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  • 1
    ISSN: 1432-2242
    Keywords: Repeated DNA ; Restriction satellite ; RFLP ; Solanaceae ; Species-specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Highly repeated DNA of potato (Solanum sp.) was characterized by cloning various major repeated elements of the nuclear genome. The percentage of the nuclear genome of the specific fractions and the restriction enzyme patterns were determined in order to show the distribution and organization of the respective repeats in the genome of Solanum tuberosum cultivars, dihaploid breeding lines and in wild species of Solanum. Several of the clones obtained were represented in a high copy number but showed no informative RFLP patterns. More information was gained from ‘restriction satellite’ repeats. The clone pR1T320 was found to contain satellite repeats (360 bp in length) that are proportionally present in the genome of all Solanum species at frequencies, between 0.5% and 2.6% and which are differently organized. This repeat was also found in the genera Lycopersicon, Datura and Nicotiana. With various restriction enzymes characteristic RFLP patterns were detected. A more or less genus-specific element for Solanum was the 183-bp repeat (clone pSA287; between 0.2–0.4% of the nuclear genome) that was present in the majority of the Solanum species analyzed except S. kurtzianum, S. bulbocastanum and S. pinnatisectum. In a few wild species (prominently in S. kurtzianum, S. demissum and S. acaule) a specific repeat type was detected (clone pSDT382; repeat length approximately 370 bp) that could be used to trace the wild species introduced into S. tuberosum cultivars. The repeats analyzed together with the 18S, 5.8S and 25S ribosomal DNA (1.9–5.2%, corresponding to 1800-5500 rDNA copies) comprised approximately 4–7% of the Solanum genome.
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  • 2
    ISSN: 1432-2242
    Keywords: Hordeum vulgare ; Rhynchosporium secalis ; Scald ; Resistance gene Rh2 ; Restriction fragment length polymorphism (RFLP)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhynchosporium secalis is the causal organism of barley scald disease. A number of resistance genes against the fungus are well known; one of them, the single dominant Rh2 resistance gene, has been mapped on the linkage map of barley using RFLP (restriction fragment length polymorphism) markers. The Rh2 gene was located on the distal part of chromosome arm 1S co-segregating with the RFLP marker CDO545 in 85 doubled-haploid progeny plants. The spring barley test population used was a cross between the 6-rowed American spring barley cv Atlas, C.I. 4118, carrying the Rh2 resistance gene, and a Bavarian 2-rowed malting barley cv Steffi, susceptible for R. secalis. The assessment of resistance versus susceptibility was based on artificial infections with a one-spore inoculum in greenhouse tests and with pathotype mixtures in field tests. By testing a pathotype mixture of German origin good resistance was found for the Rh2 gene in the field.
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  • 3
    ISSN: 1432-2242
    Keywords: Solanum acaule ; Lycopersicon esculentum var. cerasiforme ; Satellite-DNA ; Species-specific ; Somatic hybrids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Species-specific highly repeated DNA sequences can be used to screen the progeny of protoplast fusions combining different species. Such probes are easy to clone and can be detected by fast methods, e.g., hybridization to total genomic DNA. Furthermore, due to their high copy number, hybridization signals are strong and represent more than one locus, unlike isozymes or resistance markers. After cloning and screening for species-specific DNA sequences we characterized the highly repeated DNA sequences of the solanaceous species Solanum acaule and Lycopersicon esculentum var. “gilva”. DNA sequencing and hy ridization revealed a prominent, tandemly arranged satellite DNA repeat of 162 bp in Lycopersicon esculentum and a different satellite repeat of 183 bp, also tandemly organized, in Solanum acaule. Each repeat is absent in the respective other species. Therefore, we have used these DNA repeats as markers to distinguish regenerated interspecific somatic hybrids from the respective fusion partners. These hybrids were clearly identified by Southern hybridization and dot-blot assays to the respective 32P-labelled satellite DNA.
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  • 4
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0022-2852
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0045-6039
    Keywords: back-transplantation experiments ; commitment of sensory and autonomic precursor cells in PNS ganglia and ; dorsal root ganglia ; quail-chick chimaeras
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Planta 7 (1929), S. 118-123 
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 3 (1969), S. 390-400 
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the fall and in early spring P. scaber and O. asellus released gaseous ammonia in the form of more or less regularly spaced bursts. In the spring about twice as much ammonia was released by O. asellus than in the fall. In late spring and summer, however, both species released ammonia in a rhythmic fashion, with a maximum at noon and early in the afternoon, and a minimum early at night. Sometimes a second maximum occurred late at night. In O. asellus the addition of a moist substrate to the reaction chamber shifted the maximum of the release of ammonia from noon to late night and early morning. Fed specimens of P. scaber released only about one-third as much NH3 as fasting animals and—at least in constant darkness—with a period of much reduced amplitude. It is concluded that the rhythmical release of ammonia is inversely related to the pattern of locomotory activity of these animals. This would implicate mechanisms that regulate either the production or the release of ammonia in such a way that the maximum occurs at a time when the animals' production of energy is at a minimum and when they are protected against loss of water by sitting in their moist retreats.
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  • 9
    ISSN: 1435-2451
    Keywords: Ankle Joint ; Morphometry ; Split-Line Pattern ; Posttraumatic Arthrosis ; Articular Cartilage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 26 menschliche Talusrollen wurden morphometrisch und funktionell analysiert, wobei das vorhandene Material in ein juveniles, ein adultes und ein seniles Kollektiv aufgeteilt wurde. Dabei ergaben sich folgende Beobachtungen: 1. Die einzelnen Knorpelabschnitte der Talusrolle weisen, mit Ausnahme des Cytoplasmaanteils in der tiefen Gelenkknorpelschicht erheblich altersbedingte Veränderungen auf. 2. Die Anzahl der Chondroeyten/Flächeneinheit ist beim juvenilen Kollektiv generell doppelt so groß wie beim adulten und senilen. 3. Der Cytoplasmaanteil der Chondrocyten/Flächeneinheit im oberflächlichen Knorpelgewebe ist beim juvenilen Kollektiv im dorsalen und ventralen Bereich der Talusrolle am größten, beim adulten Kollektiv hingegen im dorsomedialen und beim senilen im dorsalen Bereich. Die tiefen Gelenkknorpelschichten weisen weder bezüglich Alter, noch bezüglich Lokalisation, unterschiedliche Cytoplasmaanteile auf. 4. Die Einzelzellfläche der Knorpelzelle ist beim juvenilen Kollektiv in der oberflächlichen Knorpelschicht aller Gelenkbereiche halb so groß, wie beim adulten. 5. Der Gelenkknorpel der Talusrolle ist beim juvenilen Kollektiv im dorsalen, beim adulten und senilen in den medialen und lateralen Gelenkbezirken am dicksten. 6. Im Spaltlinienmuster der Talusoberfläche zeichnen sich im ventrolateralen und im ventromedialen Gelenkbezirk Druckmaxima ab. Im Bereich der Führungsrinne liegt ventral ein Druckminimum, dorsal hingegen ein Druckmaximum. Diesen Befunden zufolge scheint mit dem 30. Lebensjahr die morphologische Umgestaltung des Knorpelgewebes abgeschlossen zu sein. Die Zunahme der Zellgröße im dorsalen Gelenkbezirk der Talusrolle wird auf eine vermehrte funktionelle Beanspruchung zurückgeführt, was durch das Druckmaximum in diesem Bereich bestätigt wird. Die Zellzahl und die Knorpeldicke verhalten sich umgekehrt proportional.
    Notes: Summary Cartilage tissue from four different areas of the articular surface of the talar trochlea was analysed by light microscopic morphometry in the case of a juvenile collective (7 years of age), an adult one (30 years of age) and a senile one (80 years of age). The following observations were impressive: 1. With the exception of the cytoplasm fraction in the deep layer of the articular cartilage, the cartilage of the talar trochlea shows considerable changes due to age. 2. The juvenile collective shows double the number of chondrocytes per unit area as compared with the adult and the senile collectives. 3. In the case of the juvenile collective, the cytoplasm fraction of chondrocytes per unit area in the superficial layer of the articular cartilage reaches the highest values in the dorsal and ventral areas of the talar trochlea. The adult collective, however, shows maximum values in the dorsomedial area and the senile collective in the dorsal area. The deep layers of the articular cartilage do not show different cytoplasm fractions with regard to age or localisation. 4. The cellular single area of the juvenile cartilage in the superficial layer of all articular areas is half as large as that of the adult cartilage. 5. In the case of the juvenile collective, the thickness of the articular cartilage of the talar trochlea reaches maximum values in the dorsal area; in the case of the adult and senile collectives, in the medial and lateral areas. 6. In the split-line pattern of the trochlear surface compressive strain is evident in the ventrolateral and ventromedial articular areas. In the ventral area of the trough-line guide minimum pressure is observed; however, in the dorsal area there is maximum pressure. According to these findings the morphological transformation of the cartilage tissue seems to have come to an end as soon as the 30th year of life is reached. The increase of the cell size in the dorsal articular area of the talar trochlea is attributed to the intensified functional strain. This assumption is confirmed by maximum pressure in this area.
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  • 10
    Publication Date: 2018-03-06
    Description: Plants and fungi display a broad range of interactions in natural and agricultural ecosystems ranging from symbiosis to parasitism. These ecological interactions result in coevolution between genes belonging to different partners. A well-understood example is secreted fungal effector proteins and their host targets, which play an important role in pathogenic interactions. Biotrophic smut fungi (Basidiomycota) are well-suited to investigate the evolution of plant pathogens, because several reference genomes and genetic tools are available for these species. Here, we used the genomes of Sporisorium reilianum f. sp. zeae and S. reilianum f. sp. reilianum , two closely related formae speciales infecting maize and sorghum, respectively, together with the genomes of Ustilago hordei , Ustilago maydis , and Sporisorium scitamineum to identify and characterize genes displaying signatures of positive selection. We identified 154 gene families having undergone positive selection during species divergence in at least one lineage, among which 77% were identified in the two investigated formae speciales of S. reilianum . Remarkably, only 29% of positively selected genes encode predicted secreted proteins. We assessed the contribution to virulence of nine of these candidate effector genes in S. reilianum f. sp. zeae by deleting individual genes, including a homologue of the effector gene pit2 previously characterized in U. maydis . Only the pit2 deletion mutant was found to be strongly reduced in virulence. Additional experiments are required to understand the molecular mechanisms underlying the selection forces acting on the other candidate effector genes, as well as the large fraction of positively selected genes encoding predicted cytoplasmic proteins.
    Electronic ISSN: 1759-6653
    Topics: Biology
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