Oscillation of Inositol Polyphosphates in the Embryonic Cleavage Cycle of the Xenopus laevis

1995 ◽  
Vol 206 (2) ◽  
pp. 775-780 ◽  
Author(s):  
J.K. Han
1983 ◽  
Vol 64 (1) ◽  
pp. 147-162 ◽  
Author(s):  
A. Shinagawa

Non-nucleate fragments of animal eggs are known to show a cyclic change in rigidity similar to the change observed in the cleavage of normal eggs. The interval of cyclic change was compared with that of the cleavage cycle in Xenopus eggs. Procedures employed by both Hara and co-workers and Sakai & Kubota to obtain non-nucleate fragments were carefully repeated. Non-nucleate fragments produced by either of those procedures had a longer duration of cycle than the normal cleavage cycle (about 30%). By injection of colchicine or vinblastine the cycle of the nucleate fragment was lengthened to coincide with that of the non-nucleate partner. It is suggested that the basic cycle length intrinsic to egg cytoplasm is modulated by assembly-disassembly of the mitotic apparatus, as demonstrated by Sluder in the chromosome cycle of sea urchin eggs.


Author(s):  
Darcy B. Kelley ◽  
Martha L. Tobias ◽  
Mark Ellisman

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.


1956 ◽  
Vol 23 (3) ◽  
pp. 265-273 ◽  
Author(s):  
A. C. J. Burgers ◽  
G. J. van Oordt

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