BIOL 430 2010 lecture 13 handout 6 slides

BIOL 430 2010 lecture 13 handout 6 slides - How do the...

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1 BIOL 430 Lecture 13 February 9 th 2010 Segment polarity genes and compartments BIOL 430 Molecular Genetics of Development 2010 Dr. Ian Chin-Sang (www.chin-sang.ca) Segmentation : selector and homeotic genes How do the final segments boundaries of the larva and adult become established? Answer: The segment polarity genes mutations in these genes cause defects in the A P What is meant by segment polarity? BIOL 430 Molecular Genetics of Development 2010 Dr. Ian Chin-Sang (www.chin-sang.ca) mutations in these genes cause defects in the A-P segment polarity i.e. mirror-image,or tandem duplications of either anterior or posterior parts. segment polarity genes act during the cellular blastoderm as opposed to the syncytium Engrailed is a segment polarity gene that is expressed in the anterior region of each parasegment. (It is also a selector gene that confers particular identity on a region or regions by controlling the activity of other genes) BIOL 430 Molecular Genetics of Development 2010 Dr. Ian Chin-Sang (www.chin-sang.ca) 2 1 a a pp eve en Pair-rule Segment polarity BIOL 430 Molecular Genetics of Development 2010 Dr. Ian Chin-Sang (www.chin-sang.ca) Engrailed expression (at germ band extension stage) Fig. 2.32 The Engrailed pattern is confined to a few cells in the anterior region of the parasegment and is due to the activation of the pair rule genes (even-skipped and fushi tarazu) Ftz =even Eve =odd Boundaries Get sharper BIOL 430 Molecular Genetics of Development 2010 Dr. Ian Chin-Sang (www.chin-sang.ca) En = anterior of All parasegments Fig. 2.33 6 5 a a eve (odd) en Pair-rule 4 3 a a 2 1 a a ftz (even) The pair-rule genes regulate segment polarity gene expression BIOL 430 Molecular Genetics of Development 2010 Dr. Ian Chin-Sang (www.chin-sang.ca) Segment polarity a a a a a a a p a p a p fushi tarazu mutant (too few segments) en expression is lost from even numbered parasegments leading to fewer segments
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2 engrailed is required for the maintenance of the posterior compartment and formation of the A-P boundary BIOL 430 Molecular Genetics of Development 2010 Dr. Ian Chin-Sang (www.chin-sang.ca) Remember that engrail expression ends up being in the Posterior compartment of the larva.
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This note was uploaded on 12/06/2011 for the course BIOL 430 taught by Professor Dr.ianchin-sang during the Winter '10 term at Queens University.

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BIOL 430 2010 lecture 13 handout 6 slides - How do the...

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