244
S I L V I O R A N Z I
0-304E275
0I
4
7
10
13
16
19 min.
FIG. 34. Effect on hen egg lipovitellin of incubation with^NaSCN, IB A or LiCl, on
subsequent digestion by trypsin for various periods as shown on the abscissa; the differences between the values at time 1 (extinction value 0-360) and subsequent readings
are shown on the ordinate.
observed when trypsin is used instead of urea and the digestion rate is
studied.
F. Differences in Resistance to Breakdown of Proteins
from Embryos Showing Different Malformations
It is obvious that if the above phenomena are important in the changes
of embryonic determination, something must be observable in the
embryo itself after treatment with vegetalizing or animalizing substances. To verify this point we carried out the following experiments
with the sea urchin (Arbacia lixula). Control embryos and embryos
treated with IBA, NaSCN, or LiCl were allowed to develop to the stage
of the young blastula and were then lyophilized. The powder was extracted overnight in 1 M-KC1. Euglobulin a + b was precipitated by dilution and dissolved in 1 M-KC1. The four solutions [(i) euglobulin of control embryos; (ii) euglobulin of vegetalized embryos; (iii) euglobulin of
embryos animalized by IBA; (iv) euglobulin of embryos animalized by
NaSCN] were diluted in such a way as to reach the same optical density
at 280 m/x in the Beckman spectrophotometer. From each solution the
following samples were prepared: (a) euglobulin a + b diluted 1 : 1 with
the solvent (1 M-KC1); (b) euglobulin a + b diluted 1 : 1 with 30% urea;
(c) euglobulin a + b diluted 1 : 1 with trypsin (Merck) dissolved in 1M-KC1
kept at p H 7-9 with Weber and Edsall fluid; (d) euglobulin a + b diluted
1 : 1 with papain in 1 M-NaCl. After a four-hour incubation in the visP NaSCN
*IBA
Contr.
LiCl
S I L V I O R A N Z I
0-304E275
0I
4
7
10
13
16
19 min.
FIG. 34. Effect on hen egg lipovitellin of incubation with^NaSCN, IB A or LiCl, on
subsequent digestion by trypsin for various periods as shown on the abscissa; the differences between the values at time 1 (extinction value 0-360) and subsequent readings
are shown on the ordinate.
observed when trypsin is used instead of urea and the digestion rate is
studied.
F. Differences in Resistance to Breakdown of Proteins
from Embryos Showing Different Malformations
It is obvious that if the above phenomena are important in the changes
of embryonic determination, something must be observable in the
embryo itself after treatment with vegetalizing or animalizing substances. To verify this point we carried out the following experiments
with the sea urchin (Arbacia lixula). Control embryos and embryos
treated with IBA, NaSCN, or LiCl were allowed to develop to the stage
of the young blastula and were then lyophilized. The powder was extracted overnight in 1 M-KC1. Euglobulin a + b was precipitated by dilution and dissolved in 1 M-KC1. The four solutions [(i) euglobulin of control embryos; (ii) euglobulin of vegetalized embryos; (iii) euglobulin of
embryos animalized by IBA; (iv) euglobulin of embryos animalized by
NaSCN] were diluted in such a way as to reach the same optical density
at 280 m/x in the Beckman spectrophotometer. From each solution the
following samples were prepared: (a) euglobulin a + b diluted 1 : 1 with
the solvent (1 M-KC1); (b) euglobulin a + b diluted 1 : 1 with 30% urea;
(c) euglobulin a + b diluted 1 : 1 with trypsin (Merck) dissolved in 1M-KC1
kept at p H 7-9 with Weber and Edsall fluid; (d) euglobulin a + b diluted
1 : 1 with papain in 1 M-NaCl. After a four-hour incubation in the visP NaSCN
*IBA
Contr.
LiCl