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Early Cranial Patterning In The Direct-Developing Frog Eleutherodactylus Coqui Revealed Through Gene Expression, Ryan Kerney, Joshua Gross, James Hanken
Early Cranial Patterning In The Direct-Developing Frog Eleutherodactylus Coqui Revealed Through Gene Expression, Ryan Kerney, Joshua Gross, James Hanken
Ryan Kerney
Genetic and developmental alterations associated with the evolution of amphibian direct development remain largely unexplored. Specifically, little is known of the underlying expression of skeletal regulatory genes, which may reveal early modifications to cranial ontogeny in direct-developing species. We describe expression patterns of three key skeletal regulators (runx2, sox9, and bmp4) along with the cartilage-dominant collagen 2a1 gene (col2a1) during cranial development in the direct- developing anuran, Eleutherodactylus coqui. Expression patterns of these regulators reveal transient skeletogenic anlagen that correspond to larval cartilages, but which never fully form in E. coqui. Suprarostral anlagen in the frontonasal processes are detected through …
Skeletal Advance And Arrest In Giant Non-Metamorphosing African Clawed Frog Tadpoles (Xenopus Laevis: Daudin), Ryan Kerney, Richard Wassersug, Brian Hall
Skeletal Advance And Arrest In Giant Non-Metamorphosing African Clawed Frog Tadpoles (Xenopus Laevis: Daudin), Ryan Kerney, Richard Wassersug, Brian Hall
Ryan Kerney
This study examines the skeletons of giant non-metamorphosing (GNM) Xenopus laevis tadpoles, which arrest their development indefinitely before metamorphosis, and grow to excessively large sizes in the absence of detectable thyroid glands. Cartilage growth is isometric; however, chondrocyte size is smaller in GNM tadpoles than in controls. Most cartilages stain weakly with alcian blue, and several cartilages are calcified (unlike con- trols). However, cartilages subjacent to periosteum-derived bone retain strong affinities for alcian blue, indicat- ing a role for periosteum-derived bone in the retention of glycosaminoglycans during protracted larval growth. Bone formation in the head, limb, and axial skeletons is …
Cranial Ontogeny In Philautus Silus (Anura: Ranidae: Rhacophorinae) Reveals Few Similarities With Other Direct-Developing Anurans, Ryan Kerney, Madhava Meegaskumbura, Kelum Manamendra-Arachchi, James Hanken
Cranial Ontogeny In Philautus Silus (Anura: Ranidae: Rhacophorinae) Reveals Few Similarities With Other Direct-Developing Anurans, Ryan Kerney, Madhava Meegaskumbura, Kelum Manamendra-Arachchi, James Hanken
Ryan Kerney
Direct development has evolved in rhaco- phorine frogs independently from other anuran lineages, thereby offering an opportunity to assess features associ- ated with this derived life history. Using a developmen- tal series of the direct-developing Philautus silus (Ranidae: Rhacophorinae) from Sri Lanka, we examine features of cranial morphology that are part of a suite of adaptations that facilitate feeding in free-living tadpoles, but have been changed or lost in other direct-developing lineages. Larval-specific upper jaw cartilages, which are absent from many non-rhacophorine direct-developing species (such as Eleutherodactylus coqui), develop in embryos of P. silus. Similarly, lower jaw cartilages ini- tially …