The four new laboratory sequences (Mga lab, Oed lab, Sma lab, and Vpu lab) presented three residues that are characteristic of PG-1 proteins in deuterostomes and protostomes
, Ala29, Asn41, and Thr43 (Fig.
Likewise, deuterostomes have their heart on the ventral side, while protostomes
have it on the dorsal side.
In N-linked saccharide chains of species belonging to protostomes
(nematode, squid, and limpets, etc.
However, nemerteans, or "ribbon worms," belong to their own phylum of about 1300 species in the lophotrochozoan clade of protostomes
that includes molluscs and annelids, whereas nematodes and related invertebrates such as arthropods constitute separate phyla of ecdysozoan protostomes
(Kajihara et al.
The same collagen-proteoglycan-adhesive glycoprotein ECM is found in both protostomes
Testing the new animal phylogeny: first use of combined large-subunit and small-subunit rRNA gene sequences to classify the protostomes
Finally, we examined representative metazoan genomes and found highly conserved usherin genes throughout the deuterostome lineage as well as in some protostomes
Based on the lack of homology between the postoral ciliated bands and on recent phylogenies of protostomes
and polychaetes, a broader definition of trochophore is more likely to reflect the plesi-omorphic condition: a larva with a preoral ciliated band derived from trochoblasts (prototroch) (Damen and Dictus, 1994; Rouse, 1999; Maslakova et al.
The initial interest in characterizing hunchback (hb) gene products in protostomes
arose from Hb's role as a gap-class segmentation gene in anteroposterior (AP) patterning in dipteran embryos (Lehman and Nusslein-Volhard, 1987; Tautz et al.
So the main question is this: Are the trochophora and dipleurula larvae ancestral to protostomes
and deuterostomes (or perhaps ambulacrarians), respectively, or have these larval types evolved convergently in several clades?
Sexual maturation was shunted to the terminal benthic stage, but the swimming, feeding trochophore and dipleurula were retained as the larval form of protostomes
and deuterostomes, respectively.
18S rRNA suggests that Entoprocta are protostomes
, unrelated to Ectoprocta.