222
SILVIO RANZI
The salting-out diagram of an adult animal is different: the four peaks
are at 10, 35, 55 and 85% of ammonium sulphate saturation (Fig. 11).
The peak at 35% corresponds to that of adult myosin prepared according to Szent-Györgyi, while the peak at 60% is that of actin.
In order to identify the different fractions, we used colour reactions
(Dische's for DNA, orcinol for RNA, and benzidine) as well as immunological reactions.
Dische's reaction is positive after the yolk plug gastrula stage in
fractions precipitating between 45 and 70% of ammonium sulphate
saturation, but after neurulation the fraction that precipitates between
30 and 45% also shows this reaction.
The RNA reaction is evident at the yolk plug stage in the fraction
precipitating between 45 and 65% of ammonium sulphate saturation,
but this fraction increases during development, and at the end of it the
fraction precipitating between 30 and 75% of ammonium sulphate
saturation shows the reaction. This fact may be related to the synthesis
of new ribonucleoproteins.
The benzidine reaction appears in all the fractions precipitating between 45 and 70% of ammonium sulphate saturation at the neural fold
stage but by the end of development all the fractions precipitating between 0 and 85% of ammonium sulphate saturation show the reaction.
An investigation was made (Fig. 12) to test the appearance of different antigens during embryonic development. The toad egg extract does
not precipitate with the rabbit antiserum prepared against the adult
male toad (total body). The first precipitin reaction occurs during
cleavage. In the fraction where myosin will appear during later development, precipitation first occurs at the late blastula stage, while precipitation with anti-myosin and precipitation with anti-actin sera both occur
in the late gastrula stage (Ranzi and Citterio, 1955a,b). These data
are in good agreement with those of Ebert (1955), who noted the appearance of the antigen of cardiac myosin in the chick embryo at the stage
of the primitive streak. This stage can be considered as homologous to
the stage of late gastrulation in the frog. During later development new
antigens gradually appear.
During development some of these antigens undergo changes which
may be considered as a molecular ontogenesis. In the gastrulae and
neurulae of Bufo bufo, antigens (or groups of antigens) are present in
those fractions which precipitate from a solution in Weber and Edsall
fluid at a concentration of ammonium sulphate between 30 and 50%
and between 50 and 70% of saturation. These fractions are precipitated
by a serum prepared against the adult body of Bufo bufo while they are
not precipitated by a serum prepared against the adult body of Bufo
viridis. In both of these fractions, at the tail bud stage, antigens
SILVIO RANZI
The salting-out diagram of an adult animal is different: the four peaks
are at 10, 35, 55 and 85% of ammonium sulphate saturation (Fig. 11).
The peak at 35% corresponds to that of adult myosin prepared according to Szent-Györgyi, while the peak at 60% is that of actin.
In order to identify the different fractions, we used colour reactions
(Dische's for DNA, orcinol for RNA, and benzidine) as well as immunological reactions.
Dische's reaction is positive after the yolk plug gastrula stage in
fractions precipitating between 45 and 70% of ammonium sulphate
saturation, but after neurulation the fraction that precipitates between
30 and 45% also shows this reaction.
The RNA reaction is evident at the yolk plug stage in the fraction
precipitating between 45 and 65% of ammonium sulphate saturation,
but this fraction increases during development, and at the end of it the
fraction precipitating between 30 and 75% of ammonium sulphate
saturation shows the reaction. This fact may be related to the synthesis
of new ribonucleoproteins.
The benzidine reaction appears in all the fractions precipitating between 45 and 70% of ammonium sulphate saturation at the neural fold
stage but by the end of development all the fractions precipitating between 0 and 85% of ammonium sulphate saturation show the reaction.
An investigation was made (Fig. 12) to test the appearance of different antigens during embryonic development. The toad egg extract does
not precipitate with the rabbit antiserum prepared against the adult
male toad (total body). The first precipitin reaction occurs during
cleavage. In the fraction where myosin will appear during later development, precipitation first occurs at the late blastula stage, while precipitation with anti-myosin and precipitation with anti-actin sera both occur
in the late gastrula stage (Ranzi and Citterio, 1955a,b). These data
are in good agreement with those of Ebert (1955), who noted the appearance of the antigen of cardiac myosin in the chick embryo at the stage
of the primitive streak. This stage can be considered as homologous to
the stage of late gastrulation in the frog. During later development new
antigens gradually appear.
During development some of these antigens undergo changes which
may be considered as a molecular ontogenesis. In the gastrulae and
neurulae of Bufo bufo, antigens (or groups of antigens) are present in
those fractions which precipitate from a solution in Weber and Edsall
fluid at a concentration of ammonium sulphate between 30 and 50%
and between 50 and 70% of saturation. These fractions are precipitated
by a serum prepared against the adult body of Bufo bufo while they are
not precipitated by a serum prepared against the adult body of Bufo
viridis. In both of these fractions, at the tail bud stage, antigens