BIOE 20C Lecture Notes - Lecture 9: Limb Bud, Pax6, Molecular Evolution
6 Apr 2018
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Week 4 thursday lecture notes both mouse limbs and fish fins form from limb buds in embryos. Hoxd-11 and shh are both genes that regulate the direction of limb bud growth. Mouse limb initially similar but there is additional expression in head-tail axis later in fish fin only express hoxd-11 and shh in rear of limb bud and early development. One example eyes in insects and mammals eyeless gene in flies: switch to turn on genes that form eyes in flies, normal gene-normal eye, mutation forms eyeless flies. Pax-6 gene in mice: switch to turn on genes that forms eyes in mice, normal gene-normal eye, mutation forms small eyes in mice. Experiment: transplant tissue expressing eyeless gene to different part of body. Experiment: insert mouse pax-6 gene in fly genome. Result: mouse gene causes fly eye to grow in transplant area. Conclusion: eyeless and pax-6 genes are orthologs.
