Hox genes in brachiopods and priapulids and protostome evolution

  title={Hox genes in brachiopods and priapulids and protostome evolution},
  author={Renaud de Rosa and Jennifer K. Grenier and Tatiana Andreeva and Charles E. Cook and Andr{\'e} Adoutte and Michael E Akam and Sean B. Carroll and Guillaume Balavoine},
Understanding the early evolution of animal body plans requires knowledge both of metazoan phylogeny and of the genetic and developmental changes involved in the emergence of particular forms. Recent 18S ribosomal RNA phylogenies suggest a three-branched tree for the Bilateria comprising the deuterostomes and two great protostome clades, the lophotrochozoans and ecdysozoans. Here, we show that the complement of Hox genes in critical protostome phyla reflects these phylogenetic relationships and… 

Hox genes from the Polystomatidae (Platyhelminthes, Monogenea).

Rotiferan Hox genes give new insights into the evolution of metazoan bodyplans

The expression of five Hox genes are reported during embryogenesis of the rotifer Brachionus manjavacas and it is shown how these genes define different functional components of the nervous system and not the usual bilaterian staggered expression along the anteroposterior axis.

Hox genes in the antarctic polyplacophoran Nuttallochiton mirandus.

Comparison with the results obtained in other molluscs seems to confirm the conservation of Hox genes in this phylum in terms of both presence and characteristics.


It is suggested that some of the anterior or posterior cognates have been lost in some lineages, most notably in Caudofoveata, while the medial cognates showed both losses and duplications.

Hox and ParaHox Genes in Flatworms: Characterization and Expression1

Flatworm Hox sequences and 18S rDNA sequence data support clear affinities of Platyhelminthes to spiralian lophotrochozoans, and Expression of Hox genes in intact and regenerating adult organisms show nested patterns with graded anterior expression boundaries, or ubiquitous expression.

Hox, ParaHox, ProtoHox: facts and guesses

Opposition views are discussed and it is proposed that the ProtoHox cluster had only two genes, and not four as commonly believed, which may help critical discussion of the evolution of the Hox/ParaHox family in the metazoan kingdom.

An Overview of Hox Genes in Lophotrochozoa: Evolution and Functionality

The data presented here suggest that at least nine genes were present while two other genes, Lox4 and Post-2, may either have been present in the ancestor or may have arisen as a result of duplication in the Brachiopoda-Mollusca-Annelida lineage.

Combined-method phylogenetic analysis of Hox and ParaHox genes of the metazoa.

ParaHox hypothesis is supported and first confirmation that ind (intermediate neuroblasts defective) is an anterior ParaHox ortholog from protostomes is given, as phylogenetic methods are used to determine Hox-gene orthologies and to infer probable clustering events leading to the current bilaterian Hox complement.



Homeobox genes in the ribbonworm Lineus sanguineus: evolutionary implications.

The isolation and identification of Hox genes in Lineus sanguineus is presented and it is found that the Lineus genome contains a single cluster of at least six H Cox genes: two anterior- class genes, three middle-class genes, and one posterior-class gene.

Archetypal organization of the amphioxus Hox gene cluster

The amphioxus genome has only one Hox gene cluster, and contains homologues of at least the first ten paralogous groups of vertebrate Hox genes in a collinear array, compatible with that inferred for a direct ancestor of the vertebrates.

Are Platyhelminthes Coelomates without a Coelom? An Argument Based on the Evolution of Hox Genes'

Arguments from 18S rDNA and Hox gene evolution are reviewed in favor of a late emergence of at least the rhabditophoran platyhelminths and flatworms can be convincingly grouped with the spiralian coelomate protostomes.

Hox genes and chordate evolution.

It is suggested that the simultaneous duplication of many classes of genes, often interacting in gene networks, allowed the elaboration of new developmental control mechanisms at vertebrate origins.

The Antennapedia-type homeobox genes have evolved from three precursors separated early in metazoan evolution.

The comparative analysis of the homeobox sequences reveals the subdivision of the Antennapedia-type homeobbox genes into three classes early in metazoan evolution, which suggests an important function of these genes even in the most primitive metazoans.

A PCR-based survey of homeobox genes in Ctenodrilus serratus (Annelida: Polychaeta).

The results are consistent with a hypothesis of a single HOM/HOX cluster in Ctenodrilus as extensive as that seen in strongly tagmatized arthropods, suggesting that the primitive role of these genes even in overtly metameric animals was something other than specification of overt segmental differentiation.

Organization of an echinoderm Hox gene cluster.

The Strongylocentrotus purpuratus genome contains a single ten-gene Hox complex >0.5 megabase in length. This complex was isolated on overlapping bacterial artificial chromosome and P1 artificial