Página 1 dos resultados de 7913 itens digitais encontrados em 0.022 segundos

‣ Quantitative analysis of indexed publications on seventeen model organisms in nine countries, from 1974 to 2006

WINTER, Carlos E.
Fonte: JOHN WILEY & SONS INC Publicador: JOHN WILEY & SONS INC
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
463.21773%
Developed countries have an even distribution of published papers on the seventeen model organisms. Developing countries have biased preferences for a few model organisms which are associated with endemic human diseases. A variant of the Hirsch-index, that we call the mean (mo)h-index (""model organism h-index""), shows an exponential relationship with the amount of papers published in each country on the selected model organisms. Developing countries cluster together with low mean (mo)h-indexes, even those with high number of publications. The growth curves of publications on the recent model Caenorhabditis elegans in developed countries shows different formats. We also analyzed the growth curves of indexed publications originating from developing countries. Brazil and South Korea were selected for this comparison. The most prevalent model organisms in those countries show different growth curves when compared to a global analysis, reflecting the size and composition of their research communities.

‣ Genome wide mining of alternative splicing in metazoan model organisms

Mollet, Inês Maria de Stoop Camões Teixeira Guerra, 1966-
Fonte: Universidade de Lisboa Publicador: Universidade de Lisboa
Tipo: Tese de Doutorado
Publicado em //2009 Português
Relevância na Pesquisa
459.84414%
Tese de doutoramento, Ciências Biomédicas (Ciências Morfológicas), Universidade de Lisboa, Faculdade de Medicina, 2009; Background: Mining current mRNA and EST databases for novel alternatively spliced isoforms is of paramount importance for shedding light on the way in which the maturation of RNA is used to regulate gene expression. Preliminary observations revealed a tendency for greater amounts of potentially non protein-coding alternative transcripts in human genes than in orthologous genes from other organisms. However, many of these isoforms did not appear in recently published alternative splicing databases on account of constraints imposed in the selection of transcripts. This prompted us to develop a less constrained database with the aim of contributing to the identification of the full repertoire of splice variants in the transcriptome of different organisms. Given that mechanisms of control of gene expression involving non-protein-coding splice variants have been described in a variety of genes, this information may be crucial to deciphering more intricate layers of gene regulation in complex organisms brought about by alternative splicing. Description: An algorithm was developed to cluster mRNA and EST BLAT alignments to annotated gene regions. Consensus splice sites were the main requirement imposed on the selection of transcripts. The method was applied to thirteen model organisms. The alternative splicing information generated has been incorporated into a database with clear graphical displays representing the splicing patterns and is available from the ExonMine website (http://www.imm.fm.ul.pt/exonmine). It incorporates information on constitutive exons...

‣ SNPs by AFLP (SBA): a rapid SNP isolation strategy for non-model organisms

Nicod, Jean-Claude; Largiadèr, Carlo R.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em 01/03/2003 Português
Relevância na Pesquisa
459.15676%
Despite the great potential of single nucleotide polymorphism (SNP) markers in evolutionary studies, in particular for inferring population genetic parameters, SNP analysis has almost exclusively been limited to humans and ‘genomic model’ organisms, due to the lack of available sequence data in non-model organisms. Here, we describe a rapid and cost effective method to isolate candidate SNPs in non-model organisms. This SNP isolation strategy consists basically in the direct sequencing of amplified fragment length polymorphism bands. In a first application of this method, 10 unique DNA fragments that contained 24 SNPs were discovered in 11.11 kb of sequenced genomic DNA of a non-model species, the brown trout (Salmo trutta).

‣ Research on animal model organisms funded by the European Commission’s framework programmes

Desaintes, Christian
Fonte: The Company of Biologists Limited Publicador: The Company of Biologists Limited
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
Relevância na Pesquisa
462.01918%
Recognising the crucial role of model organisms in exploring the causes of human disease and in developing safe treatments, the European Commission has invested €180 million in collaborative research projects on model organisms since 2002. Further financial support is planned for the future. Projects supported by the European Commission are playing an important role in structuring the research landscape in Europe and creating the knowledge base to understand health and disease. Furthermore, they are generating important and freely available data and/or animal resources that will catalyse progress in biomedical research. This paper focuses on animal model organisms and includes the rodents, mouse and rat, other vertebrates such as zebrafish and frog, and also invertebrates such as nematodes. Research on other model organisms, including yeast, bacteria and plants, is also being supported and this is providing knowledge on basic cellular and molecular processes, as well as on host-microorganism interactions.

‣ NASCENT: An automatic protein interaction network generation tool for non-model organisms

Banky, Daniel; Ordog, Rafael; Grolmusz, Vince
Fonte: Biomedical Informatics Publishing Group Publicador: Biomedical Informatics Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 24/04/2009 Português
Relevância na Pesquisa
457.76176%
Large quantity of reliable protein interaction data are available for model organisms in public depositories (e.g., MINT, DIP, HPRD, INTERACT). Most data correspond to experiments with the proteins of Saccharomyces cerevisiae, Drosophila melanogaster, Homo sapiens, Caenorhabditis elegans, Escherichia coli and Mus musculus. For other important organisms the data availability is poor or non-existent. Here we present NASCENT, a completely automatic web-based tool and also a downloadable Java program, capable of modeling and generating protein interaction networks even for non-model organisms. The tool performs protein interaction network modeling through gene-name mapping, and outputs the resulting network in graphical form and also in computer-readable graph-forms, directly applicable by popular network modeling software.

‣ Quantitative Proteomics by Metabolic Labeling of Model Organisms*

Gouw, Joost W.; Krijgsveld, Jeroen; Heck, Albert J. R.
Fonte: The American Society for Biochemistry and Molecular Biology Publicador: The American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
462.459%
In the biological sciences, model organisms have been used for many decades and have enabled the gathering of a large proportion of our present day knowledge of basic biological processes and their derailments in disease. Although in many of these studies using model organisms, the focus has primarily been on genetics and genomics approaches, it is important that methods become available to extend this to the relevant protein level. Mass spectrometry-based proteomics is increasingly becoming the standard to comprehensively analyze proteomes. An important transition has been made recently by moving from charting static proteomes to monitoring their dynamics by simultaneously quantifying multiple proteins obtained from differently treated samples. Especially the labeling with stable isotopes has proved an effective means to accurately determine differential expression levels of proteins. Among these, metabolic incorporation of stable isotopes in vivo in whole organisms is one of the favored strategies. In this perspective, we will focus on methodologies to stable isotope label a variety of model organisms in vivo, ranging from relatively simple organisms such as bacteria and yeast to Caenorhabditis elegans, Drosophila, and Arabidopsis up to mammals such as rats and mice. We also summarize how this has opened up ways to investigate biological processes at the protein level in health and disease...

‣ Lessons from Model Organisms: Phenotypic Robustness and Missing Heritability in Complex Disease

Queitsch, Christine; Carlson, Keisha D.; Girirajan, Santhosh
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
464.0865%
Genetically tractable model organisms from phages to mice have taught us invaluable lessons about fundamental biological processes and disease-causing mutations. Owing to technological and computational advances, human biology and the causes of human diseases have become accessible as never before. Progress in identifying genetic determinants for human diseases has been most remarkable for Mendelian traits. In contrast, identifying genetic determinants for complex diseases such as diabetes, cancer, and cardiovascular and neurological diseases has remained challenging, despite the fact that these diseases cluster in families. Hundreds of variants associated with complex diseases have been found in genome-wide association studies (GWAS), yet most of these variants explain only a modest amount of the observed heritability, a phenomenon known as “missing heritability.” The missing heritability has been attributed to many factors, mainly inadequacies in genotyping and phenotyping. We argue that lessons learned about complex traits in model organisms offer an alternative explanation for missing heritability in humans. In diverse model organisms, phenotypic robustness differs among individuals, and those with decreased robustness show increased penetrance of mutations and express previously cryptic genetic variation. We propose that phenotypic robustness also differs among humans and that individuals with lower robustness will be more responsive to genetic and environmental perturbations and hence susceptible to disease. Phenotypic robustness is a quantitative trait that can be accurately measured in model organisms...

‣ Bacteria, Yeast, Worms, and Flies: Exploiting simple model organisms to investigate human mitochondrial diseases

Rea, Shane L.; Graham, Brett H.; Nakamaru-Ogiso, Eiko; Kar, Adwitiya; Falk, Marni J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/2010 Português
Relevância na Pesquisa
458.46984%
The extensive conservation of mitochondrial structure, composition, and function across evolution offers a unique opportunity to expand our understanding of human mitochondrial biology and disease. By investigating the biology of much simpler model organisms, it is often possible to answer questions that are unreachable at the clinical level. Here, we review the relative utility of four different model organisms, namely the bacteria Escherichia coli, the yeast Saccharomyces cerevisiae, the nematode Caenorhabditis elegans and the fruit fly Drosophila melanogaster, in studying the role of mitochondrial proteins relevant to human disease. E. coli are single cell, prokaryotic bacteria that have proven to be a useful model system in which to investigate mitochondrial respiratory chain protein structure and function. S. cerevisiae is a single-celled eukaryote that can grow equally well by mitochondrial-dependent respiration or by ethanol fermentation, a property that has proven to be a veritable boon for investigating mitochondrial functionality. C. elegans is a multi-cellular, microscopic worm that is organized into five major tissues and has proven to be a robust model animal for in vitro and in vivo studies of primary respiratory chain dysfunction and its potential therapies in humans. Studied for over a century...

‣ Unlocking the potential of survival data for model organisms through a new database and online analysis platform: SurvCurv

Ziehm, Matthias; Thornton, Janet M
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
460.1018%
Lifespan measurements, also called survival records, are a key phenotype in research on aging. If external hazards are excluded, aging alone determines the mortality in a population of model organisms. Understanding the biology of aging is highly desirable because of the benefits for the wide range of aging-related diseases. However, it is also extremely challenging because of the underlying complexity. Here, we describe SurvCurv, a new database and online resource focused on model organisms collating survival data for storage and analysis. All data in SurvCurv are manually curated and annotated. The database, available at http://www.ebi.ac.uk/thornton-srv/databases/SurvCurv/, offers various functions including plotting, Cox proportional hazards analysis, mathematical mortality models and statistical tests. It facilitates reanalysis and allows users to analyse their own data and compare it with the largest repository of model-organism data from published experiments, thus unlocking the potential of survival data and demographics in model organisms.

‣ ezRAD: a simplified method for genomic genotyping in non-model organisms

Toonen, Robert J.; Puritz, Jonathan B.; Forsman, Zac H.; Whitney, Jonathan L.; Fernandez-Silva, Iria; Andrews, Kimberly R.; Bird, Christopher E.
Fonte: PeerJ Inc. Publicador: PeerJ Inc.
Tipo: Artigo de Revista Científica
Publicado em 19/11/2013 Português
Relevância na Pesquisa
459.15676%
Here, we introduce ezRAD, a novel strategy for restriction site–associated DNA (RAD) that requires little technical expertise or investment in laboratory equipment, and demonstrate its utility for ten non-model organisms across a wide taxonomic range. ezRAD differs from other RAD methods primarily through its use of standard Illumina TruSeq library preparation kits, which makes it possible for any laboratory to send out to a commercial genomic core facility for library preparation and next-generation sequencing with virtually no additional investment beyond the cost of the service itself. This simplification opens RADseq to any lab with the ability to extract DNA and perform a restriction digest. ezRAD also differs from others in its flexibility to use any restriction enzyme (or combination of enzymes) that cuts frequently enough to generate fragments of the desired size range, without requiring the purchase of separate adapters for each enzyme or a sonication step, which can further decrease the cost involved in choosing optimal enzymes for particular species and research questions. We apply this method across a wide taxonomic diversity of non-model organisms to demonstrate the utility and flexibility of our approach. The simplicity of ezRAD makes it particularly useful for the discovery of single nucleotide polymorphisms and targeted amplicon sequencing in natural populations of non-model organisms that have been historically understudied because of lack of genomic information.

‣ Model Organisms and Traditional Chinese Medicine Syndrome Models

Ling, Shuang; Xu, Jin-Wen
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
463.94625%
Traditional Chinese medicine (TCM) is an ancient medical system with a unique cultural background. Nowadays, more and more Western countries due to its therapeutic efficacy are accepting it. However, safety and clear pharmacological action mechanisms of TCM are still uncertain. Due to the potential application of TCM in healthcare, it is necessary to construct a scientific evaluation system with TCM characteristics and benchmark the difference from the standard of Western medicine. Model organisms have played an important role in the understanding of basic biological processes. It is easier to be studied in certain research aspects and to obtain the information of other species. Despite the controversy over suitable syndrome animal model under TCM theoretical guide, it is unquestionable that many model organisms should be used in the studies of TCM modernization, which will bring modern scientific standards into mysterious ancient Chinese medicine. In this review, we aim to summarize the utilization of model organisms in the construction of TCM syndrome model and highlight the relevance of modern medicine with TCM syndrome animal model. It will serve as the foundation for further research of model organisms and for its application in TCM syndrome model.

‣ Model Organisms Retain an “Ecological Memory” of Complex Ecologically Relevant Environmental Variation

Beer, Karlyn D.; Wurtmann, Elisabeth J.; Pinel, Nicolás; Baliga, Nitin S.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /03/2014 Português
Relevância na Pesquisa
459.15676%
Although tractable model organisms are essential to characterize the molecular mechanisms of evolution and adaptation, the ecological relevance of their behavior is not always clear because certain traits are easily lost during long-term laboratory culturing. Here, we demonstrate that despite their long tenure in the laboratory, model organisms retain “ecological memory” of complex environmental changes. We have discovered that Halobacterium salinarum NRC-1, a halophilic archaeon that dominates microbial communities in a dynamically changing hypersaline environment, simultaneously optimizes fitness to total salinity, NaCl concentration, and the [K]/[Mg] ratio. Despite being maintained under controlled conditions over the last 50 years, peaks in the three-dimensional fitness landscape occur in salinity and ionic compositions that are not replicated in laboratory culturing but are routinely observed in the natural hypersaline environment of this organism. Intriguingly, adaptation to variations in ion composition was associated with differential regulation of anaerobic metabolism genes, suggesting an intertwined relationship between responses to oxygen and salinity. Our results suggest that the ecological memory of complex environmental variations is imprinted in the networks for coordinating multiple cellular processes. These coordination networks are also essential for dealing with changes in other physicochemically linked factors present during routine laboratory culturing and...

‣ Absence/presence calling in microarray-based CGH experiments with non-model organisms

Jonker, Martijs J.; de Leeuw, Wim C.; Marinković, Marino; Wittink, Floyd R. A.; Rauwerda, Han; Bruning, Oskar; Ensink, Wim A.; Fluit, Ad C.; Boel, C. H.; de Jong, Mark; Breit, Timo M.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
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459.15676%
Structural variations in genomes are commonly studied by (micro)array-based comparative genomic hybridization. The data analysis methods to infer copy number variation in model organisms (human, mouse) are established. In principle, the procedures are based on signal ratios between test and reference samples and the order of the probe targets in the genome. These procedures are less applicable to experiments with non-model organisms, which frequently comprise non-sequenced genomes with an unknown order of probe targets. We therefore present an additional analysis approach, which does not depend on the structural information of a reference genome, and quantifies the presence or absence of a probe target in an unknown genome. The principle is that intensity values of target probes are compared with the intensities of negative-control probes and positive-control probes from a control hybridization, to determine if a probe target is absent or present. In a test, analyzing the genome content of a known bacterial strain: Staphylococcus aureus MRSA252, this approach proved to be successful, demonstrated by receiver operating characteristic area under the curve values larger than 0.9995. We show its usability in various applications, such as comparing genome content and validating next-generation sequencing reads from eukaryotic non-model organisms.

‣ Compound prioritization methods increase rates of chemical probe discovery in model organisms

Wallace, Iain M; Urbanus, Malene L; Luciani, Genna M; Burns, Andrew R; Han, Mitchell KL; Wang, Hao; Arora, Kriti; Heisler, Lawrence E; Proctor, Michael; St. Onge, Robert P; Roemer, Terry; Roy, Peter J; Cummins, Carolyn L; Bader, Gary D; Nislow, Corey; Gia
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 28/10/2011 Português
Relevância na Pesquisa
458.46984%
Pre-selection of compounds that are more likely to induce a phenotype can increase the efficiency and reduce the costs for model organism screening. To identify such molecules, we screened ~81,000 compounds in S. cerevisiae and identified ~7,500 that inhibit cell growth. Screening these growth-inhibitory molecules across a diverse panel of model organisms resulted in an increased phenotypic hit-rate. This data was used to build a model to predict compounds that inhibit yeast growth. Empirical and in silico application of the model enriched the discovery of bioactive compounds in diverse model organisms. To demonstrate the potential of these molecules as lead chemical probes we used chemogenomic profiling in yeast and identified specific inhibitors of lanosterol synthase and of stearoyl-CoA 9-desaturase. As community resources, the ~7,500 growth-inhibitory molecules has been made commercially available and the computational model and filter used are provided.

‣ What RNAi screens in model organisms revealed about microbicidal response in mammals?

Abnave, Prasad; Conti, Filippo; Torre, Cedric; Ghigo, Eric
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 12/01/2015 Português
Relevância na Pesquisa
463.404%
The strategies evolved by pathogens to infect hosts and the mechanisms used by the host to eliminate intruders are highly complex. Because several biological pathways and processes are conserved across model organisms, these organisms have been used for many years to elucidate and understand the mechanisms of the host-pathogen relationship and particularly to unravel the molecular processes enacted by the host to kill pathogens. The emergence of RNA interference (RNAi) and the ability to apply it toward studies in model organisms have allowed a breakthrough in the elucidation of host-pathogen interactions. The aim of this mini-review is to highlight and describe recent breakthroughs in the field of host-pathogen interactions using RNAi screens of model organisms. We will focus specifically on the model organisms Drosophila melanogaster, Caenorhabditis elegans, and Danio rerio. Moreover, a recent study examining the immune system of planarian will be discussed.

‣ Wormy logic: model organisms as case-based reasoning

Ankeny, Rachel Allyson
Fonte: London School of Economics and Political Science Publicador: London School of Economics and Political Science
Tipo: Relatório
Publicado em //2006 Português
Relevância na Pesquisa
462.7017%
In the past few decades, so-called model organisms have become a cornerstone of research in the biomedical sciences. For the scientists, the model organism is both a practice ground for developing laboratory techniques, and a source of insights into common or even universal biological mechanisms. This paper examines the conceptualization of model organisms as models, and presents a formal account of how they are used to generate knowledge through what can be viewed as a form of case-based reasoning. Case-based reasoning is an epistemic process that is far from straightforward and may seem to fail to allow us to obtain the usual results we expect in science. Meanwhile, a growing literature within the history and philosophy of science on modelling and representation creates a space within which close attention to the principles and practices associated with such models may prove fruitful. Following a brief historical account of the development and use of one model organism, the nematode worm Caenorhabditis elegans, this paper addresses questions about the methodologies underlying work on genetic sequencing and developmental processes in this organism. In particular, what types of reasoning ground the use of experimental organisms when they are being developed and used as model organisms...

‣ Re-thinking organisms: The impact of databases on model organism biology

Leonelli, S.; Ankeny, R.
Fonte: Pergamon Publicador: Pergamon
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
Relevância na Pesquisa
457.9538%
Community databases have become crucial to the collection, ordering and retrieval of data gathered on model organisms, as well as to the ways in which these data are interpreted and used across a range of research contexts. This paper analyses the impact of community databases on research practices in model organism biology by focusing on the history and current use of four community databases: FlyBase, Mouse Genome Informatics, WormBase and The Arabidopsis Information Resource. We discuss the standards used by the curators of these databases for what counts as reliable evidence, acceptable terminology, appropriate experimental set-ups and adequate materials (e.g., specimens). On the one hand, these choices are informed by the collaborative research ethos characterising most model organism communities. On the other hand, the deployment of these standards in databases reinforces this ethos and gives it concrete and precise instantiations by shaping the skills, practices, values and background knowledge required of the database users. We conclude that the increasing reliance on community databases as vehicles to circulate data is having a major impact on how researchers conduct and communicate their research, which affects how they understand the biology of model organisms and its relation to the biology of other species.; Sabina Leonelli...

‣ De novo transcriptome assembly for a non-model species, the blood-sucking bug Triatoma brasiliensis, a vector of Chagas disease

Marchant, A.; Mougel, F.; Almeida, C.; Jacquin-Joly, E.; Costa, J.; Harry, M.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 225-239
Português
Relevância na Pesquisa
550.33176%
High throughput sequencing (HTS) provides new research opportunities for work on non-model organisms, such as differential expression studies between populations exposed to different environmental conditions. However, such transcriptomic studies first require the production of a reference assembly. The choice of sampling procedure, sequencing strategy and assembly workflow is crucial. To develop a reliable reference transcriptome for Triatoma brasiliensis, the major Chagas disease vector in Northeastern Brazil, different de novo assembly protocols were generated using various datasets and software. Both 454 and Illumina sequencing technologies were applied on RNA extracted from antennae and mouthparts from single or pooled individuals. The 454 library yielded 278 Mb. Fifteen Illumina libraries were constructed and yielded nearly 360 million RNA-seq single reads and 46 million RNA-seq paired-end reads for nearly 45 Gb. For the 454 reads, we used three assemblers, Newbler, CAP3 and/or MIRA and for the Illumina reads, the Trinity assembler. Ten assembly workflows were compared using these programs separately or in combination. To compare the assemblies obtained, quantitative and qualitative criteria were used, including contig length...

‣ Peromyscus mice as a model for studying natural variation

Bedford, Nicole L; Hoekstra, Hopi E
Fonte: eLife Sciences Publications, Ltd Publicador: eLife Sciences Publications, Ltd
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
556.3263%
The deer mouse (genus Peromyscus) is the most abundant mammal in North America, and it occupies almost every type of terrestrial habitat. It is not surprising therefore that the natural history of Peromyscus is among the best studied of any small mammal. For decades, the deer mouse has contributed to our understanding of population genetics, disease ecology, longevity, endocrinology and behavior. Over a century's worth of detailed descriptive studies of Peromyscus in the wild, coupled with emerging genetic and genomic techniques, have now positioned these mice as model organisms for the study of natural variation and adaptation. Recent work, combining field observations and laboratory experiments, has lead to exciting advances in a number of fields—from evolution and genetics, to physiology and neurobiology. DOI: http://dx.doi.org/10.7554/eLife.06813.001

‣ Wormy logic: model organisms as case-based reasoning

Ankeny, Rachel A.
Fonte: Department of Economic History, London School of Economics and Political Science Publicador: Department of Economic History, London School of Economics and Political Science
Tipo: Monograph; NonPeerReviewed Formato: application/pdf
Publicado em /03/2006 Português
Relevância na Pesquisa
462.7017%
In the past few decades, so-called model organisms have become a cornerstone of research in the biomedical sciences. For the scientists, the model organism is both a practice ground for developing laboratory techniques, and a source of insights into common or even universal biological mechanisms. This paper examines the conceptualization of model organisms as models, and presents a formal account of how they are used to generate knowledge through what can be viewed as a form of case-based reasoning. Case-based reasoning is an epistemic process that is far from straightforward and may seem to fail to allow us to obtain the usual results we expect in science. Meanwhile, a growing literature within the history and philosophy of science on modelling and representation creates a space within which close attention to the principles and practices associated with such models may prove fruitful. Following a brief historical account of the development and use of one model organism, the nematode worm Caenorhabditis elegans, this paper addresses questions about the methodologies underlying work on genetic sequencing and developmental processes in this organism. In particular, what types of reasoning ground the use of experimental organisms when they are being developed and used as model organisms...