Search results for "CLEAVAGE"
showing 10 items of 281 documents
Fibrinogen Naples I (Bβ A68T) Nonsubstrate Thrombin-Binding Capacities
2001
Fibrinogen Naples I (Bbeta A68T) is characterized by defective thrombin binding and fibrinopeptide cleavage at the fibrinogen substrate site in the E domain. We evaluated the fibrinogen of three homozygotic members of this kindred (II.1, II.2, II.3) who have displayed thrombophilic phenotypes and two heterozygotic subjects (I.1, I.2) who were asymptomatic. Electron microscopy of Naples I fibrin networks showed relatively wide fiber bundles, probably due to slowed fibrin assembly secondary to delayed fibrinopeptide release. We evaluated 125I-thrombin binding to the fibrin from subjects I.1, I.2, II.1, and II.2 by Scatchard analysis with emphasis on the high-affinity site in the D domain of f…
Detection of AA-type amyloid protein in labial salivary glands
2010
Objectives: Among the diverse forms of amyloidosis, secondary type is the most frequent one. Diagnosis of amyloid deposition is based on the identification of the fibrillary protein amyloid by means of Congo Red (CR) or crystal violet (CV) stains, but these techniques do not differentiate between the different types of amyloid fibrils. The aim of this study was to identify by immunofluorescence (IF) AA amyloid a pathological fibrillar low-molecularweight protein formed by cleavage of serum amyloid A (SAA) protein in labial salivary gland (LSG) biopsies from patients with secondary amyloidosis. Study design: 98 LSG were studied, 65 were from patients with secondary amyloidosis and 33 from su…
The polychaete Platynereis dumerilii (Annelida): a laboratory animal with spiralian cleavage, lifelong segment proliferation and a mixed benthic/pela…
2004
Platynereis dumerilii, a marine polychaetous annelid with indirect development, can be continuously bred in the laboratory. Here, we describe its spectacular reproduction and development and address a number of open research problems. Oogenesis is easily studied because the oocytes grow while floating in the coelom. Unlike the embryos of other model spiralians, the Platynereis embryo is transparent giving insight into the dynamic structures and processes inside the cells that accompany the prevailing anisotropic cleavages. Functional studies on cell specification and differential gene expression in embryos, larvae, and later stages are underway. Lifelong proliferation of uniform trunk segme…
The site of fertilisation determines dorsoventral polarity but not chirality in the zebra mussel embryo
1998
The dorsoventral polarity of unequally cleaving spiralian embryos becomes established at an early stage. The factors determining the position of the dorsoventral axis are still unknown. We present data showing that the sperm entry point (SEP) in both normal development and under experimental conditions determines the position of the first cleavage furrow in Dreissena embryos. The position of the spindles at second cleavage is directed by the site of fertilisation also, and the large, dorsal D quadrant of the 4-cell stage always forms opposite the SEP. The spiral chirality at third cleavage seems to be independent of both the fertilisation point and the arrangement of the quadrants. Dextral …
Dynamic changes of the microtubule system corresponding to the unequal and spiral cleavage modes in the embryo of the zebra mussel, Dreissena polymor…
1998
Unequal cleavage requires a highly organised cytoskeleton. We investigated the localisation of both tubulins and microtubular arrays in Dreissena eggs during and after fertilisation using confocal laser scanning microscopy. Freshly spawned eggs are arrested in metaphase I. A maternal pool of γ-tubulin is found mainly in the centre of the asters of the meiotic spindle. The paternal pool of γ-tubulin, present in the fertilising sperm, could not be traced within the egg, but a microtubule-organising centre forms near the male pronucleus at anaphase II. Male and female pronuclei grow as they migrate in the wake of their aster and rendezvous. First cleavage is unequal and starts without pronucle…
The E-modulus of the oocyte is a non-destructive measure of zona pellucida hardening
2021
Reproduction 162(4), 259-266 (2021). doi:10.1530/REP-21-0122
Biosynthesis and transformation of 20α 21-dihydroxycholesterol by rat adrenal preparations
1979
Abstract The biosynthesis of [ 3 H]-20α, 21 dihydroxycholestderol from [ 3 H]-20α-hydroxycholesterol and its transformation to [ 3 H]-21-hydroxypregnenolone by rat adrenal preparations has been demonstrated. 20α-Hydroxycholesterol was transformed to 20α, 21-dihydroxycholesterol by microsomal preparations in the presence of NADPH and 20α-21-dihydroxycholesterol was metabolized to 21-hydroxypregnenolone by mitochondrial preparations in the presence of a NADPH-generating-system. Comparison of the Michaelis-Menten-Kinetics of the steps “20α, 21-dihydroxycholesterol → 21-hydroxycholesterol” and “20α-hydroxycholesterol → pregnenolone” revealed that both compounds behaved as analogue substrates of…
Thermo-oxidative stabilization of poly(lactic acid) with antioxidant intercalated layered double hydroxides
2016
Two antioxidant modified layered double hydroxides (AO-LDHs) were successfully prepared by the intercalation of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid (IrganoxCOOH) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) in the layered structure of LDH. It was found that by anchoring the phenolic moieties to the LDH layers the antioxidant power is retained in the case of Trolox, and even amplified in the case of IrganoxCOOH. A small amount of the two AO-LDHs was incorporated into poly(lactic acid), PLA, by solution mixing and melt extrusion. The thermo-oxidative stability of the composites was compared with that of the neat PLA and PLA containing free AOs. SEC analy…
On the Establishment of Polarity in Polychaete Eggs
1990
The study of Spiralian development began about a hundred years ago when Whitman (1878) published a description of the development of the leech, Clepsine marginata. Subsequently, Spiralian development became popular because the developmental fate of each individual blastomere can be determined precisely from the cell lineage. About the turn of the century several extensive papers describing the cell lineages of various molluscs (e.g. Blochmann, 1881, 1883; Kofoid, 1895; Conklin, 1897; Wierzejski 1905) and annelids (e.g. Wilson, 1892; Mead, 1897; Woltereck, 1904) appeared. From these studies it became clear that the general principles of mollusc and annelid development (and to a much lesser d…
Quantitative analysis of cellular differentiation during early embryogenesis ofPlatynereis dumerilii.
1990
As in many spiralian embryos with unequal cleavage, cleavage inPlatynereis follows an invariant pattern. Preceding each cleavage the cytoplasm is reorganized, allowing the spiral cleavage mode to produce cells with different cytoplasmic composition. The fertilized egg undergoes a dramatic ooplasmic segregation after the completion of the cortical reaction. As a consequence, a plug of clear cytoplasm becomes located at the animal pole. Once the four quadrants of the embryo have been established, the cleavage sequence of the D quadrant differs clearly from that of the other three quadrants. The results presented here suggest that differential distribution of the clear cytoplasm governs this s…