Identification of Novel (RNAi Deficient) Genes in C. Elegans PDF Download
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Author: Chun-Chieh G. Chen
Publisher:
ISBN:
Category :
Languages : en
Pages : 308
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Author: Chun-Chieh G. Chen
Publisher:
ISBN:
Category :
Languages : en
Pages : 308
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Author: Mitchell Lee
Publisher:
ISBN:
Category : Caenorhabditis elegans
Languages : en
Pages : 202
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Author: Fei Xie
Publisher:
ISBN:
Category :
Languages : en
Pages : 110
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Author: Juan E. Abrahante Lloréns
Publisher:
ISBN:
Category :
Languages : en
Pages : 406
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Author: George Frederick Spracklin IV
Publisher:
ISBN:
Category :
Languages : en
Pages : 140
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Small RNAs can regulate gene expression in eukaryotes. During RNA interference (RNAi), small RNAs are bound by Argonaute proteins and act as guide molecules to silence cellular RNAs. In C. elegans, RNAi silencing can persist for 6-10 generations in the absence of the initial trigger (termed RNAi inheritance). RNAi inheritance requires the nuclear RNAi factors NRDE-1/-2/-4 highlighting the importance of co-transcriptional gene silencing and heterochromatin formation in heritable gene silencing by dsRNA. This thesis explores how gene silencing propagates across generations by identifying and characterizing cellular factors required for RNAi inheritance in the model organism C. elegans. Chapter 2 of this thesis identifies six novel components of the RNAi inheritance machinery whose sequence conservation provides insights into the molecular mechanism of RNAi inheritance and strengthens the correlation between RNAi inheritance and germline immortality. Chapter 2 also demonstrates that HRDE-2 promotes RNAi inheritance by coupling the inheritance Ago HRDE-1 with the small RNAs it needs to direct RNAi inheritance and germline immortality.
Author: Ian A. Hope
Publisher: OUP Oxford
ISBN: 019159198X
Category : Science
Languages : en
Pages : 306
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Caenorhabditis Elegans has been a popular model organism for biological research for over thirty years and has been used to investigate many aspects of animal development, for example apoptosis, the Hox genes, signal transduction pathways, and the development of the nervous system. It has recently taken on new importance with the publication of the entire genome sequence in 1998. The first chapter gives all the basic information on C. elegans required to use it: it's natural history, anatomy, life cycle, development, and evolution. Information on how to obtain, grow, and maintain C. elegans for use as a model system is given in Chapter 4. Chapters 2 and 3 describe the genome project and show how to use genome sequence information by searching the database for homologues using different search methods and then how to analyse the search data. The next chapter gives the essential practical details of transformation and common uses for the technique. Chapter 6 covers reverse genetics and describes strategies for gene inactivation that are known to work in C elegans: epigenetic inactivation and mutational germ line inactivation. Chapter 7 is designed to help the user analyse phenotype by microscopy and includes Normaski, fluorescence, 4-dimensional, and electron microscopy. Techniques for studying the neurobiology of C. elegans are given in chapter 8. Chapter 9 describes the three commonly used approaches for studying gene expression and Chapter 10 deals with the common methods of molecular biology essential for gene characterization. C. elegans is not the ideal organism for biochemical studies, but chapter 11 describes several procedures for producing biochemically useful quantities of pure tissues. The final chapter is about conventional genetics and details the standard procedures for selfing and crossing; mutagenesis and mutant screening; characterization of mutants; gene mapping; temperature-shift experiments and mosaic analysis. Caenorhabditis Elegans: A Practical Approach will therefore provide all the background information necessary for use of C. elegans as a model system.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 151
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Small RNAs can regulate the expression of other cellular RNAs. RNA interference is a process by which small RNAs `silence' genes by inhibiting transcription or degrading messenger RNAs, preventing the gene from making functional products. RNAi induced silencing is epigenetic, the DNA sequence is left unaltered. Interestingly, RNAi induced silencing can be heritable for multiple generations. The nematode C. elegans is the perfect model for studying this epigenetic phenomenon C. elegans are amenable to RNAi and RNAi induced silencing of genes in the germ line can be heritable for many (>10) generations. This thesis aims to better understand the mechanism and genetics of RNAi inheritance in the C. elegans germ line. Chapter 2 of this thesis presents the identification of a novel nuclear Ago that promotes germline RNAi inheritance. Chapter 2 also highlights the importance of nuclear silencing in multigenerational RNAi inheritance and suggests that heterochromatin and siRNAs might act as heritable agents of RNAi memory. RNAi inheritance does not last forever. Chapter 3 explores the idea that the reason RNAi inheritance does not last forever might be because it is under negative regulation. Chapter 3 presents preliminary results from a forward genetic screen that was conducted to identify mutants in which RNAi inheritance is no longer limited and RNAi silencing can essentially become permanent.
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Languages : en
Pages :
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This study was undertaken to identify genes involved in axon guidance in the nervous system of Caenorabditis elegans. Due to its unique physiological properties, the nematode worm C. elegans is a powerful genetic model system to study a variety of biological processes. The nervous system of C. elegans is a simple organ comprising 302 neurons. These neurons create stereotypic neuronal networks formed by their anterior-posterior and dorsal-ventral running axons. Here, we took advantage of the recently discovered phenomenon of RNA interference in the worm to identify axon guidance genes. However, the nervous system of C. elegans is refractory to the systemic RNA interference, and delivery of dsRNA molecules to the neighboring non-neuronal cells does not initiate RNAi in the neurons of the worm. Therefore, we started with the identification of mutants of C. elegans that are efficient for RNAi in the nervous system. A standard chemical mutagenesis screen was performed to identify mutants of the worm that showed enhanced RNAi efficiency in the nervous system. One of the mutants (nre-1, for neuronal RNAi efficient) showed marked suppression of gene expression in the nervous system by feeding RNAi approach. We used the nre-1 supersensitive strain as a tool in a reverse genetic screen to identify genes required for axon guidance in C. elegans. A transgenic strain was constructed in the nre-1 background, wherein a subset of interneurons and motor neurons were labeled with the yellow fluorescent protein to visualize axons of the neurons. We used this strain to screen 2416 gene of the worm located on chromosome I by feeding a library of bacterial clones expressing dsRNA fragments specific to the genes. This screen has identified 57 candidate genes that give rise to penetrant axon guidance defects in the commissural and ventral nerve cord axons in C. elegans. The genes identified include genes involved in various cellular processes such as DNA metabolism, translation, transcript.
Author: Jerry J. Buccafusco
Publisher: CRC Press
ISBN: 1420041819
Category : Medical
Languages : en
Pages : 341
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Book Description
Using the most well-studied behavioral analyses of animal subjects to promote a better understanding of the effects of disease and the effects of new therapeutic treatments on human cognition, Methods of Behavior Analysis in Neuroscience provides a reference manual for molecular and cellular research scientists in both academia and the pharmaceutic
Author: Zhaozhao Qin
Publisher:
ISBN:
Category :
Languages : en
Pages : 164
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For over 30 years, researchers have taken advantage of genetic balancers and forward genetic screens to isolate lethal mutations, which have been studied to identify essential genes in C. elegans. Using traditional genetic methods, such as genetic mapping, complementation tests, and transgenic rescue assays, many essential genes have been successfully identified. However, to pinpoint a specific essential gene the involved experiments are usually labor intensive and time consuming. Nowadays, genetic methods combined with whole genome sequencing (WGS) and bioinformatics analysis provide an effective approach for the molecular identification of essential genes. In my thesis I successfully identified 64 new essential genes with 107 lethal mutations in genomic regions of C. elegans of around 14 Mb from Chromosome III(mid) and Chromosome V(left), by combining genetic mapping, Illumina sequencing, bioinformatics analyses, and experimental validation. Most of these genes have multiple recovered mutant alleles. Of these 64 genes 5 have new alleles identified, which had not been previously studied by RNA interference depletion. Furthermore, by investigating the locations of lethal missense mutations in essential genes, I have identified five novel protein functional domains. Functional characterization of the identified essential genes shows that most of them are enzymes, including helicases, tRNA synthetase, and kinases. There are also ribosomal proteins. Gene Ontology functional annotation also indicates that essential genes tend to execute enzyme and nucleic acid binding activities during fundamental processes, such as intracellular protein synthesis. Essential gene analysis shows that compared to non-essential genes, essential genes have fewer paralogs, and encode proteins that are in protein interaction hubs. Essential genes are also more abundantly and consistently expressed over all developmental stages than non-essential genes. All these essential genes traits in C. elegans are consistent with those of human disease genes. Unsurprisingly, most (90%) human orthologs of essential genes in this study are related to human diseases. Therefore, functional characterization of essential genes underlines their importance as proxies for understanding the biological functions of human disease genes.
