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J Wattel

Publications and source records attributed to J Wattel.

4 recordsLinked to original sources
PubMed1997

alpha-Crystallin sequences support a galliform/anseriform clade.

An unresolved issue in higher avian systematics is the position of the fowl-like and the duck-like birds, Galliformes and Anseriformes, respectively. Most studies place these orders at the base of the neognath radiation. While DNA hybridization data support a sister-group relationship of Galliformes and Anseriformes, macromolecular sequence analyses have not yet been able to provide a clear-cut answer. In this study, we present nucleotide sequences coding for the eye lens proteins alpha A- and alpha B-crystallin of a palaeognath, a galliform, an anseriform, and two other neognathous birds. Phylogenetic analyses of this data set clearly support a galliform/anseriform clade, to the exclusion of other neognaths.

Animals↗
PubMed1996

Protein sequences indicate that turtles branched off from the amniote tree after mammals.

The phylogenetic relationships among the major groups of amniote vertebrates remain a matter of controversy. Various alternatives for the position of the turtles have been proposed, branching off either before or after the mammals. To discover the phylogenetic position of turtles in relation to mammals and birds, we have determined cDNA sequences for the eye lens proteins alpha A- and alpha B-crystallin of the red-eared slider turtle (Trachemys scripta elegans). In addition, databases were searched for turtle protein sequences, for which mammalian, avian, and outgroup orthologs were available. All sequences were analyzed by three phylogenetic tree reconstruction methods (neighbor-joining, maximum parsimony, and maximum likelihood). Including the alpha-crystallins, 7 out of 12 proteins support a sister-group relation of turtles and birds with all 3 methods. For each of the other five proteins no topology was consistently preferred by the three approaches. Analyses of the combined amino acid data (1,695 aligned sites) also give extremely strong evidence that turtles are nearer to birds, indicating that mammals branched off before the divergence between turtles and birds occurred.

Animals↗
PubMedDate not supplied

Ratites as oldest offshoot of avian stem--evidence from alpha-crystallin A sequences.

One of the most disputed issues in avian phylogeny is the origin of the ratites, the large flightless birds of the Southern Hemisphere (reviewed in refs 1-3). It is still not generally agreed whether the ostriches, rheas, emus and cassowaries, and probably kiwis, form a natural, monophyletic group, although much recent evidence supports this view. Also, their phylogenetic relationship with the other avian orders remains unresolved, comparative protein sequence studies might shed new light on this problem. Therefore, we determined the amino acid sequence of the eye lens protein alpha-crystallin A in ostrich, rhea and emu, and in representatives of 13 other avian orders. Comparison of these sequences with known alpha A sequences of mammals, reptiles, frog and dogfish provides strong evidence that the ratites, as a monophyletic assemblage, represent the first offshoot of the avain line.

Amino Acid Sequence↗