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Langdon QK, Groh JS, Aguillon SM, Powell DL, Gunn T, Payne C, Baczenas JJ, Donny A, Dodge TO, Du K, Schartl M, Ríos-Cárdenas O, Gutierrez-Rodríguez C, Morris M, Schumer M. Genome evolution is surprisingly predictable after initial hybridization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.21.572897. [PMID: 38187753 PMCID: PMC10769416 DOI: 10.1101/2023.12.21.572897] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Over the past two decades, evolutionary biologists have come to appreciate that hybridization, or genetic exchange between distinct lineages, is remarkably common - not just in particular lineages but in taxonomic groups across the tree of life. As a result, the genomes of many modern species harbor regions inherited from related species. This observation has raised fundamental questions about the degree to which the genomic outcomes of hybridization are repeatable and the degree to which natural selection drives such repeatability. However, a lack of appropriate systems to answer these questions has limited empirical progress in this area. Here, we leverage independently formed hybrid populations between the swordtail fish Xiphophorus birchmanni and X. cortezi to address this fundamental question. We find that local ancestry in one hybrid population is remarkably predictive of local ancestry in another, demographically independent hybrid population. Applying newly developed methods, we can attribute much of this repeatability to strong selection in the earliest generations after initial hybridization. We complement these analyses with time-series data that demonstrates that ancestry at regions under selection has remained stable over the past ~40 generations of evolution. Finally, we compare our results to the well-studied X. birchmanni×X. malinche hybrid populations and conclude that deeper evolutionary divergence has resulted in stronger selection and higher repeatability in patterns of local ancestry in hybrids between X. birchmanni and X. cortezi.
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Affiliation(s)
- Quinn K. Langdon
- Department of Biology, Stanford University
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
- Gladstone Institute of Virology, Gladstone Institutes, San Francisco, California
| | - Jeffrey S. Groh
- Center for Population Biology and Department of Evolution and Ecology, University of California, Davis
| | - Stepfanie M. Aguillon
- Department of Biology, Stanford University
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles
| | - Daniel L. Powell
- Department of Biology, Stanford University
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
| | - Theresa Gunn
- Department of Biology, Stanford University
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
| | - Cheyenne Payne
- Department of Biology, Stanford University
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
| | | | - Alex Donny
- Department of Biology, Stanford University
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
| | - Tristram O. Dodge
- Department of Biology, Stanford University
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
| | - Kang Du
- Xiphophorus Genetic Stock Center, Texas State University San Marcos
| | - Manfred Schartl
- Xiphophorus Genetic Stock Center, Texas State University San Marcos
- Developmental Biochemistry, Biocenter, University of Würzburg
| | | | | | | | - Molly Schumer
- Department of Biology, Stanford University
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”, A.C
- Freeman Hrabowski Fellow, Howard Hughes Medical Institute
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2
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Wyngaard GA, Skern-Mauritzen R, Malde K, Prendergast R, Peruzzi S. The salmon louse genome may be much larger than sequencing suggests. Sci Rep 2022; 12:6616. [PMID: 35459797 PMCID: PMC9033869 DOI: 10.1038/s41598-022-10585-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 04/08/2022] [Indexed: 12/30/2022] Open
Abstract
The genome size of organisms impacts their evolution and biology and is often assumed to be characteristic of a species. Here we present the first published estimates of genome size of the ecologically and economically important ectoparasite, Lepeophtheirus salmonis (Copepoda, Caligidae). Four independent L. salmonis genome assemblies of the North Atlantic subspecies Lepeophtheirus salmonis salmonis, including two chromosome level assemblies, yield assemblies ranging from 665 to 790 Mbps. These genome assemblies are congruent in their findings, and appear very complete with Benchmarking Universal Single-Copy Orthologs analyses finding > 92% of expected genes and transcriptome datasets routinely mapping > 90% of reads. However, two cytometric techniques, flow cytometry and Feulgen image analysis densitometry, yield measurements of 1.3-1.6 Gb in the haploid genome. Interestingly, earlier cytometric measurements reported genome sizes of 939 and 567 Mbps in L. salmonis salmonis samples from Bay of Fundy and Norway, respectively. Available data thus suggest that the genome sizes of salmon lice are variable. Current understanding of eukaryotic genome dynamics suggests that the most likely explanation for such variability involves repetitive DNA, which for L. salmonis makes up ≈ 60% of the genome assemblies.
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Affiliation(s)
- Grace A Wyngaard
- Department of Biology, James Madison University, Harrisonburg, VA, USA
| | | | - Ketil Malde
- Institute of Marine Research, Bergen, Norway
- Department of Informatics, University of Bergen, Bergen, Norway
| | | | - Stefano Peruzzi
- Department of Arctic Marine Biology, UiT-the Arctic University of Norway, Tromsø, Norway.
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3
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Hubálek M, Flajšhans M. Simple Field Storage of Fish Samples for Measurement of DNA Content by Flow Cytometry. Cytometry A 2021; 99:743-752. [PMID: 33215865 PMCID: PMC8359303 DOI: 10.1002/cyto.a.24271] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 10/28/2020] [Accepted: 11/16/2020] [Indexed: 11/14/2022]
Abstract
Flow cytometry is an effective and widely used tool for determination of ploidy in fish, but it is not always possible to access the fresh samples for analysis. We investigated the potential for extended storage of fish tissue with sterlet and tench as representative species of Chondrostei and Teleostei, using blood and fin of subadult/adult specimens and tail of larvae. Thirteen procedures for extending storage, selected for rapidity and simplicity in both field and laboratory conditions, were tested for each tissue sample. Flow cytometry was applied to fresh tissue immediately after sampling and to tissue subjected to experimental protocols, always along with species-specific standard, after 1, 5, and 10 days storage at 0-4°C or freezing at -80°C. The fluorochrome 4',6-diamidine-2'-phenylindole dihydrochloride was used with excitation/emission maximum 358/461 nm. Based on the measurability of stored samples, evaluation of directly measured coefficients of variation of their DNA peaks and the changes in fluorescence intensity compared to fresh tissue, optimal procedures for extended storage of the selected tissue types of the model species are suggested. © 2020 The Authors. Cytometry Part A published by Wiley Periodicals LLC. on behalf of International Society for Advancement of Cytometry.
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Affiliation(s)
- Martin Hubálek
- University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of HydrocenosesZátiší 728/II, 389 25VodňanyCzech Republic
| | - Martin Flajšhans
- University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of HydrocenosesZátiší 728/II, 389 25VodňanyCzech Republic
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4
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Park IS. The Nuclear DNA Content Determination of 31 Endemic Freshwater Fishes in Korea. Dev Reprod 2021; 25:25-32. [PMID: 33977172 PMCID: PMC8087261 DOI: 10.12717/dr.2021.25.1.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 02/26/2021] [Accepted: 03/02/2021] [Indexed: 11/17/2022]
Abstract
The main purpose of the current study was to obtain nuclear DNA content data
among the representatives of the families and subfamilies of 31 endemic fishes
that inhabit river of Korea. DNA contents of 31 endemic species were observed to
rang from 1.5 to 4.8 pg DNA/nucleus. In Cyprinidae, DNA content of
Abbottina springeri (1.5±0.03 pg DNA/nucleus) was
the lowest value and DNA content of Carassius cuvieri
(4.5±0.32 pg DNA/nucleus) was the highest value in all experimental
groups. In Cobitidae, DNA content of Iksookimia longicorpa
(3.9±0.17 pg DNA/nucleus) was the highest value and DNA content of
Orthrias toni (1.5±0.18 pg DNA/nucleus) was the
lowest value in all experimental groups. This study provides new information for
a better understanding of the process of genomic evolution in 31 endemic species
in river of Korea.
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Affiliation(s)
- In-Seok Park
- Division of Convergence on Marine Science, College of Ocean Science and Engineering, Korea Maritime & Ocean University, Busan 49112, Korea
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5
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Colléter J, Penman DJ, Lallement S, Fauvel C, Hanebrekke T, Osvik RD, Eilertsen HC, D’Cotta H, Chatain B, Peruzzi S. Genetic inactivation of European sea bass (Dicentrarchus labrax L.) eggs using UV-irradiation: observations and perspectives. PLoS One 2014; 9:e109572. [PMID: 25329931 PMCID: PMC4203730 DOI: 10.1371/journal.pone.0109572] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 09/01/2014] [Indexed: 11/23/2022] Open
Abstract
Androgenesis is a form of uniparental reproduction leading to progenies inheriting only the paternal set of chromosomes. It has been achieved with variable success in a number of freshwater species and can be attained by artificial fertilization of genetically inactivated eggs following exposure to gamma (γ), X-ray or UV irradiation (haploid androgenesis) and by restoration of diploidy by suppression of mitosis using a pressure or thermal shock. The conditions for the genetic inactivation of the maternal genome in the European sea bass (Dicentrarchus labrax L.) were explored using different combinations of UV irradiation levels and durations. UV treatments significantly affected embryo survival and generated a wide range of developmental abnormalities. Despite the wide range of UV doses tested (from 7.2 to 720 mJ x cm(-2)), only one dose (60 mJ x cm(-2) x min(-1) with 1 min irradiation) resulted in a small percentage (14%) of haploid larvae at hatching in the initial trials as verified by flow cytometry. Microsatellite marker analyses of three further batches of larvae produced by using this UV treatment showed a majority of larvae with variable levels of paternal and maternal contributions and only one larva displaying pure paternal inheritance. The results are discussed also in the context of an assessment of the UV-absorbance characteristics of egg extracts in this species that revealed the presence of gadusol, a compound structurally related to mycosporine-like amino acids (MAAs) with known UV-screening properties.
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Affiliation(s)
- Julie Colléter
- Cirad, Persyst, UMR Intrepid, Campus International de Baillarguet, Montpellier, France
- Ifremer, Laboratoire de Recherche Piscicole en Méditerranée, Station Expérimentale d’Aquaculture, Palavas Les Flots, France
| | - David J. Penman
- University of Stirling, Institute of Aquaculture, Stirling, Scotland
| | - Stéphane Lallement
- Ifremer, Laboratoire de Recherche Piscicole en Méditerranée, Station Expérimentale d’Aquaculture, Palavas Les Flots, France
| | - Christian Fauvel
- Ifremer, Laboratoire de Recherche Piscicole en Méditerranée, Station Expérimentale d’Aquaculture, Palavas Les Flots, France
| | - Tanja Hanebrekke
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, University of Tromsø, Tromsø, Norway
| | - Renate D. Osvik
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, University of Tromsø, Tromsø, Norway
| | - Hans C. Eilertsen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, University of Tromsø, Tromsø, Norway
| | - Helena D’Cotta
- Cirad, Persyst, UMR Intrepid, Campus International de Baillarguet, Montpellier, France
| | - Béatrice Chatain
- Ifremer, Laboratoire de Recherche Piscicole en Méditerranée, Station Expérimentale d’Aquaculture, Palavas Les Flots, France
| | - Stefano Peruzzi
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, University of Tromsø, Tromsø, Norway
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Rorat A, Kachamakova-Trojanowska N, Jozkowicz A, Kruk J, Cocquerelle C, Vandenbulcke F, Santocki M, Plytycz B. Coelomocyte-derived fluorescence and DNA markers of composting earthworm species. ACTA ACUST UNITED AC 2013; 321:28-40. [DOI: 10.1002/jez.1834] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 07/16/2013] [Accepted: 09/04/2013] [Indexed: 11/06/2022]
Affiliation(s)
- Agnieszka Rorat
- Institute of Environmental Engineering; Czestochowa University of Technology; Czestochowa Poland
- Laboratoire de Génie Civil et Géo-Environnement; University Lille Nord de France; Lille France
| | | | - Alicja Jozkowicz
- Faculty of Biochemistry; Biophysics and Biotechnology; Jagiellonian University; Cracow Poland
| | - Jerzy Kruk
- Institute of Zoology; Jagiellonian University; Cracow Poland
| | - Claude Cocquerelle
- Laboratoire de Génie Civil et Géo-Environnement; University Lille Nord de France; Lille France
| | - Franck Vandenbulcke
- Laboratoire de Génie Civil et Géo-Environnement; University Lille Nord de France; Lille France
| | - Michal Santocki
- Institute of Zoology; Jagiellonian University; Cracow Poland
| | - Barbara Plytycz
- Institute of Zoology; Jagiellonian University; Cracow Poland
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7
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Filipiak M, Tylko G, Kilarski W. Flow cytometric determination of genome size in European sunbleak Leucaspius delineatus (Heckel, 1843). FISH PHYSIOLOGY AND BIOCHEMISTRY 2012; 38:355-362. [PMID: 21614549 PMCID: PMC3309147 DOI: 10.1007/s10695-011-9512-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 05/13/2011] [Indexed: 05/30/2023]
Abstract
The aim of this study was to compare DNA content in hepatocyte and erythrocyte nuclei of the European sunbleak, Leucaspius delineatus, in relation to nuclear and cell size by means of flow cytometry and fluorescence microscopy. The DNA standards, chicken and rainbow trout erythrocytes, were prepared in parallel with both cell types, with initial separation of liver cells in pepsin solution followed by cell filtering. Standards and investigated cells were stained with a mixture of propidium iodide, citric acid, and Nonidet P40 in the presence of RNAse, and fluorescence of at least 50,000 nuclei was analyzed by flow cytometry. Average cell size was determined by flow cytometry, using fresh cell suspension in relation to latex beads of known diameter. The size of nuclei was examined on the basis of digital micrographs obtained by fluorescence microscopy after nuclei staining with DAPI. The sunbleak's erythrocyte nuclei contain 2.25 ± 0.06 pg of DNA, whereas the hepatocyte nuclei contain 2.46 ± 0.06 pg of DNA. This difference in DNA content was determined spectroscopically using isolated DNA from the two cell types. The modal diameters of the erythrocytes and hepatocytes were estimated to be 5.1 ± 0.2 and 22.3 ± 5.0 μm, respectively, and the corresponding modal dimensions of their nuclei (measured as surface area) were 15.2 and 21.4 μm(2), respectively. The nucleoplasmic index, as calculated from diameters estimated from surface area of nuclear profiles, was 2.51 for the erythrocytes compared with 0.08 for hepatocytes.
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Affiliation(s)
- Marta Filipiak
- Department of Cytology and Histology, Institute of Zoology, Jagiellonian University, 6 Ingardena, 30-060 Krakow, Poland
| | - Grzegorz Tylko
- Department of Cytology and Histology, Institute of Zoology, Jagiellonian University, 6 Ingardena, 30-060 Krakow, Poland
| | - Wincenty Kilarski
- Department of Cytology and Histology, Institute of Zoology, Jagiellonian University, 6 Ingardena, 30-060 Krakow, Poland
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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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9
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Kazianis S, Nairn RS, Walter RB, Johnston DA, Kumar J, Trono D, Della-Coletta L, Gimenez-Conti I, Rains JD, Williams EL, Pino BM, Mamerow MM, Kochan KJ, Schartl M, Vielkind JR, Volff JN, Woolcock B, Morizot DC. The genetic map of Xiphophorus fishes represented by 24 multipoint linkage groups. Zebrafish 2008; 1:287-304. [PMID: 18248238 DOI: 10.1089/zeb.2004.1.287] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Hybrids between distinct Xiphophorus species have been utilized for over 70 years to study melanoma and other neoplasms that can develop spontaneously in hybrid offspring. Genetic linkage mapping has proven to be important in delineating genomic areas that harbor oncogenes and tumor suppressors. Within this report, two parallel backcrosses have been utilized to generate a genetic linkage map for Xiphophorus fishes. Isozyme/allozyme, RFLP and PCR-based mapping techniques, including AP-PCR/RAPDs and microsatellite loci were utilized. The derived linkage map provides a total of 403 mapped polymorphisms distributed among 24 linkage groups, representative of 24 acro- and telocentric chromosome pairs. Genomic coverage is approximately one marker per 5.8 cM. Detailed genotypic analysis of the utilized hybrids revealed two areas of the genome that show significant segregation distortion. Loci within the linkage group harboring the sex determining locus (LG 24) and an autosomal linkage group (LG 21) show highly significant deviations from Mendelian expectations. This phenomenon is not present in a hybrid cross that utilizes a different backcross hybrid progenitor species. The derived map with sequence-tagged markers provides a framework for physical map generation, large-scale genomic sequencing and will further enable cross-genome comparisons of vertebrate genomes.
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Affiliation(s)
- Steven Kazianis
- Wistar Institute, Program of Molecular and Cellular Oncogenesis, Philadelphia, Pennsylvania 19104, USA.
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10
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Walter RB, Ju Z, Martinez A, Amemiya C, Samollow PB. Genomic resources for Xiphophorus research. Zebrafish 2008; 3:11-22. [PMID: 18248243 DOI: 10.1089/zeb.2006.3.11] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Xiphophorus fishes and interspecies hybrids are used in many areas of contemporary research. Due to their high degree of heterozygosity Xiphophorus interspecies hybrids are extremely valuable models for molecular genetic study of gene regulation in physiology and behavior. Historically, Xiphophorus fish have made a contribution to understanding the genetics underlying tumorigenesis but the role this experimental model system may play in contemporary comparative biology has only just begun to be realized. In spite of many advantages a genome-level Xiphophorus sequencing project has not yet been initiated. In order to set a stage for a genome-level initiative, many Xiphophorus resources have recently been, or are currently being developed. Recent completion of the Xiphophorus gene linkage map, construction of microsatellite marker and EST databases, and the accessibility of BAC library resources hallmark the progress in development of genomic capabilities for Xiphophorus investigations. Herein we review current Xiphophorus genomic resources and to provide the reader with information that will enable them to access these resources available to enhance their investigations.
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Affiliation(s)
- Ronald B Walter
- Molecular Biosciences Research Group, Department of Chemistry and Biochemistry, Texas State University, San Marcos, Texas 78666-4616, USA.
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Thirumala S, Huang C, Dong Q, Tiersch TR, Devireddy RV. A theoretically estimated optimal cooling rate for the cryopreservation of sperm cells from a live-bearing fish, the green swordtail Xiphophorus helleri. Theriogenology 2005; 63:2395-415. [PMID: 15910922 PMCID: PMC5592831 DOI: 10.1016/j.theriogenology.2004.09.051] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2004] [Accepted: 09/01/2004] [Indexed: 11/15/2022]
Abstract
Sperm cryopreservation of live-bearing fishes, such as those of the genus Xiphophorus is only beginning to be studied, although these fishes are valuable models for biomedical research and are commercially raised as ornamental fish for use in aquariums. To explore optimization of techniques for sperm cryopreservation of these fishes, this study measured the volumetric shrinkage response during freezing of sperm cells of Xiphophorus helleri by use of a shape-independent differential scanning calorimeter (DSC) technique. Volumetric shrinkage during freezing of X. helleri sperm cell suspensions was obtained in the presence of extracellular ice at a cooling rate of 20 degrees C/min in three different media: (1) Hanks' balanced salt solution (HBSS) without cryoprotective agents (CPAs); (2) HBSS with 14% (v/v) glycerol; and (3) HBSS with 10% (v/v) dimethyl sulfoxide (DMSO). The sperm cell was modeled as a cylinder of 33.3 microm in length and 0.59 microm in diameter with an osmotically inactive cell volume (V(b)) of 0.6V(o), where V(o) is the isotonic or initial cell volume. By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the best-fit membrane permeability parameters (reference membrane permeability to water, L(pg) or L(pg)[cpa] and the activation energy, E(Lp) or E(Lp)[cpa]) of the Xiphophorus helleri sperm cell membrane were determined. The best-fit membrane permeability parameters at 20 degrees C/min in the absence of CPAs were: L(pg)=0.776 x 10(-15)m3/Ns (0.0046 microm/min atm), and E(Lp)=50.1 kJ/mol (11.97 kcal/mol) (R2=0.997). The corresponding parameters in the presence of 14% glycerol were L(pg)[cpa]=1.063 x 10(-15)m3/Ns (0.0063 microm/min atm), and E(Lp)[cpa]=83.81 kJ/mol (20.04 kcal/mol) (R2=0.997). The parameters in the presence of 10% DMSO were L(pg)[cpa]=1.4 x 10(-15)m3/Ns (0.0083 microm/min atm), and E(Lp)[cpa]=90.96 kJ/mol (21.75 kcal/mol) (R2=0.996). Parameters obtained in this study suggested that the optimal rate of cooling for X. helleri sperm cells in the presence of CPAs ranged from 20 to 35 degrees C/min and were in close agreement with recently published, empirically determined optimal cooling rates.
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Affiliation(s)
- Sreedhar Thirumala
- Bioengineering Laboratory, Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA, USA
| | - Changjiang Huang
- Aquaculture Research Station, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, LA, USA
| | - Qiaoxiang Dong
- Aquaculture Research Station, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, LA, USA
| | - Terrence R. Tiersch
- Aquaculture Research Station, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, LA, USA
| | - Ram V. Devireddy
- Bioengineering Laboratory, Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA, USA
- Corresponding author. Tel.: 1 225 578 5891; fax: +1 225 578 5924. (R.V. Devireddy)
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12
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Walter RB, Rains JD, Russell JE, Guerra TM, Daniels C, Johnston DA, Kumar J, Wheeler A, Kelnar K, Khanolkar VA, Williams EL, Hornecker JL, Hollek L, Mamerow MM, Pedroza A, Kazianis S. A microsatellite genetic linkage map for Xiphophorus. Genetics 2005; 168:363-72. [PMID: 15454549 PMCID: PMC1448116 DOI: 10.1534/genetics.103.019349] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interspecies hybrids between distinct species of the genus Xiphophorus are often used in varied research investigations to identify genomic regions associated with the inheritance of complex traits. There are 24 described Xiphophorus species and a greater number of pedigreed strains; thus, the number of potential interspecies hybrid cross combinations is quite large. Previously, select Xiphophorus experimental crosses have been shown to exhibit differing characteristics between parental species and among the hybrid fishes derived from crossing them, such as widely differing susceptibilities to chemical or physical agents. For instance, genomic regions harboring tumor suppressor and oncogenes have been identified via linkage association of these loci with a small set of established genetic markers. The power of this experimental strategy is related to the number of genetic markers available in the Xiphophorus interspecies cross of interest. Thus, we have undertaken the task of expanding the suite of easily scored markers by characterization of Xiphophorus microsatellite sequences. Using a cross between Xiphophorus maculatus and X. andersi, we report a linkage map predominantly composed of microsatellite markers. All 24 acrocentric chromosome sets of Xiphophorus are represented in the assembled linkage map with an average intergenomic distance of 7.5 cM. Since both male and female F1 hybrids were used to produce backcross progeny, these recombination rates were compared between "male" and "female" maps. Although several genomic regions exhibit differences in map length, male- and female-derived maps are similar. Thus Xiphophorus, in contrast to zebrafish, Danio rerio, and several other vertebrate species, does not show sex-specific differences in recombination. The microsatellite markers we report can be easily adapted to any Xiphophorus interspecies and some intraspecies crosses, and thus provide a means to directly compare results derived from independent experiments.
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Affiliation(s)
- R B Walter
- Molecular Biosciences Research Group, Department of Chemistry and Biochemistry, Texas State University, San Marcos 78666, USA.
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Huang C, Dong Q, Walter RB, Tiersch TR. Initial studies on sperm cryopreservation of a live-bearing fish, the green swordtail Xiphophorus helleri. Theriogenology 2004; 62:179-94. [PMID: 15159112 PMCID: PMC5593138 DOI: 10.1016/j.theriogenology.2003.09.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2003] [Accepted: 09/15/2003] [Indexed: 10/26/2022]
Abstract
Swordtails and platyfish of the genus Xiphophorus are valuable models for biomedical research and are also commercially raised as ornamental fish valued by aquarists. While research use and commercial interest increases yearly in these fish, cryopreservation of sperm is unexplored in this genus. Xiphophorus are live-bearing fishes characterized by small body sizes, limited sperm volumes, and internal fertilization, an atypical reproductive mode for fish. These attributes make research involving cryopreservation of Xiphophorus germplasm challenging. To explore methods for sperm cryopreservation, this study evaluated the effect of different loading volumes of sperm suspension in 0.25-ml French straws, different dilution ratios of sperm to extender, an osmolality range of extender without cryoprotectant and with dimethyl sulfoxide (DMSO) as cryoprotectant, and short-term storage at room temperature and 4 degrees C after thawing. No significant difference in sperm motility due to straw loading volume was observed after thawing. Sperm motility was observed to decrease with increasing dilution. The osmolality of Hanks' balanced salt solution (HBSS) without cryoprotectant in which the highest sperm motility (67%) was observed was 320 +/- 3 mOsm/kg, which was also the osmolality of X. helleri blood plasma. When cryopreserved with 10% DMSO, however, the highest motilities within 10 min after thawing were observed with HBSS in the range of 240-300 mOsm/kg. Sperm suspended in HBSS at 320 mOsm/kg with a dilution factor of 100 maintained motility for 24h at room temperature, but persisted for 10 days when stored at 4 degrees C. These results provided the first evidence that cryopreservation may be applied to conservation of genetic resources in live-bearing fishes.
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Affiliation(s)
- Changjiang Huang
- Aquaculture Research Station, Louisiana State University Agricultural Center, Louisiana Agricultural Experiment Station, Baton Rouge, LA 70803, USA
| | - Qiaoxiang Dong
- Aquaculture Research Station, Louisiana State University Agricultural Center, Louisiana Agricultural Experiment Station, Baton Rouge, LA 70803, USA
| | - Ronald B. Walter
- Department of Chemistry and Biochemistry, Xiphophorus Genetic Stock Center, Texas State University, San Marcos, TX 78666, USA
| | - Terrence R. Tiersch
- Aquaculture Research Station, Louisiana State University Agricultural Center, Louisiana Agricultural Experiment Station, Baton Rouge, LA 70803, USA
- Corresponding author. Tel.: +1-225-765-2848; fax: +1-225-765-2877. (T.R. Tiersch)
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Wilhelm J, Pingoud A, Hahn M. Real-time PCR-based method for the estimation of genome sizes. Nucleic Acids Res 2003; 31:e56. [PMID: 12736322 PMCID: PMC156059 DOI: 10.1093/nar/gng056] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The fast and reliable estimation of the genome sizes of various species would allow for a systematic analysis of many organisms and could reveal insights into evolutionary processes. Many methods for the estimation of genome sizes have already been described. The classical methods are based on the determination of the phosphate content in the DNA backbone of total DNA isolated from a defined number of cells or on reassociation kinetics of high molecular weight genomic DNA (c(0)t assay). More recent techniques employ DNA-specific fluorescent dyes in flow cytometry analysis, image analysis or absorption cytometry after Feulgen staining. The method presented here is based on the absolute quantification of genetic elements in a known amount (mass) of genomic DNA by real-time quantitative PCR. The method was evaluated on three different eukaryotic species, Saccharomyces cerevisiae (12.1 Mb), Xiphophorus maculatus (550 Mb) and Homo sapiens sapiens (2.9 Gb), and found to be fast, highly accurate and reliable.
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Affiliation(s)
- Jochen Wilhelm
- Institut für Biochemie, FB 08, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany
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15
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Jagoe CH, Welter DA. Quantitative comparisons of the morphology and ultrastructure of erythrocyte nuclei from seven freshwater fish species. CAN J ZOOL 1995. [DOI: 10.1139/z95-229] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chromosome number and genomic DNA content vary widely among fish species, and ploidy can vary within species. This suggests that the size, shape, and morphological features of cell nuclei may also vary. Nucleated erythrocytes of fish are an easily sampled homogeneous population of differentiated cells ideal for inter- and intra-species comparisons. We collected blood samples from largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), chain pickerel (Esox niger), yellow perch (Perca flavescens), mosquitofish (Gambusia holbrooki), redeye bass (Micropterus coosae), and rainbow trout (Oncorhynchus mykiss) and removed cytoplasm and nuclear membranes from blood cells. Individual nuclei were examined and measured using scanning electron microscopy and a computerized image analysis system, and inter- and intra-species differences evaluated by nested analysis of variance. Nuclear size and shape varied significantly among species. Isolated nuclei had conspicuous apertures or holes, and the number and size of these holes also varied significantly among species. Variations in nuclear size and structure within species were small compared with interspecies differences. Little is known of the ultrastructure of erythrocyte nuclei in lower vertebrates, but their structure differs considerably from that of other vertebrate non-erythroid cells, suggesting that the organization of their DNA and associated proteins may be different.
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16
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De Vita R, Cavallo D, Eleuteri P, Dell'Omo G. Evaluation of interspecific DNA content variations and sex identification in Falconiformes and Strigiformes by flow cytometric analysis. CYTOMETRY 1994; 16:346-50. [PMID: 7527316 DOI: 10.1002/cyto.990160409] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A high interspecific karyotype variability has been evidenced in birds especially in Falconiformes and Strigiformes. Avian cytogenetic analysis, conventionally used for this study, presents several difficulties. We used flow cytometric analysis in order to obtain further information on the DNA patterns of different species of birds belonging to the above-mentioned orders. Our study was performed on blood samples while chicken erythrocytes and human lymphocytes, with known cytometric DNA content, were used as reference cells. The blood samples of the birds under study were stained, simultaneously to the reference cell, with a lysis-staining buffer containing propidium iodide. The nuclear DNA content of the bird samples was calculated as DNA index in relation to reference cells, and was expressed as nuclear DNA mass in picograms (pg) with respect to the standard value of 7.0 pg per human lymphocyte nucleus. The results obtained showed an interspecific variability of DNA content and evidenced the usefulness of FCM analysis as a rapid and easy tool for studying the DNA pattern of different species of birds. Moreover, our results have confirmed and extended the possibility of sex identification in species of birds characterized by sexual monomorphism by evaluating the small DNA content difference which exists between males and females.
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Affiliation(s)
- R De Vita
- Environmental Biomedicine Division, ENEA Casaccia, Rome, Italy
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17
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Dawley RM. Clonal hybrids of the common laboratory fish Fundulus heteroclitus. Proc Natl Acad Sci U S A 1992; 89:2485-8. [PMID: 1549614 PMCID: PMC48683 DOI: 10.1073/pnas.89.6.2485] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
All-female hybrids of the killifishes Fundulus heteroclitus and Fundulus diaphanus, known from two sites in Nova Scotia, Canada, are shown to reproduce clonally. Isozyme analysis of crosses between female hybrids and male F. heteroclitus reveals that their progeny are genetically identical and show no evidence of recombination or paternal inheritance. Flow cytometric measurement of DNA content shows the hybrids to be diploid, with DNA values intermediate to those of the parental species. Because they are related to F. heteroclitus, a fish used widely as a model organism in experimental biology, the clonal hybrids are potentially valuable for experimental studies requiring subjects with a constant genetic background. In addition, the discovery of unisexuality and cloning in a fish whose reproductive physiology and development are so well characterized provides a unique opportunity to examine the underlying causes of clonal reproduction in vertebrates.
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Affiliation(s)
- R M Dawley
- Department of Biology, Ursinus College, Collegeville, PA 19426
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