22 Result(s)
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Article
A. R. Leitch
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Article
Open AccessNicotine in floral nectar pharmacologically influences bumblebee learning of floral features
Many plants defend themselves against herbivores by chemical deterrents in their tissues and the presence of such substances in floral nectar means that pollinators often encounter them when foraging. The effe...
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Silenced rRNA genes are activated and substitute for partially eliminated active homeologs in the recently formed allotetraploid, Tragopogon mirus (Asteraceae)
To study the relationship between uniparental rDNA (encoding 18S, 5.8S and 26S ribosomal RNA) silencing (nucleolar dominance) and rRNA gene dosage, we studied a recently emerged (within the last 80 years) allo...
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The asymmetric meiosis in pentaploid dogroses (Rosa sect. Caninae) is associated with a skewed distribution of rRNA gene families in the gametes
In pentaploid dogroses, Rosa section Caninae (2n=5x=35), the pollen transmits one basic genome (x=7) derived from the seven segregating bivalents, whereas the egg transmits four basic genomes (4x=28) one set deri...
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Conserved gene order belies rapid genome turnover: The dynamic interplay between genomic DNA and the outside world
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Evolutionary implications of permanent odd polyploidy in the stable sexual, pentaploid of Rosa canina L
In Rosa canina (2n=5x=35), the pollen and ovular parents contribute, respectively, seven and 28 chromosomes to the zygote. At meiosis I, 14 chromosomes form seven bivalents and 21 chromosomes remain as univalents...
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The origin and evolution of geminivirus-related DNA sequences in Nicotiana
A horizontal transmission of a geminiviral DNA sequence, into the germ line of an ancestral Nicotiana, gave rise to multiple repeats of geminivirus-related DNA, GRD, in the genome. We follow GRD evolution in Nico...
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Ribosomal DNA evolution and gene conversion in Nicotiana rustica
Genomic in situ hybridisation was used to confirm that Nicotiana rustica (2n=4x=48) is an allotetraploid between N. paniculata (2n=2x=24, maternal P- genome donor) and N. undulata (2n=2x=24, paternal U-genome don...
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Evolution and structure of 5S rDNA loci in allotetraploid Nicotiana tabacum and its putative parental species
Nicotiana tabacum (tobacco) is an allotetraploid derived from ancestors of the modern diploids, N. sylvestris and N. tomentosiformis. We identified and characterized two distinct families of 5S ribosomal DNA (rDN...
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Comparative analysis of DNA methylation in tobacco heterochromatic sequences
Cytosine methylation levels and susceptibility to drug-induced hypomethylation have been studied in several Nicotiana tabacum (tobacco) DNA repetitive sequences. It has been shown using HapII, MspI, BamHI and Sau...
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Aloe L. – a second plant family without (TTTAGGG)n telomeres
The physical ends of chromosomes are protected and stabilised by telomeres. The sequence of telomeric DNA normally consists of a simple repeating unit that is conserved in many organisms. Most plants examined ...
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Gene conversion of ribosomal DNA in Nicotiana tabacum is associated with undermethylated, decondensed and probably active gene units
We examined the structure, intranuclear distribution and activity of ribosomal DNA (rDNA) in Nico-tiana sylvestris (2n=2x=24) and N. tomentosiformis (2n=2x=24) and compared these with patterns in N. tabacum (toba...
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Genomic characterisation and the detection of raspberry chromatin in polyploid Rubus
This paper reports genomic in situ hybridization (GISH) and fluorescent in situ hybridization (FISH) data for chromosomes of raspberry (Rubus idaeus 2n=2x=14), blackberry (Rubus aggregate, subgenus Eubatus. 2n=2...
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Flow cytometric analysis of the chromosomes and stability of a wheat cell-culture line
A rapidly growing, long-term suspension culture derived from Triticum aestivum L. (wheat) was synchronized using hydroxyurea and colchicine, and a chromosome suspension with 2–3 × 106 chromosomes ml−1 was made. A...
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Conversion of a RAPD-generated PCR product, containing a novel dispersed repetitive element, into a fast and robust assay for the presence of rye chromatin in wheat
Bulk segregant analysis was used to obtain a random amplified polymorphic DNA (RAPD) marker specific for the rye chromosome arm of the 1BL.1RS translocation, which is common in many high-yielding bread wheat v...
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The use of fluorochromes in the cytogenetics of the small-grained cereals (Triticeae)
This paper describes some of the major advances that have been made in the cytogenetics of the small-grained cereals (Triticeae) using fluorochromes to detect nucleic acids in situ. The method, widely known as fl...
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Session 01 Cell structure and development
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Genomic in situ hybridization to identify alien chromosomes and chromosome segments in wheat
Genomic in situ hybridization was used to identify alien chromatin in chromosome spreads of wheat, Triticum aestivum L., lines incorporating chromosomes from Leymus multicaulis (Kar. and Kir.) Tzvelev and Thinopy...
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Parental genomes are separated throughout the cell cycle in a plant hybrid
The positions of the genomes originating from each parent were analysed in root-tip nuclei of the mature, sexual F1 hybrid plant Hordeum vulgare (barley) x Secale africanum (a wild rye). The two genomes of the hy...
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Chromosome arrangements in human fibroblasts at mitosis
The positions of the centromeres of all 46 human chromosomes were analysed in three dimensional reconstructions of electron micrographs of 10 serially sectioned unpretreated human male fibroblast cells. The re...
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Detection and characterization of 1B/1R translocations in hexaploid wheat
Total genomic DNA from rye was labelled with biotin and used as a probe for in situ hybridization to show the sizes and translocation points of the rye chromosome segments in five wheat varieties which carry a tr...
