ISSN:
1432-1432
Keywords:
Xenopus tropicalis
;
Xenopus borealis
;
Globin cDNAs
;
Evolution
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary Globin mRNAs ofXenopus borealis andXenopus tropicalis have been cloned and sequenced. The nucleotide and derived amino acid sequences were compared with each other and with already available data fromXenopus laevis. This analysis rendered clear evidence that the common ancestor ofX. laevis andX. borealis, but not ofX. tropicalis, had lost one amino acid of the β-globins prior to a genome duplication event that preceded the segregation of the former two species. Replacement-site substitutions were used to calculate a rough time scale of genome duplication and species segregation. The results suggest an ancient separation between theX. laevis and theX. tropicalis groups occurring approximately 110–120 million years ago. Analysis of the amino acid chains demonstrated various alterations. However, some functional domains, like heme-binding sites andα1β2 contact sites, were subject to a high degree of conservation, indicating the existence of functional constraints on them also in the genusXenopus.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02115578
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