The Experts below are selected from a list of 129 Experts worldwide ranked by ideXlab platform
David Sankoff - One of the best experts on this subject based on the ideXlab platform.
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CPM - Efficient Bounds for Oriented Chromosome Inversion Distance
Combinatorial Pattern Matching, 1994Co-Authors: John Kececioglu, David SankoffAbstract:We study the problem of comparing two circular Chromosomes that have evolved by Chromosome Inversion, assuming that the order of corresponding genes is known, as well as their orientation. Determining the minimum number of Inversions is equivalent to finding the minimum of reversals to sort a signed circular permutation, where a reversal takes an arbitrary substring of elements and reverses their order, as well as flipping their sign. We show that tight bounds on the minimum number of reversals can be found by simple and efficient algorithms.
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efficient bounds for oriented Chromosome Inversion distance
Combinatorial Pattern Matching, 1994Co-Authors: John Kececioglu, David SankoffAbstract:We study the problem of comparing two circular Chromosomes that have evolved by Chromosome Inversion, assuming that the order of corresponding genes is known, as well as their orientation. Determining the minimum number of Inversions is equivalent to finding the minimum of reversals to sort a signed circular permutation, where a reversal takes an arbitrary substring of elements and reverses their order, as well as flipping their sign. We show that tight bounds on the minimum number of reversals can be found by simple and efficient algorithms.
Renee H Martin - One of the best experts on this subject based on the ideXlab platform.
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Unusual segregation products in sperm from a pericentric Inversion 17 heterozygote
Human Genetics, 2005Co-Authors: Monica M. Mikhaail-philips, Evelyn Ko, Judy Chernos, Alfred W Rademaker, Barbara C. Mcgillivray, Sara J. Hamilton, Renee H MartinAbstract:Chromosome segregation and interchromosomal effect were studied in spermatozoa from a carrier of a pericentric Chromosome 17 Inversion, 46,XY,inv(17)(p13.1q25.3). Sperm Chromosome segregation, lymphocytes of the Inversion carrier, and cells from his offspring were analysed by multicolour fluorescence in situ hybridization. The frequency of balanced sperm was 73%. An unusual segregation of recombinants was observed, viz. deletion of the p arm (14.6%) or duplication of the p arm with the presence of one q arm (8.4%), instead of the expected recombinants, viz. duplication of one arm with deletion of the other and vice versa. These unusual recombinants were explained by the position of the 17q breakpoint, which was between the q arm telomere-associated repeats and the unique q subtelomere region. The offspring of the donor were found to have a 17p deletion including the Miller-Dieker critical region, similar to the most frequent recombinant sperm class. The disomy frequency was significantly increased for Chromosome 17 compared with other autosomes, suggesting that pairing and recombination of the Inversion may predispose to non-disjunction. There was no significant difference between the frequencies of aneuploidy for Chromosomes 13, 21, X and Y in the Chromosome Inversion heterozygote compared with controls. Thus, this unique pericentric Inversion of Chromosome 17 produces unusual recombinant products; no evidence was apparent of an interchromosomal effect in any of the tested Chromosomes.
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analysis of Chromosome segregation in sperm from a Chromosome 2 Inversion heterozygote and assessment of an interchromosomal effect
American Journal of Medical Genetics Part A, 2004Co-Authors: M Mikhaailphilips, Evelyn Ko, Judy Chernos, Calvin Greene, Alfred W Rademaker, Renee H MartinAbstract:Using fluorescence in situ hybridization (FISH) analysis, the Chromosome segregation of a pericentric Inversion of Chromosome 2 was studied in spermatozoa. An interchromosomal effect (ICE) was also determined for Chromosomes 13, 21, X, and Y. This Chromosome Inversion included more than 2/3 of the total length of the Chromosome and the breaks points were in G-light bands. The frequency of non-recombinant sperm was 55.9%, and that of recombinant sperm was 34.5% (with a 1:1 ratio of duplication of the p arm and deletion of the q arm and vice versa). There was a significantly increased frequency of disomy for Chromosome 2 (0.6%) compared to the other autosomes, suggesting that pairing and recombination of the Inversion may predispose to nondisjunction. There was no significant difference between the frequencies of aneuploidy for Chromosomes 13, 21, X, and Y for the Chromosome Inversion heterozygote compared to control donors. Thus we did not find evidence for an ICE. © 2004 Wiley-Liss, Inc.
R Desalle - One of the best experts on this subject based on the ideXlab platform.
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polytene Chromosomes as indicators of phylogeny in several species groups of drosophila
BMC Evolutionary Biology, 2001Co-Authors: Patrick M Ogrady, Richard H Baker, Celeste M Durando, William J Etges, R DesalleAbstract:Background: Polytene Chromosome banding patterns have long been used by Drosophila evolutionists to infer degree of relatedness among taxa. Recently, nucleotide sequences have preempted this traditional method. We place the classical Drosophila evolutionary biology tools of polytene Chromosome Inversion analysis in a phylogenetic context and assess their utility in comparison to nucleotide sequences. Results: A simultaneous analysis framework was used to examine the congruence of the chromosomal Inversion data with more recent DNA sequence data in four Drosophila species groups – the melanogaster, virilis, repleta, and picture wing. Inversions and nucleotides were highly congruent with one another based on incongruence length difference and partitioned Bremer support values. Inversion phylogenies were less resolved because of fewer numbers of characters. Partitioned Bremer supports, corrected for the number of characters in each matrix, were higher for Inversion matrices. Conclusions: Polytene Chromosome data are highly congruent with DNA sequence data and, when placed in a simultaneous analysis framework, are shown to be more information rich than nucleotide data.
Celeste M Durando - One of the best experts on this subject based on the ideXlab platform.
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polytene Chromosomes as indicators of phylogeny in several species groups of drosophila
BMC Evolutionary Biology, 2001Co-Authors: Patrick M Ogrady, Richard H Baker, Celeste M Durando, William J Etges, R DesalleAbstract:Background: Polytene Chromosome banding patterns have long been used by Drosophila evolutionists to infer degree of relatedness among taxa. Recently, nucleotide sequences have preempted this traditional method. We place the classical Drosophila evolutionary biology tools of polytene Chromosome Inversion analysis in a phylogenetic context and assess their utility in comparison to nucleotide sequences. Results: A simultaneous analysis framework was used to examine the congruence of the chromosomal Inversion data with more recent DNA sequence data in four Drosophila species groups – the melanogaster, virilis, repleta, and picture wing. Inversions and nucleotides were highly congruent with one another based on incongruence length difference and partitioned Bremer support values. Inversion phylogenies were less resolved because of fewer numbers of characters. Partitioned Bremer supports, corrected for the number of characters in each matrix, were higher for Inversion matrices. Conclusions: Polytene Chromosome data are highly congruent with DNA sequence data and, when placed in a simultaneous analysis framework, are shown to be more information rich than nucleotide data.
Mark Kirkpatrick - One of the best experts on this subject based on the ideXlab platform.
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Invasion Genetics - Chromosome Inversions, adaptive cassettes and the evolution of species' ranges
Molecular Ecology, 2015Co-Authors: Mark Kirkpatrick, Brian BarrettAbstract:: A Chromosome Inversion can spread when it captures locally adapted alleles or when it is introduced into a species by hybridization with adapted alleles that were previously absent. We present a model that shows how both processes can cause a species range to expand. Introgression of an Inversion that carries novel, locally adapted alleles is a particularly powerful mechanism for range expansion. The model supports the earlier proposal that introgression of an Inversion triggered a large range expansion of a malaria mosquito. These results suggest a role for Inversions as cassettes of genes that can accelerate adaptation by crossing species boundaries, rather than protecting genomes from introgression.
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reproductive isolation and local adaptation quantified for a Chromosome Inversion in a malaria mosquito
Evolution, 2013Co-Authors: Rafael F Guerrero, Diego Ayala, Mark KirkpatrickAbstract:: Chromosome Inversions have long been thought to be involved in speciation and local adaptation. We have little quantitative information, however, about the effects that Inversion polymorphisms have on reproductive isolation and viability. Here we provide the first estimates from any organism for the total amount of reproductive isolation associated with an Inversion segregating in natural populations. We sampled Chromosomes from 751 mosquitoes of the malaria vector Anopheles funestus along a 1421 km transect in Cameroon that traverses savannah, highland, and rainforest ecological zones. We then developed a series of population genetic models that account for selection, migration, and assortative mating, and fit the models to the data using likelihood. Results from the best-fit models suggest there is strong local adaptation, with relative viabilities of homozygotes ranging from 25% to 130% compared to heterozygotes. Viabilities vary qualitatively between regions: the Inversion is underdominant in the savannah, whereas in the highlands it is overdominant. The Inversion is also implicated in strong assortative mating. In the savannah, the two homozygote forms show 92% reproductive isolation, suggesting that this one Inversion can generate most of the genetic barriers needed for speciation.