264
J E A N B R Ä C H E T
FIG. 9. Dorsal lip of frog gastrula irreversibly blocked by a heat shock.
All these experiments d e m o n s t r a t e t h a t R N A , or constituents closely
associated t o R N A in t h e ribosomes or microsomes, m u s t p l a y a n
essential role in morphogenesis.
3. Effects of Eibonuclease (RNase) on Morphogenesis
A t t e m p t s h a v e been m a d e b y B r ä c h e t a n d L e d o u x (1955) a n d
B r ä c h e t (1959) t o give a direct d e m o n s t r a t i o n of t h e role p l a y e d b y
gastrula stage) or b y lethal hybridization, overall R N A synthesis stops.
If a piece of t h e blocked g a s t r u l a is grafted into a n o r m a l host, 'revitalization' of t h e graft quickly results in a r e s u m p t i o n of R N A synthesis in
t h e cytoplasm as well as t h e nucleus (Figs. 9, 10).
J E A N B R Ä C H E T
FIG. 9. Dorsal lip of frog gastrula irreversibly blocked by a heat shock.
All these experiments d e m o n s t r a t e t h a t R N A , or constituents closely
associated t o R N A in t h e ribosomes or microsomes, m u s t p l a y a n
essential role in morphogenesis.
3. Effects of Eibonuclease (RNase) on Morphogenesis
A t t e m p t s h a v e been m a d e b y B r ä c h e t a n d L e d o u x (1955) a n d
B r ä c h e t (1959) t o give a direct d e m o n s t r a t i o n of t h e role p l a y e d b y
gastrula stage) or b y lethal hybridization, overall R N A synthesis stops.
If a piece of t h e blocked g a s t r u l a is grafted into a n o r m a l host, 'revitalization' of t h e graft quickly results in a r e s u m p t i o n of R N A synthesis in
t h e cytoplasm as well as t h e nucleus (Figs. 9, 10).