Actinopterygians

Posterior Hox genes expressed In both appendages VERTEBRATES paired appendages a p poiarily of tin structure posterior Hox genes expressed In both appendages VERTEBRATES paired appendages a p poiarily of tin structure cluster activity must have been involved at this step i.e., at (c) in Fig. 5.4C. Since forelimb and hindlimb buds develop into structurally homologous appendages, and both express sets of posterior box genes, this expression denotes a discrete patterning cassette. The forelimb...

Regulation of Direct Cell Type Specification in Early Development

The Basic Package for Bilaterian Embryogenesis Type 1 Specification Processes 64 Regulatory Mechanism in Territorial Specification of the The Definitive Territories of the Embryo 66 Early Transcriptional Activation of Cell Type-specific Genes 71 Initial Regulatory Processes 74 Multiple Inputs for Endomesoderm Specification 75 Regulatory Mechanisms Controlling Specification in Mechanisms and Pathways in Mesoderm Specification 85 Caenorhabditis Elegans The Genomic Apparatus for Endoderm...

Drosophila And Distal-less

Drosophila And Distal Less

FIGURE 4.5 Rhombomere specification in hindbrain establishment of essential spatial regulatory states. (A) Correlation of domains of spatial expression of indicated genes in the amniote hindbrain with respect to specific rhombomeres From this diagram alone one can see that each rhombomere expresses a unique combination of developmentally important genes. The remainder of Fig. 4.5 concerns the functional significance of the two genes shown at the top of Fig. 4.5A, i.e., krox20and kreisler. The...

Genome size kb

FIGURE I.I Complexity of egg RNA plotted against genome size for different species. Data are from RNA excess hybridization against single-copy DNA or cDNA hybridization kinetics, and are expressed in terms of length of single-copy DNA sequence represented in the egg RNA. Echinoderms are shown in red 2, Arbacia 4, Strongylocentrotus 6, Lytechinus 7, Tripneustes (all sea urchins) I0, Pisaster (a starfish). Dipteran insects are in black I, Drosophila 3, Musca (the housefly). Amphibians are in blue...

References

A., and McGhee, J. D. (1991). Spatial control of gut-specific gene expression during Caenorhabditis elegans development. Science 252,579-252. Abzhanov, A., and Kaufman, T. C. (1999). Homeotic genes and the arthropod head Expression patterns of labial, proboscipedia, and Deformed genes in crustaceans and insects. Proc. Natl. Acad. Sci. USA 96, 10224-10229, 267. Abzhanov, A., and Kaufman, T. C. (2000). Crustacean (malacostracan) Hoxgenes and the evolution of the arthropod...

Rrh

FIGURE 4.10 Early development of trachea in Drosophila. (A) Expression of trachealess (trh) gene, which encodes a bHLH-PAS transcription factor, and acts as a determinant of tracheal identity. The locus contains a 3-gal expression enhancer trap ( -eve-1) and expression of the trh gene is conveniently monitored by use of an a(3-gal antibody. (AI) trh(l-eve-l) expression in ten tracheal placodes normal pattern, stage 11. (A2) trh autoregulates expression is extended anteriorly to generate an...

Operating Principles For Regulatory Systems That Mediate Developmental Specification Events

Specification processes are those by which initially pluripotent embryonic cells choose among diverse fates, and are allocated to a given spatial territory or anlage. To understand the role of cz's-regulatory elements in specification it is necessary to think of them as devices that make choices they produce alternative outputs depending on the sets of inputs with which they are confronted in different cells. As discussed in Chapter 1, in each cell the cz's-regulatory inputs consist of the...

Lhf

Maternal -catenin nuclearization TCF LEF1 System veg2 Endomesoderm Specification Genes Signal dependant -catenin nuclearization FIGURE 3.3 Conditional and autonomous specification of veg2 endomes-odermal domain in the sea urchin embryo. (A) Expression of the endol6 gene is conditional on signaling from micromeres in the 4th-6th cleavage interval. endol6 activity is visualized by in situ hybridization in 24 h S. purpuratus blastulae, following microsurgical removal of all four micromeres at (AI)...

Preface

For about 40 years I have been engaged in the effort to perceive how development is encoded in the DNA, and thereby how animal evolution happened. These are the questions that lie at the heart of functional genomics, at least for those whose fascination is the academic one of learning how life works. But of course in the early days when I entered the field we didn't use terms such as functional genomics, perhaps because the idea of genomics divorced from function had not yet been invented. I...

Chapter

Regulatory Hardwiring A Brief Overview of the Genomic Control Apparatus and its Causal Role in Development and Evolution The Regulatory Apparatus Encoded in the DNA 2 The Genes and Gene Regulatory Components of Animal Overview of Regulatory Architecture 7 Gene Regulatory Functions in Development 11 The Regulatory Demands of Development 11 Terminal Differentiation 16 Genomic Regulatory Sequence and the Evolution of Regulatory Evolution, and Evolution in General 19 Some problems direct the...

Specification of the sea urchin embryo

Sea Urchin Embryo Animal Plate

The Definitive Territories of the Embryo The zygotic mechanisms that lead to the formation of the sea urchin embryo can be defined as a set of territorial specification processes, followed by the downstream events of differentiation. By late cleavage each territory is a unique domain of gene expression, and the cells of each are the unique progenitors of a specific structure of the embryo. The territories constitute a spatially simple map, as shown in Fig. 3.1A-D. Except for some...