Cloning of ascidian homeobox genes provides evidence for a primordial chordate cluster

Gregorio, Anna Di; Spagnuolo, Antonietta; Ristoratore, Filomena; Pischetola, M.; Aniello, Francesco; Branno, Margherita; Cariello, Lucio; Lauro, Roberto Di

doi:10.1016/0378-1119(95)00035-5

Cited by 92 publications

(48 citation statements)

References 23 publications

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“…2 a-c) whose members possess prominent body wall outgrowths. These include the urochordates, in which two Dll͞Dlx genes have been identified (15), and the echinoderms. Within the urochordates, the tunicates or ascidians possess a free-swimming larval form that metamorphoses into a sessile adult.…”

Section: Resultsmentioning

confidence: 99%

The origin and evolution of animal appendages

Panganiban

Irvine

Lowe

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

399

270

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Animals have evolved diverse appendages adapted for locomotion, feeding and other functions. The genetics underlying appendage formation are best understood in insects and vertebrates. The expression of the Distal-less (Dll) homeoprotein during arthropod limb outgrowth and of Dll orthologs (Dlx) in fish fin and tetrapod limb buds led us to examine whether expression of this regulatory gene may be a general feature of appendage formation in protostomes and deuterostomes. We find that Dll is expressed along the proximodistal axis of developing polychaete annelid parapodia, onychophoran lobopodia, ascidian ampullae, and even echinoderm tube feet. Dll͞Dlx expression in such diverse appendages in these six coelomate phyla could be convergent, but this would have required the independent co-option of Dll͞Dlx several times in evolution. It appears more likely that ectodermal Dll͞Dlx expression along proximodistal axes originated once in a common ancestor and has been used subsequently to pattern body wall outgrowths in a variety of organisms. We suggest that this pre-Cambrian ancestor of most protostomes and the deuterostomes possessed elements of the genetic machinery for and may have even borne appendages.

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Section: Resultsmentioning

confidence: 99%

The origin and evolution of animal appendages

Panganiban

Irvine

Lowe

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

399

270

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“…There are nine Hox genes in the C. intestinalis genome (76,77 ). The Ciona Hox genes are located on five different scaffolds containing Hox 1, Hox 2 to 4, Hox 5 and 6, Hox 10, and Hox 12 and 13.…”

Section: R E S E a R C H A R T I C L E Smentioning

confidence: 99%

The Draft Genome of Ciona intestinalis : Insights into Chordate and Vertebrate Origins

Dehal

Satou

Campbell

et al. 2002

Science

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1,529

1,169

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The first chordates appear in the fossil record at the time of the Cambrian explosion, nearly 550 million years ago. The modern ascidian tadpole represents a plausible approximation to these ancestral chordates. To illuminate the origins of chordate and vertebrates, we generated a draft of the protein-coding portion of the genome of the most studied ascidian, Ciona intestinalis. The Ciona genome contains ϳ16,000 protein-coding genes, similar to the number in other invertebrates, but only half that found in vertebrates. Vertebrate gene families are typically found in simplified form in Ciona, suggesting that ascidians contain the basic ancestral complement of genes involved in cell signaling and development. The ascidian genome has also acquired a number of lineage-specific innovations, including a group of genes engaged in cellulose metabolism that are related to those in bacteria and fungi.

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“…To date, nine Hox genes have been identified in the C. intestinalis genome, representing members of the anterior, medial, and posterior paralog groups and corresponding to a single Hox complex (Di Gregorio et al, 1995;Dehal et al, 2002;. C. intestinalis Hox genes do not appear to be arranged in a single cluster, although most members of the complex are linked (Dehal et al, 2002;Spagnuolo et al, 2003;Fig.…”

Section: Cnsmentioning

confidence: 99%

Ciona intestinalis: Chordate development made simple

2005

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Thanks to their transparent and rapidly developing mosaic embryos, ascidians (or sea squirts) have been a model system for embryological studies for over a century. Recently, ascidians have entered the postgenomic era, with the sequencing of the Ciona intestinalis genome and the accumulation of molecular resources that rival those available for fruit flies and mice. One strength of ascidians as a model system is their close similarity to vertebrates. Literature reporting molecular homologies between vertebrate and ascidian tissues has flourished over the past 15 years, since the first ascidian genes were cloned. However, it should not be forgotten that ascidians diverged from the lineage leading to vertebrates over 500 million years ago. Here, we review the main similarities and differences so far identified, at the molecular level, between ascidian and vertebrate tissues and discuss the evolution of the compact ascidian genome.

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Cloning of ascidian homeobox genes provides evidence for a primordial chordate cluster

Cited by 92 publications

References 23 publications

The origin and evolution of animal appendages

The origin and evolution of animal appendages

The Draft Genome of Ciona intestinalis : Insights into Chordate and Vertebrate Origins

Ciona intestinalis: Chordate development made simple

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