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  • 1
    ISSN: 1432-2242
    Schlagwort(e): Tomato ; RFLP ; rDNA ; Tobacco mosaic virus ; Introgression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We studied rDNA restriction fragment length polymorphism between two tomato lines used for F1 hybrid seed production: line A, containing the Tm-1 gene responsible for tobacco mosaic virus tolerance introgressed from the wild species Lycopersicon hirsutum, and line B, a tobacco mosaic virus sensitive line. Hybridization patterns led to distinct rDNA maps with two size classes, 10.4 and 10.7 kb, in line A and a single, 8.9-kb class in line B. Size differences were located in the intergenie sequence (IGS). A highly specific 54-bp TaqI fragment was cloned from the line A IGS and used in dot blot experiments to probe total DNA from line A, line B, and their F1 hybrid. It proved capable of discriminating B from A and the hybrid. This probe could thus serve to screen inbreds in commercial seed lots where line A is used as male. This fragment showed 80–90% sequence homology with the 53-bp subrepeats previously characterized in a region of the tomato IGS close to the 25S rRNA gene. Preliminary comparison of rDNA in line A and several wild related species indicated that the L. hirsutum H2 genotype was the closest to line A. rDNA variations between line A and this wild genotype could be explained by recombination during the introgression process involving numerous backcrosses or by an important intraspecific polymorphism. Our results strongly suggest that Tm-1 and the rDNA were introgressed together into tomato from L. hirsutum through linkage drag.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 91 (1995), S. 505-509 
    ISSN: 1432-2242
    Schlagwort(e): Chloroplast DNA ; Mitochondrial DNA ; rDNA ; RFLP ; Witloof chicory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Restriction fragment length polymorphisms of cytoplasmic DNAs and nuclear rDNA were analyzed in several Cichorium intybus genotypes, comprising four white inbred lines, eight red witloof experimental lines, and a number of F1 hybrids derived from two white parents. Chloroplast and mitochondrial restriction patterns led to the distinction between two different cytoplasms, called I and II. Southern hybridization using a nuclear rDNA probe revealed that all the lines possessed two types of rDNA repeat units. The shortest unit was 10 kb and was common to all lines. The largest rDNA repeat unit was 10.5 kb in lines I and 10.4 kb in lines II. In addition, a sequence heterogeneity between the 10.5 and 10.4-kb rDNA repeat units was revealed by Sac I digestion. A 10-kb rDNA unit was successively cloned, mapped, and used as a probe to check the genetic purity of F1 hybrid seeds between line I and II white parents. We found a 30% average percentage of impurities, originating both from selfing and full-sib crossing, in different open-pollinated hybrid samples.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Diabetologia 37 (1994), S. 552-558 
    ISSN: 1432-0428
    Schlagwort(e): Autoimmunity ; immunotherapy ; suppressor cells ; insulitis ; vitamin D analogues
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary 1,25 dihydroxyvitamin D3, the active form of vitamin D, has immunomodulatory properties in vitro and in vivo. We report that treatment with 1,25 dihydroxyvitamin D3 (5 μg/kg on alternate days) prevents the development of clinical diabetes in NOD mice, an animal model of human autoimmune diabetes. Diabetes incidence in female NOD mice at the age of 200 days was reduced to 8% in the 1,25 dihydroxyvitamin D treated group vs 56% in the control group (p〈0.0001). In parallel, treatment with 1,25 dihydroxyvitamin D3 resulted in a complete normalisation of the capacity to induce suppressor mechanisms in an autologous MLR, which is severely depressed in control NOD mice. The existence of such suppressor cells was confirmed in transfer experiments, whereby cotransfer of splenocytes from 1,25 dihydroxyvitamin D3 treated NOD mice prevented diabetes transfer by splenocytes from diabetic NOD mice into irradiated, 6–8-week-old male NOD mice. Other known immune defects of the NOD mice, such as defective natural killer cell killing of YAC-1 targets and defective thymocyte activation by anti-CD3 were not corrected. The pharmacological doses of 1,25 dihydroxyvitamin D3 were universally well tolerated as reflected by a normal weight gain of the mice. Serum calcium was increased (2.5±0.2 vs 2.2±0.2 mmol/l in the control group, P〈0.005), whereas osteocalcin levels nearly doubled and bone calcium content was halved. These findings show that 1,25 dihydroxyvitamin D3 can prevent diabetes in NOD mice, probably through the correction of their defective suppressor function.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 75 (1988), S. 546-552 
    ISSN: 1432-2242
    Schlagwort(e): Brassica napus ; Brassica hirta ; Somatic hybridization ; mtDNA ; ctDNA ; rDNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Somatic hybridization between Brassica napus and B. hirta (or Sinapis alba) is described. No cybrid plant with B. napus nucleus exhibiting cytoplasmic male sterility was recovered. Somatic hybrids were identified morphologically and, for some of them, by cytological observations. They were also characterised by Southern hybridization of nuclear rDNA. Chloroplast and mitochondrial DNA restriction analysis showed that 2 plants out of 14 have B. hirta ctDNA, one the B. napus mtDNA and the other a hybrid. Nine possess B. napus ctDNA with a hybrid mtDNA. For six of them, mtDNA patterns present novel bands, suggesting intergenomic recombination during fusion. These hybrids will be included in the breeding program.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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