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Dye coupling is cell cycle dependent during early Xenopus laevis development
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DYE COUPLING IS CELL CYCLE DEPENDENT DURING EARLY XENOPUS LAEVIS DEVELOPI~NT. Jiang Wansu*, A.J. Durston, L.G.J. Tertoolen and S.W. de Laat. Hubreeht Laboratory, Uppsalalaan 8, 3584 CT Utrecht, the Netherlands. * Shanghai Institute of Cell Biology, 320 Yo-Yang Road, Shanghai, China.
SUBCORTICAL ROTATION IN XENOPUS EGGS. Jean-Paul Vincent and John Gerhart. Dept of Molecular Biology, Univ. of California, Berkeley CA 94720, USA. The amphibian egg undergoes a 30° rotation of its subcortical contents relative to its surface during the first cell cycle. This is directly visualized by following the movement of an array of nile blue (a subcortical stain) spots applied to the egg periphery (Vincent et al., Dev. Biol. 113, 484). The direction of rotation is topographically related to the orientsticn of the embryonic axis. First, we have investigated the mechanochemlcal basis of this reorganization. It depends on microtubule integrity, is insensitive to inhlbltors of microfilarnent assembly, and does not involve calcium-dependent processes. Furthermore, isolated vegetal fragments can complete rotaticn on their own. Second, we tamed the developmental significance of rotation. Using non-lethal treatments (UV irradiation, egg inclination, and cold) to control the extent of rotation, we demonstatred an overall correlation, although quite variable, between the extent of movement in the vegetal hemisphere and the completeness of axial development. In all cases, no complete axis develops from an egg which underwent no movement at all. Thus rotation in the egg constitutes a cue, but does not generate precise instructions for subsequent dorsal development. From an independent line of evidence, we suspect that this early cue is located In the vegetal hemisphere. If eggs are treated with D20 at 30% of the first cell cycle, rotation is reduced in extent. Yet, "hyperdorsal development" often follows. This paradoxical result will be discussed.
We investigated the stage and cell cycle dependence of dye coupling in the animal cap of cleavage and blastula stage Xenopus laevis embryos. We found transfer of lucifer yellow and FITC dextran to sister cells, via cytoplasmic bridges, and transfer of lucifer yellow to non sister cells, via gap junctions. Transfer via cytoplasmic bridges is cell cycle dependent, because these persist transiently after each cell division. Their persistence was stage dependent, being the first 8 minutes of the cell cycle at the 64 cell stage and the first 15 minutes of the cycle at the 512 cell stage. Lucifer yellow transfer via gap junctions was also cell cycle dependent, being maximal early in the cycle and low or absent at the end. These findings may be relevant for cell interactions during early development and for the formation of developmental compartments.
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THE DEVEIEPKENT OF FISH EGGS COMBIN~I) WITH NUCLEUS FROM DIYERG~T SOURCES,6.C.W~., l~s t t t u ~ e o f O c e a n o l o g y , Academia 6 1 s l o e , Telegram, China. Mature ovum of tel~etean fish egg after activation and enu¢leation was combine/ w i t h a n u c l e u s from d i f f e r e n t ; s o u r c e s by transplantation. The eoubinen% w i l l d i v i d e and form b l a s t u l a . The b e s t s wore m e e t l y g o l d f i s h e g g , d o n o r s were o f d i v e r g e n t spoo 81.ewly d i v i d i n g b l a s t u l a o f Rhodeuo and Burs 9 c u l t u r e d human h o p a t o u a and HoLe s e l l undividlng adult rabbit neuron, blastula of A e c i d i a n and Amphlexus and p r o t e p l a s t o f m s r i w e e l s e , P e r p h y r a s p . and C e d i u u s p . I. The t4.ne f r e w i n s e r t i o n o f t h e n u c l e u s t e f i r s t c l o e v a g e was v a r i a b l e , owing t o the differem% status of the nucleus in its ow~ c y c l e , f r s m t h e s e c o n d d i v i s J o n onward i t obeyed t h e r h y t h m o f t h e b e s t ! ~. The e p t l m a l tew~porature e f devele~x, en% was s i m i l a r t o t h e h a s t c y t o p l a s m ! 3. N u c l e u s e f t h e m a r i n e s p . e a n d i v i d e well in the fresh water cytoplasm! 4. ~no n u c l e u s o f t h e p l a n t d i v i d e d b e a u t i f u l l y i n %he a n i m a l c y t o p l a s m ! 50 All cowbinente except the fis~/f1~ conn.'. bine~ died at the end ef blastula atage. T h i s I n 4 1 e a t e d %hat during s u c h e a r l y s t a g e , %he c y t o p l a s m p l a y e d a s i g n i f i c a n t r e l e on t h e d e v e l o p m e n t a l c h a r a c t e r s .
COMPARTMENTATION OF NUCLEAR PROTEINS IN THE OOCYTE AND IN EARLY EMBRYOGENESIS OF XENOPUS. F. Zimmer and C. Dre~er. MPI fur Entwlcklungsbiologie, Spemannstr. 35/V, D-7400 TUbingen, FRG. Oocyte nuclear proteins of Xenopus are distributed into the cytoplasm of the maturing egg after germinal vesicle breakdown. At early stages of development, different nuclear proteins behave differently. A class of "early shifting" antigens is accumulated by pronuclei and cleavage nuclei, whereas others are excluded from the nuclei at early stages but are shifting into the nuclei later. "Early shifting" proteins accumulate rapidly in the oocyte nucleus after de hOVe synthesis, whereas "late shifting" proteins partition between nucleus and cytoplasm. When X. borealis nuclei deprived of the envelope are injected into the cytoplasm of X. laevis oocytes, protein N] shifts from the grafted karyoplasm into the intact host nucleus. N 1 is reaccumulated less efficiently, if the host nuclear envelope is punctured. Puncturing of the nuclear envelope leeds to diffusion of nuclear protein antigens into the cytoplasm. This shows that an intact nuclear envelope is essential for the accumulation and retention of proteins in the oocyte nucleus. 120S
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DYE COUPLING IS CELL CYCLE DEPENDENT DURING EARLY XENOPUS LAEVIS DEVELOPI~NT. Jiang Wansu*, A.J. Durston, L.G.J. Tertoolen and S.W. de Laat. Hubreeht Laboratory, Uppsalalaan 8, 3584 CT Utrecht, the Netherlands. * Shanghai Institute of Cell Biology, 320 Yo-Yang Road, Shanghai, China.
SUBCORTICAL ROTATION IN XENOPUS EGGS. Jean-Paul Vincent and John Gerhart. Dept of Molecular Biology, Univ. of California, Berkeley CA 94720, USA. The amphibian egg undergoes a 30° rotation of its subcortical contents relative to its surface during the first cell cycle. This is directly visualized by following the movement of an array of nile blue (a subcortical stain) spots applied to the egg periphery (Vincent et al., Dev. Biol. 113, 484). The direction of rotation is topographically related to the orientsticn of the embryonic axis. First, we have investigated the mechanochemlcal basis of this reorganization. It depends on microtubule integrity, is insensitive to inhlbltors of microfilarnent assembly, and does not involve calcium-dependent processes. Furthermore, isolated vegetal fragments can complete rotaticn on their own. Second, we tamed the developmental significance of rotation. Using non-lethal treatments (UV irradiation, egg inclination, and cold) to control the extent of rotation, we demonstatred an overall correlation, although quite variable, between the extent of movement in the vegetal hemisphere and the completeness of axial development. In all cases, no complete axis develops from an egg which underwent no movement at all. Thus rotation in the egg constitutes a cue, but does not generate precise instructions for subsequent dorsal development. From an independent line of evidence, we suspect that this early cue is located In the vegetal hemisphere. If eggs are treated with D20 at 30% of the first cell cycle, rotation is reduced in extent. Yet, "hyperdorsal development" often follows. This paradoxical result will be discussed.
We investigated the stage and cell cycle dependence of dye coupling in the animal cap of cleavage and blastula stage Xenopus laevis embryos. We found transfer of lucifer yellow and FITC dextran to sister cells, via cytoplasmic bridges, and transfer of lucifer yellow to non sister cells, via gap junctions. Transfer via cytoplasmic bridges is cell cycle dependent, because these persist transiently after each cell division. Their persistence was stage dependent, being the first 8 minutes of the cell cycle at the 64 cell stage and the first 15 minutes of the cycle at the 512 cell stage. Lucifer yellow transfer via gap junctions was also cell cycle dependent, being maximal early in the cycle and low or absent at the end. These findings may be relevant for cell interactions during early development and for the formation of developmental compartments.
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THE DEVEIEPKENT OF FISH EGGS COMBIN~I) WITH NUCLEUS FROM DIYERG~T SOURCES,6.C.W~., l~s t t t u ~ e o f O c e a n o l o g y , Academia 6 1 s l o e , Telegram, China. Mature ovum of tel~etean fish egg after activation and enu¢leation was combine/ w i t h a n u c l e u s from d i f f e r e n t ; s o u r c e s by transplantation. The eoubinen% w i l l d i v i d e and form b l a s t u l a . The b e s t s wore m e e t l y g o l d f i s h e g g , d o n o r s were o f d i v e r g e n t spoo 81.ewly d i v i d i n g b l a s t u l a o f Rhodeuo and Burs 9 c u l t u r e d human h o p a t o u a and HoLe s e l l undividlng adult rabbit neuron, blastula of A e c i d i a n and Amphlexus and p r o t e p l a s t o f m s r i w e e l s e , P e r p h y r a s p . and C e d i u u s p . I. The t4.ne f r e w i n s e r t i o n o f t h e n u c l e u s t e f i r s t c l o e v a g e was v a r i a b l e , owing t o the differem% status of the nucleus in its ow~ c y c l e , f r s m t h e s e c o n d d i v i s J o n onward i t obeyed t h e r h y t h m o f t h e b e s t ! ~. The e p t l m a l tew~porature e f devele~x, en% was s i m i l a r t o t h e h a s t c y t o p l a s m ! 3. N u c l e u s e f t h e m a r i n e s p . e a n d i v i d e well in the fresh water cytoplasm! 4. ~no n u c l e u s o f t h e p l a n t d i v i d e d b e a u t i f u l l y i n %he a n i m a l c y t o p l a s m ! 50 All cowbinente except the fis~/f1~ conn.'. bine~ died at the end ef blastula atage. T h i s I n 4 1 e a t e d %hat during s u c h e a r l y s t a g e , %he c y t o p l a s m p l a y e d a s i g n i f i c a n t r e l e on t h e d e v e l o p m e n t a l c h a r a c t e r s .
COMPARTMENTATION OF NUCLEAR PROTEINS IN THE OOCYTE AND IN EARLY EMBRYOGENESIS OF XENOPUS. F. Zimmer and C. Dre~er. MPI fur Entwlcklungsbiologie, Spemannstr. 35/V, D-7400 TUbingen, FRG. Oocyte nuclear proteins of Xenopus are distributed into the cytoplasm of the maturing egg after germinal vesicle breakdown. At early stages of development, different nuclear proteins behave differently. A class of "early shifting" antigens is accumulated by pronuclei and cleavage nuclei, whereas others are excluded from the nuclei at early stages but are shifting into the nuclei later. "Early shifting" proteins accumulate rapidly in the oocyte nucleus after de hOVe synthesis, whereas "late shifting" proteins partition between nucleus and cytoplasm. When X. borealis nuclei deprived of the envelope are injected into the cytoplasm of X. laevis oocytes, protein N] shifts from the grafted karyoplasm into the intact host nucleus. N 1 is reaccumulated less efficiently, if the host nuclear envelope is punctured. Puncturing of the nuclear envelope leeds to diffusion of nuclear protein antigens into the cytoplasm. This shows that an intact nuclear envelope is essential for the accumulation and retention of proteins in the oocyte nucleus. 120S