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Zhu B, Jin P, Hou Z, Li J, Wei S, Li S. Chromosomal-level genome of a sheet-web spider provides insight into the composition and evolution of venom. Mol Ecol Resour 2022; 22:2333-2348. [PMID: 35182027 DOI: 10.1111/1755-0998.13601] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 02/07/2022] [Accepted: 02/14/2022] [Indexed: 11/29/2022]
Abstract
Spiders are the most abundant venomous predators in the world. Previous research related to spider venom has mostly relied on transcriptomes and proteomes, with only a few high-quality genomes available. This is far from consistent with the species diversity of spiders. In this study, we constructed a high-quality chromosome-level genome assembly of Hylyphantes graminicola, which contained 13 chromosomes, with a genome length of 931.68 Mb and scaffold N50 of 77.07 Mb. Integrating genome, transcriptome, and proteome profiling, we identified a total of 59 coding genes among nine toxin gene families. Among them, Group 7 allergen (ALL7) protein was reported in spider venom for the first time. Its coding genes had a predicted signal peptide and maintained high expression levels in the venom, suggesting that ALL7 plays an important role in venom and maybe is a type of newly discovered venom toxin in the spider. By implementing comparative genomics, we found a similar gene number of main toxin gene families in spiders and the scorpion genome with conservative evolutionary rates, indicating that these toxin genes could be an ancient (~400 million years) and a conserved "basic toolkit" for spiders and scorpions to perform primary defense functions. Obtaining high-quality chromosome-level genomes from spiders not only facilitates venom research and toxin resource application, but also can improve comparative genomic analysis in other important traits, like the evolution of silk or behavior.
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Affiliation(s)
- Bingyue Zhu
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Pengyu Jin
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhonge Hou
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jianlong Li
- Guangdong Provincial Key Laboratory of Tea Plant Resources Innovation and Utilization/ Tea Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China
| | - Shujun Wei
- Institute of Plant and Environmental Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China
| | - Shuqiang Li
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
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2
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Evidence for Stabilizing Selection Driving Mutational Turnover of Short Motifs in the Eukaryotic Complementary Sex Determiner (Csd) Protein. G3-GENES GENOMES GENETICS 2018; 8:3803-3812. [PMID: 30287489 PMCID: PMC6288827 DOI: 10.1534/g3.118.200527] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Short linear motifs (SLiMs) can play pivotal functional roles in proteins, such as targeting proteins to specific subcellular localizations, modulating the efficiency of translation and tagging proteins for degradation. Until recently we had little knowledge about SLiM evolution. Only a few amino acids in these motifs are functionally important, making them likely to evolve ex nihilo and suggesting that they can play key roles in protein evolution. Several reports now suggest that these motifs can appear and disappear while their function in the protein is preserved, a process sometimes referred to as “turnover”. However, there has been a lack of specific experiments to determine whether independently evolved motifs do indeed have the same function, which would conclusively determine whether the process of turnover actually occurs. In this study, we experimentally detected evidence for such a mutational turnover process for nuclear localization signals (NLS) during the post-duplication divergence of the Complementary sex determiner (Csd) and Feminizer (Fem) proteins in the honeybee (Apis mellifera) lineage. Experiments on the nuclear transport activity of protein segments and those of the most recent common ancestor (MRCA) sequences revealed that three new NLS motifs evolved in the Csd protein during the post-duplication divergence while other NLS motifs were lost that existed before duplication. A screen for essential and newly evolved amino acids revealed that new motifs in the Csd protein evolved by one or two missense mutations coding for lysine. Amino acids that were predating the duplication were also essential in the acquisition of the C1 motif suggesting that the ex nihilo origin was constrained by preexisting amino acids in the physical proximity. Our data support a model in which stabilizing selection maintains the constancy of nuclear transport function but allowed mutational turnover of the encoding NLS motifs.
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3
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Zareba J, Blazej P, Laszkiewicz A, Sniezewski L, Majkowski M, Janik S, Cebrat M. Uneven distribution of complementary sex determiner (csd) alleles in Apis mellifera population. Sci Rep 2017; 7:2317. [PMID: 28539589 PMCID: PMC5443781 DOI: 10.1038/s41598-017-02629-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 04/04/2017] [Indexed: 11/23/2022] Open
Abstract
The complementary sex determiner (csd) gene determines the sex of the western honey bee (Apis mellifera L.). Bees that are heterozygous at the csd locus develop into females; whereas hemizygous bees develop into males. The co-occurrence of two identical csd alleles in a single diploid genome leads to the genetic death of the bee. Thus, the maintenance of csd diversity in the population is favoured. The number and distribution of csd alleles is particularly interesting in light of the recent decline in the honey bee population. In this study, we analysed the distribution of csd alleles in two Polish populations separated by about 100 km. We analysed the maternal alleles of 193 colonies and found 121 different alleles. We also analysed the distribution and frequency of the alleles, and found that they are distributed unevenly. We show that the methods that have been used so far to estimate the total worldwide number of csd alleles have significantly underestimated their diversity. We also show that the uneven distribution of csd alleles is caused by a large number of infrequent alleles, which most likely results from the fact that these alleles are generated very frequently.
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Affiliation(s)
- Joanna Zareba
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wroclaw, Poland
| | - Pawel Blazej
- Department of Genomics, Faculty of Biotechnology, Wroclaw University, F. Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Agnieszka Laszkiewicz
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wroclaw, Poland
| | - Lukasz Sniezewski
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wroclaw, Poland
| | - Michal Majkowski
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wroclaw, Poland
| | - Sylwia Janik
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wroclaw, Poland
| | - Malgorzata Cebrat
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wroclaw, Poland.
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4
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Kaskinova MD, Nikolenko AG. csd gene of honeybee: Genetic structure, functioning, and evolution. RUSS J GENET+ 2017. [DOI: 10.1134/s1022795417010070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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5
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Gan X, Hay A, Kwantes M, Haberer G, Hallab A, Ioio RD, Hofhuis H, Pieper B, Cartolano M, Neumann U, Nikolov LA, Song B, Hajheidari M, Briskine R, Kougioumoutzi E, Vlad D, Broholm S, Hein J, Meksem K, Lightfoot D, Shimizu KK, Shimizu-Inatsugi R, Imprialou M, Kudrna D, Wing R, Sato S, Huijser P, Filatov D, Mayer KFX, Mott R, Tsiantis M. The Cardamine hirsuta genome offers insight into the evolution of morphological diversity. NATURE PLANTS 2016; 2:16167. [PMID: 27797353 PMCID: PMC8826541 DOI: 10.1038/nplants.2016.167] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 09/30/2016] [Indexed: 05/18/2023]
Abstract
Finding causal relationships between genotypic and phenotypic variation is a key focus of evolutionary biology, human genetics and plant breeding. To identify genome-wide patterns underlying trait diversity, we assembled a high-quality reference genome of Cardamine hirsuta, a close relative of the model plant Arabidopsis thaliana. We combined comparative genome and transcriptome analyses with the experimental tools available in C. hirsuta to investigate gene function and phenotypic diversification. Our findings highlight the prevalent role of transcription factors and tandem gene duplications in morphological evolution. We identified a specific role for the transcriptional regulators PLETHORA5/7 in shaping leaf diversity and link tandem gene duplication with differential gene expression in the explosive seed pod of C. hirsuta. Our work highlights the value of comparative approaches in genetically tractable species to understand the genetic basis for evolutionary change.
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Affiliation(s)
- Xiangchao Gan
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Angela Hay
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Michiel Kwantes
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Georg Haberer
- Plant Genome and Systems Biology, Helmholtz Zentrum Munich, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Asis Hallab
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Raffaele Dello Ioio
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
- Present Address: †Present address: Department of Biology and Biotechnology, Università La Sapienza, P.le Aldo Moro, 5, 00185 Rome, Italy (R.D.I.). The Global Food Security, BBSRC, Polaris House, North Star Avenue, Swindon SN2 1UH, UK (E.K.). Institute of Biotechnology, Viikinkaari 1, 00014 University of Helsinki, Finland (S.B.),
| | - Hugo Hofhuis
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Bjorn Pieper
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Maria Cartolano
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Ulla Neumann
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Lachezar A. Nikolov
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Baoxing Song
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Mohsen Hajheidari
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Roman Briskine
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Evangelia Kougioumoutzi
- Department of Plant Sciences, University of Oxford, South Parks Road, OX1 3RB Oxford UK
- Present Address: †Present address: Department of Biology and Biotechnology, Università La Sapienza, P.le Aldo Moro, 5, 00185 Rome, Italy (R.D.I.). The Global Food Security, BBSRC, Polaris House, North Star Avenue, Swindon SN2 1UH, UK (E.K.). Institute of Biotechnology, Viikinkaari 1, 00014 University of Helsinki, Finland (S.B.),
| | - Daniela Vlad
- Department of Plant Sciences, University of Oxford, South Parks Road, OX1 3RB Oxford UK
| | - Suvi Broholm
- Department of Plant Sciences, University of Oxford, South Parks Road, OX1 3RB Oxford UK
- Present Address: †Present address: Department of Biology and Biotechnology, Università La Sapienza, P.le Aldo Moro, 5, 00185 Rome, Italy (R.D.I.). The Global Food Security, BBSRC, Polaris House, North Star Avenue, Swindon SN2 1UH, UK (E.K.). Institute of Biotechnology, Viikinkaari 1, 00014 University of Helsinki, Finland (S.B.),
| | - Jotun Hein
- Department of Statistics, University of Oxford, 1 South Parks Road, OX1 3TG Oxford UK
| | - Khalid Meksem
- Department of Plant, Soil and Agricultural Systems, Southern Illinois University, Carbondale, 62901 Illinois USA
| | - David Lightfoot
- Department of Plant, Soil and Agricultural Systems, Southern Illinois University, Carbondale, 62901 Illinois USA
| | - Kentaro K. Shimizu
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Rie Shimizu-Inatsugi
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Martha Imprialou
- Department of Statistics, University of Oxford, 1 South Parks Road, OX1 3TG Oxford UK
| | - David Kudrna
- Arizona Genomics Institute, School of Plant Sciences and BIO5 Institute for Collaborative Research, University of Arizona, 1657 East Helen Street, Tucson, 85721 Arizona USA
| | - Rod Wing
- Arizona Genomics Institute, School of Plant Sciences and BIO5 Institute for Collaborative Research, University of Arizona, 1657 East Helen Street, Tucson, 85721 Arizona USA
| | - Shusei Sato
- Department of Plant Sciences, University of Oxford, South Parks Road, OX1 3RB Oxford UK
| | - Peter Huijser
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
| | - Dmitry Filatov
- Department of Plant Sciences, University of Oxford, South Parks Road, OX1 3RB Oxford UK
| | - Klaus F. X. Mayer
- Plant Genome and Systems Biology, Helmholtz Zentrum Munich, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Richard Mott
- UCL Genetics Institute, University College London, Gower Street, WC1E 6BT London UK
| | - Miltos Tsiantis
- Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Köln, Germany
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6
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Klein A, Schultner E, Lowak H, Schrader L, Heinze J, Holman L, Oettler J. Evolution of Social Insect Polyphenism Facilitated by the Sex Differentiation Cascade. PLoS Genet 2016; 12:e1005952. [PMID: 27031240 PMCID: PMC4816456 DOI: 10.1371/journal.pgen.1005952] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/02/2016] [Indexed: 11/18/2022] Open
Abstract
The major transition to eusociality required the evolution of a switch to canalize development into either a reproductive or a helper, the nature of which is currently unknown. Following predictions from the ‘theory of facilitated variation’, we identify sex differentiation pathways as promising candidates because of their pre-adaptation to regulating development of complex phenotypes. We show that conserved core genes, including the juvenile hormone-sensitive master sex differentiation gene doublesex (dsx) and a krüppel homolog 2 (kr-h2) with putative regulatory function, exhibit both sex and morph-specific expression across life stages in the ant Cardiocondyla obscurior. We hypothesize that genes in the sex differentiation cascade evolved perception of alternative input signals for caste differentiation (i.e. environmental or genetic cues), and that their inherent switch-like and epistatic behavior facilitated signal transfer to downstream targets, thus allowing them to control differential development into morphological castes. Division of labor into reproductive queens and helper workers in the societies of ants, bees and wasps is achieved by phenotypic plasticity, which allows individuals to embark on discrete developmental trajectories in response to variable signals. These signals can be genetic, epigenetic or environmental, thereby resembling the extreme variation in signals for sex determination across multicellular animals. We show that common developmental pathways downstream of these input signals, including the conserved sex differentiation gene doublesex, regulate sex and caste-specific phenotypic differentiation in the ant species Cardiocondyla obscurior. Many different mechanisms of gene regulation have been implicated in controlling caste-specific development in social insects but these all depend on a higher-level genetic switch. We propose that highly conserved hub genes such as dsx, which can translate variable input signals into large transcription differences using intermediate-level regulators, are tightly linked with the repeated evolutionary transition to eusociality and caste polyphenism.
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Affiliation(s)
- Antonia Klein
- Institut für Zoologie, Universität Regensburg, Regensburg, Germany
| | - Eva Schultner
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Helena Lowak
- Institut für Zoologie, Universität Regensburg, Regensburg, Germany
| | - Lukas Schrader
- Institut für Zoologie, Universität Regensburg, Regensburg, Germany
| | - Jürgen Heinze
- Institut für Zoologie, Universität Regensburg, Regensburg, Germany
| | - Luke Holman
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Jan Oettler
- Institut für Zoologie, Universität Regensburg, Regensburg, Germany
- * E-mail:
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7
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Zhong Z, Yang L, Zhang YE, Xue Y, He S. Correlated expression of retrocopies and parental genes in zebrafish. Mol Genet Genomics 2015; 291:723-37. [PMID: 26561303 DOI: 10.1007/s00438-015-1140-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 10/27/2015] [Indexed: 12/15/2022]
Abstract
Previous studies of the function and evolution of retrocopies in plants, Drosophila and non-mammalian chordates provided new insights into the origin of novel genes. However, little is known about retrocopies and their parental genes in teleosts, and it remains obscure whether there is any correlation between them. The present study aimed to characterize the spatial and temporal expression profiles of retrogenes and their parental genes based on RNA-Seq data from Danio rerio embryos and tissues from adult. Using a modified pipeline, 306 retrocopies were identified in the zebrafish genome, most of which exhibited ancient retroposition, and 76 of these showed a Ks < 2.0. Expression of a retrocopy is generally expected to present no correlation with its parental gene, as regulatory regions are not part of the retroposition event. Here, this assumption was tested based on RNA-Seq data from eight stages and thirteen tissue types of zebrafish. However, the result suggested that retrocopies displayed correlated expression with their parental genes. The level of correlation was found to decrease during embryogenesis, but to increase slightly within a tissue using Ks as the proxy for the divergence time. Tissue specificity was also observed: retrocopies were found to be expressed at a more specific level compared with their parental genes. Unlike Drosophila, which has sex chromosomes, zebrafish do not show testis-biased expression. Our study elaborated temporal and spatial patterns of expression of retrocopies in zebrafish, examined the correlation between retrocopies and parental genes and analyzed potential source of regulated elements of retrocopies, which lay a foundation for further functional study of retrocopies.
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Affiliation(s)
- Zaixuan Zhong
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, Hubei, People's Republic of China.,University of Chinese Academy of Sciences, Beijing, 100039, People's Republic of China
| | - Liandong Yang
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, Hubei, People's Republic of China.,University of Chinese Academy of Sciences, Beijing, 100039, People's Republic of China
| | - Yong E Zhang
- Key Laboratory of the Zoological Systematic and Evolution & State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Beijing, 100000, People's Republic of China.,University of Chinese Academy of Sciences, Beijing, 100039, People's Republic of China
| | - Yu Xue
- Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, People's Republic of China
| | - Shunping He
- The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, Hubei, People's Republic of China.
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8
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Miyakawa MO, Mikheyev AS. QTL Mapping of Sex Determination Loci Supports an Ancient Pathway in Ants and Honey Bees. PLoS Genet 2015; 11:e1005656. [PMID: 26544972 PMCID: PMC4636138 DOI: 10.1371/journal.pgen.1005656] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/17/2015] [Indexed: 12/27/2022] Open
Abstract
Sex determination mechanisms play a central role in life-history characteristics, affecting mating systems, sex ratios, inbreeding tolerance, etc. Downstream components of sex determination pathways are highly conserved, but upstream components evolve rapidly. Evolutionary dynamics of sex determination remain poorly understood, particularly because mechanisms appear so diverse. Here we investigate the origins and evolution of complementary sex determination (CSD) in ants and bees. The honey bee has a well-characterized CSD locus, containing tandemly arranged homologs of the transformer gene [complementary sex determiner (csd) and feminizer (fem)]. Such tandem paralogs appear frequently in aculeate hymenopteran genomes. However, only comparative genomic, but not functional, data support a broader role for csd/fem in sex determination, and whether species other than the honey bee use this pathway remains controversial. Here we used a backcross to test whether csd/fem acts as a CSD locus in an ant (Vollenhovia emeryi). After sequencing and assembling the genome, we computed a linkage map, and conducted a quantitative trait locus (QTL) analysis of diploid male production using 68 diploid males and 171 workers. We found two QTLs on separate linkage groups (CsdQTL1 and CsdQTL2) that jointly explained 98.0% of the phenotypic variance. CsdQTL1 included two tandem transformer homologs. These data support the prediction that the same CSD mechanism has indeed been conserved for over 100 million years. CsdQTL2 had no similarity to CsdQTL1 and included a 236-kb region with no obvious CSD gene candidates, making it impossible to conclusively characterize it using our data. The sequence of this locus was conserved in at least one other ant genome that diverged >75 million years ago. By applying QTL analysis to ants for the first time, we support the hypothesis that elements of hymenopteran CSD are ancient, but also show that more remains to be learned about the diversity of CSD mechanisms. Whether a developing embryo becomes male or female has significant downstream consequences. Depending on the species, sex can be determined by a wide variety of mechanisms. Sex determination systems can evolve rapidly, but how this occurs, and even how widespread the same mechanism is within a given taxonomic group, remains largely unknown. By experimentally mapping the sex determination architecture in the ant, Vollenhovia emeryi, we found that the well-characterized honey bee sex determination locus originated more than 100 million years ago. However, we also found an additional locus that has no homology to the first. Currently uncharacterized, this locus suggests that different species may use a variety of complementary sex determination mechanisms. Yet, core elements of the complementary sex determination machinery appear to be ancient.
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Affiliation(s)
- Misato O. Miyakawa
- Ecology and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, Tancha, Onna-son, Japan
| | - Alexander S. Mikheyev
- Ecology and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, Tancha, Onna-son, Japan
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
- * E-mail:
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9
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Biewer M, Lechner S, Hasselmann M. Similar but not the same: insights into the evolutionary history of paralogous sex-determining genes of the dwarf honey bee Apis florea. Heredity (Edinb) 2015; 116:12-22. [PMID: 26153222 DOI: 10.1038/hdy.2015.60] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 05/01/2015] [Accepted: 05/06/2015] [Indexed: 01/07/2023] Open
Abstract
Studying the fate of duplicated genes provides informative insight into the evolutionary plasticity of biological pathways to which they belong. In the paralogous sex-determining genes complementary sex determiner (csd) and feminizer (fem) of honey bee species (genus Apis), only heterozygous csd initiates female development. Here, the full-length coding sequences of the genes csd and fem of the phylogenetically basal dwarf honey bee Apis florea are characterized. Compared with other Apis species, remarkable evolutionary changes in the formation and localization of a protein-interacting (coiled-coil) motif and in the amino acids coding for the csd characteristic hypervariable region (HVR) are observed. Furthermore, functionally different csd alleles were isolated as genomic fragments from a random population sample. In the predicted potential specifying domain (PSD), a high ratio of πN/πS=1.6 indicated positive selection, whereas signs of balancing selection, commonly found in other Apis species, are missing. Low nucleotide diversity on synonymous and genome-wide, non-coding sites as well as site frequency analyses indicated a strong impact of genetic drift in A. florea, likely linked to its biology. Along the evolutionary trajectory of ~30 million years of csd evolution, episodic diversifying selection seems to have acted differently among distinct Apis branches. Consistently low amino-acid differences within the PSD among pairs of functional heterozygous csd alleles indicate that the HVR is the most important region for determining allele specificity. We propose that in the early history of the lineage-specific fem duplication giving rise to csd in Apis, A. florea csd stands as a remarkable example for the plasticity of initial sex-determining signals.
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Affiliation(s)
- M Biewer
- Department of Livestock Population Genomics, Institute of Animal Science, University of Hohenheim, Stuttgart, Germany
| | - S Lechner
- CeGaT GmbH - Center for Genomics and Transcriptomics, Tübingen, Germany
| | - M Hasselmann
- Department of Livestock Population Genomics, Institute of Animal Science, University of Hohenheim, Stuttgart, Germany
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10
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Biewer M, Schlesinger F, Hasselmann M. The evolutionary dynamics of major regulators for sexual development among Hymenoptera species. Front Genet 2015; 6:124. [PMID: 25914717 PMCID: PMC4392698 DOI: 10.3389/fgene.2015.00124] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 03/16/2015] [Indexed: 11/28/2022] Open
Abstract
All hymenopteran species, such as bees, wasps and ants, are characterized by the common principle of haplodiploid sex determination in which haploid males arise from unfertilized eggs and females from fertilized eggs. The underlying molecular mechanism has been studied in detail in the western honey bee Apis mellifera, in which the gene complementary sex determiner (csd) acts as primary signal of the sex determining pathway, initiating female development by csd-heterozygotes. Csd arose from gene duplication of the feminizer (fem) gene, a transformer (tra) ortholog, and mediates in conjunction with transformer2 (tra2) sex-specific splicing of fem. Comparative molecular analyses identified fem/tra and its downstream target doublesex (dsx) as conserved unit within the sex determining pathway of holometabolous insects. In this study, we aim to examine evolutionary differences among these key regulators. Our main hypothesis is that sex determining key regulators in Hymenoptera species show signs of coevolution within single phylogenetic lineages. We take advantage of several newly sequenced genomes of bee species to test this hypothesis using bioinformatic approaches. We found evidences that duplications of fem are restricted to certain bee lineages and notable amino acid differences of tra2 between Apis and non-Apis species propose structural changes in Tra2 protein affecting co-regulatory function on target genes. These findings may help to gain deeper insights into the ancestral mode of hymenopteran sex determination and support the common view of the remarkable evolutionary flexibility in this regulatory pathway.
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Affiliation(s)
- Matthias Biewer
- Population Genetics of Social Insects, Institute of Genetics, University of Cologne Cologne, Germany ; Livestock Population Genomics Group, Institute of Animal Science, University of Hohenheim Stuttgart, Germany
| | - Francisca Schlesinger
- Population Genetics of Social Insects, Institute of Genetics, University of Cologne Cologne, Germany ; Institute of Bee Research Hohen Neuendorf, Germany
| | - Martin Hasselmann
- Population Genetics of Social Insects, Institute of Genetics, University of Cologne Cologne, Germany ; Livestock Population Genomics Group, Institute of Animal Science, University of Hohenheim Stuttgart, Germany
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Independent evolutionary origin of fem paralogous genes and complementary sex determination in hymenopteran insects. PLoS One 2014; 9:e91883. [PMID: 24743790 PMCID: PMC3990544 DOI: 10.1371/journal.pone.0091883] [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] [Received: 04/03/2013] [Accepted: 02/17/2014] [Indexed: 12/23/2022] Open
Abstract
The primary signal of sex determination in the honeybee, the complementary sex determiner (csd) gene, evolved from a gene duplication event from an ancestral copy of the fem gene. Recently, other paralogs of the fem gene have been identified in several ant and bumblebee genomes. This discovery and the close phylogenetic relationship of the paralogous gene sequences led to the hypothesis of a single ancestry of the csd genetic system of complementary sex determination in the Hymenopteran insects, in which the fem and csd gene copies evolved as a unit in concert with the mutual transfers of sequences (concerted evolution). Here, we show that the paralogous gene copies evolved repeatedly through independent gene duplication events in the honeybee, bumblebee, and ant lineage. We detected no sequence tracts that would indicate a DNA transfer between the fem and the fem1/csd genes between different ant and bee species. Instead, we found tracts of duplication events in other genomic locations, suggesting that gene duplication was a frequent event in the evolution of these genes. These and other evidences suggest that the fem1/csd gene originated repeatedly through gene duplications in the bumblebee, honeybee, and ant lineages in the last 100 million years. Signatures of concerted evolution were not detectable, implicating that the gene tree based on neutral synonymous sites represents the phylogenetic relationships and origins of the fem and fem1/csd genes. Our results further imply that the fem1 and csd gene in bumblebees, honeybees, and ants are not orthologs, because they originated independently from the fem gene. Hence, the widely shared and conserved complementary sex determination mechanism in Hymenopteran insects is controlled by different genes and molecular processes. These findings highlight the limits of comparative genomics and emphasize the requirement to study gene functions in different species and major hymenopteran lineages.
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12
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Geuverink E, Beukeboom LW. Phylogenetic distribution and evolutionary dynamics of the sex determination genes doublesex and transformer in insects. Sex Dev 2013; 8:38-49. [PMID: 24401160 DOI: 10.1159/000357056] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Sex determination in insects is characterized by a gene cascade that is conserved at the bottom but contains diverse primary signals at the top. The bottom master switch gene doublesex is found in all insects. Its upstream regulator transformer is present in the orders Hymenoptera, Coleoptera and Diptera, but has thus far not been found in Lepidoptera and in the basal lineages of Diptera. transformer is presumed to be ancestral to the holometabolous insects based on its shared domains and conserved features of autoregulation and sex-specific splicing. We interpret that its absence in basal lineages of Diptera and its order-specific conserved domains indicate multiple independent losses or recruitments into the sex determination cascade. Duplications of transformer are found in derived families within the Hymenoptera, characterized by their complementary sex determination mechanism. As duplications are not found in any other insect order, they appear linked to the haplodiploid reproduction of the Hymenoptera. Further phylogenetic analyses combined with functional studies are needed to understand the evolutionary history of the transformer gene among insects.
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Affiliation(s)
- E Geuverink
- Evolutionary Genetics, Center for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands
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13
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Bopp D, Saccone G, Beye M. Sex determination in insects: variations on a common theme. Sex Dev 2013; 8:20-8. [PMID: 24335049 DOI: 10.1159/000356458] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Recent studies in a representative selection of holometabolous insects suggest that, despite diversity at the instructive level, the signal-relaying part of the sex-determining pathway is remarkably well conserved. In principle, it is composed of the transformer gene (tra), which acts as a common binary switch that transduces the selected sexual fate, female when ON, male when OFF, to the downstream effector doublesex(dsx) that controls overt sexual differentiation. An interesting recurrent feature is that tra is switched ON in the early zygote by maternally provisioned tra activity. Different male-determining signals evolved, which prevent maternal activation of zygotic tra to allow for male development. In some species, where lack of maternal activation leaves tra in the OFF state, novel female-determining signals were deployed to activate zygotic tra. It appears that both the instructive end of the pathway upstream of tra as well as the executive end downstream of dsx are primary targets of evolutionary divergence, while the transduction part seems less prone to changes. We propose that this is a feature shared with many other signaling cascades that regulate developmental fates.
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Affiliation(s)
- D Bopp
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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14
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Beye M, Seelmann C, Gempe T, Hasselmann M, Vekemans X, Fondrk MK, Page RE. Gradual molecular evolution of a sex determination switch through incomplete penetrance of femaleness. Curr Biol 2013; 23:2559-64. [PMID: 24316208 DOI: 10.1016/j.cub.2013.10.070] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 09/30/2013] [Accepted: 10/29/2013] [Indexed: 01/08/2023]
Abstract
Some genes regulate phenotypes that are either present or absent. They are often important regulators of developmental switches and are involved in morphological evolution. We have little understanding of the molecular mechanisms by which these absence/presence gene functions have evolved, because the phenotype and fitness of molecular intermediate forms are unknown. Here, we studied the sex-determining switch of 14 natural sequence variants of the csd gene among 76 genotypes of the honeybee (Apis mellifera). Heterozygous genotypes (different specificities) of the csd gene determine femaleness, while hemizygous genotypes (single specificity) determine maleness. Homozygous genotypes of the csd gene (same specificity) are lethal. We found that at least five amino acid differences and length variation between Csd specificities in the specifying domain (PSD) were sufficient to regularly induce femaleness. We estimated that, on average, six pairwise amino acid differences evolved under positive selection. We also identified a natural evolutionary intermediate that showed only three amino acid length differences in the PSD relative to its parental allele. This genotype showed an intermediate fitness because it implemented lethality regularly and induced femaleness infrequently (i.e., incomplete penetrance). We suggest incomplete penetrance as a mechanism through which new molecular switches can gradually and adaptively evolve.
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Affiliation(s)
- Martin Beye
- Institute of Evolutionary Genetics, Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, 40225 Duesseldorf, Germany.
| | - Christine Seelmann
- Institute of Evolutionary Genetics, Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, 40225 Duesseldorf, Germany
| | - Tanja Gempe
- Institute of Evolutionary Genetics, Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, 40225 Duesseldorf, Germany
| | - Martin Hasselmann
- Institute of Genetics, University of Cologne, Zuelpicher Straße 47, 50674 Koeln, Germany
| | - Xavier Vekemans
- Laboratoire de Génétique et Evolution des Populations Végétales, UMR 8198, CNRS, Université Lille 1, 59655 Villeneuve d'Ascq, France
| | - M Kim Fondrk
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Robert E Page
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA
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15
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Lechner S, Ferretti L, Schöning C, Kinuthia W, Willemsen D, Hasselmann M. Nucleotide variability at its limit? Insights into the number and evolutionary dynamics of the sex-determining specificities of the honey bee Apis mellifera. Mol Biol Evol 2013; 31:272-87. [PMID: 24170493 PMCID: PMC3907057 DOI: 10.1093/molbev/mst207] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Deciphering the evolutionary processes driving nucleotide variation in multiallelic genes is limited by the number of genetic systems in which such genes occur. The complementary sex determiner (csd) gene in the honey bee Apis mellifera is an informative example for studying allelic diversity and the underlying evolutionary forces in a well-described model of balancing selection. Acting as the primary signal of sex determination, diploid individuals heterozygous for csd develop into females, whereas csd homozygotes are diploid males that have zero fitness. Examining 77 of the functional heterozygous csd allele pairs, we established a combinatorical criteria that provide insights into the minimum number of amino acid differences among those pairs. Given a data set of 244 csd sequences, we show that the total number of csd alleles found in A. mellifera ranges from 53 (locally) to 87 (worldwide), which is much higher than was previously reported (20). Using a coupon-collector model, we extrapolate the presence of in total 116–145 csd alleles worldwide. The hypervariable region (HVR) is of particular importance in determining csd allele specificity, and we provide for this region evidence of high evolutionary rate for length differences exceeding those of microsatellites. The proportion of amino acids driven by positive selection and the rate of nonsynonymous substitutions in the HVR-flanking regions reach values close to 1 but differ with respect to the HVR length. Using a model of csd coalescence, we identified the high originating rate of csd specificities as a major evolutionary force, leading to an origin of a novel csd allele every 400,000 years. The csd polymorphism frequencies in natural populations indicate an excess of new mutations, whereas signs of ancestral transspecies polymorphism can still be detected. This study provides a comprehensive view of the enormous diversity and the evolutionary forces shaping a multiallelic gene.
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Affiliation(s)
- Sarah Lechner
- Institute of Evolutionary Genetics, Heinrich-Heine University Duesseldorf, Duesseldorf, Germany
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16
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Abstract
Eusocial Hymenoptera, such as the European honey bee, Apis mellifera, have the highest recombination rates of multicellular animals.(1) Recently, we showed(2) that a side-effect of recombination in the honey bee, GC biased gene conversion (bGC), helps maintain the unusual bimodal GC-content distribution of the bee genome by increasing GC-content in high recombination areas while low recombination areas are losing GC-content because of biased AT mutations and low rates of bGC. Although the very high recombination rate of A. mellifera makes GC-content evolution easier to study, the pattern is consistent with results found in many other species including mammals and yeast.(3) Also consistent across phyla is the association of higher genetic diversity and divergence with high GC and high recombination areas.(4) (,) (5) Finally, we showed that genes overexpressed in the brains of workers cluster in GC-rich genomic areas with the highest rates of recombination and molecular evolution.(2) In this Addendum we present a conceptual model of how eusociality and high recombination rates may co-evolve.
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Affiliation(s)
- Clement F Kent
- Department of Biology; York University; Toronto, ON Canada
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17
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Privman E, Wurm Y, Keller L. Duplication and concerted evolution in a master sex determiner under balancing selection. Proc Biol Sci 2013; 280:20122968. [PMID: 23466984 DOI: 10.1098/rspb.2012.2968] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The transformer (tra) gene is a key regulator in the signalling hierarchy controlling all aspects of somatic sexual differentiation in Drosophila and other insects. Here, we show that six of the seven sequenced ants have two copies of tra. Surprisingly, the two paralogues are always more similar within species than among species. Comparative sequence analyses indicate that this pattern is owing to the ongoing concerted evolution after an ancestral duplication rather than independent duplications in each of the six species. In particular, there was strong support for inter-locus recombination between the paralogues of the ant Atta cephalotes. In the five species where the location of paralogues is known, they are adjacent to each other in four cases and separated by only few genes in the fifth case. Because there have been extensive genomic rearrangements in these lineages, this suggests selection acting to conserve their synteny. In three species, we also find a signature of positive selection in one of the paralogues. In three bee species where information is available, the tra gene is also duplicated, the copies are adjacent and in at least one species there was recombination between paralogues. These results suggest that concerted evolution plays an adaptive role in the evolution of this gene family.
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Affiliation(s)
- Eyal Privman
- Department of Ecology and Evolution, University of Lausanne, Lausanne 1015, Switzerland
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18
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Serbielle C, Dupas S, Perdereau E, Héricourt F, Dupuy C, Huguet E, Drezen JM. Evolutionary mechanisms driving the evolution of a large polydnavirus gene family coding for protein tyrosine phosphatases. BMC Evol Biol 2012; 12:253. [PMID: 23270369 PMCID: PMC3573978 DOI: 10.1186/1471-2148-12-253] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 12/11/2012] [Indexed: 11/20/2022] Open
Abstract
Background Gene duplications have been proposed to be the main mechanism involved in genome evolution and in acquisition of new functions. Polydnaviruses (PDVs), symbiotic viruses associated with parasitoid wasps, are ideal model systems to study mechanisms of gene duplications given that PDV genomes consist of virulence genes organized into multigene families. In these systems the viral genome is integrated in a wasp chromosome as a provirus and virus particles containing circular double-stranded DNA are injected into the parasitoids’ hosts and are essential for parasitism success. The viral virulence factors, organized in gene families, are required collectively to induce host immune suppression and developmental arrest. The gene family which encodes protein tyrosine phosphatases (PTPs) has undergone spectacular expansion in several PDV genomes with up to 42 genes. Results Here, we present strong indications that PTP gene family expansion occurred via classical mechanisms: by duplication of large segments of the chromosomally integrated form of the virus sequences (segmental duplication), by tandem duplications within this form and by dispersed duplications. We also propose a novel duplication mechanism specific to PDVs that involves viral circle reintegration into the wasp genome. The PTP copies produced were shown to undergo conservative evolution along with episodes of adaptive evolution. In particular recently produced copies have undergone positive selection in sites most likely involved in defining substrate selectivity. Conclusion The results provide evidence about the dynamic nature of polydnavirus proviral genomes. Classical and PDV-specific duplication mechanisms have been involved in the production of new gene copies. Selection pressures associated with antagonistic interactions with parasitized hosts have shaped these genes used to manipulate lepidopteran physiology with evidence for positive selection involved in adaptation to host targets.
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Affiliation(s)
- Céline Serbielle
- Institut de Recherche sur la Biologie de l'Insecte, UMR CNRS 7261, Faculté des Sciences et Techniques, Université F. Rabelais, Parc de Grandmont, 37200, Tours, France
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Weadick CJ, Chang BSW. Complex patterns of divergence among green-sensitive (RH2a) African cichlid opsins revealed by Clade model analyses. BMC Evol Biol 2012; 12:206. [PMID: 23078361 PMCID: PMC3514295 DOI: 10.1186/1471-2148-12-206] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 10/09/2012] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Gene duplications play an important role in the evolution of functional protein diversity. Some models of duplicate gene evolution predict complex forms of paralog divergence; orthologous proteins may diverge as well, further complicating patterns of divergence among and within gene families. Consequently, studying the link between protein sequence evolution and duplication requires the use of flexible substitution models that can accommodate multiple shifts in selection across a phylogeny. Here, we employed a variety of codon substitution models, primarily Clade models, to explore how selective constraint evolved following the duplication of a green-sensitive (RH2a) visual pigment protein (opsin) in African cichlids. Past studies have linked opsin divergence to ecological and sexual divergence within the African cichlid adaptive radiation. Furthermore, biochemical and regulatory differences between the RH2aα and RH2aβ paralogs have been documented. It thus seems likely that selection varies in complex ways throughout this gene family. RESULTS Clade model analysis of African cichlid RH2a opsins revealed a large increase in the nonsynonymous-to-synonymous substitution rate ratio (ω) following the duplication, as well as an even larger increase, one consistent with positive selection, for Lake Tanganyikan cichlid RH2aβ opsins. Analysis using the popular Branch-site models, by contrast, revealed no such alteration of constraint. Several amino acid sites known to influence spectral and non-spectral aspects of opsin biochemistry were found to be evolving divergently, suggesting that orthologous RH2a opsins may vary in terms of spectral sensitivity and response kinetics. Divergence appears to be occurring despite intronic gene conversion among the tandemly-arranged duplicates. CONCLUSIONS Our findings indicate that variation in selective constraint is associated with both gene duplication and divergence among orthologs in African cichlid RH2a opsins. At least some of this variation may reflect an adaptive response to differences in light environment. Interestingly, these patterns only became apparent through the use of Clade models, not through the use of the more widely employed Branch-site models; we suggest that this difference stems from the increased flexibility associated with Clade models. Our results thus bear both on studies of cichlid visual system evolution and on studies of gene family evolution in general.
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Affiliation(s)
- Cameron J Weadick
- Department of Evolutionary Biology, Max Planck Institutefor Developmental Biology, Spemmanstr. 37, Tuebingen 72076, Germany
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20
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Song J, Shi L, Li D, Sun Y, Niu Y, Chen Z, Luo H, Pang X, Sun Z, Liu C, Lv A, Deng Y, Larson-Rabin Z, Wilkinson M, Chen S. Extensive pyrosequencing reveals frequent intra-genomic variations of internal transcribed spacer regions of nuclear ribosomal DNA. PLoS One 2012; 7:e43971. [PMID: 22952830 PMCID: PMC3431384 DOI: 10.1371/journal.pone.0043971] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Accepted: 07/27/2012] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Internal transcribed spacer of nuclear ribosomal DNA (nrDNA) is already one of the most popular phylogenetic and DNA barcoding markers. However, the existence of its multiple copies has complicated such usage and a detailed characterization of intra-genomic variations is critical to address such concerns. METHODOLOGY/PRINCIPAL FINDINGS In this study, we used sequence-tagged pyrosequencing and genome-wide analyses to characterize intra-genomic variations of internal transcribed spacer 2 (ITS2) regions from 178 plant species. We discovered that mutation of ITS2 is frequent, with a mean of 35 variants per species. And on average, three of the most abundant variants make up 91% of all ITS2 copies. Moreover, we found different congeneric species share identical variants in 13 genera. Interestingly, different species across different genera also share identical variants. In particular, one minor variant of ITS2 in Eleutherococcus giraldii was found identical to the ITS2 major variant of Panax ginseng, both from Araliaceae family. In addition, DNA barcoding gap analysis showed that the intra-genomic distances were markedly smaller than those of the intra-specific or inter-specific variants. When each of 5543 variants were examined for its species discrimination efficiency, a 97% success rate was obtained at the species level. CONCLUSIONS Identification of identical ITS2 variants across intra-generic or inter-generic species revealed complex species evolutionary history, possibly, horizontal gene transfer and ancestral hybridization. Although intra-genomic multiple variants are frequently found within each genome, the usage of the major variants alone is sufficient for phylogeny construction and species determination in most cases. Furthermore, the inclusion of minor variants further improves the resolution of species identification.
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Affiliation(s)
- Jingyuan Song
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Linchun Shi
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Dezhu Li
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Yongzhen Sun
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Yunyun Niu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Zhiduan Chen
- Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Hongmei Luo
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Xiaohui Pang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Zhiying Sun
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Chang Liu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - Aiping Lv
- China Academy of Chinese Medical Sciences, Beijing, China
| | - Youping Deng
- Rush University Medical Center, Chicago, Illinois, United States of America
| | - Zachary Larson-Rabin
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | | | - Shilin Chen
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
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21
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Ellis JS, Turner LM, Knight ME. Patterns of selection and polymorphism of innate immunity genes in bumblebees (Hymenoptera: Apidae). Genetica 2012; 140:205-17. [PMID: 22899493 DOI: 10.1007/s10709-012-9672-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 08/07/2012] [Indexed: 01/22/2023]
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22
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Mullon C, Pomiankowski A, Reuter M. Molecular evolution of Drosophila Sex-lethal and related sex determining genes. BMC Evol Biol 2012; 12:5. [PMID: 22244243 PMCID: PMC3292462 DOI: 10.1186/1471-2148-12-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 01/14/2012] [Indexed: 12/23/2022] Open
Abstract
Background Sex determining mechanisms are evolutionarily labile and related species often use different primary signals and gene regulatory networks. This is well illustrated by the sex determining cascade of Drosophila fruitflies, which have recruited Sex-lethal as the master switch and cellular memory of sexual identity, a role performed in other insects by the gene transformer. Here we investigate the evolutionary change in the coding sequences of sex determining genes associated with the recruitment of Sex-lethal. We analyze sequences of Sex-lethal itself, its Drosophila paralogue sister-or-Sex-lethal and downstream targets transformer and doublesex. Results We find that the recruitment of sister-or-Sex-lethal was associated with a number of adaptive amino acid substitutions, followed by a tightening of purifying selection within the Drosophila clade. Sequences of the paralogue sister-or-Sex-lethal, in contrast, show a signature of rampant positive selection and relaxation of purifying selection. The recruitment of Sex-lethal as top regulator and memory gene is associated with a significant release from purifying selection in transformer throughout the Drosophila clade. In addition, doublesex shows a signature of positive selection and relaxation of purifying selection in the Drosophila clade. A similar pattern is seen in sequences from the sister Tephritidae clade. Conclusions The pattern of molecular evolution we observe for Sex-lethal and its paralogue sister-or-Sex-lethal is not characteristic of a duplication followed by neo-functionalization. Rather, evidence suggests a sub-functionalization scenario achieved through the evolution of sophisticated splicing. As expected, we find that transformer evolves under relaxed purifying selection after the recruitment of Sex-lethal in Drosophila. Finally, the observation of doublesex adaptation in both Drosophila and Tephritidae suggests that these changes are due to ongoing adaptation of downstream sex-specific regulation, rather than being associated the recruitment of Sex-lethal and the resulting change in the topology of the sex determining cascade.
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Affiliation(s)
- Charles Mullon
- Department of Genetics, Environment and Evolution, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
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Abstract
Animals have evolved a bewildering diversity of mechanisms to determine the two sexes. Studies of sex determination genes – their history and function – in non-model insects and Drosophila have allowed us to begin to understand the generation of sex determination diversity. One common theme from these studies is that evolved mechanisms produce activities in either males or females to control a shared gene switch that regulates sexual development. Only a few small-scale changes in existing and duplicated genes are sufficient to generate large differences in sex determination systems. This review summarises recent findings in insects, surveys evidence of how and why sex determination mechanisms can change rapidly and suggests fruitful areas of future research.
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Affiliation(s)
- Tanja Gempe
- Department of Genetics, Heinrich Heine University, Duesseldorf, Universitaetsstrasse 1, Duesseldorf, Germany
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Gene duplicate holds back its sister. Nat Rev Genet 2010; 11:593. [DOI: 10.1038/nrg2850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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