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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 22 (1989), S. 3388-3394 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 19 (2000), S. 224-228 
    ISSN: 1432-203X
    Keywords: Key words Pinus aristata ; P. griffithii ; P. monticola ; Pollen tubes ; Transformation ; Particle bombardment ; In vitro fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A biolistic particle delivery system was used to genetically transform pollen tubes of three species of white pine (Pinus aristata, P. griffithii and P. monticola). The introduced plasmid DNA contained the GUS coding sequence flanked by the 35S CaMV promoter and NOS terminator sequences. Successful gene delivery was demonstrated by transient GUS expression as evaluated by standard histochemical assay. Distance of target specimens significantly influenced transient GUS expression in all three species of white pine. A target distance of 6 cm resulted in a significant number of transformed pollen tubes in P. aristata and P. griffithii, while distances of 6 and 9 cm resulted in a significant number of transformed pollen tubes in P. monticola. Generally, the number of pollen tubes expressing GUS activity was higher in P. aristata than in P. griffithii and P. monticola. The possibility of using GUS-transformed pollen tubes in conjunction with in vitro fertilization in conifers was examined. Gene expression in pollen tubes was also examined under electron microscopy where the X-glu reaction product occurred as large crystalline electron-dense precipitates in the cytoplasm.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2145
    Keywords: Key words Conifer ; Female gametophyte ; In vitro fertilization ; Pollen tube penetration ; Pseudotsugamenziesii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Pollen tube and female gametophyte interactions in Douglas fir (Pseudotsuga menziesii) were examined in vitro. Formation of pollen tubes in Douglas fir occurred on a modified Murashige and Skoog medium in which concentrations of H3BO3 and Ca(NO3)2 were altered and supplemented with sucrose and polyethylene glycol. Addition of 100 μg/ml H3BO3 and 300 μg/ml Ca(NO3)2 resulted in optimum pollen viability. Lack of H3BO3 inhibited pollen tube formation. Addition of H3BO3 and Ca(NO3)2 significantly increased pollen tube formation within one week in culture. Using a medium supplemented with mannitol, viability of Douglas fir pollen can be sustained for 7 weeks in culture, about the same length of time as in vivo. However, pollen tubes are not formed. This suggests that the factors responsible for tube formation reside in the external environment of the pollen. Culture of female gametophytes to examine egg viability and longevity had not been done previously. We found that egg viability in culture is short-lived, and therefore the window to study and manipulate events of fertilization in Douglas fir is very limited. In spite of this, about 7% of the female gametophytes that were co-cultured became penetrated by pollen tubes. In vitro archegonial penetration has been repeatedly achieved, but pollen tubes also penetrated other parts of the female gametophytes. Pollen tubes also penetrated non-viable eggs. Most female gametophytes were not penetrated because of pollen tube branching and swelling, failure of tubes to orient towards the female gametophytes, or premature pollen tube death due to plasmolysis. This report outlines the first attempt towards in vitro fertilization in conifers.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 13 (2000), S. 75-84 
    ISSN: 1432-2145
    Keywords: Key words White pine ; Egg ; Sperm ; Fertilisation ; Cytoplasmic inheritance ; Proembryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Fertilisation and proembryo development are described from transmission electron micrographs emphasising the origin and fate of the maternal and paternal mitochondria and plastids. During central cell and egg development mitochondria migrate toward the nuclei, forming a perinuclear zone consisting predominantly of maternal mitochondria and polysomes. At the same time, maternal plastids transformed and at fertilisation are excluded from the neocytoplasm. The pollen tube releases two sperm nuclei into the egg with cytoplasm from the generative cell and the tube cell. The leading sperm nucleus fuses with the egg nucleus and a small number of paternal mitochondria and plastids are taken into the perinuclear zone. The second sperm nucleus degenerates. As the zygote nucleus undergoes mitosis followed by free nuclear division and nuclear migration to the chalazal end of the archegonium, maternal and paternal organelles intermingle within the neocytoplasm. The result is paternal inheritance of plastids and biparental, but predominantly maternal, inheritance of mitochondria. This pattern is consistent within the Pinaceae but differs from some other conifer families.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 96 (1998), S. 1057-1063 
    ISSN: 1432-2242
    Keywords: Key words Conifer ; Female gametophyte ; In vitro fertilization ; Pollen tube ; Pseudotsuga menziesii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Our previous attempt on in vitro fertilization (IVF) in conifers resulted in pollen tube penetration of female gametophytes, but because of the rapid decline in egg viability, no further interaction occurred. In this report, we describe for the first time that IVF has been achieved in conifers. Using Douglas fir (Pseudotsuga menziesii), we describe a two-step process which involved induction of pollen tubes in culture followed by introduction of isolated female gametophytes at the tips of growing pollen tubes. Pollen tubes penetrated the introduced isolated female gametophytes at various places, but a number of tubes entered the egg cell through the neck cells similar to the in vivo condition. Under our current culture conditions, longevity of pollen tubes and eggs has been improved resulting in the release of sperms, fusion of gametes, and initial formation of the proembryo. Continued plasmolysis of the egg limited the number of successful gametic interactions. IVF has been accomplished in flowering plants in several ways, but the gametophyte-gametophyte IVF system described in this paper is unique. IVF offers a novel breeding technology that takes advantage of the sexual reproductive route. When coupled with hybridization and genetic transformation, IVF could result in the development of stable novel genotypes of economically superior trees.
    Type of Medium: Electronic Resource
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