Molecular Aspects of Early Development PDF
Preview Molecular Aspects of Early Development
MOLECULAR ASPECTSOF EARLY DEVELOPMENT MOLECULAR ASPECTSOF EARLYDEVELOPMENT Edited by George M. Malacinski and William H. Klein lndiana University Bloomington, lndiana PLENUM PRESS • NEWYORK AND LONDON Library of Congress Cataloging in Publication Data Symposium on Molecular Aspects of Early Development (1982: Louisville, Ky.) Molecular aspects of early development. "Proceedings of the Symposium on Molecular Aspects of Early Devel opment, which was part of the annual meeting of the American Society of Zoologists, held December 29-30, 1982, ... Louisville Ky" -Verso l.p. Includes bibliographical references and indexes. 1. Developmental biology-Congresses. 2. Developmental genetics Congresses. 3. Molecular biology-Congresses. 1. Malacinski, George M. II. Kiein, William H. III. American Society of Zoologists. IV. Title. QH491.S95 1982 591.3 83-19259 ISBN-13: 978-1-4684-4630-2 e-ISBN-13: 978-1-4684-4628-9 DOI: 10.1007/978-1-4684-4628-9 Proceedings of the Symposium on Molecular Aspects of Early Development, which was part of the annual meeting of the American Society of Zoologists, held December 29-30, 1982, at Galt House, Louisville, Kentucky © 1984 Plenum Press, New York Softcover reprint of the hardcover 1s t edition 1984 A Division of Plenum Publishing Corporation 233 Spring Street, New York, N.Y. 10013 All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher PREFACE The early embryo has emerged as the focal point for analysis of the regulation of gene expression for several reasons. First, the fact that embryogenesis is under genetic control has been appreciated from the earliest days of classical embryology. When experimental techniques became available it was therefore logical that they should be applied to the embryo. With each new advance in methodology, interest in embryonic gene expression studies has increased. Second, many embryos offer unique opportunities for the investigation of specific aspects of the regulation of gene expression. Several phenomena--eg., control of translation--can be very conveniently studied in a variety of marine invertebrate embryos. Those embryos contain large stores of maternally inherited mRNA which are translated in a highly ordered fashion during specific stages of post fertilization development. Marine invertebrate eggs can be conveniently artifically inseminated and labeled with radioactive precursors. Their analysis is leading to important insights into the mechanisms which regulate gene expression at post-transcriptional levels. Third, recent advances in both transmission and recombinant DNA genetics, especially in organisms such as Drosophila, are providing special opportunities for the analysis of regulatory mechanisms which operate at the level of the genome. Specific genes have been identified, isolated, and--in some instances--sequenced. The opportunity is now available to study the regulation of the expression of single genes in a vertical fashion--from the primary sequence of the gene to the tissues and organs which are the products of morphogenesis. Fourth, studies on the regulation of gene expression in vertebrate embryos promise to provide fundamental information concerning the basis of congenital defects. Consequently, various amphibian and mammalian embryos have been defined as model systems for investigating molecular aspects of early pattern specification. v vi PREFACE Most embryos employ two gene expression strategies in their early development: the utilization of maternally inherited components, including structural proteins, enzymes, ribosomal, transfer, and messenger RNA; and the de novo synthesis (directed by the zygote's genome) of novel proteinS-and nucleic acids. A common goal of contemporary molecular embryologists is to understand the manner in which maternal vs. zygote contributions regulate early pattern specification. Most investigations begin with descriptive studies which try to determine the extents to which various gene expression patterns change during early embryogenesis. Those studies are then usually follwed by analyses of the relative contributions of the maternal and zygotic genomes. Finally, attempts at identifying and isolating specific genes usually ensue. The reports included in this volume represent research progress towards that common goal. They were presented at a symposium entitled "Molecular Aspects of Early Development" as part of the annual meeting of the American Society of Zoologists (Louisville, Kentucky, December 27-30, 1982). The reports describe how the embryos from various organisms (nematodes, marine invertebrates, insects, amphibia, and mammals) are currently being exploited with modern techniques (protein fractionation, recombinant DNA probes monoclonal antibodies, in situ hybridization, etc.) to formulate coherent views of the manner in which gene expression is regulated in the early embryo. Symposium Organizers George M. Malacinski and William H. Klein CONTENTS The Yellow Crescent of Ascidian Eggs: Molecular Organization, Localization and Role in Early Development . . . . . . . 1 W.R. Jeffery, C.R. TomIinson, R.D. Brodeur and S. Meier Expression of Maternal and Embroyonic Genes During Sea Urchin Development • . 39 B.P. Brandhorst, F. Tufaro and P.-A. Bedard Translational Regulation of Gene Expression in Early Development . . • . . • 61 J.V. Ruderman, E.T. RosenthaI and T. Tansey mRNA Distributions in Sea Urchin Embryos 87 R.C. Angerer, K.J. Hughes, D.V. DeLeon, D.A. Lynn and L.M. Angerer Subcellular Localization of Maternal Histone mRNAs and The Control of Histone Synthesis in The Sea Urchin Embryo ••..••• • . • • 109 R.M. Showman, D.E. Wells, J.A. Anstrom, D.A. Hursh, D.S. Leaf and R.A. Raff A Family of mRNAs Expressed in The Dorsal Ectoderm of Sea Urchin Embryos . . . • • • • . • • . 131 W.H. Klein, L.M. Spain, A.L. Tyner, J. Anstrom, R.M. Showman, C.D. Carpenter, E.D. Eldon and A.M. Bruskin Segregation of Germ-Line-Specific Antigens During Embryogenesis in Caenorhabditis EIegans • • • • . 141 S. Strome and W.B. Wood Genetic and Developmental Approaches to Understanding Determination in Early Development •...••••... 167 K.D. Konrad and A.P. Mahowald vii viii CONTENTS Homoeotic Genes and The'Specification of Segmental Identity in The Embryo and Adult Thorax of Drosophila Me1anogaster • • • • • • • • • 189 T.C. Kaufman and M.K. Abbott Isolation and Characterization of Genes Differentia11y Expressed in Ear1y Drosophila Embryogenesis • • .• .•••.•••••. 219 J.A. Lengye1, S.R. Thomas, P.D. Boyer, F. Sa1as, T.R. Strecker, I. Lee, M.L. Graham, M. Roark and E.M. Underwood Accumu1ation and Behavior of mRNA During Oogenesis and Ear1y Embryogenesis of Xenopus Laevis . • • • • . • . 253 L.E. Hyman, H.V. Co1ot and M. Rosbas Protein Synthesis Patterns During Ear1y Amphibian Embryogenesis . •• ..•.....••.. 267 D.C. Meu1er and G.M. Ma1acinski Changes in Synthesis of RNA and Protein During Reactivation of De1ayed Imp1anting Mouse B1astocysts • • • • • • • • • • • . • • • • • • • • 289 H.M. Weitlauf CONTRIBUTORS 309 PHOTOS OF PARTICIPANTS 313 INDEX .•..•.••. 315 THE YELLOW CRESCENT OF ASCIDIAN EGGS: MOLECULAR ORGANIZATION, LOCALIZATION AND ROLE IN EARLY DEVELOPMENT William R. Jeffery, Craig R. TomIinson, Richard D. Brodeur, and Stephen Meier* ABSTRACT The molecular composition, localization, and role in early development of the yellow crescent cytoplasm is reviewed. The yellow, myoplasmic crescent is a localized cytoplasmic region preferentially distributed to the muscle and mesenchyme lineage cells during early development of ascidian eggs. It consists of a collection of lipid pigment granules with numerous adherent mitochondria underlain by a specific cytoskeletal domain. The yellow crescent cy.toskeleton is comprised of a superficial, sub-membrane network of actin filaments (PML) and a more internal filamentous lattice which connects pigment granules and possibly other cytoplasmic organelles to the cell surface. The yellow crescent originates during oogenesis and is uniformly distributed around the periphery of the mature, unfertilized egg. After fertilization the peripheral cytoplasm streams into the vegetal hemisphere forming the yellow crescent. The yellow crescent cytoskeleton, under the direction of local changes in the concentration of calcium ions, seems to be involved in this movement. Although relatively poor in total mRNA, the yellow crescent is highly enriched in mRNA sequences coding for cytoplasmic actin. The enrichment in actin mRNA is due to an association of these molecules with yellow crescent cytoskeletal elements. In general, however, prevalent messages in the yellow crescent region are not qualitatively different from those in other areas of the egg. A wide variety of different proteins are also found in the yellow crescent which are a subset of those present in *From the Department of Zoology, University of Texas, Austin, TX 78712. 2 W. R. JEFFERY ET AL. the whole egg. There is strong evidence that the yellow crescent contains cytoplasmic determinants which are segregated during cleavage and specify muscle cell properties in the cells they enter. The molecular nature and mode of action of these agents, however, remains to be determined. INTRODUCTION Classical experiments conducted in the early part of the century established an important role for specialized regions of the egg cytoplasm in the control of embryonic determination (for reviews see Wilson, 1925; Davidson, 1976). It has been hypothesized that such regions contain morphogenetic determinants, substances segregated to different cell lineages that are responsible for mediating the developmental choices made by totipotent nuclear genomes (Morgan, 1934). Although these determinative agents remain to be isolated and characterized, there is evidence that some of them may be maternal RNA sequences (Kalthoff, 1979; see Jeffery, 1983b, for review) or pro teins (Brothers, 1979). The absence of visible markers in the specialized cytoplasmic regions of eggs has contributed to the difficu1ty of assessing their developmental significance. There are exceptions to this generalization, however, and some of these have provided our richest sources of information on the role of cytoplasmic factors in early embryogenesis. The oosome, a specialized cytoplasmic region involved in germ cell determination (Illmensee and Mahowald, 1974), is positioned at the posterior pole of dipteran eggs. The oosome contains a unique localization of organelles known as polar granules (see Mahowald et al., 1979, for review). Organelles of similar structure are found in specialized regions of the cytoplasm thought to be involved in germ cell determination in a number of different kinds of eggs (see Jeffery, 1983b, for review). Cytoplasmic regions of specific morphogenetic fate can also be marked by distinct colors in certain eggs, most notably those of ctenophores (Spek, 1926) and ascidians (reviewed by Berrill, 1968). The greatest variety of different colored cytoplasmic regions was discovered in the egg of the ascidian Styela by Conklin (1905a). One of these regions, the yellow crescent, is the subject of this review. We begin by considering the structure and developmental his tory of this specialized cytoplasmic region which is a marker for the larval muscle and mesenchyme cell lineages in ascidian eggs. Next, we review classical and more recent studies on the role of the yellow crescent in muscle cell determination and the nature of the determinative agents. Finally, we outline recent studies on the macromolecular organization and mechanism of localization of the yellow crescent region during early development.
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