DOCSLIB.ORG

Dynamics of the Control of Body Pattern in the Development of Xenopus Laevis 1

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dynamics of the Control of Body Pattern in the Development of Xenopus Laevis 1 J. Embryol. exp. Morph. 88, 85-112 (1985) 85 Printed in Great Britain © The Company of Biologists Limited 1985 Dynamics of the control of body pattern in the development of Xenopus laevis 1. Timing and pattern in the development of dorsoanterior and posterior blastomere pairs, isolated at the 4-cell stage JONATHAN COOKE AND JOHN A. WEBBER National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7, U.K SUMMARY Xenopus embryos have been selected in which the second cleavage is occuring in a frontal plane, i.e one tending to lie at right angles to the prospective plane of bilateral symmetry for the body pattern. Some of these have been used to deduce a map of the disposition of materials for the normal mesodermal pattern (the normal 'fate map') by injecting blastomeres to found fluorescently marked clones from 4- to 32-cell stages. Other such 4-cell embryos have been separated into two isolates across this second cleavage; in fate-map terms, prospective dorsoanterior and posterior isolates. These have been allowed to develop to control axial larval stages, with examination of the time schedule of their gastrulation movements in relation to cofertilized whole controls. The patterns of mesoderm produced have been examined and interpreted in the light of quantitative knowledge about the normal pattern, and our current understanding of the map. A meaningful fate map exists for the egg material even at this early, essentially acellular stage, and it differs appreciably from what might have been expected in view of that traditionally shown for early gastrula stages. The patterns developed in the isolates show that at least in many eggs, widespread information that positively specifies material as to its body position is available from at most 1 h after the events that give rise to bilateral symmetry upon fertilization. This information usually leads to a mosaic development of the appropriate mesodermal part-pattern in dorsoanterior isolates, and frequently allows development that approximates to this in the reciprocal posterior part. Regulation, i.e. the replacement of removed information to specify a development more complete than the normal contribution in isolates, is not observed. The results suggest a revision of former claims for regulative ability in at least this amphibian embryo. They also imply that systems for ascribing position value (positional information) to early embryonic tissue can be diverse in dynamics, even among embryos whose body plans are obviously homologous as are those of vertebrates. INTRODUCTION This is the first of a series of papers which will report a re-appraisal of pattern formation in the development of an anuran amphibian, using the contemporary techniques of cell lineage marking and the quantitative measurement of anatomy at a particular early larval stage. These techniques have been used alongside various traditional experimental manipulations, performed on newly fertilized Key words: egg organization, pattern specification, gastrulation, fate mapping, non-equivalence, Xenopus laevis. 86 J. COOKE AND J. A. WEBBER eggs and early embryos of the African Clawed Frog, Xenopus laevis. An overall attempt to introduce these studies in terms of the inherited beliefs and concepts of experimental embryology would result, rather, in a lengthy review. The reader is referred instead to reviews by Holtfreter & Hamburger (1955), Nieuwkoop (1973) and Gerhart (1980, especially relevant for the events before first cleavage). In each of the present papers, revisions of particular previously held beliefs that are indicated by results to be described will be emphasized in the appropriate discussion sections. Attempts will be made at appropriate points to inter-relate the findings as a whole. This and the next paper deal with the traditional separation of the fertilized egg into defined fragments at very early cleavage stages, and their development in isolation. The results are partly at variance with the traditional reports, and resemble those recently documented by Kageura & Yamana (1983). They may help in understanding the nature of the information that underlies development of the body plan in embryos of this general type (Wolpert, 1971; Cooke, 1983a, b). Spemann and his students, working with urodele embryos, recorded that a special limited region of the egg could be defined, at least from soon after fertilization (Spemann, 1902, 1938). Constrictions were made, at times up to the onset of gastrulation, to produce developing fragments each reasonably balanced for constituents in the animal-vegetal axis. Any such fragment that included the region destined to become the dorsal midline in the normal course of embryo- genesis, could apparently develop an essentially complete, balanced body pattern though of reduced tissue dimensions (i.e regulation). Fragments lacking this region revealed, by their retention of radial symmetry and lack of dorsal axial histogenesis, a profound loss of developmental information. The crucial 'pre-localized' region was originally believed to be quite limited, subtending some 60° of arc in the egg, but later experiments of similar sorts revealed that the situation was more complex (Brice, 1958; Dollander, 1950; Fankhauser, 1948) and that a wider region was capable of organizing at least a significant partial degree of development. The extent to which the experimental patterns were analysed histologically and quantitatively, to see if they accorded with their 'gestalt' appearance, is also unclear. This work has nevertheless been the classic evidence for the idea that prolonged interactions or signalling processes across tissue, extending through blastula and into gastrula phases (104 cells), set up the body pattern by progressive regionalization during the normal development. This development has in its turn been treated as a model system in which to study early pattern formation in vertebrates generally. The mechanism has been thought of sometimes as a hierarchy or succession of specific inductions (Spemann, 1938; Nieuwkoop, 1973; Slack, 1983; see Cooke, 1983a) and sometimes as the setting up of a physiological gradient interpreted as positional information of some kind (Cooke, 1912a, 1973; Wolpert, 1971). We have re-investigated the states of specification for patterned development across the egg by capitalizing upon the recently expanded knowledge of the immediate postfertilization events in anuran amphibians, particularly Xenopus Pattern in Xenopus blastomere pairs 87 (Gerhart et al. 1981; Kirschner, Gerhart, Hara & Ubbels, 1980). By appropriate early manipulation and selection of eggs, preparations can be made in which the two pairs of blastomeres separated at the 4-cell stage will constitute, respectively, that part of the egg surrounding the presumptive dorsal midline and the remainder. It is known that the system organizing the future pattern is first orientated during the precleavage period by reorganization of plasms within the egg. This normally occurs in relation to the position of sperm entry which can be used as a marker. At second cleavage (orientated vertically like the first but orthogonal to it), we have selected eggs with a bilaterally symmetrical cleavage pattern lying orthogonal to the presumptive plane of symmetry of the embryo. Some were then used to fill particular bilateral pairs of blastomeres with a cell- lineage tracer (Gimlich & Cooke, 1983), and thus trace their relative contributions to mesodermal body pattern in normal development. Those contributions turn out to be quite characteristic and constant, so that a fate-mapping exercise has been performed, and the deduced map for mesoderm differs from what might be expected in view of previously published fate maps for amphibian early gastrula stages. The remaining eggs were used to perform separations into the two presumed bilaterally symmetrical pairs of blastomeres, followed by their devel- opment as isolates. The partial body plans developed by these reciprocal isolates were observed and representative samples examined histologically. Their meso- dermal component was studied in relation to our understanding of the fate map for whole development, and our knowledge of certain quantitative regularities in the normal pattern (Webber & Cooke, in preparation). We conclude that, by onset of the 4-cell stage, the informational system across the egg is frequently in such a condition as to lead to stable retention, by the separated parts, of the ability to develop in a near-mosaic way their reciprocal contributions to the normal whole mesoderm. Regulative behaviour - that is, production by a fragment of a greater part of the pattern than its presumptive contribution in the intact embryo - was not observed. Mosaic behaviour is not the invariable outcome however, and the whole spectrum of results is discussed in terms of the possible nature of the primary system of spatial information in the egg. Our understanding of the flow of developmental information that sets up and co-ordinates the principal layers of the body structure (germ layers) is also discussed in relation to the present results, in order to justify our concentration upon mesoderm as the most direct expression of the original system coding for 'body position'. We stress that the results reveal an early specification for position within the body plan (see Slack, 1983 for a defined usage of this term), and in no sense a set of determinations for tissue types. The behaviour which is described indeed precedes by several hours the origin of
Load more

Recommended publications
  • Neuromesodermal Progenitors Are a Conserved Source of Spinal
    © 2019. Published by The Company of Biologists Ltd | Development (2019) 146, dev175620. doi:10.1242/dev.175620 CORRECTION Correction: Neuromesodermal progenitors are a conserved source of spinal cord with divergent growth dynamics (doi: 10.1242/dev.166728) Andrea Attardi, Timothy Fulton, Maria Florescu, Gopi Shah, Leila Muresan, Martin O. Lenz, Courtney Lancaster, Jan Huisken, Alexander van Oudenaarden and Benjamin Steventon Light-sheet imaging data associated with Development (2018) 145, dev166728 (doi: 10.1242/dev.166728) are now available in the Image Data Repository with an explanatory Data Note hosted by Wellcome Open Research. The corrected Data availability section is shown below and both the online full-text and PDF versions have been updated. Data availability (corrected) Sequencing data associated with the ScarTrace lineage tracing study have been deposited in GEO under accession number GSE121114. The Matlab script allowing for user-defined selection of tracking data can be found here: doi.org/10.5281/zenodo.1475146. Light-sheet imaging data associated with Fig. 7 have been deposited in the Image Data Repository (https://idr.openmicroscopy.org/webclient/?show=project-552) with an associated Data Note hosted by Wellcome Open Research (https:// wellcomeopenresearch.org/articles/3-163/v1). Data availability (original) Sequencing data associated with the ScarTrace lineage tracing study have been deposited in GEO under accession number GSE121114. The Matlab script allowing for user-defined selection of tracking data can be found here: doi.org/10.5281/zenodo.1475146. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
    [Show full text]
  • The Genetic Basis of Mammalian Neurulation
    REVIEWS THE GENETIC BASIS OF MAMMALIAN NEURULATION Andrew J. Copp*, Nicholas D. E. Greene* and Jennifer N. Murdoch‡ More than 80 mutant mouse genes disrupt neurulation and allow an in-depth analysis of the underlying developmental mechanisms. Although many of the genetic mutants have been studied in only rudimentary detail, several molecular pathways can already be identified as crucial for normal neurulation. These include the planar cell-polarity pathway, which is required for the initiation of neural tube closure, and the sonic hedgehog signalling pathway that regulates neural plate bending. Mutant mice also offer an opportunity to unravel the mechanisms by which folic acid prevents neural tube defects, and to develop new therapies for folate-resistant defects. 6 ECTODERM Neurulation is a fundamental event of embryogenesis distinct locations in the brain and spinal cord .By The outer of the three that culminates in the formation of the neural tube, contrast, the mechanisms that underlie the forma- embryonic (germ) layers that which is the precursor of the brain and spinal cord. A tion, elevation and fusion of the neural folds have gives rise to the entire central region of specialized dorsal ECTODERM, the neural plate, remained elusive. nervous system, plus other organs and embryonic develops bilateral neural folds at its junction with sur- An opportunity has now arisen for an incisive analy- structures. face (non-neural) ectoderm. These folds elevate, come sis of neurulation mechanisms using the growing battery into contact (appose) in the midline and fuse to create of genetically targeted and other mutant mouse strains NEURAL CREST the neural tube, which, thereafter, becomes covered by in which NTDs form part of the mutant phenotype7.At A migratory cell population that future epidermal ectoderm.
    [Show full text]
  • Floral Ontogeny and Histogenesis in Leguminosae. Kittie Sue Derstine Louisiana State University and Agricultural & Mechanical College
    Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1988 Floral Ontogeny and Histogenesis in Leguminosae. Kittie Sue Derstine Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Derstine, Kittie Sue, "Floral Ontogeny and Histogenesis in Leguminosae." (1988). LSU Historical Dissertations and Theses. 4493. https://digitalcommons.lsu.edu/gradschool_disstheses/4493 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. INFORMATION TO USERS The most advanced technology has been used to photo­ graph and reproduce this manuscript from the microfilm master. UMI films the original text directly from the copy submitted. Thus, some dissertation copies are in typewriter face, while others may be from a computer printer. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyrighted material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are re­ produced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. Each oversize page is available as one exposure on a standard 35 mm slide or as a 17" x 23" black and white photographic print for an additional charge. Photographs included in the original manuscript have been reproduced xerographically in this copy.
    [Show full text]
  • THE HISTOGENESIS of BONE by C
    THE HISTOGENESIS OF BONE By C. WITHERINGTON STUMP, M.D. From the Laboratory of the Royal College of Physicians, Edinburgh INTRODUCTION FEW processes in histogenesis have been the subject of so much controversy, as that of the development of bone. On reading over the literature, even incompletely, the conviction came with considerable force, that the chief cause of the inability of observers, to find agreement, lay in technical difficulties in obtaining satisfactory preparations for cytological study. The divergent opinions are accounted for by the singular absence of detailed work-a fact which has fostered and sustained a controversy into which there is no need to enter. Microscopic evidence of cell growth and change is yielded by slight morpho- logical variations in different individual cells. Slight differences in structure, and staining reaction, are the only factors by means of which variations can be determined. It is essential, with cells examined in a dead state, to have a standard of fixation which registers detailed and minute structure. Further, it is constantly to be borne in mind, that merely a phase of life is represented, through which the cell was passing at the time of its death. Especially is this so in actively growing, developing tissue, where many structural tendencies are manifested by the act of growth. Thus, in fixed primitive tissue, the ontogeny of any given cell is a matter of conjecture, and it can only be defined with any degree of certainty by an experienced observer. It would be redundant to attempt an historical survey of the contributions to the problem of osteogenesis.
    [Show full text]
  • Histogenesis of Ovarian Malignant Mixed Mesodermal Tumours J Clin Pathol: First Published As 10.1136/Jcp.43.4.287 on 1 April 1990
    J Clin Pathol 1990;43:287-290 287 Histogenesis of ovarian malignant mixed mesodermal tumours J Clin Pathol: first published as 10.1136/jcp.43.4.287 on 1 April 1990. Downloaded from T J Clarke Abstract embedded tumour tissue were cut at 4 im and The histogenesis of ovarian malignant stained with haematoxylin and eosin, periodic mixed mesodermal tumours, which acid Schiff (PAS) before and after diastase includes the concept of metaplastic car- treatment, Caldwell and Rannie's reticulin cinoma, is controversial. Four such stain, and phosphotungstic acid haematoxylin tumours were examined for evidence of (PTAH). Sequential sections were stained by metaplastic transition from carcinoma to the indirect immunoperoxidase technique sarcoma using morphology and reticulin using monoclonal antibodies directed against stains. Consecutive sections were stained cytokeratin (PKK1 which reacts with low immunohistochemically using cyto- molecular weight cytokeratins of44, 46, 52 and keratin and vimentin to determine 54 kilodaltons), vimentin, a-l-antitrypsin and whether cells at the interface between myoglobin. Appropriate positive and negative carcinoma and sarcoma expressed both controls, with omission of specific antisera in cytokeratin and vimentin. There was no the latter, were performed. Haematoxylin and evidence ofmorphological, architectural, eosin stained sections were examined for or immunohistochemical transitions secondary fluorescence using a Leitz Dialux from carcinoma to sarcoma in the four 20ES microscope and mercury vapour light tumours studied. This suggests that source epifluorescence. ovarian malignant mixed mesodermal Four patients, aged 68, 71, 72 and 73 presen- tumours are not metaplastic carcinomas ted with abdominal distension and discomfort but are composed of histogenetically dif- and were found to have an ovarian malignant ferent elements.
    [Show full text]
  • Development and Control of Tissue Separation at Gastrulation in Xenopus
    Developmental Biology 224, 428–439 (2000) doi:10.1006/dbio.2000.9794, available online at http://www.idealibrary.com on View metadata, citation and similar papers at core.ac.uk brought to you by CORE Development and Control of Tissue Separation provided by Elsevier - Publisher Connector at Gastrulation in Xenopus Stephan Wacker,* Kristina Grimm,* Thomas Joos,†,1 and Rudolf Winklbauer*,†,2 *Universita¨t zu Ko¨ln, Zoologisches Institut, Weyertal 119, 50931 Ko¨ln, Germany; and †Max-Planck-Institut fu¨r Entwicklungsbiologie, Abt. Zellbiologie/V, Spemannstrasse 35, 72076 Tu¨bingen, Germany During Xenopus gastrulation, the internalizing mesendodermal cell mass is brought into contact with the multilayered blastocoel roof. The two tissues do not fuse, but remain separated by the cleft of Brachet. This maintenance of a stable interface is a precondition for the movement of the two tissues past each other. We show that separation behavior, i.e., the property of internalized cells to remain on the surface of the blastocoel roof substratum, spreads before and during gastrulation from the vegetal endoderm into the anterior and eventually the posterior mesoderm, roughly in parallel to internalization movement. Correspondingly, the blastocoel roof develops differential repulsion behavior, i.e., the ability to specifically repell cells showing separation behavior. From the effects of overexpressing wild-type or dominant negative XB/U or EP/C cadherins we conclude that separation behavior may require modulation of cadherin function. Further, we show that the paired-class homeodomain transcription factors Mix.1 and gsc are involved in the control of separation behavior in the anterior mesoderm. We present evidence that in this function, Mix.1 and gsc may cooperate to repress transcription.
    [Show full text]
  • Ectoderm Induces Muscle-Specific Gene Expression in Drosophila
    Development 121, 1387-1398 (1995) 1387 Printed in Great Britain © The Company of Biologists Limited 1995 Ectoderm induces muscle-specific gene expression in Drosophila embryos Rob Baker1,* and Gerold Schubiger2 1Department of Genetics and 2Department of Zoology, University of Washington, Seattle, WA 98195, USA *Author for correspondence at present address: Department of Anatomy, University of Wisconsin, 1300 University Avenue, Madison WI 53706, USA SUMMARY We have inhibited normal cell-cell interactions between mesoderm cells to express nautilus (a MyoD homologue) mesoderm and ectoderm in wild-type Drosophila embryos, and to differentiate somatic myofibers, whereas dorsal and have assayed the consequences on muscle development. ectoderm induces mesoderm cells to express visceral and Although most cells in gastrulation-arrested embryos do cardiac muscle-specific genes. Our findings suggest that not differentiate, they express latent germ layer-specific muscle determination in Drosophila is regulated by genes appropriate for their position. Mesoderm cells induction between germ layers during gastrulation. require proximity to ectoderm to express several muscle- specific genes. We show that ventral ectoderm induces Key words: Drosophila, induction, myogenesis, cell signalling INTRODUCTION larval muscles, it is not known when muscle determination occurs. One possibility is that differential nuclear uptake of the Induction in amphibian embryos has been originally described dorsal morphogen within the presumptive mesoderm deter- by Spemann and Mangold (1924), and has since been studied mines different myogenic fates, just as it specifies the fate of in many species. In vertebrate embryos, cell-cell interactions the presumptive ectoderm, mesectoderm, and mesoderm between the mesoderm and ectoderm are required for the (Kosman et al., 1991; Ray et al., 1991; St.
    [Show full text]
  • Melanotic Neuroectodermal Tumor of Infancy (MNTI) and Pineal Anlage Tumor (PAT) Harbor a Medulloblastoma Signature by DNA Methylation Profiling
    cancers Article Melanotic Neuroectodermal Tumor of Infancy (MNTI) and Pineal Anlage Tumor (PAT) Harbor A Medulloblastoma Signature by DNA Methylation Profiling Oscar Lopez-Nunez 1,† , Rita Alaggio 2,*,†, Ivy John 3 , Andrea Ciolfi 4, Lucia Pedace 5, Angela Mastronuzzi 5 , Francesca Gianno 6 , Felice Giangaspero 6,7 , Sabrina Rossi 2 , Vittoria Donofrio 8, Giuseppe Cinalli 8 , Lea F. Surrey 9 , Marco Tartaglia 4, Franco Locatelli 5,10 and Evelina Miele 5,* 1 Division of Pathology and Laboratory Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA; [email protected] 2 Pathology Unit, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; [email protected] 3 Department of Pathology and Laboratory Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA; [email protected] 4 Genetics and Rare Diseases Research Division, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; andrea.ciolfi@opbg.net (A.C.); [email protected] (M.T.) 5 Department of Pediatric Onco-Hematology and Cell and Gene Therapy, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy; [email protected] (L.P.); [email protected] (A.M.); [email protected] (F.L.) 6 Radiologic, Oncologic and Anatomo-Pathological Sciences Department, Sapienza University, 00161 Rome, Italy; [email protected] (F.G.); [email protected] (F.G.) 7 IRCCS Neuromed, Pozzilli, 86077 Isernia, Italy 8 Pathology Unit, Azienda Ospedaliera Santobono-Pausilipon, 80122 Naples, Italy; Citation: Lopez-Nunez, O.; Alaggio, [email protected] (V.D.); [email protected] (G.C.) R.; John, I.; Ciolfi, A.; Pedace, L.; 9 Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Mastronuzzi, A.; Gianno, F.; Pennsylvania, Philadelphia, PA 19104, USA; [email protected] Giangaspero, F.; Rossi, S.; Donofrio, 10 Department of Pediatrics, Sapienza University of Rome, 00161 Rome, Italy V.; et al.
    [Show full text]
  • Resegmentation Is an Ancestral Feature of the Gnathostome Vertebral Skeleton Katharine E Criswell1,2*, J Andrew Gillis1,2
    RESEARCH ARTICLE Resegmentation is an ancestral feature of the gnathostome vertebral skeleton Katharine E Criswell1,2*, J Andrew Gillis1,2 1Department of Zoology, University of Cambridge, Cambridge, United Kingdom; 2Marine Biological Laboratory, Woods Hole, United States Abstract The vertebral skeleton is a defining feature of vertebrate animals. However, the mode of vertebral segmentation varies considerably between major lineages. In tetrapods, adjacent somite halves recombine to form a single vertebra through the process of ‘resegmentation’. In teleost fishes, there is considerable mixing between cells of the anterior and posterior somite halves, without clear resegmentation. To determine whether resegmentation is a tetrapod novelty, or an ancestral feature of jawed vertebrates, we tested the relationship between somites and vertebrae in a cartilaginous fish, the skate (Leucoraja erinacea). Using cell lineage tracing, we show that skate trunk vertebrae arise through tetrapod-like resegmentation, with anterior and posterior halves of each vertebra deriving from adjacent somites. We further show that tail vertebrae also arise through resegmentation, though with a duplication of the number of vertebrae per body segment. These findings resolve axial resegmentation as an ancestral feature of the jawed vertebrate body plan. Introduction Axial segmentation is key to the body plan organization of many metazoan groups and has arisen repeatedly throughout animal evolution (Davis and Patel, 1999). Within vertebrates, the axial skele- ton is segmented into repeating vertebral units that provide structural support and protection for *For correspondence: soft tissues. Vertebral segmentation is preceded in the embryo by the segmentation of paraxial [email protected] mesoderm into epithelial blocks called somites (Figure 1a).
    [Show full text]
  • Evo Devo.Pdf
    FROM EMBRYOLOGY TO EVO-DEVO Dibner Institute Studies in the History of Science and Technology George Smith, general editor Jed Z. Buchwald and I. Bernard Cohen, editors, Isaac Newton’s Natural Philosophy Jed Z. Buchwald and Andrew Warwick, editors, Histories of the Electron: The Birth of Microphysics Geoffrey Cantor and Sally Shuttleworth, editors, Science Serialized: Representations of the Sciences in Nineteenth-Century Periodicals Michael Friedman and Alfred Nordmann, editors, The Kantian Legacy in Nineteenth-Century Science Anthony Grafton and Nancy Siraisi, editors, Natural Particulars: Nature and the Disciplines in Renaissance Europe J. P. Hogendijk and A. I. Sabra, editors, The Enterprise of Science in Islam: New Perspectives Frederic L. Holmes and Trevor H. Levere, editors, Instruments and Experimentation in the History of Chemistry Agatha C. Hughes and Thomas P. Hughes, editors, Systems, Experts, and Computers: The Systems Approach in Management and Engineering, World War II and After Manfred D. Laubichler and Jane Maienschein, editors, From Embryology to Evo-Devo: A History of Developmental Evolution Brett D. Steele and Tamera Dorland, editors, The Heirs of Archimedes: Science and the Art of War Through the Age of Enlightenment N. L. Swerdlow, editor, Ancient Astronomy and Celestial Divination FROM EMBRYOLOGY TO EVO-DEVO: A HISTORY OF DEVELOPMENTAL EVOLUTION edited by Manfred D. Laubichler and Jane Maienschein The MIT Press Cambridge, Massachusetts London, England © 2007 Massachusetts Institute of Technology All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means (including photocopying, recording, or information storage and retrieval) without permission in writing from the publisher.
    [Show full text]
  • PDX-1 Is Required for Posterior Poregut Patterning and Differentiation of the Pancreas and Duodenum
    PDX-l IS REQUIRED FOR POSTERIOR FOREGUT PATTERNING AND D~~TIONOFTHEPANCREASANDDUODENUM By MARTIN F. OFFIELD Dissertation Submitted to the Faculty of the Graduate School of V anderbilt University for the degree of DOCTOR OF PHaOSOPHY in Cell Biology December, 1996 Nashville, Tennessee r L To Donna and my parents who always believed in me lV ACKNOWLEDGEMENTS The financial support for the research of this dissertation was provided by the National Institutes of Health (grant #HD28062 to C.V.E.W. and #DK42502 to C.V.E.W. and Mark Magnuson) and by the Howard Hughes Medical Institute (funding to Brigid L. M. Hogan). The research described in this dissertation was done in collaboration with the labs of Mark Magnuson and Brigid Hogan. Specifically, the electroporation of pdx-l targeting constructs and subsequent production of chimeric animals was carried out by Patricia (Trish) Labosky of Brigid Hogan's lab. It was Trish's expertise in this area that allowed us to move very quickly with these experiments. Linda Hargett was also involved in this process and helped in the breeding and maintenance of the mouse lines. Tom Jetton of Mark Magnuson's lab was responsible for much of the immunostaining necessary for the analysis of the pdx-l mutants. Tom was not only the supplier of many of the antibodies used in these analyses, but he has been an encyclopedic source of information on pancreatic gene expression and function. Tom has been more than helpful in our attempts to analyze and describe the defects seen in pdx­ I null animals. Mike Ray of Chris Wright's lab aided in the cloning of pdx -1 and also in the genotyping many of the animals drived from the pdx -1 mutant lines.
    [Show full text]
  • Observations of Dependent Histogenesis in Salamander Limb Development
    /. Embryol. exp. Morph., Vol. 11, Part 2, pp. 325-338, June 1963 Printed in Great Britain Observations of Dependent Histogenesis in Salamander Limb Development by CYRIL V. FINNEGAN1 From the Department of Zoology, University of British Columbia INTRODUCTION PREVIOUS work in this laboratory (Finnegan, 1962) had suggested that limb development might be specifically enhanced by experimentally associated somite mesoderm tissue. Detwiler (1938), Swett (1945) and Nicholas (1958) called atten- tion to the influence of this mesoderm in the production of duplications when limb buds were transplanted heterotopically to the superficial somite region and, more recently, Amano (1960) stated that somite tissue was required, inductively and materially, for limb development. In an analysis of development it is assumed that a group of cells, whose histo- genesis has been determined by their previous experience, will evidence that histo- genesis if placed in an environment in which they continue to develop. Thus, after limb bud transplantation to the flank in urodeles, positive results (that is, histo- genesis, proximally, accompanied by growth, distally) have been interpreted as self-differentiation of the limb bud cell mass (see review by Nicholas, 1955). However, the possible synergistic role of the somite mesoderm in the histogenesis of the transplant has not been considered. It may be that greater histogenetic competence has been ascribed to the limb cell mass than it actually posesses. In this respect Wilde (1950) was able to show, by in vitro studies, a dependency of limb differentiation on donor developmental age. The more ventral region of the urodele flank has been considered an unfavour- able site for limb development (Nicholas, 1924; Takaya, 1938) since limb bud transplanted to that region does not continue its development.
    [Show full text]