scholarly journals Underhydroxylated minor cartilage collagen precursors cannot form stable triple helices

1988 ◽  
Vol 250 (1) ◽  
pp. 65-70 ◽  
Author(s):  
C C Clark ◽  
C F Richards
Keyword(s):  
Chick Embryo ◽  
Triple Helix ◽  
Iron Chelator ◽  
Prolyl Hydroxylase ◽  
Type Ii ◽  
Native Structure ◽  
Lysyl Hydroxylase ◽  
Free Cells ◽  
Triple Helices ◽  
Matrix Free

Matrix-free cells from chick-embryo sterna were incubated with various concentrations of 2,2′-bipyridyl, an iron chelator that inhibits prolyl hydroxylase and lysyl hydroxylase. At concentrations in the region of 0.1 mM, significant effects on cartilage collagen hydroxylation and secretion were observed. When the underhydroxylated collagens were subsequently digested with chymotrypsin or chymotrypsin plus trypsin at 4 degrees C for 15 min, the minor cartilage collagen precursors (namely types IX and XI) were extensively degraded; type II procollagen was only partially susceptible and was converted into underhydroxylated collagen. The results demonstrate that there were significant differences in triple-helix stability among cartilage collagens such that the underhydroxylated minor collagen precursors were unable to attain a native structure under conditions where type II procollagen was successful.

scholarly journals Effect of cortisol acetate on collagen biosynthesis and on the activities of prolyl hydroxylase, lysyl hydroxylase, collagen galactosyltransferase and collagen glucosyltransferase in chick-embryo tendon cells

1977 ◽  
Vol 164 (3) ◽  
pp. 533-539 ◽  
Author(s):  
A Oikarinen
Keyword(s):  
Chick Embryo ◽  
Enzyme Activities ◽  
Collagen Synthesis ◽  
Enzyme Synthesis ◽  
Prolyl Hydroxylase ◽  
Chick Embryos ◽  
Isolated Cells ◽  
Lysyl Hydroxylase ◽  
Tendon Cells

Collagen synthesis and the activities of prolyl hydroxylase, lysyl hydroxylase, collagen galactosyltransferase and collagen glucosyltransferase were studied in isolated chick-embryo tendon cells after the administration of cortisol acetate to the chick embryos. When the steroid was injected 1 day before isolation of the tendon cells, collagen synthesis was decreased, even though the enzyme activities were not changed. When cortisol acetate was given as repeated injections over a period of 4 days, both collagen synthesis and the enzyme activities decreased. The hydroxylase activities decreased even more than the two collagen glycosyltransferase activities, both in isolated cells and in whole chick embryos. The amount of prolyl hydroxylase protein diminished to the same extent as the enzyme activity, indicating that cortisol acetate inhibits enzyme synthesis. The inhibitory effect of cortisol acetate on collagen synthesis and on the enzyme activities was partially reversible in 3 days. Total protein synthesis was completely restored within this time. Only massive doses of cortisol acetate inhibited collagen synthesis in vitro. Additional experiments indicated that cortisol acetate did not decrease the rate of the enzyme reactions when added directly to the enzyme incubation mixtures. The results suggest that cortisol acetate decreases collagen synthesis both by its direct effect on collagen polypeptide-chain synthesis and by decreasing the activities of enzymes involved in post-translational modifications.

scholarly journals Nitric oxide inhibits the synthesis of type-II collagen without altering Col2A1 mRNA abundance: prolyl hydroxylase as a possible target

1997 ◽  
Vol 324 (1) ◽  
pp. 305-310 ◽  
Author(s):  
M. CAO ◽  
A. WESTERHAUSEN-LARSON ◽  
C. NIYIBIZI ◽  
K. KAVALKOVICH ◽  
H. I. GEORGESCU ◽  
...  
Keyword(s):  
Collagen Synthesis ◽  
Articular Chondrocytes ◽  
Type Ii Collagen ◽  
Suppressive Effect ◽  
Prolyl Hydroxylase ◽  
Type Ii ◽  
Independent Manner ◽  
No Donor ◽  
Triple Helices ◽  
Important Enzyme

The addition of human recombinant interleukin-1β (IL-1β) to cultures of lapine articular chondrocytes provoked the synthesis of large amounts of NO and reduced the production of type-II collagen. NG-Monomethyl-l-arginine (L-NMA), an inhibitor of NO synthase, strongly suppressed the production of NO and partially relieved the inhibition of collagen synthesis in response to IL-1β. The NO donor S-nitrosoacetylpenicillamine (SNAP), on the other hand, inhibited collagen production. IL-1 lowered the abundance of Col2A1 mRNA in an NO-independent manner. Collectively, these data indicate that IL-1 suppresses collagen synthesis at two levels: a pretranslational level which is NO-independent, and a translational or post-translational level which is NO-mediated. These effects are presumably specific as L-NMA and SNAP had no effect on total protein synthesis or on the distribution of newly synthesized proteins between the cellular and extracellular compartments. Prolyl hydroxylase is an important enzyme in the post-translational processing of collagen, and its regulation and cofactor requirements suggest possible sensitivity to NO. Extracts of cells treated with IL-1 or SNAP had lower prolyl hydroxylase activity, and L-NMA was partially able to reverse the effects of IL-1. These data suggest that prolyl hydroxylase might indeed be a target for NO. Because underhydroxylated collagen monomers fail to anneal into stable triple helices, they are degraded intracellularly. Inhibition of prolyl hydroxylase by NO might thus account for the suppressive effect of this radical on collagen synthesis.

scholarly journals Catalytic properties of lysyl hydroxylase from cells synthesizing genetically different collagen types

1982 ◽  
Vol 201 (1) ◽  
pp. 215-219 ◽  
Author(s):  
U Puistola
Keyword(s):  
Chick Embryo ◽  
Type I Collagen ◽  
Type Ii Collagen ◽  
Type I ◽  
Type Ii ◽  
Collagen Types ◽  
Enzyme Preparations ◽  
Lysyl Hydroxylase ◽  
Type Iv ◽  
Sarcoma Cells

Crude preparations of lysyl hydroxylase were extracted from chick-embryo tendons synthesizing exclusively type I collagen, chick-embryo sterna synthesizing exclusively type II collagen and HT-1080 sarcoma cells synthesizing exclusively type IV collagen. No differences were found in the Km values for Fe2+, 2-oxoglutarate and ascorbate between these three enzymes preparations. Similarly no differences were found in the Km values for type I and type II protocollagens and the rate at which type IV protocollagen is hydroxylated between these enzyme preparations. The extent to which type I protocollagen could be hydroxylated by the three enzymes was likewise identical. These data strongly argue against the existence of collagen-type-specific lysyl hydroxylase isoenzymes.

scholarly journals Cryo-ET analysis of budding yeast synaptonemal complexes in situ

2019 ◽  
Author(s):  
Olivia X. Ma ◽  
Shujun Cai ◽  
Jian Shi ◽  
Lu Gan
Keyword(s):  
Triple Helix ◽  
Phase Contrast ◽  
Central Element ◽  
Super Resolution ◽  
Native Structure ◽  
Homologous Chromosomes ◽  
Triple Helices ◽  
Subtomogram Averaging ◽  
Electron Cryotomography

ABSTRACTThe synaptonemal complex (SC) is the large, conserved, proteinaceous scaffold that assembles between and holds together homologous chromosomes in meiotic prophase. Knowledge of the native structure of this complex is needed to evaluate how the SC carries out its functions. Traditional electron microscopy and super-resolution light microscopy have revealed that in many organisms, the SC has a ladder-like structure: two rail-like lateral elements are bridged by a set of rung-like transverse filaments. The transverse filaments are connected along their centers by a central element. To determine the 3-D architecture of the SC in situ, we studied frozen-hydrated meiotic yeast cell cryosections by Volta phase-contrast electron cryotomography and subtomogram analysis. We find the SC is built from triple-helical filaments that pack into dense polycrystalline bundles. These structures are also abundant in the polycomplexes of pachytene-arrested cells. Dissolution by 1,6-hexanediol treatment suggests that these triple-helical filaments belong to the central region of the SCs. Subtomogram averaging revealed that the SC’s triple-helical filaments are up to 12-nm thick and have a 5-nm rise and 130-nm pitch. Single triple-helices and polymers thinner than the triple helix, such as single or double strands, were not detected, consistent with the strong self-oligomerization properties of SC proteins. The dense packing of SC subunits supports the notion that the SC’s mechanical properties help coordinate the rapid end-to-end communication across synapsed chromosomes.

Characterization of procollagen synthesized by matrix-free cells isolated from chick embryo tendons

Biochemistry ◽  
1976 ◽  
Vol 15 (22) ◽  
pp. 4935-4942 ◽  
Author(s):  
Jouni Uitto ◽  
Jack R. Lichtenstein ◽  
Eugene A. Bauer
Keyword(s):  
Chick Embryo ◽  
Free Cells ◽  
Matrix Free

vitreal cells and specialized phagocytes in the chick embryo retina: A TEM and SEM study

1990 ◽  
Vol 48 (3) ◽  
pp. 330-331
Author(s):  
M.A. Cuadros ◽  
M.J. Martinez-Guerrero ◽  
A. Rios
Keyword(s):  
Cell Death ◽  
Plasma Membrane ◽  
Acid Phosphatase ◽  
Chick Embryo ◽  
Basement Membrane ◽  
Sem Images ◽  
Intimate Contact ◽  
Cellular Processes ◽  
Sem Study ◽  
Free Cells

In the chick embryo retina (days 3-4 of incubation), coinciding with an increase in cell death, specialized phagocytes characterized by intense acid phosphatase activity have been described. In these preparations, all free cells in the vitreal humor (vitreal cells) were strongly labeled. Conventional TEM and SEM techniques were used to characterize them and attempt to determine their relationship with retinal phagocytes.Two types of vitreal cells were distinguished. The first are located at some distance from the basement membrane of the neuroepithelium, and are rounded, with numerous vacuoles and thin cytoplasmic prolongations. Images of exo- and or endocytosis were frequent; the cells showed a well-developed Golgi apparatus (Fig. 1) In SEM images, the cells was covered with short cellular processes (Fig. 3). Cells lying parallel to or alongside the basement membrane are elongated. The plasma membrane is frequently in intimate contact with the basement membrane. These cells have generally a large cytoplasmic expansion (Fig. 5).

Bacterial microencapsulation with three algal polysaccharides

1997 ◽  
Vol 43 (11) ◽  
pp. 1091-1095 ◽  
Author(s):  
Terry B. Hammill ◽  
Ronald L. Crawford
Keyword(s):  
Aqueous Medium ◽  
Guar Gum ◽  
Cell Suspensions ◽  
Type I ◽  
Type Ii ◽  
Degradation Rates ◽  
Degrading Bacteria ◽  
Free Cells ◽  
Algal Polysaccharides ◽  
Pressure Nozzle

Methods for encapsulating pollutant-degrading bacteria into microbeads of carrageenan type I, carrageenan type II, and guar gum are described. Cell suspensions in solutions of encapsulating agents were passed through a low-pressure nozzle into an aqueous medium. The resultant aerosols polymerized to form microbeads that ranged in diameter from 2–70 μm. Pentachlorophenol degradation experiments with an encapsulated Sphingomonas sp. showed degradation rates similar to those seen using free cells. These results describe three additional matrices for the microencapsulation of bacteria that have potential for use in bioremediation processes.Key words: Sphingomonas, pentachlorophenol, immobilization, encapsulation, bioremediation.

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