Fast-‐forward 14 years to 2013. Many other experiments in chickens and mice have convincedresearchersthat Pitx1 is definitely important for specifying that a limb bud develops into ahindlimb. Experiments haveshown that Pitx1 causes embryonic limb buds to express Tbx4,Hoxc10, and Hoxc11, all of which aretranscription factors specific to hindlimb development.Carlos Infante and colleagues (Infante, et al. 2013. Dev. Biol. 374:234-‐244) had a very specificquestion:Does the transcription factor Pitx1 bind to an enhancer that helps stimulatetranscription of the Tbx4gene?7. Use the diagram in Fig. 19.9 (Freeman et al 6e) to figure out where to put labels on the diagrambelow.The diagram is a schematic of mouse chromosome 11 which contains the Tbx4 gene(darkest shading).Potential binding sites for Pitx1 are found in hindlimb enhancer A andhindlimb enhancer B onchromosome 11. Add shading and labeling to show the spatialrelationship between the Tbx4 gene, itspromoter, and the likely location(s) of hindlimbenhancer regions.Infante et al. started by dissecting hindlimb buds from embryonic mice and putting the limb budsintoformalin. The formalin causes covalent bonds to form between DNA and any proteins (suchastranscription factors) interacting with enhancer or promoter sequences. Next, they dividedthe DNA
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- Fall '16
- Rebecca Darling
- DNA, limb development