Integrative Physiology and Functional Genomics of Epithelial Function in  a Genetic Model Organism

Dow, Julian A. T, and Shireen A. Davies. Integrative Physiology and Functional Genomics of Epithelial Function in a Genetic Model Organism. Physiol Rev 83: 687–729, 2003; 10.1152/physrev.00035.2002.—Classically, biologists try to understand their complex systems by simplifying them to a level where the problem is tractable, typically moving from whole animal and organ-level biology to the immensely powerful “cellular” and “molecular” approaches. However, the limitations of this reductionist approach are becoming apparent, leading to calls for a new, “integrative” physiology. Rather than use the term as a rallying cry for classical organismal physiology, we have defined it as the study of how gene products integrate into the function of whole tissues and intact organisms. From this viewpoint, the convergence between integrative physiology and functional genomics becomes clear; both seek to understand gene function in an organismal context, and both draw heavily on transgenics and genetics in genetic models to achieve their goal. This convergence between historically divergent fields provides powerful leverage to those physiologists who can phrase their research questions in a particular way. In particular, the use of appropriate genetic model organisms provides a wealth of technologies (of which microarrays and knock-outs are but two) that allow a new precision in physiological analysis. We illustrate this approach with an epithelial model system, the Malpighian (renal) tubule of Drosophila melanogaster. With the use of the beautiful genetic tools and extensive genomic resources characteristic of this genetic model, it has been possible to gain unique insights into the structure, function, and control of epithelia.

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Rest Is Required to Learn an Appetitively-Reinforced Operant Task in Drosophila

Frontiers in Behavioral Neuroscience ◽

10.3389/fnbeh.2021.681593 ◽

2021 ◽

Vol 15 ◽

Author(s):

Timothy D. Wiggin ◽

Yungyi Hsiao ◽

Jeffrey B. Liu ◽

Robert Huber ◽

Leslie C. Griffith

Keyword(s):

Operant Conditioning ◽

Molecular Mechanisms ◽

Genetic Model ◽

Model Organism ◽

Fruit Fly ◽

Model Organisms ◽

Valuable Insight ◽

Reward Contingency ◽

Neural Basis ◽

Operant Task

Maladaptive operant conditioning contributes to development of neuropsychiatric disorders. Candidate genes have been identified that contribute to this maladaptive plasticity, but the neural basis of operant conditioning in genetic model organisms remains poorly understood. The fruit fly Drosophila melanogaster is a versatile genetic model organism that readily forms operant associations with punishment stimuli. However, operant conditioning with a food reward has not been demonstrated in flies, limiting the types of neural circuits that can be studied. Here we present the first sucrose-reinforced operant conditioning paradigm for flies. In the paradigm, flies walk along a Y-shaped track with reward locations at the terminus of each hallway. When flies turn in the reinforced direction at the center of the track, they receive a sucrose reward at the end of the hallway. Only flies that rest early in training learn the reward contingency normally. Flies rewarded independently of their behavior do not form a learned association but have the same amount of rest as trained flies, showing that rest is not driven by learning. Optogenetically-induced sleep does not promote learning, indicating that sleep itself is not sufficient for learning the operant task. We validated the sensitivity of this assay to detect the effect of genetic manipulations by testing the classic learning mutant dunce. Dunce flies are learning-impaired in the Y-Track task, indicating a likely role for cAMP in the operant coincidence detector. This novel training paradigm will provide valuable insight into the molecular mechanisms of disease and the link between sleep and learning.

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From Genes to Integrative Physiology: Ion Channel and Transporter Biology in Caenorhabditis elegans

Physiological Reviews ◽

10.1152/physrev.00025.2002 ◽

2003 ◽

Vol 83 (2) ◽

pp. 377-415 ◽

Cited By ~ 55

Author(s):

Kevin Strange

Keyword(s):

Molecular Biology ◽

Information Flow ◽

Gene Function ◽

Transport Processes ◽

Model Organisms ◽

Reverse Genetic ◽

Integrative Physiology ◽

C Elegans ◽

Physiological Research ◽

Reductionist Approach

The stunning progress in molecular biology that has occurred over the last 50 years drove a powerful reductionist approach to the study of physiology. That same progress now forms the foundation for the next revolution in physiological research. This revolution will be focused on integrative physiology, which seeks to understand multicomponent processes and the underlying pathways of information flow from an organism's “parts” to increasingly complex levels of organization. Genetically tractable and genomically defined nonmammalian model organisms such as the nematode Caenorhabditis elegansprovide powerful experimental advantages for elucidating gene function and the molecular workings of complex systems. This review has two main goals. The first goal is to describe the experimental utility of C. elegans for investigating basic physiological problems. A detailed overview of C. elegans biology and the experimental tools, resources, and strategies available for its study is provided. The second goal of this review is to describe how forward and reverse genetic approaches and direct behavioral and physiological measurements in C. elegans have generated novel insights into the integrative physiology of ion channels and transporters. Where appropriate, I describe how insights from C. elegans have provided new understanding of the physiology of membrane transport processes in mammals.

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Molecular characterization of frog vocal neurons using constellation pharmacology

Journal of Neurophysiology ◽

10.1152/jn.00105.2020 ◽

2020 ◽

Author(s):

Ryota Thomas Inagaki ◽

Shrinivasan Raghuraman ◽

Kevin Chase ◽

Theresa Steele ◽

Erik Zornik ◽

...

Keyword(s):

Genetic Model ◽

Ex Vivo ◽

Model Organism ◽

Neuronal Cell ◽

Model Organisms ◽

Neural Basis ◽

Specific Expression ◽

Vocal Production ◽

Similar Frequency

Identification and characterization of neuronal cell classes in motor circuits are essential for understanding the neural basis of behavior. It is a challenging task, especially in a non-genetic model organism, to identify cell-specific expression of functional macromolecules. Here, we performed constellation pharmacology, calcium imaging of dissociated neurons to pharmacologically identify functional receptors expressed by vocal neurons in adult male and female African clawed frogs, Xenopus laevis. Previously we identified a population of vocal neurons called fast trill neurons (FTNs) in the amphibian parabrachial nucleus (PB) that express NMDA receptors and GABA and/or glycine receptors. Using constellation pharmacology, we identified four cell classes of putative fast trill neurons (pFTNs, responsive to both NMDA and GABA/glycine applications). We discovered that some pFTNs responded to the application of substance P (SP), acetylcholine (ACh), or both. Electrophysiological recordings obtained from FTNs using an ex vivo preparation verified that SP and/or ACh depolarize FTNs. Bilateral injection of ACh, SP, or their antagonists into PBs showed that ACh receptors are not sufficient but necessary for vocal production, and SP receptors play a role in shaping the morphology of vocalizations. Additionally, we discovered that the PB of adult female X. laevis also contains all the subclasses of neurons at a similar frequency as in males, despite their sexually distinct vocalizations. These results reveal novel neuromodulators that regulate X. laevis vocal production, and demonstrate the power of constellation pharmacology in identifying the neuronal subtypes marked by functional expression of cell-specific receptors in non-genetic model organisms.

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Semantic Multi-Classifier Systems Identify Predictive Processes in Heart Failure Models across Species

Biomolecules ◽

10.3390/biom8040158 ◽

2018 ◽

Vol 8 (4) ◽

pp. 158

Author(s):

Ludwig Lausser ◽

Lea Siegle ◽

Wolfgang Rottbauer ◽

Derk Frank ◽

Steffen Just ◽

...

Keyword(s):

Heart Failure ◽

Regulatory Networks ◽

Large Scale ◽

Genetic Model ◽

Model Organism ◽

Model Organisms ◽

Classifier Systems ◽

Experimental Conditions ◽

Kegg Pathways ◽

High Level

Genetic model organisms have the potential of removing blind spots from the underlying gene regulatory networks of human diseases. Allowing analyses under experimental conditions they complement the insights gained from observational data. An inevitable requirement for a successful trans-species transfer is an abstract but precise high-level characterization of experimental findings. In this work, we provide a large-scale analysis of seven weak contractility/heart failure genotypes of the model organism zebrafish which all share a weak contractility phenotype. In supervised classification experiments, we screen for discriminative patterns that distinguish between observable phenotypes (homozygous mutant individuals) as well as wild-type (homozygous wild-types) and carriers (heterozygous individuals). As the method of choice we use semantic multi-classifier systems, a knowledge-based approach which constructs hypotheses from a predefined vocabulary of high-level terms (e.g., Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways or Gene Ontology (GO) terms). Evaluating these models leads to a compact description of the underlying processes and guides the screening for new molecular markers of heart failure. Furthermore, we were able to independently corroborate the identified processes in Wistar rats.

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The rise to dominance of genetic model organisms and the decline of curiosity-driven organismal research

PLoS ONE ◽

10.1371/journal.pone.0243088 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0243088

Author(s):

Sarah M. Farris

Keyword(s):

Biological Sciences ◽

Genetic Model ◽

Model Organism ◽

National Institutes Of Health ◽

Model Organisms ◽

Biological Research ◽

Health It ◽

Living Things ◽

Evolutionary Context ◽

Diversity Of Life

Curiosity-driven, basic biological research “…performed without thought of practical ends…” establishes fundamental conceptual frameworks for future technological and medical breakthroughs. Traditionally, curiosity-driven research in biological sciences has utilized experimental organisms chosen for their tractability and suitability for studying the question of interest. This approach leverages the diversity of life to uncover working solutions (adaptations) to problems encountered by living things, and evolutionary context as to the extent to which these solutions may be generalized to other species. Despite the well-documented success of this approach, funding portfolios of United States granting agencies are increasingly filled with studies on a few species for which cutting-edge molecular tools are available (genetic model organisms). While this narrow focus may be justified for biomedically-focused funding bodies such as the National Institutes of Health, it is critical that robust federal support for curiosity-driven research using diverse experimental organisms be maintained by agencies such as the National Science Foundation. Using the disciplines of neurobiology and behavioral research as an example, this study finds that NSF grant awards have declined in association with a decrease in the proportion of grants funded for experimental, rather than genetic model organism research. The decline in use of experimental organisms in the literature mirrors but predates the shift grant funding. Today’s dominance of genetic model organisms was thus initiated by researchers themselves and/or by publication peer review and editorial preferences, and was further reinforced by pressure from granting agencies, academic employers, and the scientific community.

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The fruit fly at the interface of diagnosis and pathogenic mechanisms of rare and common human diseases

Human Molecular Genetics ◽

10.1093/hmg/ddz135 ◽

2019 ◽

Vol 28 (R2) ◽

pp. R207-R214 ◽

Cited By ~ 14

Author(s):

Hugo J Bellen ◽

Michael F Wangler ◽

Shinya Yamamoto

Keyword(s):

Rare Disease ◽

Gene Function ◽

Rare Variants ◽

Genetic Model ◽

Model Organism ◽

Model Organisms ◽

Pathogenic Mechanisms ◽

Disease Mechanisms ◽

The Impact ◽

Undiagnosed Diseases

Abstract Drosophila melanogaster is a unique, powerful genetic model organism for studying a broad range of biological questions. Human studies that probe the genetic causes of rare and undiagnosed diseases using massive-parallel sequencing often require complementary gene function studies to determine if and how rare variants affect gene function. These studies also provide inroads to disease mechanisms and therapeutic targets. In this review we discuss strategies for functional studies of rare human variants in Drosophila. We focus on our experience in establishing a Drosophila core of the Model Organisms Screening Center for the Undiagnosed Diseases Network (UDN) and concurrent fly studies with other large genomic rare disease research efforts such as the Centers for Mendelian Genomics. We outline four major strategies that use the latest technology in fly genetics to understand the impact of human variants on gene function. We also mention general concepts in probing disease mechanisms, therapeutics and using rare disease to understand common diseases. Drosophila is and will continue to be a fundamental genetic model to identify new disease-causing variants, pathogenic mechanisms and drugs that will impact medicine.

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In Search of Species-Specific SNPs in a Non-Model Animal (European Bison (Bison bonasus))—Comparison of De Novo and Reference-Based Integrated Pipeline of STACKS Using Genotyping-by-Sequencing (GBS) Data

Animals ◽

10.3390/ani11082226 ◽

2021 ◽

Vol 11 (8) ◽

pp. 2226

Author(s):

Sazia Kunvar ◽

Sylwia Czarnomska ◽

Cino Pertoldi ◽

Małgorzata Tokarska

Keyword(s):

Reference Genome ◽

De Novo ◽

Bos Taurus ◽

Model Organism ◽

Genotyping By Sequencing ◽

Model Organisms ◽

European Bison ◽

Model Animal ◽

Pcr Duplicates ◽

Species Specific

The European bison is a non-model organism; thus, most of its genetic and genomic analyses have been performed using cattle-specific resources, such as BovineSNP50 BeadChip or Illumina Bovine 800 K HD Bead Chip. The problem with non-specific tools is the potential loss of evolutionary diversified information (ascertainment bias) and species-specific markers. Here, we have used a genotyping-by-sequencing (GBS) approach for genotyping 256 samples from the European bison population in Bialowieza Forest (Poland) and performed an analysis using two integrated pipelines of the STACKS software: one is de novo (without reference genome) and the other is a reference pipeline (with reference genome). Moreover, we used a reference pipeline with two different genomes, i.e., Bos taurus and European bison. Genotyping by sequencing (GBS) is a useful tool for SNP genotyping in non-model organisms due to its cost effectiveness. Our results support GBS with a reference pipeline without PCR duplicates as a powerful approach for studying the population structure and genotyping data of non-model organisms. We found more polymorphic markers in the reference pipeline in comparison to the de novo pipeline. The decreased number of SNPs from the de novo pipeline could be due to the extremely low level of heterozygosity in European bison. It has been confirmed that all the de novo/Bos taurus and Bos taurus reference pipeline obtained SNPs were unique and not included in 800 K BovineHD BeadChip.

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Alliance of Genome Resources Portal: unified model organism research platform

Nucleic Acids Research ◽

10.1093/nar/gkz813 ◽

2019 ◽

Vol 48 (D1) ◽

pp. D650-D658 ◽

Cited By ~ 36

Author(s):

◽

Julie Agapite ◽

Laurent-Philippe Albou ◽

Suzi Aleksander ◽

Joanna Argasinska ◽

...

Keyword(s):

Gene Ontology ◽

Model Organism ◽

Model Organisms ◽

Data Types ◽

Primary Model ◽

Genomic Studies ◽

Health And Disease ◽

Extensive Body ◽

Access To Data ◽

Model Organism Databases

Abstract The Alliance of Genome Resources (Alliance) is a consortium of the major model organism databases and the Gene Ontology that is guided by the vision of facilitating exploration of related genes in human and well-studied model organisms by providing a highly integrated and comprehensive platform that enables researchers to leverage the extensive body of genetic and genomic studies in these organisms. Initiated in 2016, the Alliance is building a central portal (www.alliancegenome.org) for access to data for the primary model organisms along with gene ontology data and human data. All data types represented in the Alliance portal (e.g. genomic data and phenotype descriptions) have common data models and workflows for curation. All data are open and freely available via a variety of mechanisms. Long-term plans for the Alliance project include a focus on coverage of additional model organisms including those without dedicated curation communities, and the inclusion of new data types with a particular focus on providing data and tools for the non-model-organism researcher that support enhanced discovery about human health and disease. Here we review current progress and present immediate plans for this new bioinformatics resource.

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Insights into mammalian biology from the wild house mouse Mus musculus

eLife ◽

10.7554/elife.05959 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 45

Author(s):

Megan Phifer-Rixey ◽

Michael W Nachman

Keyword(s):

House Mouse ◽

Mus Musculus ◽

Genetic Model ◽

Inbred Strains ◽

Mendelian Inheritance ◽

Model Organisms ◽

House Mice ◽

Small Subset ◽

Wild Mice ◽

Wide Range

The house mouse, Mus musculus, was established in the early 1900s as one of the first genetic model organisms owing to its short generation time, comparatively large litters, ease of husbandry, and visible phenotypic variants. For these reasons and because they are mammals, house mice are well suited to serve as models for human phenotypes and disease. House mice in the wild consist of at least three distinct subspecies and harbor extensive genetic and phenotypic variation both within and between these subspecies. Wild mice have been used to study a wide range of biological processes, including immunity, cancer, male sterility, adaptive evolution, and non-Mendelian inheritance. Despite the extensive variation that exists among wild mice, classical laboratory strains are derived from a limited set of founders and thus contain only a small subset of this variation. Continued efforts to study wild house mice and to create new inbred strains from wild populations have the potential to strengthen house mice as a model system.

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