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  • 1
    Electronic Resource
    Electronic Resource
    The third fundamental form metric for hypersurfaces in nonflat space forms (1999)
    Springer
    Journal of geometry 65 (1999), S. 130-142 
    Details
    ISSN: 1420-8997
    Keywords: 53 B 25 ; 53 C 42 ; 53 C 25 ; third fundamental form metric ; hypersurfaces in nonflat space forms ; Einstein metric ; Codazzi tensor ; isoparametric hypersurfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract For hypersurfaces with regular Weingarten operator in nonflat space forms we study the relations between the intrinsic geometry of the third fundamental form metric and the extrinsic geometry of the hypersurface. We prove a theorema-egregium-type result for this metric and, in particular, give a local classification of hypersurfaces in case of an Einstein structure of this metric.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01228684
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  • 2
    Electronic Resource
    Electronic Resource
    Production and cytogenetics of intergeneric hybrids between Brassica napus and Orychophragmus violaceus (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 131-136 
    Details
    ISSN: 1432-2242
    Keywords: Brassica napus, Orychophragmus violaceus ; Intergeneric hybrid ; Somatic separation of genome ; Mixoploid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The intergeneric hybrid between Brassica napus and Orychophragmus violaceus was obtained by means of embryo culture technique with the latter as the pollen parent. The hybrid was morphologically intermediate between its parents, but could produce a lot of seeds when selfed. Somatic separation of the genomes from the two parental species was observed during the mitotic divisions of some of the hybrid cells. Thus, the hybrid became the mixoploid in nature, consisting of haploid and diploid cells of B. napus, and a nuclear — cytoplasmic hybrid, with the cytoplasm of B. napus and the nuclei of O. violaceus, and the hybrid cells. Pollen mother cells with 19, 12 and 6 bivalents, respectively, were produced by the hybrid. From the selfed progeny of the hybrid, mainly two kinds of plants, B. napus and the hybrid, were found. The hybrid plants of the selfed progeny again produced two kinds of plants, B. napus and the hybrid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220869
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Production and cytogenetics of the intergeneric hybrids Brassica juncea×Orychophragmus violaceus and B. carinata×O. violaceus (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 251-265 
    Details
    ISSN: 1432-2242
    Keywords: Key words Brassica juncea ; Brassica carinata ; Orychophragmus violaceus ; Intergeneric hybrids ; Genome separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Intergeneric hybrids between Brassica juncea (2n=36), B. carinata (2n=34) and Orychophragmus violaceus (2n=24) were produced when B. juncea and B. carinata cultivars were used as female parents. The hybrids between B. juncea and O. violaceus had an intermediate morphology except for petal colour and were partially fertile. The hybrids between B. carinata and O. violaceus had a matroclinous morphology and were nearly fertile. Cytological analysis of the hybrids and their progenies gave the following results. (1) In the hybrids between B. juncea and O. violaceus, the somatic tissues of the roots, leaves and styles were mixoploid (2n=12–42), and cells with 24, 30 or 36 chromosomes were the most frequent. Based on the recorded numbers and behaviour of the mitotic and meiotic chromosomes, complete and partial separation of the parental genomes was proposed to have occurred during mitosis. This resulted in the occurrence of cells with possibly complete and incomplete complements of the parental species and cells with parental complements and some additional chromosomes from the other parent. (2)  Pollen mother cells (PMCs) possibly with both parental chromosome complements, only B. juncea chromosomes or a complete B. juncea complement with additional O. violaceus chromosomes were more competitive in entering meiosis. The majority of fertile gametes were deduced to have been produced by PMCs with a B. juncea complement with or without additional O. violaceus chromosomes. (3) The progeny plants from selfed hybrids between B. juncea and O. violaceus were morphologically either of a B. juncea, hybrid or variable type. Cytologically they were grouped into six types according to the frequencies of cells with various chromosome numbers. All of the plants except 2 which constituted two types, were mixoploids, composed of cells with various chromosome numbers, mainly in a certain serial range. (4) The hybrid plants between B. carinata and O. violaceus were mixoploids with chromosome numbers in the range of 12–34, and cells with 2n=34 were the most frequent. The main categories of PMCs with 17 bivalents at metaphase I and 17 : 17 segregations at anaphase I contributed to the high fertility of the hybrids and the fact that their progeny after selfing were mainly plants with 2n=34. Somatic and meiotic separation of the parental genomes was proposed to have occurred in the hybrids between B. carinata and O. violaceus. (5) Mitotic and meiotic elimination of what could be O. violaceus chromosomes might also have contributed to the observed mitotic and meiotic cell types in the two kinds of hybrids studied. Finally, the possible mechanisms behind these cytological observations and their potential in the production of Brassica aneuploids were discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050734
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    Paper (German National Licenses)
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