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Unformatted text preview: BICD 130 Embryos, Genes, and Development Review Session for Final Exam Sunday March 19 1-3 PM PCYNH 109 "Nothing in biology makes sense except in the light of evolution"
Theodosius Dobzhansky The diploblasts (Radiata) are distant relatives of the triploblasts (Bilateria) Cnidaria: jellyfish, sea anemones, corals, hydroids The cnidarian Hydra is a diploblast Mouse Fly Hydra Conservation of Suppressor of Hairless protein sequence over more than 600 million years of evolution ------------------------MPSGFPQSPRTSPRAR----PKTRITGALP-----------MDYSEGLSAEERPAHAPSAGKFGER MKSYSQFNLNAAAPPAIAYETTVVNPNGSPLDPHQQQQQQSQDMPHFGLPGPQPPSSQQQQQQLQVHHQQQQQQQQQQQQQQHQQQMQMS --------------------MEINQCDSFSYHPYDFIGIT-KDLPHLIFNPGVESS---------YIYHTVQPENCLYQSVNHINQFEQA PPP---------KRLTREAMRNYLKERGDQTVLILHAKVAQKSYGNEKRFFCPPPCVYLMGSGWKKKKEQMERDGCSEQESQPCAFIGIG LLPGPYRPHIEEKKLTRDAMEKYMRERNDMVIVILHAKVAQKSYGNEKRFFCPPPCIYLFGSGWRRRYEEMLQQGEGEQGAQLCAFIGIG P-----------RKLTASNMNRYLKERDHYIVTILHAKVAQKSYGNEKRFFCPPPCVYLSGKGWKKRKEEK---GESCQ-LYPFVFTNIG NSDQ-EMQQLNLEGKN---YCTAKTLYISDSDKRKHFMLSVKMFYGNSDDIGVFLSKRIKVISKPSKKKQSLKNADLCIASGTKVALFNR SSDQ-DMQQLDLNGKQ---YCAAKTLFISDSDKRKHFMLSVKMFYGNGHDIGVFNSKRIKVISKPSKKKQSLKNADLCIASGTNVALFNR SPDQPGFQQYDINEKENIAFCSAKSMYISDVDKRKNFIIHSQLIFQDGKNLGIFDSKRIKVISKPSKKKQSSKNTELCISSNSNVALFNR LRSQTVSTRYLHVEGGNFHASSQQWGAFYIHLLDDDESEGEEFTVRDGYIHYGQTVKLVCSVTGMALPRLIIRKVDKQTALLDADDPVSQ LRSQTVSTRYLHVENGHFHASSTQWGAFTIHLLDDNESESEEFQVRDGYIHYGATVKLVCSVTGMALPRLIIRKVDKQMALLEADDPVSQ LRSQTVSTRYLHVENDNFIASSLQWGFLSIHLCNDNEPDGEEVTVNEGIVHYGQTVKLVFVKTNLATPMMIIRKVDKQTVVLDADDPVSQ LHKCAFYLKDTERMYLCLSQERIIQFQATPCPKEQNKEMINDGASWTIISTDKAEYTFYEGMGPVLAPVTPVPVVESLQLNGGGDVAMLE LHKCAFYMKDTDRMYLCLSQEKIIQFQATPCPKEPNKEMINDGACWTIISTDKAEYQFYEGMGPVASPVTPVPIVNSLNLNGGGDVAMLE LHKVAFYVKGTNRSYLSINQEKVIMFQASPCSKDPKRDVISDAASWTIISADKSTYRFCEGAGPVQSKIAPVPFVSNLHLTGGGDVVTME LTGQNFTPNLRVWFGDVEAETMYRCGESMLCVVPDISAFREGWRWVRQPVQVPVTLVRNDGVIYSTSLTFTYTPEPGPRPHC-SAAGAIL LSGDNFTPHLQVWFGDVEAETMYRCTETLLCVVPEISQFRGEWLWVRQPTQVPISLVRNDGIIYATGLTFTYTPEPGPRPHCNTQAEDVM VNGEKFTSNLKVWFADVEAETMYRSSETLICLVPDVSLFKDRWKYKQSDFSVPVSLVRDDGVIYPTDCTFTFTPEL----YFTDEAGLHE RANSSQVPSNESNTNSEGNYTNASTNSTS-----------VTSSTATVVS-------RARQNNNNNNITSISNNNNSNNAGSPAAGGGLQQQQQQHQALPSISEVQWNSHGSGLS RISRYVTPTKLL---------------------------------------------- Par Towb Nature 407: 186-189 (2000) Evolutionary conservation of Wnt pathway function in axis formation Hydra -catenin can induce a complete second axis in the Xenopus embryo Evolutionary conservation of BMP signaling in D/V axis formation Evolutionary conservation of developmental regulatory proteins and their functions Evolutionary conservation of developmental regulatory proteins and their functions Drosophila wing The Hedgehog signaling pathway has been co-opted for the formation of eyespots on butterfly wings Bicyclus wing Eyespot color patterns in the butterfly Bicyclus anynana correlate with zones of transcription factor expression Distalless Spalt Engrailed merge Wild type Changes in eyespot color patterns correlate with changes in transcription factor expression
Goldeneye Engrailed Spalt Eyespot size may reflect the strength (range) of signaling from the focus Changes in eyespot color patterns may reflect changes in response thresholds What are the major mechanisms underlying the appearance of developmental novelty during evolution? How might changes in Hox gene function lead to changes in animal body plan? etc.... Evolution of Hox gene clusters Amphioxus is a cephalochordate Most recent view of Hox cluster evolution Changes in body plan due to broad changes in Hox gene expression Changes in Hox gene expression underlie the loss of forelimbs in snakes Lack of Ubx and abdA expression leads to the appearance of feeding appendages in thoracic segments of crustaceans Ubx/adbA
maxilliped Differences in larval and adult morphology of flies and butterflies The limb-promoting gene Distalless is expressed in abdominal prolegs of the butterfly larva Why doesn t Ubx and abdA expression repress abdominal proleg development? Ubx/abdA Distalless Changes in Hox target genes appear to underlie the development of wings in T3 Ubx and abdA, insect abdomen genes The difference in limb repression capacity of fly and shrimp Ubx maps to the Cterminus of the protein Limb repression Ronshaugen et al. (2002) Nature 415: 914-917 The C-terminus of fly Ubx is permissive for limb repression; the C-terminus of crustacean Ubx is inhibitory Ser/Thr residues, particularly one in a CKII phosphorylation site, inhibit the limb repression function of crustacean Ubx
Limb rep CKII consensus Model for evolution of the Ubx protein leading to the hexapod body plan Selective loss of Pitx1 expression underlies pelvic reduction in freshwater sticklebacks Shapiro et al. (2004). Nature 428: 717-723 A novel cis-regulatory element in the yellow gene underlies the dark wing spot of Drosophila biarmipes Adult male wing Yellow protein D. melanogaster D. biarmipes D. pseudoobscura Gompel et al. (2005). Nature 433: 481-487 Insect and vertebrate limbs seem analogous, not homologous (related by descent from a common ancestor) Insect: chitin, no inner skeleton; formed by eversion of imaginal discs Vertebrate: bony endoskeleton; formed by interaction of ectoderm and mesoderm Does evolutionary conservation of pathway utilization imply homology? Does evolutionary conservation of pathway utilization imply homology? ...
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