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  • Key wordsSchizosaccharomyces pombe  (2)
  • Somatic embryogenesis  (2)
  • 1
    ISSN: 1432-203X
    Keywords: Key words Agrobacterium tumefaciens ; Benzylisoquinoline alkaloids ; California poppy ; Eschscholzia californica Cham. ; Genetic transformation ; Somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  An efficient Agrobacterium-mediated protocol for the stable genetic transformation of Eschscholzia californica Cham. (California poppy) via somatic embryogenesis is reported. Excised cotyledons were co-cultivated with A. tumefaciens strain GV3101 carrying the pBI121 binary vector. Except for the co-cultivation medium, all formulations included 50 mg l−1 paromomycin as the selective agent and 200 mg l−1 timentin to eliminate the Agrobacterium. Four to five weeks after infection, paromomycin-resistant calli grew on 80% of explants in the presence of 2.0 mg l−1 1-naphthaleneacetic acid (NAA) and 0.1 mg l−1 6-benzylaminopurine (BAP). Calli were cultured on somatic embryogenesis induction medium containing 1.0 mg l−1 NAA and 0.5 mg l−1 BAP, and somatic embryos were visible on 30% of the paromomycin-resistant calli within 3–4 weeks. Three to four weeks after the somatic embryos were transferred to phytohormone-free plant regeneration medium, 32% converted to paromomycin-resistant plants. Detection of the neomycin phosphotransferase gene and high levels of β-glucuronidase (GUS) mRNA and enzyme activity, and the cytohistochemical localization of GUS activity in all plant tissues confirmed the integrative transformation of the regenerated plants. The normal alkaloid profile of California poppy was unaffected by the transformation process; thus, the reported protocol could serve as a valuable tool to investigate the molecular and metabolic regulation of the benzophenanthridine alkaloid pathway.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 19 (2000), S. 421-426 
    ISSN: 1432-203X
    Keywords: Key words California poppy ; Eschscholzia californica ; Plant regeneration ; Somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The development of a rapid protocol for high-efficiency somatic embryogenesis and plant regeneration from seed-derived embryogenic callus cultures of California poppy (Eschscholzia californica Cham.) is reported. The optimized procedure required less than 13 weeks from the initiation of seed cultures to the recovery of plantlets and involved the sequential transfer of cultures onto solid Murashige and Skoog basal medium containing three different combinations of growth regulators. All steps were performed at 25  °C. Friable primary callus was induced from seeds of E. californica cultured on medium supplemented with 1.0 mg l−1 2,4-dichlorophenoxyacetic acid. The primary callus was transferred to medium containing 1.0 mg l−1 1-naphthaleneacetic acid and 0.5 mg l−1 6-benzylaminopurine to establish embryogenic callus and promote somatic embryogenesis. Regenerated plantlets were recovered after the conversion of somatic embryos on medium containing 0.05 mg l−1 6-benzylaminopurine and showed normal development. Embryogenic callus was induced at a frequency of 85%, an average of 45 somatic embryos were produced per callus, 90% of the somatic embryos converted, and about 70% of the plantlets were recovered in soil. The growth rate of somatic embryo-derived shoots could be increased by gibberellic acid treatment, but the resulting plantlets were hyperhydritic.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1617-4623
    Keywords: Key wordsSchizosaccharomyces pombe ; SNF2/SWI2 protein family ; ATPase/helicase domains ; DNA-binding domain ; Chromodomain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The SNF2/SWI2 ATPase/helicase family comprises proteins from a variety of species, which serve a number of functions, such as transcriptional regulation, maintenance of chromosome stability during mitosis, and various types of DNA repair. Several proteins with unknown functions are also included in this family. The number of genes that belong to this family is rapidly expanding, which makes it easier to analyze the common biological functions of the family members. This study was designed to clone the SNF2/SWI2 helicase-related genes from the fission yeast Schizosaccharomyces pombe in the hope that this would help to elucidate the common functions of the proteins in this family. The hrp1 + (helicase-related gene from S. p ombe) gene was initially cloned by PCR amplification using degenerate primers based on conserved SNF2 motifs within the ERCC6 gene, which encodes a protein involved in DNA excision repair. The hrp1 + ORF codes for an 1373-amino acid polypeptide with a molecular mass of 159 kDa. Like other SNF2/SWI2 family proteins, the deduced amino acid sequence of Hrp1 contains DNA-dependent ATPase/7 helicase domains, as well as a chromodomain and a DNA-binding domain. This configuration is similar to that of mCHD1 (mouse chromo-ATPase/helicase-DNA-binding protein 1), suggesting that Hrp1 is a S. pombe homolog of mCHD1, which is thought to function in altering the chromatin structure to facilitate gene expression. Northern blot analysis showed that the hrp1 + gene produces a 4.6-kb transcript, which reaches its maximal level just before the cells enter the exponential growth phase, and then decreases gradually. DNA-damaging agents, such as MMS, MNNG and UV, decrease the rate of transcription of hrp1 +. Deletion of the hrp1 + gene resulted in accelerated cell growth. On the other hand, overexpression of Hrp1 caused a reduction in growth rate. These results indicate that hrp1 + may act as a negative regulator of cellular growth.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1617-4623
    Keywords: Key wordsSchizosaccharomyces pombe ; DNA-damage inducibility ; Damage-responsive element ; Upstream activating sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Schizosaccharomyces pombe rhp51 + gene encodes a recombinational repair protein that shares significant sequence identities with the bacterial RecA and the Saccharomyces cerevisiae 1RAD51 protein. Levels of rhp51 + mRNA increase following several types of DNA damage or inhibition of DNA synthesis. An rhp51:: ura4 fusion gene was used to identify the cis-acting promoter elements involved in regulating rhp51 + expression in response to DNA damage. Two elements, designated DRE1 and DRE2 (for damage-responsive element), match a decamer consensus URS (upstream repressing sequence) found in the promoters of many other DNA repair and metabolism genes from S. cerevisiae. However, our results show that DRE1 and DRE2 each function as a UAS (upstream activating sequence) rather than a URS and are also required for DNA-damage inducibility of the gene. A 20-bp fragment located downstream of both DRE1 and DRE2 is responsible for URS function. The DRE1 and DRE2 elements cross-competed for binding to two proteins of 45 and 59 kDa. DNase I footprint analysis suggests that DRE1 and DRE2 bind to the same DNA-binding proteins. These results suggest that the DRE-binding proteins may play an important role in the DNA-damage inducibility of rhp51 + expression.
    Type of Medium: Electronic Resource
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