Inhibition of protein synthesis elicits early grey crescent formation in the axolotl oocyte

1983 ◽  
Vol 192 (3-4) ◽  
pp. 196-199 ◽  
Author(s):  
Jean Gautier ◽  
Jean-Claude Beetschen
Keyword(s):  
Protein Synthesis ◽  
Crescent Formation ◽  
Grey Crescent ◽  
Inhibition Of Protein Synthesis

Heat-shock-induced grey crescent formation in axolotl eggs and oocytes: the role of gravity

Development ◽  
1987 ◽  
Vol 100 (4) ◽  
pp. 599-609
Author(s):  
J.-C. Beetschen ◽  
J. Gautier
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Synergistic Action ◽  
Nuclear Factor ◽  
Crescent Formation ◽  
Animal Pole ◽  
Grey Crescent ◽  
Cytoskeletal Structure

Axolotl eggs were heat shocked (36.8°C, 10min) inside their jelly layers. Heat shock (HS) was shown to induce the precocious appearance of a grey crescent (GC) in a number of eggs immediately after fertilization (Benford & Namenwirth, 1974). It was also demonstrated that this phenomenon occurs in fertilized or artificially activated eggs only when they are shocked within 11/2h after spawning. The GC forms still later in heated unfertilized, nonactivated eggs. The role of the jelly layers is considered to be mechanical: a proportion of eggs is maintained in a tilted position until the egg is able to orient animal pole upwards under the influence of gravity as a late consequence of activation. The jelly layers are not essential if the eggs are artificially tilted or rotated during HS. GC formation can also be induced in in vitro maturing oocytes, provided they are tilted during HS. Gravity thus plays an essential role in the cytoplasmic rearrangements leading to HS-induced GC formation. Our results indicate a synergistic action between heat and gravity in this process. The cytological appearance of the GC formed in those experiments is that of a ‘Born's crescent’ with a conspicuous ‘vitelline wall’ (Pasteels, 1964). When oocytes are enucleated before maturation, HS has no effect on GC formation. A nuclear factor is therefore essential, as has been demonstrated in early GC formation induced by inhibitors of protein synthesis. Finally, incorporation of amino acids into oocyte proteins appears to be rapidly inhibited by HS (from 5 min). However, we cannot conclude that GC formation is in fact triggered by inhibition of protein synthesis. It is also likely that HS disrupts cytoskeletal structure, hence facilitating cytoplasmic rearrangements. Nevertheless, these results are in agreement with the scheme we recently proposed for GC formation in the rotated axolotl oocyte (Gautier & Beetschen, 1985).

Selective Inhibition of Cleavage in Different Regions of the Frog Egg by Sulphydryl Inhibitors

Development ◽  
1956 ◽  
Vol 4 (1) ◽  
pp. 73-92
Author(s):  
Lucena J. Barth
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Total Nitrogen ◽  
Selective Inhibition ◽  
Inorganic Materials ◽  
Crescent Formation ◽  
Animal Pole ◽  
Grey Crescent ◽  
Histochemical Methods ◽  
Small Spot

That the materials for protein synthesis in the frog egg must come from yolk is indicated by the constancy of total nitrogen during development (Gregg & Ballentine, 1946) and the fact that the egg can develop with no outside source of organic or inorganic materials. When and where in the developing egg new proteins arise, and what are the mechanisms which control the rate and direct the specificity of such syntheses, are problems which are beginning to occupy increasing numbers investigators using several methods of attack—immunological, enzymological, electrophoretic, and incorporation of labelled amino acids, for example. Brachet (1940), using histochemical methods, described a change in the distribution of sulphydryl proteins coincident with grey crescent formation. In the newly-laid egg of Triton or Pleurodeles Brachet found the sulphydryl proteins to be restricted to a small spot centred about the maturation figure near the animal pole. This picture changed during the first few hours after fertilization.

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