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Size DOES Matter!
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HHMI Geneticist and his mouse and fly. Size Does Matter! HHMI Geneticist Vs. Dinosaur
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Size Feature Is One of the Fundamental Characters of Living Organisms Fruit flies: ~1 mm 1 ~1 mg 1 Mice: ~10 cm 10 2 ~10 g 10 4 Humans: ~1 m 10 4 ~100 kg 10 8 Dinosaurs: ~10 m 10 5 ~10 MT 10 10
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Size DOES matter!
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Biological Significance of Size Features Bone/Body Mass The Length of the Legs Roots/Trunk Heart/Body Mass Proportionality Ratio of Organ Sizes The Golden Ratio & Fibonacci Series
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Phi = A/B = B/C = 1.618… P = B/A = C/B = 0.618… Phi: the Golden Ratio and Fibonacci Series BC A http://goldennumber.net
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Human Beauty Is Based on Phi
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Animal Body Is Based on Phi
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Fibonacci Series in Plants
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Biological Significance of Size Features Mating Segregation Predator/Prey Enlarged Roots/Store Water Longer Fish Swims Faster Size & Function Egg Sizes/Maturation Time Body Size/Surface-Mass/Body Temperature/ Metabolic Rates/Longevity Fixed Adult Size/Continue Growing Leave Sizes/?
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Evolution Question: Why Did Animals Become Bigger Early And Are Now Getting Smaller? O2 Food Supply Land Area
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Size Property Is Intrinsic to an Organ Primodium Graft Exchange Amblystoma tigrinum A. punctatum Twitty and Schwind, 1928 Proc. Soc. Exper. Bio. Med. 25:686
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Size Control Mechanism
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Implication of Regeneration
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Wing Size Is Unchanged When Pattern Is Disrupted Wild Type col Mutant Vervoort, M. et al., 1999
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Overexpression of E2F Increases Cell Numbers, but Does Not Change Wing Size Neufeld T. et al., 1998
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What Determines the Sizes of the Organs/Organisms? What Genes? Genes!
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Identify Tumor Suppressors in Mosaic Flies RB + - - Xu et al. 1995 Development Tumors? / + /
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Xu et al., 1995, Development Tumors in Drosophila Eye
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Xu et al., 1995, Development
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Lats Mutants Deregulate Organ Size Xu et al. 1995 Development Tao et al. 1999 Nature Genetics
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Identify overgrowth mutants by comparing twin-spot clones Xu et al., 1995 Development W + W + Replication W + W + Segregation W + W + W W Mutant Cell + + Wild Type Twin-spot Cell
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Identify Overgrowth Mutants by Comparing the Sizes of Twin Clones Xu et al. 1995 Development -/- +/+
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Tsc1, Tsc2, and PTEN Mutations Deregulate Organ Size Potter et al. Cell 2001
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Size DOES matter!
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Lats Homologs Function as TS in Flies and Mice St John et al. 1999 Nature Genetics
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Tumorigenesis Requires Deregulation of Size-Control Mechanism Tumor development requires increasing total mass Multiple tumor suppressors and oncogenes affect Mechanisms of size control Molecules participating in size-control could be targets for anti-cancer drugs Potter and Xu 2001
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S6k Tor Akt (PKB) InR PI3K Tsc1Tsc2 Active Potter et al. Cell 2001 Potter et al. Nat Cell Bio 2002 Inoki et al. G & D 2003 PTEN Rapamycin S6K Tor Inactive Tsc1 PP Tsc2 TSC Pathway Provides A Basis for Therapeutic Intervention Rheb
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Clinical Trails for TSC and LAM 2003 Kwiatkowski, Harvard; Yeung, U of W Clinical trails 2003.4 US: Drs. McCormack, Franz, Bissler England: Drs. Simpson and Kingswood Germany: Dr. Weinke Pathway conserved, S6K activated in patients TSC pathway and drug target TSC animal trial 2002-2003 Many groups 2001,2002 Potter & Xu
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How Organisms Measure Size?
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Drosophila TSC genes affect cell size, but not ploidy Potter et al Cell 2001
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Wild-Type Organisms build structures by measuring physical distance or cell number? Distance Cell Number Tom Ni, Undergrad
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