Gene Activity in Early Development

Preface


1 Introduction: The Variable Gene Activity Theory of Cell Differentiation

Early Evidence for the Informational Equivalence of Differentiated Cell Genomes

Transdifferentiation

DNA Constancy and Nuclear Transplantation

DNA Sequence Complements of Differentiated Cells Appear Identical

Gene Amplification Cannot Explain Differentiation

Direct Evidence for the Variable Gene Activity Theory of Cell Differentiation

Only Minor Fractions of DNA Sequence Are Transcribed in Any Given Differentiated Cell Type

Diverse Sets of Sequences Are Transcribed in Each Differentiated Cell Type

Differentiated Cell Nuclei Contain Inactive (Nontranscribed) DNA

Cytological Manifestations of Variable Genomic Activity

Measurements of Specific Messenger RNA Accumulation

Transcription Level Gene Regulation in Animal Cells

Levels of Control

DNA Sequence Organization and Transcription Level Regulation


2 The Onset of Genome Control in Embryogenesis

The First Species Hybrid Experiments and Their Conceptual Background

Nineteenth Century Species Hybrid Experiments

Origins of the Chromosome Theory of Cellular Inheritance

Evidence for Delayed Onset of Embryo Genome Control from Echinoderm Species Hybrid Studies

Morphogenesis in Echinoderm Species Hybrids

Biosynthetic Processes in Echinoderm Species Hybrids

Embryo Genome Control in the Development of Species Hybrids in Chordates

Amphibian Hybrids

Teleost and Ascidian Hybrids

Interpretation of the Species Hybrid Experiments

Development in Physically Enucleated Embryos

"Chemical Enucleation": Development of Actinomycin-Treated Embryos

Actinomycin Effects on Echinoderm Embryos

Actinomycin Effects on Chordate Embryos

Effects of Actinomycin and Other Treatments on Early Morphogenesis

Delayed Morphogenetic Response to Experimental Treatments

Interpretation of Morphogenetic Effects


3 First Indices of Differential Embryo Cell Function

Qualitative Changes in Patterns of Protein Synthesis Correlated with Developmental Stage

Changes in Protein Synthesis Pattern Studied by High Resolution Gel Electrophoresis

The Double Label Method

Are Changes in Protein Synthesis Pattern in Early Embryos Post-transcriptional?

First Morphological Indications of Differential Cell Function

Intercellular Junctions in Early Embryos

Other Early Cytodifferentiations

Appearance of Histospecific Proteins

Appearance of Histospecific Proteins before Organogenesis

Differentiation of Primary Mesenchyme Cells in the Sea Urchin

Conclusions


4 Quantitative Aspects of Protein Synthesis in Early Embryos: The Role of Maternal Components

Absolute Rates of Protein Synthesis

Free Amino Acid Pools in Sea Urchin Embryos

Absolute Rates of Protein Synthesis in Sea Urchin Embryos

Absolute Rates of Protein Synthesis in Amphibian Embryos

Maternal Ribosomal and Transfer RNA’s

Translational Capacities of Mature Oocytes and Early Cleavage Stage Embryos

In Vitro Protein Synthesis on Embryo Ribosomes

Injection of Exogenous Messenger RNA into Oocytes

Direct Demonstration of Maternal Messenger RNA

Protein Synthesis in Enucleated Egg Cytoplasm

Isolation and Quantitation of Maternal Messenger RNA

Postribosomal Particles Containing Maternal Messenger RNA

Fertilization and the Utilization of Maternal Message in Sea Urchin Embryos

Increase in Polysomes following Fertilization

Mechanisms of Maternal Messenger RNA Mobilization

Changes in Protein Synthesis Rate during Early Development in Other Organisms

Variations in the Effect of Fertilization on Protein Synthesis Rate

Relative Protein Synthesis Rates in Mammalian Embryos and in Hydrated Artemia Embryos

Synthesis and Inheritance of Some Specific Embryonic Proteins

Nucleosomes and the Requirement for Histones during Early Development

Histone Gene Clusters in the Sea Urchin

Quantitative Aspects of Histone Synthesis during Sea Urchin Embryogenesis

Qualitative Alterations in Histone Synthesis during Early Development

Quantitative Aspects of Histone Synthesis in Xenopus

DNA Polymerases

RNA Polymerases

Microtubule Proteins


5 Transcription in Early Embryos

RNA Synthesis in Amphibian Embryos

Accumulation of Labeled RNA Species

RNA Synthesis and Turnover Kinetics for the Case of Constant Precursor Specific Activity

Synthesis Rates and Steady State Quantities of the Heterogeneous RNAs of Xenopus Embryos

Apparent Change in the Relative Rate of Nuclear RNA Synthesis at Blastula Stage

Ribosomal RNA Synthesis in Xenopus Embryos

Mitochondrial RNA Synthesis in Xenopus Embryos

Transcriptional Rates and Patterns in Sea Urchin Embryos

The Heterogeneous Nuclear RNA of Sea Urchin Embryos

Synthesis and Decay Kinetics of Heterogeneous Nuclear RNA in Sea Urchin Embryos

Synthesis and Decay Kinetics for a Case of Changing Precursor Specific Activity: Calculation of Messenger RNA Synthesis Rates

Classes of Messenger RNA in Sea Urchin Embryos

Mitochondrial RNA Synthesis in Sea Urchin Embryos

Synthesis of Ribosomal and Transfer RNA in Sea Urchin Embryos

Transcription in Mammalian Embryos

Ribosomal RNA Synthesis in Early Mammalian Embryos

Synthesis of Heterogeneous RNAs in Mammalian Embryos

Transfer RNA Synthesis and Messenger RNA Synthesis in Mammalian Embryos

RNA Synthesis in the Embryos of Other Species

Ribosomal RNA Synthesis in Various Embryos

Generalization and a Paradox Regarding Classes of Newly Synthesized Embryonic RNA


6 RNA Sequence Complexity and Structural Gene Transcription in Early Embryos

Sequence Complexity and the Quantitative Analysis of Renaturation Experiments

Definition of Sequence Complexity

Basic Relations between Renaturation Rate Constant and Sequence Complexity

Renaturation of Repetitive Sequences

Kinetics of Disappearance of Single Strand Nucleotides and RNA Hybridization in DNA Excess

RNA Excess Hybridization Kinetics

Sequence Complexity of Oocyte RNA

Single Copy Sequence Complexity of Oocyte RNA’s

Complexity of Repetitive Sequence Transcripts in Oocyte RNA

Oocyte Repetitive Sequence Transcripts in Early Embryos

Repetitive and Nonrepetitive Sequence Transcripts in the Newly Synthesized RNAs of Early Embryos

Absence of Detectable Interspersed Repetitive Sequence Transcripts in Messenger RNA

Interspersed Repetitive Sequence Transcripts in Embryo Nuclear RNA

The Complexity of Embryo Nuclear RNA and Developmental Changes in the Pattern of Nuclear RNA Transcription

Complexity of Mammalian Embryo RNA

Complexity of Repetitive Sequences Transcribed during Embryogenesis

Competition Hybridization Experiments with Embryo RNA’s

The Complexity of Polysomal Messenger RNA in Early Embryos

Complexity of Polysomal Messenger RNA in Sea Urchin Gastrulae

Prevalent and Complex Classes of Embryo Messenger RNA

Changes in Structural Gene Sets Active at Various Stages of Sea Urchin Development


7 Localization of Morphogenetic Determinants in Egg Cytoplasm

Classical Definition of the Localization Phenomenon

Embryo Cell Lineage

Morphogenetic Potentialities of Isolated Blastomeres and Sets of Blastomeres

Localization in the Eggs of Ctenophores

Localization of Determinants for Comb Plate Cilia

Localization of Determinants for Photocyte Differentiation

Cytoplasmic Localization in the Eggs of Ilyanassa and Certain Other Molluscs

Classic Experiments on the Morphogenetic Significance of Polar Lobe Cytoplasm

Morphogenetic Determinants in the Polar Lobe Cytoplasm of Ilyanassa Eggs

Cytological Observations on Polar Lobes

Effects of Polar Lobe Removal on Macromolecular Biosynthesis

Does the Polar Lobe Contain a Specific Set of Maternal Messenger RNA's?

Localization of Germ Cell Determinants

Classic Experiments on Localization of Germ Cell Determinants

Evidence for Germ Cell Determinants in Amphibian Eggs

Polar Granules in Amphibian Eggs

Evidence for Germ Cell Determinants in Drosophila Eggs

Polar Granules in Drosophila Eggs

A Phylogenetic Survey: How Universal Is Cytoplasmic Localization?

Failure to Demonstrate Precise Cytoplasmic Localizations in Eggs of a Turbellarian Flatworm

Localization in Cephalopod Molluscs

Localization in Dipteran Insects

Cytoplasmic Localization in Sea Urchin Eggs

Localization of Capacity to Form Histospecific Enzymes in Ascidian Embryos

Localization of Axial Determinants in Amphibian Egg Cytoplasm

Absence of Evidence for Cytoplasmic Localization in Mammalian Eggs

Phylogenetic Summary

Interpretations of the Localization Phenomenon

Classic Theories of Cytoplasmic Localization in Eggs

"Regulative" and "Mosaic" Eggs

Gradual Establishment of Localization Patterns

Lability of Cytoplasmic Localization Patterns

Tentative Conclusions and Speculations


8 Lampbrush Chromosomes and the Synthesis of Heterogeneous Nuclear and Messenger RNA's during Oogenesis

Structure and Transcription in the Lampbrush Chromosomes of Amphibian Oocytes

DNA Content and Structure of Lampbrush Chromosomes

Specificity of Lampbrush Chromosome Loops

DNA Content of Lampbrush Chromosome Loops

Transcription Units in Lampbrush Chromosomes

Estimates of Complexity and Synthesis Rate for Lampbrush Chromosome RNA from Structural Evidence

The Occurrence of Lampbrush Chromosomes

Stages of Oogenesis and Duration of the Lampbrush Phase in Amphibians

Phylogenese Occurrence of Lampbrush Chromosomes and General Conclusions

Meroistic Oogenesis in Insects and the Role of Germ-Line Gene Expression

Accessory Cell Functions in Meroistic Oogenesis

Structure and Origin of Nurse Cell-Oocyte Complexes in Holometabolous Insects

Synthesis of Oocyte RNA in Nurse Cells

Chromosomal Elements Containing DNA Used Only for Gametogenesis

Analogies between Oocyte Lampbrush Chromosome Loops and Lampbrush Loops in Drosophila Spermatocytes

Synthesis of Ribosomal and Transfer RNAs in the Oocyte Nucleus

Low Molecular Weight Stable RNA’s

Amplification of Genes for 18 S and 28 S Ribosomal RNA’s

Synthesis Rates for Ribosomal RNA in Amphibian Oocytes

Lampbrush Chromosomes and the Synthesis of Heterogeneous Nuclear RNA and Messenger RNA during Oogenesis

Character of Lampbrush Chromosome RNA

Heterogeneous Nuclear RNAs Synthesized in Mature Oocyte Nuclei

Complexity of Oocyte Nuclear RNA’s

Heterogeneous Repetitive Sequence Transcripts Accumulated in Lampbrush Stage Oocytes

Synthesis and Accumulation of Messenger RNA's during Oogenesis

Examples of Structural Gene Products Translated during Oogenesis and Required in Embryogenesis

Is the Main Function of Lampbrush Chromosomes the Synthesis of Maternal Messenger RNA Precursors?

Bibliography

Index