scholarly journals Decision letter: Embryonic origin and serial homology of gill arches and paired fins in the skate, Leucoraja erinacea

2020 ◽  
Author(s):  
Elizabeth M Sefton ◽  
Robert Cerny
2020 ◽  
Author(s):  
Victoria A. Sleight ◽  
J. Andrew Gillis

AbstractPaired fins are a defining feature of the jawed vertebrate body plan, but their evolutionary origin remains unresolved. Gegenbaur proposed that paired fins evolved as gill arch serial homologues, but this hypothesis is now widely discounted, owing largely to the presumed distinct embryonic origins of these structures from mesoderm and neural crest, respectively. Here, we use cell lineage tracing to test the embryonic origin of the pharyngeal and paired fin skeleton in the skate (Leucoraja erinacea). We find that while the jaw and hyoid arch skeleton derive from neural crest, and the pectoral fin skeleton from mesoderm, the gill arches are of dual origin, receiving contributions from both germ layers. We propose that gill arches and paired fins are serially homologous as derivatives of a continuous, dual-origin mesenchyme with common skeletogenic competence, and that this serial homology accounts for their parallel anatomical organization and shared responses to axial patterning signals.


eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Victoria A Sleight ◽  
J Andrew Gillis

Paired fins are a defining feature of the jawed vertebrate body plan, but their evolutionary origin remains unresolved. Gegenbaur proposed that paired fins evolved as gill arch serial homologues, but this hypothesis is now widely discounted, owing largely to the presumed distinct embryonic origins of these structures from mesoderm and neural crest, respectively. Here, we use cell lineage tracing to test the embryonic origin of the pharyngeal and paired fin skeleton in the skate (Leucoraja erinacea). We find that while the jaw and hyoid arch skeleton derive from neural crest, and the pectoral fin skeleton from mesoderm, the gill arches are of dual origin, receiving contributions from both germ layers. We propose that gill arches and paired fins are serially homologous as derivatives of a continuous, dual-origin mesenchyme with common skeletogenic competence, and that this serial homology accounts for their parallel anatomical organization and shared responses to axial patterning signals.


Author(s):  
Stéphane Schmitt

The problem of the repeated parts of organisms was at the center of the biological sciences as early as the first decades of the 19th century. Some concepts and theories (e.g., serial homology, unity of plan, or colonial theory) introduced in order to explain the similarity as well as the differences between the repeated structures of an organism were reused throughout the 19th and the 20th century, in spite of the fundamental changes during this long period that saw the diffusion of the evolutionary theory, the rise of experimental approaches, and the emergence of new fields and disciplines. Interestingly, this conceptual heritage was at the core of any attempt to unify the problems of inheritance, development, and evolution, in particular in the last decades, with the rise of “evo-devo.” This chapter examines the conditions of this theoretical continuity and the challenges it brings out for the current evolutionary sciences.


1988 ◽  
Vol 263 (26) ◽  
pp. 12801-12804 ◽  
Author(s):  
T R Hansen ◽  
K Imakawa ◽  
H G Polites ◽  
K R Marotti ◽  
R V Anthony ◽  
...  

Author(s):  
Marketa Kaucka ◽  
Bara Szarowska ◽  
Michaela Kavkova ◽  
Maria Eleni Kastriti ◽  
Polina Kameneva ◽  
...  

AbstractMelanocytes are pigmented cells residing mostly in the skin and hair follicles of vertebrates, where they contribute to colouration and protection against UV-B radiation. However, the spectrum of their functions reaches far beyond that. For instance, these pigment-producing cells are found inside the inner ear, where they contribute to the hearing function, and in the heart, where they are involved in the electrical conductivity and support the stiffness of cardiac valves. The embryonic origin of such extracutaneous melanocytes is not clear. We took advantage of lineage-tracing experiments combined with 3D visualizations and gene knockout strategies to address this long-standing question. We revealed that Schwann cell precursors are recruited from the local innervation during embryonic development and give rise to extracutaneous melanocytes in the heart, brain meninges, inner ear, and other locations. In embryos with a knockout of the EdnrB receptor, a condition imitating Waardenburg syndrome, we observed only nerve-associated melanoblasts, which failed to detach from the nerves and to enter the inner ear. Finally, we looked into the evolutionary aspects of extracutaneous melanocytes and found that pigment cells are associated mainly with nerves and blood vessels in amphibians and fish. This new knowledge of the nerve-dependent origin of extracutaneous pigment cells might be directly relevant to the formation of extracutaneous melanoma in humans.


2008 ◽  
Vol 295 (5) ◽  
pp. L858-L865 ◽  
Author(s):  
Kevin Kwong ◽  
Marian Kollarik ◽  
Christina Nassenstein ◽  
Fei Ru ◽  
Bradley J. Undem

The lungs and esophagus are innervated by sensory neurons with somata in the nodose, jugular, and dorsal root ganglion. These sensory ganglia are derived from embryonic placode (nodose) and neural crest tissues (jugular and dorsal root ganglia; DRG). We addressed the hypothesis that the neuron's embryonic origin (e.g., placode vs. neural crest) plays a greater role in determining particular aspects of its phenotype than the environment in which it innervates (e.g., lungs vs. esophagus). This hypothesis was tested using a combination of extracellular and patch-clamp electrophysiology and single-cell RT-PCR from guinea pig neurons. Nodose, but not jugular C-fibers innervating the lungs and esophagus, responded to α,β-methylene ATP with action potential discharge that was sensitive to the P2X3 (P2X2/3) selective receptor antagonist A-317491. The somata of lung- and esophagus-specific sensory fibers were identified using retrograde tracing with a fluorescent dye. Esophageal- and lung-traced neurons from placodal tissue (nodose neurons) responded similarly to α,β-methylene ATP (30 μM) with a large sustained inward current, whereas in neurons derived from neural crest tissue (jugular and DRG neurons), the same dose of α,β-methylene ATP resulted in only a transient rapidly inactivating current or no detectable current. It has been shown previously that only activation of P2X2/3 heteromeric receptors produce sustained currents, whereas homomeric P2X3 receptor activation produces a rapidly inactivating current. Consistent with this, single-cell RT-PCR analysis revealed that the nodose ganglion neurons innervating the lungs and esophagus expressed mRNA for P2X2 and P2X3 subunits, whereas the vast majority of jugular and dorsal root ganglia innervating these tissues expressed only P2X3 mRNA with little to no P2X2 mRNA expression. We conclude that the responsiveness of C-fibers innervating the lungs and esophagus to ATP and other purinergic agonists is determined more by their embryonic origin than by the environment of the tissue they ultimately innervate.


1992 ◽  
Vol 78 (2) ◽  
pp. 140-142 ◽  
Author(s):  
Paola Dal Cin ◽  
Philippe Moerman ◽  
Ivo De Wever ◽  
Herman Van Den Berghe

Cytogenetic analysis on a 7-day-old culture of a fibrothecoma showed only numerical chromosome abnormalities: 57, XX, +4, +5, +6, +10, + 12, +12, +14, +17, +18, +19, +20. The finding of an extra copy of chromosome 12 in mesenchymal tumors, mostly benign and originating from the female genital tract, may possibly point towards their common embryonic origin.


2021 ◽  
Vol 226 (2) ◽  
pp. 519-562 ◽  
Author(s):  
Elena Garcia-Calero ◽  
Lara López-González ◽  
Margaret Martínez-de-la-Torre ◽  
Chen-Ming Fan ◽  
Luis Puelles

AbstractWe focus this report on the nucleus of the lateral olfactory tract (NLOT), a superficial amygdalar nucleus receiving olfactory input. Mixed with its Tbr1-expressing layer 2 pyramidal cell population (NLOT2), there are Sim1-expressing cells whose embryonic origin and mode of arrival remain unclear. We examined this population with Sim1-ISH and a Sim1-tauLacZ mouse line. An alar hypothalamic origin is apparent at the paraventricular area, which expresses Sim1 precociously. This progenitor area shows at E10.5 a Sim1-expressing dorsal prolongation that crosses the telencephalic stalk and follows the terminal sulcus, reaching the caudomedial end of the pallial amygdala. We conceive this Sim1-expressing hypothalamo-amygdalar corridor (HyA) as an evaginated part of the hypothalamic paraventricular area, which participates in the production of Sim1-expressing cells. From E13.5 onwards, Sim1-expressing cells migrated via the HyA penetrate the posterior pallial amygdalar radial unit and associate therein to the incipient Tbr1-expressing migration stream which swings medially past the amygdalar anterior basolateral nucleus (E15.5), crosses the pallio-subpallial boundary (E16.5), and forms the NLOT2 within the anterior amygdala by E17.5. We conclude that the Tbr1-expressing NLOT2 cells arise strictly within the posterior pallial amygdalar unit, involving a variety of required gene functions we discuss. Our results are consistent with the experimental data on NLOT2 origin reported by Remedios et al. (Nat Neurosci 10:1141–1150, 2007), but we disagree on their implication in this process of the dorsal pallium, observed to be distant from the amygdala.


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