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Shen Y, Chalopin D, Garcia T, Boswell M, Boswell W, Shiryev SA, Agarwala R, Volff JN, Postlethwait JH, Schartl M, Minx P, Warren WC, Walter RB. X. couchianus and X. hellerii genome models provide genomic variation insight among Xiphophorus species. BMC Genomics 2016; 17:37. [PMID: 26742787 PMCID: PMC4705583 DOI: 10.1186/s12864-015-2361-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 12/30/2015] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Xiphophorus fishes are represented by 26 live-bearing species of tropical fish that express many attributes (e.g., viviparity, genetic and phenotypic variation, ecological adaptation, varied sexual developmental mechanisms, ability to produce fertile interspecies hybrids) that have made attractive research models for over 85 years. Use of various interspecies hybrids to investigate the genetics underlying spontaneous and induced tumorigenesis has resulted in the development and maintenance of pedigreed Xiphophorus lines specifically bred for research. The recent availability of the X. maculatus reference genome assembly now provides unprecedented opportunities for novel and exciting comparative research studies among Xiphophorus species. RESULTS We present sequencing, assembly and annotation of two new genomes representing Xiphophorus couchianus and Xiphophorus hellerii. The final X. couchianus and X. hellerii assemblies have total sizes of 708 Mb and 734 Mb and correspond to 98 % and 102 % of the X. maculatus Jp 163 A genome size, respectively. The rates of single nucleotide change range from 1 per 52 bp to 1 per 69 bp among the three genomes and the impact of putatively damaging variants are presented. In addition, a survey of transposable elements allowed us to deduce an ancestral TE landscape, uncovered potential active TEs and document a recent burst of TEs during evolution of this genus. CONCLUSIONS Two new Xiphophorus genomes and their corresponding transcriptomes were efficiently assembled, the former using a novel guided assembly approach. Three assembled genome sequences within this single vertebrate order of new world live-bearing fishes will accelerate our understanding of relationship between environmental adaptation and genome evolution. In addition, these genome resources provide capability to determine allele specific gene regulation among interspecies hybrids produced by crossing any of the three species that are known to produce progeny predisposed to tumor development.
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Affiliation(s)
- Yingjia Shen
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA.
- Key Laboratory of Coastal and Wetland Ecosystems, Ministry of Education, A316 Environment and Ecology Bldg., Xiamen, Fujian, 361102, China.
| | - Domitille Chalopin
- Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242, Centre National de la Recherche Scientifique, Université de Lyon I, Ecole Normale Supérieure de Lyon, Lyon, France.
| | - Tzintzuni Garcia
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA.
| | - Mikki Boswell
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA.
| | - William Boswell
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA.
| | - Sergey A Shiryev
- The National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, 20894, USA.
| | - Richa Agarwala
- The National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, 20894, USA.
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, Unité Mixte de Recherche 5242, Centre National de la Recherche Scientifique, Université de Lyon I, Ecole Normale Supérieure de Lyon, Lyon, France.
| | - John H Postlethwait
- Institute of Neuroscience, University of Oregon, 1425 E. 13th Avenue, Eugene, OR, 97403, USA.
| | - Manfred Schartl
- Universität Würzburg, Physiologische Chemie I, Biozentrum, Am Hubland, and Comprehensive Cancer Center Mainfranken, University Clinic Würzburg, D-97074, Würzburg, Germany.
| | - Patrick Minx
- Genome Sequencing Center, Washington University School of Medicine, 4444 Forest Park Blvd., St Louis, MO, 63108, USA.
| | - Wesley C Warren
- Genome Sequencing Center, Washington University School of Medicine, 4444 Forest Park Blvd., St Louis, MO, 63108, USA.
| | - Ronald B Walter
- The Xiphophorus Genetic Stock Center, Department of Chemistry and Biochemistry, Texas State University, 419 Centennial Hall, 601 University Drive, San Marcos, TX, 78666, USA.
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Mitchell DL, Fernandez AA, Garcia R, Paniker L, Lin K, Hanninen A, Zigelsky K, May M, Nuttall M, Lo HH, Person MD, Earley R. Acute exposure to ultraviolet-B radiation modulates sex steroid hormones and receptor expression in the skin and may contribute to the sex bias of melanoma in a fish model. Pigment Cell Melanoma Res 2014; 27:408-17. [PMID: 24406016 DOI: 10.1111/pcmr.12213] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 12/06/2013] [Accepted: 01/07/2014] [Indexed: 12/11/2022]
Abstract
Using the Xiphophorus fish melanoma model, we show a strong male bias for sunlight-induced malignant melanoma, consistent with that seen in the human population. To examine underlying factors, we exposed adult X. couchianus fish to a single, sublethal dose of UVB and measured circulating sex steroid hormones and expression of associated hormone receptor genes over a 24-h period. We found that a single exposure had profound effects on circulating levels of steroid hormones with significant decreases for all free sex steroids at 6 and 24 h and increases in conjugated 2-estradiol and 11-ketotestosterone at 6 and 24 h, respectively. Whereas ARα expression increased in male and female skin, neither ARβ nor either of the ERs showed significant responses to UVB in either sex. The rapid response of male androgens and their receptors in the skin after UVB irradiation implicates hormones in the male bias of skin cancer and suggests that the photoendocrine response immediately after UV exposure may be relevant to melanomagenesis.
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Affiliation(s)
- David L Mitchell
- Department of Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX, USA; Graduate School of Biomedical Sciences, The University of Texas, Houston, TX, USA
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Shen Y, Catchen J, Garcia T, Amores A, Beldroth I, Wagner JR, Zhang Z, Postlethwait J, Warren W, Schartl M, Walter RB. Identification of transcriptome SNPs between Xiphophorus lines and species for assessing allele specific gene expression within F₁ interspecies hybrids. Comp Biochem Physiol C Toxicol Pharmacol 2012; 155:102-8. [PMID: 21466860 PMCID: PMC3178741 DOI: 10.1016/j.cbpc.2011.03.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 03/28/2011] [Accepted: 03/28/2011] [Indexed: 12/25/2022]
Abstract
Variations in gene expression are essential for the evolution of novel phenotypes and for speciation. Studying allelic specific gene expression (ASGE) within interspecies hybrids provides a unique opportunity to reveal underlying mechanisms of genetic variation. Using Xiphophorus interspecies hybrid fishes and high-throughput next generation sequencing technology, we were able to assess variations between two closely related vertebrate species, Xiphophorus maculatus and Xiphophorus couchianus, and their F(1) interspecies hybrids. We constructed transcriptome-wide SNP polymorphism sets between two highly inbred X. maculatus lines (JP 163 A and B), and between X. maculatus and a second species, X. couchianus. The X. maculatus JP 163 A and B parental lines have been separated in the laboratory for ≈70 years and we were able to identify SNPs at a resolution of 1 SNP per 49 kb of transcriptome. In contrast, SNP polymorphisms between X. couchianus and X. maculatus species, which diverged ≈5-10 million years ago, were identified about every 700 bp. Using 6524 transcripts with identified SNPs between the two parental species (X. maculatus and X. couchianus), we mapped RNA-seq reads to determine ASGE within F(1) interspecies hybrids. We developed an in silico X. couchianus transcriptome by replacing 90,788 SNP bases for X. maculatus transcriptome with the consensus X. couchianus SNP bases and provide evidence that this procedure overcomes read mapping biases. Employment of the in silico reference transcriptome and tolerating 5 mismatches during read mapping allow direct assessment of ASGE in the F(1) interspecies hybrids. Overall, these results show that Xiphophorus is a tractable vertebrate experimental model to investigate how genetic variations that occur during speciation may affect gene interactions and the regulation of gene expression.
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Affiliation(s)
- Yingjia Shen
- Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
| | - Julian Catchen
- Institute of Neuroscience, University of Oregon, 1425 E. 13th Avenue, Eugene, OR 97403 USA
| | - Tzintzuni Garcia
- Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
| | - Angel Amores
- Institute of Neuroscience, University of Oregon, 1425 E. 13th Avenue, Eugene, OR 97403 USA
| | - Ion Beldroth
- Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
| | - Jonathon R Wagner
- Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
| | - Ziping Zhang
- Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
| | - John Postlethwait
- Institute of Neuroscience, University of Oregon, 1425 E. 13th Avenue, Eugene, OR 97403 USA
| | - Wes Warren
- Genome Sequencing Center, Washington University School of Medicine, 4444 Forest Park Blvd., St Louis, MO 63108, USA
| | - Manfred Schartl
- Physiological Chemistry I, University of Würzburg, Biozentrum, Am Hubland, 97074 Würzburg, Germany
| | - Ronald B. Walter
- Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
- Corresponding author. , PHONE: (512) 245-0357, FAX: (512) 245-2374, Address: Department of Chemistry & Biochemistry, 419 CEN, Texas State University, 601 University Drive, San Marcos, TX, 78666
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Garcia T, Shen Y, Catchen J, Amores A, Schartl M, Postlethwait J, Walter RB. Effects of short read quality and quantity on a de novo vertebrate transcriptome assembly. Comp Biochem Physiol C Toxicol Pharmacol 2012; 155:95-101. [PMID: 21651990 PMCID: PMC3223268 DOI: 10.1016/j.cbpc.2011.05.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 05/20/2011] [Accepted: 05/24/2011] [Indexed: 12/01/2022]
Abstract
For many researchers, next generation sequencing data holds the key to answering a category of questions previously unassailable. One of the important and challenging steps in achieving these goals is accurately assembling the massive quantity of short sequencing reads into full nucleic acid sequences. For research groups working with non-model or wild systems, short read assembly can pose a significant challenge due to the lack of pre-existing EST or genome reference libraries. While many publications describe the overall process of sequencing and assembly, few address the topic of how many and what types of reads are best for assembly. The goal of this project was use real world data to explore the effects of read quantity and short read quality scores on the resulting de novo assemblies. Using several samples of short reads of various sizes and qualities we produced many assemblies in an automated manner. We observe how the properties of read length, read quality, and read quantity affect the resulting assemblies and provide some general recommendations based on our real-world data set.
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Affiliation(s)
- T.I. Garcia
- Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
| | - Y. Shen
- Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
| | - J. Catchen
- Institute of Neuroscience, University of Oregon, 1425 E. 13 Avenue, Eugene, OR 97403, USA
| | - A. Amores
- Institute of Neuroscience, University of Oregon, 1425 E. 13 Avenue, Eugene, OR 97403, USA
| | - M. Schartl
- Universität Würzburg, Physiologische Chemie I, Biozentrum, Am Hubland, D-97074 Würzburg, Germany
| | - J. Postlethwait
- Institute of Neuroscience, University of Oregon, 1425 E. 13 Avenue, Eugene, OR 97403, USA
| | - R. B. Walter
- Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
- Corresponding Author: Ronald B. Walter, Department of Chemistry and Biochemistry, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA, Phone: (512) 245-0358; Fax: (512) 245-1922,
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Yang H, Savage MG, Hazlewood L, Walter RB, Tiersch TR. Offspring production with cryopreserved sperm from a live-bearing fish Xiphophorus maculatus and implications for female fecundity. Comp Biochem Physiol C Toxicol Pharmacol 2012; 155:55-63. [PMID: 21616165 PMCID: PMC3189285 DOI: 10.1016/j.cbpc.2011.04.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 04/28/2011] [Accepted: 04/28/2011] [Indexed: 11/16/2022]
Abstract
Xiphophorus fishes are well-established models for biomedical research of spontaneous or induced tumors, and their use in research dates back to the 1930s. Currently, 58 well-pedigreed lines exist among 24 Xiphophorus species housed as live animals at the Xiphophorus Genetic Stock Center. The technique of sperm cryopreservation has been applied to preserve these valuable genetic resources, and production of offspring has been reported with cryopreserved sperm in two species (X. helleri and X. couchianus). The goal of this research was to establish protocols for sperm cryopreservation and artificial insemination that yield live young in X. maculatus, a widely used research species. The objectives were to: 1) collect basic biological characteristics of males, and quantify the sperm production yield after crushing of dissected testis; 2) cryopreserve sperm from X. maculatus by adapting as necessary the protocols for sperm cryopreservation of X. helleri and X. couchianus; 3) use cryopreserved sperm to inseminate virgin females of X maculatus and other species (X. helleri and X. couchianus), and 4) compare experimental trials over a 3-year period to identify opportunities for improving female fecundity. In total, 117 males were used in this study with a standard length of 2.5 ± 0.3 cm (mean ± SD), body weight of 0.474 ± 0.149 g, and dissected testis weight of 7.1 ± 3.7 mg. Calculation of sperm availability showed 5.9 ± 2.8 × 10(6) sperm cells per mg of testis weight. Offspring were produced from cryopreserved sperm. Male-to-male variation (1-70%) was observed in post-thaw motility despite little variation in motility before freezing (60-90%) or genetic variation (~100 generations of sib-mating). Comparisons of biological factors of males did not have significant correlations with the production of live young, and the influence of females on production of young was identified from the comparison of artificial insemination over 3 years. Overall, this study describes offspring production from cryopreserved sperm in a third species of Xiphophorus fishes, and identifies the opportunities for improving female fecundity which is essential for establishment of germplasm repositories for Xiphophorus fishes.
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Affiliation(s)
- Huiping Yang
- Aquaculture Research Station, Louisiana State University Agricultural Center, 2410 Ben Hur Road, Baton Rouge, Louisiana 70820, USA.
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Downs KP, Shen Y, Pasquali A, Beldorth I, Savage M, Gallier K, Garcia T, Booth RE, Walter RB. Characterization of telomeres and telomerase expression in Xiphophorus. Comp Biochem Physiol C Toxicol Pharmacol 2012; 155:89-94. [PMID: 21619941 PMCID: PMC3208803 DOI: 10.1016/j.cbpc.2011.05.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 05/10/2011] [Accepted: 05/11/2011] [Indexed: 12/15/2022]
Abstract
Research investigating telomere lengths and telomerase expression in vertebrates has progressively become important due to the association of these two biological endpoints with cellular aging and cancer in humans. Studies that rely upon the traditional use of laboratory mice have been faced with limitations largely due to inbred mice possessing large telomeres and ubiquitous expression of telomerase. Recently, a number of small fish species have been shown to provide potentially informative models for examining the role of telomeres and telomerase within intact vertebrate animals. Xiphophorus fishes represent a new world live-bearing genus that has not previously been assessed for telomere length or telomerase expression. To add to the knowledge base of telomere and telomerase biology in vertebrates we assessed telomere length and telomerase expression among several species of Xiphophorus. The telomere lengths in several organs (gill, brain, eyes, testis, ovary and liver) in three species (Xiphophorus hellerii, Xiphophorus maculatus, Xiphophorus couchianus) and also in F(1) interspecies hybrids were approximately 2-6 kb. This size was consistent within the same organs of the same species, as well as between species and F(1) hybrids. Despite possessing relatively short telomere lengths compared to humans, the consistency of size among Xiphophorus species and organs may allow experimental detection of telomere shortening. The relative expression of telomerase reverse transcriptase (TERT) was determined by quantitative real-time PCR. Expression levels of TERT was measured in seven organs (ovary, testis, liver, gill, brain, heart, skin) from X. maculatus, X. hellerii and in control and ultraviolet light (UVB) exposed skin samples from X. maculatus, X. hellerii, and F(1) interspecies hybrids. TERT gene expression was significantly higher in ovary and testis, while all other organs showed low relative TERT expression. Detectable increases in TERT expression were found in skin samples upon UVB exposure. Our findings suggest that Xiphophorus may serve as a suitable model for future studies investigating the association of telomere length and telomerase expression in regard to aging and disease.
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Affiliation(s)
| | | | | | | | | | | | | | - Rachell E. Booth
- Corresponding author. , Phone: (512) 245-2327 ; Fax: (512) 245-2374, Department of Chemistry & Biochemistry, 401 CENT, Texas State University, 601 University Drive, San Marcos, TX, 78666, USA
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Cuevas-Uribe R, Yang H, Daly J, Savage MG, Walter RB, Tiersch TR. Production of F₁ offspring with vitrified sperm from a live-bearing fish, the green swordtail Xiphophorus hellerii. Zebrafish 2011; 8:167-79. [PMID: 21883000 DOI: 10.1089/zeb.2011.0704] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
This study reports the first production of offspring with vitrified sperm from a live-bearing fish Xiphophorus hellerii. The overall goal of this study was to develop streamlined protocols for integration into a standardized approach for vitrification of aquatic species germplasm. The objectives were to (1) estimate acute toxicity of cryoprotectants, (2) evaluate vitrification solutions, (3) compare different thawing methods, (4) evaluate membrane integrity of post-thaw sperm vitrified in different cryoprotectants, and (5) evaluate the fertility of vitrified sperm. Nine cryoprotectants and two commercial vitrification additives were tested for acute toxicity and glass forming ability, alone and in combination. Two vitrification solutions, 40% glycerol (Gly) and 20% Gly+20% ethylene glycol (EG) in 500 mOsmol/kg Hanks' balanced salt solution (HBSS), were selected for vitrification of 10 μL sperm samples using inoculating loops plunged into liquid nitrogen. Samples were thawed at 24°C (one loop in 5 μL of HBSS or three loops in 500 μL of HBSS). Samples thawed in 500 μL were concentrated by centrifugation (1000 g for 5 min at 4°C) into 5 μL for artificial insemination. Offspring were produced from virgin females inseminated with sperm vitrified with 20% Gly+20% EG and concentrated by centrifugation.
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Affiliation(s)
- Rafael Cuevas-Uribe
- Aquaculture Research Station, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
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Smith CC, Ryan MJ. Evolution of sperm quality but not quantity in the internally fertilized fish Xiphophorus nigrensis. J Evol Biol 2010; 23:1759-71. [PMID: 20626545 DOI: 10.1111/j.1420-9101.2010.02041.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Species with alternative reproductive strategies are characterized by discrete differences among males in suites of traits related to competition for fertilizations. Models predict sneaker males should allocate more resources to their ejaculates because they experience sperm competition more frequently and often occupy a disfavoured 'role' owing to subordinance in intramale competition and female preferences for larger males. We examined whether sperm number and quality differed between male strategies in the internally fertilized fish Xiphophorus nigrensis and explored the relationship between sperm morphology and performance. We found sneaker males had similar testes sizes compared to courting males but ejaculates with both more viable and longer lived sperm. Sneaker sperm also had longer midpieces, which was positively correlated with both velocity and longevity. Our study suggests that the evolution of sperm quantity and quality can be decoupled and that the sperm morphology is likely to play an important role in mediating sperm competition through its effects on sperm performance.
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Affiliation(s)
- C C Smith
- University of Texas at Austin, Section of Integrative Biology, Austin, TX 78712, USA.
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Watson CT, Lubieniecki KP, Loew E, Davidson WS, Breden F. Genomic organization of duplicated short wave-sensitive and long wave-sensitive opsin genes in the green swordtail, Xiphophorus helleri. BMC Evol Biol 2010; 10:87. [PMID: 20353595 PMCID: PMC3087554 DOI: 10.1186/1471-2148-10-87] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Accepted: 03/30/2010] [Indexed: 01/10/2023] Open
Abstract
Background Long wave-sensitive (LWS) opsin genes have undergone multiple lineage-specific duplication events throughout the evolution of teleost fishes. LWS repertoire expansions in live-bearing fishes (family Poeciliidae) have equipped multiple species in this family with up to four LWS genes. Given that color vision, especially attraction to orange male coloration, is important to mate choice within poeciliids, LWS opsins have been proposed as candidate genes driving sexual selection in this family. To date the genomic organization of these genes has not been described in the family Poeciliidae, and little is known about the mechanisms regulating the expression of LWS opsins in any teleost. Results Two BAC clones containing the complete genomic repertoire of LWS opsin genes in the green swordtail fish, Xiphophorus helleri, were identified and sequenced. Three of the four LWS loci identified here were linked in a tandem array downstream of two tightly linked short wave-sensitive 2 (SWS2) opsin genes. The fourth LWS opsin gene, containing only a single intron, was not linked to the other three and is the product of a retrotransposition event. Genomic and phylogenetic results demonstrate that the LWS genes described here share a common evolutionary origin with those previously characterized in other poeciliids. Using qualitative RT-PCR and MSP we showed that each of the LWS and SWS2 opsins, as well as three other cone opsin genes and a single rod opsin gene, were expressed in the eyes of adult female and male X. helleri, contributing to six separate classes of adult retinal cone and rod cells with average λmax values of 365 nm, 405 nm, 459 nm, 499 nm, 534 nm and 568 nm. Comparative genomic analysis identified two candidate teleost opsin regulatory regions containing putative CRX binding sites and hormone response elements in upstream sequences of LWS gene regions of seven teleost species, including X. helleri. Conclusions We report the first complete genomic description of LWS and SWS2 genes in poeciliids. These data will serve as a reference for future work seeking to understand the relationship between LWS opsin genomic organization, gene expression, gene family evolution, sexual selection and speciation in this fish family.
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Affiliation(s)
- Corey T Watson
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
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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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Boswell MG, Wells MC, Kirk LM, Ju Z, Zhang Z, Booth RE, Walter RB. Comparison of gene expression responses to hypoxia in viviparous (Xiphophorus) and oviparous (Oryzias) fishes using a medaka microarray. Comp Biochem Physiol C Toxicol Pharmacol 2009; 149:258-65. [PMID: 19049829 DOI: 10.1016/j.cbpc.2008.11.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 11/05/2008] [Accepted: 11/07/2008] [Indexed: 02/02/2023]
Abstract
Gene expression profiling using DNA microarray technology is a useful tool for assessing gene transcript level responses after an organism is exposed to environmental stress. Herein, we detail results from studies using an 8 k medaka (Oryzias latipes) microarray to assess modulated gene expression patterns upon hypoxia exposure of the live-bearing aquaria fish, Xiphophorus maculatus. To assess the reproducibility and reliability of using the medaka array in cross-genus hybridization, a two-factor ANOVA analysis of gene expression was employed. The data show the tissue source of the RNA used for array hybridization contributed more to the observed response of modulated gene targets than did the species source of the RNA. In addition, hierarchical clustering via heat map analyses of groupings of tissues and species (Xiphophorus and medaka) suggests that hypoxia induced similar responses in the same tissues from these two diverse aquatic model organisms. Our Xiphophorus results indicate 206 brain, 37 liver, and 925 gill gene targets exhibit hypoxia induced expression changes. Analysis of the Xiphophorus data to determine those features exhibiting a significant (p<0.05)+/-3 fold change produced only two gene targets within brain tissue and 80 features within gill tissue. Of these 82 characterized features, 39 were identified via homology searching (cut-off E-value of 1 x 10(-5)) and placed into one or more biological process gene ontology groups. Among these 39 genes, metabolic energy changes and manipulation was the most affected biological pathway (13 genes).
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Affiliation(s)
- Mikki G Boswell
- Department of Chemistry and Biochemistry, Molecular Biosciences Research Group, 419 Centennial Hall, Texas State University, 601 University Drive, San Marcos, TX 78666, USA
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Recent papers on zebrafish and other aquarium fish models. Zebrafish 2008; 3:253-61. [PMID: 18248266 DOI: 10.1089/zeb.2006.3.253] [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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