developmental basis of evolutionneural crest groups • cephalic, leave before neural folds close...
TRANSCRIPT
![Page 1: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/1.jpg)
Developmental Basis of Evolution
![Page 2: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/2.jpg)
Evolution• Building blocks present early
• -genes gave rise to position and axes
• HOX (A-P), SOG/Chordin (DV), Distalless (P-D), PAX (eye)- insect/chordate
• Urbilateria- cartoon on following slides
• evolution by tinkering rather than developing new genes-
• most established before Cambrian explosion when 37 phyla were evident
• modularity- building blocks available
![Page 3: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/3.jpg)
Major events in evolution-mitochondria/chloroplasts (O2)-meiosis-multicellularity, embryos-axes
![Page 4: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/4.jpg)
Modules
• Genes–Change in reading frame–Change in upstream region
• Inductive interactions–Paracrines and receptors–Juxtacrines
• Tissues–Specified, determined, stem cells–Migration
![Page 5: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/5.jpg)
Gene Families
• Gene duplication followed by change of function
• Change in pattern of expression• Change in role of transcription factors
• Globin, Hox genes
![Page 6: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/6.jpg)
![Page 7: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/7.jpg)
Heterotopy- Change in location
![Page 8: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/8.jpg)
Mammal
![Page 9: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/9.jpg)
Hox genes
• Proximal-distal pattern set by hox A
• Anterior-posterior pattern set by hox D
• Examples of mutations -synpolydactyly – -hoxD13 mutated
![Page 10: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/10.jpg)
Early Vertebrate Evolution
• Dorsal nerve cord/notochord• Myomeres-locomotion• Filter feeders to carnivores
–Cephalization- brain and sensory structures–Jaws–Skull
• Limbs- tetrapods
![Page 11: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/11.jpg)
Vertebrate origins
• Basics in Amphioxus–simple brain with
retina, notochord
–neural crest equivalent
• change from filter feeding to raptorial
• mouth bones, teeth
• head development strongest
Heterochrony- urochordata metamorphosis -tunicates -larvaceansTail remains in adult(handout)
![Page 12: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/12.jpg)
Neural Crest Groups
• Cephalic, leave before neural folds close– form pharyngeal pouches, craniofacial, cranial nerves
• Trunk, – dorsal path- melanocytes
– ventral path (through ant sclerotome)- dorsal root ganglion, sympathetic ganglion, adrenal medulla
• Vagal (somites 1-7)
• Cardiac (myel, somites 1-3)– travel via blood vessels, form septa between aorta and
pulmonary artery
• Cervical (somite 28)
![Page 13: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/13.jpg)
![Page 14: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/14.jpg)
![Page 15: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/15.jpg)
New cell types (ectomes) arise in vertebrates
• Origin of neural crest cells at boundary of epidermis and neural plate
• Cell types present in neochordates but they do not migrate
• Transcription factors AP2 and distalless present in cephalochordates in non-neural ectoderm
• These genes are transcribed in vertebrates and leads to migration of neural crest cells
• Pleuripotent-specified-determined-differentiated
![Page 16: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/16.jpg)
Limb Formation• Limb field established
through HoxC-6 gene near first thoracic vertebra, near pronephros
• -may be initiated by RA from Hensen’s node which would activate Hox genes
• Axes established early:
• A-P (shh)- by neurula• D-V (wnt-7)
• P-D (Hox, FGF, distalless)
Limb field
Humerus rad/ulna carpals/phalanges
femur tibia/fibula tarsals/phalanges
![Page 17: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/17.jpg)
Limb Bud
• Hox 4,5 (forelimb)
• Hox 9-11 (hindlimb)
• Tbx (transcription factor)
• FGF
• distalless establishes evaginations
• Apical Epidermal Ridge stimulated by mesoderm (and vice versa)
• -cells enlarge and secrete FGF8,4
FGF
shh
Progress zone-controlled by FGF
![Page 18: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/18.jpg)
Heterometry-change in amount-allometry
![Page 19: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/19.jpg)
Pharyngula- most vulnerable stage-great deal of regulation before this stage-many inductive events but they are modular
![Page 20: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/20.jpg)
Formation of the jaw
![Page 21: Developmental Basis of EvolutionNeural Crest Groups • Cephalic, leave before neural folds close –form pharyngeal pouches, craniofacial, cranial nerves • Trunk, –dorsal path-](https://reader033.vdocuments.us/reader033/viewer/2022052803/5f2bc3c92c031e356a06ce33/html5/thumbnails/21.jpg)
Neural crest cells as modules