5. Radioactive Labelling of MSH and MCH

2015 ◽  
pp. 65-78
Keyword(s):  
Radioactive Labelling

On the Chemistry of Phorbol, XIX [1] Preparation of Tritium-Labelled 12-O-RetinoyIphorbol-13-acetate([20-3H]-RPA)

1988 ◽  
Vol 43 (12) ◽  
pp. 1672-1675 ◽  
Author(s):  
G. L. Tremp ◽  
E. Hecker
Keyword(s):  
Retinoic Acid ◽  
Sodium Borohydride ◽  
Specific Activity ◽  
Diterpene Esters ◽  
Highly Sensitive ◽  
Radioactive Labelling

Abstract In contrast to established principles of radioactive labelling of diterpene esters such as TPA it was impossible to introduce tritium into the highly sensitive 12-0-retinoylphorbol-13-acetate (RPA) via reduction of its cold 20-aldehyde with [3H]-sodium borohydride. As an alternative successful procedure, [20-3H]-phorbol-13-acetate was prepared at first. It was protected in position 20 by reaction with tritylchloride and the tritylether reacted with retinoic acid. In both reactions appropriate phorbol acetates were used as easy to separate cold carriers. After removal of the 20-tritylether group, [20-3H]-RPA of a specific activity was obtained that was sufficient for the compound to be used as a tool in biochemical investigations

scholarly journals The inhibition of platelet cyclo-oxygenase by aspirin is associated with the acetylation of a 72kDa polypeptide in the intracellular membranes

1984 ◽  
Vol 223 (1) ◽  
pp. 105-111 ◽  
Author(s):  
N Hack ◽  
F Carey ◽  
N Crawford
Keyword(s):  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Membrane System ◽  
Particulate Material ◽  
Intracellular Membrane ◽  
Membrane Structures ◽  
Major Site ◽  
Intracellular Membranes ◽  
Oxygenase Activity ◽  
Radioactive Labelling

Previous studies by Roth & Majerus [J. Clin. Invest. (1975) 56, 624-632] showed that exposure of platelets to [acetyl-14C]aspirin resulted in the radioactive labelling of three polypeptides, two of which were in the cytosol and not saturable, whilst the third was located in particulate material, and was saturated at 30 microM-aspirin. By using high voltage free flow electrophoresis to separate a platelet mixed membrane fraction into highly purified surface and intracellular membrane subfractions, we have confirmed that the major polypeptide acetylated after exposing whole platelets to [acetyl-14C]aspirin is almost exclusively associated with intracellular membrane structures. We have shown previously that these intracellular membranes are the major site for prostanoid biosynthesis [Carey, Menashi & Crawford (1982) Biochem. J. 204, 847-851] and in the present study the extent of the radioactive labelling correlated well with inhibition of the cyclo-oxygenase activity in these intracellular membranes. In sodium dodecyl sulphate/polyacrylamide-gel electrophoresis the [14C]acetylated component, which appears to be a dimer, migrates with a mobility corresponding to 72kDa. Although cyclo-oxygenase is inhibited, there is no discernible radioactive labelling when the platelets are exposed to aromatic-ring-labelled [14C]aspirin. We suggest that the site or sites for aspirin acetylation and cyclo-oxygenase activity are structurally associated in the platelet's intracellular membranes referred to by electron microscopists as the dense tubular membrane system.

Radioactive labelling of the attachment site of C3

Pathology ◽  
1983 ◽  
Vol 15 (3) ◽  
pp. 346
Author(s):  
C.J. Rutherford ◽  
B.M. Babior
Keyword(s):  
Attachment Site ◽  
Radioactive Labelling

Localization and synthesis of alphafoetoprotein in post-implantation mouse embryos

Development ◽  
1978 ◽  
Vol 43 (1) ◽  
pp. 289-313
Author(s):  
M. Dziadek ◽  
E. Adamson
Keyword(s):  
Yolk Sac ◽  
Mouse Embryos ◽  
Visceral Endoderm ◽  
Mouse Embryogenesis ◽  
Visceral Yolk Sac ◽  
Radioactive Labelling ◽  
Post Implantation ◽  
Embryonic Ectoderm ◽  
Embryonic Region

The localization and synthesis of alphafoetoprotein (AFP) during mouse embryogenesis were studied by immunoperoxidase and by immunoprecipitation after radioactive labelling, using an antiserum prepared against AFP. AFP is first detectable in embryos on the 7th day of gestation (7th day embryos). In 7th and 8th day embryos AFP is confined to visceral (proximal) endoderm cells around the embryonic region of the egg cylinder. Visceral extra-embryonic and parietal (distal) endoderm cells do not contain AFP. By the 9th day of gestation AFP is also present in the extra-embryonic ectoderm, mesoderm and embryonic ectoderm cells around the three cavities of the embryo. These tissues do not synthesize AFP when cultured in isolation, but can adsorb AFP when it is added to the medium. On the 12th day of gestation AFP synthesis is confined to the endoderm layer of the visceral yolk sac. It is concluded that the ability to synthesize AFP is a property which is restricted to the visceral endoderm during early post-implantation development. The presence of AFP in other tissues of the embryo appears to be due to adsorption.

The Heat-Shock Response Relevant to Molecular and Structural Changes in Wheat Yield and Quality

1994 ◽  
Vol 21 (6) ◽  
pp. 901 ◽  
Author(s):  
C Blumenthal ◽  
CW Wrigley ◽  
IL Batey ◽  
EWR Barlow
Keyword(s):  
Heat Stress ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Structural Changes ◽  
De Novo ◽  
Wheat Yield ◽  
Radioactive Tracer ◽  
Gluten Proteins ◽  
Radioactive Labelling ◽  
Shock Proteins

When wheat coleoptiles or plants are subjected to a period of heat stress (e.g, at > 35�C for 1 h or more), there is a reduction in normal protein synthesis, accompanied by de novo synthesis of the classical range of heat-shock proteins (based on radioactive tracer experiments) in virtually all parts of the plant. Study of coleoptile elongation rates indicates that this synthesis is related to a protective effect, whereby a preliminary heat shock provides a degree of protection against a later lethal shock. This thermotolerance is also associated with the appearance in coleoptiles and roots of a small peptide (detected without radioactive labelling) whose amino acid sequence (12 residues) is the same as the N-terminal sequence of the alpha- and beta-gliadin proteins of the endosperm. Heat stress during grain filling leads to important changes in the synthesis of gluten proteins with reduced synthesis of the high molecular weight (HMW) subunits of glutenin, and continuing synthesis of other gluten proteins, particularly various gliadin proteins. This latter group of polypeptides is thus presumed to be acting as heat-shock proteins, and indeed, multiple heat-shock elements are present in the published sequences of representative genes, up-stream of the coding regions. HPLC analysis (with or without radioactive labelling) shows that there is a resulting change from the normal balance of gluten polypeptides immediately after the shock as well as in the mature grain. As a result, there is a lower proportion of large-sized aggregates of glutenin and weaker dough properties. This scenario indicates that it should be possible to identify genotypes that would be tolerant to stressrelated variations in quality by analysis of gluten composition and, at the gene level, by screening for heat-stress elements in the genes encoding HMW-glutenin subunits. In addition, heat stress modifies the particle size distribution of the starch fraction of mature grain, producing an increase in the proportion of large (A-type) starch granules. No change in chemical structure was detectable as a result of heat stress.

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