Biochemical Studies on the Early Development of the Sea Urchin

In vitro incorporation of amino acids into proteins stimulated by RNA from unfertilized sea urchin eggs.

The effect of sea water on cytochrome oxidase and oxidative phosphorylation.

Piccole quantita di acqua di mare causano una forte inibizione della fosforilazione ossidativa, mentre l'effetto sulla attivita citocromossidasica e piuttosto modesto. L'ione responsabile di questo effetto e il Calcio.

Cytochrome oxidase activity in the mitochondria of unfertilized and fertilized sea urchin eggs

Abstract The cytochrome oxidase activity of isolated mitochondria of unfertilized and fertilized eggs of Paracentrotus lividus has been studied. It has been found that whereas in the mitochondria of unfertilized eggs saturation is reached at a cytochrome c concentration of 3.28 × 10−5 M, in those of fertilized eggs this occurs at a concentration of 5.74 × 10−5 M. It is shown that upon fertilization an increase of about 30 per cent of the activity of cytochrome oxidase takes place and no further changes appear to occur until blastula stage.

Inhibitor of the Cytochrome Oxidase of Unfertilized Sea Urchin Eggs

IN a previous communication1 the presence of an inhibitor of cytochrome oxidase in the unfertilized sea urchin egg was described. It was shown that its activity decreases considerably following fertilization, that it is a low-molecular compound, that it is heat- and alkali-labile and that its action is of a competitive type.

The cytochrome system in mitochondria of unfertilized sea urchin eggs

Abstract 1. 1. The cytochrome system of unfertilized sea urchin eggs has been studied using preparations of isolated mitochondria. 2. 2. The difference spectra of isolated mitochondria show the presence of a complete and operating cytochrome system formed by the cytochromes a , a 3 , b and c . 3. 3. This cytochrome system is very similar to that of mammals and yeast as demonstrated by spectrophotometric and manometric experiments.

An Inhibitor of Cytochrome Oxidase Activity in the Sea Urchin Egg

PREVIOUS work in this laboratory1,2 has demonstrated the presence of a highly active cytochrome oxidase in the isolated mitochondria of unfertilized sea urchin eggs. This activity is only 25 per cent lower than that of the mitochondria of the newly fertilized egg and up to the blastula stage2. No cytochrome oxidase activity has been found other than in the mitochondria1,3. On the other hand, it is known that the oxygen consumption of the unfertilized sea urchin egg is quite low; fertilization restores a normal respiratory level which increases continuously during the early development (for a discussion, see ref. 4). The suggestion was then made2 that in the unfertilized egg an extra-mitocho…