Essential role of the polyamines in early chick embryo development

Development ◽  
1980 ◽  
Vol 60 (1) ◽  
pp. 83-92
Author(s):  
B. Löwkvist ◽  
O. Heby ◽  
H. Emanuelsson
Keyword(s):  
Essential Role ◽  
Decisive Role ◽  
Chick Embryos ◽  
Irreversible Inhibitor ◽  
In Ovo ◽  
Polyamine Synthesis ◽  
Major Increase ◽  
Rate Limiting ◽  
Second Peak

The polyamines putrescine, spermidine and spermine were analyzed in chick embryos during the first 2 days of development. A rapid increase in the activity of ornithine decarboxylase (ODC), the initial and rate-limiting enzyme in polyamine synthesis, was observed immediately after onset of incubation. Peak activities were found at 15 and 23 h of incubation. The first peak coincides with gastrulation and the second peak with early neurulation in the embryo. All three polyamines varied in a similar manner as did ODC, with putrescine and spermidine at about the same level and spermine at a lower level. The ODC activity was blocked by α-difluoromethylornithine, an enzyme-activated irreversible inhibitor. The inhibitor was administered to embryos in ovo at 5 h of incubation, i.e. prior to the first major increase in ODC activity. This block prevented the accumulation of the polyamines and inhibited development at gastrulation, suggesting a decisive role for polyamines in this developmental event.

scholarly journals Role of haem in the induction of cytochrome P-450 by phenobarbitone. Studies in chick embryos in ovo and in cultured chick embryo hepatocytes

1981 ◽  
Vol 198 (2) ◽  
pp. 321-329 ◽  
Author(s):  
U Giger ◽  
U A Meyer
Keyword(s):  
Chick Embryo ◽  
Inhibitory Effect ◽  
Chick Embryos ◽  
In Ovo ◽  
Haem Biosynthesis ◽  
Rate Limiting ◽  
Cytochrome P 450 ◽  
Hepatic Cytochrome

The role of haem synthesis during induction of hepatic cytochrome P-450 haemoproteins was studied in chick embryo in ovo and in chick embryos hepatocytes cultured under chemically defined conditions. 1. Phenobarbitone caused a prompt increase in the activity of 5-aminolaevulinate synthase, the rate-limiting enzyme of haem biosynthesis, and in the concentration of cytochrome P-450. This induction response occurred without measurable initial destruction of the haem moiety of cytochrome P-450. 2. When intracellular haem availability was enhanced by exogenous haem or 5-aminolaevulinate, phenobarbitone-medicated induction of cytochrome P-450 was not affected in spite of the well known repression of 5-aminolaevulinate synthase by haem. These data are consistent with the concept that haem does not regulate the synthesis of cytochrome P-450 haemoproteins. 3. Acetate inhibited haem biosynthesis at the level of 5-aminolaevulinate formation. When intracellular haem availability was diminished by treatment with acetate, phenobarbitone-medicated induction was decreased. 4. This inhibitory effect of acetate on cytochrome P-450 induction was reversed by exogenous haem or its precursor 5-aminolaevulinate. These data suggest that inhibition of haem biosynthesis does not decrease synthesis of apo-cytochrome P-450. Moreover, they indicate that exogenous haem can be incorporated into newly formed aop-cytochrome P-450.

scholarly journals The inhibition of lysyl oxidase in vivo by isoniazid and its reversal by pyridoxal. Effect on collagen cross-linking in the chick embryo

1984 ◽  
Vol 221 (3) ◽  
pp. 837-843 ◽  
Author(s):  
M J Carrington ◽  
T A Bird ◽  
C I Levene
Keyword(s):  
Pyridoxal Phosphate ◽  
Isonicotinic Acid ◽  
Lysyl Oxidase ◽  
Acid Hydrazide ◽  
Chick Embryos ◽  
Cross Link ◽  
Irreversible Inhibitor ◽  
Link Formation

Isonicotinic acid hydrazide (isoniazid) causes a large increase in the salt-solubility of collagen when injected into chick embryos; this change is accompanied by the inactivation of lysyl oxidase (EC 1.4.3.13), the enzyme responsible for initiating cross-link formation in collagen and elastin. In addition, isoniazid markedly decreases the liver content of pyridoxal phosphate. The depletion of pyridoxal phosphate takes approx. 6 h, whereas the inhibition of lysyl oxidase and the increase in collagen solubility occur more slowly. A reversal of these effects of isoniazid can be produced by the subsequent injection of a stoichiometric amount of pyridoxal, supporting the role of pyridoxal as a cofactor for lysyl oxidase. Treatment of chick embryos with beta-aminopropionitrile, an irreversible inhibitor of lysyl oxidase, causes an inhibition of the enzyme, which begins to recover within 24 h but which is not affected by the administration of pyridoxal; with isoniazid inhibition, however, lysyl oxidase activity does not show any sign of recovery by 48 h. It is proposed that isoniazid may cause the inhibition of lysyl oxidase by competing for its obligatory cofactor, pyridoxal phosphate. The potential clinical implications in the therapeutic control of fibrosis are briefly discussed.

scholarly journals Drug-induced accumulation of uroporphyrin in chicken hepatocyte cultures. Structural requirements for the effect and role of exogenous iron

1984 ◽  
Vol 224 (3) ◽  
pp. 769-777 ◽  
Author(s):  
A Ferioli ◽  
C Harvey ◽  
F De Matteis
Keyword(s):  
Chick Embryo ◽  
Molecular Target ◽  
Chick Embryos ◽  
In Ovo ◽  
Drug Induced ◽  
Structural Requirements ◽  
Binding Characteristics ◽  
Alternative Hypotheses ◽  
Do So

The ability of drugs to cause uroporphyria in hepatocytes from 17-day-old chick embryos has been investigated and the response of the cells in culture compared with that of the intact liver of the embryos in ovo. In this chick-embryo system, drugs that cause accumulation of uroporphyrin within 19-24 h can only do so in culture; in contrast, 2-allyl-2-isopropylacetamide and 3,5-diethoxycarbonyl-1,4-dihydrocollidine, which stimulate production of protoporphyrin, are effective both in culture and in ovo. A role of exogenous iron in worsening drug-induced uroporphyria was demonstrated in cultures of hepatocytes; iron also caused preferential accumulation of uroporphyrin from added 5-aminolaevulinate in the absence of a porphyrogenic chemical. Uroporphyria was induced in cultures of hepatocytes by drugs of widely different structures, suggesting that the primary molecular target with which they interact may be relatively aspecific in its binding characteristics. These results are briefly discussed, and two alternative hypotheses for the drug-induced effect in uroporphyrinogen metabolism are considered.

scholarly journals Inhibition of spermidine formation in rat liver and kidney by methylglyoxal bis(guanylhydrazone)

1973 ◽  
Vol 132 (3) ◽  
pp. 537-540 ◽  
Author(s):  
A. E. Pegg
Keyword(s):  
Rat Liver ◽  
Intraperitoneal Injection ◽  
Essential Role ◽  
Complete Inhibition ◽  
Polyamine Metabolism ◽  
Polyamine Synthesis ◽  
Liver And Kidney

The effect of methylglyoxal bis(guanylhydrazone), a substance known to inhibit putrescine-dependent S-adenosyl-l-methionine decarboxylase, on polyamine metabolism in liver and kidney was investigated. Almost complete inhibition of the incorporation of putrescine into spermidine was obtained up to 8h after administration of 80mg of methylglyoxal bis(guanylhydrazone)/kg body wt. by intraperitoneal injection. However, by 20h after administration of the inhibitor spermidine synthesis was resumed. Considerable accumulation of putrescine occurred during this period (up to 3 times control concentrations in both tissues), but there was only a slight fall in the spermidine content. These results suggest that the putrescine-activated S-adenosyl-l-methionine decarboxylase plays an essential role in spermidine biosynthesis in rat liver and kidney, and the possibility of using methylglyoxal bis(guanylhydrazone) to study the role of polyamine synthesis in growth is discussed.

scholarly journals The Essential Role Of Renewable Energy In A Sustainable Future

2011 ◽  
Vol 5 (12) ◽  
Author(s):  
Patricia T. Papachristou ◽  
Gerald C. Papachristou
Keyword(s):  
Renewable Energy ◽  
Essential Role ◽  
Decisive Role ◽  
National Government ◽  
Significant Part ◽  
Sustainable Future ◽  
Government Incentives ◽  
Private Corporations ◽  
Cost Efficient

This paper examines why renewable energy is essential to building a healthy, reliable, and secure future, that ultimately, will be both more cost efficient and beneficial to the environment. Despite the reluctance of the American national government to commit itself to renewable energy, several countries and California are demonstrating how renewable energy can become a significant part of their economy in less than a decade. While private corporations are important, government incentives and disincentives play a decisive role in the successful conversion to renewables.

The role of movement in the development of joints and related structures: the head and neck in the chick embryo

Development ◽  
1969 ◽  
Vol 22 (3) ◽  
pp. 349-371
Author(s):  
P. D. F. Murray ◽  
Daniel B. Drachman
Keyword(s):  
Skeletal Muscle ◽  
Chick Embryo ◽  
Normal Development ◽  
Neuromuscular Blocking ◽  
Neuromuscular Blocking Agents ◽  
Chick Embryos ◽  
In Ovo ◽  
Joint Development ◽  
Embryonic Life

Skeletal muscle contractions are necessary during embryonic life for the normal development of joints. The general features of joint development in immobile limbs were first studied with the techniques of grafting and organ culture. (Murray, 1926; Murray & Selby, 1930; Fell, 1925; Fell & Canti, 1934; Hamburger & Waugh, 1940; Lelkes, 1958). However, these methods of necessity entail a drastic alteration in the environment of the developing articulations, which may result in gross distortions of the skeletal structures themselves. More recently, neuromuscular blocking agents have been used to produce paralysis of chick embryos in ovo. When administered intravenously, these pharmacological substances produce profound paralysis, which may be continued for prolonged periods during embryonic development (Drachman & Coulombre, 1962a, b). Drachman & Sokoloff (1966) have analyzed the primary development of the knee, ankle and toe joints of the chick embryo by the use of these methods.

Essential role of Sharpin in TNFα dependent NFκB activation in primary hepatocytes

2012 ◽  
Vol 50 (01) ◽  
Author(s):  
N Lange ◽  
S Sieber ◽  
A Erhardt ◽  
G Sass ◽  
HJ Kreienkamp ◽  
...  
Keyword(s):  
Essential Role ◽  
Primary Hepatocytes

Different Abilities of Thrombin Receptor Activating Peptide and Thrombin to Induce Platelet Calcium Rise and Full Release Reaction

1995 ◽  
Vol 74 (05) ◽  
pp. 1323-1328 ◽  
Author(s):  
Dominique Lasne ◽  
José Donato ◽  
Hervé Falet ◽  
Francine Rendu
Keyword(s):  
Essential Role ◽  
Calcium Influx ◽  
Dense Granule ◽  
Receptor Interaction ◽  
Thrombin Receptor ◽  
Release Reaction ◽  
External Calcium ◽  
Maximum Rise ◽  
Granule Release

SummarySynthetic peptides (TRAP or Thrombin Receptor Activating Peptide) corresponding to at least the first five aminoacids of the new N-terminal tail generated after thrombin proteolysis of its receptor are effective to mimic thrombin. We have studied two different TRAPs (SFLLR, and SFLLRN) in their effectiveness to induce the different platelet responses in comparison with thrombin. Using Indo-1/AM- labelled platelets, the maximum rise in cytoplasmic ionized calcium was lower with TRAPs than with thrombin. At threshold concentrations allowing maximal aggregation (50 μM SFLLR, 5 μM SFLLRN and 1 nM thrombin) the TRAPs-induced release reaction was about the same level as with thrombin, except when external calcium was removed by addition of 1 mM EDTA. In these conditions, the dense granule release induced by TRAPs was reduced by over 60%, that of lysosome release by 75%, compared to only 15% of reduction in the presence of thrombin. Thus calcium influx was more important for TRAPs-induced release than for thrombin-induced release. At strong concentrations giving maximal aggregation and release in the absence of secondary mediators (by pretreatment with ADP scavengers plus aspirin), SFLLRN mobilized less calcium, with a fast return towards the basal level and induced smaller lysosome release than did thrombin. The results further demonstrate the essential role of external calcium in triggering sustained and full platelet responses, and emphasize the major difference between TRAP and thrombin in mobilizing [Ca2+]j. Thus, apart from the proteolysis of the seven transmembrane receptor, another thrombin binding site or thrombin receptor interaction is required to obtain full and complete responses.

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