A median fin derived from the lateral plate mesoderm and the origin of paired fins

The development of paired appendages was a key innovation during evolution and facilitated the aquatic to terrestrial transition of vertebrates. Largely derived from the lateral plate mesoderm (LPM), one hypothesis for the evolution of paired fins invokes derivation from unpaired median fins via a pair of lateral fin folds located between pectoral and pelvic fin territories1. Whilst unpaired and paired fins exhibit similar structural and molecular characteristics, no definitive evidence exists for paired lateral fin folds in larvae or adults of any extant or extinct species. As unpaired fin core components are regarded as exclusively derived from paraxial mesoderm, any transition presumes both co-option of a fin developmental programme to the LPM and bilateral duplication2. Here, we identify that the larval zebrafish unpaired pre-anal fin fold (PAFF) is derived from the LPM and thus may represent a developmental intermediate between median and paired fins. We trace the contribution of LPM to the PAFF in both cyclostomes and gnathostomes, supporting the notion that this is an ancient trait of vertebrates. Finally, we observe that the PAFF can be bifurcated by increasing bone morphogenetic protein signalling, generating LPM-derived paired fin folds. Our work provides evidence that lateral fin folds may have existed as embryonic anlage for elaboration to paired fins

A median fin derived from the lateral plate mesoderm and the origin of paired fins

The development of paired appendages was a key innovation during evolution and facilitated the aquatic to terrestrial transition of vertebrates. Largely derived from the lateral plate mesoderm (LPM), one hypothesis for the evolution of paired fins invokes derivation from unpaired median fins via a pair of lateral fin folds located between pectoral and pelvic fin territories1. Whilst unpaired and paired fins exhibit similar structural and molecular characteristics, no definitive evidence exists for paired lateral fin folds in larvae or adults of any extant or extinct species. As unpaired fin core components are regarded as exclusively derived from paraxial mesoderm, any transition presumes both co-option of a fin developmental programme to the LPM and bilateral duplication2. Here, we identify that the larval zebrafish unpaired pre-anal fin fold (PAFF) is derived from the LPM and thus may represent a developmental intermediate between median and paired fins. We trace the contribution of LPM to the PAFF in both cyclostomes and gnathostomes, supporting the notion that this is an ancient trait of vertebrates. Finally, we observe that the PAFF can be bifurcated by increasing bone morphogenetic protein signalling, generating LPM-derived paired fin folds. Our work provides evidence that lateral fin folds may have existed as embryonic anlage for elaboration to paired fins.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)Published versionThis work was funded by the Industry Aligned Fund (IAF) Agency for Science, Technology and Research (grant to T.J.C. and K.-W.T.); Ministry of Education (MoE) Tier 3 (grant 2016-T3-1-005 to T.J.C., C.W. and H.M.); Ministry of Education (MoE) Tier 1 (grant 2016-T1-001-055 to T.J.C. and C.Z.); Ministry of Education (MoE) Tier 2 (grant MOE-T2EP30221-0008 to C.W.); the Company of Biologists (travelling fellowship to M.J.T.); the National Science Foundation (grants IOS-1853949 to M.C.D. and 2203311 to C.M.); the Swiss National Science Foundation Sinergia (grant CRSII5_180345 to C.M.); the Swiss Bridge Foundation (C.M.); Additional Ventures Single Ventricle Research Fund (SVRF) (grant 1048003 to C.M.); the University of Colorado School of Medicine Anschutz Medical Campus and the Children’s Hospital Colorado Foundation (C.M.); the National Institutes of Health (NIH), National Institute of General Medical Sciences (grants 1T32GM141742-01 to H.R.M. and 3T32GM121742-02S1 to H.R.M.); Australian Research Council (discovery grant DP200103219 to F.J.T. and P.D.C); National Health and Medical Research Council (senior principal research fellow APP1136567 to P.D.C.); and the NIH (grant R35NS111564 to J.S. and M.E.B.)

Elucidation of the genetic causes of bicuspid aortic valve disease.

AIMS The present study aims to characterize the genetic risk architecture of bicuspid aortic valve (BAV) disease, the most common congenital heart defect. METHODS AND RESULTS We carried out a genome-wide association study (GWAS) including 2236 BAV patients and 11 604 controls. This led to the identification of a new risk locus for BAV on chromosome 3q29. The single nucleotide polymorphism rs2550262 was genome-wide significant BAV associated (P = 3.49 × 10-08) and was replicated in an independent case-control sample. The risk locus encodes a deleterious missense variant in MUC4 (p.Ala4821Ser), a gene that is involved in epithelial-to-mesenchymal transformation. Mechanistical studies in zebrafish revealed that loss of Muc4 led to a delay in cardiac valvular development suggesting that loss of MUC4 may also play a role in aortic valve malformation. The GWAS also confirmed previously reported BAV risk loci at PALMD (P = 3.97 × 10-16), GATA4 (P = 1.61 × 10-09), and TEX41 (P = 7.68 × 10-04). In addition, the genetic BAV architecture was examined beyond the single-marker level revealing that a substantial fraction of BAV heritability is polygenic and ∼20% of the observed heritability can be explained by our GWAS data. Furthermore, we used the largest human single-cell atlas for foetal gene expression and show that the transcriptome profile in endothelial cells is a major source contributing to BAV pathology. CONCLUSION Our study provides a deeper understanding of the genetic risk architecture of BAV formation on the single marker and polygenic level

The effect of transcatheter aortic valve implantation approaches on mortality

Objectives We aimed to evaluate the effect of transcatheter aortic valve implantation (TAVI) approaches on mortality and identify effect modifiers and predictors for mortality.Background Alternative access routes to transfemoral (TF) TAVI include the surgical intra-thoracic direct-aortic (DA) and transapical (TA) approach. TA TAVI has been associated with a higher mortality rate. We hypothesized that this is related to effect modifiers, in particular the left ventricular ejection fraction (LVEF).Methods This multicentre study derived its data from prospective registries. To adjust for confounders, we used propensity-score based, stabilized inverse probability weighted Cox regression models.Results In total, 5,910 patients underwent TAVI via TF (N = 4,072), DA (N = 524), and TA (N = 1,314) access. Compared to TF, 30-day mortality was increased among DA (HR 1.87, 95%CI 1.26-2.78, p = .002) and TA (HR 3.34, 95%CI 2.28-4.89, p < .001) cases. Compared to TF, 5-year mortality was increased among TA cases (HR 1.50, 95%CI 1.24-1.83, p < .001). None of the variables showed a significant interaction between the approaches and mortality. An impaired LVEF (<= 35%) increased mortality in all approaches.Conclusions The surgical intra-thoracic TA and DA TAVI are both associated with a higher 30-day mortality than TF TAVI. TA TAVI is associated with a higher 5-year mortality than TF TAVI. The DA approach may therefore have some advantages over the TA approach when TF access is not feasible

The effect of transcatheter aortic valve implantation approaches on mortality

Objectives We aimed to evaluate the effect of transcatheter aortic valve implantation (TAVI) approaches on mortality and identify effect modifiers and predictors for mortality.Background Alternative access routes to transfemoral (TF) TAVI include the surgical intra-thoracic direct-aortic (DA) and transapical (TA) approach. TA TAVI has been associated with a higher mortality rate. We hypothesized that this is related to effect modifiers, in particular the left ventricular ejection fraction (LVEF).Methods This multicentre study derived its data from prospective registries. To adjust for confounders, we used propensity-score based, stabilized inverse probability weighted Cox regression models.Results In total, 5,910 patients underwent TAVI via TF (N = 4,072), DA (N = 524), and TA (N = 1,314) access. Compared to TF, 30-day mortality was increased among DA (HR 1.87, 95%CI 1.26-2.78, p = .002) and TA (HR 3.34, 95%CI 2.28-4.89, p < .001) cases. Compared to TF, 5-year mortality was increased among TA cases (HR 1.50, 95%CI 1.24-1.83, p < .001). None of the variables showed a significant interaction between the approaches and mortality. An impaired LVEF (<= 35%) increased mortality in all approaches.Conclusions The surgical intra-thoracic TA and DA TAVI are both associated with a higher 30-day mortality than TF TAVI. TA TAVI is associated with a higher 5-year mortality than TF TAVI. The DA approach may therefore have some advantages over the TA approach when TF access is not feasible