ABSTRACT
Monosomic alien addition lines (MAALs) are useful for assigning linkage groups to chromosomes. We examined whether the chromosomal rearrangements following the introduction of a single onion (Allium cepa) chromosome into the Allium fistulosum genome were produced by homeologous crossing over or by a nonreciprocal conversion event. Among the monosomic lines available, 17 were studied by fluorescent genomic in situ hybridisation, using total A. cepa genomic DNA as the probe and total A. fistulosum genomic DNA as the competitor. In this way, rearrangements such as chromosomal translocations between A. cepa and A. fistulosum were identified as terminal regions consisting of tandem DNA repeats. Homeologous crossing over between the two closely related genomes occurred in 4 of the 17 lines, suggesting that such events are not rare. On the basis of a detailed molecular cytogenetic characterisation, we identified true monosomic alien addition lines for A. cepa chromosomes 3, 4, 5, 7, and 8 that can reliably be used in genetic studies.
Subject(s)
Allium/genetics , Recombination, Genetic , Chromosomes , Cytogenetic Analysis , Gene Rearrangement , Hybridization, Genetic/genetics , In Situ Hybridization, Fluorescence , Karyotyping , MonosomyABSTRACT
Water shortage produced an early and large stimulation of acid-soluble invertase activity in adult maize leaves whereas cell wall invertase activity remained constant. This response was closely related to the mRNA level for only one of the invertase gene (Ivr2), encoding a vacuolar isoform. In parallel, four quantitative trait loci (QTLs) were detected for invertase activity under control and nine under stressful conditions. One QTL in control and one in stressed plants was located near to the Ivr2 gene on chromosome 5. Other QTLs for invertase activity were found close to carbohydrate QTLs; some of them formed 'stress clusters'.
Subject(s)
Gene Expression Regulation, Plant , Glycoside Hydrolases/genetics , Quantitative Trait, Heritable , Water , Zea mays/enzymology , DNA, Plant/chemistry , Plant Leaves/enzymology , Plant Leaves/genetics , RNA, Messenger/metabolism , RNA, Plant/metabolism , Vacuoles/enzymology , Zea mays/genetics , beta-FructofuranosidaseABSTRACT
GENERAL CHARACTERISTICS: Several criteria are used for coronary stent design: biocompatibility, i.e. the capacity to resist thrombotic events and corrosion, flexibility, radial force sufficient to resist elastic recoil, percentage of the lesion covered, radio-opacity, minimal shortening at opening, absence of effect on collateral branches, possibility to use small calibre probe guides, and cost. TWO CATEGORIES: Both tubular stents (self-expanding stents and balloon stents) and filamentary stents (made of stainless steel or tantalum) are used, THE IDEAL STENT: There is no one ideal stent. Choice is dictated by the characteristics of the lesion and by the status of the artery to treat.
