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Updated: Sep 9, 2026
Manipulation and In Vitro Maturation of Xenopus laevis Oocytes, Followed by Intracytoplasmic Sperm Injection, to Study Embryonic Development
Published on: February 9, 2015
Effect of microinjection of rap 2A point mutant proteins on maturation and mottling in Xenopus oocytes
1Instituto de Investigaciones Biomédicas, CSIC, Universidad Autónoma de Madrid, Spain.
Abstract:
We have analyzed the morphological alterations induced in Xenopus oocytes as a consequence of the microinjection of rap 2A proteins with point mutations at critical positions in the functional domains defined for members of the ras superfamily. Ala 35 rap 2A, a point mutation in the "effector" domain, is able to induce the rearrangement of the pigments in the animal hemisphere termed "mottling". This characteristic phenotype is delayed in asn 17 rap 2A and wild-type rap 2A proteins. A completely different phenotype appears as a consequence of the microinjection of Val 12-rap 2A. This mutant is able to trigger oocyte maturation and is less efficient inducing mottling than Ala 35 or wild-type rap 2A proteins. Neither of these rap 2A mutant proteins is able to counteract ras-induced maturation. However there is a striking interference with progesterone-induced maturation, since wild-type or val 12 rap 2A microinjection reduced the viability of progesterone-treated oocytes. These findings suggest that rap2A proteins are regulatory elements in distinct signal transduction pathways that either lead to the morphological changes associated with the phenotype "mottling" or to oocyte maturation.
Insights
Mutant rap 2A proteins induce distinct Xenopus oocyte changes. Specific mutations affect pigment mottling and oocyte maturation, revealing rap2A
Area of Science:
- Cell Biology
- Developmental Biology
- Molecular Biology
Background:
- Ras superfamily proteins regulate crucial cellular processes.
- Rap2A is a member of the Ras superfamily with incompletely understood functions.
- Xenopus oocytes are a valuable model for studying signal transduction pathways.
Purpose of the Study:
- To investigate the functional roles of rap2A proteins in Xenopus oocytes.
- To analyze the effects of specific rap2A mutations on oocyte morphology and maturation.
- To elucidate the involvement of rap2A in distinct signaling pathways.
Main Methods:
- Microinjection of wild-type and mutant rap2A proteins into Xenopus oocytes.
- Observation and analysis of induced morphological alterations, including pigment mottling.
- Assessment of oocyte maturation triggered by rap2A proteins and progesterone.
- Evaluation of interference with ras-induced and progesterone-induced maturation.
Main Results:
- Ala 35 rap2A induced pigment mottling in the animal hemisphere.
- Asn 17 rap2A and wild-type rap2A showed delayed mottling.
- Val 12 rap2A triggered oocyte maturation but was less efficient in inducing mottling.
- Rap2A mutants did not counteract ras-induced maturation but interfered with progesterone-induced maturation, reducing oocyte viability.
Conclusions:
- Rap2A proteins act as regulatory elements in distinct signal transduction pathways.
- Specific rap2A mutations lead to differential effects on oocyte morphology (mottling) and maturation.
- Rap2A signaling pathways are involved in regulating both pigment rearrangement and the oocyte maturation process.
