Twist mesoderm determinant Germ band Germ band ectodermal and mesodermal cells

Twist mesoderm determinant germ band germ band

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Twist: mesoderm determinant Germ band Germ band: ectodermal and mesodermal cells that build the trunk of the embryo Mesoderm Endoderm Germ band extension and retraction
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Figure 9.6 Axis formation in Drosophila
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Genetics --- classes of recessive mutations vg + /vg X vg + /vg vg/vg; small wing (1) vg + /vg: normal wing (2) vg + /vg + : normal wing (1) hh + /hh X hh + /hh (hh: hedgehog) hh/hh; dead embryo (1) hh + /hh: normal embryo (2) hh + /hh + : normal embryo (1) Viable and visible mutation Lethal mutation with defective structure
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Genetics --- classes of recessive mutations bcd + /bcd X bcd + /bcd (bcd: bicoid) bcd/bcd: normal embryo (1) bcd + /bcd: normal embryo (2) bcd + /bcd + : normal embryo (1) Why is bcd a mutant? Adult mutant female bcd/bcd (F) X bcd + /bcd + (M) All dead embryos (bcd/bcd + ) The bcd female is sterile. Maternal effect mutation (gene) Something important happens during oogenesis.
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Axis formation during oogenesis Gurken-Torpedo interaction Germ line cells (oocyte) vs. somatic cells (follicle cells) D-V axis formation --- Toll pathway (maternal effect genes) Note: Toll pathway in Drosophila is homologous to the Human NF-kB pathway. A-P axis formation --- Maternal effect genes, Gap genes, pair-rule genes, segment polarity genes Foundation of body axes is established during oogenesis.
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