DOCSLIB.ORG

Spemann's Organizer and Self- Regulation in Amphibian Embryos

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Spemann's Organizer and Self- Regulation in Amphibian Embryos PERSPECTIVES 34. Cortright, R. N., Collins, H. L., Rodenbaugh, D. W. 47. Paivio, A. Imagery and Verbal Processes (Holt, a salamander embryo was cut in half and & DiCarlo, S. E. Student retention of course content is Rinehart & Winston, New York, 1979). improved by collaborative-group testing. Am. J. 48. McClean, P. et al. Molecular and cellular biology transplanted into the flank of a host embryo, Physiol. Adv. Physiol. Educ. 27, 102–108 (2003). animations: development and impact on student each half could induce the formation of a 35. Dewey, J. How We Think: a Restatement of the Relation learning. Cell Biol. Educ. 4, 169–179 (2005). 3 of Reflective Thinking to the Educative Process (Revised 49. Blystone, R. V. & MacAlpine, B. WWW. cell biology complete limb, not just half a limb . The edn) (Houghton Mifflin Company, Boston, 1933). education: using the World Wide Web to develop a part of the embryo where this phenomenon 36. Piaget, J. The Psychology of the Child (Basic Books, new teaching topic. Cell Biol. Educ. 4, 105–111 New York, 1972). (2005). takes place was called the ‘self-differentiating 37. National Research Council. Science Teaching 50. Campbell, A. M. Public access for teaching genomics, morphogenetic field’. Reconsidered: A Handbook Ch. 4 (National Academy, proteomics, and bioinformatics. Cell Biol. Educ. 2, Washington DC, 1997). 98–111 (2003). Self-regulation, as defined by these early 38. Marrs, K. & Novak, G. Just-in-time teaching in biology: 51. Solomon, R. C. & Solomon, J. Up the University: experimental embryologists, is one of the creating an active learner classroom using the Recreating Higher Education in America (Addison- internet. Cell Biol. Educ. 3, 49–61 (2004). Wesely, Reading, 1993). most interesting and mysterious properties 39. Stith, B. Use of animation in teaching cell biology. 52. Vander, A. J. The Claude Bernard Distinguished of embryos. What are the molecular mecha- Cell Biol. Educ. 3, 181–188 (2004). Lecture. The excitement and challenge of teaching 40. Brown, J. S. Growing up digital: how the web changes physiology: shaping ourselves and the future. nisms that explain the intrinsic tendency of work, education, and the ways people learn. Change Am. J. Physiol. Adv. Physiol. Educ. 267, S3–S16 the embryo to regulate towards the whole? 32, 11–20 (2000). (1994). 41. Cuban, L. Oversold and Underused: Computers in 53. Haramati, A. Teaching physiology: filling a bucket or Here, I recount the story of the birth, decline Classroom (Harvard Univ., Cambridge, USA, 2001). lighting a fire? Physiologist 43, 117–121 (2000). and revival of amphibian experimental 42. Cates, W., Price, B. & Bodzin, A. Implementing 54. Wiggins, G. & McTighe, J. Understanding by Design technology-rich curricular materials: findings from the (Association for Supervision and Curriculum embryology, and how recent studies have Exploring Life project. Comput. Schools 20, 153–169 Development, Alexandria, 1998). uncovered a molecular pathway of interact- (2003). 55. Mintzes, J. J. & Wandersee, J. H. in Teaching Science 43. Kelly, H. Education for tomorrow needs innovation for Understanding: a Human Constructivist View ing extracellular proteins that explains how today. Carnegie Rep. 2, 44–45 (2003). (eds Mintzes, J. J., Wandersee, J. H. & Novak, J.) embryonic self-regulation works. This short 44. Gagné, R. M. The Conditions of Learning (Holt, Ch. 2 (Academic, San Diego, 1988). Rinehart & Winston, New York,1985). 56. Whitehead, A. The Aims of Education and Other review focuses on the advances made in 45. Rieber, L. P. Computers, Graphics, and Learning Essays (Macmillan, New York, 1929). amphibians, although great strides have also (Brown & Benchmark, Madison,1994). 46. Paivio, A. Dual coding theory: retrospect and current Competing interests statement been made in other model systems, such as status. Can. J. Psychol. 45, 255–287 (1991). The author declares no competing financial interests. the fruitfly (Drosophila melanogaster), chick (Gallus gallus) and zebrafish (Danio rerio), as detailed elsewhere4. Rather than providing a comprehensive overview of the entire field of early development, this short timeline DEVELOPMENTAL CELL BIOLOGY — TIMELINE presents a personal account of the status of experimental embryology, a field that a Spemann’s organizer and self- century ago was at the very front of biologi- cal research. regulation in amphibian embryos Gene-fishing in Spemann’s organizer The starting point for understanding self- Edward M. De Robertis regulation was provided by the most famous experiment in embryology, the Spemann– Abstract | In 1924, Spemann and Mangold demonstrated the induction of Siamese Mangold organizer (hereafter referred to as twins in transplantation experiments with salamander eggs. Recent work in Spemann’s organizer) graft with salamander amphibian embryos has followed their lead and uncovered that cells in signalling eggs5 (BOX 1). This experiment established centres that are located at the dorsal and ventral poles of the gastrula embryo the present view that animal development communicate with each other through a network of secreted growth-factor results from a succession of cell–cell induc- antagonists, a protease that degrades them, a protease inhibitor and bone- tions in which groups of cells, or organizing centres, signal the differentiation of their morphogenic-protein signals. neighbours. The dorsal-lip graft induced neighbouring cells to adopt the normal pat- When an embryo is cut in half, it can blastomeres is gently pipetted out of a frog tern of tissue types, so that a Siamese twin self-regulate to regenerate the missing part embryo (instead of killing it and leaving it was formed. In 1988, a memoir recounting (FIG. 1). The field of experimental embryol- in place), amphibians too could self-regulate the heyday of experimental embryology in ogy originated in 1883 when Roux killed and give rise to a complete embryo from half the Spemann laboratory was published by one of two cells in a frog embryo with a an egg2. Viktor Hamburger6. At least in my case, the hot needle and found that the rest gave rise In 1903, Hans Spemann used a baby-hair modern revival of studies into Spemann’s to only part of the embryo, usually a right loop (from his own daughter) to subdivide organizer can be traced to this little book, or a left half 1 (TIMELINE). However, in 1891, the cleaving amphibian (salamander) egg which retold the excitement of discover- Driesch separated the two first blastomeres into two halves. If the half-embryo con- ing the inductive powers of the organizer. of the sea urchin embryo and found that tained part of the future blastopore dorsal Hamburger was 88 years old at the time each was able to self-regulate and give rise lip (the region where involution of the — clearly, it is never too late to impact the to complete, although smaller, embryos1. In mesoderm starts), it formed a perfectly well- scientific thinking of others. 1895, Thomas Hunt Morgan — who before proportioned tadpole1 (FIG. 1). In 1918, the In our own laboratory, studies on becoming a geneticist was an experimental great American embryologist Ross Harrison Spemann’s organizer were approached by embryologist — repeated Roux’s experi- carried out another remarkable experiment: cloning its molecular components: cDNA ment and showed that if one of the two if the forelimb field in the mesoderm of libraries were generated from manually 296 | APRIL 2006 | VOLUME 7 www.nature.com/reviews/molcellbio PERSPECTIVES in situ hybridizations of Gsc mRNA, consti- tuted a truly memorable event, because Gsc mRNA demarcated, very specifically, tissue belonging to Spemann’s organizer. Since its discovery almost three-quarters of a century earlier, the existence of Spemann’s organizer had been deduced from its inductive effects after transplantation, but the expression pat- tern of Gsc now allowed us to visualize, for the first time, that the Spemann’s organizer existed as a distinct molecular entity8. A few months later, the groups of Igor Dawid and Milan Jamrich reported that genes encoding two other transcription factors, Xlim1 and Xfkh1/Hnf3β, were also expressed in the organizer region of the African clawed frog9,10. Importantly, microinjection of Gsc mRNA into ventral cells caused the formation of twinned axes, which indicated that the Gsc gene was part of the molecular machinery that leads to the Figure 1 | Embryonic self-regulation. The entire early embryo constitutes a self-differentiating activity of Spemann’s organizer8. Because morphogenetic field, in which cells communicate with each other over great distances. This is Gsc encodes a DNA-binding protein, we demonstrated by experiments such as the one shown here, in which an African clawed frog (Xenopus proposed that it might, in turn, activate the laevis) embryo was cut into two halves at the blastula stage. If it is ensured that both halves contain expression of secreted signalling proteins part of the dorsal organizer region, two perfect identical twins are obtained (an intact sibling is shown that execute the cell-differentiation changes at the top of the figure). In humans, identical twins are found in 3 out of 1,000 live births, and arise most frequently by the spontaneous separation of the inner cell mass of the mammalian blastula into two, in neighbouring cells. In time this was, in 11,12 followed by self-regulation60. The ultimate example of self-regulation is provided by another mammal, fact, found to be the case . The Gsc gene the nine-banded armadillo, in which every blastocyst gives rise to four genetically identical siblings50. was subsequently isolated in many other Note that each twin is longer than just half the length of the intact sibling, which represents yet another species, and became a widely used marker effort to regulate towards the normal pattern. Both half-embryos shown here are derived from the for comparative studies of gastrulation13. same blastula. In 1992, Richard Harland reported the isolation of the first secreted protein that was expressed in Spemann’s organizer14.
Load more

Recommended publications
  • Embryonic Regeneration by Relocalization of the Spemann
    Embryonic regeneration by relocalization of the PNAS PLUS Spemann organizer during twinning in Xenopus Yuki Moriyamaa,b,1 and Edward M. De Robertisa,b,2 aHoward Hughes Medical Institute, University of California, Los Angeles, CA 90095; and bDepartment of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-1662 Contributed by Edward M. De Robertis, April 3, 2018 (sent for review February 16, 2018; reviewed by Makoto Asashima, Atsushi Suzuki, and Naoto Ueno) The formation of identical twins from a single egg has fascinated side of the embryo in regularly cleaving embryos (9). The op- developmental biologists for a very long time. Previous work had posite, darker side of the embryo gives rise to the ventral (belly) shown that Xenopus blastulae bisected along the dorsal–ventral side. The displacement of egg cytoplasmic determinants along (D-V) midline (i.e., the sagittal plane) could generate twins but at microtubules toward the dorsal side triggers an early Wnt signal very low frequencies. Here, we have improved this method by (10), which is responsible for localizing the subsequent formation using an eyelash knife and changing saline solutions, reaching of the Spemann organizer signaling center in the marginal zone frequencies of twinning of 50% or more. This allowed mechanistic at the gastrula stage. The Spemann organizer is a tissue that analysis of the twinning process. We unexpectedly observed that secretes a mixture of growth factor antagonists, such as Chordin, the epidermis of the resulting twins was asymmetrically pig- Noggin, Follistatin, Cerberus, Frzb1, and Dickkopf, which are mented at the tailbud stage of regenerating tadpoles.
    [Show full text]
  • Repair of Ultraviolet Irradiation Damage to a Cytoplasmic
    Proc. Nat. Acad. Sci. USA Vol. 72, No. 4, pp. 1235-1239, April 1975 Repair of Ultraviolet Irradiation Damage to a Cytoplasmic Component Required for Neural Induction in the Amphibian Egg (cortex/vegetal hemisphere/gray crescent/dorsal lip/gastrulation) HAE-MOON CHUNG AND GEORGE M. MALACINSKI Department of Zoology, Indiana University, Bloomington, Ind. 47401 Communicated by Robert Briggs, January 2, 1975 ABSTRACT Localized ultraviolet irradiation of the am- In order to gain direct insight into whether an ultraviolet phibian egg destroys a cytoplasmic component that is sensitive component(s) localized in the egg cytoplasm prior required for neural induction. Destruction of that com- ponent severely diminishes the inducing capacity of the to first cleavage division is actually involved in neural dorsal lip at gastrulation, as determined by embryological induction, the following question was posed: Does regional assays. Repair of the ultraviolet lesion can be achieved by UV damage to the egg affect the subsequent inducing capacity replacing the dorsal lip of the irradiated embyro with a of the dorsal lip during gastrulation? By assaying for inducing lip from an unirradiated embryo. capacity of dorsal lips from irradiated embryos and replacing Various types of analyses have established that components the dorsal lips of irradiated embryos with normal lips it was of the amphibian egg cytoplasm influence the pattern of early possible to conclude that UV does indeed damage a localized morphogenesis (see ref. 1 for a review). One of the most component of the egg cytoplasm that is necessary for neural conveniently demonstrated, yet most incompletely under- morphogenesis. stood, cytoplasmic components in the amphibian egg is the MATERlALS AND METHODS gray crescent.
    [Show full text]
  • GTPBP2 Is a Positive Regulator of TGF- Signaling, and Is Required for Embryonic Patterning in Xenopus
    SSStttooonnnyyy BBBrrrooooookkk UUUnnniiivvveeerrrsssiiitttyyy The official electronic file of this thesis or dissertation is maintained by the University Libraries on behalf of The Graduate School at Stony Brook University. ©©© AAAllllll RRRiiiggghhhtttsss RRReeessseeerrrvvveeeddd bbbyyy AAAuuuttthhhooorrr... GTPBP2 is a positive regulator of TGF- signaling, and is required for embryonic patterning in Xenopus. A Dissertation Presented by Arif Kirmizitas to The Graduate School in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Molecular and Cellular Biology Stony Brook University December 2008 Stony Brook University The Graduate School Arif Kirmizitas We, the dissertation committee for the above candidate for the Doctor of Philosophy degree, hereby recommend acceptance of this dissertation. Gerald H. Thomsen – Dissertation Advisor Professor, Department of Biochemistry and Cell Biology Howard I. Sirotkin – Chairperson of Defense Associate Professor, Department of Neurobiology and Behavior Nancy C. Reich Professor, Department of Molecular Genetics and Microbiology A. Wali Karzai Associate Professor, Department of Biochemistry and Cell Biology Bernadette C. Holdener Associate Professor, Department of Biochemistry and Cell Biology Daniel S. Kessler Associate Professor, Department of Cell and Developmental Biology,University of Pennsylvania School of Medicine, Philadelphia, PA This Dissertation is accepted by the Graduate School. Lawrence Martin Dean of the Graduate School ii Abstract of the Dissertation GTPBP2 is a positive regulator of TGF- signaling, and is required for embryonic patterning in Xenopus. by Arif Kirmizitas Doctor of Philosophy in Molecular and Cellular Biology Stony Brook University 2008 The Transforming Growth Factor (TGF-) superfamily of signaling proteins regulate a diverse set of biological processes, including cell proliferation, adhesion, migration, apoptosis, differentiation and embryonic pattern formation.
    [Show full text]
  • The Cleavage Stage Origin of Spemann's Organizer: Analysis Of
    Development 120, 1179-1189 (1994) 1179 Printed in Great Britain © The Company of Biologists Limited 1994 The cleavage stage origin of Spemann’s Organizer: analysis of the movements of blastomere clones before and during gastrulation in Xenopus Daniel V. Bauer1, Sen Huang2 and Sally A. Moody2,* 1Department of Anatomy and Cell Biology, University of Virginia 2Department of Anatomy and Neuroscience Program, The George Washington University Medical Center, 2300 I Street, NW Washington, DC 20037, USA *Author for correspondence SUMMARY Recent investigations into the roles of early regulatory the ventral animal clones extend across the entire dorsal genes, especially those resulting from mesoderm induction animal cap. These changes in the blastomere constituents or first expressed in the gastrula, reveal a need to elucidate of the animal cap during epiboly may contribute to the the developmental history of the cells in which their tran- changing capacity of the cap to respond to inductive growth scripts are expressed. Although fates both of the early blas- factors. Pregastrulation movements of clones also result in tomeres and of regions of the gastrula have been mapped, the B1 clone occupying the vegetal marginal zone to the relationship between the two sets of fate maps is not become the primary progenitor of the dorsal lip of the clear and the clonal origin of the regions of the stage 10 blastopore (Spemann’s Organizer). This report provides embryo are not known. We mapped the positions of each the fundamental descriptions of clone locations during the blastomere clone during several late blastula and early important periods of axis formation, mesoderm induction gastrula stages to show where and when these clones move.
    [Show full text]
  • Competition Between Noggin and Bone Morphogenetic Protein 4
    Proc. Natl. Acad. Sci. USA Vol. 92, pp. 12141-12145, December 1995 Developmental Biology Competition between noggin and bone morphogenetic protein 4 activities may regulate dorsalization during Xenopus development YAEL RE'EM KALMA*, TERESA LAMBt, AND DALE FRANK*t *Department of Biochemistry, The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel; and tDepartment of Molecular and Cellular Biology, Division of Biochemistry and Molecular Biology, 401 Barker Hall, University of California, Berkeley, CA 94720 Communicated by John Gerhart, University of California, Berkeley, CA, September 15, 1995 ABSTRACT Bone morphogenetic protein 4 (BMP-4) in- dorsalization signal (6-9), it is not clear how distinct axial borders duces ventral mesoderm but represses dorsal mesoderm for- are defined within the developing embryo. It is possible that cell mation in Xenopus embryos. We show that BMP-4 inhibits two borders are defined by a combination of positive and negative signaling pathways regulating dorsal mesoderm formation, pathways which demarcate the dorsal/ventral border. the induction of dorsal mesoderm (Spemann organizer) and Bone morphogenetic protein 4 (BMP-4) is a member of the the dorsalization of ventral mesoderm. Ectopic expression of transforming growth factor ( family (11). The gene has been BMP-4 RNA reduces goosecoid and forkhead-l transcription isolated from Xenopus laevis, and ectopic expression of in vitro in whole embryos and in activin-treated animal cap explants. synthesized BMP-4 RNA in developing embryos causes de- Embryos and animal caps overexpressing BMP-4 transcribe velopmental changes which suggest that BMP-4 protein in- high levels of genes expressed in ventral mesoderm (Xbra, duces ventroposterior mesoderm.
    [Show full text]
  • Proquest Dissertations
    REGULATION OF THE BMP SIGNALLING PATHWAY BY BMPl-RELATED METALLOPROTEASES FIONA CLAIRE WARDLE A Thesis Submitted for the Degree of Doctor of Philosophy at the University of London 1998 Department of Anatomy and Developmental Biology University College, London. ProQuest Number: 10016134 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest. ProQuest 10016134 Published by ProQuest LLC(2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. Microform Edition © ProQuest LLC. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 ABSTRACT Bone Morphogenetic Proteins (BMPs) 2-8 are members of the TGFp superfamily of secreted signalling molecules. During embryonic development BMPs are involved in many processes including cell fate determination, morphogenesis, growth and programmed cell death, all of which are essential for normal development. BMP activity may be regulated in variety of ways. Of particular interest is the finding that three Xenopus proteins. Noggin, Chordin and Follistatin are able to bind BMP4 and prevent it activating its receptor (Piccolo et al., 1996; Zimmerman et al., 1996; Fainsod et al., 1997). Inhibition by Chordin can be alleviated by Xolloid, a BMP 1-related metalloprotease that cleaves Chordin (Piccolo et al., 1997). Similarly, in the Drosophila embryo Dpp, a BMP2/4 homologue, is inhibited by the Chordin homologue, Sog, but activated by Tolloid, a BMP 1-related metalloprotease (Marqués et al., 1997).
    [Show full text]
  • On the Nature and Function of Organizers Alfonso Martinez Arias* and Ben Steventon*
    © 2018. Published by The Company of Biologists Ltd | Development (2018) 145, dev159525. doi:10.1242/dev.159525 REVIEW On the nature and function of organizers Alfonso Martinez Arias* and Ben Steventon* ABSTRACT organizer to birds and mammals in experiments in which he Organizers, which comprise groups of cells with the ability to instruct transplanted a piece from the leading edge of the primitive streak of adjacent cells into specific states, represent a key principle in chicken, duck and rabbit embryos into early chicken embryos and developmental biology. The concept was first introduced by observed a duplication of the anteroposterior axis of the host Spemann and Mangold, who showed that there is a cellular (Waddington, 1932, 1954). The tissue he was transplanting population in the newt embryo that elicits the development of a contained a structure known as the node (see Glossary, Box 1), secondary axis from adjacent cells. Similar experiments in chicken and led to a conceptual association between the node and the and rabbit embryos subsequently revealed groups of cells with similar organizer. An important landmark in all these experiments is instructive potential. In birds and mammals, organizer activity is often the emergence of a secondary nervous system at the beginning of the associated with a structure known as the node, which has thus been inductive process, and for this reason the function of the organizer is ‘ ’ considered a functional homologue of Spemann’s organizer. Here, often associated with a process called neural induction (De we take an in-depth look at the structure and function of organizers Robertis and Kuroda, 2004; De Robertis et al., 2000; Stern, 2005).
    [Show full text]
  • Pintallavis, a Gene Expressed in the Organizer and Midline Cells of Frog Embryos: Involvement in the Development of the Neural Axis
    Development 116 81-93 (1992) 81 Printed in Great Britain © The Company of Biologists Limited 1992 Pintallavis, a gene expressed in the organizer and midline cells of frog embryos: involvement in the development of the neural axis A. RUIZ i ALTABA and T. M. JESSELL Howard Hughes Medical Institute, Center for Neurobiology, Department of Biochemistry and Molecular Biophysics,Columbia University,701 W. 168th Street, New York, N. Y. 10032, USA Summary We have identified a novel frog gene, Pintallavis (the chord. Overexpression of Pintallavis perturbs the devel- Catalan for lipstick), that is related to the fly fork head opment of the neural axis, suppressing the differen- and rat HNF-3 genes. Pintallavis is expressed in the tiation of anterior and dorsal neural cell types but caus- organizer region of gastrula embryos as a direct zygotic ing an expansion of the posterior neural tube. Our response to dorsal mesodermal induction. Subsequently, results suggest that Pintallavis functions in the induc- Pintallavis is expressed in axial midline cells of all three tion and patterning of the neural axis. germ layers. In axial mesoderm expression is graded with highest levels posteriorly. Midline neural plate cells that give rise to the floor plate transiently express Pin - Key words: axial mesoderm, midline, neural induction, organizer, tallavis, apparently in response to induction by the noto- Pintallavis, Xenopus laevis. Introduction trulation and extend along the A-P axis giving rise primar- ily to the prechordal plate and notochord. Ectodermal cells The development of the basic body plan of vertebrate adjacent to the dorsal lip, a region known as the dorsal non- embryos depends on inductive interactions and morpho- involuting marginal zone (NIMZ, Keller and Danilchik, genetic movements that take place during gastrulation (Ger- 1988) remain in the ectoderm but also extend along the hart and Keller, 1986; Hamburger, 1988).
    [Show full text]
  • Introducing the Spemann-Mangold Organizer: Experiments and Insights That Generated a Key Concept in Developmental Biology
    Int. J. Dev. Biol. 45: 1-11 (2001) Introducing the Spemann-Mangold organizer 1 Introducing the Spemann-Mangold organizer: experiments and insights that generated a key concept in developmental biology KLAUS SANDER*,1 and PETER E. FAESSLER2 1Institut für Biologie I (Zoologie), Freiburg, Germany and 2Lehrstuhl für Wirtschafts- und Sozialgeschichte der Technischen Universität, Dresden, Germany “What has been achieved is but the first step; we still stand in the presence spent a year in Spemann’s institute and helped him with the English of riddles, but not without hope of solving them. And riddles with the hope version of his book (Spemann 1938). Two witnesses of that period of solution - what more can a man of science desire?” who had seen the film felt that Eakin’s performance gives a good (Hans Spemann, Croonian Lecture 1927) impression of Spemann’s gist for lecturing. Hans Spemann (Fig. 1) gained early fame by his work on lens induction in frogs (Sander 1985, Saha 1991). Evocation of the The “organizer paper” by Hans Spemann and Hilde Mangold “outer parts of the eye” by an outgrowth of the nerve tube (the (1924) initiated a new epoch in developmental biology. It marked optical vesicle) had been postulated early in the 19th century (von the climax of Spemann’s life-long research, and the “organizer Baer 1828; Oppenheimer 1970b), but Spemann’s experiments effect” received special mention by the committee that honoured were the first to raise considerable interest; perhaps not so much him with the Nobel Prize for physiology and medicine in 1935. This by their results than by the long-lasting controversy these trig- introduction precedes a translation of that paper by Spemann’s gered.
    [Show full text]
  • Lect17+18-376F09(Induction).Pdf
    10/23/09 We are walking and standing with parts of our bodies which could have been used for thinking had they developed in another part of the embryo. Hans Spemann, 1943 Reading from Chapter 3 - types of cell specification Chapter 6 - cell-cell signaling (molecules, pathways) Chapter 10 - amphibian axis formation 2nd Hourly Exam - Friday, October 30 Skip ʻAutonomous & conditional cell specification...ʼ lecture currently listed for Oct. 19 for now Autonomous Conditional Syncitial 1 10/23/09 Figure 3.8 Autonomous Specification in the Early Tunicate Embryo Figure 3.15 Drieschʼs Demonstration of Regulative Development Figure 3.12 In the Early Developmental Stages of Many Vertebrates, the Separation of the Embryonic Cells Can Create Twins Future identical quadruplets from a single blastodisc in the nine- banded armadillo 2 10/23/09 Hans Spemann & Ross Harrison 1869-1941 1870-1959 Figure 10.18 Spemannʼs Demonstration of Nuclear Equivalence in Newt Cleavage Figure 7.33 Reorganization of Cytoplasm in the Newly Fertilized Frog Egg 3 10/23/09 Figure 10.19 Asymmetry in the Amphibian Egg Figure 10.20 Determination of Ectoderm During Newt Gastrulation 4 10/23/09 Figure 10.21(1) Organization of a Secondary Axis by Dorsal Blastopore Lip Tissue The Spemann & Mangold Experiment Dark Light donor Host Figure 10.12 Graft of Cells From Dorsal Marginal Zone of a Salamander Embryo Sinks into a Layer of Endodermal Cells and forms a Blastopore-like Groove The Spemann & Mangold Experiment Figure 10.21(2) Organization of a Secondary Axis by Dorsal Blastopore Lip
    [Show full text]
  • Molecular Nature of Spemann's Organizer: the Role of the Xenopus
    Cell, Vol. 67, 111 I-1 120, December 20, 1991, Copyright 0 1991 by Cell Press Molecular Nature of Spemann’s Organizer: the Role of the Xenopus Homeobox Gene goosecoid Ken W. Y. Cho,’ Bruce Biumberg, dorsal cells of the embryo (Gimiich and Gerhart, 1984; Herbert Steinbeisser, and Eddy M. Lh? Robertis Gimlich, 1988) the so-called Nieuwkoop center (Gerhart Molecular Biology institute et al., 1989). Experiments involving coculture of tissue and Department of Biological Chemistry fragments suggest that cells from the Nieuwkoop center University of California release diffusible signals that in turn induce Spemann’s Los Angeles, California 90024-l 737 organizer activity in the overlying marginal zone ceils (Nieuwkoop, 1973). One of the most important recent advances in Xenopus Summary embryology is the discovery that peptide growth factors mediate mesoderm induction. Factors related to basic fi- This study analyzer, the function of the homeobox gene brobiast growth factor (bFGF) can induce ventral meso- goosecold in Xenopus development. First, we find that derm (blood, mesothelium, mesenchyme, and some mus- gooaecoid mFiNA distribution closely mimics the ex- cle), while growth factors of the TGF-8 family, in particular pected localization of organizer tissue in normal em- activin (also called XTC-MIF), are very potent dorsal meso- bryos as well as in those treated with LiCi and UV light. derm inducers (prechordal mesoderm, notochord, and Second, goosecoid mRNA accumulation is induced muscle) (Slack et al., 1989; Smith et al., 1989; Green and by activin, even in the absence of protein synthesis. Smith, 1990). Uncommitted ceils from the animal cap (top) it is not affected by bFGF and is @passed by retinoic region of Xenopus biastulae acquire Spemann’s organizer acid.
    [Show full text]
  • The LIM Domain-Containing Homeo Box Gene Xlim-1 Is Expressed Specifically in the Organizer Region of Xenopus Gastrula Embryos
    Downloaded from genesdev.cshlp.org on September 26, 2021 - Published by Cold Spring Harbor Laboratory Press The LIM domain-containing homeo box gene Xlim-1 is expressed specifically in the organizer region of Xenopus gastrula embryos Masanori Taira/'^ Milan Jamrich,^ Peter J. Good/ and Igor B. Dawid^ ^Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20852 USA; ^Department of Biochemistry, Chiba University School of Medicine, Chiba 280, Japan; ^Laboratory of Molecular Pharmacology, Center for Biologies Evaluation and Research, Food and Drug Administration, Bethesda, MD 20852 USA A novel cysteine-rich motif, named LIM, has been identified in the homeo box genes lin-ll, Isl-1, and mec-S', the mec-3 and lin-ll genes determine cell lineages in Caenorhabditis elegans. We isolated LIM class homeo box genes from Xenopus laevis that are closely related to lin-ll and mec-3 in the LIM and homeo domains. This paper deals with one of these genes, Xlim-1. Xlim-1 mRNA is found at low abundance in the unfertilized egg, has a major expression phase at the gastrula stage, decreases, and rises again during the tadpole stage. In adult tissues the brain shows the highest abundance, by far, of Xlim-1 mRNA. The maternal and late expression phases of the Xlim-1 gene suggest that it has multiple functions at different stages of the Xenopus life cycle. In the gastrula embryo, Xlim-1 mRNA is localized in the dorsal lip and the dorsal mesoderm, that is, in the region of Spemann's organizer.
    [Show full text]