1
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Weng Y, Murphy CT. Male-specific behavioral and transcriptomic changes in aging C. elegans neurons. iScience 2024; 27:109910. [PMID: 38783998 PMCID: PMC11111838 DOI: 10.1016/j.isci.2024.109910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/20/2024] [Accepted: 05/03/2024] [Indexed: 05/25/2024] Open
Abstract
Aging is a complex biological process with sexually dimorphic aspects. Although cognitive aging of Caenorhabditis elegans hermaphrodites has been studied, less is known about cognitive decline in males. We found that cognitive aging has both sex-shared and sex-dimorphic characteristics, and we identified neuron-specific age-associated sex-differential targets. In addition to sex-shared neuronal aging genes, males differentially downregulate mitochondrial metabolic genes and upregulate GPCR genes with age, while the X chromosome exhibits increased gene expression in hermaphrodites and altered dosage compensation complex expression with age, indicating possible X chromosome dysregulation that contributes to sexual dimorphism in cognitive aging. Finally, the sex-differentially expressed gene hrg-7, an aspartic-type endopeptidase, regulates male cognitive aging but does not affect hermaphrodites' behaviors. These results suggest that males and hermaphrodites exhibit different age-related neuronal changes. This study will strengthen our understanding of sex-specific vulnerability and resilience and identify pathways to target with treatments that could benefit both sexes.
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Affiliation(s)
- Yifei Weng
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
- LSI Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Coleen T. Murphy
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
- LSI Genomics, Princeton University, Princeton, NJ 08544, USA
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2
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Burkhardt RN, Artyukhin AB, Aprison EZ, Curtis BJ, Fox BW, Ludewig AH, Palomino DF, Luo J, Chaturbedi A, Panda O, Wrobel CJJ, Baumann V, Portman DS, Lee SS, Ruvinsky I, Schroeder FC. Sex-specificity of the C. elegans metabolome. Nat Commun 2023; 14:320. [PMID: 36658169 PMCID: PMC9852247 DOI: 10.1038/s41467-023-36040-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 01/13/2023] [Indexed: 01/20/2023] Open
Abstract
Recent studies of animal metabolism have revealed large numbers of novel metabolites that are involved in all aspects of organismal biology, but it is unclear to what extent metabolomes differ between sexes. Here, using untargeted comparative metabolomics for the analysis of wildtype animals and sex determination mutants, we show that C. elegans hermaphrodites and males exhibit pervasive metabolomic differences. Several hundred small molecules are produced exclusively or in much larger amounts in one sex, including a host of previously unreported metabolites that incorporate building blocks from nucleoside, carbohydrate, lipid, and amino acid metabolism. A subset of male-enriched metabolites is specifically associated with the presence of a male germline, whereas enrichment of other compounds requires a male soma. Further, we show that one of the male germline-dependent metabolites, an unusual dipeptide incorporating N,N-dimethyltryptophan, increases food consumption, reduces lifespan, and accelerates the last stage of larval development in hermaphrodites. Our results serve as a foundation for mechanistic studies of how the genetic sex of soma and germline shape the C. elegans metabolome and provide a blueprint for the discovery of sex-dependent metabolites in other animals.
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Affiliation(s)
- Russell N Burkhardt
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Alexander B Artyukhin
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
- Chemistry Department, College of Environmental Science and Forestry, State University of New York, Syracuse, NY, 13210, USA
| | - Erin Z Aprison
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, 60208, USA
| | - Brian J Curtis
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Bennett W Fox
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Andreas H Ludewig
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Diana Fajardo Palomino
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Jintao Luo
- Department of Biomedical Genetics, University of Rochester, Rochester, NY, 14642, USA
- School of Life Sciences, Xiamen University, 361102, Xiamen, Fujian, China
| | - Amaresh Chaturbedi
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Oishika Panda
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Chester J J Wrobel
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Victor Baumann
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Douglas S Portman
- Department of Biomedical Genetics, University of Rochester, Rochester, NY, 14642, USA
| | - Siu Sylvia Lee
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Ilya Ruvinsky
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, 60208, USA.
| | - Frank C Schroeder
- Boyce Thompson Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA.
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3
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Ramos CD, Bohnert KA, Johnson AE. Reproductive tradeoffs govern sexually dimorphic tubular lysosome induction in C. elegans. J Exp Biol 2022; 225:275540. [PMID: 35620964 DOI: 10.1242/jeb.244282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/23/2022] [Indexed: 11/20/2022]
Abstract
Sex-specific differences in animal behavior commonly reflect unique reproductive interests. In the nematode Caenorhabditis elegans, hermaphrodites can reproduce without a mate and thus prioritize feeding to satisfy the high energetic costs of reproduction. However, males, which must mate to reproduce, sacrifice feeding to prioritize mate-searching behavior. Here, we demonstrate that these behavioral differences influence sexual dimorphism at the organelle level; young males raised on a rich food source show constitutive induction of gut tubular lysosomes, a non-canonical lysosome morphology that forms in the gut of hermaphrodites when food is limited or as animals age. We find that constitutive induction of gut tubular lysosomes in males results from self-imposed dietary restriction through daf-7/TGFβ, which promotes exploratory behavior. In contrast, age-dependent induction of gut tubular lysosomes in hermaphrodites is stimulated by self-fertilization activity. Thus, separate reproductive tradeoffs influence tubular lysosome induction in each sex, potentially supporting different requirements for reproductive success.
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Affiliation(s)
- Cara D Ramos
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - K Adam Bohnert
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Alyssa E Johnson
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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Kim D, Kim B. Anatomical and Functional Differences in the Sex-Shared Neurons of the Nematode C. elegans. Front Neuroanat 2022; 16:906090. [PMID: 35601998 PMCID: PMC9121059 DOI: 10.3389/fnana.2022.906090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 04/20/2022] [Indexed: 11/13/2022] Open
Abstract
Studies on sexual dimorphism in the structure and function of the nervous system have been pivotal to understanding sex differences in behavior. Such studies, especially on invertebrates, have shown the importance of neurons specific to one sex (sex-specific neurons) in shaping sexually dimorphic neural circuits. Nevertheless, recent studies using the nematode C. elegans have revealed that the common neurons that exist in both sexes (sex-shared neurons) also play significant roles in generating sex differences in the structure and function of neural circuits. Here, we review the anatomical and functional differences in the sex-shared neurons of C. elegans. These sexually dimorphic characteristics include morphological differences in neurite projection or branching patterns with substantial changes in synaptic connectivity, differences in synaptic connections without obvious structural changes, and functional modulation in neural circuits with no or minimal synaptic connectivity changes. We also cover underlying molecular mechanisms whereby these sex-shared neurons contribute to the establishment of sexually dimorphic circuits during development and function differently between the sexes.
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5
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Mank JE, Rideout EJ. Developmental mechanisms of sex differences: from cells to organisms. Development 2021; 148:272484. [PMID: 34647574 DOI: 10.1242/dev.199750] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Male-female differences in many developmental mechanisms lead to the formation of two morphologically and physiologically distinct sexes. Although this is expected for traits with prominent differences between the sexes, such as the gonads, sex-specific processes also contribute to traits without obvious male-female differences, such as the intestine. Here, we review sex differences in developmental mechanisms that operate at several levels of biological complexity - molecular, cellular, organ and organismal - and discuss how these differences influence organ formation, function and whole-body physiology. Together, the examples we highlight show that one simple way to gain a more accurate and comprehensive understanding of animal development is to include both sexes.
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Affiliation(s)
- Judith E Mank
- Department of Zoology, Biodiversity Research Centre, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.,Biosciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Elizabeth J Rideout
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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6
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Loxterkamp E, Cha J, Wu K, Sullivan J, Holbrook O, Ghaith H, Srun L, Bauer DE. Behavioral Differences between Male and Hermaphrodite C. elegans. MICROPUBLICATION BIOLOGY 2021; 2021:10.17912/micropub.biology.000431. [PMID: 34345807 PMCID: PMC8325061 DOI: 10.17912/micropub.biology.000431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/18/2021] [Accepted: 07/22/2021] [Indexed: 11/06/2022]
Abstract
C. elegans are microscopic nematodes used extensively as a model organism due to their simplicity, allowing researchers to study basic molecular processes in biology. Most C. elegans are hermaphrodites, possessing two X chromosomes and the ability to reproduce asexually, but approximately 0.1% are males, arising due to a spontaneous loss of an X chromosome. In order to evaluate the behavioral sex differences in C. elegans, we expanded upon existing literature and compared spontaneous movement, sensitivity to mechanosensation, and sensitivity to chemosensation between males and hermaphrodites. In our paradigms, we found that males and hermaphrodites exhibit similar spontaneous movement as well as similar slow and sustained behaviors such as chemotaxis, but differ in quick-response to mechanical and chemosensory stimuli.
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Affiliation(s)
- Elizabeth Loxterkamp
- Department of Neuroscience, Wellesley College, Wellesley, Massachusetts, USA,
Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Jaaram Cha
- Department of Neuroscience, Wellesley College, Wellesley, Massachusetts, USA
| | - Katharine Wu
- Department of Neuroscience, Wellesley College, Wellesley, Massachusetts, USA
| | - Janessa Sullivan
- Department of Neuroscience, Wellesley College, Wellesley, Massachusetts, USA
| | - Olivia Holbrook
- Department of Neuroscience, Wellesley College, Wellesley, Massachusetts, USA
| | - Hazar Ghaith
- Department of Neuroscience, Wellesley College, Wellesley, Massachusetts, USA
| | - Lena Srun
- Department of Neuroscience, Wellesley College, Wellesley, Massachusetts, USA
| | - Deborah E. Bauer
- Department of Neuroscience, Wellesley College, Wellesley, Massachusetts, USA,
Correspondence to: Deborah E. Bauer ()
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7
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Meeh KL, Rickel CT, Sansano AJ, Shirangi TR. The development of sex differences in the nervous system and behavior of flies, worms, and rodents. Dev Biol 2021; 472:75-84. [PMID: 33484707 DOI: 10.1016/j.ydbio.2021.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/12/2021] [Accepted: 01/15/2021] [Indexed: 01/14/2023]
Abstract
Understanding how sex differences in innate animal behaviors arise has long fascinated biologists. As a general rule, the potential for sex differences in behavior is built by the developmental actions of sex-specific hormones or regulatory proteins that direct the sexual differentiation of the nervous system. In the last decade, studies in several animal systems have uncovered neural circuit mechanisms underlying discrete sexually dimorphic behaviors. Moreover, how certain hormones and regulatory proteins implement the sexual differentiation of these neural circuits has been illuminated in tremendous detail. Here, we discuss some of these mechanisms with three case-studies-mate recognition in flies, maturation of mating behavior in worms, and play-fighting behavior in young rodents. These studies illustrate general and unique developmental mechanisms to establish sex differences in neuroanatomy and behavior and highlight future challenges for the field.
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Affiliation(s)
- Kristen L Meeh
- Villanova University, Department of Biology, 800 Lancaster Ave, Villanova, PA, 19085, USA
| | - Clare T Rickel
- Villanova University, Department of Biology, 800 Lancaster Ave, Villanova, PA, 19085, USA
| | - Alexander J Sansano
- Villanova University, Department of Biology, 800 Lancaster Ave, Villanova, PA, 19085, USA
| | - Troy R Shirangi
- Villanova University, Department of Biology, 800 Lancaster Ave, Villanova, PA, 19085, USA.
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8
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Wexler J, Delaney EK, Belles X, Schal C, Wada-Katsumata A, Amicucci MJ, Kopp A. Hemimetabolous insects elucidate the origin of sexual development via alternative splicing. eLife 2019; 8:e47490. [PMID: 31478483 PMCID: PMC6721801 DOI: 10.7554/elife.47490] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Accepted: 08/11/2019] [Indexed: 02/02/2023] Open
Abstract
Insects are the only known animals in which sexual differentiation is controlled by sex-specific splicing. The doublesex transcription factor produces distinct male and female isoforms, which are both essential for sex-specific development. dsx splicing depends on transformer, which is also alternatively spliced such that functional Tra is only present in females. This pathway has evolved from an ancestral mechanism where dsx was independent of tra and expressed and required only in males. To reconstruct this transition, we examined three basal, hemimetabolous insect orders: Hemiptera, Phthiraptera, and Blattodea. We show that tra and dsx have distinct functions in these insects, reflecting different stages in the changeover from a transcription-based to a splicing-based mode of sexual differentiation. We propose that the canonical insect tra-dsx pathway evolved via merger between expanding dsx function (from males to both sexes) and narrowing tra function (from a general splicing factor to dedicated regulator of dsx).
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Affiliation(s)
- Judith Wexler
- Department of Evolution and EcologyUniversity of California, DavisDavisUnited States
| | - Emily Kay Delaney
- Department of Evolution and EcologyUniversity of California, DavisDavisUnited States
| | - Xavier Belles
- Institut de Biologia EvolutivaConsejo Superior de Investigaciones Cientificas, Universitat Pompeu FabraBarcelonaSpain
| | - Coby Schal
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighUnited States
| | - Ayako Wada-Katsumata
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighUnited States
| | - Matthew J Amicucci
- Department of ChemistryUniversity of California, DavisDavisUnited States
| | - Artyom Kopp
- Department of Evolution and EcologyUniversity of California, DavisDavisUnited States
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9
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Lawson H, Vuong E, Miller RM, Kiontke K, Fitch DHA, Portman DS. The Makorin lep-2 and the lncRNA lep-5 regulate lin-28 to schedule sexual maturation of the C. elegans nervous system. eLife 2019; 8:e43660. [PMID: 31264582 PMCID: PMC6606027 DOI: 10.7554/elife.43660] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 05/10/2019] [Indexed: 12/30/2022] Open
Abstract
Sexual maturation must occur on a controlled developmental schedule. In mammals, Makorin3 (MKRN3) and the miRNA regulators LIN28A/B are key regulators of this process, but how they act is unclear. In C. elegans, sexual maturation of the nervous system includes the functional remodeling of postmitotic neurons and the onset of adult-specific behaviors. Here, we find that the lin-28-let-7 axis (the 'heterochronic pathway') determines the timing of these events. Upstream of lin-28, the Makorin lep-2 and the lncRNA lep-5 regulate maturation cell-autonomously, indicating that distributed clocks, not a central timer, coordinate sexual differentiation of the C. elegans nervous system. Overexpression of human MKRN3 delays aspects of C. elegans sexual maturation, suggesting the conservation of Makorin function. These studies reveal roles for a Makorin and a lncRNA in timing of sexual differentiation; moreover, they demonstrate deep conservation of the lin-28-let-7 system in controlling the functional maturation of the nervous system.
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Affiliation(s)
- Hannah Lawson
- Department of BiologyUniversity of RochesterRochesterUnited States
| | - Edward Vuong
- Department of Biomedical GeneticsUniversity of RochesterRochesterUnited States
| | - Renee M Miller
- Department of Brain and Cognitive SciencesUniversity of RochesterRochesterUnited States
| | - Karin Kiontke
- Center for Developmental Genetics, Department of BiologyNew York UniversityNew YorkUnited States
| | - David HA Fitch
- Center for Developmental Genetics, Department of BiologyNew York UniversityNew YorkUnited States
| | - Douglas S Portman
- Department of BiologyUniversity of RochesterRochesterUnited States
- Department of Biomedical GeneticsUniversity of RochesterRochesterUnited States
- Department of NeuroscienceUniversity of RochesterRochesterUnited States
- DelMonte Institute for NeuroscienceUniversity of RochesterRochesterUnited States
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10
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Pereira L, Aeschimann F, Wang C, Lawson H, Serrano-Saiz E, Portman DS, Großhans H, Hobert O. Timing mechanism of sexually dimorphic nervous system differentiation. eLife 2019; 8:e42078. [PMID: 30599092 PMCID: PMC6312707 DOI: 10.7554/elife.42078] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 10/24/2018] [Indexed: 12/16/2022] Open
Abstract
The molecular mechanisms that control the timing of sexual differentiation in the brain are poorly understood. We found that the timing of sexually dimorphic differentiation of postmitotic, sex-shared neurons in the nervous system of the Caenorhabditis elegans male is controlled by the temporally regulated miRNA let-7 and its target lin-41, a translational regulator. lin-41 acts through lin-29a, an isoform of a conserved Zn finger transcription factor, expressed in a subset of sex-shared neurons only in the male. Ectopic lin-29a is sufficient to impose male-specific features at earlier stages of development and in the opposite sex. The temporal, sexual and spatial specificity of lin-29a expression is controlled intersectionally through the lin-28/let-7/lin-41 heterochronic pathway, sex chromosome configuration and neuron-type-specific terminal selector transcription factors. Two Doublesex-like transcription factors represent additional sex- and neuron-type specific targets of LIN-41 and are regulated in a similar intersectional manner.
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Affiliation(s)
- Laura Pereira
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
| | - Florian Aeschimann
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
- University of BaselBaselSwitzerland
| | - Chen Wang
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
| | - Hannah Lawson
- Department of BiologyUniversity of RochesterRochesterUnited States
| | - Esther Serrano-Saiz
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
| | - Douglas S Portman
- Department of BiologyUniversity of RochesterRochesterUnited States
- DelMonte Institute for Neuroscience, Department of Biomedical GeneticsUniversity of RochesterNew YorkUnited States
| | - Helge Großhans
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
- University of BaselBaselSwitzerland
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical InstituteColumbia UniversityNew YorkUnited States
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11
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Vidal B, Aghayeva U, Sun H, Wang C, Glenwinkel L, Bayer EA, Hobert O. An atlas of Caenorhabditis elegans chemoreceptor expression. PLoS Biol 2018; 16:e2004218. [PMID: 29293491 PMCID: PMC5749674 DOI: 10.1371/journal.pbio.2004218] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 11/22/2017] [Indexed: 12/20/2022] Open
Abstract
One goal of modern day neuroscience is the establishment of molecular maps that assign unique features to individual neuron types. Such maps provide important starting points for neuron classification, for functional analysis, and for developmental studies aimed at defining the molecular mechanisms of neuron identity acquisition and neuron identity diversification. In this resource paper, we describe a nervous system-wide map of the potential expression sites of 244 members of the largest gene family in the C. elegans genome, rhodopsin-like (class A) G-protein-coupled receptor (GPCR) chemoreceptors, using classic gfp reporter gene technology. We cover representatives of all sequence families of chemoreceptor GPCRs, some of which were previously entirely uncharacterized. Most reporters are expressed in a very restricted number of cells, often just in single cells. We assign GPCR reporter expression to all but two of the 37 sensory neuron classes of the sex-shared, core nervous system. Some sensory neurons express a very small number of receptors, while others, particularly nociceptive neurons, coexpress several dozen GPCR reporter genes. GPCR reporters are also expressed in a wide range of inter- and motorneurons, as well as non-neuronal cells, suggesting that GPCRs may constitute receptors not just for environmental signals, but also for internal cues. We observe only one notable, frequent association of coexpression patterns, namely in one nociceptive amphid (ASH) and two nociceptive phasmid sensory neurons (PHA, PHB). We identified GPCRs with sexually dimorphic expression and several GPCR reporters that are expressed in a left/right asymmetric manner. We identified a substantial degree of GPCR expression plasticity; particularly in the context of the environmentally-induced dauer diapause stage when one third of all tested GPCRs alter the cellular specificity of their expression within and outside the nervous system. Intriguingly, in a number of cases, the dauer-specific alterations of GPCR reporter expression in specific neuron classes are maintained during postdauer life and in some case new patterns are induced post-dauer, demonstrating that GPCR gene expression may serve as traits of life history. Taken together, our resource provides an entry point for functional studies and also offers a host of molecular markers for studying molecular patterning and plasticity of the nervous system.
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Affiliation(s)
- Berta Vidal
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
| | - Ulkar Aghayeva
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
| | - Haosheng Sun
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
| | - Chen Wang
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
| | - Lori Glenwinkel
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
| | - Emily A. Bayer
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, New York, United States of America
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12
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Hahnel S, Wheeler N, Lu Z, Wangwiwatsin A, McVeigh P, Maule A, Berriman M, Day T, Ribeiro P, Grevelding CG. Tissue-specific transcriptome analyses provide new insights into GPCR signalling in adult Schistosoma mansoni. PLoS Pathog 2018; 14:e1006718. [PMID: 29346437 PMCID: PMC5773224 DOI: 10.1371/journal.ppat.1006718] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Schistosomes are blood-dwelling trematodes with global impact on human and animal health. Because medical treatment is currently based on a single drug, praziquantel, there is urgent need for the development of alternative control strategies. The Schistosoma mansoni genome project provides a platform to study and connect the genetic repertoire of schistosomes to specific biological functions essential for successful parasitism. G protein-coupled receptors (GPCRs) form the largest superfamily of transmembrane receptors throughout the Eumetazoan phyla, including platyhelminths. Due to their involvement in diverse biological processes, their pharmacological importance, and proven druggability, GPCRs are promising targets for new anthelmintics. However, to identify candidate receptors, a more detailed understanding of the roles of GPCR signalling in schistosome biology is essential. An updated phylogenetic analysis of the S. mansoni GPCR genome (GPCRome) is presented, facilitated by updated genome data that allowed a more precise annotation of GPCRs. Additionally, we review the current knowledge on GPCR signalling in this parasite and provide new insights into the potential roles of GPCRs in schistosome reproduction based on the findings of a recent tissue-specific transcriptomic study in paired and unpaired S. mansoni. According to the current analysis, GPCRs contribute to gonad-specific functions but also to nongonad, pairing-dependent processes. The latter may regulate gonad-unrelated functions during the multifaceted male-female interaction. Finally, we compare the schistosome GPCRome to that of another parasitic trematode, Fasciola, and discuss the importance of GPCRs to basic and applied research. Phylogenetic analyses display GPCR diversity in free-living and parasitic platyhelminths and suggest diverse functions in schistosomes. Although their roles need to be substantiated by functional studies in the future, the data support the selection of GPCR candidates for basic and applied studies, invigorating the exploitation of this important receptor class for drug discovery against schistosomes but also other trematodes.
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Affiliation(s)
- Steffen Hahnel
- Institute of Parasitology, BFS, Justus Liebig University, Giessen, Germany
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Nic Wheeler
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, United States of America
| | - Zhigang Lu
- Institute of Parasitology, BFS, Justus Liebig University, Giessen, Germany
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Arporn Wangwiwatsin
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Paul McVeigh
- The Institute for Global Food Security, School of Biological Sciences, Queen’s University, Belfast, United Kingdom
| | - Aaron Maule
- The Institute for Global Food Security, School of Biological Sciences, Queen’s University, Belfast, United Kingdom
| | - Matthew Berriman
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Timothy Day
- Department of Biomedical Sciences, Iowa State University, Ames, Iowa, United States of America
| | - Paula Ribeiro
- Institute of Parasitology, McGill University, Montreal, Canada
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13
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Portman DS. Sexual modulation of sex-shared neurons and circuits in Caenorhabditis elegans. J Neurosci Res 2017; 95:527-538. [PMID: 27870393 DOI: 10.1002/jnr.23912] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 08/10/2016] [Accepted: 08/10/2016] [Indexed: 12/16/2022]
Abstract
Studies using the nematode C. elegans have provided unique insights into the development and function of sex differences in the nervous system. Enabled by the relative simplicity of this species, comprehensive studies have solved the complete cellular neuroanatomy of both sexes as well as the complete neural connectomes of the entire adult hermaphrodite and the adult male tail. This work, together with detailed behavioral studies, has revealed three aspects of sex differences in the nervous system: sex-specific neurons and circuits; circuits with sexually dimorphic synaptic connectivity; and sex differences in the physiology and functions of shared neurons and circuits. At all of these levels, biological sex influences neural development and function through the activity of a well-defined genetic hierarchy that acts throughout the body to translate chromosomal sex into the state of a master autosomal regulator of sexual differentiation, the transcription factor TRA-1A. This Review focuses on the role of genetic sex in implementing sex differences in shared neurons and circuits, with an emphasis on linking the sexual modulation of specific neural properties to the specification and optimization of sexually divergent and dimorphic behaviors. An important and unexpected finding from these studies is that chemosensory neurons are a primary focus of sexual modulation, with genetic sex adaptively shaping chemosensory repertoire to guide behavioral choice. Importantly, hormone-independent functions of genetic sex are the principal drivers of all of these sex differences, making nematodes an excellent model for understanding similar but poorly understood mechanisms that likely act throughout the animal kingdom. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Douglas S Portman
- Center for Neural Development and Disease, Department of Biomedical Genetics, Neuroscience, and Biology, University of Rochester Medical Center, Rochester, New York
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14
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Shirangi TR, Wong AM, Truman JW, Stern DL. Doublesex Regulates the Connectivity of a Neural Circuit Controlling Drosophila Male Courtship Song. Dev Cell 2017; 37:533-44. [PMID: 27326931 DOI: 10.1016/j.devcel.2016.05.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/06/2016] [Accepted: 05/18/2016] [Indexed: 11/26/2022]
Abstract
It is unclear how regulatory genes establish neural circuits that compose sex-specific behaviors. The Drosophila melanogaster male courtship song provides a powerful model to study this problem. Courting males vibrate a wing to sing bouts of pulses and hums, called pulse and sine song, respectively. We report the discovery of male-specific thoracic interneurons-the TN1A neurons-that are required specifically for sine song. The TN1A neurons can drive the activity of a sex-non-specific wing motoneuron, hg1, which is also required for sine song. The male-specific connection between the TN1A neurons and the hg1 motoneuron is regulated by the sexual differentiation gene doublesex. We find that doublesex is required in the TN1A neurons during development to increase the density of the TN1A arbors that interact with dendrites of the hg1 motoneuron. Our findings demonstrate how a sexual differentiation gene can build a sex-specific circuit motif by modulating neuronal arborization.
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Affiliation(s)
- Troy R Shirangi
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
| | - Allan M Wong
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - James W Truman
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - David L Stern
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
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15
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Burggren W, Souder BM, Ho DH. Metabolic rate and hypoxia tolerance are affected by group interactions and sex in the fruit fly ( Drosophila melanogaster): new data and a literature survey. Biol Open 2017; 6:471-480. [PMID: 28202465 PMCID: PMC5399560 DOI: 10.1242/bio.023994] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Population density and associated behavioral adjustments are potentially important in regulating physiological performance in many animals. In r-selected species like the fruit fly (Drosophila), where population density rapidly shifts in unpredictable and unstable environments, density-dependent physiological adjustments may aid survival of individuals living in a social environment. Yet, how population density (and associated social behaviors) affects physiological functions like metabolism is poorly understood in insects. Additionally, insects often show marked sexual dimorphism (larger females). Thus, in this study on D. melanogaster, we characterized the effects of fly density and sex on both mass-specific routine oxygen consumption (V̇O2) and hypoxia tolerance (PCrit). Females had significantly lower routine V̇O2 (∼4 µl O2 mg−1 h−1) than males (∼6 µl O2 mg−1 h−1) at an average fly density of 28 flies·respirometer chamber−1. However, V̇O2 was inversely related to fly density in males, with V̇O2 ranging from 4 to 11 µl O2 mg−1 h−1 at a density of 10 and 40 flies·chamber−1, respectively (r2=0.58, P<0.001). Female flies showed a similar but less pronounced effect, with a V̇O2 of 4 and 7 µl O2 mg−1 h−1 at a density of 10 and 40 flies·chamber−1, respectively (r2=0.43, P<0.001). PCrit (∼5.5 to 7.5 kPa) varied significantly with density in male (r2=0.50, P<0.01) but not female (r2=0.02, P>0.5) flies, with higher fly densities having a lower PCrit. An extensive survey of the literature on metabolism in fruit flies indicates that not all studies control for, or even report on, fly density and gender, both of which may affect metabolic measurements. Summary: Technical advances allowing oxygen consumption measurement in individual fruit flies actually take them out of their normal highly social context, resulting in higher oxygen consumption rates than in natural groups.
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Affiliation(s)
- Warren Burggren
- Developmental Integrative Biology Group, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - BriAnna M Souder
- Developmental Integrative Biology Group, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA
| | - Dao H Ho
- Department of Clinical Investigation, Tripler Army Medical Center, Honolulu, HI 96859, USA
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16
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Sex-specific pruning of neuronal synapses in Caenorhabditis elegans. Nature 2016; 533:206-11. [PMID: 27144354 PMCID: PMC4865429 DOI: 10.1038/nature17977] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 04/06/2016] [Indexed: 12/04/2022]
Abstract
Whether and how neurons that are present in both sexes of the same species can differentiate in a sexually dimorphic manner is not well understood. A comparison of the connectomes of the Caenorhabditis elegans hermaphrodite and male nervous systems reveals the existence of sexually dimorphic synaptic connections between neurons present in both sexes. Here, we demonstrate sex-specific functions of these sex-shared neurons and show that many neurons initially form synapses in a hybrid manner in both the male and hermaphrodite pattern before sexual maturation. Sex-specific synapse pruning then results in the sex-specific maintenance of subsets of the connections. Reversal of the sexual identity of either the pre- or postsynaptic neuron alone transforms the patterns of synaptic connectivity to that of the opposite sex. A dimorphically expressed and phylogenetically conserved transcription factor is both necessary and sufficient to determine sex-specific connectivity patterns. Our studies reveal new insights into sex-specific circuit development.
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17
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García LR, Portman DS. Neural circuits for sexually dimorphic and sexually divergent behaviors in Caenorhabditis elegans. Curr Opin Neurobiol 2016; 38:46-52. [PMID: 26929998 DOI: 10.1016/j.conb.2016.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 02/09/2016] [Indexed: 01/07/2023]
Abstract
Increasing interest in sex differences in Caenorhabditis elegans neurobiology is resulting from several advances, including the completion of the male tail connectome and the surprising discovery of two 'new' neurons in the male head. In this species, sex-specific circuits in the hermaphrodite and male control reproductive behaviors such as egg-laying and copulation, respectively. Studies of these systems are revealing interesting similarities and contrasts, particularly in the mechanisms by which nutritional status influences reproductive behaviors. Other studies have highlighted the importance of sexual modulation of shared neurons and circuits in optimizing behavioral strategies. Together, these findings indicate that C. elegans uses intertwined, distributed sex differences in circuit structure and function to implement sex-specific as well as sexually divergent, shared behaviors.
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Affiliation(s)
- L René García
- Department of Biology, Howard Hughes Medical Institute, Texas A&M University, 3258 TAMU, College Station, TX 77843-3258, United States
| | - Douglas S Portman
- Department of Biomedical Genetics and Center for Neural Development and Disease, University of Rochester, 601 Elmwood Ave., Box 645, Rochester, NY 14642, United States.
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18
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Bayless DW, Shah NM. Genetic dissection of neural circuits underlying sexually dimorphic social behaviours. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150109. [PMID: 26833830 DOI: 10.1098/rstb.2015.0109] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2015] [Indexed: 11/12/2022] Open
Abstract
The unique hormonal, genetic and epigenetic environments of males and females during development and adulthood shape the neural circuitry of the brain. These differences in neural circuitry result in sex-typical displays of social behaviours such as mating and aggression. Like other neural circuits, those underlying sex-typical social behaviours weave through complex brain regions that control a variety of diverse behaviours. For this reason, the functional dissection of neural circuits underlying sex-typical social behaviours has proved to be difficult. However, molecularly discrete neuronal subpopulations can be identified in the heterogeneous brain regions that control sex-typical social behaviours. In addition, the actions of oestrogens and androgens produce sex differences in gene expression within these brain regions, thereby highlighting the neuronal subpopulations most likely to control sexually dimorphic social behaviours. These conditions permit the implementation of innovative genetic approaches that, in mammals, are most highly advanced in the laboratory mouse. Such approaches have greatly advanced our understanding of the functional significance of sexually dimorphic neural circuits in the brain. In this review, we discuss the neural circuitry of sex-typical social behaviours in mice while highlighting the genetic technical innovations that have advanced the field.
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Affiliation(s)
- Daniel W Bayless
- Department of Anatomy, University of California San Francisco, San Francisco, CA 94158, USA
| | - Nirao M Shah
- Department of Anatomy, University of California San Francisco, San Francisco, CA 94158, USA
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19
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Tan AWL, Francischetti IMB, Slovak M, Kini RM, Ribeiro JMC. Sexual differences in the sialomes of the zebra tick, Rhipicephalus pulchellus. J Proteomics 2015; 117:120-44. [PMID: 25576852 PMCID: PMC4374903 DOI: 10.1016/j.jprot.2014.12.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/18/2014] [Accepted: 12/30/2014] [Indexed: 11/29/2022]
Abstract
Ticks rely exclusively on vertebrate blood for their survival. During feeding ticks inject into their hosts a sophisticated salivary potion that overcomes host hemostasis and adverse inflammatory responses. These mediators may also enhance pathogen transmission. Knowledge of the tick salivary protein repertoire may lead to vaccine targets to disrupt feeding and/or parasite transmission as well as to the discovery of novel pharmacological agents. Male saliva may also assist reproduction because males use their mouthparts to lubricate and introduce their spermatophores into the females' genital pore. The analyses of the sialomes of male and female ticks independently allow us to understand the strategy used by each gender to feed successfully. We sequenced cDNA libraries from pools of salivary glands from adult male and female Rhipicephalus pulchellus feeding at different time points, using the Illumina HiSeq protocol. De novo assembly of a total of 241,229,128 paired-end reads lead to extraction of 50,460 coding sequences (CDS), 11,277 of which had more than 75% coverage to known transcripts, or represented novel sequences, and were submitted to GenBank. Additionally, we generated the proteome, from the salivary gland extracts of male and female R. pulchellus, yielding a total of 454 and 2063 proteins respectively which were identified by one or more peptides with at least 95% confidence. The data set is presented as an annotated hyperlinked Excel spreadsheet, describing 121 putative secreted protein families. Female and male specific transcripts were identified. BIOLOGICAL SIGNIFICANCE This annotated R. pulchellus database represents a mining field for future experiments involving the resolution of time-dependent transcript expression in this tick species, as well as to define novel vaccine targets and discover novel pharmaceuticals. Gender specific proteins may represent different repertoires of pharmacological reagents to assist feeding by each sex, and in males may represent proteins that assist reproduction similarly to seminal proteins in other animals.
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Affiliation(s)
- Angelina W L Tan
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore; Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore.
| | - Ivo M B Francischetti
- Vector Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville MD 20852, USA.
| | - Mirko Slovak
- Institute of Zoology, Slovak Academy of Sciences, 842 06 Bratislava, Slovakia.
| | - R Manjunatha Kini
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore; Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore; Department of Biochemistry and Molecular Biology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298-0614, USA; University of South Australia, School of Pharmacy and Medical Sciences, Adelaide, South Australia 5001, Australia.
| | - José M C Ribeiro
- Vector Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville MD 20852, USA.
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20
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Kalis AK, Kissiov DU, Kolenbrander ES, Palchick Z, Raghavan S, Tetreault BJ, Williams E, Loer CM, Wolff JR. Patterning of sexually dimorphic neurogenesis in the caenorhabditis elegans ventral cord by Hox and TALE homeodomain transcription factors. Dev Dyn 2014; 243:159-71. [PMID: 24115648 DOI: 10.1002/dvdy.24064] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 09/16/2013] [Accepted: 09/16/2013] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Reproduction in animals requires development of distinct neurons in each sex. In C. elegans, most ventral cord neurons (VCNs) are present in both sexes, with the exception of six hermaphrodite-specific neurons (VCs) and nine pairs of male-specific neurons (CAs and CPs) that arise from analogous precursor cells. How are the activities of sexual regulators and mediators of neuronal survival, division, and fate coordinated to generate sex-specificity in VCNs? RESULTS To address this, we have developed a toolkit of VCN markers that allows us to examine sex-specific neurogenesis, asymmetric fates of daughters of a neuroblast division, and regional specification on the anteroposterior axis. Here, we describe the roles of the Hox transcription factors LIN-39 and MAB-5 in promoting survival, differentiation, and regionalization of VCNs. We also find that the TALE class homeodomain proteins CEH-20 and UNC-62 contribute to specification of neurotransmitter fate in males. Furthermore, we identify that VCN sex is determined during the L1 larval stage. CONCLUSIONS These findings, combined with future analyses made possible by the suite of VCN markers described here, will elucidate how Hox-mediated cell fate decisions and sex determination intersect to influence development of neuronal sex differences.
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21
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Emmons SW. The development of sexual dimorphism: studies of the Caenorhabditis elegans male. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2014; 3:239-62. [PMID: 25262817 PMCID: PMC4181595 DOI: 10.1002/wdev.136] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 04/02/2014] [Indexed: 01/09/2023]
Abstract
Studies of the development of the Caenorhabditis elegans male have been carried out with the aim of understanding the basis of sexual dimorphism. Postembryonic development of the two C. elegans sexes differs extensively. Development along either the hermaphrodite or male pathway is specified initially by the X to autosome ratio. The regulatory events initiated by this ratio include a male-determining paracrine intercellular signal. Expression of this signal leads to different consequences in three regions of the body: the nongonadal soma, the somatic parts of the gonad, and the germ line. In the nongonadal soma, activity of the key Zn-finger transcription factor TRA-1 determines hermaphrodite development; in its absence, the male pathway is followed. Only a few genes directly regulated by TRA-1 are currently known, including members of the evolutionarily conserved, male-determining DM domain Zn-finger transcription factors. In the somatic parts of the gonad and germ line, absence of TRA-1 activity is not sufficient for full expression of the male pathway. Several additional transcription factors involved have been identified. In the germ line, regulatory genes for sperm development that act at the level of RNA in the cytoplasm play a prominent role.
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Affiliation(s)
- Scott W. Emmons
- Albert Einstein College of Medicine 1300 Morris Park Ave. Bronx, New York 10461
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22
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Fagan KA, Portman DS. Sexual modulation of neural circuits and behavior in Caenorhabditis elegans. Semin Cell Dev Biol 2014; 33:3-9. [PMID: 24937129 DOI: 10.1016/j.semcdb.2014.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 06/05/2014] [Accepted: 06/09/2014] [Indexed: 01/07/2023]
Abstract
Sex differences in behavior-both sex-specific and shared behaviors-are fundamental to nearly all animal species. One often overlooked mechanism by which these behavioral differences can be generated is through sex-specific modulation of shared circuitry (i.e., circuits present in both sexes). In vertebrates this modulation is likely regulated by hormone-dependent mechanisms as well as by somatic sex itself; invertebrate models have particular promise for understanding the latter of these. Here we review molecular and behavioral evidence of sexual modulation of shared circuitry in the nematode Caenorhabditis elegans. Multiple behaviors in this species, both copulatory and not, are modulated by the genetic sex of shared neurons and circuit. These studies are close to uncovering the molecular mechanisms by which somatic sex modulates neural function in the worm, mechanisms which may be well conserved in more complex organisms. Improving our understanding of the modulation of neural circuit development and function by somatic sex may lend important insight into sex differences in the mammalian nervous system which, in turn, may have important implications for sex biases in disease.
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Affiliation(s)
- Kelli A Fagan
- Neuroscience Graduate Program, University of Rochester, Rochester, NY 14642, United States; Center for Neural Development and Disease and Department of Biomedical Genetics, University of Rochester, Rochester, NY 14642, United States
| | - Douglas S Portman
- Center for Neural Development and Disease and Department of Biomedical Genetics, University of Rochester, Rochester, NY 14642, United States; Department of Biomedical Genetics, University of Rochester, Rochester, NY 14642, United States.
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23
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Abstract
Sexually dimorphic behaviors, qualitative or quantitative differences in behaviors between the sexes, result from the activity of a sexually differentiated nervous system. Sensory cues and sex hormones control the entire repertoire of sexually dimorphic behaviors, including those commonly thought to be charged with emotion such as courtship and aggression. Such overarching control mechanisms regulate distinct genes and neurons that in turn specify the display of these behaviors in a modular manner. How such modular control is transformed into cohesive internal states that correspond to sexually dimorphic behavior is poorly understood. We summarize current understanding of the neural circuit control of sexually dimorphic behaviors from several perspectives, including how neural circuits in general, and sexually dimorphic neurons in particular, can generate sexually dimorphic behaviors, and how molecular mechanisms and evolutionary constraints shape these behaviors. We propose that emergent themes such as the modular genetic and neural control of dimorphic behavior are broadly applicable to the neural control of other behaviors.
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Affiliation(s)
- Cindy F Yang
- Program in Neuroscience, University of California San Francisco, MC2722, San Francisco, CA 94158, USA; Department of Anatomy, University of California San Francisco, MC2722, San Francisco, CA 94158, USA
| | - Nirao M Shah
- Department of Anatomy, University of California San Francisco, MC2722, San Francisco, CA 94158, USA.
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24
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Mowrey WR, Bennett JR, Portman DS. Distributed effects of biological sex define sex-typical motor behavior in Caenorhabditis elegans. J Neurosci 2014; 34:1579-91. [PMID: 24478342 PMCID: PMC3905135 DOI: 10.1523/jneurosci.4352-13.2014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 11/05/2013] [Accepted: 11/07/2013] [Indexed: 12/24/2022] Open
Abstract
Sex differences in shared behaviors (for example, locomotion and feeding) are a nearly universal feature of animal biology. Though these behaviors may share underlying neural programs, their kinematics can exhibit robust differences between males and females. The neural underpinnings of these differences are poorly understood because of the often-untested assumption that they are determined by sex-specific body morphology. Here, we address this issue in the nematode Caenorhabditis elegans, which features two sexes with distinct body morphologies but similar locomotor circuitry and body muscle. Quantitative behavioral analysis shows that C. elegans and related nematodes exhibit significant sex differences in the dynamics and geometry of locomotor body waves, such that the male is generally faster. Using a recently proposed model of locomotor wave propagation, we show that sex differences in both body mechanics and the intrinsic dynamics of the motor system can contribute to kinematic differences in distinct mechanical contexts. By genetically sex-reversing the properties of specific tissues and cells, however, we find that sex-specific locomotor frequency in C. elegans is determined primarily by the functional modification of shared sensory neurons. Further, we find that sexual modification of body wall muscle together with the nervous system is required to alter body wave speed. Thus, rather than relying on a single focus of modification, sex differences in motor dynamics require independent modifications to multiple tissue types. Our results suggest shared motor behaviors may be sex-specifically optimized though distributed modifications to several aspects of morphology and physiology.
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Affiliation(s)
| | | | - Douglas S. Portman
- Center for Neural Development and Disease
- Department of Biomedical Genetics, and
- Department of Biology, University of Rochester, School of Medicine and Dentistry, Rochester, New York 14642
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25
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Chong T, Collins JJ, Brubacher JL, Zarkower D, Newmark PA. A sex-specific transcription factor controls male identity in a simultaneous hermaphrodite. Nat Commun 2013; 4:1814. [PMID: 23652002 PMCID: PMC3674237 DOI: 10.1038/ncomms2811] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 03/26/2013] [Indexed: 12/26/2022] Open
Abstract
Evolutionary transitions between hermaphroditic and dioecious reproductive states are found in many groups of animals. To understand such transitions, it is important to characterize diverse modes of sex determination utilized by metazoans. Currently, little is known about how simultaneous hermaphrodites specify and maintain male and female organs in a single individual. Here we show that a sex-specific gene, Smed-dmd-1 encoding a predicted doublesex/male-abnormal-3 (DM) domain transcription factor, is required for specification of male germ cells in a simultaneous hermaphrodite, the planarian Schmidtea mediterranea. dmd-1 has a male-specific role in the maintenance and regeneration of the testes and male accessory reproductive organs. In addition, a homologue of dmd-1 exhibits male-specific expression in Schistosoma mansoni, a derived, dioecious flatworm. These results demonstrate conservation of the role of DM domain genes in sexual development in lophotrochozoans and suggest one means by which modulation of sex-specific pathways can drive the transition from hermaphroditism to dioecy. Hermaphrodites develop and maintain male and female reproductive organs in a single individual. Chong et al. show that a DM domain transcription factor is required for male germ cell regeneration and maintains ‘maleness’ in a hermaphrodite, the planarian flatworm Schmidtea mediterranea.
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Affiliation(s)
- Tracy Chong
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601 South Goodwin Avenue, Urbana, Illinois 61801, USA
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26
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Sakai N, Iwata R, Yokoi S, Butcher RA, Clardy J, Tomioka M, Iino Y. A sexually conditioned switch of chemosensory behavior in C. elegans. PLoS One 2013; 8:e68676. [PMID: 23861933 PMCID: PMC3701651 DOI: 10.1371/journal.pone.0068676] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 06/06/2013] [Indexed: 11/18/2022] Open
Abstract
In sexually reproducing animals, mating is essential for transmitting genetic information to the next generation and therefore animals have evolved mechanisms for optimizing the chance of successful mate location. In the soil nematode C. elegans, males approach hermaphrodites via the ascaroside pheromones, recognize hermaphrodites when their tails contact the hermaphrodites' body, and eventually mate with them. These processes are mediated by sensory signals specialized for sexual communication, but other mechanisms may also be used to optimize mate location. Here we describe associative learning whereby males use sodium chloride as a cue for hermaphrodite location. Both males and hermaphrodites normally avoid sodium chloride after associative conditioning with salt and starvation. However, we found that males become attracted to sodium chloride after conditioning with salt and starvation if hermaphrodites are present during conditioning. For this conditioning, which we call sexual conditioning, hermaphrodites are detected by males through pheromonal signaling and additional cue(s). Sex transformation experiments suggest that neuronal sex of males is essential for sexual conditioning. Altogether, these results suggest that C. elegans males integrate environmental, internal and social signals to determine the optimal strategy for mate location.
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Affiliation(s)
- Naoko Sakai
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Ryo Iwata
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Saori Yokoi
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Rebecca A. Butcher
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jon Clardy
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Masahiro Tomioka
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Yuichi Iino
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- * E-mail:
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27
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PDF-1 neuropeptide signaling modulates a neural circuit for mate-searching behavior in C. elegans. Nat Neurosci 2012; 15:1675-82. [PMID: 23143519 PMCID: PMC3509246 DOI: 10.1038/nn.3253] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 10/01/2012] [Indexed: 12/20/2022]
Abstract
Appetitive behaviors require complex decision-making, involving the integration of environmental stimuli and physiological needs. C. elegans mate searching is a male-specific exploratory behavior regulated by two competing needs: food versus reproductive appetite. Here we show that the Pigment Dispersing Factor Receptor (PDFR-1) modulates the circuit that encodes the male reproductive drive promoting male exploration upon mate-deprivation. PDFR-1 and its ligand PDF-1 stimulate mate searching in the male but not in the hermaphrodite. pdf-1 is required in the gender-shared interneuron AIM and the receptor acts in internal and external environment-sensing neurons of the shared nervous system (URY, PQR and PHA) to produce mate-searching behavior. Thus, the pdf-1/pdfr-1 pathway functions in non sex-specific neurons to produce a male-specific, goal-oriented exploratory behavior. Our results indicate that secretin neuropeptidergic signaling plays an ancient role in regulating motivational internal states.
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28
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Miersch C, Döring F. Sex differences in carbohydrate metabolism are linked to gene expression in Caenorhabditis elegans. PLoS One 2012; 7:e44748. [PMID: 22984551 PMCID: PMC3439400 DOI: 10.1371/journal.pone.0044748] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 08/06/2012] [Indexed: 11/18/2022] Open
Abstract
The male and the hermaphrodite forms of the nematode Caenorhabditis elegans (C. elegans) differ markedly in anatomy, nervous system and behavior at adulthood. Using the male mutants fog-2, him-5, and him-8, we compared body proportions and composition, and aspects of carbohydrate metabolism and gene expression between the C. elegans sexes in three adult stages. In all experiments, both sexes were grown on the same plate and separated using flow cytometry. The fat to fat-free mass ratio and the body volume-adjusted fat mass is similar between the sexes, although the body size is more than 50% smaller in adult males than in age-matched hermaphrodites. The volume-adjusted total RNA content is approximately 2-fold lower in males. Biochemical and NMR-based analyses reveal higher trehalose levels and much lower glucose levels in males than in hermaphrodites. The resulting trehalose-to-glucose ratio is 5.4-fold higher in males. These sex differences are reflected in gene expression data because the genes encoding key enzymes of the glycolysis and trehalose synthesis pathways are more highly expressed in males than in hermaphrodites. Notably, expression of the phosphofructokinase gene (C50F4.2) is 29-fold higher in males. Comparative analysis of gene expression data identifies 285 male-specific and 160 hermaphrodite-specific genes. These include transcription factor and C-type lectin-encoding genes. More than 35% of all C-type lectin genes are more highly expressed in males. The expression of many C-type lectin genes differs by a factor of >100 between the sexes. In conclusion, we found sex differences in carbohydrate metabolism that are linked to gene expression and identified certain lectin genes that are differentially expressed by the C. elegans sexes.
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Affiliation(s)
- Claudia Miersch
- Department of Molecular Prevention, Institute of Human Nutrition and Food Science, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Frank Döring
- Department of Molecular Prevention, Institute of Human Nutrition and Food Science, Christian-Albrechts-University of Kiel, Kiel, Germany
- * E-mail:
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Choi YJ, Ghedin E, Berriman M, McQuillan J, Holroyd N, Mayhew GF, Christensen BM, Michalski ML. A deep sequencing approach to comparatively analyze the transcriptome of lifecycle stages of the filarial worm, Brugia malayi. PLoS Negl Trop Dis 2011; 5:e1409. [PMID: 22180794 PMCID: PMC3236722 DOI: 10.1371/journal.pntd.0001409] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 10/19/2011] [Indexed: 11/19/2022] Open
Abstract
Background Developing intervention strategies for the control of parasitic nematodes continues to be a significant challenge. Genomic and post-genomic approaches play an increasingly important role for providing fundamental molecular information about these parasites, thus enhancing basic as well as translational research. Here we report a comprehensive genome-wide survey of the developmental transcriptome of the human filarial parasite Brugia malayi. Methodology/Principal Findings Using deep sequencing, we profiled the transcriptome of eggs and embryos, immature (≤3 days of age) and mature microfilariae (MF), third- and fourth-stage larvae (L3 and L4), and adult male and female worms. Comparative analysis across these stages provided a detailed overview of the molecular repertoires that define and differentiate distinct lifecycle stages of the parasite. Genome-wide assessment of the overall transcriptional variability indicated that the cuticle collagen family and those implicated in molting exhibit noticeably dynamic stage-dependent patterns. Of particular interest was the identification of genes displaying sex-biased or germline-enriched profiles due to their potential involvement in reproductive processes. The study also revealed discrete transcriptional changes during larval development, namely those accompanying the maturation of MF and the L3 to L4 transition that are vital in establishing successful infection in mosquito vectors and vertebrate hosts, respectively. Conclusions/Significance Characterization of the transcriptional program of the parasite's lifecycle is an important step toward understanding the developmental processes required for the infectious cycle. We find that the transcriptional program has a number of stage-specific pathways activated during worm development. In addition to advancing our understanding of transcriptome dynamics, these data will aid in the study of genome structure and organization by facilitating the identification of novel transcribed elements and splice variants. Lymphatic filariasis, also known as elephantiasis, is a tropical disease affecting over 120 million people worldwide. More than 40 million people live with painful, disfiguring symptoms that can cause severe debilitation and social stigma. The disease is caused by infection with thread-like filarial nematodes (roundworms) that have a complex parasitic lifecycle involving both human and mosquito hosts. In the study, the authors profiled the transcriptome (the set of genes transcribed into messenger RNA rather than all of those in the genome) of the human filarial worm Brugia malayi in different lifecyle stages using deep sequencing technology. The analysis revealed major transitions in RNA expression from eggs through larval stages to adults. Using statistical approaches, the authors identified groups of genes with distinct life stage dependent transcriptional patterns, with particular emphasis on genes displaying sex-biased or germline-enriched patterns and those displaying significant changes during larval development. This study presents a first comprehensive analysis of the lifecycle transcriptome of B. malayi, providing fundamental molecular information that should help researchers better understand parasite biology and could provide clues for the development of more effective interventions.
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Affiliation(s)
- Young-Jun Choi
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Elodie Ghedin
- Department of Computational and Systems Biology, Center for Vaccine Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Matthew Berriman
- The Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Jacqueline McQuillan
- The Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Nancy Holroyd
- The Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - George F. Mayhew
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Bruce M. Christensen
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Michelle L. Michalski
- Department of Biology and Microbiology, University of Wisconsin Oshkosh, Oshkosh, Wisconsin, United States of America
- * E-mail:
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Siehr MS, Koo PK, Sherlekar AL, Bian X, Bunkers MR, Miller RM, Portman DS, Lints R. Multiple doublesex-related genes specify critical cell fates in a C. elegans male neural circuit. PLoS One 2011; 6:e26811. [PMID: 22069471 PMCID: PMC3206049 DOI: 10.1371/journal.pone.0026811] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 10/04/2011] [Indexed: 11/18/2022] Open
Abstract
Background In most animal species, males and females exhibit differences in behavior and morphology that relate to their respective roles in reproduction. DM (Doublesex/MAB-3) domain transcription factors are phylogenetically conserved regulators of sexual development. They are thought to establish sexual traits by sex-specifically modifying the activity of general developmental programs. However, there are few examples where the details of these interactions are known, particularly in the nervous system. Methodology/Principal Findings In this study, we show that two C. elegans DM domain genes, dmd-3 and mab-23, regulate sensory and muscle cell development in a male neural circuit required for mating. Using genetic approaches, we show that in the circuit sensory neurons, dmd-3 and mab-23 establish the correct pattern of dopaminergic (DA) and cholinergic (ACh) fate. We find that the ETS-domain transcription factor gene ast-1, a non-sex-specific, phylogenetically conserved activator of dopamine biosynthesis gene transcription, is broadly expressed in the circuit sensory neuron population. However, dmd-3 and mab-23 repress its activity in most cells, promoting ACh fate instead. A subset of neurons, preferentially exposed to a TGF-beta ligand, escape this repression because signal transduction pathway activity in these cells blocks dmd-3/mab-23 function, allowing DA fate to be established. Through optogenetic and pharmacological approaches, we show that the sensory and muscle cell characteristics controlled by dmd-3 and mab-23 are crucial for circuit function. Conclusions/Significance In the C. elegans male, DM domain genes dmd-3 and mab-23 regulate expression of cell sub-type characteristics that are critical for mating success. In particular, these factors limit the number of DA neurons in the male nervous system by sex-specifically regulating a phylogenetically conserved dopamine biosynthesis gene transcription factor. Homologous interactions between vertebrate counterparts could regulate sex differences in neuron sub-type populations in the brain.
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Affiliation(s)
- Meagan S. Siehr
- Department of Biology, Texas A & M University, College Station, Texas, United States of America
| | - Pamela K. Koo
- Department of Biology, Texas A & M University, College Station, Texas, United States of America
| | - Amrita L. Sherlekar
- Department of Biology, Texas A & M University, College Station, Texas, United States of America
| | - Xuelin Bian
- Department of Biology, Texas A & M University, College Station, Texas, United States of America
| | - Meredith R. Bunkers
- Department of Biology, Texas A & M University, College Station, Texas, United States of America
| | - Renee M. Miller
- Department of Biomedical Genetics, Center for Neural Development and Disease, University of Rochester, Rochester, New York, United States of America
| | - Douglas S. Portman
- Department of Biomedical Genetics, Center for Neural Development and Disease, University of Rochester, Rochester, New York, United States of America
| | - Robyn Lints
- Department of Biology, Texas A & M University, College Station, Texas, United States of America
- * E-mail:
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Meissner GW, Manoli DS, Chavez JF, Knapp JM, Lin TL, Stevens RJ, Mellert DJ, Tran DH, Baker BS. Functional dissection of the neural substrates for sexual behaviors in Drosophila melanogaster. Genetics 2011; 189:195-211. [PMID: 21705753 PMCID: PMC3176112 DOI: 10.1534/genetics.111.129940] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 06/13/2011] [Indexed: 11/18/2022] Open
Abstract
The male-specific Fruitless proteins (FruM) act to establish the potential for male courtship behavior in Drosophila melanogaster and are expressed in small groups of neurons throughout the nervous system. We screened ∼1000 GAL4 lines, using assays for general courtship, male-male interactions, and male fertility to determine the phenotypes resulting from the GAL4-driven inhibition of FruM expression in subsets of these neurons. A battery of secondary assays showed that the phenotypic classes of GAL4 lines could be divided into subgroups on the basis of additional neurobiological and behavioral criteria. For example, in some lines, restoration of FruM expression in cholinergic neurons restores fertility or reduces male-male courtship. Persistent chains of males courting each other in some lines results from males courting both sexes indiscriminately, whereas in other lines this phenotype results from apparent habituation deficits. Inhibition of ectopic FruM expression in females, in populations of neurons where FruM is necessary for male fertility, can rescue female infertility. To identify the neurons responsible for some of the observed behavioral alterations, we determined the overlap between the identified GAL4 lines and endogenous FruM expression in lines with fertility defects. The GAL4 lines causing fertility defects generally had widespread overlap with FruM expression in many regions of the nervous system, suggesting likely redundant FruM-expressing neuronal pathways capable of conferring male fertility. From associations between the screened behaviors, we propose a functional model for courtship initiation.
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Affiliation(s)
- Geoffrey W. Meissner
- Neurosciences Program, and
- Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, Virginia 20147
| | | | - Jose F. Chavez
- Department of Biology, Stanford University, Stanford, California 94305
| | - Jon-Michael Knapp
- Neurosciences Program, and
- Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, Virginia 20147
| | - Tasha L. Lin
- Department of Biology, Stanford University, Stanford, California 94305
| | - Robin J. Stevens
- Department of Biology, Stanford University, Stanford, California 94305
| | - David J. Mellert
- Department of Biology, Stanford University, Stanford, California 94305
- Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, Virginia 20147
| | - David H. Tran
- Department of Biology, Stanford University, Stanford, California 94305
| | - Bruce S. Baker
- Neurosciences Program, and
- Department of Biology, Stanford University, Stanford, California 94305
- Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, Virginia 20147
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32
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Wu MV, Shah NM. Control of masculinization of the brain and behavior. Curr Opin Neurobiol 2010; 21:116-23. [PMID: 20970320 DOI: 10.1016/j.conb.2010.09.014] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 09/27/2010] [Indexed: 02/05/2023]
Abstract
Sex steroid hormones exert a profound influence on the sexual differentiation and function of the neural circuits that mediate dimorphic behaviors. Both estrogen and testosterone are essential for male typical behaviors in many species. Recent studies with genetically modified mice provide important new insights into the logic whereby these two hormones coordinate the display of sexually dimorphic behaviors: estrogen sets up the masculine repertoire of sexual and territorial behaviors and testosterone controls the extent of these male displays.
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Affiliation(s)
- Melody V Wu
- Program in Neuroscience, University of California, San Francisco, MC2722, San Francisco, CA 94158, USA
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Cell death and sexual differentiation of behavior: worms, flies, and mammals. Curr Opin Neurobiol 2010; 20:776-83. [PMID: 20934320 DOI: 10.1016/j.conb.2010.09.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 09/08/2010] [Accepted: 09/09/2010] [Indexed: 11/24/2022]
Abstract
Sex differences in the nervous system are found throughout the animal kingdom. Here, we discuss three prominent genetic models: nematodes, fruit flies, and mice. In all three, differential cell death is central to sexual differentiation and shared molecular mechanisms have been identified. Our knowledge of the precise function of neural sex differences lags behind. One fruitful approach to the 'function' question is to contrast sexual differentiation in standard laboratory animals with differentiation in species exhibiting unique social and reproductive organizations. Advanced genetic strategies are also addressing this question in worms and flies, and may soon be applicable to vertebrates.
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Kleemann G, Jia L, Emmons SW. Regulation of Caenorhabditis elegans male mate searching behavior by the nuclear receptor DAF-12. Genetics 2008; 180:2111-22. [PMID: 18854588 PMCID: PMC2600945 DOI: 10.1534/genetics.108.093773] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 10/11/2008] [Indexed: 12/19/2022] Open
Abstract
Coordination of animal behavior with reproductive status is often achieved through elaboration of hormones by the gonad. In the nematode Caenorhabditis elegans, adult males explore their environment to locate mates. Mate searching is regulated by presence of mates, nutritional status, and a signal from the gonad. Here we show that the gonadal signal acts via the nuclear receptor DAF-12, a protein known to regulate several C. elegans life-history traits. DAF-12 has both activational and organizational functions to stimulate exploratory behavior and acts downstream of the gonadal signal, outside of the gonad. DAF-12 acts upstream of sensory input from mating partners and physiological signals indicating nutritional status. Mate searching was rescued in germ-line ablated animals, but not if both germ line and somatic gonad were ablated, by a precursor of the DAF-12 ligand, dafachronic acid (DA). The results are interpreted to suggest that the germ line produces a DA precursor that is converted to DA outside of the germ line, possibly in the somatic gonad. As it does in other pathways in which it functions, in regulation of male mate searching behavior DAF-12 acts at a choice point between alternatives favoring reproduction (mate searching) vs. survival (remaining on food).
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Affiliation(s)
- Gunnar Kleemann
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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35
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Lee K, Portman DS. Neural Sex Modifies the Function of a C. elegans Sensory Circuit. Curr Biol 2007; 17:1858-63. [DOI: 10.1016/j.cub.2007.10.015] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 09/28/2007] [Accepted: 10/01/2007] [Indexed: 11/16/2022]
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