MCBl41 DevelopmentalBiology Lecture1 February20,2014
Middle third of the course: Early developmentof vertebratesfrom the oogonium to the late neurula stage. ProfessorJohn Gerhart,395 LSA; [email protected]. Office hours: TBA Lectureschedule and optionalreadings. Use Gilbert as a supplementand reference: DevelopmentalBiology, Tenth edition, 2014; [Ninth, 2010]; or (Eighth2006). Lecture1, Thursday, Feb 20. Chordates and vertebrates: defining traits, outline of amphibian developrnent6-1 2 ; [6-1 1 ] ; @2-a6;21 6-217 ; 722: 725-7 31 ; 742-7 44) Lecture2, Tuesday,Feb 25. Fate, competence, specification, determination. Discovery of Spemann'sorganizer. 19-23; 107-113,241-245,252-255; t19-21; 112-113; 241-244;255-2561, (10-13; 25-31; 57 -62. 304-306). Lecture3, Thursday, Feb 27 . Cytoplasmiclocalizations, cortical rotation, and axis formation in the amphibianegg 90-91,2422-244; [92-9.3.242-2441; (81-83; 136; 153-158;615-619; 291-294;302-310) Lecture4,Tuesday, Mar4. Endo-mesoderminduction 92-93,256-262; [9a-95; 257-2621; (155-158; 311-312). Lecture5, Thursday,Mar 6. Formationof Spemann'sorganizer 262-266; [261-263], (312-324). Lecture6, Tuesday,Mar 11.Gastrulation9,245-251;19;244-2521; (29;295-302). Lecture7, Thursday,Mar 13. Neural induction and neurulation 79-82, 266-270,336-227; [79-80; 263-272;336-3371 (312-324; 375-38 1 Lecture8, Tuesday,Mar 18. Chick development and extraembryonic development2S6-298; l2B7- 297; 480-4821;(336-3a8; 501 -503; 45). Lecture9, Thursday,Mar 20. Mammalian early development 298-311; [300-313]; (92-96; 348-368). SpringBreak March 24-28 Lecture1; Tuesday, Apr 1. ProfessorRichard Harland: Summary of amnioteand mammalian gastrulation,overview of organogenesis- materibl will not be on Midterm2. Midterm2: Thursday,Apr 3,11:10-12:30.Reviews at timeTBA
Final third of the course: late development of vertebrates-organogenesis, cytodifferentiation.Lecture notes and readingassignments will be postedlater. , (Lecturel,Tuesday, Apr 1. Summaryand overview-see above (Midterm2: Thursday,Apr 3 [seeabove]) r Lecture2, Tuesday,Apr 8. NeuralTube: induction, morphogenesis, pattern, differentiation. Lecture3, Thursday,Apr 10. Neuraltube continued Lecture4, Tuesday,Apr 15.Somite differentihtion Lecture5, Thursday,Apr'17. Neural crest and placodes. Lecture6, Tuesday,Apr 22. Muscle development Lecture7, Thursday,Apr 24. Limb development. Lecture8, Tuesday,Apr 29.Endodermal derivatives and kidney. Lecture9, Thursday,May 1. Summaryof organogenesis Reading/RevieWRecitationweek May 5-9. Prof.Harland will hold a 2-hourreview session prior to the finalexam. FinalExam: Final Exam Group 13 - Thursday,May 15,2014,8-1 1 am.
DATETRAITS (14 are the mainones). Chordates= vertebrates+ uiochordates+ cephalochordates(sie p. 3) 7 Ectoderm DORSAL DORSAL epidermis 1. Notoohord hollownerye cord (CNS) neuraltube 7. pituitary 6. somites Mesoderm E qE 9 E' tr u.l kidney lu F gonad F v) z o melom mouth (L 000 heart 4. post-analtail Endoderm 5. endostyle/thyroid.3. pharyngealapparatus ' gut (gillslits, pharyngeal arches and pouches) in gonad pharynx VENTRAL B.left-right differences in gut and VENTRAL gillpouches heartcoiling, and brain regions classesof the Chordatephylum Elght 2 Theadvar,rtages of each for studyingdevelomenl. 1. Cepf,Flochordates-amphioxus(lancelet) 1 genomedone. Basal chordate. Smallmarine chordate with notochord, dorsal hollow nerve cord, gill slits, CHARDATESAS METAZOA somites,and post-anal tail. DEUTEFOSTOMES 2. Urochordates-ascidians,larvaceans. 4 genomes done. Small, fast developing Chodates goo( Hemichordates larvawith chordaletraits. Good methods to introduceand express genes; Echinoderms lineagetracing. 3. Agnathans$awless fish)-lamprey, hagfish. 2 genomesdone. Basalvertebrate LOPHOTROCHOZOA withneural crest, peripheral nervous system, adaptive immune system. 14 phyla 4. Flsh(awed fish)- cartilaginous(sharks, rays, skates) and bony fish (ray linned Annelids, Mollusks, andsarcopterygian). 5 genomes done. Zebrafish are small, fast developing, Flatworms... goodgenetics and transgenesis. r 5. Amphlblans-anurans(frogs) and urodeles (salamanders, newts). 2 genomes ECDYSOZOA.. done.Eggs are big, robust; and easy to getand to inject;a centuryof 9 phyla experimentalwork. Transgenesis. mRNA knockdown. Arthrcpods, 6. Reptlles-allig-ators,lizards, turtles. Cleiodoic egg, elitraembryonic tissues. 1 Nematodes... genomedone. Largely unstudied. 7. Blrds-2 genorhesdone (chlcken, zebrafinch). Mammal-like development Cnidarians yet get. Ctenophorcs (epiblast,hypoblast, primitive streak), eggbigger and easier to Mammals-Monotrgrnes(echidna, platypus) 1 genomedone. Marsupials. Sponges ' 8. (kangaroo,opossum) 1 genornedone. Eutherians (mouse, rat, dog). 52 genornesdone. For mouse, good genetics, gene knockout, and transgenesis.
Phylogenetictree of the Ghordateclasses -l I B. mammals (t4 genomesdone). I monotremes(echidna, platypus) | marsupials(kangaroo, opossum) I amnioteancestor eutheria(human, mouse) invasionof dryland | cleidoicegg 7. birds (2 genomesdone) | AlIveftehra,'tes extraembryonicfibsues chicken,.quail,zebra tinch halveabout I genome 25,000genes, as tetrapodancestor 6. reptiles ( done) | do many other invasionof wetlands alligators I limbs snakes,tunles I bilatera,l Iizards anlmals.And I I mostof the t 5. amphibia( genomedone) genesare I | fr E frogs (Xenopus laevis) | > 5 siftr'lar ta those I satamanders in other anirnals. bony ftsh * ancestor l* t 4c. fish: sarcopterygian lH 0. iawedancestor coelacanth,lungfish predition, more m otiI e, | tr elaboratehead' > paired 4b. fish: ray finned (s senomesdone) | H ' senseorgans Pairedfins zebrafish, stickleback, medaka I qa, vertebrateancestor 4a. fish: cartilaginous I bone,verlebrae, neural cresl skafes, rays,sharks o pertpheralneruous sYstem I adaptiveimmune sYstem t ' genome o exPanded jawless I greater motilitY 3. fish 1t genomedone) | 4x genome inerease, I Iamprey,hagfish I I thengene ioss -| I u, (E o 't o a (J G' 2. urochordat€s genom"oon"I (EE o, 73 , F dorsal nervecord o () - ascidians,iarvaceans grllslits o a lE F post-analtail ! tt .c 1. cephatochordates( genomeaonq | tr somifes ur > I amphioxus millions of years from present - 600? 500 300 200 100 approx. 0.1 aa substitutions (depends on the specific protelns and lineage) XenoPus devel'oPment: [lFl |ts.*t - tGrey $ o.7 in Gilbert gthEd staset I I . Esg. -Aninrt ml€
Cleavage 1.3mm eomin diameter ,e Gastrula(seclionl Cortical rotation: secondaxis 1cell, 1 mg 360 min (6 hrS) /---Wswl '*"' Ferritizarion :"' U Newgene exPresslon ffiN 0 min Mesoderminducticn 1W .r.*;\$I tB [-ffi*[Spemann's Ooqenesis 10 hrs. . \v \lj'l ../ orqanlzer mRItAs localized, animal-vegetalaxis 20,000cells ,f6 \ / -- retgpg(e Bmonths-1year: I Adult Gastrulation sexual maturity Morphogenesis; |;;'."l 10!ocells j Neuralinduction 100grams (100,06Oxegg weight) and dorsalization by the organizer Metamorphosis(vegetarian to carnivore) 3 monthstrrv' Lr ,:' ,^a /@ Freesttdmrnlng ' 'e ' -. ' r n5 to 1oa cells ;'hdpole .r feeding,growth ]"- rrltgtolg 6lodem lulufe gtn - f;,";l hatching (sectionf (3daYs) f\ 72 hrs Cvtodifferentiation-'oig"nog"nesis i#-- loo,ooocells o*-_Histogenesisrr'---\= t7 -": {-o'-'' n€ural lolds
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bmp2I4l7 "H1'u bmp2l4l7 The tailh.rd stage is also called the pharyngula slage. lt is the earliest stage possessing all the main traits of the phylum, namely, notochord, apost.anattait,thatis,aphytotypicbodyplansypica|ofthephy|um). At this stage the hox genes and >20Oother "seleclor genes" are first expressed, making a dense map of gene expr€ssion domains covering the ootoderm, rnesderm, and endodermal layers of the body. Seleotor genes encode transcription factors or intercellularsignaling oomponents that s€lect what developrnent will subsoquenlly odcur in the domain of each. 4 FateMap of the early gastrulastage (Amphibian, Xenopus). Thisis worthlearning in somedetail. Five weeks from now, you willbe ableto explain why eachof the differentparts of the gastruladevelops the way it does,in termsof the maternalmRNAs it containedearlier and the inductivesignals it receivesin the nextstage. Why makea map of thisstage? lt hasall the organizationof the egg,though now cleavedto 10,000cells, yet it is fullyprepared to undergogastrulation and neurulation,two greatevents of morphogenesisthat will establish embryonic organization,with all the chordatetraits in place,an organizationvery differentfrom thatof the egg. To makea fatemgp. you need to be ab,teto placedye spots on theegg surface (e.9., nile blue) or injectdye into the interior(e.g., injected fluorescent dextran) at identifiablelocations. Cleavage stage embryoshave the animalpote, vegetalpole and grey crescent as landmarks. The early gastrula has the animalpqle, vegetal pole, and upper blastopore lip as landmarks.Every dye spot can be located accuratelyrelative to thethree landmarks, which are reliably the same in allembryos of thepopulation. Afterthe marked cleavage sJage embryo or markedgastrula develops to a tadpole,you can locate the dye spotin a specificpart of thetadpole and conclude that the cells you marked earlier have developed to that part.Then, you make a fatemap of thecleavage stage embryo or gastrulaby combiningdata on thefates inthe tadpole of allmarks at allpoints made earlier. blus la hlnclbrala
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