201
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Abstract
The ability to image and manipulate specific cell populations in Drosophila enables the investigation of how neural circuits develop and coordinate appropriate motor behaviors. Gal4 lines give genetic access to many types of neurons, but the expression patterns of these reagents are often complex. Here, we present the generation and expression patterns of LexA lines based on the vesicular neurotransmitter transporters and Hox transcription factors. Intersections between these LexA lines and existing Gal4 collections provide a strategy for rationally subdividing complex expression patterns based on neurotransmitter or segmental identity.
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Affiliation(s)
- J H Simpson
- a Janelia Research Campus , Howard Hughes Medical Institute , Ashburn , VA , USA.,b Molecular, Cellular and Developmental Biology Department , University of California, Santa Barbara , Santa Barbara , CA , USA
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202
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Sizemore TR, Dacks AM. Serotonergic Modulation Differentially Targets Distinct Network Elements within the Antennal Lobe of Drosophila melanogaster. Sci Rep 2016; 6:37119. [PMID: 27845422 PMCID: PMC5109230 DOI: 10.1038/srep37119] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/25/2016] [Indexed: 01/10/2023] Open
Abstract
Neuromodulation confers flexibility to anatomically-restricted neural networks so that animals are able to properly respond to complex internal and external demands. However, determining the mechanisms underlying neuromodulation is challenging without knowledge of the functional class and spatial organization of neurons that express individual neuromodulatory receptors. Here, we describe the number and functional identities of neurons in the antennal lobe of Drosophila melanogaster that express each of the receptors for one such neuromodulator, serotonin (5-HT). Although 5-HT enhances odor-evoked responses of antennal lobe projection neurons (PNs) and local interneurons (LNs), the receptor basis for this enhancement is unknown. We used endogenous reporters of transcription and translation for each of the five 5-HT receptors (5-HTRs) to identify neurons, based on cell class and transmitter content, that express each receptor. We find that specific receptor types are expressed by distinct combinations of functional neuronal classes. For instance, the excitatory PNs express the excitatory 5-HTRs, while distinct classes of LNs each express different 5-HTRs. This study therefore provides a detailed atlas of 5-HT receptor expression within a well-characterized neural network, and enables future dissection of the role of serotonergic modulation of olfactory processing.
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Affiliation(s)
- Tyler R Sizemore
- Department of Biology, West Virginia University, Morgantown, WV, 26505, United States of America
| | - Andrew M Dacks
- Department of Biology, West Virginia University, Morgantown, WV, 26505, United States of America
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203
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Riabinina O, Task D, Marr E, Lin CC, Alford R, O'Brochta DA, Potter CJ. Organization of olfactory centres in the malaria mosquito Anopheles gambiae. Nat Commun 2016; 7:13010. [PMID: 27694947 PMCID: PMC5063964 DOI: 10.1038/ncomms13010] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/25/2016] [Indexed: 02/01/2023] Open
Abstract
Mosquitoes are vectors for multiple infectious human diseases and use a variety of sensory cues (olfactory, temperature, humidity and visual) to locate a human host. A comprehensive understanding of the circuitry underlying sensory signalling in the mosquito brain is lacking. Here we used the Q-system of binary gene expression to develop transgenic lines of Anopheles gambiae in which olfactory receptor neurons expressing the odorant receptor co-receptor (Orco) gene are labelled with GFP. These neurons project from the antennae and maxillary palps to the antennal lobe (AL) and from the labella on the proboscis to the suboesophageal zone (SEZ), suggesting integration of olfactory and gustatory signals occurs in this brain region. We present detailed anatomical maps of olfactory innervations in the AL and the SEZ, identifying glomeruli that may respond to human body odours or carbon dioxide. Our results pave the way for anatomical and functional neurogenetic studies of sensory processing in mosquitoes.
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Affiliation(s)
- Olena Riabinina
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Darya Task
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Elizabeth Marr
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Chun-Chieh Lin
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Robert Alford
- University of Maryland College Park, 9600 Gudelsky Drive, Rockville, Maryland 20850, USA
| | - David A O'Brochta
- University of Maryland College Park, 9600 Gudelsky Drive, Rockville, Maryland 20850, USA
| | - Christopher J Potter
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
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204
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Ren Q, Awasaki T, Huang YF, Liu Z, Lee T. Cell Class-Lineage Analysis Reveals Sexually Dimorphic Lineage Compositions in the Drosophila Brain. Curr Biol 2016; 26:2583-2593. [PMID: 27618265 DOI: 10.1016/j.cub.2016.07.086] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 07/27/2016] [Accepted: 07/29/2016] [Indexed: 12/16/2022]
Abstract
The morphology and physiology of neurons are directed by developmental decisions made within their lines of descent from single stem cells. Distinct stem cells may produce neurons having shared properties that define their cell class, such as the type of secreted neurotransmitter. The relationship between cell class and lineage is complex. Here we developed the transgenic cell class-lineage intersection (CLIn) system to assign cells of a particular class to specific lineages within the Drosophila brain. CLIn also enables birth-order analysis and genetic manipulation of particular cell classes arising from particular lineages. We demonstrated the power of CLIn in the context of the eight central brain type II lineages, which produce highly diverse progeny through intermediate neural progenitors. We mapped 18 dopaminergic neurons from three distinct clusters to six type II lineages that show lineage-characteristic neurite trajectories. In addition, morphologically distinct dopaminergic neurons are produced within a given lineage, and they arise in an invariant sequence. We also identified type II lineages that produce doublesex- and fruitless-expressing neurons and examined whether female-specific apoptosis in these lineages accounts for the lower number of these neurons in the female brain. Blocking apoptosis in these lineages resulted in more cells in both sexes with males still carrying more cells than females. This argues that sex-specific stem cell fate together with differential progeny apoptosis contribute to the final sexual dimorphism.
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Affiliation(s)
- Qingzhong Ren
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Takeshi Awasaki
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Yu-Fen Huang
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Zhiyong Liu
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Tzumin Lee
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA.
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205
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Lin CC, Riabinina O, Potter CJ. Olfactory Behaviors Assayed by Computer Tracking Of Drosophila in a Four-quadrant Olfactometer. J Vis Exp 2016. [PMID: 27585032 DOI: 10.3791/54346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
A key challenge in neurobiology is to understand how neural circuits function to guide appropriate animal behaviors. Drosophila melanogaster is an excellent model system for such investigations due to its complex behaviors, powerful genetic techniques, and compact nervous system. Laboratory behavioral assays have long been used with Drosophila to simulate properties of the natural environment and study the neural mechanisms underlying the corresponding behaviors (e.g. phototaxis, chemotaxis, sensory learning and memory)(1-3). With the recent availability of large collections of transgenic Drosophila lines that label specific neural subsets, behavioral assays have taken on a prominent role to link neurons with behaviors(4-11). Versatile and reproducible paradigms, together with the underlying computational routines for data analysis, are indispensable for rapid tests of candidate fly lines with various genotypes. Particularly useful are setups that are flexible in the number of animals tested, duration of experiments and nature of presented stimuli. The assay of choice should also generate reproducible data that is easy to acquire and analyze. Here, we present a detailed description of a system and protocol for assaying behavioral responses of Drosophila flies in a large four-field arena. The setup is used here to assay responses of flies to a single olfactory stimulus; however, the same setup may be modified to test multiple olfactory, visual or optogenetic stimuli, or a combination of these. The olfactometer setup records the activity of fly populations responding to odors, and computational analytical methods are applied to quantify fly behaviors. The collected data are analyzed to get a quick read-out of an experimental run, which is essential for efficient data collection and the optimization of experimental conditions.
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Affiliation(s)
- Chun-Chieh Lin
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine
| | | | - Christopher J Potter
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine;
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206
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Lin CC, Potter CJ. Editing Transgenic DNA Components by Inducible Gene Replacement in Drosophila melanogaster. Genetics 2016; 203:1613-28. [PMID: 27334272 PMCID: PMC4981265 DOI: 10.1534/genetics.116.191783] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 06/07/2016] [Indexed: 11/18/2022] Open
Abstract
Gene conversions occur when genomic double-strand DNA breaks (DSBs) trigger unidirectional transfer of genetic material from a homologous template sequence. Exogenous or mutated sequence can be introduced through this homology-directed repair (HDR). We leveraged gene conversion to develop a method for genomic editing of existing transgenic insertions in Drosophila melanogaster The clustered regularly-interspaced palindromic repeats (CRISPR)/Cas9 system is used in the H: omology A: ssisted C: RISPR K: nock-in (HACK) method to induce DSBs in a GAL4 transgene, which is repaired by a single-genomic transgenic construct containing GAL4 homologous sequences flanking a T2A-QF2 cassette. With two crosses, this technique converts existing GAL4 lines, including enhancer traps, into functional QF2 expressing lines. We used HACK to convert the most commonly-used GAL4 lines (labeling tissues such as neurons, fat, glia, muscle, and hemocytes) to QF2 lines. We also identified regions of the genome that exhibited differential efficiencies of HDR. The HACK technique is robust and readily adaptable for targeting and replacement of other genomic sequences, and could be a useful approach to repurpose existing transgenes as new genetic reagents become available.
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Affiliation(s)
- Chun-Chieh Lin
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Christopher J Potter
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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207
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Guo F, Yu J, Jung HJ, Abruzzi KC, Luo W, Griffith LC, Rosbash M. Circadian neuron feedback controls the Drosophila sleep--activity profile. Nature 2016; 536:292-7. [PMID: 27479324 PMCID: PMC5247284 DOI: 10.1038/nature19097] [Citation(s) in RCA: 189] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 07/12/2016] [Indexed: 02/06/2023]
Abstract
Little is known about the ability of Drosophila circadian neurons to promote sleep. Here we show, using optogenetic manipulation and video recording, that a subset of dorsal clock neurons (DN1s) are potent sleep-promoting cells that release glutamate to directly inhibit key pacemaker neurons. The pacemakers promote morning arousal by activating these DN1s, implying that a late-day feedback circuit drives midday siesta and night-time sleep. To investigate more plastic aspects of the sleep program, we used a calcium assay to monitor and compare the real-time activity of DN1 neurons in freely behaving males and females. Our results revealed that DN1 neurons were more active in males than in females, consistent with the finding that male flies sleep more during the day. DN1 activity is also enhanced by elevated temperature, consistent with the ability of higher temperatures to increase sleep. These new approaches indicate that DN1s have a major effect on the fly sleep-wake profile and integrate environmental information with the circadian molecular program.
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208
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Owald D, Lin S, Waddell S. Light, heat, action: neural control of fruit fly behaviour. Philos Trans R Soc Lond B Biol Sci 2016; 370:20140211. [PMID: 26240426 PMCID: PMC4528823 DOI: 10.1098/rstb.2014.0211] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The fruit fly Drosophila melanogaster has emerged as a popular model to investigate fundamental principles of neural circuit operation. The sophisticated genetics and small brain permit a cellular resolution understanding of innate and learned behavioural processes. Relatively recent genetic and technical advances provide the means to specifically and reproducibly manipulate the function of many fly neurons with temporal resolution. The same cellular precision can also be exploited to express genetically encoded reporters of neural activity and cell-signalling pathways. Combining these approaches in living behaving animals has great potential to generate a holistic view of behavioural control that transcends the usual molecular, cellular and systems boundaries. In this review, we discuss these approaches with particular emphasis on the pioneering studies and those involving learning and memory.
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Affiliation(s)
- David Owald
- Centre for Neural Circuits and Behaviour, University of Oxford, Tinsley Building, Mansfield Road, Oxford OX1 3SR, UK
| | - Suewei Lin
- Centre for Neural Circuits and Behaviour, University of Oxford, Tinsley Building, Mansfield Road, Oxford OX1 3SR, UK
| | - Scott Waddell
- Centre for Neural Circuits and Behaviour, University of Oxford, Tinsley Building, Mansfield Road, Oxford OX1 3SR, UK
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209
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Abstract
Binary expression systems are flexible and versatile genetic tools in Drosophila. The Q-system is a recently developed repressible binary expression system that offers new possibilities for transgene expression and genetic manipulations. In this review chapter, we focus on current state-of-the-art Q-system tools and reagents. We also discuss in vivo applications of the Q-system, together with GAL4/UAS and LexA/LexAop systems, for simultaneous expression of multiple effectors, intersectional labeling, and clonal analysis.
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210
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Diao F, Mena W, Shi J, Park D, Diao F, Taghert P, Ewer J, White BH. The Splice Isoforms of the Drosophila Ecdysis Triggering Hormone Receptor Have Developmentally Distinct Roles. Genetics 2016; 202:175-89. [PMID: 26534952 PMCID: PMC4701084 DOI: 10.1534/genetics.115.182121] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/27/2015] [Indexed: 11/18/2022] Open
Abstract
To grow, insects must periodically shed their exoskeletons. This process, called ecdysis, is initiated by the endocrine release of Ecdysis Trigger Hormone (ETH) and has been extensively studied as a model for understanding the hormonal control of behavior. Understanding how ETH regulates ecdysis behavior, however, has been impeded by limited knowledge of the hormone's neuronal targets. An alternatively spliced gene encoding a G-protein-coupled receptor (ETHR) that is activated by ETH has been identified, and several lines of evidence support a role in ecdysis for its A-isoform. The function of a second ETHR isoform (ETHRB) remains unknown. Here we use the recently introduced "Trojan exon" technique to simultaneously mutate the ETHR gene and gain genetic access to the neurons that express its two isoforms. We show that ETHRA and ETHRB are expressed in largely distinct subsets of neurons and that ETHRA- but not ETHRB-expressing neurons are required for ecdysis at all developmental stages. However, both genetic and neuronal manipulations indicate an essential role for ETHRB at pupal and adult, but not larval, ecdysis. We also identify several functionally important subsets of ETHR-expressing neurons including one that coexpresses the peptide Leucokinin and regulates fluid balance to facilitate ecdysis at the pupal stage. The general strategy presented here of using a receptor gene as an entry point for genetic and neuronal manipulations should be useful in establishing patterns of functional connectivity in other hormonally regulated networks.
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Affiliation(s)
- Feici Diao
- Laboratory of Molecular Biology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
| | - Wilson Mena
- Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Playa Ancha, Valparaiso, Chile
| | - Jonathan Shi
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, Missouri 63110
| | - Dongkook Park
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, Missouri 63110
| | - Fengqiu Diao
- Laboratory of Molecular Biology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
| | - Paul Taghert
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, Missouri 63110
| | - John Ewer
- Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Playa Ancha, Valparaiso, Chile
| | - Benjamin H White
- Laboratory of Molecular Biology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892
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211
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Abstract
Fluorescent protein tags have revolutionized cell and developmental biology, and in combination with binary expression systems they enable diverse tissue-specific studies of protein function. However these binary expression systems often do not recapitulate endogenous protein expression levels, localization, binding partners and/or developmental windows of gene expression. To address these limitations, we have developed a method called T-STEP (tissue-specific tagging of endogenous proteins) that allows endogenous loci to be tagged in a tissue specific manner. T-STEP uses a combination of efficient CRISPR/Cas9-enhanced gene targeting and tissue-specific recombinase-mediated tag swapping to temporally and spatially label endogenous proteins. We have employed this method to GFP tag OCRL (a phosphoinositide-5-phosphatase in the endocytic pathway) and Vps35 (a Parkinson's disease-implicated component of the endosomal retromer complex) in diverse Drosophila tissues including neurons, glia, muscles and hemocytes. Selective tagging of endogenous proteins allows, for the first time, cell type-specific live imaging and proteomics in complex tissues.
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Affiliation(s)
- Kate Koles
- Department of Biology, Brandeis University, 415 South St, Waltham, MA 02454, USA
| | - Anna R Yeh
- Department of Biology, Brandeis University, 415 South St, Waltham, MA 02454, USA
| | - Avital A Rodal
- Department of Biology, Brandeis University, 415 South St, Waltham, MA 02454, USA
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212
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Abstract
In 1915, "The Mechanism of Mendelian Heredity" was published by four prominent Drosophila geneticists. They discovered that genes form linkage groups on chromosomes inherited in a Mendelian fashion and laid the genetic foundation that promoted Drosophila as a model organism. Flies continue to offer great opportunities, including studies in the field of functional genomics.
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Affiliation(s)
- Hugo J Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Howard Hughes Medical Institute (HHMI), Houston, TX, 77030, USA.
| | - Shinya Yamamoto
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
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213
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Kallman BR, Kim H, Scott K. Excitation and inhibition onto central courtship neurons biases Drosophila mate choice. eLife 2015; 4:e11188. [PMID: 26568316 PMCID: PMC4695383 DOI: 10.7554/elife.11188] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 11/12/2015] [Indexed: 01/05/2023] Open
Abstract
The ability to distinguish males from females is essential for productive mate selection and species propagation. Recent studies in Drosophila have identified different classes of contact chemosensory neurons that detect female or male pheromones and influence courtship decisions. Here, we examine central neural pathways in the male brain that process female and male pheromones using anatomical, calcium imaging, optogenetic, and behavioral studies. We find that sensory neurons that detect female pheromones, but not male pheromones, activate a novel class of neurons in the ventral nerve cord to cause activation of P1 neurons, male-specific command neurons that trigger courtship. In addition, sensory neurons that detect male pheromones, as well as those that detect female pheromones, activate central mAL neurons to inhibit P1. These studies demonstrate that the balance of excitatory and inhibitory drives onto central courtship-promoting neurons controls mating decisions.
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Affiliation(s)
- Benjamin R Kallman
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, United States
| | - Heesoo Kim
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, United States
| | - Kristin Scott
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, United States
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214
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Venken KJT, Sarrion-Perdigones A, Vandeventer PJ, Abel NS, Christiansen AE, Hoffman KL. Genome engineering: Drosophila melanogaster and beyond. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 5:233-67. [PMID: 26447401 DOI: 10.1002/wdev.214] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 08/03/2015] [Accepted: 08/20/2015] [Indexed: 12/26/2022]
Abstract
A central challenge in investigating biological phenomena is the development of techniques to modify genomic DNA with nucleotide precision that can be transmitted through the germ line. Recent years have brought a boon in these technologies, now collectively known as genome engineering. Defined genomic manipulations at the nucleotide level enable a variety of reverse engineering paradigms, providing new opportunities to interrogate diverse biological functions. These genetic modifications include controlled removal, insertion, and substitution of genetic fragments, both small and large. Small fragments up to a few kilobases (e.g., single nucleotide mutations, small deletions, or gene tagging at single or multiple gene loci) to large fragments up to megabase resolution can be manipulated at single loci to create deletions, duplications, inversions, or translocations of substantial sections of whole chromosome arms. A specialized substitution of chromosomal portions that presumably are functionally orthologous between different organisms through syntenic replacement, can provide proof of evolutionary conservation between regulatory sequences. Large transgenes containing endogenous or synthetic DNA can be integrated at defined genomic locations, permitting an alternative proof of evolutionary conservation, and sophisticated transgenes can be used to interrogate biological phenomena. Precision engineering can additionally be used to manipulate the genomes of organelles (e.g., mitochondria). Novel genome engineering paradigms are often accelerated in existing, easily genetically tractable model organisms, primarily because these paradigms can be integrated in a rigorous, existing technology foundation. The Drosophila melanogaster fly model is ideal for these types of studies. Due to its small genome size, having just four chromosomes, the vast amount of cutting-edge genetic technologies, and its short life-cycle and inexpensive maintenance requirements, the fly is exceptionally amenable to complex genetic analysis using advanced genome engineering. Thus, highly sophisticated methods developed in the fly model can be used in nearly any sequenced organism. Here, we summarize different ways to perform precise inheritable genome engineering using integrases, recombinases, and DNA nucleases in the D. melanogaster. For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Koen J T Venken
- Department of Biochemistry and Molecular Biology, Verna and Marrs McLean, Houston, TX, USA.,Department of Pharmacology, Baylor College of Medicine, Houston, TX, USA.,Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA.,Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX, USA
| | | | - Paul J Vandeventer
- Department of Biochemistry and Molecular Biology, Verna and Marrs McLean, Houston, TX, USA
| | - Nicholas S Abel
- Department of Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Audrey E Christiansen
- Department of Biochemistry and Molecular Biology, Verna and Marrs McLean, Houston, TX, USA
| | - Kristi L Hoffman
- Department of Biochemistry and Molecular Biology, Verna and Marrs McLean, Houston, TX, USA
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215
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Krüger E, Mena W, Lahr EC, Johnson EC, Ewer J. Genetic analysis of Eclosion hormone action during Drosophila larval ecdysis. Development 2015; 142:4279-87. [PMID: 26395475 DOI: 10.1242/dev.126995] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 09/07/2015] [Indexed: 11/20/2022]
Abstract
Insect growth is punctuated by molts, during which the animal produces a new exoskeleton. The molt culminates in ecdysis, an ordered sequence of behaviors that causes the old cuticle to be shed. This sequence is activated by Ecdysis triggering hormone (ETH), which acts on the CNS to activate neurons that produce neuropeptides implicated in ecdysis, including Eclosion hormone (EH), Crustacean cardioactive peptide (CCAP) and Bursicon. Despite more than 40 years of research on ecdysis, our understanding of the precise roles of these neurohormones remains rudimentary. Of particular interest is EH; although it is known to upregulate ETH release, other roles for EH have remained elusive. We isolated an Eh null mutant in Drosophila and used it to investigate the role of EH in larval ecdysis. We found that null mutant animals invariably died at around the time of ecdysis, revealing an essential role in its control. Further analyses showed that these animals failed to express the preparatory behavior of pre-ecdysis while directly expressing the motor program of ecdysis. Although ETH release could not be detected, the lack of pre-ecdysis could not be rescued by injections of ETH, suggesting that EH is required within the CNS for ETH to trigger the normal ecdysial sequence. Using a genetically encoded calcium probe, we showed that EH configured the response of the CNS to ETH. These findings show that EH plays an essential role in the Drosophila CNS in the control of ecdysis, in addition to its known role in the periphery of triggering ETH release.
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Affiliation(s)
- Eileen Krüger
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2360102, Chile
| | - Wilson Mena
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2360102, Chile
| | - Eleanor C Lahr
- Entomology Department, Cornell University, 5130 Comstock, Ithaca, NY 14850, USA Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77840, USA
| | - Erik C Johnson
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA
| | - John Ewer
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2360102, Chile Entomology Department, Cornell University, 5130 Comstock, Ithaca, NY 14850, USA
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216
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Nagarkar-Jaiswal S, DeLuca SZ, Lee PT, Lin WW, Pan H, Zuo Z, Lv J, Spradling AC, Bellen HJ. A genetic toolkit for tagging intronic MiMIC containing genes. eLife 2015; 4. [PMID: 26102525 PMCID: PMC4499919 DOI: 10.7554/elife.08469] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 06/22/2015] [Indexed: 12/20/2022] Open
Abstract
Previously, we described a large collection of Minos-Mediated Integration Cassettes (MiMICs) that contain two phiC31 recombinase target sites and allow the generation of a new exon that encodes a protein tag when the MiMIC is inserted in a codon intron (Nagarkar-Jaiswal et al., 2015). These modified genes permit numerous applications including assessment of protein expression pattern, identification of protein interaction partners by immunoprecipitation followed by mass spec, and reversible removal of the tagged protein in any tissue. At present, these conversions remain time and labor-intensive as they require embryos to be injected with plasmid DNA containing the exon tag. In this study, we describe a simple and reliable genetic strategy to tag genes/proteins that contain MiMIC insertions using an integrated exon encoding GFP flanked by FRT sequences. We document the efficiency and tag 60 mostly uncharacterized genes.
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Affiliation(s)
| | - Steven Z DeLuca
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Wen-Wen Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Hongling Pan
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Jiangxing Lv
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Hugo J Bellen
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
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Langenhan T, Barr MM, Bruchas MR, Ewer J, Griffith LC, Maiellaro I, Taghert PH, White BH, Monk KR. Model Organisms in G Protein-Coupled Receptor Research. Mol Pharmacol 2015; 88:596-603. [PMID: 25979002 DOI: 10.1124/mol.115.098764] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 05/14/2015] [Indexed: 12/19/2022] Open
Abstract
The study of G protein-coupled receptors (GPCRs) has benefited greatly from experimental approaches that interrogate their functions in controlled, artificial environments. Working in vitro, GPCR receptorologists discovered the basic biologic mechanisms by which GPCRs operate, including their eponymous capacity to couple to G proteins; their molecular makeup, including the famed serpentine transmembrane unit; and ultimately, their three-dimensional structure. Although the insights gained from working outside the native environments of GPCRs have allowed for the collection of low-noise data, such approaches cannot directly address a receptor's native (in vivo) functions. An in vivo approach can complement the rigor of in vitro approaches: as studied in model organisms, it imposes physiologic constraints on receptor action and thus allows investigators to deduce the most salient features of receptor function. Here, we briefly discuss specific examples in which model organisms have successfully contributed to the elucidation of signals controlled through GPCRs and other surface receptor systems. We list recent examples that have served either in the initial discovery of GPCR signaling concepts or in their fuller definition. Furthermore, we selectively highlight experimental advantages, shortcomings, and tools of each model organism.
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Affiliation(s)
- Tobias Langenhan
- Institute of Physiology, Department of Neurophysiology (T.L.), and Institute of Pharmacology and Toxicology, Rudolf Virchow Center (I.M.), University of Würzburg, Germany, Würzburg, Germany; Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey (M.M.B.); Division of Basic Research, Department of Anesthesiology, Washington University Pain Center (M.R.B.), Division of Biological and Biomedical Sciences, Department of Anatomy and Neurobiology (M.R.B., P.H.T.), and Department of Developmental Biology, Hope Center for Neurologic Disorders, (K.R.M.), Washington University School of Medicine, St. Louis, Missouri; Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Valparaiso, Chile (J.E.); National Center of Behavioral Genomics, Volen Center for Complex Systems, and Department of Biology, Brandeis University, Waltham, Massachusetts (L.C.G.); and Laboratory of Molecular Biology, National Institutes of Health National Institute of Mental Health, Bethesda, Maryland (B.H.W.)
| | - Maureen M Barr
- Institute of Physiology, Department of Neurophysiology (T.L.), and Institute of Pharmacology and Toxicology, Rudolf Virchow Center (I.M.), University of Würzburg, Germany, Würzburg, Germany; Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey (M.M.B.); Division of Basic Research, Department of Anesthesiology, Washington University Pain Center (M.R.B.), Division of Biological and Biomedical Sciences, Department of Anatomy and Neurobiology (M.R.B., P.H.T.), and Department of Developmental Biology, Hope Center for Neurologic Disorders, (K.R.M.), Washington University School of Medicine, St. Louis, Missouri; Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Valparaiso, Chile (J.E.); National Center of Behavioral Genomics, Volen Center for Complex Systems, and Department of Biology, Brandeis University, Waltham, Massachusetts (L.C.G.); and Laboratory of Molecular Biology, National Institutes of Health National Institute of Mental Health, Bethesda, Maryland (B.H.W.)
| | - Michael R Bruchas
- Institute of Physiology, Department of Neurophysiology (T.L.), and Institute of Pharmacology and Toxicology, Rudolf Virchow Center (I.M.), University of Würzburg, Germany, Würzburg, Germany; Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey (M.M.B.); Division of Basic Research, Department of Anesthesiology, Washington University Pain Center (M.R.B.), Division of Biological and Biomedical Sciences, Department of Anatomy and Neurobiology (M.R.B., P.H.T.), and Department of Developmental Biology, Hope Center for Neurologic Disorders, (K.R.M.), Washington University School of Medicine, St. Louis, Missouri; Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Valparaiso, Chile (J.E.); National Center of Behavioral Genomics, Volen Center for Complex Systems, and Department of Biology, Brandeis University, Waltham, Massachusetts (L.C.G.); and Laboratory of Molecular Biology, National Institutes of Health National Institute of Mental Health, Bethesda, Maryland (B.H.W.)
| | - John Ewer
- Institute of Physiology, Department of Neurophysiology (T.L.), and Institute of Pharmacology and Toxicology, Rudolf Virchow Center (I.M.), University of Würzburg, Germany, Würzburg, Germany; Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey (M.M.B.); Division of Basic Research, Department of Anesthesiology, Washington University Pain Center (M.R.B.), Division of Biological and Biomedical Sciences, Department of Anatomy and Neurobiology (M.R.B., P.H.T.), and Department of Developmental Biology, Hope Center for Neurologic Disorders, (K.R.M.), Washington University School of Medicine, St. Louis, Missouri; Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Valparaiso, Chile (J.E.); National Center of Behavioral Genomics, Volen Center for Complex Systems, and Department of Biology, Brandeis University, Waltham, Massachusetts (L.C.G.); and Laboratory of Molecular Biology, National Institutes of Health National Institute of Mental Health, Bethesda, Maryland (B.H.W.)
| | - Leslie C Griffith
- Institute of Physiology, Department of Neurophysiology (T.L.), and Institute of Pharmacology and Toxicology, Rudolf Virchow Center (I.M.), University of Würzburg, Germany, Würzburg, Germany; Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey (M.M.B.); Division of Basic Research, Department of Anesthesiology, Washington University Pain Center (M.R.B.), Division of Biological and Biomedical Sciences, Department of Anatomy and Neurobiology (M.R.B., P.H.T.), and Department of Developmental Biology, Hope Center for Neurologic Disorders, (K.R.M.), Washington University School of Medicine, St. Louis, Missouri; Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Valparaiso, Chile (J.E.); National Center of Behavioral Genomics, Volen Center for Complex Systems, and Department of Biology, Brandeis University, Waltham, Massachusetts (L.C.G.); and Laboratory of Molecular Biology, National Institutes of Health National Institute of Mental Health, Bethesda, Maryland (B.H.W.)
| | - Isabella Maiellaro
- Institute of Physiology, Department of Neurophysiology (T.L.), and Institute of Pharmacology and Toxicology, Rudolf Virchow Center (I.M.), University of Würzburg, Germany, Würzburg, Germany; Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey (M.M.B.); Division of Basic Research, Department of Anesthesiology, Washington University Pain Center (M.R.B.), Division of Biological and Biomedical Sciences, Department of Anatomy and Neurobiology (M.R.B., P.H.T.), and Department of Developmental Biology, Hope Center for Neurologic Disorders, (K.R.M.), Washington University School of Medicine, St. Louis, Missouri; Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Valparaiso, Chile (J.E.); National Center of Behavioral Genomics, Volen Center for Complex Systems, and Department of Biology, Brandeis University, Waltham, Massachusetts (L.C.G.); and Laboratory of Molecular Biology, National Institutes of Health National Institute of Mental Health, Bethesda, Maryland (B.H.W.)
| | - Paul H Taghert
- Institute of Physiology, Department of Neurophysiology (T.L.), and Institute of Pharmacology and Toxicology, Rudolf Virchow Center (I.M.), University of Würzburg, Germany, Würzburg, Germany; Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey (M.M.B.); Division of Basic Research, Department of Anesthesiology, Washington University Pain Center (M.R.B.), Division of Biological and Biomedical Sciences, Department of Anatomy and Neurobiology (M.R.B., P.H.T.), and Department of Developmental Biology, Hope Center for Neurologic Disorders, (K.R.M.), Washington University School of Medicine, St. Louis, Missouri; Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Valparaiso, Chile (J.E.); National Center of Behavioral Genomics, Volen Center for Complex Systems, and Department of Biology, Brandeis University, Waltham, Massachusetts (L.C.G.); and Laboratory of Molecular Biology, National Institutes of Health National Institute of Mental Health, Bethesda, Maryland (B.H.W.)
| | - Benjamin H White
- Institute of Physiology, Department of Neurophysiology (T.L.), and Institute of Pharmacology and Toxicology, Rudolf Virchow Center (I.M.), University of Würzburg, Germany, Würzburg, Germany; Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey (M.M.B.); Division of Basic Research, Department of Anesthesiology, Washington University Pain Center (M.R.B.), Division of Biological and Biomedical Sciences, Department of Anatomy and Neurobiology (M.R.B., P.H.T.), and Department of Developmental Biology, Hope Center for Neurologic Disorders, (K.R.M.), Washington University School of Medicine, St. Louis, Missouri; Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Valparaiso, Chile (J.E.); National Center of Behavioral Genomics, Volen Center for Complex Systems, and Department of Biology, Brandeis University, Waltham, Massachusetts (L.C.G.); and Laboratory of Molecular Biology, National Institutes of Health National Institute of Mental Health, Bethesda, Maryland (B.H.W.)
| | - Kelly R Monk
- Institute of Physiology, Department of Neurophysiology (T.L.), and Institute of Pharmacology and Toxicology, Rudolf Virchow Center (I.M.), University of Würzburg, Germany, Würzburg, Germany; Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, New Jersey (M.M.B.); Division of Basic Research, Department of Anesthesiology, Washington University Pain Center (M.R.B.), Division of Biological and Biomedical Sciences, Department of Anatomy and Neurobiology (M.R.B., P.H.T.), and Department of Developmental Biology, Hope Center for Neurologic Disorders, (K.R.M.), Washington University School of Medicine, St. Louis, Missouri; Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Valparaiso, Chile (J.E.); National Center of Behavioral Genomics, Volen Center for Complex Systems, and Department of Biology, Brandeis University, Waltham, Massachusetts (L.C.G.); and Laboratory of Molecular Biology, National Institutes of Health National Institute of Mental Health, Bethesda, Maryland (B.H.W.)
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Nagarkar-Jaiswal S, Lee PT, Campbell ME, Chen K, Anguiano-Zarate S, Gutierrez MC, Busby T, Lin WW, He Y, Schulze KL, Booth BW, Evans-Holm M, Venken KJT, Levis RW, Spradling AC, Hoskins RA, Bellen HJ. A library of MiMICs allows tagging of genes and reversible, spatial and temporal knockdown of proteins in Drosophila. eLife 2015; 4. [PMID: 25824290 PMCID: PMC4379497 DOI: 10.7554/elife.05338] [Citation(s) in RCA: 256] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Accepted: 02/06/2015] [Indexed: 01/19/2023] Open
Abstract
Here, we document a collection of ∼7434 MiMIC (Minos Mediated Integration Cassette) insertions of which 2854 are inserted in coding introns. They allowed us to create a library of 400 GFP-tagged genes. We show that 72% of internally tagged proteins are functional, and that more than 90% can be imaged in unfixed tissues. Moreover, the tagged mRNAs can be knocked down by RNAi against GFP (iGFPi), and the tagged proteins can be efficiently knocked down by deGradFP technology. The phenotypes associated with RNA and protein knockdown typically correspond to severe loss of function or null mutant phenotypes. Finally, we demonstrate reversible, spatial, and temporal knockdown of tagged proteins in larvae and adult flies. This new strategy and collection of strains allows unprecedented in vivo manipulations in flies for many genes. These strategies will likely extend to vertebrates. DOI:http://dx.doi.org/10.7554/eLife.05338.001 In the last few decades, technical advances in altering the genes of organisms have led to many discoveries about how genes work. For example, it is now possible to add a specific DNA sequence to a gene so that the protein it makes will carry a ‘tag’ that enables us to track it in cells. One such tag is called green fluorescent protein (GFP) and it is often used to study other proteins in living cells because it produces green fluorescence that can be detected under a microscope. It is labor intensive to add tags to individual genes, so this limits the number of proteins that can be studied in this way. In 2011, researchers developed a new method that can easily tag many genes in fruit flies. It makes use of small sections of DNA called transposons, which are able to move around the genome by ‘cutting’ themselves out of one location and ‘pasting’ themselves in somewhere else. The researchers used a transposon called Minos, which is naturally found in fruit flies. When Minos inserts into a gene, it often disrupts the gene and stops it from working. However, the researchers could swap the inserted transposon for a gene encoding GFP by making use of a natural process that rearranges DNA in cells. This resulted in the protein encoded by the gene containing GFP and so it can be detected under a microscope. This method allowed the researchers to create a collection of fly lines that have the GFP tag on many different proteins. Now, Nagarkar-Jaiswal et al. have greatly expanded this initial collection. More than 75% of GFP-tagged proteins worked normally and the flies producing these altered proteins remain healthy. It is possible to use a technique called RNA interference against the GFP to lower the production of the tagged proteins. Moreover, Nagarkar-Jaiswal et al. show that it is also possible to degrade the tagged proteins so that less protein is present. The removal of proteins is reversible and can be done in specific tissues during any phase in fly development. These techniques allow researchers to directly associate the loss of the protein with the consequences for the fly. This collection of fruit fly lines is a useful resource that can help us understand how genes work. The method for tagging the proteins could also be modified to work in other animals. DOI:http://dx.doi.org/10.7554/eLife.05338.002
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Affiliation(s)
- Sonal Nagarkar-Jaiswal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Megan E Campbell
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Kuchuan Chen
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | | | - Manuel Cantu Gutierrez
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Theodore Busby
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Wen-Wen Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Yuchun He
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Karen L Schulze
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Benjamin W Booth
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Martha Evans-Holm
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Koen J T Venken
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, United States
| | - Robert W Levis
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Roger A Hoskins
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
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219
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Gnerer JP, Venken KJT, Dierick HA. Gene-specific cell labeling using MiMIC transposons. Nucleic Acids Res 2015; 43:e56. [PMID: 25712101 PMCID: PMC4417149 DOI: 10.1093/nar/gkv113] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 02/03/2015] [Indexed: 12/30/2022] Open
Abstract
Binary expression systems such as GAL4/UAS, LexA/LexAop and QF/QUAS have greatly enhanced the power of Drosophila as a model organism by allowing spatio-temporal manipulation of gene function as well as cell and neural circuit function. Tissue-specific expression of these heterologous transcription factors relies on random transposon integration near enhancers or promoters that drive the binary transcription factor embedded in the transposon. Alternatively, gene-specific promoter elements are directly fused to the binary factor within the transposon followed by random or site-specific integration. However, such insertions do not consistently recapitulate endogenous expression. We used Minos-Mediated Integration Cassette (MiMIC) transposons to convert host loci into reliable gene-specific binary effectors. MiMIC transposons allow recombinase-mediated cassette exchange to modify the transposon content. We developed novel exchange cassettes to convert coding intronic MiMIC insertions into gene-specific binary factor protein-traps. In addition, we expanded the set of binary factor exchange cassettes available for non-coding intronic MiMIC insertions. We show that binary factor conversions of different insertions in the same locus have indistinguishable expression patterns, suggesting that they reliably reflect endogenous gene expression. We show the efficacy and broad applicability of these new tools by dissecting the cellular expression patterns of the Drosophila serotonin receptor gene family.
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Affiliation(s)
- Joshua P Gnerer
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Koen J T Venken
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA Dan L. Ducan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA Program in Integrative and Molecular Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Herman A Dierick
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
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