The Experts below are selected from a list of 12 Experts worldwide ranked by ideXlab platform
Jose Antonio Martinezizquierdo - One of the best experts on this subject based on the ideXlab platform.
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study on the evolution of the grande retrotransposon in the Zea Genus
Molecular Biology and Evolution, 2003Co-Authors: Jose L Garciamartinez, Jose Antonio MartinezizquierdoAbstract:The study of Grande retrotransposon (RTN) variation reported here comprises the intrinsic element variability and the changes that element insertion provokes in the Zea genome, including its abundance among species. Sequence analysis of a defined long-terminal repeat (LTR) region from Grande RTN revealed a high level of sequence divergence since no identical sequences were found among the 65 clones examined that belong to different Zea species or maize inbred lines. Average diversity values within accessions ranged from 0.17 to 0.37 substitutions per nucleotide. Phylogenetic analysis revealed a lack of concordance between the phylogenetic tree obtained from LTR sequences and the conventional taxonomic tree, suggesting that different subfamilies of Grande elements existed before Zea speciation. When sequence-specific amplification polymorphism (SSAP) marker data, which combines genomic and RTN variation, are used, the derived trees reflect the established species phylogeny and allow, as well, differentiating among some maize lines. Finally, the evaluation of Grande abundance, using different element probes in all the Zea species but Z. luxurians, revealed around 5,700 copies per haploid genome in all the diploid species examined, indicating a similar expansion process of Grande in all the Zea genomes. This number of copies represents in all cases around a 3% of the genome, which implies that Grande RTN is an important component of the maize genome. The copy number ratio LTR/gag is around 2 in all the species analyzed, indicating that overwhelming majority of elements have internal region. Thus, mechanisms such as homologous recombination between LTRs of a single RTN, which would remove the internal region and one LTR, leaving behind a single recombinant LTR, seems not to be active in maize for Grande RTN.
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molecular analysis of a putative transposable retroelement from the Zea Genus with internal clusters of tandem repeats
DNA Research, 1995Co-Authors: Amparo Monfort, Carlos M Vicient, Pere Puigdomenech, Jose Antonio MartinezizquierdoAbstract:The molecular characterization of a recently discovered family of long repetitive sequences, termed ZLRS, is described. These elements belong to the class of moderate dispersed repetitive DNA and are specific to the Zea Genus. An 8089-bp sequence from a Zea diploperennis ZLRS element have been elucidated. Sequence analysis reveals the presence of a long terminal repeat-like region, two clusters of different tandem repeats and several ORFs. On these grounds, ZLRS could be considered a new member of the superfamily of transposable retroelements. Tandems are present in the majority of ZLRS elements, they show an important stem-loop secondary structure predicted by the computer and their sequence conservation suggests a functional role.
Amparo Monfort - One of the best experts on this subject based on the ideXlab platform.
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molecular analysis of a putative transposable retroelement from the Zea Genus with internal clusters of tandem repeats
DNA Research, 1995Co-Authors: Amparo Monfort, Carlos M Vicient, Pere Puigdomenech, Jose Antonio MartinezizquierdoAbstract:The molecular characterization of a recently discovered family of long repetitive sequences, termed ZLRS, is described. These elements belong to the class of moderate dispersed repetitive DNA and are specific to the Zea Genus. An 8089-bp sequence from a Zea diploperennis ZLRS element have been elucidated. Sequence analysis reveals the presence of a long terminal repeat-like region, two clusters of different tandem repeats and several ORFs. On these grounds, ZLRS could be considered a new member of the superfamily of transposable retroelements. Tandems are present in the majority of ZLRS elements, they show an important stem-loop secondary structure predicted by the computer and their sequence conservation suggests a functional role.
Jose L Garciamartinez - One of the best experts on this subject based on the ideXlab platform.
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study on the evolution of the grande retrotransposon in the Zea Genus
Molecular Biology and Evolution, 2003Co-Authors: Jose L Garciamartinez, Jose Antonio MartinezizquierdoAbstract:The study of Grande retrotransposon (RTN) variation reported here comprises the intrinsic element variability and the changes that element insertion provokes in the Zea genome, including its abundance among species. Sequence analysis of a defined long-terminal repeat (LTR) region from Grande RTN revealed a high level of sequence divergence since no identical sequences were found among the 65 clones examined that belong to different Zea species or maize inbred lines. Average diversity values within accessions ranged from 0.17 to 0.37 substitutions per nucleotide. Phylogenetic analysis revealed a lack of concordance between the phylogenetic tree obtained from LTR sequences and the conventional taxonomic tree, suggesting that different subfamilies of Grande elements existed before Zea speciation. When sequence-specific amplification polymorphism (SSAP) marker data, which combines genomic and RTN variation, are used, the derived trees reflect the established species phylogeny and allow, as well, differentiating among some maize lines. Finally, the evaluation of Grande abundance, using different element probes in all the Zea species but Z. luxurians, revealed around 5,700 copies per haploid genome in all the diploid species examined, indicating a similar expansion process of Grande in all the Zea genomes. This number of copies represents in all cases around a 3% of the genome, which implies that Grande RTN is an important component of the maize genome. The copy number ratio LTR/gag is around 2 in all the species analyzed, indicating that overwhelming majority of elements have internal region. Thus, mechanisms such as homologous recombination between LTRs of a single RTN, which would remove the internal region and one LTR, leaving behind a single recombinant LTR, seems not to be active in maize for Grande RTN.
Carlos M Vicient - One of the best experts on this subject based on the ideXlab platform.
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What makes Grande1 retrotransposon different?
Genetica, 1997Co-Authors: José A. Martínez-izquierdo, José García-martínez, Carlos M VicientAbstract:Grande1 elements constitute a family of Ty3 retrotransposons present in the Zea Genus in more than 1000 copies in Zea diploperennis and maize. The sequences of three Grande1 flanking regions, two from Z. diploperennis and one from maize, reveal transposable elements as insertion targets, suggesting a preferential integration of Grande1 elements into other transposable elements. These retrotransposons are remarkable for their large size of around 14 kb, which is a consequence of a very large 3′ region of more than 7 kb. Atypical entities within this region are two arrays of unrelated tandem repeats with potential stable stem-loop structures. A large portion of the same region is occupied by ORFs, although only ORF23, whose function is unknown, is presumably transcribed in antisense orientation to the reverse transcriptase ORF. Only ORF23 has a codon usage similar to the one tabulated for highly-expressed maize genes. Correspondingly, the transcript of 900 b that hybridizes with ORF23 probes is found in all the maize tissues explored. This is despite the high level of methylation in the DNA of Grande1. Genomic RNA has not been detected in any tissue or situation studied, probably reflecting a non-functional retrotransposon. The origin of ORF23 and the remainder 3′ region might be due to a transduction event.
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molecular analysis of a putative transposable retroelement from the Zea Genus with internal clusters of tandem repeats
DNA Research, 1995Co-Authors: Amparo Monfort, Carlos M Vicient, Pere Puigdomenech, Jose Antonio MartinezizquierdoAbstract:The molecular characterization of a recently discovered family of long repetitive sequences, termed ZLRS, is described. These elements belong to the class of moderate dispersed repetitive DNA and are specific to the Zea Genus. An 8089-bp sequence from a Zea diploperennis ZLRS element have been elucidated. Sequence analysis reveals the presence of a long terminal repeat-like region, two clusters of different tandem repeats and several ORFs. On these grounds, ZLRS could be considered a new member of the superfamily of transposable retroelements. Tandems are present in the majority of ZLRS elements, they show an important stem-loop secondary structure predicted by the computer and their sequence conservation suggests a functional role.
Pere Puigdomenech - One of the best experts on this subject based on the ideXlab platform.
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molecular analysis of a putative transposable retroelement from the Zea Genus with internal clusters of tandem repeats
DNA Research, 1995Co-Authors: Amparo Monfort, Carlos M Vicient, Pere Puigdomenech, Jose Antonio MartinezizquierdoAbstract:The molecular characterization of a recently discovered family of long repetitive sequences, termed ZLRS, is described. These elements belong to the class of moderate dispersed repetitive DNA and are specific to the Zea Genus. An 8089-bp sequence from a Zea diploperennis ZLRS element have been elucidated. Sequence analysis reveals the presence of a long terminal repeat-like region, two clusters of different tandem repeats and several ORFs. On these grounds, ZLRS could be considered a new member of the superfamily of transposable retroelements. Tandems are present in the majority of ZLRS elements, they show an important stem-loop secondary structure predicted by the computer and their sequence conservation suggests a functional role.
