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Biology

Swarthmore College

Biology Faculty Works

Chordate evolution

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Establishment Of Lateral Organ Asymmetries In The Invertebrate Chordate, Ciona Intestinalis, Karl Palmquist , '17, Bradley Justin Davidson , '91 Dec 2017

Establishment Of Lateral Organ Asymmetries In The Invertebrate Chordate, Ciona Intestinalis, Karl Palmquist , '17, Bradley Justin Davidson , '91

Biology Faculty Works

Background: The evolutionary emergence and diversification of the chordates appear to involve dramatic changes in organ morphogenesis along the left/right axis. However, the ancestral chordate mechanism for establishing lateral asymmetry remains ambiguous. Additionally, links between the initial establishment of lateral asymmetry and subsequent asymmetries in organ morphogenesis are poorly characterized. Results: To explore asymmetric organ morphogenesis during chordate evolution, we have begun to characterize left/right patterning of the heart and endodermal organs in an invertebrate chordate, Ciona intestinalis. Here, we show that Ciona has a laterally asymmetric, right-sided heart. Our data indicate that cardiac lateral asymmetry requires H+/K+ ion flux, …


Fibronectin Contributes To Notochord Intercalation In The Invertebrate Chordate, Ciona Intestinalis, F. Segade, C. Cota, A. Famiglietti, A. Cha, Bradley Justin Davidson , '91 Jan 2016

Fibronectin Contributes To Notochord Intercalation In The Invertebrate Chordate, Ciona Intestinalis, F. Segade, C. Cota, A. Famiglietti, A. Cha, Bradley Justin Davidson , '91

Biology Faculty Works

Background: Genomic analysis has upended chordate phylogeny, placing the tunicates as the sister group to the vertebrates. This taxonomic rearrangement raises questions about the emergence of a tunicate/vertebrate ancestor. Results: Characterization of developmental genes uniquely shared by tunicates and vertebrates is one promising approach for deciphering developmental shifts underlying acquisition of novel, ancestral traits. The matrix glycoprotein Fibronectin (FN) has long been considered a vertebrate-specific gene, playing a major instructive role in vertebrate embryonic development. However, the recent computational prediction of an orthologous “vertebrate-like” Fn gene in the genome of a tunicate, Ciona savignyi, challenges this viewpoint suggesting that Fn …