51
|
Wunderlich Z, Fowlkes CC, Eckenrode KB, Bragdon MDJ, Abiri A, DePace AH. Quantitative Comparison of the Anterior-Posterior Patterning System in the Embryos of Five Drosophila Species. G3 (BETHESDA, MD.) 2019; 9:2171-2182. [PMID: 31048401 PMCID: PMC6643877 DOI: 10.1534/g3.118.200953] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 05/01/2019] [Indexed: 11/18/2022]
Abstract
Complex spatiotemporal gene expression patterns direct the development of the fertilized egg into an adult animal. Comparisons across species show that, in spite of changes in the underlying regulatory DNA sequence, developmental programs can be maintained across millions of years of evolution. Reciprocally, changes in gene expression can be used to generate morphological novelty. Distinguishing between changes in regulatory DNA that lead to changes in gene expression and those that do not is therefore a central goal of evolutionary developmental biology. Quantitative, spatially-resolved measurements of developmental gene expression patterns play a crucial role in this goal, enabling the detection of subtle phenotypic differences between species and the development of computations models that link the sequence of regulatory DNA to expression patterns. Here we report the generation of two atlases of cellular resolution gene expression measurements for the primary anterior-posterior patterning genes in Drosophila simulans and Drosophila virilis By combining these data sets with existing atlases for three other Drosophila species, we detect subtle differences in the gene expression patterns and dynamics driving the highly conserved axis patterning system and delineate inter-species differences in the embryonic morphology. These data sets will be a resource for future modeling studies of the evolution of developmental gene regulatory networks.
Collapse
Affiliation(s)
- Zeba Wunderlich
- Department of Developmental and Cell Biology, University of California, Irvine, CA, 92697
| | - Charless C Fowlkes
- Department of Computer Science, University of California, Irvine, CA, 92697
| | - Kelly B Eckenrode
- Department of Systems Biology, Harvard Medical School, Boston, MA, 20115
| | - Meghan D J Bragdon
- Department of Systems Biology, Harvard Medical School, Boston, MA, 20115
| | - Arash Abiri
- Department of Developmental and Cell Biology, University of California, Irvine, CA, 92697
| | - Angela H DePace
- Department of Systems Biology, Harvard Medical School, Boston, MA, 20115
| |
Collapse
|
52
|
Lybrand DB, Naiman M, Laumann JM, Boardman M, Petshow S, Hansen K, Scott G, Wehrli M. Destruction complex dynamics: Wnt/β-catenin signaling alters Axin-GSK3β interactions in vivo. Development 2019; 146:dev164145. [PMID: 31189665 PMCID: PMC6633605 DOI: 10.1242/dev.164145] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 06/05/2019] [Indexed: 01/20/2023]
Abstract
The central regulator of the Wnt/β-catenin pathway is the Axin/APC/GSK3β destruction complex (DC), which, under unstimulated conditions, targets cytoplasmic β-catenin for degradation. How Wnt activation inhibits the DC to permit β-catenin-dependent signaling remains controversial, in part because the DC and its regulation have never been observed in vivo Using bimolecular fluorescence complementation (BiFC) methods, we have now analyzed the activity of the DC under near-physiological conditions in Drosophila By focusing on well-established patterns of Wnt/Wg signaling in the developing Drosophila wing, we have defined the sequence of events by which activated Wnt receptors induce a conformational change within the DC, resulting in modified Axin-GSK3β interactions that prevent β-catenin degradation. Surprisingly, the nucleus is surrounded by active DCs, which principally control the degradation of β-catenin and thereby nuclear access. These DCs are inactivated and removed upon Wnt signal transduction. These results suggest a novel mechanistic model for dynamic Wnt signal transduction in vivo.
Collapse
Affiliation(s)
- Daniel B Lybrand
- Dept. of Integrative Biosciences, School of Dentistry, Oregon Health and Science University, Portland, OR 97239, USA
- Reed College, Portland, OR 97202, USA
| | - Misha Naiman
- Dept. of Integrative Biosciences, School of Dentistry, Oregon Health and Science University, Portland, OR 97239, USA
- Reed College, Portland, OR 97202, USA
| | - Jessie May Laumann
- Dept. of Integrative Biosciences, School of Dentistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Mitzi Boardman
- Dept. of Integrative Biosciences, School of Dentistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Samuel Petshow
- Dept. of Integrative Biosciences, School of Dentistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Kevin Hansen
- Dept. of Integrative Biosciences, School of Dentistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Gregory Scott
- Dept. of Integrative Biosciences, School of Dentistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Marcel Wehrli
- Dept. of Integrative Biosciences, School of Dentistry, Oregon Health and Science University, Portland, OR 97239, USA
- Knight Cancer Institute, Portland, OR 97239, USA
| |
Collapse
|
53
|
Zhao J, Warman GR, Stanewsky R, Cheeseman JF. Development of the Molecular Circadian Clock and Its Light Sensitivity in Drosophila Melanogaster. J Biol Rhythms 2019; 34:272-282. [PMID: 30879378 DOI: 10.1177/0748730419836818] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The importance of the circadian clock for the control of behavior and physiology is well established but how and when it develops is not fully understood. Here the initial expression pattern of the key clock gene period was recorded in Drosophila from embryos in vivo, using transgenic luciferase reporters. PERIOD expression in the presumptive central-clock dorsal neurons started to oscillate in the embryo in constant darkness. In behavioral experiments, a single 12-h light pulse given during the embryonic stage synchronized adult activity rhythms, implying the early development of entrainment mechanisms. These findings suggest that the central clock is functional already during embryogenesis. In contrast to central brain expression, PERIOD in the peripheral cells or their precursors increased during the embryonic stage and peaked during the pupal stage without showing circadian oscillations. Its rhythmic expression only initiated in the adult. We conclude that cyclic expression of PERIOD in the central-clock neurons starts in the embryo, presumably in the dorsal neurons or their precursors. It is not until shortly after eclosion when cyclic and synchronized expression of PERIOD in peripheral tissues commences throughout the animal.
Collapse
Affiliation(s)
- Jia Zhao
- Department of Anaesthesiology, School of Medicine, University of Auckland, Auckland, 1142 New Zealand
| | - Guy Robert Warman
- Department of Anaesthesiology, School of Medicine, University of Auckland, Auckland, 1142 New Zealand
| | - Ralf Stanewsky
- Institute for Neuro- and Behavioral Biology, Westfälische Wilhelms University, 48149 Münster, Germany
| | - James Frederick Cheeseman
- Department of Anaesthesiology, School of Medicine, University of Auckland, Auckland, 1142 New Zealand
| |
Collapse
|
54
|
Ali S, Signor SA, Kozlov K, Nuzhdin SV. Novel approach to quantitative spatial gene expression uncovers genetic stochasticity in the developing Drosophila eye. Evol Dev 2019; 21:157-171. [PMID: 30756455 DOI: 10.1111/ede.12283] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Robustness in development allows for the accumulation of genetically based variation in expression. However, this variation is usually examined in response to large perturbations, and examination of this variation has been limited to being spatial, or quantitative, but because of technical restrictions not both. Here we bridge these gaps by investigating replicated quantitative spatial gene expression using rigorous statistical models, in different genotypes, sexes, and species (Drosophila melanogaster and D. simulans). Using this type of quantitative approach with molecular developmental data allows for comparison among conditions, such as different genetic backgrounds. We apply this approach to the morphogenetic furrow, a wave of differentiation that patterns the developing eye disc. Within the morphogenetic furrow, we focus on four genes, hairy, atonal, hedgehog, and Delta. Hybridization chain reaction quantitatively measures spatial gene expression, co-staining for all four genes simultaneously. We find considerable variation in the spatial expression pattern of these genes in the eye between species, genotypes, and sexes. We also find that there has been evolution of the regulatory relationship between these genes, and that their spatial interrelationships have evolved between species. This variation has no phenotypic effect, and could be buffered by network thresholds or compensation from other genes. Both of these mechanisms could potentially be contributing to long term developmental systems drift.
Collapse
Affiliation(s)
- Sammi Ali
- Molecular and Computational Biology, University of Southern California, Los Angeles, California
| | - Sarah A Signor
- Molecular and Computational Biology, University of Southern California, Los Angeles, California
| | - Konstantin Kozlov
- Department of Applied Mathematics, St. Petersburg State Polytechnic University, St. Petersburg, Russia
| | - Sergey V Nuzhdin
- Molecular and Computational Biology, University of Southern California, Los Angeles, California.,Department of Applied Mathematics, St. Petersburg State Polytechnic University, St. Petersburg, Russia
| |
Collapse
|
55
|
A Modular Millifluidic Homeostatic Imaging Plate for Imaging of Larval Zebrafish. Zebrafish 2019; 16:37-46. [DOI: 10.1089/zeb.2018.1684] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
|
56
|
Evolution of maternal and zygotic mRNA complements in the early Drosophila embryo. PLoS Genet 2018; 14:e1007838. [PMID: 30557299 PMCID: PMC6312346 DOI: 10.1371/journal.pgen.1007838] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Revised: 12/31/2018] [Accepted: 11/18/2018] [Indexed: 01/19/2023] Open
Abstract
The earliest stages of animal development are controlled by maternally deposited mRNA transcripts and proteins. Once the zygote is able to transcribe its own genome, maternal transcripts are degraded, in a tightly regulated process known as the maternal to zygotic transition (MZT). While this process has been well-studied within model species, we have little knowledge of how the pools of maternal and zygotic transcripts evolve. To characterize the evolutionary dynamics and functional constraints on early embryonic expression, we created a transcriptomic dataset for 14 Drosophila species spanning over 50 million years of evolution, at developmental stages before and after the MZT, and compared our results with a previously published Aedes aegypti developmental time course. We found deep conservation over 250 million years of a core set of genes transcribed only by the zygote. This select group is highly enriched in transcription factors that play critical roles in early development. However, we also identify a surprisingly high level of change in the transcripts represented at both stages over the phylogeny. While mRNA levels of genes with maternally deposited transcripts are more highly conserved than zygotic genes, those maternal transcripts that are completely degraded at the MZT vary dramatically between species. We also show that hundreds of genes have different isoform usage between the maternal and zygotic genomes. Our work suggests that maternal transcript deposition and early zygotic transcription are remarkably dynamic over evolutionary time, despite the widespread conservation of early developmental processes.
Collapse
|
57
|
Abstract
Understanding phylogenetic relationships among taxa is key to designing and implementing comparative analyses. The genus Drosophila, which contains over 1600 species, is one of the most important model systems in the biological sciences. For over a century, one species in this group, Drosophila melanogaster, has been key to studies of animal development and genetics, genome organization and evolution, and human disease. As whole-genome sequencing becomes more cost-effective, there is increasing interest in other members of this morphologically, ecologically, and behaviorally diverse genus. Phylogenetic relationships within Drosophila are complicated, and the goal of this paper is to provide a review of the recent taxonomic changes and phylogenetic relationships in this genus to aid in further comparative studies.
Collapse
|
58
|
Gildor T, Smadar BTDL. Comparative Studies of Gene Expression Kinetics: Methodologies and Insights on Development and Evolution. Front Genet 2018; 9:339. [PMID: 30186312 PMCID: PMC6113378 DOI: 10.3389/fgene.2018.00339] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/09/2018] [Indexed: 11/13/2022] Open
Abstract
Across the animal kingdom, embryos of closely related species show high morphological similarity despite genetic and environmental distances. Deciphering the molecular mechanisms that underlie morphological conservation and those that support embryonic adaptation are keys to understand developmental robustness and evolution. Comparative studies of developmental gene regulatory networks can track the genetic changes that lead to evolutionary novelties. However, these studies are limited to a relatively small set of genes and demand extensive experimental efforts. An alternative approach enabled by next-generation sequencing, is to compare the expression kinetic of large sets of genes between different species. The advantages of these comparisons are that they can be done relatively easily, for any species and they provide information of all expressed genes. The challenge in these experiments is to compare the kinetic profiles of thousands of genes between species that develop in different rates. Here we review recent comparative studies that tackled the challenges of accurate staging and large-scale analyses using different computational approaches. These studies reveal how correct temporal scaling exposes the striking conservation of developmental gene expression between morphologically similar species. Different clustering approaches are used to address various comparative questions and identify the conservation and divergence of large gene sets. We discuss the unexpected contribution of housekeeping genes to the interspecies correlations and how this contribution distorts the hourglass pattern generated by developmental genes. Overall, we demonstrate how comparative studies of gene expression kinetics can provide novel insights into the developmental constraints and plasticity that shape animal body plans.
Collapse
Affiliation(s)
- Tsvia Gildor
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | - Ben-Tabou de-Leon Smadar
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| |
Collapse
|
59
|
Donoughe S, Kim C, Extavour CG. High-throughput live-imaging of embryos in microwell arrays using a modular specimen mounting system. Biol Open 2018; 7:bio031260. [PMID: 29712638 PMCID: PMC6078342 DOI: 10.1242/bio.031260] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 04/03/2018] [Indexed: 01/09/2023] Open
Abstract
High-throughput live-imaging of embryos is an essential technique in developmental biology, but it is difficult and costly to mount and image embryos in consistent conditions. Here, we present OMMAwell, a simple, reusable device to easily mount dozens of embryos in arrays of agarose microwells with customizable dimensions and spacing. OMMAwell can be configured to mount specimens for upright or inverted microscopes, and includes a reservoir to hold live-imaging medium to maintain constant moisture and osmolarity of specimens during time-lapse imaging. All device components can be fabricated by cutting pieces from a sheet of acrylic using a laser cutter or by making them with a 3D printer. We demonstrate how to design a custom mold and use it to live-image dozens of embryos at a time. We include descriptions, schematics, and design files for 13 additional molds for nine animal species, including most major traditional laboratory models and a number of emerging model systems. Finally, we provide instructions for researchers to customize OMMAwell inserts for embryos or tissues not described herein.
Collapse
Affiliation(s)
- Seth Donoughe
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge MA 02138, USA
| | - Chiyoung Kim
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge MA 02138, USA
| | - Cassandra G Extavour
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge MA 02138, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge MA 02138, USA
| |
Collapse
|
60
|
|
61
|
Khoueiry P, Girardot C, Ciglar L, Peng PC, Gustafson EH, Sinha S, Furlong EE. Uncoupling evolutionary changes in DNA sequence, transcription factor occupancy and enhancer activity. eLife 2017; 6. [PMID: 28792889 PMCID: PMC5550276 DOI: 10.7554/elife.28440] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 07/21/2017] [Indexed: 12/15/2022] Open
Abstract
Sequence variation within enhancers plays a major role in both evolution and disease, yet its functional impact on transcription factor (TF) occupancy and enhancer activity remains poorly understood. Here, we assayed the binding of five essential TFs over multiple stages of embryogenesis in two distant Drosophila species (with 1.4 substitutions per neutral site), identifying thousands of orthologous enhancers with conserved or diverged combinatorial occupancy. We used these binding signatures to dissect two properties of developmental enhancers: (1) potential TF cooperativity, using signatures of co-associations and co-divergence in TF occupancy. This revealed conserved combinatorial binding despite sequence divergence, suggesting protein-protein interactions sustain conserved collective occupancy. (2) Enhancer in-vivo activity, revealing orthologous enhancers with conserved activity despite divergence in TF occupancy. Taken together, we identify enhancers with diverged motifs yet conserved occupancy and others with diverged occupancy yet conserved activity, emphasising the need to functionally measure the effect of divergence on enhancer activity.
Collapse
Affiliation(s)
- Pierre Khoueiry
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Charles Girardot
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Lucia Ciglar
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Pei-Chen Peng
- Carl R. Woese Institute of Genomic Biology, University of Illinois, Champaign, United States
| | - E Hilary Gustafson
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Saurabh Sinha
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany.,Carl R. Woese Institute of Genomic Biology, University of Illinois, Champaign, United States
| | - Eileen Em Furlong
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| |
Collapse
|
62
|
Imag(in)ing growth and form. Mech Dev 2017; 145:13-21. [DOI: 10.1016/j.mod.2017.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 03/21/2017] [Accepted: 03/23/2017] [Indexed: 01/03/2023]
|
63
|
Amourda C, Saunders TE. Gene expression boundary scaling and organ size regulation in the Drosophila embryo. Dev Growth Differ 2017; 59:21-32. [PMID: 28093727 DOI: 10.1111/dgd.12333] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 11/22/2016] [Accepted: 11/23/2016] [Indexed: 12/21/2022]
Abstract
How the shape and size of tissues and organs is regulated during development is a major question in developmental biology. Such regulation relies upon both intrinsic cues (such as signaling networks) and extrinsic inputs (such as from neighboring tissues). Here, we focus on pattern formation and organ development during Drosophila embryogenesis. In particular, we outline the importance of both biochemical and mechanical tissue-tissue interactions in size regulation. We describe how the Drosophila embryo can potentially provide novel insights into how shape and size are regulated during development. We focus on gene expression boundary scaling in the early embryo and how size is regulated in three organs (hindgut, trachea, and ventral nerve cord) later in development, with particular focus on the role of tissue-tissue interactions. Overall, we demonstrate that Drosophila embryogenesis provides a suitable model system for studying spatial and temporal scaling and size control in vivo.
Collapse
Affiliation(s)
- Christopher Amourda
- Mechanobiology Institute, National University of Singapore, T-Lab, #10-01, 5A Engineering Drive 1, 117411, Singapore
| | - Timothy E Saunders
- Mechanobiology Institute, National University of Singapore, T-Lab, #10-01, 5A Engineering Drive 1, 117411, Singapore.,Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, 117543, Singapore.,Institute Of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
| |
Collapse
|
64
|
Hironaka KI, Morishita Y. Adaptive significance of critical weight for metamorphosis in holometabolous insects. J Theor Biol 2017; 417:68-83. [PMID: 28095304 DOI: 10.1016/j.jtbi.2017.01.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 11/25/2022]
Abstract
Holometabolous insect larvae become committed to metamorphosis when they reach a critical weight. Although the physiological mechanisms involved in this process have been well-studied, the adaptive significance of the critical weight remains unclear. Here, we developed a life history model for holometabolous insects and evaluated it from the viewpoint of optimal energy allocation. We found that, without a priori assumptions about critical weight, the optimal growth schedule is always biphasic: larval tissues grow predominately until they reach a certain threshold, after which the imaginal tissues begin rapid growth, suggesting that the emergence of a critical weight as a phase-transition point is a natural consequence of optimal growth scheduling. Our model predicts the optimal timing of critical-weight attainment, in agreement with observations in phylogenetically-distinct species. Furthermore, it also predicts the scaling of growth scheduling against environmental change, i.e., the relative value and timing of the critical weight should be constant, thus providing a general interpretation of observed phenotypic plasticity. This scaling relationship allows the classification of adaptive responses in critical weight into five possible types that reflect the ecological features of focal insects. In this manner, our theory and its consistency with experimental observations demonstrate the adaptive significance of critical weight.
Collapse
Affiliation(s)
- Ken-Ichi Hironaka
- Quantitative Biology Center, RIKEN, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Department of Biological Sciences, Osaka University, 1-1 Machikaneyama-cho,, Toyonaka, Osaka 560-0043, Japan
| | - Yoshihiro Morishita
- Quantitative Biology Center, RIKEN, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
| |
Collapse
|
65
|
Horváth B, Betancourt AJ, Kalinka AT. A novel method for quantifying the rate of embryogenesis uncovers considerable genetic variation for the duration of embryonic development in Drosophila melanogaster. BMC Evol Biol 2016; 16:200. [PMID: 27717305 PMCID: PMC5054588 DOI: 10.1186/s12862-016-0776-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 09/29/2016] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Embryogenesis is a highly conserved, canalized process, and variation in the duration of embryogenesis (DOE), i.e., time from egg lay to hatching, has a potentially profound effect on the outcome of within- and between-species competition. There is both intra- and inter-specific variation in this trait, which may provide important fuel for evolutionary processes, particularly adaptation. However, while genetic variation underlying simpler morphological traits, or with large phenotypic effects is well described in the literature, less is known about the underlying genetics of traits, such as DOE, partly due to a lack of tools with which to study them. RESULTS Here, we establish a novel microscope-based assay to survey genetic variation for the duration of embryogenesis (DOE). First, to establish the potential importance of DOE in competitive fitness, we performed a set of experiments where we experimentally manipulated the time until hatching, and show that short hatching times result in priority effect in the form of improved larval competitive ability. We then use our assay to measure DOE for 43 strains from the Drosophila Genetic Reference Panel (DGRP). Our assay greatly simplifies the measurement of DOE, making it possible to precisely quantify this trait for 59,295 individual embryos (mean ± S.D. of 1103 ± 293 per DGRP strain, and 1002 ± 203 per control). We find extensive genetic variation in DOE, with a 15 % difference in rate between the slowest and fastest strains measured, and 89 % of phenotypic variation due to DGRP strain. Using sequence information from the DGRP, we perform a genome-wide association study, which suggests that some well-known developmental genes affect the speed of embryonic development. CONCLUSIONS We showed that the duration of embryogenesis (DOE) can be efficiently and precisely measured in Drosophila, and that the DGRP strains show remarkable variation in DOE. A genome-wide analysis suggests that some well-known developmental genes are potentially associated with DOE. Further functional assays, or transcriptomic analysis of embryos from the DGRP, can validate the role of our candidates in early developmental processes.
Collapse
Affiliation(s)
- Barbara Horváth
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, A-1210, Vienna, Austria. .,Vienna Graduate School of Population Genetics, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna, A-1210, Austria.
| | - Andrea J Betancourt
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, A-1210, Vienna, Austria
| | - Alex T Kalinka
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, A-1210, Vienna, Austria
| |
Collapse
|
66
|
Tran M, Tsarouhas V, Kegel A. Early development of Drosophila embryos requires Smc5/6 function during oogenesis. Biol Open 2016; 5:928-41. [PMID: 27288507 PMCID: PMC4958276 DOI: 10.1242/bio.019000] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Mutations in structural maintenance of chromosomes (Smc) proteins are frequently associated with chromosomal abnormalities commonly observed in developmental disorders. However, the role of Smc proteins in development still remains elusive. To investigate Smc5/6 function during early embryogenesis we examined smc5 and smc6 mutants of the fruit fly Drosophila melanogaster using a combination of reverse genetics and microscopy approaches. Smc5/6 exhibited a maternally contributed function in maintaining chromosome stability during early embryo development, which manifested as female subfertility in its absence. Loss of Smc5/6 caused an arrest and a considerable delay in embryo development accompanied by fragmented nuclei and increased anaphase-bridge formation, respectively. Surprisingly, early embryonic arrest was attributable to the absence of Smc5/6 during oogenesis, which resulted in insufficient repair of pre-meiotic and meiotic DNA double-strand breaks. Thus, our findings contribute to the understanding of Smc proteins in higher eukaryotic development by highlighting a maternal function in chromosome maintenance and a link between oogenesis and early embryogenesis. Summary: Early emerging problems during oogenesis, such as DNA double-strand breaks, can affect chromosome duplication and segregation in embryogenesis in Drosophila. Moreover, environmental cues including temperature are important for proper oogenesis.
Collapse
Affiliation(s)
- Martin Tran
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm S-17177, Sweden
| | - Vasilios Tsarouhas
- Department of Molecular Bioscience, The Wenner-Gren Institute, Stockholm University, Stockholm S-10691, Sweden
| | - Andreas Kegel
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm S-17177, Sweden
| |
Collapse
|
67
|
Differential Electrophysiological Responses to Odorant Isotopologues in Drosophilid Antennae. eNeuro 2016; 3:eN-NWR-0152-15. [PMID: 27351023 PMCID: PMC4913217 DOI: 10.1523/eneuro.0152-15.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 04/08/2016] [Accepted: 05/02/2016] [Indexed: 12/31/2022] Open
Abstract
Olfaction presents the ultimate challenge to molecular recognition as thousands of molecules have to be recognized by far fewer olfactory receptors. We have presented evidence that Drosophila readily distinguish odorants based on their molecular vibrations using a battery of behavioral assays suggesting engagement of a molecular vibration-sensing component. Here we interrogate electrophysiologically the antennae of four Drosophilids and demonstrate conserved differential response amplitudes to aldehydes, alcohols, ketones, nitriles, and their deuterated isotopologues. Certain deuterated odorants evoked larger electroantennogram (EAG) amplitudes, while the response to the normal odorant was elevated in others. Significantly, benzonitrile isotopologues were not distinguishable as predicted. This suggests that isotopologue-specific EAG amplitudes result from differential activation of specific olfactory receptors. In support of this, odorants with as few as two deuteria evoke distinct EAG amplitudes from their normal isotopologues, and this is independent of the size of the deuterated molecule. Importantly, we find no evidence that these isotopologue-specific amplitudes depend on perireceptor mechanisms or other pertinent physical property of the deuterated odorants. Rather, our results strongly suggest that Drosophilid olfactory receptors are activated by molecular vibrations differentiating similarly sized and shaped odorants in vivo, yielding sufficient differential information to drive behavioral choices.
Collapse
|
68
|
Ben-Tabou de-Leon S. Robustness and Accuracy in Sea Urchin Developmental Gene Regulatory Networks. Front Genet 2016; 7:16. [PMID: 26913048 PMCID: PMC4753288 DOI: 10.3389/fgene.2016.00016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/28/2016] [Indexed: 11/13/2022] Open
Abstract
Developmental gene regulatory networks robustly control the timely activation of regulatory and differentiation genes. The structure of these networks underlies their capacity to buffer intrinsic and extrinsic noise and maintain embryonic morphology. Here I illustrate how the use of specific architectures by the sea urchin developmental regulatory networks enables the robust control of cell fate decisions. The Wnt-βcatenin signaling pathway patterns the primary embryonic axis while the BMP signaling pathway patterns the secondary embryonic axis in the sea urchin embryo and across bilateria. Interestingly, in the sea urchin in both cases, the signaling pathway that defines the axis controls directly the expression of a set of downstream regulatory genes. I propose that this direct activation of a set of regulatory genes enables a uniform regulatory response and a clear cut cell fate decision in the endoderm and in the dorsal ectoderm. The specification of the mesodermal pigment cell lineage is activated by Delta signaling that initiates a triple positive feedback loop that locks down the pigment specification state. I propose that the use of compound positive feedback circuitry provides the endodermal cells enough time to turn off mesodermal genes and ensures correct mesoderm vs. endoderm fate decision. Thus, I argue that understanding the control properties of repeatedly used regulatory architectures illuminates their role in embryogenesis and provides possible explanations to their resistance to evolutionary change.
Collapse
|
69
|
Gouvêa DY, Aprison EZ, Ruvinsky I. Experience Modulates the Reproductive Response to Heat Stress in C. elegans via Multiple Physiological Processes. PLoS One 2015; 10:e0145925. [PMID: 26713620 PMCID: PMC4699941 DOI: 10.1371/journal.pone.0145925] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 12/10/2015] [Indexed: 11/29/2022] Open
Abstract
Natural environments are considerably more variable than laboratory settings and often involve transient exposure to stressful conditions. To fully understand how organisms have evolved to respond to any given stress, prior experience must therefore be considered. We investigated the effects of individual and ancestral experience on C. elegans reproduction. We documented ways in which cultivation at 15°C or 25°C affects developmental time, lifetime fecundity, and reproductive performance after severe heat stress that exceeds the fertile range of the organism but is compatible with survival and future fecundity. We found that experience modulates multiple aspects of reproductive physiology, including the male and female germ lines and the interaction between them. These responses vary in their environmental sensitivity, suggesting the existence of complex mechanisms for coping with unpredictable and stressful environments.
Collapse
Affiliation(s)
- Devin Y. Gouvêa
- Committee on Conceptual and Historical Studies of Science, The University of Chicago, Chicago, Illinois, United States of America
- Committee on Evolutionary Biology, The University of Chicago, Chicago, Illinois, United States of America
| | - Erin Z. Aprison
- Department of Ecology and Evolution, The University of Chicago, Chicago, Illinois, United States of America
| | - Ilya Ruvinsky
- Committee on Evolutionary Biology, The University of Chicago, Chicago, Illinois, United States of America
- Department of Ecology and Evolution, The University of Chicago, Chicago, Illinois, United States of America
- Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois, United States of America
| |
Collapse
|
70
|
Abstract
We previously demonstrated that, while changes in temperature produce dramatic shifts in the time elapsed during
Drosophila melanogaster embryogenesis, the relative timing of events within embryogenesis does not change. However, it was unclear if this uniform scaling is an intrinsic property of developing embryos, or if it is specific to thermal fluctuations. To investigate this, here we characterize the embryonic response to changes in oxygen concentration, which also impact developmental rate, using time-lapse imaging, and find it fundamentally different from the temperature response. Most notably, changes in oxygen levels drive developmental heterochrony, with the timing of several morphological processes showing distinct scaling behaviors. Gut formation is severely slowed by decreases in oxygen, while head involution and syncytial development are less impacted than the rest of development, and the order of several developmental landmarks is inverted at different oxygen levels. These data reveal that the uniform scaling seen with changes in temperature is not a trivial consequence of adjusting developmental rate. The developmental rate changes produced by changing oxygen concentrations dwarf those induced by temperature, and greatly impact survival. While extreme temperatures increase early embryo mortality, mild hypoxia increases arrest and death during mid-embryogenesis and mild hyperoxia increases survival over normoxia.
Collapse
Affiliation(s)
- Steven G Kuntz
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA ; Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Michael B Eisen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA ; Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA, USA ; Department of Integrative Biology, University of California, Berkeley, CA, USA
| |
Collapse
|
71
|
Temporal and spatial dynamics of scaling-specific features of a gene regulatory network in Drosophila. Nat Commun 2015; 6:10031. [PMID: 26644070 PMCID: PMC4686680 DOI: 10.1038/ncomms10031] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 10/28/2015] [Indexed: 01/19/2023] Open
Abstract
A widely appreciated aspect of developmental robustness is pattern formation in proportion to size. But how such scaling features emerge dynamically remains poorly understood. Here we generate a data set of the expression profiles of six gap genes in Drosophila melanogaster embryos that differ significantly in size. Expression patterns exhibit size-dependent dynamics both spatially and temporally. We uncover a dynamic emergence of under-scaling in the posterior, accompanied by reduced expression levels of gap genes near the middle of large embryos. Simulation results show that a size-dependent Bicoid gradient input can lead to reduced Krüppel expression that can have long-range and dynamic effects on gap gene expression in the posterior. Thus, for emergence of scaled patterns, the entire embryo may be viewed as a single unified dynamic system where maternally derived size-dependent information interpreted locally can be propagated in space and time as governed by the dynamics of a gene regulatory network. How pattern formation is regulated relative to the size of an organism is unclear. Here, Wu et al. take data from gap gene expression in flies of different sizes together with simulations, identifying how scaling emerges dynamically and that local patterning influences global gene regulatory networks.
Collapse
|
72
|
Fried P, Iber D. Read-Out of Dynamic Morphogen Gradients on Growing Domains. PLoS One 2015; 10:e0143226. [PMID: 26599604 PMCID: PMC4657938 DOI: 10.1371/journal.pone.0143226] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 10/05/2015] [Indexed: 01/12/2023] Open
Abstract
Quantitative data from the Drosophila wing imaginal disc reveals that the amplitude of the Decapentaplegic (Dpp) morphogen gradient increases continuously. It is an open question how cells can determine their relative position within a domain based on a continuously increasing gradient. Here we show that pre-steady state diffusion-based dispersal of morphogens results in a zone within the growing domain where the concentration remains constant over the patterning period. The position of the zone that is predicted based on quantitative data for the Dpp morphogen corresponds to where the Dpp-dependent gene expression boundaries of spalt (sal) and daughters against dpp (dad) emerge. The model also suggests that genes that are scaling and are expressed at lateral positions are either under the control of a different read-out mechanism or under the control of a different morphogen. The patterning mechanism explains the extraordinary robustness that is observed for variations in Dpp production, and offers an explanation for the dual role of Dpp in controlling patterning and growth. Pre-steady-state dynamics are pervasive in morphogen-controlled systems, thus making this a probable general mechanism for the scaled read-out of morphogen gradients in growing developmental systems.
Collapse
Affiliation(s)
- Patrick Fried
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
- SIB Swiss Institute of Bioinformatics, Basel, Switzerland
| | - Dagmar Iber
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
- SIB Swiss Institute of Bioinformatics, Basel, Switzerland
- * E-mail:
| |
Collapse
|
73
|
Paris M, Villalta JE, Eisen MB, Lott SE. Sex Bias and Maternal Contribution to Gene Expression Divergence in Drosophila Blastoderm Embryos. PLoS Genet 2015; 11:e1005592. [PMID: 26485701 PMCID: PMC4618353 DOI: 10.1371/journal.pgen.1005592] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 09/18/2015] [Indexed: 11/27/2022] Open
Abstract
Early embryogenesis is a unique developmental stage where genetic control of development is handed off from mother to zygote. Yet the contribution of this transition to the evolution of gene expression is poorly understood. Here we study two aspects of gene expression specific to early embryogenesis in Drosophila: sex-biased gene expression prior to the onset of canonical X chromosomal dosage compensation, and the contribution of maternally supplied mRNAs. We sequenced mRNAs from individual unfertilized eggs and precisely staged and sexed blastoderm embryos, and compared levels between D. melanogaster, D. yakuba, D. pseudoobscura and D. virilis. First, we find that mRNA content is highly conserved for a given stage and that studies relying on pooled embryos likely systematically overstate the degree of gene expression divergence. Unlike studies done on larvae and adults where most species show a larger proportion of genes with male-biased expression, we find that transcripts in Drosophila embryos are largely female-biased in all species, likely due to incomplete dosage compensation prior to the activation of the canonical dosage compensation mechanism. The divergence of sex-biased gene expression across species is observed to be often due to lineage-specific decrease of expression; the most drastic example of which is the overall reduction of male expression from the neo-X chromosome in D. pseudoobscura, leading to a pervasive female-bias on this chromosome. We see no evidence for a faster evolution of expression on the X chromosome in embryos (no “faster-X” effect), unlike in adults, and contrary to a previous study on pooled non-sexed embryos. Finally, we find that most genes are conserved in regard to their maternal or zygotic origin of transcription, and present evidence that differences in maternal contribution to the blastoderm transcript pool may be due to species-specific divergence of transcript degradation rates. The early embryonic stage of development is unique as this stage begins under the genetic control of the mother and transitions to genetic control of the zygote. In order to investigate how these developmental specificities have shaped gene expression evolution, we studied the contribution of maternal gene expression to the pool of transcripts in the early embryo and how gene expression differs in early female and male embryos. We find extensive female-bias in gene expression, something not observed in adults. This is largely due to the delay in the establishment of a mechanism that balances gene expression from the differing number of X chromosomes in females and males. The maternal contribution to the transcript pool in the embryo is largely conserved over species, with some exceptions. However, there may also be some species-specific differences in the degradation rate of maternal transcripts, an often-overlooked contributor to variation in transcript level.
Collapse
Affiliation(s)
- Mathilde Paris
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail: (MP); (SEL)
| | - Jacqueline E. Villalta
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, United States of America
| | - Michael B. Eisen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, United States of America
| | - Susan E. Lott
- Department of Evolution and Ecology, University of California, Davis, Davis, California, United States of America
- * E-mail: (MP); (SEL)
| |
Collapse
|
74
|
Probing the impact of temperature on molecular events in a developmental system. Sci Rep 2015; 5:13124. [PMID: 26286011 PMCID: PMC4541335 DOI: 10.1038/srep13124] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 07/16/2015] [Indexed: 01/19/2023] Open
Abstract
A well-appreciated general feature of development is the ability to achieve a normal outcome despite the inevitable variability at molecular, genetic, or environmental levels. But it is not well understood how changes in a global factor such as temperature bring about specific challenges to a developmental system in molecular terms. Here we address this question using early Drosophila embryos where the maternal gradient Bicoid (Bcd) instructs anterior-patterning (AP) patterning. We show that temperature can impact the amplitude of the Bcd gradient in the embryo. To evaluate how molecular decisions are made at different temperatures, we quantify Bcd concentrations and the expression of its target gene hunchback (hb) in individual embryos. Our results suggest a relatively robust Bcd concentration threshold in inducing hb transcription within a temperature range. Our results also reveal a complex nature of the effects of temperature on the progressions of developmental and molecular events of the embryo. Our study thus advances the concept of developmental robustness by quantitatively elaborating specific features and challenges—imposed by changes in temperature—that an embryo must resolve.
Collapse
|
75
|
Comparative Study of Regulatory Circuits in Two Sea Urchin Species Reveals Tight Control of Timing and High Conservation of Expression Dynamics. PLoS Genet 2015; 11:e1005435. [PMID: 26230518 PMCID: PMC4521883 DOI: 10.1371/journal.pgen.1005435] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 07/08/2015] [Indexed: 12/25/2022] Open
Abstract
Accurate temporal control of gene expression is essential for normal development and must be robust to natural genetic and environmental variation. Studying gene expression variation within and between related species can delineate the level of expression variability that development can tolerate. Here we exploit the comprehensive model of sea urchin gene regulatory networks and generate high-density expression profiles of key regulatory genes of the Mediterranean sea urchin, Paracentrotus lividus (Pl). The high resolution of our studies reveals highly reproducible gene initiation times that have lower variation than those of maximal mRNA levels between different individuals of the same species. This observation supports a threshold behavior of gene activation that is less sensitive to input concentrations. We then compare Mediterranean sea urchin gene expression profiles to those of its Pacific Ocean relative, Strongylocentrotus purpuratus (Sp). These species shared a common ancestor about 40 million years ago and show highly similar embryonic morphologies. Our comparative analyses of five regulatory circuits operating in different embryonic territories reveal a high conservation of the temporal order of gene activation but also some cases of divergence. A linear ratio of 1.3-fold between gene initiation times in Pl and Sp is partially explained by scaling of the developmental rates with temperature. Scaling the developmental rates according to the estimated Sp-Pl ratio and normalizing the expression levels reveals a striking conservation of relative dynamics of gene expression between the species. Overall, our findings demonstrate the ability of biological developmental systems to tightly control the timing of gene activation and relative dynamics and overcome expression noise induced by genetic variation and growth conditions.
Collapse
|
76
|
LaRue KM, Clemens J, Berman GJ, Murthy M. Acoustic duetting in Drosophila virilis relies on the integration of auditory and tactile signals. eLife 2015; 4:e07277. [PMID: 26046297 PMCID: PMC4456510 DOI: 10.7554/elife.07277] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 05/11/2015] [Indexed: 01/26/2023] Open
Abstract
Many animal species, including insects, are capable of acoustic duetting, a complex social behavior in which males and females tightly control the rate and timing of their courtship song syllables relative to each other. The mechanisms underlying duetting remain largely unknown across model systems. Most studies of duetting focus exclusively on acoustic interactions, but the use of multisensory cues should aid in coordinating behavior between individuals. To test this hypothesis, we develop Drosophila virilis as a new model for studies of duetting. By combining sensory manipulations, quantitative behavioral assays, and statistical modeling, we show that virilis females combine precisely timed auditory and tactile cues to drive song production and duetting. Tactile cues delivered to the abdomen and genitalia play the larger role in females, as even headless females continue to coordinate song production with courting males. These data, therefore, reveal a novel, non-acoustic, mechanism for acoustic duetting. Finally, our results indicate that female-duetting circuits are not sexually differentiated, as males can also produce 'female-like' duets in a context-dependent manner.
Collapse
Affiliation(s)
- Kelly M LaRue
- Princeton Neuroscience Institute, Princeton University, Princeton, United States
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Jan Clemens
- Princeton Neuroscience Institute, Princeton University, Princeton, United States
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Gordon J Berman
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, United States
| | - Mala Murthy
- Princeton Neuroscience Institute, Princeton University, Princeton, United States
- Department of Molecular Biology, Princeton University, Princeton, United States
| |
Collapse
|
77
|
Welte MA. As the fat flies: The dynamic lipid droplets of Drosophila embryos. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1156-85. [PMID: 25882628 DOI: 10.1016/j.bbalip.2015.04.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 03/31/2015] [Accepted: 04/06/2015] [Indexed: 01/09/2023]
Abstract
Research into lipid droplets is rapidly expanding, and new cellular and organismal roles for these lipid-storage organelles are continually being discovered. The early Drosophila embryo is particularly well suited for addressing certain questions in lipid-droplet biology and combines technical advantages with unique biological phenomena. This review summarizes key features of this experimental system and the techniques available to study it, in order to make it accessible to researchers outside this field. It then describes the two topics most heavily studied in this system, lipid-droplet motility and protein sequestration on droplets, discusses what is known about the molecular players involved, points to open questions, and compares the results from Drosophila embryo studies to what it is known about lipid droplets in other systems.
Collapse
Affiliation(s)
- Michael A Welte
- Department of Biology University of Rochester, RC Box 270211, 317 Hutchison Hall, Rochester, NY 14627, USA.
| |
Collapse
|
78
|
Bellemer A. Thermotaxis, circadian rhythms, and TRP channels in Drosophila. Temperature (Austin) 2015; 2:227-43. [PMID: 27227026 PMCID: PMC4843867 DOI: 10.1080/23328940.2015.1004972] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/31/2014] [Accepted: 01/01/2015] [Indexed: 01/24/2023] Open
Abstract
The fruit fly Drosophila melanogaster is a poikilothermic organism that must detect and respond to both fine and coarse changes in environmental temperature in order maintain optimal body temperature, synchronize behavior to daily temperature fluctuations, and to avoid potentially injurious environmental hazards. Members of the Transient Receptor Potential (TRP) family of cation channels are well known for their activation by changes in temperature and their essential roles in sensory transduction in both invertebrates and vertebrates. The Drosophila genome encodes 13 TRP channels, and several of these have key sensory transduction and modulatory functions in allowing larval and adult flies to make fine temperature discriminations to attain optimal body temperature, detect and avoid large environmental temperature fluctuations, and make rapid escape responses to acutely noxious stimuli. Drosophila use multiple, redundant signaling pathways and neural circuits to execute these behaviors in response to both increases and decreases in temperature of varying magnitudes and time scales. A plethora of powerful molecular and genetic tools and the fly's simple, well-characterized nervous system have given Drosophila neurobiologists a powerful platform to study the cellular and molecular mechanisms of TRP channel function and how these mechanisms are conserved in vertebrates, as well as how these channels function within sensorimotor circuits to generate both simple and complex thermosensory behaviors.
Collapse
Key Words
- A1, 1st Antennal Segment
- A2, 2nd Antennal Segment
- A3, 3rd Antennal Segment
- AC, Anterior Cell
- AL, Antennal Lobe
- AR, Arista
- Clk, Clock protein
- Cry, Cryptochrome
- Cyc, Cycle protein
- DN1, DN2, DN3, Dorsal Neuron group 1, 2, 3
- Dbt, Double Time protein
- Drosophila melanogaster
- GFP, Green Fluorescent Protein
- GPCR, G Protein-Coupled Receptor
- LN, Lateral Neuron
- LNd, Dorsal Lateral Neuron
- LNv, Ventral Lateral Neuron
- LPN, Lateral Posterior Neuron
- NEL, Nocifensive Escape Locomotion
- PAP, Proximal Antennal Protocerebrum
- PDF, Pigment Dispersing Factor
- PKD1, Polycistic Kidney Disease 1
- PLC, Phospholipase C
- Per, Period protein
- RNAi, RNA interference
- SAC, Sacculus
- SLPR, Superior Lateral Protocerebrum
- SOG, Suboesophageal Ganglion
- TRP channels
- TRP, Transient Receptor Potential
- TRPA, Transient Receptor Potential, group A (ankyrin repeat)
- TRPA1
- TRPC, Transient Receptor Potential, group C (canonical)
- TRPL, TRP-Like
- TRPM, Transient Receptor Potential, group M (melastatin)
- TRPP, Transient Receptor Potential, group P (polycystic)
- TRPV, Transient Receptor Potential, group V (vanilloid)
- Tim, Timeless protein
- VFP, Venus Fluorescent Protein
- circadian rhythms
- lLNv, Ventral Lateral Neuron, large cell body
- mdIV, Multidendritic Neuron, class IV
- nociception
- sLNv, Ventral Lateral Neuron, small cell body
- thermoTRP, thermosensitive TRP channel
- thermosensation
- thermotaxis
Collapse
Affiliation(s)
- Andrew Bellemer
- Department of Biology; Appalachian State University ; Boone, NC, USA
| |
Collapse
|
79
|
Temperature Dependence of Cell Division Timing Accounts for a Shift in the Thermal Limits of C. elegans and C. briggsae. Cell Rep 2015; 10:647-653. [DOI: 10.1016/j.celrep.2015.01.006] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 12/01/2014] [Accepted: 12/29/2014] [Indexed: 01/08/2023] Open
|
80
|
Rieder LE, Savva YA, Reyna MA, Chang YJ, Dorsky JS, Rezaei A, Reenan RA. Dynamic response of RNA editing to temperature in Drosophila. BMC Biol 2015; 13:1. [PMID: 25555396 PMCID: PMC4299485 DOI: 10.1186/s12915-014-0111-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 12/15/2014] [Indexed: 12/22/2022] Open
Abstract
Background Adenosine-to-inosine RNA editing is a highly conserved process that post-transcriptionally modifies mRNA, generating proteomic diversity, particularly within the nervous system of metazoans. Transcripts encoding proteins involved in neurotransmission predominate as targets of such modifications. Previous reports suggest that RNA editing is responsive to environmental inputs in the form of temperature alterations. However, the molecular determinants underlying temperature-dependent RNA editing responses are not well understood. Results Using the poikilotherm Drosophila, we show that acute temperature alterations within a normal physiological range result in substantial changes in RNA editing levels. Our examination of particular sites reveals diversity in the patterns with which editing responds to temperature, and these patterns are conserved across five species of Drosophilidae representing over 10 million years of divergence. In addition, we show that expression of the editing enzyme, ADAR (adenosine deaminase acting on RNA), is dramatically decreased at elevated temperatures, partially, but not fully, explaining some target responses to temperature. Interestingly, this reduction in editing enzyme levels at elevated temperature is only partially reversed by a return to lower temperatures. Lastly, we show that engineered structural variants of the most temperature-sensitive editing site, in a sodium channel transcript, perturb thermal responsiveness in RNA editing profile for a particular RNA structure. Conclusions Our results suggest that the RNA editing process responds to temperature alterations via two distinct molecular mechanisms: through intrinsic thermo-sensitivity of the RNA structures that direct editing, and due to temperature sensitive expression or stability of the RNA editing enzyme. Environmental cues, in this case temperature, rapidly reprogram the Drosophila transcriptome through RNA editing, presumably resulting in altered proteomic ratios of edited and unedited proteins. Electronic supplementary material The online version of this article (doi:10.1186/s12915-014-0111-3) contains supplementary material, which is available to authorized users.
Collapse
|
81
|
Abstract
Using a well-adapted Drosophila subobscura population (Avala, Serbia), a drastic experiment of inbreeding was carried out to assess whether the expected level of homozygosity could be reached or if other evolutionary forces affected the process. In general, no significant changes of inversion (or arrangement) frequencies were detected after 12 brother-sister mating generations. Furthermore, no significant differences were obtained between observed and expected (under the inbreeding model) karyotypic frequencies. Thus, these results seemed to indicate that the main evolutionary factor in the experiment was inbreeding. However, in the G12 generation, complete chromosomal fixation was reached only in two out of the eight final inbred lines. In these lines, the chromosomal compositions were difficult to interpret, but they could be likely a consequence of adaptation to particular laboratory conditions (constant 18 °C, food, light period, etc.). Finally, in a second experiment, the inbred lines presented higher fertility at 18 °C than at 13 °C. Also, there was a significant line effect on fertility: inbred line number 6 (A1, J1, U1+2; U1+2+6, E8, and O3+4+7) presented the highest values, which maybe the result of an adaptation to laboratory conditions. Thus, the results obtained in our experiments reflect the adaptive potential of D. subobscura inversions.
Collapse
Affiliation(s)
- Goran Zivanovic
- a Department of Genetics, Institute for Biological Research "Sinisa Stankovic", University of Belgrade, Belgrade, Serbia
| | | | | |
Collapse
|
82
|
Gaspar I, Yu YV, Cotton SL, Kim DH, Ephrussi A, Welte MA. Klar ensures thermal robustness of oskar localization by restraining RNP motility. ACTA ACUST UNITED AC 2014; 206:199-215. [PMID: 25049271 PMCID: PMC4107779 DOI: 10.1083/jcb.201310010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
When temperature fluctuation threatens the fidelity of Drosophila oogenesis, Klar restrains posterior-ward translocation of oskar mRNA, thereby adapting the rate of oskar delivery to the capacity of the anchoring machinery. Communication usually applies feedback loop–based filters and amplifiers to ensure undistorted delivery of messages. Such an amplifier acts during Drosophila melanogaster midoogenesis, when oskar messenger ribonucleic acid (mRNA) anchoring depends on its own locally translated protein product. We find that the motor regulator Klar β mediates a gain-control process that prevents saturation-based distortions in this positive feedback loop. We demonstrate that, like oskar mRNA, Klar β localizes to the posterior pole of oocytes in a kinesin-1–dependent manner. By live imaging and semiquantitative fluorescent in situ hybridization, we show that Klar β restrains oskar ribonucleoprotein motility and decreases the posterior-ward translocation of oskar mRNA, thereby adapting the rate of oskar delivery to the output of the anchoring machinery. This negative regulatory effect of Klar is particularly important for overriding temperature-induced changes in motility. We conclude that by preventing defects in oskar anchoring, this mechanism contributes to the developmental robustness of a poikilothermic organism living in a variable temperature environment.
Collapse
Affiliation(s)
- Imre Gaspar
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Yanxun V Yu
- Department of Biology, University of Rochester, Rochester, NY 14627
| | - Sean L Cotton
- Department of Biology, Brandeis University, Waltham, MA 02454
| | - Dae-Hwan Kim
- Department of Biology, Brandeis University, Waltham, MA 02454
| | - Anne Ephrussi
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Michael A Welte
- Department of Biology, University of Rochester, Rochester, NY 14627 Department of Biology, Brandeis University, Waltham, MA 02454
| |
Collapse
|
83
|
Ninova M, Ronshaugen M, Griffiths-Jones S. Conserved temporal patterns of microRNA expression in Drosophila support a developmental hourglass model. Genome Biol Evol 2014; 6:2459-67. [PMID: 25169982 PMCID: PMC4202322 DOI: 10.1093/gbe/evu183] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The spatiotemporal control of gene expression is crucial for the successful completion of animal development. The evolutionary constraints on development are particularly strong for the mid-embryonic stage when body segments are specified, as evidenced by a high degree of morphological and protein-coding gene conservation during this period—a phenomenon known as the developmental hourglass. The discovery of microRNA-mediated gene control revealed an entirely new layer of complexity of the molecular networks that orchestrate development. However, the constraints on microRNA developmental expression and evolution, and the implications for animal evolution are less well understood. To systematically explore the conservation of microRNAs during development, we carried out a genome-wide comparative study of microRNA expression levels throughout the ontogenesis of two divergent fruit flies, Drosophila melanogaster and D. virilis. We show that orthologous microRNAs display highly similar temporal profiles regardless of their mutation rates, suggesting that the timely expression of microRNA genes can be more constrained than their sequence. Furthermore, transitions between key developmental events in the different species are accompanied by conserved shifts in microRNA expression profiles, with the mid-embryonic period between gastrulation and segmentation characterized by the highest similarity of microRNA expression. The conservation of microRNA expression therefore displays an hourglass pattern similar to that observed for protein-coding genes.
Collapse
Affiliation(s)
- Maria Ninova
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Matthew Ronshaugen
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Sam Griffiths-Jones
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| |
Collapse
|
84
|
Artieri CG, Fraser HB. Transcript length mediates developmental timing of gene expression across Drosophila. Mol Biol Evol 2014; 31:2879-89. [PMID: 25069653 PMCID: PMC4209130 DOI: 10.1093/molbev/msu226] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The time required to transcribe genes with long primary transcripts may limit their ability to be expressed in cells with short mitotic cycles, a phenomenon termed intron delay. As such short cycles are a hallmark of the earliest stages of insect development, we tested the impact of intron delay on the Drosophila developmental transcriptome. We find that long zygotically expressed genes show substantial delay in expression relative to their shorter counterparts, which is not observed for maternally deposited transcripts. Patterns of RNA-seq coverage along transcripts show that this delay is consistent with their inability to completely transcribe long transcripts, but not with transcriptional initiation-based regulatory control. We further show that highly expressed zygotic genes maintain compact transcribed regions across the Drosophila phylogeny, allowing conservation of embryonic expression patterns. We propose that the physical constraints of intron delay affect patterns of expression and the evolution of gene structure of a substantial portion of the Drosophila transcriptome.
Collapse
|