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  • 1
    Publication Date: 2014-12-24
    Description: Angiosperm reproduction is characterized by alternate diploid sporophytic and haploid gametophytic generations. Gametogenesis shares similarities with that of animals except for the formation of the gametophyte, whereby haploid cells undergo several rounds of postmeiotic mitosis to form gametes and the accessory cells required for successful reproduction. The mechanisms regulating gametophyte...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Plant Science 97 (1994), S. 61-67 
    ISSN: 0168-9452
    Keywords: Endogenous β-glucuronidase activity ; Methanol ; Nicotiana tabacum ; Plant gene expression ; Transgenic plants ; gus A gene
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 71 (1985), S. 325-329 
    ISSN: 1432-2242
    Keywords: A. tumefaciens ; A. rhizogenes ; Brassica napus ; Plant development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The response of oilseed rape cultivars to infection with Agrobacterium tumefaciens and A. rhizogenes and the possibility of regenerating genetically transformed oilseed rape plants were examined. The frequency at which Agrobacterium induced galls or hairy-roots on in vitro cultured plants ranged from 10% to 70%, depending on the cultivar. From galls induced by the tumorigenic strain T37, known to be strongly shoot inducing on tobacco, roots developed frequently. Occasionally, shoots formed and some of these produced tumour cell specific nopaline. Attempts to grow the transformed shoots into plants have so far been unsuccessful. Whole plants transformed with Ri-T-DNA, however, were regenerated. These had crinkled leaves and abundant, frequently branching roots that showed reduced geotropism, similar to previously isolated Ri T-DNA transformed tobacco and potato plants. The transformed oilseed rape plants flowered, but failed to form seeds.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 70 (1985), S. 440-446 
    ISSN: 1432-2242
    Keywords: Agrobacterium rhizogenes ; Potato ; Somaclonal variation ; Genetic manipulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Forty-two potato plants were regenerated from a hairy-root line obtained after infection of a shoot of Solanum tuberosum cv ‘Desiree’ with Agrobacterium rhizogenes strain LBA 9402 (pRil855). Transformed plants were uniform and had a distinct phenotype and development compared with untransformed controls. Their growth was vigorous, especially early in their development, their roots were abundant and showed reduced geotropism, their leaves were slightly crinkled and glossy and they produced longer tubers with more frequent, prominent eyes. Cytological examination showed that ten of the forty-two transformed plants had either 47 or 49 chromosomes instead of the normal 48. In two of these aneuploids structural changes were observed.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2145
    Keywords: Key words LIM cDNAs ; Pollen-specific ; Zinc finger ; Nicotiana tabacum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A PCR-generated DNA probe covering the region corresponding to the two contiguous LIM domain sequences from the sunflower PLIM-1 cDNA was used to screen a cDNA library prepared from poly-A+ RNA isolated from mature Nicotiana tabacum pollen. Two clones were isolated and found to have unique but closely related nucleotide sequences NTPLIM1a and NTPLIM1b. Homology searches revealed the presence of two LIM domain repeats in each clone. Detailed spatial and temporal northern blot analysis showed that the NTPLIM transcripts were present specifically in mature and germinating pollen and were detectable immediately before the asymmetrical division pollen mitosis I, reaching a maximal level in mature pollen. Southern blot analysis revealed the NTPLIM1a and NTPLIM1b genes to be single-copy and members of a small gene family in the N. tabacum genome. Analysis of a genomic clone encoding NTPLIM1a revealed that the gene is split by four introns ranging from 79 to 922 bp in length. The high levels of developmentally regulated expression specifically in pollen suggests an important role for these proteins in pollen maturation and/or function.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2145
    Keywords: Key words NTP303 glycoprotein ; Pollen-specific Ntp303 gene ; Pollen-tube specific protein ; Plant reproduction ; Biochemical analysis ; Pollen development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The pollen-specific gene Ntp303 belongs to the class of late pollen specific genes. It is first transcribed directly after pollen mitosis. Biochemical properties, appearance and precise location of the NTP303 protein during pollen development and pollen tube growth were studied by amino-acid micro-sequencing, protein gel blotting and immuno-localization. Antisera were raised against recombinant proteins, encoded by sequences of the pollen-specific Ntp303 gene. The antibodies specifically recognized a 69-kDa glycoprotein. Electron-microscopic immuno-localization of the protein revealed the presence of high concentrations of the NTP303 protein at the vegetative plasma membranes that surround the vegetative cell, the generative cell and the sperm cells of pollen and pollen tubes. The generative plasma membranes of the generative cell and the sperm cells were negative. NTP303 protein was also present in the cell walls and in callose plugs. With this method it was shown that the NTP303 protein was already present in mid-bicellular pollen, after the first, asymmetrical pollen mitosis. Possible functions for the NTP303 protein are discussed in relation to its properties and its association with the vegetative plasma membranes.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5028
    Keywords: CaMV 35S ; Nicotiana tabacum ; pollen ; reporter genes ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The tomato lat52 gene encodes an essential cysteine-rich protein preferentially transcribed in the vegetative cell during pollen maturation. Detailed analyses of the identity, organization and role of cis-regulatory elements in controlling the precise developmental and tissue-specific expression of lat52 during pollen development were performed. Analysis of a series of 5′ promoter deletion mutants stably introduced into tobacco demonstrated differential developmental activation of deletion mutants during pollen development. All major cis-regulatory elements required for pollen-specific transcription were located within the upstream region −492 to −52. This region was shown to comprise three independent activator domains A, B and C, each sufficient to activate the minimal CaMV 35S promoter in a pollen-specific manner. 5′ deletion and gain of function approaches were used to show that domain A and the previously defined motif PBII (sub-domain B1) were largely redundant in the presence of downstream sequences in mature pollen. Within domain B two novel pollen-specific sub-domains B2 and B3 were identified. Within domain C, the activity of the PBI motif (sub-domain C1) was shown to be strictly dependent upon a downstream 20 bp pollen-specific activator unit −72 to −52 (sub-domain C2), containing two novel co-dependent regulatory elements AGAAA and TCCACCATA. These results demonstrate that transcriptional activation of lat52 is controlled by a complex of pollen-specific cis-regulatory elements which cooperate to achieve maximum levels of gene expression throughout pollen maturation. Alternative models of the interaction of identified cis-regulatory elements with putative trans-acting factors within the lat52 promoter and their developmental utilization are presented.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-5028
    Keywords: Agrobacterium tumefaciens ; gene expression ; potato ; T-DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In potato line Mb1501B one or possibly two normal size Ti TL-DNA copies per tetraploid genome were detected by Southern blot analysis, but no TR-DNA. The TL-DNA probably contained the entire transposon Tn1831 inserted at the T-DNA auxin gene for transcript 2. Northern blot analyses of the steady-state RNA in different Mb1501B tissues isolated from (i) shoots cultured in vitro (ii) grafted plants and (iii) tubers, showed that that TL-DNA transcripts 3, 4, 6a and 7 were expressed most abundantly in the cultured shoots. They formed approximately 0.0023 to 0.0007% of the total poly(A) RNA. Transcripts 1, 5 and 6b were not detected in any of the tissues analysed. This indicated even lower levels of expression (below approximately 0.0001% of the total poly(A) RNA or, making certain assumptions, an abundance of less than one T-DNA derived RNA molecule per cell). As expected, transcript 2 was not detected in any of the Mb1501B tissues. The abundance of the transcripts was reduced in grafted plants and tubers compared with cultured shoots with the greatest decrease (5×) for transcripts 4, 6a and 7. Transcript 4, the one most responsible for the changed growth and development of Mb 1501 B, formed approximately 0.0003% of the poly(A) RNA from both grafted plants and tubers.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 187 (1995), S. 144-154 
    ISSN: 1615-6102
    Keywords: Pollen ; Genetic ablation ; Diphtheria toxin ; Nicotiana tabacum ; Cell migration ; Pollen-specific gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The technique of genetic cell ablation involves the targeted expression of a cell autonomous cytotoxic protein under the control of cell-specific regulatory sequences. This technique allows the investigation of cell-cell interactions by inducing selective death in a precisely controlled and cell autonomous manner. Here, targeted vegetative cell-specific ablation was used to examine the role of the vegetative cell (VC) in controlling generative cell (GC) behaviour and differentiation during pollen development. The tomatolat 52 late-pollen promoter, which has been shown to be activated specifically in the nascent VC immediately following pollen mitosis I (PMI), was used to direct expression of the cytotoxic diphtheria toxin A chain (DTA) in both transient expression assays using microprojectile bombardment and in transgenic tobacco plants. Transient expression of DTA linked to thelat 52 promoter (lot 52-DTA) in pollen dramatically reduced the expression of a co-transfected reporter gene fusion, demonstrating the cytotoxicity of DTA to pollen. Genetic and phenotypic analysis oflat 52-DTA transformants demonstrated that DTA expression led to a pollen-lethal phenotype, recognisable as small acytoplasmic pollen grains at anthesis, which affected 50% of the pollen population in single locus transformants. Detailed cytological analysis using confocal laser scanning microscopy and vital staining using fluorescein diacetate (FDA), showed that the first sign of cell ablation during pollen development was a loss of vital staining of the VC immediately following PMI. In contrast, the GC retained viability for up to several days following VC ablation, but progressively lost viability in the absence of a functional VC. Of particular interest was the observation that in the absence of VC function the generative cell (GC) failed to undergo normal migration away from the pollen grain wall into the VC cytoplasm. These results directly demonstrate the dependence of the GC on VC cell functions and highlight the importance of VC-GC interactions in controlling GC migration.
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