A Developmental Basis for the Cambrian Radiation

Freeman, G. L.

doi:10.2108/zsj.24.113

Cited by 13 publications

(20 citation statements)

References 25 publications

(39 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general, the developmental patterning and the cellular specification of the rhynchonelliform brachiopod T. transversa and P. harmeri appear to be more similar than the craniiform brachiopod N. anomala , with the exception of the timing of mesoderm specification and mesodermal patterning. Similar conclusions emerged from the previous comparative embryonic fate map studies conducted between brachiopods and phoronids [12, 74–77], According to these studies, phoronids, rhynchonelliform and linguliform brachiopods share identical fate maps, suggesting that the last common ancestor of brachiopods and phoronids likely shared an early molecular embryonic patterning similar to the extant rhynchonelliform brachiopods and phoronids.…”

Section: Discussionsupporting

confidence: 87%

“…Previous embryonic comparisons based on fate maps between a number of brachiopod species ( T. transversa, Hemithiris sp., Terebratulina sp. and N. anomala ) and phoronids ( Phoronis vancouverensis ), suggested differences in the timing of axis and regional specification [12, 74–77], For instance, in P. vancouverensis, T. transversa, Hemithiris sp. and Terebratulina sp., axis formation is related to the movement of cells along the dorsal side of the future anterior–posterior axis of the larva during late gastrulation, whilst in N. anomala the larval anterior–posterior axis corresponds to the animal-vegetal axis of the egg and that axis is set up already before the blastula stage [12, 74–77], Recent molecular data from T. transversa and N. anomala development also support the notion that an anterior-posterior molecular re-patterning of the blastopore occurs at the gastrula stage in T. transversa , which takes place before axial elongation, unlike in N.anomala , where such a symmetry-breaking event is absent [71].…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Molecular patterning during the development ofPhoronopsis harmerireveals similarities to rhynchonelliform brachiopods

Andrikou

Passamaneck

Lowe

et al. 2019

Preprint

View full text Add to dashboard Cite

Background Answering the question how conserved patterning systems are across evolutionary lineages requires a broad taxon sampling. Phoronid development has previously been studied using fate mapping and morphogenesis, yet molecular descriptions are missing. Here we report the expression patterns of the evolutionarily conserved anterior (otx, gsc, six3/6, nk2.1), posterior (cdx, bra) and endomesodermal (foxA, gata4/5/6, twist) markers in the phoronid Phoronopsis harmeri. Results The transcription factors foxA, gata4/5/6 and cdx show conserved expression in patterning the development and regionalization of the phoronid embryonic gut, with foxA expressed in the presumptive foregut, gata4/5/6 demarcating the midgut and cdx confined to the hindgut. Surprisingly, brachyury, an evolutionary conserved transcription factor often associated with gastrulation movements and patterning of the mouth and hindgut, seems to be unrelated with gastrulation and mouth patterning in phoronids. Furthermore, six3/6, a well-conserved anterior marker, shows a remarkably dynamic expression, demarcating not only the apical organ and the oral ectoderm, but also clusters of cells of the developing midgut and the anterior mesoderm, similar to what has been reported for brachiopods, bryozoans and some deuterostome Bilateria. Conclusions Our comparison of gene expression patterns with other studied Bilateria reveals that the timing of axis determination and cell fate distribution of the phoronid shows highest similarities to rhynchonelliform brachiopods. Despite these similarities, the phoronid P. harmeri shows also particularities in its development, which hint to divergences in the arrangement of gene regulatory networks responsible for germ layer formation and axis specification.

show abstract

Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Molecular patterning during the development ofPhoronopsis harmerireveals similarities to rhynchonelliform brachiopods

Andrikou

Passamaneck

Lowe

et al. 2019

Preprint

View full text Add to dashboard Cite

show abstract

“…The only posterior Hox gene present in N. anomala, post2, could not be amplified in cDNA obtained from mixed embryonic and larval stages, suggesting that it is not expressed -or at least expressed at really low levels-during these stages of the life cycle. The absence of larval expression of Lox4 and post2 could be related to the lack of the pedicle lobe of craniiform brachiopod larva, which is a characteristics of the lineage [65,66].…”

Section: Posterior Hox Genesmentioning

confidence: 99%

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

Schiemann

Martín-Durán

Børve

et al. 2016

Preprint

View full text Add to dashboard Cite

Hox genes are often clustered in animal genomes and exhibit spatial and/or temporal collinearity. It is generally believed that temporal collinearity is the major force preserving Hox clusters. However, studies combining genomic and gene expression analyses of Hox genes are scarce, particularly within Spiralia and Lophotrochozoa (e.g. mollusks, segmented worms, and flatworms). Here, we use two brachiopod species -Terebratalia transversa and Novocrania anomala-that respectively belong to the two major brachiopod lineages to characterize their Hox complement, the presence of a Hox cluster, and the temporal and spatial expression of their Hox genes.We demonstrate that the Hox complement consists of ten Hox genes in T. transversa (lab, pb, Hox3, dfd, scr, lox5, antp, lox4, post2 and post1) and nine in N. anomala (missing post1). Additionally, T. transversa has an ordered, split Hox cluster. Expression analyses reveal that Hox genes are neither temporally nor spatially collinear, and only the genes pb (in T. transversa), Hox3 and dfd (in both brachiopods) show staggered expression in the mesoderm. Remarkably, lab, scr, antp and post1 are associated with the development of the chaetae and shell-forming epithelium, as also observed in annelid chaetae and mollusk shell fields. This, together with the expression of Arx homeobox, supports the deep conservation of the molecular basis for chaetae formation and shell patterning in Lophotrochozoa. Our findings challenge the current evolutionary scenario that (temporal) collinearity is the major mechanism preserving Hox clusters, and suggest that Hox genes were involved in the evolution of lophotrochozoan novelties.

show abstract

“…The functional studies of the lineages have been pioneered by fi rst isolating blastomeres of the amphipod Parhyale (Extavour 2005 ) and second by ablating specifi c blastomeres and clones at will in the same species (Price et al 2010 ;Hannibal et al 2012 ). It can be argued that a comparison on the level of the different abilities to regulate early development can tell about ancestral features (Freeman 2007 ), but this is only possible if functional studies are available for a broad sample across the taxon of choice. So far, the crustaceans have only benefi tted from functional assessment by ablations in Parhyale (Price et al 2010 ;Hannibal et al 2012 ).…”

Section: Invariant Early Cell Lineagesmentioning

confidence: 99%