The Experts below are selected from a list of 1719 Experts worldwide ranked by ideXlab platform
Edwin H. Goodwin - One of the best experts on this subject based on the ideXlab platform.
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Transmission of radiation-induced Acentric chromosomal Fragments to micronuclei in normal human fibroblasts.
Radiation research, 1991Co-Authors: Michael N. Cornforth, Edwin H. GoodwinAbstract:A simplifying assumption made when calculating the probability of a chromosomal aberration resulting in a micronucleus is that virtually all radiation-induced micronuclei result from Acentric Fragments. In the present study we used antibodies to chromosomal centromeres (kinetochores) to determine the frequency of centric versus Acentric micronuclei in normal human fibroblasts exposed to 6 Gy of60 Co γ rays while they were in density-inhibited growth. Up to 14% of the micronuclei induced by this exposure contained one or more kinetochores; i.e., they were not composed of Acentric chromatin. By deleting kinetochore-positive micronuclei from the analysis, and by reconstructing micronucleus frequencies based on the fraction of cells that had divided following radiation exposure, a direct comparison between micronuclei and Acentric chromosome Fragments was made. On that basis, the probability of an Acentric Fragment becoming a visible micronucleus in either daughter cell of a dividing pair was estimated to be ...
Jonathan D G Jones - One of the best experts on this subject based on the ideXlab platform.
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aberrant transpositions of maize double ds like elements usually involve ds ends on sister chromatids
The Plant Cell, 1995Co-Authors: James J English, Kate Harrison, Jonathan D G JonesAbstract:McClintock9s analysis of chromosome-breaking Dissociation (Ds) elements in maize demonstrated that sister chromatids fuse at the position of Ds, forming a dicentric chromosome and an Acentric Fragment. In tobacco, Ds left and right ends in direct orientation (that is, half a double Ds) are sufficient to promote Activator-dependent marker gene loss. We present here a detailed analysis of germinally inherited rearrangements promoted by "half double Ds" elements and a characterization of rearrangements that involve inversion of the segment between the Ds ends and/or deletion of a segment adjacent to the Ds construct. The results support a model in which chromosome breakage promoted by these elements, and presumably by double Ds elements, involves Ds ends on sister chromatids.
Michael N. Cornforth - One of the best experts on this subject based on the ideXlab platform.
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Transmission of radiation-induced Acentric chromosomal Fragments to micronuclei in normal human fibroblasts.
Radiation research, 1991Co-Authors: Michael N. Cornforth, Edwin H. GoodwinAbstract:A simplifying assumption made when calculating the probability of a chromosomal aberration resulting in a micronucleus is that virtually all radiation-induced micronuclei result from Acentric Fragments. In the present study we used antibodies to chromosomal centromeres (kinetochores) to determine the frequency of centric versus Acentric micronuclei in normal human fibroblasts exposed to 6 Gy of60 Co γ rays while they were in density-inhibited growth. Up to 14% of the micronuclei induced by this exposure contained one or more kinetochores; i.e., they were not composed of Acentric chromatin. By deleting kinetochore-positive micronuclei from the analysis, and by reconstructing micronucleus frequencies based on the fraction of cells that had divided following radiation exposure, a direct comparison between micronuclei and Acentric chromosome Fragments was made. On that basis, the probability of an Acentric Fragment becoming a visible micronucleus in either daughter cell of a dividing pair was estimated to be ...
Stuart Schwartz - One of the best experts on this subject based on the ideXlab platform.
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Inverted Duplications on Acentric Markers: Mechanism of Formation
Human molecular genetics, 2009Co-Authors: Andrea E. Murmann, Donald F. Conrad, Heather Mashek, Chris A. Curtis, Raluca Nicolae, Carole Ober, Stuart SchwartzAbstract:Acentric inverted duplication (inv dup) markers, the largest group of chromosomal abnormalities with neocentromere formation, are found in patients both with idiopathic mental retardation and with cancer. The mechanism of their formation has been investigated by analyzing the breakpoints and the genotypes of 12 inv dup marker cases (three trisomic, six tetrasomic, two polysomic and one X chromosome derived marker) using a combination of fluorescence in situ hybridization, quantitative SNP array and microsatellite analysis. Inv dup markers were found to form either symmetrically with one breakpoint or asymmetrically with two distinct breakpoints. Genotype analyses revealed that all inv dup markers formed from one single chromatid end. This observation is incompatible with the previously suggested model by which the Acentric inv dup markers form through inter-chromosomal U-type exchange. On the basis of the identification of DNA sequence motifs with inverted homologies within all observed breakpoint regions, a new general mechanism is proposed for the Acentric inv dup marker formation: following a double-strand break an Acentric Fragment forms, during either meiosis or mitosis. The open DNA end of the Acentric Fragment is stabilized by the formation of an intra-chromosomal loop promoted by the presence of sequences with inverted homologies. Likely coinciding with the neocentromere formation, this stabilized Fragment is duplicated during an early mitotic event, insuring the marker's survival during cell division and its presence in all cells.
James J English - One of the best experts on this subject based on the ideXlab platform.
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aberrant transpositions of maize double ds like elements usually involve ds ends on sister chromatids
The Plant Cell, 1995Co-Authors: James J English, Kate Harrison, Jonathan D G JonesAbstract:McClintock9s analysis of chromosome-breaking Dissociation (Ds) elements in maize demonstrated that sister chromatids fuse at the position of Ds, forming a dicentric chromosome and an Acentric Fragment. In tobacco, Ds left and right ends in direct orientation (that is, half a double Ds) are sufficient to promote Activator-dependent marker gene loss. We present here a detailed analysis of germinally inherited rearrangements promoted by "half double Ds" elements and a characterization of rearrangements that involve inversion of the segment between the Ds ends and/or deletion of a segment adjacent to the Ds construct. The results support a model in which chromosome breakage promoted by these elements, and presumably by double Ds elements, involves Ds ends on sister chromatids.
