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Fig. 1
Zebrafish vegfc mutants lack lymphatic vessels, but appear otherwise normal. (A-D) Confocal projections of Tg(fli1a:EGFP) show unaltered overall morphology and blood vasculature in vegfchu5055 mutants (B) compared with wild type (A). The TD (C, arrows) is absent in vegfchu5055 (D, asterisks). (E) Positional cloning linked alleles hu6124 and hu5055 to large regions of chromosome 1, containing the vegfc gene. For hu6124, 13 recombinant embryos identified at z9394 were reduced to four recombinant embryos common with z5508, identifying linkage in a large region containing vegfc. For hu5055, eight recombinant embryos at z2691 and 33 different recombinant embryos at z4694 flanked a large region of chromosome 1, also containing vegfc. (F) Sequencing of vegfc alleles. hu6410 encodes an early stop allele leading to a predicted truncated protein lacking the core (VHD) region. hu5142, hu6124 and hu5055 encode missense mutations, all in highly conserved regions of the protein (G) and predicted to be damaging by PolyPhen-2 (Adzhubei et al., 2010) with scores of 1 out of 1. (G) Alleles hu5055, hu6410, hu6124 and hu5142 all encode mutations in regions that are conserved across multiple species. (H) Alleles hu5055 and hu6410 fail to complement, with trans-heterozygote embryos displaying a lack of lymphatic structures; phenotype scored as percentage extent of thoracic duct over ten somites (total number of embryos scored n=212). (I,J) The penetrance of vegfc mutant phenotypes varies, as shown by the variable number of PLs (I) or TD extent (J). The hu6410 allele (L107X) shows the most severe defects in heterozygous and homozygous mutants, whereas hu5055 does not show haplo-insufficiency phenotypes. (K) vegfchu5055 genetically interacts with vegfr3hu4602 in trans-heterozygous embryos. Confocal projections of Tg(fli1a:EGFP; kdr-l:mCherry) showing examples of the heterogeneity observed during TD development at 5 dpf in vegfc+/-; vegfr3+/- embryos. Arrows indicate the thoracic duct, asterisks indicate absence of thoracic duct.