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de Moraes RLR, Sember A, Bertollo LAC, de Oliveira EA, Ráb P, Hatanaka T, Marinho MMF, Liehr T, Al-Rikabi ABH, Feldberg E, Viana PF, Cioffi MDB. Comparative Cytogenetics and Neo-Y Formation in Small-Sized Fish Species of the Genus Pyrrhulina (Characiformes, Lebiasinidae). Front Genet 2019; 10:678. [PMID: 31428127 PMCID: PMC6689988 DOI: 10.3389/fgene.2019.00678] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/27/2019] [Indexed: 12/20/2022] Open
Abstract
Although fishes have traditionally been the subject of comparative evolutionary studies, few reports have concentrated on the application of multipronged modern molecular cytogenetic techniques (such as comparative genomic hybridization = CGH and whole chromosome painting = WCP) to analyze deeper the karyotype evolution of specific groups, especially the historically neglected small-sized ones. Representatives of the family Lebiasinidae (Characiformes) are a notable example, where only a few cytogenetic investigations have been conducted thus far. Here, we aim to elucidate the evolutionary processes behind the karyotype differentiation of Pyrrhulina species on a finer-scale cytogenetic level. To achieve this, we applied C-banding, repetitive DNA mapping, CGH and WCP in Pyrrhulina semifasciata and P. brevis. Our results showed 2n = 42 in both sexes of P. brevis, while the difference in 2n between male and female in P. semifasciata (♂41/♀42) stands out due to the presence of a multiple X1X2Y sex chromosome system, until now undetected in this family. As a remarkable common feature, multiple 18S and 5S rDNA sites are present, with an occasional synteny or tandem-repeat amplification. Male-vs.-female CGH experiments in P. semifasciata highlighted the accumulation of male-enriched repetitive sequences in the pericentromeric region of the Y chromosome. Inter-specific CGH experiments evidenced a divergence between both species’ genomes based on the presence of several species-specific signals, highlighting their inner genomic diversity. WCP with the P. semifasciata-derived Y (PSEMI-Y) probe painted not only the entire metacentric Y chromosome in males but also the X1 and X2 chromosomes in both male and female chromosomes of P. semifasciata. In the cross-species experiments, the PSEMI-Y probe painted four acrocentric chromosomes in both males and females of the other tested Pyrrhulina species. In summary, our results show that both intra- and interchromosomal rearrangements together with the dynamics of repetitive DNA significantly contributed to the karyotype divergence among Pyrrhulina species, possibly promoted by specific populational and ecological traits and accompanied in one species by the origin of neo-sex chromosomes. The present results suggest how particular evolutionary scenarios found in fish species can help to clarify several issues related to genome organization and the karyotype evolution of vertebrates in general.
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Affiliation(s)
- Renata Luiza Rosa de Moraes
- Laboratório de Citogenética de Peixes, Departamento de Genética e Evolução, Universidade Federal de São Carlos (UFSCar), São Carlos, Brazil
| | - Alexandr Sember
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czechia
| | - Luiz Antônio Carlos Bertollo
- Laboratório de Citogenética de Peixes, Departamento de Genética e Evolução, Universidade Federal de São Carlos (UFSCar), São Carlos, Brazil
| | - Ezequiel Aguiar de Oliveira
- Laboratório de Citogenética de Peixes, Departamento de Genética e Evolução, Universidade Federal de São Carlos (UFSCar), São Carlos, Brazil.,Secretaria de Estado de Educação de Mato Grosso - SEDUC-MT, Cuiabá, Brazil
| | - Petr Ráb
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, Liběchov, Czechia
| | - Terumi Hatanaka
- Laboratório de Citogenética de Peixes, Departamento de Genética e Evolução, Universidade Federal de São Carlos (UFSCar), São Carlos, Brazil
| | | | - Thomas Liehr
- Institute of Human Genetics, University Hospital Jena, Jena, Germany
| | | | - Eliana Feldberg
- Laboratório de Genética Animal, Instituto Nacional de Pesquisas da Amazônia, Coordenação de Biodiversidade, Manaus, Brazil
| | - Patrik F Viana
- Laboratório de Genética Animal, Instituto Nacional de Pesquisas da Amazônia, Coordenação de Biodiversidade, Manaus, Brazil
| | - Marcelo de Bello Cioffi
- Laboratório de Citogenética de Peixes, Departamento de Genética e Evolução, Universidade Federal de São Carlos (UFSCar), São Carlos, Brazil.,Institute of Human Genetics, University Hospital Jena, Jena, Germany
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Schmid M, Steinlein C, Feichtinger W, Bogart JP. Chromosome banding in Amphibia. XXXI. The neotropical anuran families Centrolenidae and Allophrynidae. Cytogenet Genome Res 2014; 142:268-85. [PMID: 24776617 DOI: 10.1159/000362216] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2014] [Indexed: 11/19/2022] Open
Abstract
The mitotic chromosomes of 11 species from the anuran families Centrolenidae and Allophrynidae were analyzed by means of conventional staining, banding techniques, and in situ hybridization. The amount, location, and fluorochrome affinities of constitutive heterochromatin, the number and positions of nucleolus organizer regions, and the patterns of telomeric DNA sequences were determined for most of the species. The karyotypes were found to be highly conserved with a low diploid chromosome number of 2n = 20 and morphologically similar chromosomes. The sister group relationship between the Centrolenidae and Allophrynidae (unranked taxon Allocentroleniae) is clearly corroborated by the cytogenetic data. The existence of heteromorphic XY♂/XX♀ sex chromosomes in an initial stage of morphological differentiation was confirmed in Vitreorana antisthenesi. The genome sizes of 4 centrolenid species were determined using flow cytometry. For completeness and for comparative purposes, all previously published cytogenetic data on centrolenids are included.
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Affiliation(s)
- Michael Schmid
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
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Pazian MF, Shimabukuro-Dias CK, Pansonato-Alves JC, Oliveira C, Foresti F. Chromosome painting of Z and W sex chromosomes in Characidium (Characiformes, Crenuchidae). Genetica 2013; 141:1-9. [PMID: 23344657 DOI: 10.1007/s10709-013-9701-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 01/17/2013] [Indexed: 01/23/2023]
Abstract
Some species of the genus Characidium have heteromorphic ZZ/ZW sex chromosomes with a totally heterochromatic W chromosome. Methods for chromosome microdissection associated with chromosome painting have become important tools for cytogenetic studies in Neotropical fish. In Characidium cf. fasciatum, the Z chromosome contains a pericentromeric heterochromatin block, whereas the W chromosome is completely heterochromatic. Therefore, a probe was produced from the W chromosome through microdissection and degenerate oligonucleotide-primed polymerase chain reaction amplification. FISH was performed using the W probe on the chromosomes of specimens of this species. This revealed expressive marks in the pericentromeric region of the Z chromosome as well as a completely painted W chromosome. When applying the same probe on chromosome preparations of C. cf. gomesi and Characidium sp., a pattern similar to C. cf. fasciatum was found, while C. cf. zebra, C. cf. lagosantense and Crenuchus spilurus species showed no hybridization signals. Structural changes in the chromosomes of an ancestral sexual system in the group that includes the species C. cf. gomesi, C. cf. fasciatum and Characidium sp., could have contributed to the process of speciation and could represent a causal mechanism of chromosomal diversification in this group. The heterochromatinization process possibly began in homomorphic and homologous chromosomes of an ancestral form, and this process could have given rise to the current patterns found in the species with sex chromosome heteromorphism.
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Affiliation(s)
- Marlon F Pazian
- Laboratório de Biologia e Genética de Peixes, Departamento de Morfologia, Instituto de Biociências, Universidade Estadual Paulista, Distrito de Rubião Junior S/N, Rubião Júnior, Botucatu, SP, Brazil.
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Phillips R. Evolution of the Sex Chromosomes in Salmonid Fishes. Cytogenet Genome Res 2013; 141:177-85. [DOI: 10.1159/000355149] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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de Bello Cioffi M, Sánchez A, Marchal JA, Kosyakova N, Liehr T, Trifonov V, Bertollo LAC. Whole chromosome painting reveals independent origin of sex chromosomes in closely related forms of a fish species. Genetica 2011; 139:1065-72. [PMID: 21927842 DOI: 10.1007/s10709-011-9610-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 09/08/2011] [Indexed: 11/29/2022]
Abstract
The wolf fish Hoplias malabaricus includes well differentiated sex systems (XY and X(1)X(2)Y in karyomorphs B and D, respectively), a nascent XY pair (karyomorph C) and not recognized sex chromosomes (karyomorph A). We performed the evolutionary analysis of these sex chromosomes, using two X chromosome-specific probes derived by microdissection from the XY and X(1)X(2)Y sex systems. A putative-sex pair in karyomorph A was identified, from which the differentiated XY system was evolved, as well as the clearly evolutionary relationship between the nascent XY system and the origin of the multiple X(1)X(2)Y chromosomes. The lack of recognizable signals on the sex chromosomes after the reciprocal cross-FISH experiments highlighted that they evolved independently from non-homologous autosomal pairs. It is noteworthy that these distinct pathways occur inside the same nominal species, thus exposing the high plasticity of sex chromosome evolution in lower vertebrates. Possible mechanisms underlying this sex determination liability are also discussed.
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Affiliation(s)
- Marcelo de Bello Cioffi
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil.
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Cioffi MB, Sánchez A, Marchal JA, Kosyakova N, Liehr T, Trifonov V, Bertollo LA. Cross-species chromosome painting tracks the independent origin of multiple sex chromosomes in two cofamiliar Erythrinidae fishes. BMC Evol Biol 2011; 11:186. [PMID: 21718509 PMCID: PMC3141436 DOI: 10.1186/1471-2148-11-186] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 06/30/2011] [Indexed: 11/13/2022] Open
Abstract
Background The Erythrinidae fish family is characterized by a large variation with respect to diploid chromosome numbers and sex-determining systems among its species, including two multiple X1X2Y sex systems in Hoplias malabaricus and Erythrinus erythrinus. At first, the occurrence of a same sex chromosome system within a family suggests that the sex chromosomes are correlated and originated from ancestral XY chromosomes that were either homomorphic or at an early stage of differentiation. To identify the origin and evolution of these X1X2Y sex chromosomes, we performed reciprocal cross-species FISH experiments with two sex-chromosome-specific probes designed from microdissected X1 and Y chromosomes of H. malabaricus and E. erythrinus, respectively. Results Our results yield valuable information regarding the origin and evolution of these sex chromosome systems. Our data indicate that these sex chromosomes evolved independently in these two closed related Erythrinidae species. Different autosomes were first converted into a poorly differentiated XY sex pair in each species, and additional chromosomal rearrangements produced both X1X2Y sex systems that are currently present. Conclusions Our data provide new insights into the origin and evolution of sex chromosomes, which increases our knowledge about fish sex chromosome evolution.
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Affiliation(s)
- Marcelo B Cioffi
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil.
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Nagamachi CY, Pieczarka JC, Milhomem SSR, O'Brien PCM, de Souza ACP, Ferguson-Smith MA. Multiple rearrangements in cryptic species of electric knifefish, Gymnotus carapo (Gymnotidae, Gymnotiformes) revealed by chromosome painting. BMC Genet 2010; 11:28. [PMID: 20420709 PMCID: PMC2873553 DOI: 10.1186/1471-2156-11-28] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 04/27/2010] [Indexed: 11/10/2022] Open
Abstract
Background Gymnotus (Gymnotidae, Gymnotiformes) is the Neotropical electric fish genus with the largest geographic distribution and the largest number of species, 33 of which have been validated. The diploid number varies from 2n = 39-40 to 2n = 54. Recently we studied the karyotype of morphologically indistinguishable samples from five populations of G. carapo sensu stricto from the Eastern Amazon of Brazil. We found two cytotypes, 2n = 42 (30 M/SM + 12 ST/A) and 2n = 40 (34 M/SM + 6 ST/A) and we concluded that the differences between the two cryptic species are due to pericentric inversions and one tandem fusion. Results In this study we use for the first time, whole chromosome probes prepared by FACS of the Gymnotus carapo sensu strictu species, cytotype with 2n = 42. Using two color hybridizations we were able to distinguish pairs 1, 2, 3, 7, 9, 14, 16, 18, 19, 20 and 21. It was not possible to separate by FACS and distinguish each of the following chromosome pairs even with dual color FISH: {4,8}; {10,11}; {5,6,17}; {12,13,15}. The FISH probes were then used in chromosome painting experiments on metaphases of the 2n = 40 cytotype. While some chromosomes show conserved synteny, others are rearranged in different chromosomes. Eight syntenic associations were found. Conclusions These results show that the karyotype differences between these cryptic species are greater than assumed by classical cytogenetics. These data reinforce the previous supposition that these two cytotypes are different species, despite the absence of morphological differences. Additionally, the homology of repetitive DNA between the two provides evidence of recent speciation.
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Affiliation(s)
- Cleusa Y Nagamachi
- Laboratório de Citogenética, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil.
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Henning F, Trifonov V, Almeida-Toledo LFD. Use of chromosome microdissection in fish molecular cytogenetics. Genet Mol Biol 2008. [DOI: 10.1590/s1415-47572008000200022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
| | - Vladimir Trifonov
- Siberian Branch of the Russian Academy of Sciences, Russia; University of Cambridge
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Artieri CG, Mitchell LA, Ng SHS, Parisotto SE, Danzmann RG, Hoyheim B, Phillips RB, Morasch M, Koop BF, Davidson WS. Identification of the sex-determining locus of Atlantic salmon (Salmo salar) on chromosome 2. Cytogenet Genome Res 2006; 112:152-9. [PMID: 16276105 DOI: 10.1159/000087528] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Accepted: 04/27/2005] [Indexed: 11/19/2022] Open
Abstract
We have integrated data from linkage mapping, physical mapping and karyotyping to gain a better understanding of the sex-determining locus, SEX, in Atlantic salmon (Salmo salar). SEX has been mapped to Atlantic salmon linkage group 1 (ASL1) and is associated with several microsatellite markers. We have used probes designed from the flanking regions of these sex-linked microsatellite markers to screen a bacterial artificial chromosome (BAC) library, representing an 11.7x coverage of the Atlantic salmon genome, which has been HindIII fingerprinted and assembled into contigs. BACs containing sex-linked microsatellites and their related contigs have been identified and representative BACs have been placed on the Atlantic salmon chromosomes by fluorescent in situ hybridization (FISH). This identified chromosome 2, a large metacentric, as the sex chromosome. By positioning several BACs on this chromosome by FISH, it was possible to orient ASL1 with respect to chromosome 2. The region containing SEX appears to lie on the long arm between marker Ssa202DU and a region of heterochromatin identified by DAPI staining. BAC end-sequencing of clones within sex-linked contigs revealed five hitherto unmapped genes along the sex chromosome. We are using an in silico approach coupled with physical probing of the BAC library to extend the BAC contigs to provide a physical map of ASL1, with a view to sequencing chromosome 2 and, in the process, identifying the sex-determining gene.
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Affiliation(s)
- C G Artieri
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada
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11
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Woram RA, Gharbi K, Sakamoto T, Hoyheim B, Holm LE, Naish K, McGowan C, Ferguson MM, Phillips RB, Stein J, Guyomard R, Cairney M, Taggart JB, Powell R, Davidson W, Danzmann RG. Comparative genome analysis of the primary sex-determining locus in salmonid fishes. Genome Res 2003; 13:272-80. [PMID: 12566405 PMCID: PMC420375 DOI: 10.1101/gr.578503] [Citation(s) in RCA: 190] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We compared the Y-chromosome linkage maps for four salmonid species (Arctic charr, Salvelinus alpinus; Atlantic salmon, Salmo salar; brown trout, Salmo trutta; and rainbow trout, Oncorhynchus mykiss) and a putative Y-linked marker from lake trout (Salvelinus namaycush). These species represent the three major genera within the subfamily Salmoninae of the Salmonidae. The data clearly demonstrate that different Y-chromosomes have evolved in each of the species. Arrangements of markers proximal to the sex-determining locus are preserved on homologous, but different, autosomal linkage groups across the four species studied in detail. This indicates that a small region of DNA has been involved in the rearrangement of the sex-determining region. Placement of the sex-determining region appears telomeric in brown trout, Atlantic salmon, and Arctic charr, whereas an intercalary location for SEX may exist in rainbow trout. Three hypotheses are proposed to account for the relocation: translocation of a small chromosome arm; transposition of the sex-determining gene; or differential activation of a primary sex-determining gene region among the species.
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Affiliation(s)
- Rachael A Woram
- Department of Zoology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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Abstract
Sex chromosomes in fish provide an intriguing view of how sex-determination mechanisms evolve in vertebrates. Many fish species with single-factor sex-determination systems do not have cytogenetically-distinguishable sex chromosomes, suggesting that few sex-specific sequences or chromosomal rearrangements are present and that sex-chromosome evolution is thus at an early stage. We describe experiments examining the linkage arrangement of a Y-chromosomal GH pseudogene (GH-Y) sequence in four species of salmon (chum, Oncorhynchus keta; pink, O. gorbuscha; coho, O. kisutch; chinook, O. tshawytscha). Phylogenetic analysis indicates that GH-Y arose early in Oncorhynchus evolution, after this genus had diverged from Salmo and Salvelinus. However, GH-Y has not been detected in some Oncorhynchus species (O. nerka, O. mykiss and O. clarki), consistent with this locus being deleted in some lineages. GH-Y is tightly linked genetically to the sex-determination locus on the Y chromosome and, in chinook salmon, to another Y-linked DNA marker OtY1. GH-Y is derived from an ancestral GH2 gene, but this latter functional GH locus is autosomal or pseudoautosomal. YY chinook salmon are viable and fertile, indicating the Y chromosome is not deficient of vital genetic functions present on the X chromosome, consistent with sex chromosomes that are in an early stage of divergence.
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Affiliation(s)
- R H Devlin
- Fisheries and Oceans Canada, West Vancouver, BC, Canada.
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Zhang Q, Nakayama I, Fujiwara A, Kobayashi T, Masaoka T, Kitamura S, Devlin RH. Sex identification by male-specific growth hormone pseudogene (GH-psi) in Oncorhynchus masou complex and a related hybrid. Genetica 2002; 111:111-8. [PMID: 11841159 DOI: 10.1023/a:1013799229012] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
It is often difficult to identify sexes of many fish species by conventional cytological method because of the lack of heteromorphic sex chromosomes. Isolation of sex-specific molecular markers is thus important for sexing and for understanding sex chromosome evolution in these species. We have identified genetic sexes by PCR-based male-specificity of a growth hormone pseudogene (GH-psi) in masu and Biwa salmon, two subspecies of the Oncorhynchus masou complex, and their hybrid Honmasu. PCRs with primers designed from sequences of chinook salmon GH genes amplified GH-I and GH-II fragments in both sexes, but a third GH-psi fragment was detected in predominant proportion of males and very few phenotypic females. The consistency of phenotypic sex with genetic sex identified by GH-psi for masu salmon, Biwa salmon and Honmasu was 93.1, 96.7 and 94%, respectively. The remaining individuals showed inconsistency or deviation from sex-specificity: a few phenotypic males lacked the GH-psi, whereas a few phenotypic females possessed the GH-psi. Sequence of the putative GH-psi fragment from such females was identical to that from genetic males, and shared about 95% homology with the corresponding GH-psi fragment from chinook salmon. This result confirmed that these females were really GH-psi-bearing individuals. PCR analyses with primers designed from masu salmon GH-psi gave identical results, indicating that the absence of GH-psi in a few males was not resulted from primer mismatching. These GH-psi-bearing females and GH-psi-absent males were more likely to originate from spontaneous sex reversion than from crossing-over between GH-psi and the sex determination gene/region.
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Affiliation(s)
- Q Zhang
- National Research Institute of Aquaculture, Inland Station, Tamaki, Mie, Japan.
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Phillip RB, Konkol NR, Reed KM, Stein JD. Chromosome painting supports lack of homology among sex chromosomes in Oncorhynchus, Salmo, and Salvelinus (Salmonidae). Genetica 2002; 111:119-23. [PMID: 11841160 DOI: 10.1023/a:1013743431738] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The sex chromosome pair has been identified previously as the largest submetacentric pair in the genome in several species of the genus Salvelinus (eastern trouts and chars) including S. namaycush (lake trout) and as a large subtelocentric/acrocentric pair in several species of the genus Oncorhynchus (Pacific trouts and salmon). Sex chromosomes have not been identified in Salmo (Atlantic salmon and brown trout). Two paint probes, one specific for the short arm (Yp) and the other for the long arm (Yq) of the sex chromosome pair in Salvelinus namaycush were hybridized to chromosomes of Oncorhynchus mykiss (rainbow trout) and O. tshawytscha (chinook salmon) and Salmo salar (Atlantic salmon) and S. trutta (brown trout). The two probes hybridized to two different autosomal pairs in each of the Oncorhynchus species, supporting lack of homology between the sex chromosomes in the two genera. The Yp probe hybridized to interstitial regions on two different chromosome pairs in S. salar and one pair in S. trutta. The Yq probe hybridized to a different pair in both species.
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Affiliation(s)
- R B Phillip
- Department of Biological Sciences, University of Wisconsin-Milwaukee, 53201, USA.
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Baroiller JF, Guiguen Y. Endocrine and environmental aspects of sex differentiation in gonochoristic fish. EXS 2001:177-201. [PMID: 11301598 DOI: 10.1007/978-3-0348-7781-7_9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
This paper reviews current knowledge concerning the endocrine and environmental regulation of gonadal sex differentiation in gonochoristic fish. In gonochoristic fish, although potentially active around this period, the hypothalamo-pituitary axis is probably not involved in triggering sex differentiation. Although steroids and steroidogenic enzymes are probably not the initial triggers of sex differentiation, new data, including molecular approaches, have confirmed that they are key physiological steps in the regulation of this process. Environmental factors can strongly influence sex differentiation in gonochoristic fish. The most important environmental determinant of sex would appear to be temperature. Interactions between environmental factors and genotype have been suggested for gonochoristic fish.
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Affiliation(s)
- J F Baroiller
- CIRAD-EMVT (Centre International en Recherche Agronomique pour le Développement), Campus de Beaulieu, 35042 Rennes, France
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Reed KM, Phillips RB. Polymorphism of the nucleolus organizer region (NOR) on the putative sex chromosomes of Arctic char (Salvelinus alpinus) is not sex related. Chromosome Res 1997; 5:221-7. [PMID: 9244448 DOI: 10.1023/a:1018411417816] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Polymorphism of the nucleolus organizer region (NOR) on the putative sex chromosomes of Arctic char (Salvelinus alpinus) was examined using conventional cytogenetic and molecular techniques. Variation was observed in the number, size and position of rDNA loci on the sex pair. Fluorescence in situ hybridization (FISH) analyses showed that the sex chromosomes of Arctic char lack the repetitive DNA sequences (Mbol/BglII family) that are a prominent feature of the sex chromosomes of lake trout (S. namaycush). Southern analyses of genomic DNAs using an rDNA fragment as probe revealed extensive restriction fragment length polymorphism (RFLP) variation among individuals. Despite the presence of variation in all aspects of this rDNA locus, no sex-specific differences were detected. Repetitive DNAs (multicopy rDNA as in Arctic char or tandem repetitive DNA as in lake trout) appear to play important but different roles in the evolution of the sex chromosomes in these species.
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Affiliation(s)
- K M Reed
- Department of Biological Sciences, University of Wisconsin-Milwaukee 53201, USA.
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