Reverse transcriptase (rt) fragments from LINE retrotransposons in the mulberry genome were analyzed in terms of heterogeneity, phylogeny, and chromosomal distribution. We amplified and characterized conserved domains...Reverse transcriptase (rt) fragments from LINE retrotransposons in the mulberry genome were analyzed in terms of heterogeneity, phylogeny, and chromosomal distribution. We amplified and characterized conserved domains of the rt using degenerate primer pairs. Sequence analyses indicated that the rt fragments were highly heterogeneous and rich in A/T bases. The sequence identity ranged from 31.8% to 99.4%. Based on sequence similarities, the rt fragments were categorized into eight groups. Furthermore, similar stop codon distribution patterns among a series of clones in the same group indicated that they underwent a similar evolutionary process. Interestingly, phylogenetic analyses of the rt fragments isolated from mulberry and 13 other plant species revealed that two distantly related taxa (mulberry and Paeonia suffruticosa) grouped together. It does not appear that this phenomenon resulted from horizontal transposable element transfer. Fluorescence in situ hybridization analysis revealed that most of the rt fragments were concentrated in the subtelomeric and pericentromeric regions of the mulberry chromosomes, but that these elements were not abundant in the mulberry genome. Future studies will focus on the potential roles of these elements in the subtelomeric and pericentromeric regions of the mulberry genome.展开更多
We report the isolation of AtL1, a 249 bp non-LTR retrotransposon fragment from Arabidopsis thaliana by fingerprinting mRNAs extracted from A. thaliana plants, ecotype Columbia, in different heat stress conditions. So...We report the isolation of AtL1, a 249 bp non-LTR retrotransposon fragment from Arabidopsis thaliana by fingerprinting mRNAs extracted from A. thaliana plants, ecotype Columbia, in different heat stress conditions. Southern blot and PCR analysis suggested that AtL1 occurs as a single- or low-copy insert in the genome of A. thaliana ecotype Columbia. The presence of AtL1 in the genome of different Arabidopsis ecotypes was confirmed by PCR amplification and sequencing thus excluding all possible contamination. A preliminary scan of the AtL1 nucleotide sequence against the EMBL and NCBI databases revealed a high degree of similarity to a group of LINE type L1 retrotransposons of mammals and with a cDNA sequence of Artemisia annua. A phylogenetic analysis of LINE elements from animals and plants placed AtL1 and A. annua sequences in close proximity to some mammalian sequences but distant from the other plants LINE elements including those from Arabidopsis.展开更多
文摘Reverse transcriptase (rt) fragments from LINE retrotransposons in the mulberry genome were analyzed in terms of heterogeneity, phylogeny, and chromosomal distribution. We amplified and characterized conserved domains of the rt using degenerate primer pairs. Sequence analyses indicated that the rt fragments were highly heterogeneous and rich in A/T bases. The sequence identity ranged from 31.8% to 99.4%. Based on sequence similarities, the rt fragments were categorized into eight groups. Furthermore, similar stop codon distribution patterns among a series of clones in the same group indicated that they underwent a similar evolutionary process. Interestingly, phylogenetic analyses of the rt fragments isolated from mulberry and 13 other plant species revealed that two distantly related taxa (mulberry and Paeonia suffruticosa) grouped together. It does not appear that this phenomenon resulted from horizontal transposable element transfer. Fluorescence in situ hybridization analysis revealed that most of the rt fragments were concentrated in the subtelomeric and pericentromeric regions of the mulberry chromosomes, but that these elements were not abundant in the mulberry genome. Future studies will focus on the potential roles of these elements in the subtelomeric and pericentromeric regions of the mulberry genome.
文摘We report the isolation of AtL1, a 249 bp non-LTR retrotransposon fragment from Arabidopsis thaliana by fingerprinting mRNAs extracted from A. thaliana plants, ecotype Columbia, in different heat stress conditions. Southern blot and PCR analysis suggested that AtL1 occurs as a single- or low-copy insert in the genome of A. thaliana ecotype Columbia. The presence of AtL1 in the genome of different Arabidopsis ecotypes was confirmed by PCR amplification and sequencing thus excluding all possible contamination. A preliminary scan of the AtL1 nucleotide sequence against the EMBL and NCBI databases revealed a high degree of similarity to a group of LINE type L1 retrotransposons of mammals and with a cDNA sequence of Artemisia annua. A phylogenetic analysis of LINE elements from animals and plants placed AtL1 and A. annua sequences in close proximity to some mammalian sequences but distant from the other plants LINE elements including those from Arabidopsis.
