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Xenopus laevis
Jake Nieb Developmental Biology
April 15, 2014
Background and History • African clawed frog • “Xeno” – strange; “pus” – foot • “laevis” – smooth • 1930s – first brought to the
United States and used as a low-cost pregnancy test [6]
– Lancelot Hogben (comparative endocrinologist)
– Urine injected into female hind leg, chorionic gonadotropin causes Xenopus to lay eggs [3]
• Pieter D. Nieuwkoop – used series of experiments to show benefits of Xenopus as a model organism [3]
Classification and Genetic Information
• Vertebrate
• Deuterostome (“mouth second”)
• Life cycle: approximately 12 months [6]
• Brood size: 300-1000 eggs [6]
• Genome: 3.1 × 109 bp; 18 chromosomes; allotetraploid (four sets of chromosomes) [6]
– Genome is structurally similar to humans
Related Species and Habitat
• Closely related to Xenopus tropicalis[2]
• Sub-Saharan Africa[4]
• Aquatic [6]
Advantages • Eggs
– Large and Robust – Ability to induce regardless of season
(chorionic gonadotropin) [3]
• Fertilization – External, easy to visualize and
manipulate [4]
• Embryos – Respond well to surgical procedures [5]
Advantages • Responds well to gain-of-
function experiments[4]
• Interactive fate maps available at xenbase (less detailed) [6]
• Fate map from 32-cell stage published in 1987 [1]
• Genome is sequenced [6]
• Effective technical approaches: – Morpholinos, RNAi,
transgenic chimeras [4]
– Nuclear transplants and cloning [2]
Disadvantages • Tetraploidy
– Loss of function mutations are difficult to implement [2]
• Comparison to X. tropicalis – Diploid, much more
useful for loss-of-function mutations [2]
– Shorter life cycle [6]
– Larger brood size [6]
• Only somewhat related to humans, less pertinent than mammalian model organisms [2]
Fun Facts • First cloned vertebrate
(1958) – genomic equivalence [2]
• Males lack vocal cords – mating “call” is actually muscle contractions – Acceptance call or
Rejection call [7]
• Populations in California, Virginia, and Delaware are overtaking native wildlife [7]
• They were originally injected with women’s urine! [3]
References • [1] Dale, L; Slack, J. 1987. Fate map for the 32-cell stage of Xenopus laevis. Development.
99:527-551.
• [2] Grainger, R. 2012. Xenopus tropicalis as a model organism for genetics and genomics: past, present and future. Methods in Molecular Biology. 917:3-15.
• [3] Gurdon, J; Hopwood, N. 2000. The introduction of Xenopus laevis into developmental biology: of empire, pregnancy testing and ribosomal genes. Journal of Developmental Biology. 44:43-50.
• [4] Harland, R; Grainger, R. 2011. Xenopus research: metamorphosed by genetics and genomics. Trends in Genetics. 27(12):507-515.
• [5] Hellsten, U; Harland, R; Gilchrist, M; Hendrix, D; Jurka, J; Kapitonov, V; Ovcharenko, I; Putnam, N; Shu, S; Taher, L; Blitz, I; Blumberg, B; Dichmann, D; Dubchak, I; Amaya, E; Detter, J; Fletcher, R; Gerhard, D; Goodstein, D; Graves, T; Grigoriev, I; Grimwood, J; Kawashima, T; Lindquist, E; Lucas, S; Mead, P; Mitros, T; Ogino, H; Ohta, Y; Poliakov, A; Pollet, N; Robert, J; Salamov, A; Sater, A; Schmutz, J; Terry, A; Vize, P; Warren, W; Wells, D; Wills, A; Wilson, R; Zimmerman, L; Zorn, A; Grainger, R; Grammer, T; Khokha, M; Richardson, P; Rokhsar, D. 2010. The genome of the western clawed frog Xenopus tropicalis. Science. 328:633-636.
• [6] Xenbase. 2014. National Institute of Child Health and Human Development.
• [7] Xenopus laevis – the African Clawed Frog. 2014. Smithsonian National Zoological Park.
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