As a result of the molecular genetic analysis of development similar mechanisms for the regulation of gene expression are found in a wide range of organisms. In "Development - the Molecular Genetic Approach" these common mechanisms as well as the specific events leading to a differentiated cell are described. Particular items treated are, for example, how asymmetry is achieved, how cell size is determined, how cell division is controlled, how cell lineage influences development, how cells know their position, and how cells communicate during development.

Section 1 Microbial Systems, Both Prokaryote and Eukaryote.- 1 Virus Assembly and Morphogenesis.- 1.1 Introduction.- 1.1.1 Viruses as Model Systems for Development.- 1.1.2 Self-Assembling Systems: Molecular Ontogeny?.- 1.1.3 General Principles of Virus Organisation.- 1.2 Molecular Mechanisms of Viral Assembly.- 1.2.1 T4 Bacteriophage, a Complex Virus.- 1.2.1.1 Tobacco Mosaic Virus, a Helical Rod.- 1.2.1.2 Tomato Bushy Stunt Virus, an Icosahedral Shell.- 1.2.1.3 Other Examples: Reovirus.- 1.3 Structural Conservation in Icosahedral Viruses.- 1.3.1 A Conserved Protein Domain.- 1.3.2 Evolutionary Considerations.- 1.4 Outlook.- 1.5 Summary.- References.- 2 Bacillus subtilis Sporulation: a Paradigm for the Spatial and Temporal Control of Gene Expression.- 2.1 Introduction.- 2.1.1 B. subtilis: One of the Best-Known of All Organisms.- 2.1.2 The B. subtilis Life Cycle.- 2.1.3 Advantages and Disadvantages of B. subtilis as an Experimental System.- 2.2 The Powerful Molecular Genetic Approach.- 2.2.1 Defining the Developmental Genes.- 2.2.2 Cloning and Physical Characterization of spo Genes.- 2.2.3 Pathways of Gene Expression.- 2.2.4 Transcriptional Control of spo Gene Expression.- 2.3 Stage 0: Proliferation or Development.- 2.3.1 What Factors Influence the Decision to Initiate Sporulation?.- 2.3.2 The Roles of the spo0 Gene Products.- 2.4 Stages II to III: Generation of Cellular Asymmetry.- 2.4.1 Cellular Asymmetry.- 2.4.2 Differential Gene Expression.- 2.5 Stages IV to V: Differential Morphogenesis.- 2.5.1 Synthesis of the Spore Cortex and Coat Layers.- 2.5.2 Temporal Control of Gene Expression.- 2.6 Outlook and Summary.- References.- 3 Development in Caulobacter crescentus.- 3.1 Introduction.- 3.2 Each Cell Division Cycle Produces a Stalked and a Swarmer Cell.- 3.2.1 Stalked Cell and Swarmer Cell Carry Out Different Programs.- 3.2.2 Methods for Obtaining Synchronous Cell Populations.- 3.2.3 DNA Replication Is Under Cell Cycle Control.- 3.2.4 Membrane Growth and Cell Division.- 3.3 The C. crescentus Flagellum Is Similar to other Bacterial Flagelli.- 3.3.1 The Structure of the Flagellum Is Complex.- 3.3.2 Flagellar Gene Organization.- 3.3.3 Flagellar Assembly Proceeds from the Inside to the Outside.- 3.4 Transcription Controls Timing and Level of Flagellar Gene Expression.- 3.4.1 Alternate Promoters and a Variety of Regulatory Factors.- 3.4.2 Regulatory Hierarchy.- 3.4.3 Timing.- 3.5 Gene Products Are Segregated to the Appropriate Daughter Cell.- 3.5.1 Flagellins.- 3.5.2 Chemotaxis Proteins.- 3.5.3 Pilin.- 3.5.4 Heat-Shock Proteins.- 3.6 Mutations and Antibiotics with Pleiotropic Effects Define Dependent Pathways and Common Developmental Steps.- 3.7 Environmental Influences on C. crescentus.- 3.8 Outlook.- 3.9 Summary.- References.- 4 Streptomyces coelicolor: a Mycelial, Spore-Bearing Prokaryote.- 4.1 Introduction.- 4.2 Physiological Aspects of Early Events in Streptomyces Differentiation.- 4.2.1 Is There an Universal First Signal for Differentiation in Streptomyces?.- 4.2.2 Pheromones and Differentiation in Streptomyces spp..- 4.3 Genes Involved in Streptomyces Differentiation - an Overview.- 4.3.1 The Use of Streptomyces coelicolor for Genetic Studies.- 4.3.2 What Genes are Switched On in Response to the Signals for Initiation of Differentiation?.- 4.4 Development and Metamorphosis of the Aerial Mycelium.- 4.4.1 The Emergence of Aerial Hyphae.- 4.4.2 Overview of Sporulation of Aerial Hyphae and Its Genetic Control in S. coelicolor.- 4.4.3 The Crucial Role of a Transcription Factor in the Onset of Sporulation.- 4.4.4 Not All Sporulation Genes Depend on whiG for Expression.- 4.4.5 RNA Polymerase Diversity in S. coelicolor and Its Relevance to Differentiation.- 4.4.6 The Spore Pigment Locus whiE As a Potential Tool in Analysing Spore Development.- 4.4.7 A Role for Sigma-WhiG in Physiological Regulation?.- 4.5 Implications.- 4.6 Outlook.- 4.7 Summary.- References.- 5 The Programme of Cell Type Determination in Fission Yeast.- 5.1 Introduction.- 5.2 Life Cycle.- 5.2.1 Asexual Life Cycle.- 5.2.2 Sexual Life Cycle: Evidence for Three Cell Types.- 5.3 mat 1 Locus and the Cell types.- 5.4 Mating Type Switching: Homothallism Versus Heterothallism.- 5.5 The Programme of Switching.- 5.6 The Mating Type Region.- 5.7 "Position-Effect" Control for Expression and Switching of Cassettes.- 5.8 Trans-acting switch Genes.- 5.9 The Programme of Switching Is Dictated by Parental DNA Chain Inheritance.- 5.10 Comparison of S. pombe with S. cerevisiae Mating Type Interconversion.- 5.11 Outlook.- 5.12 Summary.- References.- 6 Development in Neurospora crassa.- 6.1 Introduction.- 6.2 Life Cycle.- 6.3 Microbiological and Genetic Techniques.- 6.4 Morphological Studies.- 6.4.1 From Spore to Mycelium.- 6.4.2 From Mycelium to Conidia.- 6.4.3 The Sexual Cycle.- 6.5 Influence of the Environment on Development.- 6.5.1 Environmental Factors Identified So Far.- 6.5.2 The Biological Meaning of Environmental Influence on Development.- 6.6 Developmental Genes of Neurospora.- 6.6.1 Biosynthetic and Developmental Pathways Have Little in Common.- 6.6.2 About the Pleiotropism of Developmentally Relevant Genes.- 6.6.3 On the Role of Mitochondria in Development.- 6.7 The Carbohydrate Pathways and Development.- 6.8 Molecular Biology.- 6.8.1 The Mating Type Locus.- 6.8.2 Gene Regulation During Conidiation.- 6.8.3 Blue Light Regulates Many Genes.- 6.9 Outlook.- 6.10 Summary.- References.- 7 Genetic Regulation of Sporulation in the Fungus Aspergillus nidulans.- 7.1 Introduction.- 7.2 Conidiation in the Wild type.- 7.2.1 General Considerations.- 7.2.2 Induction of Conidiation.- 7.2.3 Morphological Alterations.- 7.3 Molecular Genetic Facilities.- 7.3.1 Mutation.- 7.3.2 Complementation.- 7.3.3 Strain Construction and Genetic Mapping.- 7.3.4 DNA-Mediated Transformation.- 7.4 How Many Genes Are Needed for Growth and Development?.- 7.5 Analysis of Development with Stage-Specific Mutants.- 7.5.1 Mutants of Interest.- 7.5.2 Mutants Found but Ignored.- 7.5.3 Mutants Expected but Not Found.- 7.6 Characteristics of Important Developmental Mutants.- 7.6.1 General Considerations.- 7.6.2 Velvet Mutants.- 7.6.3 Fluffy Mutants.- 7.6.4 Aconidial Mutants.- 7.6.5 Bristle Mutants.- 7.6.6 Abacus Mutants.- 7.6.7 Stunted Mutants.- 7.6.8 Medusa Mutants.- 7.6.9 Ivory (Conidiophore Pigment) Mutants.- 7.6.10 Rodletless Mutants.- 7.6.11 Benomyl-Resistant Mutants.- 7.6.12 Wet-White Mutants.- 7.6.13 Spore Color Mutants.- 7.7 Molecular Analysis of Developmental Regulation.- 7.7.1 General Considerations.- 7.7.2 Isolation and Characterization of Regulatory Genes.- 7.7.3 Isolation and Characterization of Responder Genes.- 7.7.4 Controlled Induction of Regulatory Genes.- 7.8 Comparisons with Other Systems.- 7.9 Outlook.- 7.10 Summary.- References.- 8 Development of Trypanosomes.- 8.1 Introduction.- 8.1.1 Why Study Parasites?.- 8.1.2 Trypanosoma and Leishmania Species.- 8.1.3 The Life Cycle of Trypanosoma brucei.- 8.2 Trypanosomes as an Experimental System.- 8.2.1 Trypanosoma and Leishmania - in Vitro and in Vivo Cultivation Are Practical in the Laboratory.- 8.2.2 Energy Metabolism and Respiration in Trypanosoma and Leishmania Species.- 8.2.3 The Nuclei of Trypanosoma and Leishmania Species Have Unusual Properties.- 8.2.4 Trypanosomes Have a Special Mechanism of RNA Processing..- 8.2.5 The Expression of VSG Proteins Is Vital to the Bloodstream Form…