SNAPSHOT SUMMARY: Early Development of Amphibians and Fish pathway (Nodal, Vg1)
ID: 204675 • Letter: S
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SNAPSHOT SUMMARY: Early Development of Amphibians and Fish pathway (Nodal, Vg1) to activate genes nhibitors. These inhibitors include the Noggn, Chorin, and Folstatin, as well as the tr factor Goosecoid encoding B 1. Amphibian cleavage is holoblastic, but it is unequal because of the presence of yolk in the vegetal hemisphere. 2. Amphibian gastrulation begins with the invagination of the bottle cells, followed by the coordinated involution of the mesoderm and the epiboly of the ectoderm. Vegetal rota- tion plays a significant role in directing the involution. 10. In the presence of BMP inhibitors, 11. In the head region, an additional set of proteins (Cerbenus 12. Wrt signalng cases a gradient ofpoaterin alog teat neural tissue. The action of BMP on causes them to become epidermis. ectodermal cells form ectodermal cells 3. The driving forces for ectodermal epiboly and the con- vergent extension of the mesoderm are the intercalation events in which several tissue layers merge. Fibronectin plays a critical role in enabling the mesodermal cells to migrate into the embryo The dorsal lip of the blastopore forms the organizer tissue of the amphibian gastrula. This tissue dorsalizes the ecto- derm, transforming it into neural tissue, and it transforms ventral mesoderm into lateral and dorsal mesoderm. Frzb, Dickkopf, Tiki) blocks the Wnt signal from the venta and lateral mesoderm. rior-posterior acis of the neural plate. This graded signaing appears to specity the regionaization of the neural tube 4· 13. Insulin-ike growth factors (GFs) help transform the neura tube into anterior (forebrain) tissue. 5. The organizer consists of pharyngeal endoderm, head 14. The left-right axis appears to be initiated by the activation of a Nodal protein solely on the left side of the embryo.In Xenopus, as in other vertebrates, Nodal protein activates mesoderm, notochord, and dorsal blastopore lp tissues organizer functions by secreting proteins (Noggin, Chordin, and Follistatin) that block the BMP signal that would otherwise ventralize the mesoderm and activate the epidermal genes in the ectoderm. expression of pit2, which is critical in distinguishing lent- sidedness from right-sidedness in the heart and gut tubes 15. Cleavage in fish is meroblastic. The deep cells of the blastoderm form between the yolk syncytial layer and the enveloping layer. These deep cells migrate over the top of the yolk, forming the hypoblast and epiblast layers 6. Dorsal-ventral specification begins with maternal mes- sages and proteins stored in the vegetal cytoplasm. These include Nodal-like paracrine factors, transcription factors (such as wgn, and agents that protect -catern from 16·Onthe future dorsal side, the hypoblast and epilast inter. calate to form the embryonic shield, a structure homolo- gous to the amphibian organizer. Transplantation of the embryonic shield into the ventral side of another embryo will cause a second embryonic axis to form 7. The organizer is itself induced by the Nieuwkoop center located in the dorsalmost vegetal cells. This center is formed by the translocation of the Disheveled protein and Wint 1 1 tothe dorsal side of the egg to stabilize -catenin the dorsal cells of the embryo. The Nieuwkoop center is formed by the accumulation of -catenin, which can complex with TCt3 to form a transcrip- 17. In both amphibians and fish, neural ectoderm is permited to form where the BMP-mediated induction of epidermal issue s prevented. The fish embryonic shield, liked the amphibin dorsal blastopore lp. secretes the BMP antagonists, Lke the amphibian organizer, the shield receives its abltes by being induced by B-catenin and by underlying endoderma ceis expressing Nodal-related paracrine factors. 8. tion factor complex that can acihate the transcription of the siamois and twin genes on the dorsal side of the embryo. 9. The Siamois and Twin proteins collaborate with activated Smad2 transcription factors generated by the TGF-BExplanation / Answer
Based on the given Snapchat summary,this is totally about the Embryonic Development,it's mechanism and regulation in vertebrates(amphibians,fish,birds and mammals).
1.Major theme in case 1st -Embryonic development or post fertilization development in amphibian and fish,it's mechanism and the regulation.Example-Amphibian(frog) and fish (Chondrichthyes and osteichthyes fishes).
2.Major theme in case 2nd is -Embryonic development or post fertilization development in birds and mammals,it's mechanism and it's regulation,genes involved etc.Example -Birds(Pigeon )and mammals like human,rat etc show these type of -Embryonic Development.
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