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Gynogenesis

Gynogenesis is a process where cell division is suppressed to increase the ploidy of the organism. In Xenopus, this can be a powerful technique to convert haploid organisms into a diploid organism. As a consequence, these animals are "instantly inbred" and can be screened for phenotypes quickly avoiding the generations of breeding necessary in a conventional screen. In addition, haploid embryos develop significant abnormalities as development proceeds precluding screening for phenotypes at late stages. By creating gynogenotes, the "haploid syndrome" can be avoided. Alternatively, gynogenesis can be a strategy for inbreeding lines quickly which can save time in making isogenic lines.

There are two gynogenetic strategies for Xenopus. By performing gynogenesis early to suppress polar body extrusion, loci near the centromere are made homozygous but not necessarily distal loci. Embryos tend to tolerate "early" gynogenesis better making it more efficient.

In the seoond strategy, the first mitotic cell cleavage is suppressed and all loci are made homozygous. In this manner, an isogenic line can be quickly created. However, suppression of first cell cleavage in "late" gynogenesis is not as well tolerated by the embryo making it less efficient than "early" gynogenesis.

Two techniques are availble to create gynogenotes. In the first, high pressure is used to prevent cell division. This technique requires specialized equipment to create extremely high pressures and is not presented here. For more information on high pressure gynogenesis contact Robert Grainger or Lyle Zimmerman.

The second technique was developed in the Grainger lab and uses cold shock. Cold shock is easy to use and effective.

Grainger Lab Protocols for Gynogenesis

Early Cold Shock (HTML or download PDF)

Late Cold Shock (HTML or download PDF)