Dictyostelium Discoideum: A Developmental System presents D. discoideum as a model eukaryotic system to study a variety of developmental problems. The book describes the life cycle of the organism D. discoideum which exists in nature as a soil amoeba in forest detritus. The nuclei of D. discoideum contain DNA, RNA, and proteins which have properties similar to those of histones present in calf thymus nuclei. The unique sequences of the genome of the organism code for the gene products synthesize during its growth and development. One approach in genetic analyses to understanding the developmental processes of the organism is to isolate a large number of morphological mutants. The isolation process will indicate the number of variations that are open to the developing system, and will point to causal connections between stages. The text also explains that the number of cells which differentiate into stalk cells is the result of timing and mechanics of the process of culmination. Ashworth (1971) suggests that cells in pseudoplasmodia of D. discoideum adjust their positions in relation to the chemical structure of the sheath itself. A model shows how cells communicate their response to the sheath in an axial fashion. The book can prove beneficial for biochemists, micro-biologists, cellular researchers, and investigators involved in the study of cellular biology.

Contenu

Preface
Chapter 1 The Life Cycle
An Overview
Related Species
Chapter 2 Amoeboid Stage
Growth Conditions
Amoeboid Movement in D. Discoideum
Feeding
Ultrastructure
Chapter 3 The Genome
Karyotype
Nuclear Composition
Mitochondrial DNA
Repetitive Sequences
Unique Sequences
Chapter 4 Genetics of Dictyostelium
Genetic Approaches
Mutational Genetics
Parasexuality
Sexuality
Stock Maintenance
Chapter 5 Aggregation Stage
Chemotaxis
Periodic Movement
Cohesion of Developing Cells
Chapter 6 Pseudoplasmodial Stage
Integration
Polarity of Migration
Phototaxis
Thermotaxis
Cell Sorting in Pseudoplasmodia
Chapter 7 Culmination Stage
Stalk Formation
Spore Formation
Avoidance Reaction
Germination Inhibitor
Germination
Mutational Analysis of Culmination
Chapter 8 Macromolecular Aspects of Development
Decrease in Dry Weight and Oxygen Consumption
Protein Content
RNA Content
Polysaccharide Content
DNA Content
Axenically Grown Cells
RNA Metabolism
Structure of Nuclear and Cytoplasmic RNA
Transcriptional Changes
Chapter 9 Enzymatic Aspects of Development
Enzymes of the Growth Phase
Enzymes of Growth and Development
Enzymes of Development
Marker Enzymes of Development
Enzyme Synthesis
Enzyme Degradation
Stage-Specific Enzymes
Mutational Analysis of Stage-Specific Enzymes
Chapter 10 Changes in Metabolites during Development
Cells Grown on Bacteria
Axenically Grown Cells
Chapter 11 The Relation of Biochemical Differentiations to Morphogenesis
Aggregation
Pseudoplasmodium Formation
Culmination
Glycogen Metabolism
Substrate Concentrations
Metabolic Modeling
Genetic Analysis
Chapter 12 Modifications of Development
Submerged Cultures
Cell Density
Overhead Light
Dissociation
Mechanical Barriers
Effect of Nutrients
Phenocopies of Aggregateless Mutants
Phenocopies of Fruitless Mutants
Phenocopies of Culmination Mutants
Growth Conditions
Genetic Modifications
Synergy
Chapter 13 Tissue Proportioning
Size Invariance
Mechanical Analysis
Differentiations of Prespore and Prestalk Cells
Cell Sorting and Determination
Regulation of Tissue Proportions
Positional Information
Cell Contact Model
Diffusional Barrier Model
Structural Model
Bibliography
Subject Index