236
S I L V I O R A N Z I
T A B L E l
Percentage of dissolved protein precipitating a t 5 0 % of a m m o n i u m sulphate
saturation
Li-treated
Control
I B A - t r e a t e d SCN-treated
Rana embryo
Bufo bufo embryoj
Euglobulin a + b from
frog egg
Lipovitellin from hen
eggt
64-75 ±1-03
64-8 ± 1 0
82-2 ±0-81
69-0
58-0 + 1-12
57-5 ±0-47
76-2+0-48
54-8 + 1-8
36-6
49-8+2-17
59-2 ±0-84
33-8
t The value for the non-viable hybrid (B. viridis ? x ß . bufo <£) is 64-6±0-96; for
B. viridis it is 55-8 + 0-92.
{ Values correspond to the precipitation at 2 5 % of ammonium sulphate saturation.
0 10 20 30 40 50 60 70 80 90 C
FIG. 27. Salting-out diagram for non-viable hybrid Bufo viridis $ x B. bufo $ (VB);
B. bufo (control) and Li-treated B. bufo embryo (redrawn from Ranzi, Citterio and
Samuelli, 1960).
an experimental agent. Consequently the changes in the proteins extracted from these embryos cannot be related to a foreign ion remaining
bound to them.
It is necessary to discuss the nature of the different protein precipitation of embryos treated with LiCl or NaSCN. There may be a difference
in physico-chemical properties of certain proteins or there may be a
synthesis of new proteins. In order to check this point, we extracted the
proteins from lyophilized frog eggs by means of a 1 M-KC1 solution and
after lipid extraction with ethyl ether we precipitated them by dilution
to a 0-3 M-concentration. The precipitate was then dissolved in 1 M-KC1.