The Amphioxus <i>SoxB</i> Family: Implications for the Evolution of Vertebrate Placodes

Meulemans, Daniel; Bronner‐Fraser, Marianne

doi:10.7150/ijbs.3.356

Cited by 67 publications

(68 citation statements)

References 66 publications

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“…However, the proposed placode generates neither neuroendocrine cells that give rise to GnRH neurons nor endocrine cells that give rise to adenohypophyseal endocrine cells. Thus, the first chordate may have lacked placodes (Meulemans and Bronner-Fraser, 2007). These observations provide support the clade Olfactores.…”

Section: Formation Of Peripheral Nervous Systemsupporting

confidence: 64%

Formation of Nervous Systems and Neural Stem Cells in Ascidians

Terakado¹

2012

Neural Stem Cells and Therapy

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Section: Formation Of Peripheral Nervous Systemsupporting

confidence: 64%

Formation of Nervous Systems and Neural Stem Cells in Ascidians

Terakado¹

2012

Neural Stem Cells and Therapy

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“…In the sea urchin Strongylocentrotus purpuratus and the urochordate Ciona intestinalis, only a single SoxB1 gene is present. Amphioxus as a primitive cephalochordate has three SoxB1 genes and a single SoxB2 gene [26]. The first duplication event in amphioxus generated SoxB1c and a second gene whose consecutive duplication led to SoxB1a and SoxB1b (Fig.…”

Section: Phylogeny Of Soxb Genesmentioning

confidence: 98%

“…Even among deuterostome lineages, orthologs are not easily identified as independent duplication events most likely occurred in the different lineages [26]. In the sea urchin Strongylocentrotus purpuratus and the urochordate Ciona intestinalis, only a single SoxB1 gene is present.…”

Section: Phylogeny Of Soxb Genesmentioning

confidence: 99%

Having it both ways: Sox protein function between conservation and innovation

Guth

Wegner

2008

Cell. Mol. Life Sci.

153

122

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Transcription factors of the Sox family arose around the advent of multicellularity in animals, arguing that their ability to regulate the expression of extracellular matrix, cell adhesion and signaling molecules may have been instrumental in the generation of metazoans. In particular, during vertebrate evolution, the Sox family experienced a phase of expansion that led to the appearance of groups of highly homologous Sox proteins and the division of existing Sox protein functions among group members. It furthermore allowed Sox transcription factors to acquire numerous novel functions. These past events of subfunctionalization and neofunctionalization can still be recognized today in all groups of the Sox family. They have led to partial functional redundancies, but also to interesting species-specific variations in the developmental roles of Sox proteins as shown here for the SoxB and the SoxE groups.

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“…In amphioxus, functional protein-protein interactions and protein/DNA interactions were also tested for members of the Pax-Six-Eya-Dach (dachsund) network and have been shown to be relatively similar to those described in vertebrates (Kozmik et al, 2007). Moreover, other orthologues of genes expressed in the vertebrate placodes, such as paired-like homeodomain transcription factor (Pitx), sex-determining region Ybox B1c (SoxB1c), Col/Olf-1/EBF (Coe) or brain 3 (Brn3; Pou4f1 -Mouse Genome Informatics), are also expressed in amphioxus epidermal sensory cells (Meulemans and Bronner-Fraser, 2007a). Again, these data suggest that a pre-existing network, which is implicated in sensory epidermal cell formation in the ancestor of chordates, was recruited for placode formation during evolution.…”

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confidence: 97%

Evolutionary crossroads in developmental biology: amphioxus

2011

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SummaryThe phylogenetic position of amphioxus, together with its relatively simple and evolutionarily conserved morphology and genome structure, has led to its use as a model for studies of vertebrate evolution. In particular, the recent development of technical approaches, as well as access to the complete amphioxus genome sequence, has provided the community with tools with which to study the invertebrate-chordate to vertebrate transition. Here, we present this animal model, discussing its life cycle, the model species studied and the experimental techniques that it is amenable to. We also summarize the major findings made using amphioxus that have informed us about the evolution of vertebrate traits.Key words: Cephalochordates, Vertebrate evolution, Branchiostoma, Amphioxus, Lancelet Introduction Amphioxus (also called lancelets or cephalochordates) form one of the three chordate subphyla, along with urochordates (see Glossary, Box 1) and vertebrates (Schubert et al., 2006) (Fig. 1A). They form a small group comprising about 35 species (Poss and Boschung, 1996). The number of genera within the cephalochordate subphylum has long been debated, but recent molecular phylogenetic studies show that cephalochordates are divided into three genera (Kon et al., 2007) (Fig. 1B): Branchiostoma, Epigonichthys and Asymmetron.Described for the first time in 1774 (Pallas, 1774), lancelets were classified as molluscs and were called Limax lanceolatus. Later, in 1834, they were renamed as Branchiostoma lubricus (Costa, 1834) and classified as animals closely related to vertebrates. The first to use the name Amphioxus was William Yarrell, who named them Amphioxus lanceolatus and for the first time described their notochord (see Glossary, Box 1), the defining morphological trait of chordates (Yarrell, 1836). After these initial studies, and until the beginning of the 20th century, amphioxus was considered to be a vertebrate. A consensus was then reached whereby amphioxus were considered to be the closest living relatives of vertebrates, with urochordates representing the most basally divergent chordate lineage. These evolutionary relationships were based on morphological characteristics and on some molecular studies of rRNA genes (Winchell et al., 2002). However, in 2006, based on large molecular data set analyses, it was established that cephalochordates represent the most basally divergent lineage of chordates, being the sister group of urochordates and vertebrates (Bourlat et al., 2006; Delsuc et al., 2006) (Fig. 1A).The adult anatomy of amphioxus is vertebrate-like, but simpler. Amphioxus possess typical chordate characters, such as a dorsal hollow neural tube and notochord, a ventral gut and a perforated pharynx with gill slits, segmented axial muscles and gonads, a postanal tail, a pronephric kidney, and homologues of the thyroid gland and adenohypophysis (the endostyle and pre-oral pit, respectively) ( Fig. 2A). However, they lack typical vertebrate-specific structures, such as paired sensory organs (image-forming eye...

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The Amphioxus SoxB Family: Implications for the Evolution of Vertebrate Placodes

Cited by 67 publications

References 66 publications

Formation of Nervous Systems and Neural Stem Cells in Ascidians

Formation of Nervous Systems and Neural Stem Cells in Ascidians

Having it both ways: Sox protein function between conservation and innovation

Evolutionary crossroads in developmental biology: amphioxus

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