1
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Münch L, Helmprobst F, Volff JN, Chalopin D, Schartl M, Kneitz S. Transposable Element Expression Profiles in Premalignant Pigment Cell Lesions and Melanoma of Xiphophorus. Genes (Basel) 2024; 15:620. [PMID: 38790249 PMCID: PMC11121471 DOI: 10.3390/genes15050620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/03/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
Transposable elements (TEs) are characterized by their ability to change their genomic position. Through insertion or recombination leading to deletions and other chromosomal aberrations, they can cause genetic instability. The extent to which they thereby exert regulatory influence on cellular functions is unclear. To better characterize TEs in processes such as carcinogenesis, we used the well-established Xiphophorus melanoma model. By transcriptome sequencing, we show that an increasing total number in transposons correlates with progression of malignancy in melanoma samples from Xiphophorus interspecific hybrids. Further, by comparing the presence of TEs in the parental genomes of Xiphophorus maculatus and Xiphophorus hellerii, we could show that even in closely related species, genomic location and spectrum of TEs are considerably different.
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Affiliation(s)
- Luca Münch
- Neurology Asklepios Klinik Barmbek, Rübenkamp 220, 22307 Hamburg, Germany;
| | - Frederik Helmprobst
- Institute of Neuropathology, Philipps-University Marburg, 35037 Marburg, Germany;
| | | | | | - Manfred Schartl
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 786666, USA
- Developmental Biochemistry, University of Würzburg, 97974 Würzburg, Germany
| | - Susanne Kneitz
- Biochemistry and Cell Biology, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany;
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2
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Schartl M, Lu Y. Validity of Xiphophorus fish as models for human disease. Dis Model Mech 2024; 17:dmm050382. [PMID: 38299666 PMCID: PMC10855230 DOI: 10.1242/dmm.050382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2024] Open
Abstract
Platyfish and swordtails of the genus Xiphophorus provide a well-established model for melanoma research and have become well known for this feature. Recently, modelling approaches for other human diseases in Xiphophorus have been developed or are emerging. This Review provides a comprehensive summary of these models and discusses how findings from basic biological and molecular studies and their translation to medical research demonstrate that Xiphophorus models have face, construct and predictive validity for studying a broad array of human diseases. These models can thus improve our understanding of disease mechanisms to benefit patients.
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Affiliation(s)
- Manfred Schartl
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
- Developmental Biochemistry, Theodor-Boveri Institute, Biocenter, University of Würzburg, Würzburg 97074, Germany
| | - Yuan Lu
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
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3
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Kawasaki T, Shimizu Y. Carcinogenesis Models Using Small Fish. Chem Pharm Bull (Tokyo) 2021; 69:962-969. [PMID: 34602577 DOI: 10.1248/cpb.c21-00295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Experimental animals are indispensable in life science-related research, including cancer studies. After rats and mice, small fishes, such as zebrafish and medaka, are the second most frequently used model species. Fish models have some advantageous physical characteristics that make them suitable for research, including their small size, some transparency, genetic manipulability, ease of handling, and highly ortholog correspondence with humans. This review introduces technological advances in carcinogenesis model production using small fish. Carcinogenesis model production begins with chemical carcinogenesis, followed by mutagenesis. Gene transfer technology has made it possible to incorporate various mechanisms that act on cancer-related genes in individuals. For example, scientists may now spatiotemporally control gene expression in a single fish through methods including the localization of an expression site via a tissue-specific promoter and expression control using light, heat, or a chemical substance. In addition, genome editing technology is realizing more specific and more efficient gene disruption than conventional mutagenesis, in which the disruption of the gene of interest depends on chance. These technological advances have improved animal models and will soon create carcinogenesis models that better mimic human pathology. We conclude by discussing future expectations for cancer research using small fish.
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Affiliation(s)
- Takashi Kawasaki
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)
| | - Yuki Shimizu
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)
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4
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Bailey NP, Stevison LS. Mitonuclear conflict in a macaque species exhibiting phylogenomic discordance. J Evol Biol 2021; 34:1568-1579. [PMID: 34379829 DOI: 10.1111/jeb.13914] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/28/2021] [Indexed: 12/19/2022]
Abstract
Speciation and hybridization are intertwined processes in the study of evolution. Hybridization between sufficiently diverged populations can result in genomic conflict within offspring, causing reduced viability and fertility, thus increasing divergence between populations. Conflicts between mitochondrial and nuclear genes are increasingly found to play a role in this process in various systems. We examine the possibility of this conflict in the bear macaque, Macaca arctoides (Primates: Cercopithecidae), a primate species exhibiting mitonuclear discordance due to extensive hybridization with species in the sinica and fascicularis groups. Here, divergence, introgression and natural selection of mitonuclear genes (N = 160) relative to nuclear control genes (N = 144) were analysed to determine whether there are evolutionary processes involved in resolving the potential conflict caused by mitonuclear discordance. Nucleotide divergence of mitonuclear genes is increased relative to control nuclear genes between M. arctoides and the species sharing its nuclear ancestry (p = 0.007), consistent with genetic conflict. However, measures of introgression and selection do not identify large-scale co-introgression or co-evolution as means to resolve mitonuclear conflict. Nonetheless, mitochondrial tRNA synthetases stand out in analyses using dN/dS and extended branch lengths as potential targets of selection. The methodology implemented provides a framework that can be used to examine the effects of mitonuclear co-introgression and co-evolution on a genomic scale in a variety of systems.
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Affiliation(s)
- Nick P Bailey
- Department of Biological Sciences, Auburn University, Auburn, AL, USA
| | - Laurie S Stevison
- Department of Biological Sciences, Auburn University, Auburn, AL, USA
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5
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Ishishita S, Tatsumoto S, Kinoshita K, Nunome M, Suzuki T, Go Y, Matsuda Y. Transcriptome analysis revealed misregulated gene expression in blastoderms of interspecific chicken and Japanese quail F1 hybrids. PLoS One 2020; 15:e0240183. [PMID: 33044996 PMCID: PMC7549780 DOI: 10.1371/journal.pone.0240183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 09/22/2020] [Indexed: 11/29/2022] Open
Abstract
Hybrid incompatibility, such as sterility and inviability, prevents gene flow between closely-related populations as a reproductive isolation barrier. F1 hybrids between chickens and Japanese quail (hereafter, referred to as quail), exhibit a high frequency of developmental arrest at the preprimitive streak stage. To investigate the molecular basis of the developmental arrest at the preprimitive streak stage in chicken–quail F1 hybrid embryos, we investigated chromosomal abnormalities in the hybrid embryos using molecular cytogenetic analysis. In addition, we quantified gene expression in parental species and chicken- and quail-derived allele-specific expression in the hybrids at the early blastoderm and preprimitive streak stages by mRNA sequencing. Subsequently, we compared the directions of change in gene expression, including upregulation, downregulation, or no change, from the early blastoderm stage to the preprimitive streak stage between parental species and their hybrids. Chromosome analysis revealed that the cells of the hybrid embryos contained a fifty-fifty mixture of parental chromosomes, and numerical chromosomal abnormalities were hardly observed in the hybrid cells. Gene expression analysis revealed that a part of the genes that were upregulated from the early blastoderm stage to the preprimitive streak stage in both parental species exhibited no upregulation of both chicken- and quail-derived alleles in the hybrids. GO term enrichment analysis revealed that these misregulated genes are involved in various biological processes, including ribosome-mediated protein synthesis and cell proliferation. Furthermore, the misregulated genes included genes involved in early embryonic development, such as primitive streak formation and gastrulation. These results suggest that numerical chromosomal abnormalities due to a segregation failure does not cause the lethality of chicken–quail hybrid embryos, and that the downregulated expression of the genes that are involved in various biological processes, including translation and primitive streak formation, mainly causes the developmental arrest at the preprimitive streak stage in the hybrids.
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Affiliation(s)
- Satoshi Ishishita
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Shoji Tatsumoto
- Cognitive Genomics Research Group, Exploratory Research Center on Life and Living Systems (ExCELLs), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Keiji Kinoshita
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Mitsuo Nunome
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Takayuki Suzuki
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
- Laboratory of Avian Bioscience, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Yasuhiro Go
- Cognitive Genomics Research Group, Exploratory Research Center on Life and Living Systems (ExCELLs), National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Yoichi Matsuda
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
- Laboratory of Avian Bioscience, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
- * E-mail:
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6
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The Colorful Sex Chromosomes of Teleost Fish. Genes (Basel) 2018; 9:genes9050233. [PMID: 29751562 PMCID: PMC5977173 DOI: 10.3390/genes9050233] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 04/24/2018] [Accepted: 04/24/2018] [Indexed: 12/14/2022] Open
Abstract
Teleost fish provide some of the most intriguing examples of sexually dimorphic coloration, which is often advantageous for only one of the sexes. Mapping studies demonstrated that the genetic loci underlying such color patterns are frequently in tight linkage to the sex-determining locus of a species, ensuring sex-specific expression of the corresponding trait. Several genes affecting color synthesis and pigment cell development have been previously described, but the color loci on the sex chromosomes have mostly remained elusive as yet. Here, we summarize the current knowledge about the genetics of such color loci in teleosts, mainly from studies on poeciliids and cichlids. Further studies on these color loci will certainly provide important insights into the evolution of sex chromosomes.
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7
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Warren IA, Naville M, Chalopin D, Levin P, Berger CS, Galiana D, Volff JN. Evolutionary impact of transposable elements on genomic diversity and lineage-specific innovation in vertebrates. Chromosome Res 2016; 23:505-31. [PMID: 26395902 DOI: 10.1007/s10577-015-9493-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Since their discovery, a growing body of evidence has emerged demonstrating that transposable elements are important drivers of species diversity. These mobile elements exhibit a great variety in structure, size and mechanisms of transposition, making them important putative actors in organism evolution. The vertebrates represent a highly diverse and successful lineage that has adapted to a wide range of different environments. These animals also possess a rich repertoire of transposable elements, with highly diverse content between lineages and even between species. Here, we review how transposable elements are driving genomic diversity and lineage-specific innovation within vertebrates. We discuss the large differences in TE content between different vertebrate groups and then go on to look at how they affect organisms at a variety of levels: from the structure of chromosomes to their involvement in the regulation of gene expression, as well as in the formation and evolution of non-coding RNAs and protein-coding genes. In the process of doing this, we highlight how transposable elements have been involved in the evolution of some of the key innovations observed within the vertebrate lineage, driving the group's diversity and success.
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Affiliation(s)
- Ian A Warren
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Magali Naville
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Domitille Chalopin
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France.,Department of Genetics, University of Georgia, Athens, Georgia, 30602, USA
| | - Perrine Levin
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Chloé Suzanne Berger
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Delphine Galiana
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, CNRS UMR5242, Ecole Normale Supérieure de Lyon, Lyon, France.
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8
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Brosius J. The persistent contributions of RNA to eukaryotic gen(om)e architecture and cellular function. Cold Spring Harb Perspect Biol 2014; 6:a016089. [PMID: 25081515 DOI: 10.1101/cshperspect.a016089] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Currently, the best scenario for earliest forms of life is based on RNA molecules as they have the proven ability to catalyze enzymatic reactions and harbor genetic information. Evolutionary principles valid today become apparent in such models already. Furthermore, many features of eukaryotic genome architecture might have their origins in an RNA or RNA/protein (RNP) world, including the onset of a further transition, when DNA replaced RNA as the genetic bookkeeper of the cell. Chromosome maintenance, splicing, and regulatory function via RNA may be deeply rooted in the RNA/RNP worlds. Mostly in eukaryotes, conversion from RNA to DNA is still ongoing, which greatly impacts the plasticity of extant genomes. Raw material for novel genes encoding protein or RNA, or parts of genes including regulatory elements that selection can act on, continues to enter the evolutionary lottery.
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Affiliation(s)
- Jürgen Brosius
- Institute of Experimental Pathology (ZMBE), University of Münster, D-48149 Münster, Germany
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9
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Dickman CTD, Moehring AJ. Contribution of the X chromosome to a marked reduction in lifespan in interspecies female hybrids of Drosophila simulans and D. mauritiana. J Evol Biol 2013; 27:25-33. [PMID: 24118420 DOI: 10.1111/jeb.12262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 09/06/2013] [Indexed: 11/30/2022]
Abstract
When two species come into contact and interbreed, the production of unfit hybrids can limit or prevent gene flow between the populations, thus maintaining each species' separate identity. The genetic basis of this hybrid dysfunction has recently begun to be elucidated, particularly for hybrid sterility and inviability. Although these dysfunctions can certainly act as a barrier to gene flow, other post-zygotic barriers may also play an important role in isolating species from one another. This study examines the genetic basis of the more subtle mechanism of species isolation via a marked reduction in lifespan of interspecies hybrid offspring. We found that females with homozygous X chromosomes in an otherwise interspecies hybrid background displayed a significant reduction in lifespan; this effect is not due to genetic background and appears to arise from complex genetic interactions. Separately, there is an additional severe reduction in lifespan for attached-X females when they have mated with males of either parental species, which is partly due to interspecific genetic interactions, but primarily due to a female's increased sensitivity to mating when bearing a Y chromosome or the attached-X chromosome construct.
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Affiliation(s)
- C T D Dickman
- Department of Biology, Western University, London, ON, Canada
| | - A J Moehring
- Department of Biology, Western University, London, ON, Canada
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10
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Zhou Q. A swimy locus on Y chromosome of the platyfish (Xiphophorus maculatus) is derived from a novel DNA transposon Zisupton. Gene 2012; 503:254-9. [PMID: 22579468 DOI: 10.1016/j.gene.2012.04.062] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Revised: 03/09/2012] [Accepted: 04/18/2012] [Indexed: 12/13/2022]
Abstract
A swimy locus derived from a novel DNA transposon Zisupton was located on the sex determination region (SD) of Xiphophorus maculatus. The analysis of expression pattern showed that swimy was exclusively expressed in adult testis in X. maculatus. The putative 939 aa sequence contains four Zn-finger domains, such as two C2H2 type, one NFX type and one SWIM type Zn-finger domain, and one SAP DNA-binding domain. Swimy has about 7 copies per haploid X. maculatus genome with Y-specific copies located in the SD region, and become the second new W-linked marker of platyfish. Analysis of the structure and distribution of this sex-linked marker is benefit to shed new light on the evolutionary dynamics of sex chromosomes in fish.
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Affiliation(s)
- Qingchun Zhou
- Physiologische Chemie I, Biozentrum, University of Würzburg, Würzburg 97074, Germany.
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11
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Fernandez AA, Paniker L, Garcia R, Mitchell DL. Recent advances in sunlight-induced carcinogenesis using the Xiphophorus melanoma model. Comp Biochem Physiol C Toxicol Pharmacol 2012; 155:64-70. [PMID: 21457786 PMCID: PMC3164944 DOI: 10.1016/j.cbpc.2011.03.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 03/23/2011] [Accepted: 03/23/2011] [Indexed: 01/25/2023]
Abstract
Unlike breast and prostate cancers, the nature and sequence of critical genetic and epigenetic events involved in the initiation and progression of melanoma are not well understood. A contributing factor to this dilemma, especially given our current understanding of the importance of UV light in melanoma etiology, is the lack of quality UV-inducible melanoma animal models. In this study we elaborate on the capability of UV light to induce cutaneous malignant melanomas (CMM) in Xiphophorus fishes, which were previously found to develop melanomas after acute neonatal UVB irradiation. In two separate tumorigenesis experiments, we exposed adult Xiphophorus hybrids to either acute UVB irradiations (5 consecutive daily treatments) or chronic solar irradiations (continuous UVA/UVB treatment for 9 months). Acute adult UVB irradiation resulted in the significant induction of melanomas, and moreover, this induction rate is equivalent to that of animals exposed to acute neonatal UVB irradiation. This study represents the first evidence that acute adult UVB irradiation, in the absence of any early life exposures, induces CMM. Similar to the findings conducted on other divergent melanoma models, including HGF/SF transgenic mice and Monodelphis domestica, prolonged chronic solar UV was not a factor in melanomagenesis.
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Affiliation(s)
- André A Fernandez
- The University of Texas MD Anderson Cancer Center, Department of Carcinogenesis, 1808 Park Road 1C, Smithville, TX 78957, USA.
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12
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Regneri J, Schartl M. Expression regulation triggers oncogenicity of xmrk alleles in the Xiphophorus melanoma system. Comp Biochem Physiol C Toxicol Pharmacol 2012; 155:71-80. [PMID: 21527356 DOI: 10.1016/j.cbpc.2011.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 04/08/2011] [Accepted: 04/12/2011] [Indexed: 11/28/2022]
Abstract
The Xiphophorus melanoma model has gained attention in biomedical research as a genetic model for tumor formation. Melanoma development in interspecific hybrids of Xiphophorus is connected to pigment cell specific overexpression of the mutationally activated receptor tyrosine kinase Xmrk. In purebred fish the oncogenic function of xmrk is suppressed by a so far unknown regulator locus R. To test the hypothesis that R is involved in transcriptional regulation of xmrk and consequently acts upstream of the xmrk signal, we performed a quantitative analysis of xmrk transcript levels in normal and melanoma tissues of different Xiphophorus genotypes carrying either a highly tumorigenic or a non-tumorigenic xmrk allele. Our results demonstrate that expression of the tumorigenic xmrk allele is highly increased in malignant melanomas compared to benign lesions, macromelanophore spots, and healthy skin. Transcription of the non-tumorigenic xmrk allele in pigment cells, in contrast, is not influenced by the presence or absence of R. These findings strongly indicate that differential transcriptional regulation of the xmrk promoter determines the tumorigenic potential of xmrk alleles in the Xiphophorus melanoma system, thereby supporting the hypothesis that R suppresses the oncogenic function of xmrk on the level of transcriptional control.
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Affiliation(s)
- Janine Regneri
- Physiological Chemistry I, University of Würzburg, Biocenter, Am Hubland, 97074 Würzburg, Germany
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13
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GUTIÉRREZ MARÍALAURA, GARCÍA GRACIELA. A preliminary linkage map using spotted melanic laboratory strains of the livebearing fish Phalloceros caudimaculatus var. reticulata (Cyprinodontiformes: Poeciliidae). J Genet 2011. [DOI: 10.1007/s12041-011-0085-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Fernandez AA, Garcia R, Paniker L, Trono D, Mitchell DL. An experimental population study of nucleotide excision repair as a risk factor for UVB-induced melanoma. Photochem Photobiol 2011; 87:335-41. [PMID: 21143485 DOI: 10.1111/j.1751-1097.2010.00875.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nucleotide excision repair (NER) is the primary defense against the DNA damage implicit in skin cancer formation and is negatively affected by chronic exposure to UVB radiation. However, in situ and in vitro studies consistently yield equivocal results when addressing individual DNA repair capacity and melanoma susceptibility. The primary objective of this study was to determine if individual global NER capacity is a risk factor for melanoma formation in a prominent UVB-inducible melanoma model, hybrid Xiphophorus fishes. After neonatal UVB irradiation, adult tumor-bearing and tumor-free fish were given a challenge UVB dose and (6-4) photoproduct repair was quantified in individual fish at 24 h using radioimmunoassay. Despite considerable inter-individual variation in repair capacity, ranging from 13% to 91%, we found no difference in mean NER capacity between fish with and without melanomas, thus detaching global NER from melanomagenesis. Furthermore, despite epidemiological data indicating that sex and age are important risk factors underlying melanoma susceptibility, we found no difference in mean NER rates among the sexes or as a function of age. We conclude with a discussion of the apparent paradox of how inter-individual variation in NER is not a risk factor given the clear evidence that DNA damage underlies melanoma susceptibility.
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Affiliation(s)
- André A Fernandez
- Department of Carcinogenesis, University of Texas MD Anderson Cancer Center, Smithville, TX, USA
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15
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Fernandez AA, Bowser PR. Selection for a dominant oncogene and large male size as a risk factor for melanoma in the Xiphophorus animal model. Mol Ecol 2010; 19:3114-23. [PMID: 20618898 DOI: 10.1111/j.1365-294x.2010.04738.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Adult height is a risk factor in numerous human cancers that involve aberrant receptor tyrosine kinase (RTK) signalling. However, its importance is debated due to conflicting epidemiological studies and the lack of useful in vivo models. In Xiphophorus fishes (Platyfishes/Swordtails), a functional RTK, Xiphophorus melanoma receptor kinase (Xmrk), serves as the dominant oncogene and has been maintained for several million years despite being deleterious and in an extremely unstable genomic region. Here we show that the Xmrk genotype is positively correlated with standard length in male and female wild caught Xiphophorus cortezi sampled throughout their phylogeographic distribution. Histopathology confirms the occurrence of malignant melanomas in both sexes; however, melanoma incidence was extremely male biased. Furthermore, males collected with malignant melanomas in the field were significantly larger than both Xmrk males collected without melanomas and wildtype (Xmrk deficient) males. These results not only provide a novel selective mechanism for the persistence of the germline Xmrk oncogene but also create an innovative avenue of melanoma research within the Xiphophorus fishes. Wildlife cancer in natural systems is a growing concern, therefore, future research investigating life history characteristics associated with certain phenotypes and genotypes that predispose an individual to cancer will be fundamental to increasing our understanding of the evolutionary biology of cancer in nature as well as in humans.
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Affiliation(s)
- André A Fernandez
- Department of Carcinogenesis, The University of Texas-M. D. Anderson Cancer Center, Science Park/Research Division, Smithville, TX 78957, USA.
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16
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Belancio VP, Roy-Engel AM, Deininger PL. All y'all need to know 'bout retroelements in cancer. Semin Cancer Biol 2010; 20:200-10. [PMID: 20600922 DOI: 10.1016/j.semcancer.2010.06.001] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 06/14/2010] [Accepted: 06/17/2010] [Indexed: 01/08/2023]
Abstract
Genetic instability is one of the principal hallmarks and causative factors in cancer. Human transposable elements (TE) have been reported to cause human diseases, including several types of cancer through insertional mutagenesis of genes critical for preventing or driving malignant transformation. In addition to retrotransposition-associated mutagenesis, TEs have been found to contribute even more genomic rearrangements through non-allelic homologous recombination. TEs also have the potential to generate a wide range of mutations derivation of which is difficult to directly trace to mobile elements, including double strand breaks that may trigger mutagenic genomic rearrangements. Genome-wide hypomethylation of TE promoters and significantly elevated TE expression in almost all human cancers often accompanied by the loss of critical DNA sensing and repair pathways suggests that the negative impact of mobile elements on genome stability should increase as human tumors evolve. The biological consequences of elevated retroelement expression, such as the rate of their amplification, in human cancers remain obscure, particularly, how this increase translates into disease-relevant mutations. This review is focused on the cellular mechanisms that control human TE-associated mutagenesis in cancer and summarizes the current understanding of TE contribution to genetic instability in human malignancies.
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Affiliation(s)
- Victoria P Belancio
- Tulane University, Department of Structural and Cellular Biology, School of Medicine, Tulane Cancer Center and Tulane Center for Aging, New Orleans, LA 70112, USA
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17
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Zhou Q, Braasch I, Froschauer A, Böhne A, Schultheis C, Schartl M, Volff JN. A novel marker for the platyfish (Xiphophorus maculatus) W chromosome is derived from a Polinton transposon. J Genet Genomics 2010; 37:181-8. [PMID: 20347827 DOI: 10.1016/s1673-8527(09)60036-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 11/13/2009] [Accepted: 11/25/2009] [Indexed: 01/18/2023]
Abstract
A consensus sequence, encoding a putative DNA polymerase type B derived from a Polinton transposon, was assembled from the sex determination region of Xiphophorus maculatus. This predicted protein, which is 1,158 aa in length, contains a DNA_pol_B_2 domain and a DTDS motif. The DNA polymerase type B gene has about 10 copies in the haploid X. maculatus genome with one Y-specific copy. Interestingly, it has specific copies on the W chromosome in the X. maculatus Usumacinta strain (sex determination with female heterogamety), which represent new markers for this type of sex chromosome in platyfish. This marker with W- and Y-specific copies suggests relationship between different types of gonosomes and allows comparing male and female heterogameties in the platyfish. Further molecular analysis of the DNA polymerase type B gene in X. maculatus will shed new light on the evolution of sex chromosomes in platyfish.
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Affiliation(s)
- Qingchun Zhou
- Biofuture Research Group, Physiologische Chemie I, Biozentrum, University of Würzburg, Würzburg 97074, Germany.
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18
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Abstract
Experimental animal models are extremely valuable for the study of human diseases, especially those with underlying genetic components. The exploitation of various animal models, from fruitflies to mice, has led to major advances in our understanding of the etiologies of many diseases, including cancer. Cutaneous malignant melanoma is a form of cancer for which both environmental insult (i.e., UV) and hereditary predisposition are major causative factors. Fish melanoma models have been used in studies of both spontaneous and induced melanoma formation. Genetic hybrids between platyfish and swordtails, different species of the genus Xiphophorus, have been studied since the 1920s to identify genetic determinants of pigmentation and melanoma formation. Recently, transgenesis has been used to develop zebrafish and medaka models for melanoma research. This review will provide a historical perspective on the use of fish models in melanoma research, and an updated summary of current and prospective studies using these unique experimental systems.
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Affiliation(s)
- E Elizabeth Patton
- Institute for Genetics and Molecular Medicine, MRC Human Genetics Unit and Division of Cancer Research, The University of Edinburgh, Edinburgh, UK.
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19
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Fernandez AA. A cancer-causing gene is positively correlated with male aggression in Xiphophorus cortezi. J Evol Biol 2009; 23:386-96. [PMID: 20021547 DOI: 10.1111/j.1420-9101.2009.01914.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The persistence of seemingly maladaptive genes in organisms challenges evolutionary biological thought. In Xiphophorus fishes, certain melanin patterns form malignant melanomas because of a cancer-causing gene (Xiphophorus melanoma receptor kinase; Xmrk), which arose several millions years ago from unequal meiotic recombination. Xiphophorus melanomas are male biased and induced by androgens however male behaviour and Xmrk genotype has not been investigated. This study found that male X. cortezi with the spotted caudal (Sc) pattern, from which melanomas originate, displayed increased aggression in mirror image trials. Furthermore, Xmrk males (regardless of Sc phenotype) bit and performed more agonistic displays than Xmrk deficient males. Male aggressive response decreased when males viewed their Sc image as compared with their non-Sc image. Collectively, these results indicate that Xmrk males experience a competitive advantage over wild-type males and that intrasexual selection could be an important component in the evolutionary maintenance of this oncogene within Xiphophorus.
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Affiliation(s)
- A A Fernandez
- Department of Carcinogenesis, The University of Texas - M. D. Anderson Cancer Center; Science Park/Research Division; Smithville, TX, USA.
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20
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Abstract
Genes that exert their function when they are introduced into a foreign genetic background pose many questions to our current understanding of the forces and mechanisms that promote either the maintenance or divergence of gene functions over evolutionary time. The melanoma inducing Xmrk oncogene of the Southern platyfish (Xiphophorus maculatus) is a stable constituent of the genome of this species. It displays its tumorigenic function, however, almost exclusively only after inter-populational or, even more severely, interspecific hybridization events. The Xiphophorus hybrid melanoma system has gained attention in biomedical research as a genetic model for studying tumor formation. From an evolutionary perspective, a prominent question is: how could this gene persist over millions of years? An attractive hypothesis is that Xmrk, acting as a detrimental gene in a hybrid genome, could be a speciation gene that shields the gene pool of its species from mixing with other closely related sympatric species. In this article, I briefly review our current knowledge of the molecular genetics and biochemical functions of the Xmrk gene and discuss aspects of its evolutionary history and presence with respect to this idea. While Xmrk as a potentially injurious oncogene has clearly survived for millions of years, its role as a speciation gene has to be questioned.
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Affiliation(s)
- Manfred Schartl
- University of Würzburg, Physiologische Chemie I, Theodor-Boveri Institut für Biowissenschaften der Universität Würzburg Am Hubland, 97074 Würzburg.
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21
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Reed LK, LaFlamme BA, Markow TA. Genetic architecture of hybrid male sterility in Drosophila: analysis of intraspecies variation for interspecies isolation. PLoS One 2008; 3:e3076. [PMID: 18728782 PMCID: PMC2517651 DOI: 10.1371/journal.pone.0003076] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 08/07/2008] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND The genetic basis of postzygotic isolation is a central puzzle in evolutionary biology. Evolutionary forces causing hybrid sterility or inviability act on the responsible genes while they still are polymorphic, thus we have to study these traits as they arise, before isolation is complete. METHODOLOGY/PRINCIPAL FINDINGS Isofemale strains of D. mojavensis vary significantly in their production of sterile F(1) sons when females are crossed to D. arizonae males. We took advantage of the intraspecific polymorphism, in a novel design, to perform quantitative trait locus (QTL) mapping analyses directly on F(1) hybrid male sterility itself. We found that the genetic architecture of the polymorphism for hybrid male sterility (HMS) in the F(1) is complex, involving multiple QTL, epistasis, and cytoplasmic effects. CONCLUSIONS/SIGNIFICANCE The role of extensive intraspecific polymorphism, multiple QTL, and epistatic interactions in HMS in this young species pair shows that HMS is arising as a complex trait in this system. Directional selection alone would be unlikely to maintain polymorphism at multiple loci, thus we hypothesize that directional selection is unlikely to be the only evolutionary force influencing postzygotic isolation.
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Affiliation(s)
- Laura K Reed
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, USA.
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22
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Catron DJ, Noor MAF. Gene expression disruptions of organism versus organ in Drosophila species hybrids. PLoS One 2008; 3:e3009. [PMID: 18714377 PMCID: PMC2500191 DOI: 10.1371/journal.pone.0003009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Accepted: 07/31/2008] [Indexed: 01/18/2023] Open
Abstract
Hybrid dysfunctions, such as sterility, may result in part from disruptions in the regulation of gene expression. Studies of hybrids within the Drosophila simulans clade have reported genes expressed above or below the expression observed in their parent species, and such misexpression is associated with male sterility in multigenerational backcross hybrids. However, these studies often examined whole bodies rather than testes or had limited replication using less-sensitive but global techniques. Here, we use a new RNA isolation technique to re-examine hybrid gene expression disruptions in both testes and whole bodies from single Drosophila males by real-time quantitative RT-PCR. We find two early-spermatogenesis transcripts are underexpressed in hybrid whole-bodies but not in assays of testes alone, while two late-spermatogenesis transcripts seem to be underexpressed in both whole-bodies and testes alone. Although the number of transcripts surveyed is limited, these results provide some support for a previous hypothesis that the spermatogenesis pathway in these sterile hybrids may be disrupted sometime after the expression of the early meiotic arrest genes.
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Affiliation(s)
- Daniel J Catron
- Biology Department, Duke University, Durham, North Carolina, United States of America
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23
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Literature watch. Xiphophorus. Zebrafish 2008; 3:105-10. [PMID: 18248251 DOI: 10.1089/zeb.2006.3.105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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24
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Bolnick DI, Turelli M, López-Fernández H, Wainwright PC, Near TJ. Accelerated mitochondrial evolution and "Darwin's corollary": asymmetric viability of reciprocal F1 hybrids in Centrarchid fishes. Genetics 2008; 178:1037-48. [PMID: 18245356 PMCID: PMC2248366 DOI: 10.1534/genetics.107.081364] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2007] [Accepted: 11/26/2007] [Indexed: 11/18/2022] Open
Abstract
Reciprocal crosses between species can yield hybrids with different viabilities. The high frequency of this asymmetric hybrid viability ("Darwin's corollary") places it alongside Haldane's rule and the "large-X effect" as a general feature of postmating reproductive isolation. Recent theory suggests that reciprocal cross asymmetries can arise from stochastic substitutions in uniparentally inherited loci such as mitochondrial genomes, although large systematic differences in mitochondrial substitution rates can also contribute to asymmetries. Although the magnitude of asymmetry will be relatively insensitive to unequal rates of mitochondrial evolution in diverging species, we show here that rate asymmetries can have a large effect on the direction of viability asymmetries. In reciprocal crosses between species, the maternal parent with faster mitochondrial evolution will tend to produce less viable F(1) hybrids owing to an increased probability of mito-nuclear incompatibilities. We test this prediction using data on reciprocal hybrid viability and molecular evolution rates from a clade of freshwater fishes, Centrarchidae. As predicted, species with accelerated mitochondrial evolution tend to be the worse maternal parent for F(1) hybrids, providing the first comparative evidence for a systematic basis to Darwin's corollary. This result is consistent with the hypothesis that mito-nuclear incompatibilities can play an important role in reproductive isolation. Such asymmetrical reproductive isolation may help explain the asymmetrical mitochondrial introgression observed between many hybridizing species. However, as with any comparative study, we cannot rule out the possibility that our results arise from a mutual correlation with a third variable such as body size.
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Affiliation(s)
- Daniel I Bolnick
- Section of Integrative Biology, University of Texas, Austin, Texas 78712, USA.
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25
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Amatruda JF, Patton EE. Chapter 1 Genetic Models of Cancer in Zebrafish. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 271:1-34. [DOI: 10.1016/s1937-6448(08)01201-x] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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26
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Selz Y, Braasch I, Hoffmann C, Schmidt C, Schultheis C, Schartl M, Volff JN. Evolution of melanocortin receptors in teleost fish: The melanocortin type 1 receptor. Gene 2007; 401:114-22. [PMID: 17707598 DOI: 10.1016/j.gene.2007.07.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 07/04/2007] [Accepted: 07/04/2007] [Indexed: 11/17/2022]
Abstract
The melanocortin type 1 receptor (Mc1r) belongs to a family of G-protein-coupled receptors involved in various physiological processes in vertebrates. Melanocortins, the Mcr natural agonists, are pituitary peptide hormones including adrenocorticotropin and melanocyte-stimulating hormones. In mammals and birds, Mc1r is involved in pigmentation and expressed in melanocytes and melanoma. Activation of Mc1r leads to eumelanin production as well as to proliferation and survival of melanocytes in the epidermis. Here we report the molecular and evolutionary analysis of mc1r from three major fish models, the zebrafish Danio rerio, the medaka Oryzias latipes and the platyfish Xiphophorus maculatus. In contrast to some other melanocortin receptor genes, mc1r has been conserved as a single copy gene in divergent fish species. Its expression was detected in all organs tested in platyfish and medaka but was restricted to eyes, skin, brain and testis in zebrafish, this possibly reflecting differences in the distribution of extracutaneous melanophores. The mc1r gene was found to be expressed during embryogenesis, as well as in Xiphophorus hybrid melanoma, similar to human tumours. Protein sequence comparison between fish and mammalian Mc1r revealed a remarkable concordance between evolutionary and functional analyses for the identification of residues and regions critical for receptor function.
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MESH Headings
- Amino Acid Sequence
- Amino Acid Substitution
- Animals
- Cell Line
- Cloning, Molecular
- Cyprinodontiformes/genetics
- Evolution, Molecular
- Gene Dosage
- Melanocortins/agonists
- Melanocortins/genetics
- Melanocortins/metabolism
- Melanoma, Experimental
- Melanophores/metabolism
- Models, Genetic
- Molecular Sequence Data
- Oryzias/genetics
- Phylogeny
- Protein Structure, Tertiary
- Receptor, Melanocortin, Type 1/chemistry
- Receptor, Melanocortin, Type 1/genetics
- Receptor, Melanocortin, Type 1/metabolism
- Sequence Analysis, Protein
- Sequence Homology, Amino Acid
- Zebrafish/genetics
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Affiliation(s)
- Yvonne Selz
- University of Würzburg, Institute of Physiological Chemistry I, Biozentrum, Am Hubland, D-97074 Würzburg, Germany
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27
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Gutiérrez ML, García G. Inheritance of a Dominant Spotted Melanic Mutation in the Livebearing Fish Phalloceros caudimaculatus var. reticulata from "Banados del Este" Reserve of Biosphere Site in Uruguay. CYTOLOGIA 2007. [DOI: 10.1508/cytologia.72.131] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- María Laura Gutiérrez
- Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la Republica (Udelar), Uruguay
| | - Graciela García
- Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la Republica (Udelar), Uruguay
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28
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Ortíz-Barrientos D, Counterman BA, Noor MAF. Gene expression divergence and the origin of hybrid dysfunctions. Genetica 2006; 129:71-81. [PMID: 17043744 DOI: 10.1007/s10709-006-0034-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2004] [Accepted: 06/20/2005] [Indexed: 10/24/2022]
Abstract
Hybrids between closely related species are often sterile or inviable as a consequence of failed interactions between alleles from the different species. Most genetic studies have focused on localizing the alleles associated with these failed interactions, but the mechanistic/biochemical nature of the failed interactions is poorly understood. This review discusses recent studies that may contribute to our understanding of these failed interactions. We focus on the possible contribution of failures in gene expression as an important contributor to hybrid dysfunctions. Although regulatory pathways that share elements in highly divergent taxa may contribute to hybrid dysfunction, various studies suggest that misexpression may be disproportionately great in regulatory pathways containing rapidly evolving, particularly male-biased, genes. We describe three systems that have been analyzed recently with respect to global patterns of gene expression in hybrids versus pure species, each in Drosophila. These studies reveal that quantitative misexpression of genes is associated with hybrid dysfunction. Misexpression of genes has been documented in sterile hybrids relative to pure species, and variation in upstream factors may sometimes cause the over- or under-expression of genes resulting in hybrid sterility or inviability. Studying patterns of evolution between species in regulatory pathways, such as spermatogenesis, should help in identifying which genes are more likely to be contributors to hybrid dysfunction. Ultimately, we hope more functional genetic studies will complement our understanding of the genetic disruptions leading to hybrid dysfunctions and their role in the origin of species.
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29
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Schultheis C, Zhou Q, Froschauer A, Nanda I, Selz Y, Schmidt C, Matschl S, Wenning M, Veith AM, Naciri M, Hanel R, Braasch I, Dettai A, Böhne A, Ozouf-Costaz C, Chilmonczyk S, Ségurens B, Couloux A, Bernard-Samain S, Schmid M, Schartl M, Volff JN. Molecular Analysis of the Sex-Determining Region of the PlatyfishXiphophorus maculatus. Zebrafish 2006; 3:299-309. [DOI: 10.1089/zeb.2006.3.299] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
| | - Qingchun Zhou
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
- Present address: Department of Zoology and Stephenson Research and Technology Center, University of Oklahoma, Norman, Oklahoma
| | - Alexander Froschauer
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
- Present address: Institut für Zoologie, Technische Universität Dresden, Dresden, Germany
| | - Indrajit Nanda
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Yvonne Selz
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
| | - Cornelia Schmidt
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
| | - Sabine Matschl
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
| | - Marina Wenning
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
| | - Anne-Marie Veith
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
| | - Mariam Naciri
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
- Present address: Université Mohamed V, Faculté des Sciences, Rabat, Morocco
| | - Reinhold Hanel
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
- Present address: Leibniz Institut für Meereswissenschaften, IFM-GEOMAR, Kiel, Germany
| | - Ingo Braasch
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
| | - Agnès Dettai
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
- Département Systématique et Evolution, Muséum National d'Histoire Naturelle, Paris, France
| | - Astrid Böhne
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
| | - Catherine Ozouf-Costaz
- Département Systématique et Evolution, Muséum National d'Histoire Naturelle, Paris, France
| | - Stefan Chilmonczyk
- Laboratoire de Virologie et Immunologie Molécularies, INRA, Jouy en Josas, France
| | | | - Arnaud Couloux
- Genoscope/Centre National de Séquençage, CNRS-UMR, Evry, France
| | | | - Michael Schmid
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Manfred Schartl
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
| | - Jean-Nicolas Volff
- Physiologische Chemie I, Biozentrum , University of Würzburg, Würzburg, Germany
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30
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Barnes D, Dowell L, Forest D, Parton A, Pavicevic P, Kazianis S. Characterization of XM, a NovelXiphophorusMelanoma-Derived Cell Line. Zebrafish 2006; 3:371-81. [DOI: 10.1089/zeb.2006.3.371] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- David Barnes
- Mount Desert Island Biological Laboratory, Salsbury Cove, Maine
| | - Lori Dowell
- Mount Desert Island Biological Laboratory, Salsbury Cove, Maine
| | - David Forest
- Mount Desert Island Biological Laboratory, Salsbury Cove, Maine
| | - Angela Parton
- Mount Desert Island Biological Laboratory, Salsbury Cove, Maine
| | - Peter Pavicevic
- Mount Desert Island Biological Laboratory, Salsbury Cove, Maine
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31
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Johnson NA, Porter AH. Evolution of branched regulatory genetic pathways: directional selection on pleiotropic loci accelerates developmental system drift. Genetica 2006; 129:57-70. [PMID: 16912839 DOI: 10.1007/s10709-006-0033-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Accepted: 01/01/2006] [Indexed: 10/24/2022]
Abstract
Developmental systems are regulated by a web of interacting loci. One common and useful approach in studying the evolution of development is to focus on classes of interacting elements within these systems. Here, we use individual-based simulations to study the evolution of traits controlled by branched developmental pathways involving three loci, where one locus regulates two different traits. We examined the system under a variety of selective regimes. In the case where one branch was under stabilizing selection and the other under directional selection, we observed "developmental system drift": the trait under stabilizing selection showed little phenotypic change even though the loci underlying that trait showed considerable evolutionary divergence. This occurs because the pleiotropic locus responds to directional selection and compensatory mutants are then favored in the pathway under stabilizing selection. Though developmental system drift may be caused by other mechanisms, it seems likely that it is accelerated by the same underlying genetic mechanism as that producing the Dobzhansky-Muller incompatibilities that lead to speciation in both linear and branched pathways. We also discuss predictions of our model for developmental system drift and how different selective regimes affect probabilities of speciation in the branched pathway system.
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Affiliation(s)
- Norman A Johnson
- Department of Plant, Soil & Insect Sciences, & Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA 01003, USA.
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32
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Shuker DM, Underwood K, King TM, Butlin RK. Patterns of male sterility in a grasshopper hybrid zone imply accumulation of hybrid incompatibilities without selection. Proc Biol Sci 2006; 272:2491-7. [PMID: 16271974 PMCID: PMC1599774 DOI: 10.1098/rspb.2005.3242] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
It is now widely accepted that post-zygotic reproductive isolation is the result of negative epistatic interactions between derived alleles fixed independently at different loci in diverging populations (the Dobzhansky-Muller model). What is less clear is the nature of the loci involved and whether the derived alleles increase in frequency through genetic drift, or as a result of natural or sexual selection. If incompatible alleles are fixed by selection, transient polymorphisms will be rare and clines for these alleles will be steep where divergent populations meet. If they evolve by drift, populations are expected to harbour substantial genetic variation in compatibility and alleles will introgress across hybrid zones once they recombine onto a genetic background with which they are compatible. Here we show that variation in male sterility in a naturally occurring Chorthippus parallelus grasshopper hybrid zone conforms to the neutral expectations. Asymmetrical clines for male sterility have long tails of introgression and populations distant from the zone centre show significant genetic variation for compatibility. Our data contrast with recent observations on 'speciation genes' that have diverged as a result of strong natural selection.
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Affiliation(s)
- David M Shuker
- The University of Leeds School of Biology Leeds LS2 9JT, UK.
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33
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Abstract
The last few decades have seen a surge of interest in speciation, the genetic changes underlying it, and the evolutionary forces driving it. As with most disciplines, however, the nature of the questions addressed has changed with time. Many studies from the 1980s and 1990s often asked questions about whether certain processeseveroccur in nature (e.g., speciation with gene flow). Since that time, case studies have provided evidence that nearly all evolutionary processes thought to be involved in speciation have occurred at least once. As a result, we are now in a new era where the "big questions" must go beyond demonstrations that a phenomenon has happened at least once. Here we discuss a few open questions in speciation—questions that we feel are not only exciting but tractable. We focus our discussion most sharply on recent studies inDrosophilaand related species, the area of our expertise. However, we also emphasize the importance of broad taxonomic meta-analyses testing the importance or frequency of various processes thought to cause speciation.
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Affiliation(s)
| | - Jerry A. Coyne
- Department of Ecology and Evolution, University of Chicago
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34
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Woolcock B, Kazianis S, Lucito R, Walter R, Kallman K, Morizot D, Vielkind J. Allele-Specific Marker Generation and Linkage Mapping on theXiphophorusSex Chromosomes. Zebrafish 2006; 3:23-37. [DOI: 10.1089/zeb.2006.3.23] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- B. Woolcock
- British Columbia Cancer Research Centre, Vancouver, British Columbia, Canada
| | - S. Kazianis
- The Wistar Institute, Program of Molecular and Cellular Oncogenesis, Philadelphia, Pennsylvania
| | - R. Lucito
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York
| | - R.B. Walter
- Molecular Biosciences Research Group, Department of Chemistry and Biochemistry, Texas State University, San Marco, Texas
| | - K.D. Kallman
- Division of Vertebrate Zoology (Ichthyology), American Museum of Natural History, New York, New York
| | - D.C. Morizot
- Science Park Research Division, MD Anderson Cancer Center, Smithville, Texas
| | - J.R. Vielkind
- British Columbia Cancer Research Centre, Vancouver, British Columbia, Canada
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35
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Zhou Q, Froschauer A, Schultheis C, Schmidt C, Bienert GP, Wenning M, Dettai A, Volff JN. Helitron Transposons on the Sex Chromosomes of the PlatyfishXiphophorus maculatusand Their Evolution in Animal Genomes. Zebrafish 2006; 3:39-52. [DOI: 10.1089/zeb.2006.3.39] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Affiliation(s)
- Qingchun Zhou
- Biofuture Research Group, Physiologische Chemie I, Biozentrum, University of Würzburg, Würzburg, Germany
- Present address: Department of Zoology and Stephenson Research & Technology Center, University of Oklahoma, Norman, Oklahoma
| | - Alexander Froschauer
- Biofuture Research Group, Physiologische Chemie I, Biozentrum, University of Würzburg, Würzburg, Germany
- Present address: Institut für Zoologie, Technische Universität Dresden, Dresden, Germany
| | - Christina Schultheis
- Biofuture Research Group, Physiologische Chemie I, Biozentrum, University of Würzburg, Würzburg, Germany
| | - Cornelia Schmidt
- Biofuture Research Group, Physiologische Chemie I, Biozentrum, University of Würzburg, Würzburg, Germany
| | - Gerd P. Bienert
- Biofuture Research Group, Physiologische Chemie I, Biozentrum, University of Würzburg, Würzburg, Germany
| | - Marina Wenning
- Biofuture Research Group, Physiologische Chemie I, Biozentrum, University of Würzburg, Würzburg, Germany
| | - Agnès Dettai
- Biofuture Research Group, Physiologische Chemie I, Biozentrum, University of Würzburg, Würzburg, Germany
- Present address: Département Systématique et Evolution, Muséum National d'Histoire Naturelle, Paris, France
| | - Jean-Nicolas Volff
- Biofuture Research Group, Physiologische Chemie I, Biozentrum, University of Würzburg, Würzburg, Germany
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Berghmans S, Jette C, Langenau D, Hsu K, Stewart R, Look T, Kanki JP. Making waves in cancer research: new models in the zebrafish. Biotechniques 2005; 39:227-37. [PMID: 16116796 DOI: 10.2144/05392rv02] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The zebrafish (Danio rerio) has proven to be a powerful vertebrate model system for the genetic analysis of developmental pathways and is only beginning to be exploited as a model for human disease and clinical research. The attributes that have led to the emergence of the zebrafish as a preeminent embryological model, including its capacity for forward and reverse genetic analyses, provides a unique opportunity to uncover novel insights into the molecular genetics of cancer. Some of the advantages of the zebrafish animal model system include fecundity, with each female capable of laying 200-300 eggs per week, external fertilization that permits manipulation of embryos ex utero, and rapid development of optically clear embryos, which allows the direct observation of developing internal organs and tissues in vivo. The zebrafish is amenable to transgenic and both forward and reverse genetic strategies that can be used to identify or generate zebrafish models of different types of cancer and may also present significant advantages for the discovery of tumor suppressor genes that promote tumorigenesis when mutationally inactivated. Importantly, the transparency and accessibility of the zebrafish embryo allows the unprecedented direct analysis of pathologic processes in vivo, including neoplastic cell transformation and tumorigenic progression. Ultimately, high-throughput modifier screens based on zebrafish cancer models can lead to the identification of chemicals or genes involved in the suppression or prevention of the malignant phenotype. The identification of small molecules or gene products through such screens will serve as ideal entry points for novel drug development for the treatment of cancer. This review focuses on the current technology that takes advantage of the zebrafish model system to further our understanding of the genetic basis of cancer and its treatment.
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Orr HA. The genetic basis of reproductive isolation: insights from Drosophila. Proc Natl Acad Sci U S A 2005; 102 Suppl 1:6522-6. [PMID: 15851676 PMCID: PMC1131866 DOI: 10.1073/pnas.0501893102] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent studies of the genetics of speciation in Drosophila have focused on two problems: (i) identifying and characterizing the genes that cause reproductive isolation, and (ii) determining the evolutionary forces that drove the divergence of these "speciation genes." Here, I review this work. I conclude that speciation genes correspond to ordinary loci having normal functions within species. These genes fall into several functional classes, although a role in transcriptional regulation could prove particularly common. More important, speciation genes are typically very rapidly evolving, and this divergence is often driven by positive Darwinian selection. Finally, I review recent work in Drosophila pseudoobscura on the possible role of meiotic drive in the evolution of the genes that cause postzygotic isolation.
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Affiliation(s)
- H Allen Orr
- Department of Biology, University of Rochester, NY 14627, USA.
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Abstract
Similar to higher vertebrates, neoplasia is not an uncommon disease in fishes, which are the largest group of vertebrates. However,neoplasia in fishes is generally a benign condition with relatively few exceptions of malignant disease. The objective of this discussion is to provide an overview of neoplasia and the various neoplastic disease conditions in fishes according to organ system,including the few neoplasms of species that are familiar to the aquatic animal or exotic animal practitioner. The discussion also considers the various nonneoplastic lesions in fishes that may be confused with neoplasms, and treatment of neoplastic disease in fishes that is generally restricted to surgical intervention.
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Affiliation(s)
- Joseph M Groff
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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Meierjohann S, Schartl M, Volff JN. Genetic, biochemical and evolutionary facets of Xmrk-induced melanoma formation in the fish Xiphophorus. Comp Biochem Physiol C Toxicol Pharmacol 2004; 138:281-9. [PMID: 15533786 DOI: 10.1016/j.cca.2004.06.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2004] [Revised: 05/26/2004] [Accepted: 06/16/2004] [Indexed: 12/11/2022]
Abstract
Certain interspecific hybrids of the fish Xiphophorus spontaneously develop melanoma induced by the derepression of the Xmrk oncogene. Xmrk is a recent duplicate of an orthologue of the mammalian epidermal growth factor receptor gene Egfr. In addition to a specific overexpression in melanoma, amino-acid substitutions in the extracellular domain leading to ligand-independent dimerisation and constitutive autophosphorylation are responsible for the tumorigenic potential of Xmrk. The Xmrk receptor induces several signal transduction pathways mediating cell proliferation and resistance to apoptosis and initiating dedifferentiation. Moreover, Xmrk upregulates the expression of the secreted protein osteopontin, inducing an autocrine loop possibly allowing invasion and survival in the dermis as a first step in malignancy. Hence, Xmrk is able to induce pathways essential for a transformed phenotype. Some of these events are equivalent to those found downstream of the mammalian Egfr, but others have clearly evolved differently or are specific for pigment cells. Xmrk is potentially hazardous, nonessential and located in a very unstable genomic region. Nevertheless, Xmrk has been maintained under purifying selection in divergent Xiphophorus species. Hence, Xmrk has probably a beneficial function under certain conditions. The analysis of this function is a major challenge for future research in the Xiphophorus model.
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Affiliation(s)
- Svenja Meierjohann
- Physiologische Chemie I, Biozentrum, University of Würzburg, am Hubland, D-97074 Würzburg, Germany
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Noor MAF, Michalak P, Donze D. Characterization of a male-predominant antisense transcript underexpressed in hybrids of Drosophila pseudoobscura and D. persimilis. Genetics 2004; 165:1823-30. [PMID: 14704168 PMCID: PMC1462881 DOI: 10.1093/genetics/165.4.1823] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Characterizing genes that are misregulated in hybrids may elucidate the genetic basis of hybrid sterility or other hybrid dysfunctions that contribute to speciation. Previously, a small segment of a male-predominant transcript that is underexpressed in adult male hybrids of Drosophila pseudoobscura and D. persimilis relative to pure species was identified in a differential display screen. Here, we obtained the full sequence of this 1330-bp transcript and determined that it is an antisense message with high sequence similarity to the D. melanogaster TRAP100 gene, part of the Mediator protein complex that regulates transcriptional initiation during development. Both the sense and the antisense messages are transcribed in D. pseudoobscura, but only the sense message (TRAP100) is transcribed in D. melanogaster complex species. Unlike the antisense message, the sense message is transcribed similarly in D. pseudoobscura males and females and in hybrids of D. pseudoobscura and D. persimilis. The high sequence similarity between distantly related species suggests that the sense message is functionally constrained within the genus. We speculate that the antisense transcript may have evolved a role in male-specific post-transcriptional regulation of TRAP100 in the D. pseudoobscura lineage and that its underexpression in sterile hybrid males may cause an overproduction of TRAP100 protein, possibly yielding deleterious effects.
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Affiliation(s)
- Mohamed A F Noor
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
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Volff JN, Körting C, Froschauer A, Zhou Q, Wilde B, Schultheis C, Selz Y, Sweeney K, Duschl J, Wichert K, Altschmied J, Schartl M. The xmrk oncogene can escape nonfunctionalization in a highly unstable subtelomeric region of the genome of the fish xiphophorus☆. Genomics 2003; 82:470-9. [PMID: 13679027 DOI: 10.1016/s0888-7543(03)00168-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The Xmrk oncogene involved in melanoma formation in the fish Xiphophorus was formed relatively recently by duplication of the epidermal growth factor co-orthologue egfrb. In the platyfish X. maculatus, Xmrk is located close to the major sex-determining locus in a subtelomeric region of the X and Y sex chromosomes that frequently undergoes duplications and other rearrangements. This region accumulates repetitive sequences: more than 80% of the 33-kb region 3' of Xmrk is constituted by retrotransposable elements. The high degree of nucleotide identity between X- and Y-linked sequences and the rarity of gonosome-specific rearrangements indicated that the instability observed was not a manifestation of gonosome-specific degeneration. Seven other duplicated genes were found, all corresponding, in contrast to Xmrk, to pseudogenes (nonfunctionalization). Functional persistence of Xmrk in a highly unstable region in divergent Xiphophorus species suggests a beneficial function under certain conditions for this dispensable and potentially injurious gene.
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Affiliation(s)
- Jean-Nicolas Volff
- Physiologische Chemie I, Biozentrum der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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Volff JN, Schartl M. Evolution of signal transduction by gene and genome duplication in fish. JOURNAL OF STRUCTURAL AND FUNCTIONAL GENOMICS 2003; 3:139-50. [PMID: 12836693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
Fishes possess more genes encoding receptor tyrosine kinases from the epidermal growth factor receptor (EGFR) family than other organisms. Three of the four genes present in higher vertebrates have been duplicated early during the evolution of the ray-finned fish lineage possibly as a consequence of an event of whole genome duplication. In the fish Xiphophorus, a much more recent local event of gene duplication of the egfr co-orthologue egfr-b generated a eighth gene, the Xmrk oncogene. This duplicate acquired within a short time a constitutive activity and a pigment cell-specific overexpression responsible for the induction of melanoma in certain interspecific hybrids. Despite its frequent loss during evolution of the genus Xiphophorus, the maintenance of Xmrk in numerous species and its evolution under purifying selection suggest a so far unknown function under certain natural conditions. One of the known functions of Xmrk in tumor cells is the suppression of differentiation of melanocytes induced by the microphthalmia-associated transcription factor MITF. While only one gene with alternative 5' exons and promoters is present in higher vertebrates, two mitf genes were identified in fish. Subfunctionalization of mitf paralogues by differential degeneration of alternative exons and regulatory sequences led particularly to the formation of a mitf gene specifically expressed in the melanocyte lineage. These observations validate fish as an outstanding model to study the mechanisms and biological consequences of gene and genome duplication but underline the complexity of the fish model and the caution necessary in transferring knowledge from fish to higher vertebrates and vice versa.
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Affiliation(s)
- Jean-Nicolas Volff
- Physiologische Chemie I, Biofuture Research Group 'Evolutionary Fish Genomics', Biozentrum, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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Reiland J, Noor MAF. Little qualitative RNA misexpression in sterile male F1 hybrids of Drosophila pseudoobscura and D. persimilis. BMC Evol Biol 2002; 2:16. [PMID: 12223116 PMCID: PMC126258 DOI: 10.1186/1471-2148-2-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2002] [Accepted: 09/10/2002] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Although the genetics of hybrid sterility has been the subject of evolutionary studies for over sixty years, no one has shown the reason(s) why alleles that operate normally within species fail to function in another genetic background. Several lines of evidence suggest that failures in normal gene transcription contribute to hybrid dysfunctions, but genome-wide studies of gene expression in pure-species and hybrids have not been undertaken. Here, we study genome-wide patterns of expression in Drosophila pseudoobscura, D. persimilis, and their sterile F1 hybrid males using differential display. RESULTS Over five thousand amplifications were analyzed, and 3312 were present in amplifications from both of the pure species. Of these, 28 (0.5%) were not present in amplifications from adult F1 hybrid males. Using product-specific primers, we were able to confirm one of nine of the transcripts putatively misexpressed in hybrids. This transcript was shown to be male-specific, but without detectable homology to D. melanogaster sequence. CONCLUSION We tentatively conclude that hybrid sterility can evolve without widespread, qualitative misexpression of transcripts in species hybrids. We suggest that, if more misexpression exists in sterile hybrids, it is likely to be quantitative, tissue-specific, and/ or limited to earlier developmental stages. Although several caveats apply, this study was a first attempt to determine the mechanistic basis of hybrid sterility, and one potential candidate gene has been identified for further study.
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Affiliation(s)
- Jane Reiland
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Mohamed AF Noor
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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Froschauer A, Körting C, Katagiri T, Aoki T, Asakawa S, Shimizu N, Schartl M, Volff JN. Construction and initial analysis of bacterial artificial chromosome (BAC) contigs from the sex-determining region of the platyfish Xiphophorus maculatus. Gene 2002; 295:247-54. [PMID: 12354660 DOI: 10.1016/s0378-1119(02)00684-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Despite the major importance of sex determination in aquaculture, no master sex-determining gene has been identified so far in teleost fish. In the platyfish Xiphophorus maculatus, this master gene is flanked by two receptor tyrosine kinase genes, the Xmrk oncogene responsible for melanoma formation in some Xiphophorus interspecific hybrids, and its proto-oncogenic counterpart. Both Xmrk genes, which have already been characterised at the molecular level, delimit a region of about 1 Mb that contains other gene loci involved in sexual maturity, pigmentation and melanoma formation. We have constructed a genomic bacterial artificial chromosome (BAC) library of X. maculatus with a tenfold coverage of the haploid genome and walked on both X and Y sex chromosomes starting from both Xmrk genes. This led to the assembly of BAC contigs from the sex-determining region covering approximately 950 kb of the X and 750 kb of the Y chromosome. To our knowledge, these are the largest contigs reported so far for sex chromosomes in fish. Molecular analysis suggests that the sex-determining region of X. maculatus frequently undergoes retrotranspositions and other kinds of rearrangements. This genomic plasticity might be related to the high genetic variability observed in Xiphophorus for sex determination, sexual maturity, pigmentation and melanoma formation, which are encoded by gene loci located in the sex-determining region.
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Affiliation(s)
- Alexander Froschauer
- Lehrstuhl Physiologische Chemie I, Biozentrum, University of Würzburg, Am Hubland, D-97074, Würzburg, Germany
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Abstract
Poeciliids are one of the best-studied groups of fishes with respect to sex determination. They present an amazing variety of mechanisms, which span from simple XX-XY or ZZ-ZW systems to polyfactorial sex determination. The gonosomes of poeciliids generally are homomorphic, but very early stages of sex chromosome differentiation have been occasionally detected in some species. In the platyfish Xiphophorus maculatus, gene loci involved in melanoma formation, in different pigmentation patterns and in sexual maturity are closely linked to the sex-determining locus in the subtelomeric region of the X- and Y- chromosomes. The majority of traits encoded by these loci are highly polymorphic. This phenomenon might be explained by the high level of genomic plasticity apparently affecting the sex-determining region, where frequent rearrangements such as duplications, deletions, amplifications, and transpositions frequently occur. We propose that the high plasticity of the sex-determining region might explain the variability of sex determination in Xiphophorus and other poeciliids.
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Affiliation(s)
- J N Volff
- Physiologische Chemie I, Biozentrum der Universität Würzburg, Germany.
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Seckinger J, Brinkmann H, Meyer A. Microsatellites in the genus Xiphophorus, developed in Xiphophorus montezumae. ACTA ACUST UNITED AC 2002. [DOI: 10.1046/j.1471-8286.2002.00124.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Fishes of the genus Xiphophorus (platyfishes and swordtails) are small, internally fertilizing, livebearing, and derived from freshwater habitats in Mexico, Guatemala, Belize, and Honduras. Scientists have used these fishes in cancer research studies for more than 70 yr. The genus is presently composed of 22 species that are quite divergent in their external morphology. Most cancer studies using Xiphophorus use hybrids, which can be easily produced by artificial insemination. Phenotypic traits, such as macromelanophore pigment patterns, are often drastically altered as a result of lack of gene regulation within hybrid fishes. These fish can develop large exophytic melanomas as a result of upregulated expression of these pigment patterns. Because backcross hybrid fish are susceptible to the development of melanoma and other neoplasms, they can be subjected to potentially deleterious chemical and physical agents. It is thus possible to use gene mapping and cloning methodologies to identify and characterize oncogenes and tumor suppressors implicated in spontaneous or induced neoplasia. This article reviews the history of cancer research using Xiphophorus and recent developments regarding DNA repair capabilities, mapping, and cloning of candidate genes involved in neoplastic phenotypes. The particular genetic complexity of melanoma in these fishes is analyzed and reviewed.
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Affiliation(s)
- R B Walter
- Department of Chemistry and Biochemistry, Southwest Texas State University (SWTSU), San Marcos, Texas, USA
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Volff JN, Körting C, Altschmied J, Duschl J, Sweeney K, Wichert K, Froschauer A, Schartl M. Jule from the fish Xiphophorus is the first complete vertebrate Ty3/Gypsy retrotransposon from the Mag family. Mol Biol Evol 2001; 18:101-11. [PMID: 11158369 DOI: 10.1093/oxfordjournals.molbev.a003784] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Jule is the second complete long-terminal-repeat (LTR) Ty3/Gypsy retrotransposon identified to date in vertebrates. Jule, first isolated from the poeciliid fish Xiphophorus maculatus, is 4.8 kb in length, is flanked by two 202-bp LTRs, and encodes Gag (structural core protein) and Pol (protease, reverse transcriptase, RNase H, and integrase, in that order) but no envelope. There are three to four copies of Jule per haploid genome in X. maculatus. Two of them are located in a subtelomeric region of the sex chromosomes, where they are associated with the Xmrk receptor tyrosine kinase genes, of which oncogenic versions are responsible for the formation of hereditary melanoma in Xiphophorus. One almost intact copy of Jule was found in the first intron of the X-chromosomal allele of the Xmrk proto-oncogene, and a second, more corrupted copy is present only 56 nt downstream of the polyadenylation signal of the Xmrk oncogene. Jule-related elements were detected by Southern blot hybridization with less than 10 copies per haploid genome in numerous other poeciliids, as well as in more divergent fishes, including the medakafish Oryzias latipes and the tilapia Oreochromis niloticus. Database searches also identified Jule-related sequences in the zebrafish Danio rerio and in both genome project pufferfishes, Fugu rubripes and Tetraodon nigroviridis. Phylogenetic analysis revealed that Jule is the first member of the Mag family of Ty3/Gypsy retrotransposons described to date in vertebrates. This family includes the silkworm Mag and sea urchin SURL retrotransposons, as well as sequences from the nematode Caenorhabditis elegans. Additional related elements were identified in the genomes of the malaria mosquito Anopheles gambiae and the nematode Ascaris lumbricoides. Phylogeny of Mag-related elements suggested that the Mag family of retrotransposons is polyphyletic and is constituted of several ancient lineages that diverged before their host genomes more than 600 MYA.
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Affiliation(s)
- J N Volff
- Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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Abstract
New species arise as reproductive isolation evolves between diverging populations. Here we review recent work in the genetics of postzygotic reproductive isolation-the sterility and inviability of species hybrids. Over the last few years, research has taken two new directions. First, we have begun to learn a good deal about the population genetic forces driving the evolution of postzygotic isolation. It has, for instance, become increasingly clear that conflict-driven processes, like sexual selection and meiotic drive, may contribute to the evolution of hybrid sterility. Second, we have begun to learn something about the identity and molecular characteristics of the actual genes causing hybrid problems. Although molecular genetic data are limited, early findings suggest that "speciation genes" correspond to loci having normal functions within species and that these loci sometimes diverge as a consequence of evolution in gene regulation.
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Affiliation(s)
- H A Orr
- Department of Biology, University of Rochester, Rochester, New York 14627, USA
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Volff JN, Körting C, Schartl M. Multiple lineages of the non-LTR retrotransposon Rex1 with varying success in invading fish genomes. Mol Biol Evol 2000; 17:1673-84. [PMID: 11070055 DOI: 10.1093/oxfordjournals.molbev.a026266] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Rex1, together with the related BABAR: elements, represents a new family of non-long-terminal-repeat (non-LTR) retrotransposons from fish, which might be related to the CR1 clade of LINE elements. Rex1/BABAR: retrotransposons encode a reverse transcriptase and an apurinic/apyrimidinic endonuclease, which is very frequently removed by incomplete reverse transcription. Different Rex1 elements show a conserved terminal 3' untranslated region followed by oligonucleotide tandem repeats of variable size and sequence. Phylogenetic analysis revealed that Rex1 retrotransposons were frequently active during fish evolution. They formed multiple ancient lineages, which underwent several independent and recent bursts of retrotransposition and invaded fish genomes with varying success (from <5 to 500 copies per haploid genome). At least three of these ancient Rex1 lineages were detected within the genome of poeciliids. One lineage is absent from some poeciliids but underwent successive rounds of retrotransposition in others, thereby increasing its copy number from <10 to about 200. At least three ancient Rex1 lineages were also detected in the genome project fish Fugu rubripes. Rex1 distribution within one of its major lineages is discontinuous: Rex1 was found in all Acanthopterygii (common ancestor in the main teleost lineage approximately 90 MYA) and in both European and Japanese eels (divergence from the main teleost lineage about 180 MYA) but not in trout, pike, carp, and zebrafish (divergence 100-120 MYA). This might either result from frequent loss or rapid divergence of Rex1 elements specifically in some fish lineages or represent one of the very rare examples of horizontal transfer of non-LTR retrotransposons. This analysis highlights the dynamics and complexity of retrotransposon evolution and the variability of the impact of retrotransposons on vertebrate genomes.
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Affiliation(s)
- J N Volff
- Physiological Chemistry I, Biocenter, University of Würzburg, Würzburg, Germany.
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