engleski

Monophyly of Metazoa: Sponges as living fossils

Sequence alignments and construction of a phylogenetic tree from the catalytic domains revealed that the hexactinellid habdocalyptus dawsoni branches off first among the metazoan sequences ; the other two classes of the Porifera, The Calcarea (the sequence from Sycon raphanus was used) and the Demospongiae (the sequence from Geodia cydonium and Suberites domuncula were used) branch off later. his finding was also confirmed by comparing the regulatory part of the kinase gene. These data suggest that (i) within the phylum Porifera, the class Hexactinellida diverged first from the common ancestor to the Calcarea and the Demospongiae, which both appeared later, and (ii) the higher invertebrates are more closely related to the calcareous sponges. It is concluded that systematic analysis of genes, cDNAs and their deduced protein sequences from sponges allow an experimental approach to reflect upon the molecular events that occured during the transition from Protozoa to Metazoa.

monophyly; metazoa; fossils; cDNA

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