The evolutionary origin of bilaterian smooth and striated myocytes
- European Molecular Biology Laboratory, Germany
Figures
Figure 1
Ultrastructure and core regulatory complexes of myocyte types.
(A) Schematic smooth and striated ultrastructures. Electron-dense granules called ‘dense bodies’ separate adjacent myofibrils. Dense bodies are scattered in smooth muscles, but aligned in striated …
Figure 2 with 2 supplements
Development and ultrastructure of visceral and somatic musculature in Platynereis larvae and juveniles.
(A) Development of visceral musculature. All panels are 3D renderings of rhodamine-phalloidin staining imaged by confocal microscopy. Visceral muscles have been manually colored green and somatic …
Figure 2—figure supplement 1
Gut patterning in Platynereis six dpf larvae.
(A) six dpf Platynereis larva stained with phalloidin and DAPI to show tripartite gut organization. Maximal Z-projection of a confocal stack, ventral view, anterior side up. The plane of the …
Figure 2—figure supplement 2
Formation of the visceral musculature observed in cross-section.
(A–C) Virtual cross-sections of confocal Z-stacks of Platynereis larvae stained with DAPI and phalloidin. Dorsal side up. (A’–C’) Schematic drawings of the same individuals. Note the progressive …
Figure 3 with 5 supplements
Expression of smooth and striated muscle markers in Platynereis larvae.
Animals have been stained by WMISH and observed in bright-field Nomarski microscopy. Ventral views, anterior side up. Scale bar: 25 μm. (A–D) Expression patterns of the striated marker ST-MHC and …
Figure 3—figure supplement 1
Expression of striated muscle markers in Platynereis larvae.
(A–O) Larvae stained by WMISH and observed in bright-field Nomarski microscopy. Ventral views, anterior side up. Scale bar is 20 μm for 48 hpf and 25 μm for the two other stages. (P) Foregut …
Figure 3—figure supplement 2
Expression of striated muscle markers in the six dpf Platynereis larva.
Animals have been stained by WMISH and observed by confocal microscopy (DAPI fluorescence and NBT/BCIP 633 nm reflection). All striated effector genes are expressed in all somatic muscles examined. …
Figure 3—figure supplement 3
Expression of smooth muscle markers in Platynereis larvae.
(A–F) Animals are stained by WMISH and observed by Nomarski bright-field microscopy. Ventral views, anterior side up. Yellow arrows: expression in the foregut mesoderm. White dashed lines: outline …
Figure 3—figure supplement 4
Molecular profile of midgut muscles in the six dpf larva.
All panels are Z-projections of confocal planes, ventral views, anterior side up. Blue: DAPI, red: NBT/BCIP precipitate. White dashed line: midgut/hindgut, yellow dashed ellipse: stomodeum. (A–E) …
Figure 3—figure supplement 5
General muscle markers are expressed in both smooth and striated muscles.
All panels show gene expression visualized by WMISH. (A–F) actin expression. (A–B) bright-field micrographs in Nomarski optics. (A) is an apical view, (B) is a ventral view. Abbreviations: dlm, …
Figure 4
Contraction speed quantifications of smooth and striated muscles.
(A–B) Snapshots of a time lapse live confocal imaging of a late nectochaete larva expressing fluorescent markers. Ventral view of the two posterior-most segments, anterior is up. (C) Snapshots of a …
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Figure 4—source data 1
Contraction speed values measured for somatic and visceral muscles.
- https://doi.org/10.7554/eLife.19607.013
Figure 5
Platynereis gut peristalsis is independent of nervous inputs and dependent on gap junctions.
(A) Two-month-old juvenile mounted in 3% low-melting point (LMP) agarose for live imaging. (B) Snapshots of a confocal live time-lapse imaging of the animal shown in A. Gut is observed by detecting …
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Figure 5—source data 1
Peristalsis waves quantifications in control and Brefeldin A-treated worms.
Control and treated animals are respectively numbered Ctrl1, Ctrl2, … etc. and BfdA1, BfdA2, … etc. Contraction events are named e1, e2, … etc. Numbers in columns B and E are the speed of individual contraction waves as defined in Figure 5C. Contraction events and the recurrence of contraction events are defined in the legend of Figure 5.
- https://doi.org/10.7554/eLife.19607.017
Figure 6
The enteric nerve net of Platynereis.
(A) Immunostaining for acetylated tubulin, visualizing neurites of the enteric nerve plexus. Z-projection of a confocal stack at the level of the midgut. Anterior side up. (B) Same individual as in …
Figure 7 with 3 supplements
The evolutionary tree of animal contractile cell types.
Bilaterian smooth and striated muscles split before the last common protostome/deuterostome ancestor. Bilaterian myocytes are split into two monophyletic cell type clades: an ancestrally SM-MHC+ …
Figure 7—figure supplement 1
Evolution of myogenic Core Regulatory Complexes (CoRCs) in Bilateria.
Transcription factor families are depicted as in Figure 1. Direct contact indicates proven binding. Co-option of the fast/striated module happened on three occasions: in Drosophila gut myocytes, and …
Figure 7—figure supplement 2
Ancestral state reconstructions of the ultrastructure of midgut/hindgut and heart myocytes.
(A) Distribution, and ancestral state reconstruction, of midgut smooth muscles in Bilateria. Ancestral states were inferred using Parsimony and Maximum Likelihood (ML) (posterior probabilities …
Figure 7—figure supplement 3
Domain structure, phylogeny and expression patterns of members of the calponin gene family.
(A) Domain structure of calponin-related proteins in bilaterians. Calponin is characterized by a Calponin Homology (CH) domain with several calponin repeats, while Transgelin is characterized by a …
Videos
Video 1
Live imaging of somatic muscle contraction visualized by GCaMP6s.
Dorsal view of a three dpf Platynereis larva injected (at the zygote stage) with a mRNA encoding GCaMP6s and mounted in 3% LMP agar between a slide and a cover slip. Anterior side is up. Left side …
Video 2
Live imaging of visceral muscle contraction visualized by FM-464FX.
Ventral view of a six dpf Platynereis larva stained with the vital dye FM-464FX and mounted in 3% LMP agar between a slide and a cover slip. Red fluorescence signal is shown. Anterior side is up. …
Video 3
Live imaging of gut peristalsis in a control 2-month-old juvenile worm.
Lateral view of an individual stained with FM-464FX and mounted in 3% LMP agar between a slide and a cover slip. Left side is the transmitted light signal and right side is the red fluorescence …
Video 4
Live imaging of gut peristalsis in a Brefeldin-A-treated 2-month-old juvenile worm.
Ventral view of an individual treated with 180 μM Brefeldin-A, stained with FM-464FX (not shown) and mounted in 3% LMP agar between a slide and a cover slip. Transmitted light signal is shown. Note …
Additional files
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Supplementary file 1
Phylogenetic trees of the markers investigated.
(A) Simplified Maximum Likelihood (ML) tree for Myosin Regulatory Light Chain (full tree in panel M), rooted with Calmodulin, which shares an EF-hand calcium-binding domain with MRLC. (B) ML tree for FoxF, rooted with FoxQ1, the probable closest relative of the FoxF family (Shimeld et al., 2010). (C) MrBayes tree for bilaterian ZASP/LBD3, rooted with the cnidarian ortholog (Steinmetz et al., 2012). (D) ML tree for bilaterian Myosin Heavy Chain, rooted at the (pre-bilaterian) duplication between smooth and striated MHC (Steinmetz et al., 2012). (E) MrBayes tree for Mef2, rooted by the first splice isoform of the cnidarian ortholog (Genikhovich and Technau, 2011). (F) MrBayes tree for Titin, rooted at the protostome/deuterostome bifurcation (Titin is a bilaterian novelty). (G) MrBayes tree for Troponin T, rooted at the protostome/deuterostome bifurcation (Troponin T is a bilaterian novelty). (H) MrBayes tree for Troponin I, rooted by the Calponin/Transgelin family, which shares an EF-hand calcium-binding domain with Troponin I. (I) MrBayes tree for MyoD, rooted at the protostome/deuterostome bifurcation (MyoD is a bilaterian novelty). (J) MrBayes tree for Myocardin, rooted at the protostome/deuterostome bifurcation (the Drosophila myocardin ortholog is established [Han et al., 2004]). (K) Complete MRLC tree. Species names abbreviations: Pdu: Platynereis dumerilii; Xenla: Xenopus laevis; Mus: Mus musculus; Hsa: Homo sapiens; Dre: Danio rerio; Gga: Gallus gallus; Dme: Drosophila melanogaster; Cte: Capitella teleta; Patvu: Patella vulgata; Brafl: Branchiostoma floridae; Nve or Nemv: Nematostella vectensis; Acdi: Acropora digitifera; Expal: Exaiptasia pallida; Rat: Rattus norvegicus; Sko: Saccoglossus kowalevskii; Limu or Lpo: Limulus polyphemus; Trib or Trca: Tribolium castaneum; Daph: Daphnia pulex; Prcau: Priapulus caudatus; Cgi or Cgig: Crassostrea gigas; Ling or Linan: Lingula anatina; Hdiv: Haliotis diversicolor; Apcal or Aca: Aplysia californica; Spu: Strongylocentrotus purpuratus; Poli or Polis: Polistes dominula; Cin or Cint: Ciona intestinalis; Hro: Helobdella robusta; Bos: Bos taurus; Capsa: Capsaspora owczarzaki; Thtr: Thecamonas trahens; Lpo:; Bga: Biomphalaria glabrata; Cel: Caenorhabditis elegans; Tt: Terebratalia transversa; Octo: Octopus vulgaris; Sma: Schmidtea mediterranea; Bbe: Branchiostoma belcheri, Batden: Batrachochytrium dendrobaditis; Monve: Mortierella verticillata; Alloma: Allomyces macrogynus; Salpun: Spizellomyces punctatus; Mucor: Mucor racemosus; Lichco: Lichtheimia corymbifera; Ephmu: Ephydatia muelleri; Sycon: Sycon ciliatum; Amqu: Amphimedon queenslandica; Osc: Oscarella lobularis; Metse: Metridium senile; Pfu: Pinctada fucata; Rypa: Riftia pachyptila; Plma: Placopecten magellanicus; Air: Argopecten irradians; Scolop: Scolopendra gigantea; Artfra: Artemia franciscana; Bmor: Bombyx mori; Loa: Loa loa; Necator-am: Necator americanus; Trichi: Trichinella spiralis; Asc: Ascaris lumbricoides; Wuch: Wucheria bancrofti; Ancy: Ancylostoma duodenale; Callorinc: Callorhinchus milii; Dana: Danaus plexippus; Anop: Anopheles gambiae; Asty: Astyanax mexicanus; Oreo: Oreochromis niloticus; Icta: Ictalurus punctatus.
- https://doi.org/10.7554/eLife.19607.025
