Faculty Opinions recommendation of Cephalopod Hox genes and the origin of morphological novelties.

2003 ◽  
Author(s):  
Alejandro Sanchez-Alvarado
Keyword(s):  
Hox Genes ◽  
Morphological Novelties

Cephalopod Hox genes and the origin of morphological novelties

Nature ◽  
2003 ◽  
Vol 424 (6952) ◽  
pp. 1061-1065 ◽  
Author(s):  
Patricia N. Lee ◽  
Patrick Callaerts ◽  
Heinz G. de Couet ◽  
Mark Q. Martindale
Keyword(s):  
Hox Genes ◽  
Morphological Novelties

scholarly journals Non-collinear Hox gene expression in bivalves and the evolution of morphological novelties in mollusks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
David A. Salamanca-Díaz ◽  
Andrew D. Calcino ◽  
André L. de Oliveira ◽  
Andreas Wanninger
Keyword(s):  
Gene Expression ◽  
Morphological Traits ◽  
Hox Genes ◽  
Current Data ◽  
Phenotypic Traits ◽  
Parahox Gene ◽  
Hox Gene ◽  
Morphological Novelties ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

AbstractHox genes are key developmental regulators that are involved in establishing morphological features during animal ontogeny. They are commonly expressed along the anterior–posterior axis in a staggered, or collinear, fashion. In mollusks, the repertoire of body plans is widely diverse and current data suggest their involvement during development of landmark morphological traits in Conchifera, one of the two major lineages that comprises those taxa that originated from a uni-shelled ancestor (Monoplacophora, Gastropoda, Cephalopoda, Scaphopoda, Bivalvia). For most clades, and bivalves in particular, data on Hox gene expression throughout ontogeny are scarce. We thus investigated Hox expression during development of the quagga mussel, Dreissena rostriformis, to elucidate to which degree they might contribute to specific phenotypic traits as in other conchiferans. The Hox/ParaHox complement of Mollusca typically comprises 14 genes, 13 of which are present in bivalve genomes including Dreissena. We describe here expression of 9 Hox genes and the ParaHox gene Xlox during Dreissena development. Hox expression in Dreissena is first detected in the gastrula stage with widely overlapping expression domains of most genes. In the trochophore stage, Hox gene expression shifts towards more compact, largely mesodermal domains. Only few of these domains can be assigned to specific developing morphological structures such as Hox1 in the shell field and Xlox in the hindgut. We did not find traces of spatial or temporal staggered expression of Hox genes in Dreissena. Our data support the notion that Hox gene expression has been coopted independently, and to varying degrees, into lineage-specific structures in the respective conchiferan clades. The non-collinear mode of Hox expression in Dreissena might be a result of the low degree of body plan regionalization along the bivalve anterior–posterior axis as exemplified by the lack of key morphological traits such as a distinct head, cephalic tentacles, radula apparatus, and a simplified central nervous system.

scholarly journals The Evolution of Hox Genes in Spiralia

2021 ◽  
Author(s):  
Andreas Hejnol ◽  
Ludwik Gasiorowski ◽  
Jose-Maria Martin-Duran
Keyword(s):  
Hox Genes ◽  
Gene Organization ◽  
Body Parts ◽  
Regulatory Pathways ◽  
Hox Gene ◽  
Larval Stages ◽  
Life History Stages ◽  
Evolutionary Changes ◽  
Gene Expression Studies ◽  
Morphological Novelties

The decoding of genomes of a larger number of animal species have provided further insights into the genomic Hox gene organization and with this indicated the evolutionary changes during the radiation of several clades. The expansion of gene expression studies during development and life history stages of more species, complete the picture of the relationship between cluster organisation and temporal and spatial correlation of the Hox activity. Now these results open the opportunity to look deeper into the regulatory pathways that form these patterns and identify what exact changes caused the evolution of the application of this iconical gene set for the evolution of new larval forms and new structures. Here we review recent progress of Hox gene related research in the large clade Spiralia, that comprises Annelida, Mollusca, Lophophorata, Platyhelminthes, Nemertea and others. Albeit their relationship to each other is not resolved yet, there are emerging patterns that indicate that Hox genes are mainly used for patterning late, adult body parts and that Hox genes are often not expressed on the larval stages. Hox genes seem also often recruited for the formation of morphological novelties. Together with the emerging genomic information Hox genes show a much more dynamic evolutionary history than previously assumed.

scholarly journals Clustered brachiopod Hox genes are not expressed collinearly and are associated with lophotrochozoan novelties

2016 ◽  
Author(s):  
Sabrina M. Schiemann ◽  
José M. Martín-Durán ◽  
Aina Børve ◽  
Bruno C. Vellutini ◽  
Yale J. Passamaneck ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Expression Data ◽  
Molecular Basis ◽  
Hox Genes ◽  
Expression Data ◽  
Specific Expression ◽  
Spatial Expression ◽  
Morphological Novelties ◽  
Hox Clusters

AbstractTemporal collinearity is often regarded as the force preserving Hox clusters in vertebrate genomes. Studies that combine genomic and gene expression data in invertebrates would allow generalizing this observation across all animals, but are scarce, particularly within Lophotrochozoa (e.g., snails and segmented worms). Here, we use two brachiopod species –Terebratalia transversa, Novocrania anomala– to characterize the complement, cluster and expression of their Hox genes. T. transversa has an ordered, split cluster with ten genes (lab, pb, Hox3, dfd, scr, lox5, antp, lox4, post2, post1), while N. anomala has nine (missing post1). Our in situ hybridization, qPCR and stage specific transcriptomic analyses show that brachiopod Hox genes are neither strictly temporally nor spatially collinear; only pb (in T. transversa), Hox3 and dfd (in both brachiopods) show staggered mesodermal expression. The spatial expression of the Hox genes in both brachiopod species correlates with their morphology and demonstrates cooption of Hox genes in the chaetae and shell fields, two major lophotrochozoan morphological novelties. The shared and specific expression of a subset of Hox genes, Arx and Zic orthologs in chaetae and shell-fields between brachiopods, mollusks, and annelids supports the deep conservation of the molecular basis forming these lophotrochozoan hallmarks. Our findings challenge that collinearity alone preserves lophotrochozoan Hox clusters, indicating that additional genomic traits need to be considered in understanding Hox evolution.

scholarly journals Clustered brachiopod Hox genes are not expressed collinearly and are associated with lophotrochozoan novelties

2017 ◽  
Vol 114 (10) ◽  
pp. E1913-E1922 ◽  
Author(s):  
Sabrina M. Schiemann ◽  
José M. Martín-Durán ◽  
Aina Børve ◽  
Bruno C. Vellutini ◽  
Yale J. Passamaneck ◽  
...  
Keyword(s):  
Hox Genes ◽  
Notch Pathway ◽  
Gene Clusters ◽  
Molecular Evidence ◽  
Expression Data ◽  
Specific Expression ◽  
Real Time Quantitative Pcr ◽  
Morphological Novelties ◽  
Animal Genomes

Temporal collinearity is often considered the main force preserving Hox gene clusters in animal genomes. Studies that combine genomic and gene expression data are scarce, however, particularly in invertebrates like the Lophotrochozoa. As a result, the temporal collinearity hypothesis is currently built on poorly supported foundations. Here we characterize the complement, cluster, and expression of Hox genes in two brachiopod species,Terebratalia transversaandNovocrania anomala.T. transversahas a split cluster with 10 genes (lab,pb,Hox3,Dfd,Scr,Lox5,Antp,Lox4,Post2, andPost1), whereasN. anomalahas 9 genes (apparently missingPost1). Our in situ hybridization, real-time quantitative PCR, and stage-specific transcriptomic analyses show that brachiopod Hox genes are neither strictly temporally nor spatially collinear; onlypb(inT. transversa),Hox3(in both brachiopods), andDfd(in both brachiopods) show staggered mesodermal expression. Thus, our findings support the idea that temporal collinearity might contribute to keeping Hox genes clustered. Remarkably, expression of the Hox genes in both brachiopod species demonstrates cooption of Hox genes in the chaetae and shell fields, two major lophotrochozoan morphological novelties. The shared and specific expression of Hox genes, together withArx,Zic, and Notch pathway components in chaetae and shell fields in brachiopods, mollusks, and annelids provide molecular evidence supporting the conservation of the molecular basis for these lophotrochozoan hallmarks.

Additional Dermal Ossifications in the Anuran Skull: Morphological Novelties or Archaic Elements?

2011 ◽  
Vol 4 (1) ◽  
pp. 17-27 ◽  
Author(s):  
Sergei V. Smirnov
Keyword(s):  
Common Ancestor ◽  
The State ◽  
Cranial Morphology ◽  
Anterior Portion ◽  
Bombina Orientalis ◽  
Common Event ◽  
Rostral Portion ◽  
Morphological Novelties ◽  
Dermal Bones

Examination of the cranial morphology in Bombina orientalis (Anura: Discoglossidae) revealed the occurrence of additional dermal bones lying: a) between the nasals and frontoparietals, b) between frontoparietals, and c) on the tectum synoticum behind the frontoparietals. The presence of similar bones as well as extra ossifications lying in the midline in the rostral portion of skull was shown to be a rather common event among anurans. Based on the occurrence of bones with similar topology in crossopterygians and different stegocephalians, it was concluded that extra ossifications sporadically appearing in anurans are more likely to be ancient cranial elements than neomorphs. Additional dermal bones found in the anterior portion of the anuran skull are homologous to the postrostrals of crossopterygians; extra ossifications lying between the frontoparietals correspond to the bones with similar topology sporadically appearing in crossopterygians and stegocephalians; and extra bones situated behind the frontoparietals are homologous to the lateral extrascapulars (postparietals of stegocephalians) and the median extrascapular of crossopterygians. These extra bones were proposed to be inherited from the presumed common ancestor of all Gnathostomes and retained in anurans in the state of latent capacities. The sporadic appearance of these bones in anurans results from the phenotypical realization of these latent capacities.

Sign in / Sign up

Export Citation Format

Share Document