V动物身体图式的模式建成Ippt课件

1、Developmental BiologyPatterning the body plan in animals-invertebratesPattern formation is one of the essential principles of development (I)n Morphogenesis is the developmental process of forming the tissue, organ and embryo. For example, embryogenesis is the process by which the embryo with a well

2、-ordered spatial arrangements of differentiated tissues and organs is formed. n Morphogenesis involves a combination of cell proliferation, differentiation, movement, adhesion and induction. However, the question of how this morphogenesis happens is really about pattern formation模式建成）.n Pattern form

3、ation is the process of developing a programme or blueprint for constructing the embryos. It initially involves laying down the overall body plan （身体图式） -defining the main body axes of the embryo so that the head (anterior) and tail (posterior) ends, and the back (dorsal) and underside (ventral) are

4、 specified.n The main body axes are the antero-posterior axis, which runs from the head to the tail, and the dorso-ventral axis, running from the back to the belly. These two axes are at right angles to each other.n While the body axes are specified, the embryo is patterned along both the antero-pos

5、terior, and dorso-ventral axes. So, pattern formation is basically comprised of the body axes specification/formation, and patterning along the body axes.n Different species specify the body axes at different times, using different mechanisms. Pattern formation is one of the essential principles of

6、development (II)Patterning the body plan in animals1 Development of the Drosophila body plan1.1 Specification of the antero-posterior and dorso-ventral axis in Drosophila oocyte1.2 Setting up the body axes in Drosophila1.3 Patterning the Drosophila embryo2 Patterning the vertebrate body plan2.1 Sett

7、ing up the body axes in amphibians (Xenopus)2.2 Somite formation and antero-posterior patterning2.3 Patterning the vertebrate nervous systemPatterning the body plan in animals1 Development of the Drosophila body plan1.1 Specification of the antero-posterior and dorso-ventral axis in Drosophila oocyt

8、e1.2 Setting up the body axes in Drosophila1.3 Patterning the Drosophila embryo2 Patterning the vertebrate body plan2.1 Setting up the body axes in amphibians (Xenopus)2.2 Somite formation and antero-posterior patterning2.3 Patterning the vertebrate nervous systemPatterning of the Drosophila embryo

9、along the body axes The body axes are specified in the developing oocyte The body axes are fully established in the very early embryo As the development proceeds, the embryo is patterned along the two axes: that is to divide the embryo into distinct regions along both axesPatterning the body plan in

10、 animals1 Development of the Drosophila body plan1.1 Specification of the antero-posterior and dorso-ventral axis in Drosophila oocyte1.2 Setting up the body axes in Drosophila1.3 Patterning the Drosophila embryo2 Patterning the vertebrate body plan2.1 Setting up the body axes in amphibians (Xenopus

11、)2.2 Somite formation and antero-posterior patterning2.3 Patterning the vertebrate nervous systemThe Drosophila female reproductive systemEgg development in DrosophilaEgg development in DrosophilaOverview of the Drosophila oogenesisDrosophila body axes are specified in the oocyte during oogenesisn T

12、he antero-posterior axis of the Drosophila oocyte is specified by interactions of the oocyte with the posterior follicle cells during mid-oogenesis.n The dorso-ventral axis of the oocyte is specified by movement of the oocyte nucleus followed by signaling between oocyte and the surrounding follicle

13、cells(卵泡细胞). Mechanisms underlying specification of the antero-posterior and dorso-ventral axes in Drosophila oocyte n When a follicle/egg chamber leaves the germarium, the oocyte is always found at the most posterior position in the germ-line cyst. This posterior positioning of the oocyte plays a k

14、ey role in specification of the antero-posterior and dorso-ventral axes in the oocyte during mid-oogenesis.n The antero-posterior and dorso-ventral axes of the oocyte are specified during mid-oogenesis through reciprocal signaling between the oocyte and the surrounding epithelial follicle cells.The

15、posterior positioning of the oocyte in the nascent egg chamber play a key role in specification of the body axes in the oocyteA Notch/Delta and JAK/Stat-dependent relay model for the oocyte positioning in the posterior of egg chambers Germline cells of older follicleInduction of anterior polar cells

16、Induction of stalkUpregulation of DE-cadherin in the posterior follicle cells and the oocyte of younger folliclePosterior oocyte localization in younger follicleNotch/DeltaJAK/StatNotch/Delta The body axes are specified during mid-oogenesis through the reciprocal signaling between the oocyte and the

17、 surrounding follicle cells The PFCs send back a unknown signal to oocyteActivation of protein kinase A in oocyteMicrotubule cytoskeleton reorganizationDynein moves the bicoid mRNA to the anterior end of the eggKinesin I moves the oskar mRNA to the posterior endPatterning the body plan in animals1 D

18、evelopment of the Drosophila body plan1.1 Specification of the antero-posterior and dorso-ventral axis in Drosophila oocyte1.2 Setting up the body axes in Drosophila1.3 Patterning the Drosophila embryo2 Patterning the vertebrate body plan2.1 Setting up the body axes in amphibians (Xenopus)2.2 Somite

19、 formation and antero-posterior patterning2.3 Patterning the vertebrate nervous system Setting up the Drosophila body axes n The body axes are alreadly specified in the Drosophila egg, and become fully established and patterned in the very early embryo while it is still in the syncytial blastoderm合胞

20、体胚盘）. n Organization along the antero-posterior and dorso-ventral axes of the early embryo develops more or less simultaneously, but is set up by independent mechanisms and by different sets of genes in each axis. n Patterning of the Drosophila embryo occurs along the two body axes: that is to divid

21、e the embryo into distinct regions along both the antero-posterior and dorso-ventral axes.Three classes of maternal genes are involved in setting up the antero-posterior axis in the very early embryo (I) n At mid-oogenesis, the antero-posterior axis is specified in the egg by the localized distribut

22、ion of the maternal gene mRNAs, such as bicoid mRNA in the anterior, and oskar mRNA in the posterior.n Upon fertilization, these mRNAs can be translated into proteins. At the anterior pole, bicoid mRNA is translated into Bicoid protein, which diffuses throughout the blastoderm and forms a concentrat

23、ion gradient that is highest at the anterior. At the posterior pole, the nanos mRNA in association with Oskar protein is translated into Nanos protein, forming a gradient that is highest at the posterior. Thus, the gradients of these maternal proteins (Bicoid and Nanos) determine the antero-posterio

24、r axis in the early embryo.Bicoid protein forms an antero-posterior concentration gradient in the early embryoTop panel: the mRNA is visualized by in situ hybridizationMiddle panel: the Bicoid protein is stained with a labeled antibodyThe bicoid gene is necessary for the development of the anterior

25、structuresThe bicoid gene is necessary for the development of the anterior structuresMutations in nanos gene lead to lacking a large part of the posterior region ( abodomen)A model of antero-posterior axis generated by the Drosophila maternal effect genesn In addition to Bicoid and Nanos proteins, t

26、here is third set of maternal genes whose proteins generate the extremities of the antero-posterior axis. A critical gene here appears to be torso, a gene encoding a receptor tyrosine kinase (RTK). Three classes of maternal genes are involved in setting up the antero-posterior axis in the very early

27、 embryo (II) Mutations in torso gene lead to lacking the structures at the extreme ends of the antero-posterior axis, acron and telson n While and after the antero-posterior and dorso-ventral axes are established in the very early embryo, patterning of the embryo occurs along the body axes.n Along t

28、he antero-posterior axis the embryo becomes divided into several broad regions, which will become the head, thorax, and abdomen of the larva and adult. Typically, the thorax and abdomen become divided into segments as the embryo develops. Each segment has its own unique character, as revealed by its

29、 external cuticular structures. The embryo is patterned along the AP axis through the control of different sets of zygotic gene expression by the maternal genes The relationship between parasegments and segments in the early embryo, late embryo, and adult flyT1: legs onlyT2: wings and legsT3: halter

30、es and legsComparison of larval and adult segmentation in DrosophilaThe three thoracic segments can be distinguished by their appendagesThe Nobel prize in physiology & medicine in 2019 was awarded to 3 developmental biologists for their work in the genetic control of the early embryonic developm

31、ent in DrosophilaChristiane Nsslein-Volhard Eric F. Wieschaus Edward B. Lewis The sequential expression of different sets of zygotic genes patterns the body plan along the AP axisSegment polarity genesHomeotic selector genesBicoid-anterior morphogen(The protein gradient from yellow to red) Hunchback

32、/Kruppel-gap gene protein(Orange: the domain of Hunchback expression only; Green: the domain of Kruppel expression; Yellow: overlap between Hunchback and Kruppel) Fushi Tarazu-pair-rule gene proteinEngrailed-segment polarity gene protein The temporal and spatial expression of those maternal and zygo

33、tic genes controls the patterning of the embryo along the AP axisSpecification of the identity (characteristic strucutre) of each segment is accomplished by the homeotic selector genesThe Antennapedia complexlab and Dfd-the head segmentsScr and Antp- the thoracic segmentsThe Bithorax complexUbx - th

34、e third thoracic segment AbdA and AbdB-the abdominal segmentsLoss-of-function mutations in the Ultrabithorax gene can transform the 3rd thoracic segment into another 2nd thoracic segment, producing a four-winged fly Ectopic expression of Antennapedia gene in the head leads to legs rather than antenn

35、ae growing out of the head socketsWild typeMutant1st and 2nd thoracic segments3rd thoracic segments and abdominal segments The body axes are specified during mid-oogenesis through the reciprocal signaling between the oocyte and the surrounding follicle cells The gurken mRNA and its protein are local

36、ized between the oocyte and the dorsal follicle cells of the ovaryThe gurken mRNAThe Gurken proteinThe Gurken proteinThe actinSchematic representation of the generation of dorsal-ventral axis in Drosophila embryoPipe: a heparan sulfate sulfotransferase; Pelle: a protein kinasePipe expression only in

37、 ventral follicle cellsActivation of Toll signaling pathway in ventral side of early embryosTranslocation of Dorsal protein to nucleus in the ventral sideFormation of the nuclear gradient of Dorsal along the dorsal-ventral axisRole of the Toll signaling pathway in patterning of the embryos along the

38、 DV axisThe dorso-ventral axis is established in early embryo by the intranuclear concentration gradient of Dorsal protein from the ventral to dorsal The embryo is patterned along the DV axis through regulating the zygotic gene expression by the nuclear gradient of Dorsal proteinn The dorso-ventral

39、axis of the embryo becomes divided into four distinct regions early in embryogenesis: from ventral to dorsal there are the mesoderm, which will form muscles and other internal connective tissues; the ventral ectoderm, which gives rise to the larval nervous system and is thus also called the neurogen

40、ic ectoderm or neurectoderm; the dorsal ectoderm, which gives rise to the larval epidermis; and the amnioserosa, which gives rise to an extra-embryonic membrane on the dorsal side of the embryo.n The gradient of Dorsal protein in the nuclei subdivides the embryo along the dorso-ventral axis through

41、regulating the zygotic gene expression.Patterning of the Drosophila embryo The body axes are fully established in the very early embryo As the development proceeds, the embryo is patterned along the two axes: that is to divide the embryo into distinct regions along both axes The genetic control of p

42、atterning of the embryo along the DV axis by the gradient of Dorsal protein in the nuclusChange in the nuclear gradient of Dorsal protein can cause dorsalization or ventralization of the embryoLoss-of-function mutations in gene cactus cause ventralization of the larvaeThe ventral denticle belts in c

43、uticle preparation of the wild type embryoLoss-of-function mutations in gene cactus cause ventralization of the larvaeThe ventral denticle belts in cuticle preparation of the wild type embryoVentralization phenotype in cactus mutant embryosSchematic representation of the generation of dorsal-ventral

44、 axis in Drosophila embryoThe snake mutant eggs develop into the dorsalized larvaeThe mutant larva consisting entirely of dorsal cellsRescue of the dorsalization phenotype in larvae developed from snake mutant eggs that received injection of mRNA from wild-type eggsLoss of function mutations in lgl

45、produce a lethal malignant tumor-like phenotype in DrosophilaDe Lorenzo et al, 2019lethal(2)giant larvae (lgl)The absence of lgl gene function blocks the egg development at certain stages Fused egg chambers Multilaywered accumulation of follicular cells at both extremities of egg chambersThe questio

46、n remains to be addressedHow does Lgl function in Drosophila oogenesis?Mutations in lgl cause oocyte mispositioning in the egg chamber a-OrbWTMutations in lgl cause oocyte mispositioning in the egg chamber a-OrbWTlglts3/lgl4The germline lgl activity is not essential for the posterior localization of

47、 the oocyte in the egg chambera-Orblgl4 FRT cloneLgl is required in the follicle cells to regulate the correct positioning of the oocyte in the egg chambera-Orblgl4 FRT cloneCoincidence between the oocyte mispositioning and the egg chamber fusions was observed in lgl mutantsa-Orblglts3/lgl4Coinciden

48、ce between the oocyte mispositioning and the egg chamber fusions was observed in lgl mutantsa-Orblglts3/lgl4lgl4 FRT cloneLgl is required for the stalk cell differentiation linked to the oocyte positioning in the anterior adjacent egg chambera-Orba-BibWTLgl is required for the stalk cell differentia

49、tion linked to the oocyte positioning in the anterior adjacent egg chambera-Orba-Biba-Orba-BibWTlgl4 FRT cloneLgl is required for the stalk cell differentiation linked to the oocyte positioning in the anterior adjacent egg chamberAnti-b-GalWTlgl4 FRT clone93F reporter93F reporterLgl is required for

50、the initial positioning of the oocyte, rather just for its maintenance at the posterior of the developing egg chambersa-OrbWTLgl is required for the initial positioning of the oocyte, rather just for its maintenance at the posterior of the developing egg chambersa-OrbWTlglts3/lgl4Lgl is required for

51、 the initial positioning of the oocyte, rather just for its maintenance at the posterior of the developing egg chambersa-Orblglts3/lgl4WTlgl4 FRT cloneLgl functions in the oocyte positioning by affecting the DE-cadherin mediated adhesion between oocyte and posterior follicle cellsa-Arma-EglWTLgl fun

52、ctions in the oocyte positioning by affecting the DE-cadherin mediated adhesion between oocyte and posterior follicle cellsa-Arma-EglWTlgl4 FRT cloneSummary (I)Lgl is required for the establishment of the initial AP asymmetry. Loss-of-function mutations in lgl cause mispositioning of the oocyte in t

53、he anterior adjacent one of the fused egg chambers, due to lack of the stalk differentiation.Lgl is required for the formation of the oocyte polarity along the anteroposterior (AP) axis at mid-oogenesisa-StaufenWTLgl is required for the formation of the oocyte polarity along the anteroposterior (AP)

54、 axis at mid-oogenesisa-StaufenWTlgl4 FRT cloneLgl is required for the formation of the oocyte polarity along the anteroposterior (AP) axis at mid-oogenesisa-Staufenlgl4 FRT cloneWTlgl4 FRT cloneLgl is required for the formation of the oocyte polarity along the dorsoventral (DV) axis at mid-oogenesisa-GurkenWTLgl is required for the formation of the oocyte polarity along the dorsoventral (DV) axis at mid-oogenesisa-GurkenWTlglts3/lgl4Lgl is required for the formation of the oocyte polarity along the do