BsSODF and BsSODR amplified a sequence of 322 bp, similar to Cu/Zn SOD from other deuterostomes
had a common ancestor, and we think that is what we are looking at here.
The NK cluster in the last common ancestor to protostomes and deuterostomes
probably contained a cluster of nine NK genes: Msx, NKl/slouch, NK3/bagpipe, NK4/tinman, Tlx/cl5, NK7, NK6/hgtx, NK5/Hmx, and Lbxl ladybird genes (Holland 2001, Garcia-Fernandez 2005, Larroux et al.
Although PPAR has not been described outside deuterostomes
, RXR is ubiquitous within metazoans.
The former belongs to the deuterostomes
and the latter to the protostomes, respectively.
The chordates (that include vertebrates), hemichordates (that include the living "acorn worms"), and echinoderms (that include the living starfish and echinoids) are all deuterostomes
and have the same pattern of early embryo development.
All species within the phylum Xenacoelomorpha appear to have lost almost all features that define them as deuterostomes
implying a history of extreme evolutionary simplification and loss.
Most animal phyla belong to one of two groups of bilaterians: the protostomes or deuterostomes
From the basic bilaterian plan, two developmental groups of organisms evolved namely deuterostomes
(echinoderms and chordates) and the protostones (almost everything else).
For example, humans are included in the following nested clades (using the informal names): eukaryotes, animals, deuterostomes
, vertebrates, gnathostomes, tetrapods, amniotes, mammals, eutherians, primates, monkeys, apes, and great apes (see Dawkins, 2004 for more information on the ancestry of humans).
Could it be that the ancestor of the deuterostomes
was a bottom-feeding dweller in the dark?
Despite the geographic and chronological distance, both sites have some genera in common and were dominated by arthropods; differing mainly in the rarity of deuterostomes
(a chordate and a crinoid have been found recently, H.