BackgroundGenomic 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.ResultsCharacterization 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 may have arisen in the shared tunicate/vertebrate ancestor. Here we verify the presence of a tunicate Fn ortholog. Transgenic reporter analysis was used to characterize a Ciona Fn enhancer driving expression in the notochord. Targeted knockdown in the notochord lineage indicates that FN is required for proper convergent extension.ConclusionsThese findings suggest that acquisition of Fn was associated with altered notochord morphogenesis in the vertebrate/tunicate ancestor.Electronic supplementary materialThe online version of this article (doi:10.1186/s13227-016-0056-4) contains supplementary material, which is available to authorized users.
Anastomotic leak is one of the most feared complications of esophagectomy, leading to prolonged hospital stay, increased postoperative mortality, and additional cost both to the patient and the hospital. Historically, anastomotic leaks have been treated with several techniques including conservative measures, percutaneous or operative drainage, primary surgical repair with buttressing, T-tube drainage, or excision of the esophageal replacement conduit with end esophagostomy. With advances in treatment modalities, including endoscopic stenting, clips and suturing, endoluminal vacuum-assisted closure (EVAC), such leaks increasingly are being managed without operative re-intervention and with salvage of the esophageal replacement conduit. For the purposes of this review, we identified studies analyzing the management of postoperative leak after esophagectomy. We then compared the efficacy of the various newer modalities for closure of anastomotic leaks and gastric conduit defects. We found both esophageal stent and EVAC sponges are effective treatments for closure of anastomotic leak. The chosen treatment modality for salvage of the esophageal replacement conduit is entirely dependent on the patient's clinical status and the surgeon's preference and experience. Emerging endoscopic and endoluminal therapies have increased the armamentarium of tools the esophageal surgeon has to facilitate successful resolution of anastomotic leaks following esophagectomy with reconstruction. While some literature suggests that EVACs have a slightly superior result in conduit success, we question this endorsement as EVACs mostly are utilized for contained leaks, many of which may have healed with conservative measures. This poses a challenge as there is clearly a bias given patient selection.
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