Why is Xenopus used for early embryonic cell cycle?
Cycling extracts derived from parthenogenetically activated Xenopus eggs exhibit rapid and sustained oscillations of CDK1 activity, and provide a useful tool to study the dynamical behaviors of this enzyme and others within the frog early embryonic oscillatory system (Murray 1991).
What is the earliest stage of embryonic development?
The early stages of embryonic development begin with fertilization. The process of fertilization is tightly controlled to ensure that only one sperm fuses with one egg. After fertilization, the zygote undergoes cleavage to form the blastula.
What is early development of frog?
During embryonic development, the egg will be converted into a tadpole containing millions of cells but containing the same amount of organic matter. The upper hemisphere of the egg — the animal pole — is dark. When deposited in the water and ready for fertilization, the haploid egg is at metaphase of meiosis II.
At what stage of the cell cycle is the cyclin component of MPF destroyed?
In addition to driving the events of M phase, MPF also triggers its own destruction by activating the anaphase-promoting complex/cyclosome (APC/C), a protein complex that causes M cyclins to be destroyed starting in anaphase.
What type of egg does Xenopus have?
Two species of Xenopus are regularly used by biologists, Xenopus laevis and Xenopus tropicalis. Both species are fully aquatic, and are easy to maintain in captivity. Frog eggs are large (~1.2mm diameter), produced in large quantities, and easy to manipulate.
Why is Xenopus a good model system to study development?
Because the Xenopus embryos develop outside of the body they can easily be surgically manipulated or treated with proteins and chemicals that interfere with development. Genetically, Xenopus are very similar to humans and are therefore a good model for human disease.
What are frog eggs?
Eggs. This is an egg mass laid by a frog. Each of those black dots is made up of a bunch of cells that will eventually grow into a tadpole. Depending on the species, these egg masses can be made up of several hundred eggs!
Where are frog eggs produced?
fresh water
The breeding behaviour is one of the most distinctive attributes of the Anura. Because the eggs can develop only under moist conditions, most frogs place their eggs in bodies of fresh water. Many species congregate in large numbers at temporary pools for short breeding seasons.
What happens to the Xenopus embryo after fertilization?
After fertilization, Xenopus embryos undergo cell cycles that have characteristic features ( Fig. 1 ). During the first, 90-minute cell cycle, cortical cytoplasmic movements and male and female pronuclear fusion occur.
Where is the blastocoel located in the Xenopus embryo?
The blastula stage embryo is a ball of cells surrounding a fluid filled cavity, the blastocoel, which is displaced to the animal hemisphere by the large, yolk rich, vegetal blastomeres. Fate maps have shown that the animal hemisphere will form the ectoderm, while the vegetal hemisphere will form the endoderm.
Where is the nucleus located in the Xenopus egg?
The Xenopusegg possesses a distinct polarity even before it is fertilized, with a darkly pigmented animal hemisphere and a lightly pigmented vegetal hemisphere. Within the egg the yolk is mainly confined to the vegetal hemisphere, while the nucleus is located close to the animal pole.
Where is Vg1 found in the early embryo?
Vg1 mRNA becomes enriched in the dorsal vegetal quadrant of the early embryo compared with the ventral vegetal quadrant ( Birsoy et al., 2006; Tao et al., 2005b ). Thus,several distinct mechanisms of partitioning probably exist. Fig. 1. Characteristics of Xenopus laevis early development.