ABSTRACT
Metallothionein presence and amount were determined in the unfertilized eggs of six sea urchin species by silver saturation assay and gel-chromatography of cell extracts. The results showed high levels of metallothionein in the egg cytoplasm of the two Mediterranean species Paracentrotus lividus and Sphaerechinus granularis. No metallothionein was found either in the eggs of Arbacia lixula, or in those of the three Eastern species Strongylocentrotus intermedius, Temnopleurus hardwickii and Clypeaster japonicus. However, the extracts of the latter three species revealed the presence of zinc bound in a macromolecular form, thus suggesting the existence of metal-binding proteins distinct from metallothioneins.
Subject(s)
Egg Proteins/isolation & purification , Metallothionein/isolation & purification , Oocytes/chemistry , Sea Urchins/metabolism , Animals , Chromatography, Gel , Egg Proteins/metabolism , Electrophoresis, Polyacrylamide Gel , Metallothionein/metabolism , Protein Binding , Species Specificity , Zinc/metabolismABSTRACT
The adenylate cyclase of the sea urchin egg is stimulated by dopamine in the presence of GTP. The enzyme activity is strongly enhanced when Gpp (NH)p is substituted for GTP, or after cholera toxin treatment. Gramine, an indolamine derivative, brings about non-competitive inhibition of the dopamine-stimulated adenylate cyclase activity. Pertussis toxin causes an attenuation of the gramine-induced inhibition of adenylate cyclase. These results show that dopamine and indolamine derivatives partecipate in the regulation of the adenylate cyclase activity of the sea urchin egg.
Subject(s)
Adenylyl Cyclases/metabolism , Alkaloids/pharmacology , Dopamine/pharmacology , Adenosine Diphosphate Ribose/metabolism , Adenylate Cyclase Toxin , Animals , Cholera Toxin/pharmacology , Dose-Response Relationship, Drug , Guanosine Triphosphate/pharmacology , Guanylyl Imidodiphosphate/pharmacology , Indole Alkaloids , Pertussis Toxin , Sea Urchins , Virulence Factors, Bordetella/pharmacologyABSTRACT
The mRNA populations of control and 8-days-denervated adult rat gastrocnemius have been analysed by the translation assay and the cDNA-mRNA molecular hybridization technique. This analysis demonstrates the appearance of marked changes in many of the mRNA sequences present in muscle fibres following denervation and thus gives strong support to the hypothesis that the motoneurons are able to control the gene expression of muscle fibres.
Subject(s)
Gene Expression Regulation , Motor Neurons/physiology , Muscles/metabolism , RNA, Messenger/metabolism , Animals , Denervation , Genes, Synthetic , Male , Muscle Proteins/analysis , Muscles/innervation , Nucleic Acid Hybridization , Protein Biosynthesis , RatsABSTRACT
Experiments are reported showing that following 8 days of denervation the function of the protein-synthesizing machinery, operating in the rat gastrocnemius fibres, is altered, probably as a consequence of decreased amounts of ribosomes and actively translated mRNA. In addition, the data obtained show that the amount per muscle and the availability per ribosome of the soluble factors involved in the process of protein synthesis are markedly decreased, thus suggesting that the amounts of ribosomes, mRNA and soluble factors are regulated in a concerted fashion when muscular protein synthesis is decreased after denervation.
