Gene Regulatory Factors That Control The Identities Of Specific Neuron Types In Caenorhabditis Elegans

I have also studied the fate determination of several distinct neuronal cell types. I dissected the cis-regulatory information of AIA expressed genes and identified that the LIM homeodomain transcription factor TTX-3 is required for AIA fate, possibly together with another yet unknown transcription factor. TTX-3 also acts synergistically with the POU-domain transcription factor UNC-86 as master regulators for NSM. TTX-3 may also act as the terminal selector for ASK. This work provides extra evidence for the terminal selector concept and further demonstrates that individual neurons use unique and combinatorial codes of transcription factors to achieve their terminal identities, and that the same regulatory factor can be reused as a terminal selector in distinct cell types through cooperation with different cofactors.

The interaction between biology and evolution has been the subject of great interest in recent years. Because evolution is such a highly debated topic, a biologically oriented discussion will appeal not only to scientists and biologists but also to the interested lay person. This topic will always be a subject of controversy and therefore any breaking information regarding it is of great interest.The author is a recognized expert in the field of developmental biology and has been instrumental in elucidating the relationship between biology and evolution. The study of evolution is of interest to many different kinds of people and Genomic Regulatory Systems: In Development and Evolution is written at a level that is very easy to read and understand even for the nonscientist. * Contents Include* Regulatory Hardwiring: A Brief Overview of the Genomic Control Apparatus and Its Causal Role in Development and Evolution * Inside the Cis-Regulatory Module: Control Logic and How the Regulatory Environment Is Transduced into Spatial Patterns of Gene Expression* Regulation of Direct Cell-Type Specification in Early Development* The Secret of the Bilaterians: Abstract Regulatory Design in Building Adult Body Parts* Changes That Make New Forms: Gene Regulatory Systems and the Evolution of Body Plans

Nervous systems of all organisms are remarkably complex. This complexity is a reflection of the great diversity of the nervous systems' basic units, the neurons. There is a large variety of different neuron types that differ in their morphology, function and their underlying molecular composition. Even though neurons are very diverse, they all share common features, namely cellular projections (axons and dendrites) and synapses. Genes expressed in the entire nervous system, called pan-neuronal genes, encode the molecular correlates to these common features. Although a lot is known about how specific transcription factors, Terminal Selectors (TS), specify the different neuronal types by co-regulating neuron type specific gene expression, much less is understood about the regulatory programs that control the expression of pan-neuronal genes. Addressing this question is key to understanding how neuronal fate is determined. In this thesis I have explored the regulatory logic of pan-neuronal genes in C. elegans.

The human brain is the most complex structure in the known universe and one of the ultimate goals of humanity is to understand its function. The "bottom-up" approach to developmental neuroscience seeks to assemble a "parts list" of the genes expressed in each neuron and a map of the gene regulatory networks that determine the identity of the diverse neuronal types. A key part of building such a gene regulatory map is to identify the transcription factors that are key nodes in these networks. The goal of my PhD was to study the particular gene regulatory networks that govern the decision of the V5 skin cell to divide, lose its skin fate and decide to make dopamine and glutamate sensory neurons. We chose an unbiased forward genetic screen approach coupled with whole genome sequencing of mutants derived from these screens. In the process, we found several mutants that govern this process and developed a software pipeline that simplifies the analysis of mutants for others who perform forward genetic screens.

Derived from the acclaimed online “WormAtlas,†C. elegansAtlas is a large-format, full-color atlas of the hermaphroditic form of the model organism C. elegans, known affectionately as “the worm†by workers in the field. Prepared by the editors of the WormAtlas Consortium, David H. Hall and Zeynep F. Altun, this book combines explanatory text with copious, labeled, color illustrations and electron micrographs of the major body systems of C. elegans. Also included are electron microscopy cross sections of the worm. This laboratory reference is essential for the working worm biologist, at the bench and at the microscope, and provides a superb companion to the C. elegansII monograph. It is also a valuable tool for investigators in the fields of developmental biology, neurobiology, reproductive biology, gene expression, and molecular biology.

This new volume of Current Topics in Developmental Biology covers developmental timing, with contributions from an international board of authors. The chapters provide a comprehensive set of reviews covering such topics as the timing of developmental programs in Drosophila, temporal patterning of neural progenitors, and environmental modulation of developmental timing.

Abstract: Sequence-specific transcription factors are crucial to generating the gene expression patterns that drive the specification, morphogenesis, and physiology of organs and tissues. In order to better understand how organ form and function are orchestrated by transcription factors, we must better understand the genetic inputs and outputs of these critical regulators. In this work, I have utilized C. elegans to characterize the genetic networks and organ functions of three post-embryonically functioning transcription factors. The Pax family of transcription factors is highly conserved across animal species, and controls the development of multiple tissues and organs during development. In C. elegans males, two sensory mating structures, the copulatory spicules and the post-cloacal sensilla, are formed from stereotyped divisions of the two post-embryonic blast cells, B.a and Y.p, respectively. A C. elegans pax-6 transcript, vab-3, is necessary for the development of these sensory structures. Using a green fluorescent protein (GFP)-based vab-3 transcriptional reporter, I found that expression is restricted to the sensory organ lineages of B.a and Y.p. Transcription of vab-3 in the tail region of the worm requires the Abdominal-B homeobox gene, egl-5. Opposing this activation, a transcription factor cascade and a Wnt signaling pathway each act to restrict vab-3 expression to the appropriate cell lineages. Another C. elegans Pax gene, egl-38, is required for the development of the egg-laying system and rectum. However, few EGL-38 target genes are known. Using gene expression microarrays, we cross-referenced microarray data from an inducible EGL-38 strain and two egl-38 mutants that disrupt protein function in a tissue-preferential manner to identify potential tissue-specific EGL-38 target genes. One set of genes from this analysis was validated using GFP reporter transgenes. Most of these genes are expressed in egl-38-dependent tissues, and many display egl-38 dependence. In addition to the identification of target genes, this work revealed enrichments in gene classes that play a role in innate immunity. Consistent with this, we discovered a novel immune function for egl-38. We found that the gene activities of egl-38 and three egl-38-responsive genes from our validation set are associated with increased infection by the pathogenic bacterium M. nematophilum. However, we also show that egl-38 does not impact infection by a different pathogen, S. marcescens. While Pax genes regulate spatial tissue/organ identity, some transcription factors regulate temporal identity. In C. elegans, heterochronic genes function to ensure the precise timing of stage-specific developmental events. I positionally cloned a novel missense allele of the heterochronic transcription factor LIN-14, and revealed a previously undiscovered ability of this protein to solely affect late larval development. lin-14(sa485) hermaphrodites exhibit asynchrony between vulval and gonadal morphogenesis and maturation. Further, lin-14(sa485) preferentially disrupts the timing of vulval cell morphogenesis, but not cell division. I also show that terminal differentiation of a uterine cell type is delayed in lin-14(sa485) mutants.

The first of its kind, this laboratory handbook emphasizes diverse methods and technologies needed to investigate C. elegans, both as an integrated organism and as a model system for research inquiries in cell, developmental, and molecular biology, as well as in genetics and pharmacology. Four primary sections--Genetic and Culture Methods, Neurobiology, Cell and Molecular Biology, and Genomics and Informatics--reflect the cross-disciplinary nature of C. elegans research. Because C. elegans is a simple and malleable organism with a small genome and few cell types, it provides an elegant demonstr.

1 Kevin Moses It is now 25 years since the study of the development of the compound eye in Drosophila really began with a classic paper (Ready et al. 1976). In 1864, August Weismann published a monograph on the development of Diptera and included some beautiful drawings of the developing imaginal discs (Weismann 1864). One of these is the first description of the third instar eye disc in which Weismann drew a vertical line separating a posterior domain that included a regular pattern of clustered cells from an anterior domain without such a pattern. Weismann suggested that these clusters were the precursors of the adult ommatidia and that the line marks the anterior edge of the eye. In his first suggestion he was absolutely correct - in his second he was wrong. The vertical line shown was not the anterior edge of the eye, but the anterior edge of a moving wave of patterning and cell type specification that 112 years later (1976) Ready, Hansen and Benzer would name the "morphogenetic furrow". While it is too late to hear from August Weismann, it is a particular pleasure to be able to include a chapter in this Volume from the first author of that 1976 paper: Don Ready! These past 25 years have seen an astonishing explosion in the study of the fly eye (see Fig.

Comprehensive Overview of Advances in OlfactionThe common belief is that human smell perception is much reduced compared with other mammals, so that whatever abilities are uncovered and investigated in animal research would have little significance for humans. However, new evidence from a variety of sources indicates this traditional view is likely