William F. Loomis
Department of Biology
University of California, San Diego
La Jolla, Calif.

" Basic fibroblast growth factor (bFGF), a 155 amino acid protein found in Xenopus eggs, induces mesodermal differentiation. It may be brought into play during gastrulation by the product of the Vg-1 gene that is localized at the vegetal pole.

D. Kimmelman, J.A. Abraham, T. Haaparanta, T.M. Palisi, M. Kirschner, "The presence of fibroblast growth factor in the frog egg: Its role as a natural mesoderm inducer," Science, 242 (4881), 1053-6, 18 November 1988.

" Comparison of the sequences of an ancient gene has shown that two archaebacteria differ from each other as much as they differ from eubacteria. It appears that many lines of bacteria have evolved independently for billions of years.

N. Souillard, M. Magot, O. Possot, L. Sibold, "Nucleotide sequence of regions homologous to nifH (Nitrogenase Fe protein) from nitrogen-fixing archaebacteria Methanococcus...

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