suspected in the data from the ochre star (P = 0.14); it is rigorously described for the purple sea urchin (P less than 0.001) and also detected in the black chiton (P = 0.029) in time series covering 9.5 years, from September 1953 to April 1963 for the purple sea urchin and from January 1957 to September 1966 for the black chiton.
(7) The subunit structure and solution conformation of the hemocyanin of the chiton Acanthopleura granulata were investigated by light-scattering, ultracentrifugation, viscosity, absorbance, and circular dichroism methods.
(8) Cephalopod and chiton hemocyanins consist of single decameric particles, while gastropods have hemocyanins organized of di-decamers or higher assemblies.
(9) The subunit dissociation of the hemocyanins from five members of the Polyplacophora families, Acanthochitonidae, Callistoplacidae, Chitonidae, Ischnochitonidae and Mopalidae, represented by the chitons Cryptochiton stelleri, Nutallina fluxa, Acanthopleura granulata, Stenoplax conspicua and Mopalia mucosa, respectively, have been investigated by light-scattering molecular-weight and ultracentrifugation methods, using the hydrophobic reagents of the urea series and the Hofmeister salt series as probes of the contact areas of the hemocyanin subunits.
(10) Although hemocyanins have been reported in chitons, gastropods, and cephalopods, they have not been observed in the Class Bivalvia.
(11) Electron microscopy of the subradular organ of the chiton Lepidochitona cinereus (L) reveals at least three cell types, microvillous, ciliated and mucus-secreting, situated in a single epithelium.
(12) An increase and decrease in staining intensity subsequent to treatment with anti-LM4b and anti-LM2, respectively, was observed in digestive gland microsomes from BNF-treated chiton.
(13) Yoldia thraciaeformis and A. castrensis hemocyanins chromatograph on Sepharose 4B gel close to gastropod hemocyanin (Mr = 9 x 10(6] rather than chiton hemocyanin (Mr = 4 x 10(6].
(14) The shells of the chitons Lepidochitona cinereus, Sypharochiton pelliserpentis, Amaurochiton glaucus and Onithochiton neglectus were examined by scanning electron microscopy.
(15) The form of the path of attracted chiton sperm is like that observed during chemotaxis of the sperm of the hydroid Tubularia and the tunicate Ciona and resembles the behavior of Ciona sperm in that there is no increase in velocity as the cells move up the gradient.
(16) This is the first indication that lepidocrocite is precipitated by marine organisms and an apatite mineral by chitons.
(17) Observations of sperm behavior in the vicinity of gradients of egg-water or alcohol extracts of whole freshly-spawned eggs of several chitons reveal what appear to be directed movements of sperm up the gradient, resulting in the aggregation of motile sperm at the gradient source.
(18) Data series from the purple sea urchin (Strongylocentrotus purpuratus), a mollusk, the black chiton (Katharina tunicata), and the ochre sea star (Pisaster ochraceus), exhibiting circannual periods of 368, 361, and 365 days, have relatively tight 95% limits of 356-387, 356-367, and 359-371 days, respectively, when scrutinized by nonlinear least-squares rhythmometry.
(19) Newly metamorphosed chitons superficially resemble adult animals, but they lack the adult girdle ornaments, shell sculpture, and coloration.
(20) A method has been devised for isolating the calcium biomineral from the iron biominerals and organic components present in the major lateral teeth of the chiton Acanthopleura hirtosa.