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Jeremy B Searle - One of the best experts on this subject based on the ideXlab platform.
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origin of the chromosomal radiation of madeiran house mice a microsatellite analysis of Metacentric Chromosomes
Heredity, 2013Co-Authors: Jeremy B Searle, Daniel W Forster, Maria Da Luz Mathias, Janice BrittondavidianAbstract:Chromosome races of Mus musculus domesticus are characterised by particular sets of Metacentric Chromosomes formed by Robertsonian fusions and whole-arm reciprocal translocations. The Atlantic island of Madeira is inhabited by six chromosome races of house mice with 6–9 pairs of Metacentric Chromosomes. Three of these races are characterised by the Metacentric 3.8 also found elsewhere in the distribution of M. m. domesticus, including Denmark and Spain. We investigated the possibility that Metacentric 3.8 was introduced to Madeira during the initial colonisation, as this could have ‘seeded' the cascade of chromosomal mutation that is the basis of the extraordinary chromosomal radiation observed on the island. Variation at 24 microsatellite loci mapping to three different chromosomal regions (proximal, interstitial and distal) of mouse Chromosomes 3 and 8 was investigated in 179 mice from Madeira, Denmark, Portugal, Spain, Italy and Scotland. Analyses of microsatellite loci closely linked to the centromeres of these Chromosomes (‘proximal loci') do not support a common evolutionary origin of Metacentric 3.8 among Madeiran, Danish and Spanish mouse populations. Our results suggest that Madeiran mice are genetically more similar to standard karyotype mice from Portugal than to Metacentric mice from elsewhere. There is expected to be an interruption to gene flow between hybridising Metacentric races on Madeira, particularly in the chromosomal regions close to the rearrangement breakpoints. Consistent with this, relating to differentiation involving Chromosomes 3 and 8 on Madeira, we found greater genetic structure among races for proximal than interstitial or distal loci.
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Properties of a hybrid zone between highly distinct chromosomal races of the house mouse (Mus musculus domesticus) in Northern Italy, and comparisons with other hybrid zones.
Cytogenetic and genome research, 2011Co-Authors: Heidi C. Hauffe, Thomas A White, Mabel D. Giménez, Rodrigo Vega, Jeremy B SearleAbstract:Here we provide the first detailed description of the hybrid zone between the Cremona chromosomal race of house mouse (ICRE; 2n = 22) and the standard all-telocentric race (40ST; 2n = 40), with full karyotypes of 106 individuals from 17 localities along a transect between the 2 races to the west of Lake Garda in Northern Italy. The ICRE race is characterised by 9 pairs of Metacentric Chromosomes in a homozygous state and we use the Metacentric frequency data along the transect to fit tanh Metacentric clines. The clines are narrow (5-8 km, standardised width) suggesting low hybrid fitness. However, the lack of occurrence of ICRE × 40ST F(1) hybrids and presence of other hybrid types suggests that the F(1) hybrids initially produced in this hybrid zone were at least partially fertile, despite having 9 meiotic trivalent configurations. We apply the same cline-fitting methodology to 3 previously studied hybrid zones between Metacentric races and the 40ST race. Taken together with published clinal data on 4 further Metacentric-40ST hybrid zones, we are able to make objective generalisations on the characteristics of such zones in the house mouse. Zones involving 22-chromosome races are narrower, on average, than other Metacentric-40ST hybrid zones and do not show a tendency towards the generation of new races as found with zones where the Metacentric race has a higher 2n. It appears that Metacentric-40ST zones are unlikely to be sites of speciation (even when a 22-chromosome race is involved), although a mosaic structure to the hybrid zone may enhance this possibility. We make a comparison between Metacentric-40ST zones and contacts between 2 Metacentric races, for a comprehensive perspective of chromosomal hybrid zones in the house mouse.
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natural hybridization between extremely divergent chromosomal races of the common shrew sorex araneus soricidae soricomorpha hybrid zone in siberia
Journal of Evolutionary Biology, 2011Co-Authors: Nina Bulatova, R M Jones, Thomas A White, N A Shchipanov, Svetlana Pavlova, Jeremy B SearleAbstract:Chromosomal races of the common shrew differ in sets of Metacentric Chromosomes and on contact may produce hybrids with extraordinarily complex configurations at meiosis I that are associated with reduced fertility. There is an expectation that these may be some of the most extreme tension zones available for study and therefore are of interest as potential sites for reproductive isolation. Here, we analyse one of these zones, between the Novosibirsk race (characterized by Metacentrics go, hn, ik, jl, mp and qr) and the Tomsk race (Metacentrics gk, hi, jl and mn and acrocentrics o, p, q and r), which form hybrids with a chain-of-nine (CIX) and a chain-of-three (CIII) configuration at meiosis I. At the Novosibirsk-Tomsk hybrid zone, the CIX Chromosomes form clines of 8.53 km standardized width on average, whereas the cline for the CIII Chromosomes was 52.83 km wide. The difference in these cline widths fits with the difference in meiotic errors expected with the CIX and CIII configuration, and we produce estimates of selection against hybrids with these types of configurations, which we relate to dispersal and age of the hybrid zone. The hybrid zone is located at the isocline at 200 m altitude above sea level; this relationship between the races and altitude is suggested at both coarse and fine scales. This indicates adaptive differences between the races that may in turn have been promoted by the chromosome differences. Thus, the extreme chromosomal divergence between the Novosibirsk and Tomsk may be associated with genic differentiation, but it is still striking that, despite the large chromosomal differences, reproductive isolation between the Novosibirsk and Tomsk races has not occurred.
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robertsonian Metacentrics of the house mouse lose telomeric sequences but retain some minor satellite dna in the pericentromeric area
Chromosoma, 1995Co-Authors: Silvia Garagna, Jeremy B Searle, Dominique Broccoli, Carlo Alberto Redi, Howard J Cooke, Ernesto CapannaAbstract:A combination of cytogenetic and molecular biology techniques were used to study the molecular composition and organisation of the pericentromeric regions of house mouse Metacentric Chromosomes, the products of Robertsonian (Rb) translocations between telocentrics. Regardless of whether mitotic or meiotic preparations were used, in situ hybridisation failed to reveal pericentromeric telomeric sequences on any of the Rb Chromosomes, while all Metacentrics retained detectable, although reduced (average 50 kb), amounts of minor satellite DNA in the vicinity of their centromeres. These results were supported by slot blot hybridisation which indicated that mice with 2n=22 Rb Chromosomes have 65% of telomeric sequences (which are allocated to the distal telomeres of both Rb and telocentric Chromosomes and to the proximal telomeres of telocentrics) and 15% the amount of minor satellite, compared with mice with 2n=40 all-telocentric Chromosomes. Pulsed field gel electrophoresis and Southern analysis of DNA from Rb mice showed that the size of the telomeric arrays is similar to that of mice with all-telocentric Chromosomes and that the minor satellite sequences were hybridising to larger fragments incorporating major satellite DNA. Since the telomeric sequences are closer to the physical end of the chromosome than the minor satellite sequences, the absence of telomeric sequences and the reduced amount of minor satellite sequences at the pericentromeric region of the Rb Metacentrics suggest that the breakpoints for the Rb translocation occur very close to the minor satellite-major satellite border. Moreover, it is likely that the minor satellite is required for centromeric function, 50–67 kb being enough DNA to organise one centromere with a functionally active kinetochore.
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Further studies of a staggered hybrid zone in Mus musculus domesticus (the house mouse)
Heredity, 1993Co-Authors: Jeremy B Searle, Yolanda Narain Navarro, Guila GanemAbstract:Abstract In the extreme north-east of Scotland (near the village of John o'Groats) there is a small karyotypic race of house mouse (2n = 32), characterized by four Metacentric Chromosomes 4.10, 9.12, 6.13 and 11.14. We present new data on the hybrid zone between this form and the standard race (2n = 40) and show an association between race and habitat. In a transect south of John o'Groats we demonstrate that the clines for arm combinations 4.10 and 9.12 are staggered relative to the clines for 6.13 and 11.14, confirming previous data collected along an east-west transect (Searle, 1991). There are populations within the John o'Groats-standard hybrid zone dominated by individuals with 36 Chromosomes (homozygous for 4.10 and 9.12), which may represent a novel karyotypic form that has arisen within the zone. Alternatively the type with 36 Chromosomes may have been the progenitor of the John o'Groats race. Additional cytogenetic interest is provided by the occurrence of a homogeneous staining region on one or both copies of chromosome 1 in some mice from the zone.
Roy G Danzmann - One of the best experts on this subject based on the ideXlab platform.
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a snp based linkage map of the arctic charr salvelinus alpinus genome provides insights into the diploidization process after whole genome duplication
G3: Genes Genomes Genetics, 2017Co-Authors: Cameron M Nugent, Moira M Ferguson, Joseph D Norman, Anne A Easton, Roy G DanzmannAbstract:Diploidization, which follows whole genome duplication events, does not occur evenly across the genome. In salmonid fishes, certain pairs of homeologous Chromosomes preserve tetraploid loci in higher frequencies toward the telomeres due to residual tetrasomic inheritance. Research suggests this occurs only in homeologous pairs where one chromosome arm has undergone a fusion event. We present a linkage map for Arctic charr (Salvelinus alpinus), a salmonid species with relatively fewer chromosome fusions. Genotype by sequencing identified 19,418 SNPs, and a linkage map consisting of 4508 markers was constructed from a subset of high quality SNPs and microsatellite markers that were used to anchor the new map to previous versions. Both male- and female-specific linkage maps contained the expected number of 39 linkage groups. The chromosome type associated with each linkage group was determined, and 10 stable Metacentric Chromosomes were identified, along with a chromosome polymorphism involving the sex chromosome AC04. Two instances of a weak form of pseudolinkage were detected in the telomeric regions of homeologous chromosome arms in both female and male linkage maps. Chromosome arm homologies within the Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) genomes were determined. Paralogous sequence variants (PSVs) were identified, and their comparative BLASTn hit locations showed that duplicate markers exist in higher numbers on seven pairs of homeologous arms, previously identified as preserving tetrasomy in salmonid species. Homeologous arm pairs where neither arm has been part of a fusion event in Arctic charr had fewer PSVs, suggesting faster diploidization rates in these regions.
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genome evolution in the fish family salmonidae generation of a brook charr genetic map and comparisons among charrs arctic charr and brook charr with rainbow trout
BMC Genetics, 2011Co-Authors: Evan R Timusk, Moira M Ferguson, Hooman K Moghadam, Joseph D Norman, Chris C Wilson, Roy G DanzmannAbstract:Salmonids are regarded as 4R derivative species, having experienced 4 whole genome duplication events in their ancestry. Many duplicated chromosome regions still share extensive homology with one another which is maintained primarily through male-based homeologous chromosome pairings during meiosis. The formation of quadrivalents during meiosis leads to pseudolinkage. This phenomenon is more prevalent within 5 of the 12 ancestral teleost linkage groups in salmonids. We constructed a genetic linkage map for brook charr and used this in combination with the genetic map from Arctic charr, to make comparisons with the genetic map of rainbow trout. Although not all chromosome arms are currently mapped, some homologous chromosome rearrangements were evident between Arctic charr and brook charr. Notably, 10 chromosome arms in brook charr representing 5 Metacentric Chromosomes in Arctic charr have undergone rearrangements. Three Metacentrics have one arm translocated and fused with another chromosome arm in brook charr to a make a new Metacentrics while two Metacentrics are represented by 4 acrocentric pairs in brook charr. In two cases (i.e., BC-4 and BC-16), an apparent polymorphism was observed with the identification of both a putative Metacentric structure (similar to Metacentric AC-4 = BC-4 and a joining of acrocentric AC-16 + one arm of AC-28 = BC-16), as well as two separate acrocentric linkage groups evident in the mapping parents. Forty-six of the expected 50 karyotypic arms could be inter-generically assigned. SEX in brook charr (BC-4) was localized to the same homologous linkage group region as in Arctic charr (AC-4). The homeologous affinities detected in the two charr species facilitated the identification of 20 (expected number = 25) shared syntenic regions with rainbow trout, although it is likely that some of these regions were partial or overlapping arm regions. Inter-generic comparisons among 2 species of charr (genus Salvelinus) and a trout (genus Oncorhynchus) have identified that linkage group arm arrangements are largely retained among these species. Previous studies have revealed that up to 7 regions of high duplicate marker retention occur between Salmo species (i.e., Atlantic salmon and brown trout) and rainbow trout, with 5 of these regions exhibiting higher levels of pseudolinkage. Pseudolinkage was detected in the charr species (i.e., BC-1/21, AC-12/27, AC-6/23, = RT-2p/29q, RT-12p/16p, and RT-27p/31p, respectively) consistent with three of the five 'salmonid-specific' pseudolinkage regions. Chromosome arms with the highest number of duplicated markers in rainbow trout are the linkage group arms with the highest retention of duplicated markers in both charr species.
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assignment of atlantic salmon salmo salar linkage groups to specific Chromosomes conservation of large syntenic blocks corresponding to whole chromosome arms in rainbow trout oncorhynchus mykiss
BMC Genetics, 2009Co-Authors: Roy G Danzmann, Ruth B. Phillips, Kimberly A. Keatley, Matthew R. Morasch, Abigail B. Ventura, Krzysztof P. Lubieniecki, Ben F. Koop, William S. DavidsonAbstract:Most teleost species, especially freshwater groups such as the Esocidae which are the closest relatives of salmonids, have a karyotype comprising 25 pairs of acrocentric Chromosomes and 48–52 chromosome arms. After the common ancestor of salmonids underwent a whole genome duplication, its karyotype would have 100 chromosome arms, and this is reflected in the modal range of 96–104 seen in extant salmonids (e.g., rainbow trout). The Atlantic salmon is an exception among the salmonids as it has 72–74 chromosome arms and its karyotype includes 12 pairs of large acrocentric Chromosomes, which appear to be the result of tandem fusions. The purpose of this study was to integrate the Atlantic salmon's linkage map and karyotype and to compare the chromosome map with that of rainbow trout. The Atlantic salmon genetic linkage groups were assigned to specific Chromosomes in the European subspecies using fluorescence in situ hybridization with BAC probes containing genetic markers mapped to each linkage group. The genetic linkage groups were larger for Metacentric Chromosomes compared to acrocentric Chromosomes of similar size. Comparison of the Atlantic salmon chromosome map with that of rainbow trout provides strong evidence for conservation of large syntenic blocks in these species, corresponding to entire chromosome arms in the rainbow trout. It had been suggested that some of the large acrocentric Chromosomes in Atlantic salmon are the result of tandem fusions, and that the small blocks of repetitive DNA in the middle of the arms represent the sites of chromosome fusions. The finding that the chromosomal regions on either side of the blocks of repetitive DNA within the larger acrocentric Chromosomes correspond to different rainbow trout chromosome arms provides support for this hypothesis.
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Assignment of Atlantic salmon ( Salmo salar) linkage groups to specific Chromosomes: Conservation of large syntenic blocks corresponding to whole chromosome arms in rainbow trout ( Oncorhynchus mykiss )
BMC Genetics, 2009Co-Authors: Ruth B. Phillips, Roy G Danzmann, Kimberly A. Keatley, Matthew R. Morasch, Abigail B. Ventura, Krzysztof P. Lubieniecki, Ben F. Koop, William S. DavidsonAbstract:Background: Most teleost species, especially freshwater groups such as the Esocidae which are the closest relatives of salmonids, have a karyotype comprising 25 pairs of acrocentric Chromosomes and 48– 52 chromosome arms. After the common ancestor of salmonids underwent a whole genome duplication, its karyotype would have 100 chromosome arms, and this is reflected in the modal range of 96–104 seen in extant salmonids (e.g., rainbow trout). The Atlantic salmon is an exception among the salmonids as it has 72–74 chromosome arms and its karyotype includes 12 pairs of large acrocentric Chromosomes, which appear to be the result of tandem fusions. The purpose of this study was to integrate the Atlantic salmon's linkage map and karyotype and to compare the chromosome map with that of rainbow trout. Results: The Atlantic salmon genetic linkage groups were assigned to specific Chromosomes in the European subspecies using fluorescence in situ hybridization with BAC probes containing genetic markers mapped to each linkage group. The genetic linkage groups were larger for Metacentric Chromosomes compared to acrocentric Chromosomes of similar size. Comparison of the Atlantic salmon chromosome map with that of rainbow trout provides strong evidence for conservation of large syntenic blocks in these species, corresponding to entire chromosome arms in the rainbow trout. Conclusion: It had been suggested that some of the large acrocentric Chromosomes in Atlantic salmon are the result of tandem fusions, and that the small blocks of repetitive DNA in the middle of the arms represent the sites of chromosome fusions. The finding that the chromosomal regions on either side of the blocks of repetitive DNA within the larger acrocentric Chromosomes correspond to different rainbow trout chromosome arms provides support for this hypothesis.
Ruth B. Phillips - One of the best experts on this subject based on the ideXlab platform.
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assignment of atlantic salmon salmo salar linkage groups to specific Chromosomes conservation of large syntenic blocks corresponding to whole chromosome arms in rainbow trout oncorhynchus mykiss
BMC Genetics, 2009Co-Authors: Roy G Danzmann, Ruth B. Phillips, Kimberly A. Keatley, Matthew R. Morasch, Abigail B. Ventura, Krzysztof P. Lubieniecki, Ben F. Koop, William S. DavidsonAbstract:Most teleost species, especially freshwater groups such as the Esocidae which are the closest relatives of salmonids, have a karyotype comprising 25 pairs of acrocentric Chromosomes and 48–52 chromosome arms. After the common ancestor of salmonids underwent a whole genome duplication, its karyotype would have 100 chromosome arms, and this is reflected in the modal range of 96–104 seen in extant salmonids (e.g., rainbow trout). The Atlantic salmon is an exception among the salmonids as it has 72–74 chromosome arms and its karyotype includes 12 pairs of large acrocentric Chromosomes, which appear to be the result of tandem fusions. The purpose of this study was to integrate the Atlantic salmon's linkage map and karyotype and to compare the chromosome map with that of rainbow trout. The Atlantic salmon genetic linkage groups were assigned to specific Chromosomes in the European subspecies using fluorescence in situ hybridization with BAC probes containing genetic markers mapped to each linkage group. The genetic linkage groups were larger for Metacentric Chromosomes compared to acrocentric Chromosomes of similar size. Comparison of the Atlantic salmon chromosome map with that of rainbow trout provides strong evidence for conservation of large syntenic blocks in these species, corresponding to entire chromosome arms in the rainbow trout. It had been suggested that some of the large acrocentric Chromosomes in Atlantic salmon are the result of tandem fusions, and that the small blocks of repetitive DNA in the middle of the arms represent the sites of chromosome fusions. The finding that the chromosomal regions on either side of the blocks of repetitive DNA within the larger acrocentric Chromosomes correspond to different rainbow trout chromosome arms provides support for this hypothesis.
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Assignment of Atlantic salmon ( Salmo salar) linkage groups to specific Chromosomes: Conservation of large syntenic blocks corresponding to whole chromosome arms in rainbow trout ( Oncorhynchus mykiss )
BMC Genetics, 2009Co-Authors: Ruth B. Phillips, Roy G Danzmann, Kimberly A. Keatley, Matthew R. Morasch, Abigail B. Ventura, Krzysztof P. Lubieniecki, Ben F. Koop, William S. DavidsonAbstract:Background: Most teleost species, especially freshwater groups such as the Esocidae which are the closest relatives of salmonids, have a karyotype comprising 25 pairs of acrocentric Chromosomes and 48– 52 chromosome arms. After the common ancestor of salmonids underwent a whole genome duplication, its karyotype would have 100 chromosome arms, and this is reflected in the modal range of 96–104 seen in extant salmonids (e.g., rainbow trout). The Atlantic salmon is an exception among the salmonids as it has 72–74 chromosome arms and its karyotype includes 12 pairs of large acrocentric Chromosomes, which appear to be the result of tandem fusions. The purpose of this study was to integrate the Atlantic salmon's linkage map and karyotype and to compare the chromosome map with that of rainbow trout. Results: The Atlantic salmon genetic linkage groups were assigned to specific Chromosomes in the European subspecies using fluorescence in situ hybridization with BAC probes containing genetic markers mapped to each linkage group. The genetic linkage groups were larger for Metacentric Chromosomes compared to acrocentric Chromosomes of similar size. Comparison of the Atlantic salmon chromosome map with that of rainbow trout provides strong evidence for conservation of large syntenic blocks in these species, corresponding to entire chromosome arms in the rainbow trout. Conclusion: It had been suggested that some of the large acrocentric Chromosomes in Atlantic salmon are the result of tandem fusions, and that the small blocks of repetitive DNA in the middle of the arms represent the sites of chromosome fusions. The finding that the chromosomal regions on either side of the blocks of repetitive DNA within the larger acrocentric Chromosomes correspond to different rainbow trout chromosome arms provides support for this hypothesis.
William S. Davidson - One of the best experts on this subject based on the ideXlab platform.
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assignment of atlantic salmon salmo salar linkage groups to specific Chromosomes conservation of large syntenic blocks corresponding to whole chromosome arms in rainbow trout oncorhynchus mykiss
BMC Genetics, 2009Co-Authors: Roy G Danzmann, Ruth B. Phillips, Kimberly A. Keatley, Matthew R. Morasch, Abigail B. Ventura, Krzysztof P. Lubieniecki, Ben F. Koop, William S. DavidsonAbstract:Most teleost species, especially freshwater groups such as the Esocidae which are the closest relatives of salmonids, have a karyotype comprising 25 pairs of acrocentric Chromosomes and 48–52 chromosome arms. After the common ancestor of salmonids underwent a whole genome duplication, its karyotype would have 100 chromosome arms, and this is reflected in the modal range of 96–104 seen in extant salmonids (e.g., rainbow trout). The Atlantic salmon is an exception among the salmonids as it has 72–74 chromosome arms and its karyotype includes 12 pairs of large acrocentric Chromosomes, which appear to be the result of tandem fusions. The purpose of this study was to integrate the Atlantic salmon's linkage map and karyotype and to compare the chromosome map with that of rainbow trout. The Atlantic salmon genetic linkage groups were assigned to specific Chromosomes in the European subspecies using fluorescence in situ hybridization with BAC probes containing genetic markers mapped to each linkage group. The genetic linkage groups were larger for Metacentric Chromosomes compared to acrocentric Chromosomes of similar size. Comparison of the Atlantic salmon chromosome map with that of rainbow trout provides strong evidence for conservation of large syntenic blocks in these species, corresponding to entire chromosome arms in the rainbow trout. It had been suggested that some of the large acrocentric Chromosomes in Atlantic salmon are the result of tandem fusions, and that the small blocks of repetitive DNA in the middle of the arms represent the sites of chromosome fusions. The finding that the chromosomal regions on either side of the blocks of repetitive DNA within the larger acrocentric Chromosomes correspond to different rainbow trout chromosome arms provides support for this hypothesis.
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Assignment of Atlantic salmon ( Salmo salar) linkage groups to specific Chromosomes: Conservation of large syntenic blocks corresponding to whole chromosome arms in rainbow trout ( Oncorhynchus mykiss )
BMC Genetics, 2009Co-Authors: Ruth B. Phillips, Roy G Danzmann, Kimberly A. Keatley, Matthew R. Morasch, Abigail B. Ventura, Krzysztof P. Lubieniecki, Ben F. Koop, William S. DavidsonAbstract:Background: Most teleost species, especially freshwater groups such as the Esocidae which are the closest relatives of salmonids, have a karyotype comprising 25 pairs of acrocentric Chromosomes and 48– 52 chromosome arms. After the common ancestor of salmonids underwent a whole genome duplication, its karyotype would have 100 chromosome arms, and this is reflected in the modal range of 96–104 seen in extant salmonids (e.g., rainbow trout). The Atlantic salmon is an exception among the salmonids as it has 72–74 chromosome arms and its karyotype includes 12 pairs of large acrocentric Chromosomes, which appear to be the result of tandem fusions. The purpose of this study was to integrate the Atlantic salmon's linkage map and karyotype and to compare the chromosome map with that of rainbow trout. Results: The Atlantic salmon genetic linkage groups were assigned to specific Chromosomes in the European subspecies using fluorescence in situ hybridization with BAC probes containing genetic markers mapped to each linkage group. The genetic linkage groups were larger for Metacentric Chromosomes compared to acrocentric Chromosomes of similar size. Comparison of the Atlantic salmon chromosome map with that of rainbow trout provides strong evidence for conservation of large syntenic blocks in these species, corresponding to entire chromosome arms in the rainbow trout. Conclusion: It had been suggested that some of the large acrocentric Chromosomes in Atlantic salmon are the result of tandem fusions, and that the small blocks of repetitive DNA in the middle of the arms represent the sites of chromosome fusions. The finding that the chromosomal regions on either side of the blocks of repetitive DNA within the larger acrocentric Chromosomes correspond to different rainbow trout chromosome arms provides support for this hypothesis.
Kimberly A. Keatley - One of the best experts on this subject based on the ideXlab platform.
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assignment of atlantic salmon salmo salar linkage groups to specific Chromosomes conservation of large syntenic blocks corresponding to whole chromosome arms in rainbow trout oncorhynchus mykiss
BMC Genetics, 2009Co-Authors: Roy G Danzmann, Ruth B. Phillips, Kimberly A. Keatley, Matthew R. Morasch, Abigail B. Ventura, Krzysztof P. Lubieniecki, Ben F. Koop, William S. DavidsonAbstract:Most teleost species, especially freshwater groups such as the Esocidae which are the closest relatives of salmonids, have a karyotype comprising 25 pairs of acrocentric Chromosomes and 48–52 chromosome arms. After the common ancestor of salmonids underwent a whole genome duplication, its karyotype would have 100 chromosome arms, and this is reflected in the modal range of 96–104 seen in extant salmonids (e.g., rainbow trout). The Atlantic salmon is an exception among the salmonids as it has 72–74 chromosome arms and its karyotype includes 12 pairs of large acrocentric Chromosomes, which appear to be the result of tandem fusions. The purpose of this study was to integrate the Atlantic salmon's linkage map and karyotype and to compare the chromosome map with that of rainbow trout. The Atlantic salmon genetic linkage groups were assigned to specific Chromosomes in the European subspecies using fluorescence in situ hybridization with BAC probes containing genetic markers mapped to each linkage group. The genetic linkage groups were larger for Metacentric Chromosomes compared to acrocentric Chromosomes of similar size. Comparison of the Atlantic salmon chromosome map with that of rainbow trout provides strong evidence for conservation of large syntenic blocks in these species, corresponding to entire chromosome arms in the rainbow trout. It had been suggested that some of the large acrocentric Chromosomes in Atlantic salmon are the result of tandem fusions, and that the small blocks of repetitive DNA in the middle of the arms represent the sites of chromosome fusions. The finding that the chromosomal regions on either side of the blocks of repetitive DNA within the larger acrocentric Chromosomes correspond to different rainbow trout chromosome arms provides support for this hypothesis.
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Assignment of Atlantic salmon ( Salmo salar) linkage groups to specific Chromosomes: Conservation of large syntenic blocks corresponding to whole chromosome arms in rainbow trout ( Oncorhynchus mykiss )
BMC Genetics, 2009Co-Authors: Ruth B. Phillips, Roy G Danzmann, Kimberly A. Keatley, Matthew R. Morasch, Abigail B. Ventura, Krzysztof P. Lubieniecki, Ben F. Koop, William S. DavidsonAbstract:Background: Most teleost species, especially freshwater groups such as the Esocidae which are the closest relatives of salmonids, have a karyotype comprising 25 pairs of acrocentric Chromosomes and 48– 52 chromosome arms. After the common ancestor of salmonids underwent a whole genome duplication, its karyotype would have 100 chromosome arms, and this is reflected in the modal range of 96–104 seen in extant salmonids (e.g., rainbow trout). The Atlantic salmon is an exception among the salmonids as it has 72–74 chromosome arms and its karyotype includes 12 pairs of large acrocentric Chromosomes, which appear to be the result of tandem fusions. The purpose of this study was to integrate the Atlantic salmon's linkage map and karyotype and to compare the chromosome map with that of rainbow trout. Results: The Atlantic salmon genetic linkage groups were assigned to specific Chromosomes in the European subspecies using fluorescence in situ hybridization with BAC probes containing genetic markers mapped to each linkage group. The genetic linkage groups were larger for Metacentric Chromosomes compared to acrocentric Chromosomes of similar size. Comparison of the Atlantic salmon chromosome map with that of rainbow trout provides strong evidence for conservation of large syntenic blocks in these species, corresponding to entire chromosome arms in the rainbow trout. Conclusion: It had been suggested that some of the large acrocentric Chromosomes in Atlantic salmon are the result of tandem fusions, and that the small blocks of repetitive DNA in the middle of the arms represent the sites of chromosome fusions. The finding that the chromosomal regions on either side of the blocks of repetitive DNA within the larger acrocentric Chromosomes correspond to different rainbow trout chromosome arms provides support for this hypothesis.
