Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The suitability of different protocols was compared for entire plant regeneration by somatic embryogenesis, of the forage plants Lolium multiflorum Lam. (Italian ryegrass) and Festuca arundinacea Schreb. (tall fescue).In the first protocol, miniature embryos were used as starting material, while mature seeds were retained in the other two. Whichever the considered protocol, undifferentiated calli were produced on Murashige and Skoog MS medium supplemented with 2,4-D. The calli were subcultured in the dark on solid MS agar medium, containing 5 mg/1 2,4-D (protocol 2) or on solid MS medium followed by transfer to a rotated liquid MS medium with 2 mg/1 2,4-D (protocol 1). In these conditions, induction of somatic embryogenesis occurred, and whole plants were regenerated during a limited lapse of time, upon transfer in the light, to MS medium supplemented with BAP but devoid of 2,4-D. The simultaneous elimination of 2,4-D and transfer to light appeared essential for full regeneration of the plants. Using this characteristic, an additional step was added to a new protocol (protocol 3) in which microcalli, cultured on liquid MS medium containing 5 mg/1 2,4-D, were transferred to the same medium with 2 mg/1 2,4-D, in the dark. In these conditions, the suspensions kept their embryogenic potential for months.In all cases, plantlets were successfully transferred into the soil. An evaluation of the somaclonal variation potential of the plants issued from each protocol is now underway.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 111 (2001), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The cytoskeleton is involved in major developmental events in plant cell growth and differentiation. Nucleation events play a key role in the dynamic and organization of the microtubule (Mt) cytoskeleton. Among many proteins involved in Mt nucleation, γ-tubulin has been identified as an essential component of the Mt organizing centers (MTOC). In protoplasts, somatic embryogenesis induction has been correlated with remodeling of Mt cytoskeleton. We have investigated the specific developmental expression of γ-tubulin in Helianthus annuus. Two γ-tubulin isoforms have been detected by immunoblotting, with bands at 52 and 58 kDa. The larger γ-tubulin (58 kDa) is present in all the sunflower tissues tested and is associated with the nucleus. The smaller γ-tubulin (52 kDa), differing from the former at the carboxy-terminal end, is only present in meristematic and dedifferentiated cells and is not bound to the nucleus. This first demonstration of the presence of two γ-tubulins in plant cells is discussed in terms of distinct roles in the nucleation and organization of Mts.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Sunflower hypocotyl protoplasts (Helianthus annuus L. cv. Emil) divide symmetrically to form loosely associated microcolonies when cultured in liquid medium, whereas when embedded in agarose beads they divide asymmetrically to give rise to embryo-like structures. To understand the relationship between protoplast embedding and cell division patterns, we studied the deposition of β-linked glucan and the dynamics of microtubules during early phases of culture. After one day in culture, under both culture conditions, a small proportion of the protoplasts had already begun to rebuild a β-glucan cell wall and the process reached completion in all protoplasts after 10 days. Callose deposition was faster in agarose than in liquid medium but it concerned only 30–40% of the protoplasts and was not related to either division type. No marked differences were observed in cortical arrays of microtubules. However, in embedded protoplasts perinuclear microtubules formed a well-defined basket around the nucleus; these microtubules were never observed in liquid-cultured protoplasts. A narrow preprophase band was present only in dividing protoplasts cultured in liquid medium. The results suggest that asymmetric division could be related to the lack of a narrow preprophase band and that protoplast embedding enhances nucleation or stabilization of microtubules.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Munksgaard International Publishers
    Physiologia plantarum 122 (2004), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The organization of actin microfilaments was studied by immunofluorescence in protoplasts isolated from sunflower hypocotyls and cultured in an agarose matrix. Removal of the cell wall completely disrupted the actin cytoskeleton, which became progressively reorganized into cortical microfilament arrays and actin cables during protoplast culture. Treatment of protoplasts with arginine-glycine-aspartic acid (Arg-Gly-Asp) motif-containing peptides, to inhibit putative cell contacts with the agarose matrix, strongly affected this repair process: microfilament elongation and cable formation were inhibited and the connectivity between the cortical network and the perinuclear basket was lost. Furthermore, embryoid formation induced by agarose embedding was reduced. Similar effects were observed with a short treatment with latrunculin B, known to disrupt actin microfilaments. These results indicate that the actin network is involved in the signalling process that leads to polarity acquisition and embryoid determination in agarose-embedded protoplasts.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The genetic transformation of sunflower is very difficult. The protocols published so far combined wounding of meristematic axes by microprojectils or glass beads and gene transfer by Agrobacterium tumefaciens. The yields of transgenic plants were well below 0.1% in all cases. Treatment of meristematic explants of germinating seedlings by a pectinase, before wounding, followed immediately by Agrobacterium tumefaciens cocultivation, enhanced β-glucuronidase (GUS) gene expression in 14-day-old in vitro cultivated explants. Moreover, pectinase-treated explants showed a significant increase in interaction with bacteria compared to non-treated ones. This result suggests facilitated access of the bacteria to competent sunflower cells, due to cell-wall digestion by the pectinases. Furthermore, we show here, using competition experiments, that integrin-like proteins do not seem to be involved in the enhancement of bacterial binding to the cell explants.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The reactions leading to cinnamic acids from phenylalanine as only substrate were investigated in organelles from Quercus pedunculata Ehrh. roots.–“F 10 000′” fraction, including mitochondria and micro-bodies, catalyses the first reaction, i.e., cinnamate formation by deamination of phenylalanine.– Microsomal fraction catalyses all the steps from phenylalanine to caffeic acid via cinnamate and p-coumarate. These results suggest that microsomes are the intracellular site of the cinnamic units synthesis. The enzymes involved in these reactions, associated in the same cellular compartment, does not form a multienzyme system. The formation of caffeic acid by isolated microsomes is demonstrated for the first time; the reaction may be realised by an enzyme different from phenolase.– The free phenolic acids are the metabolically active forms.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sunflower hypocotyl protoplasts (Helianthus annuus L.) from 5 PIONEER genotypes (PT024, SMF3, EMIL, HA300*PT024, VK5F) and 1 public line (RHa 274) formed colonies at frequencies of up to 60% when plated in 0.25ml agarose beads in a modified L4 medium (Lenée and Chupeau 1986) containing 3mg/l NAA, 1mg/l BA and 0.1mg/l 2,4-D, and 1000mg/l casamino acids. Protoplast-derived colonies grew slowly into calli. Organogenesis was obtained from callus of PT024 on a MS medium containing NAA and BA at 1mg/l and GA at 0.1mg/l. Freshly excised shoots were induced to root by an IAA treatment. Regenerated plants were transferred to the greenhouse and seed was harvested within 7 months of the initial protoplast isolation.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In highly purified tonoplast fractions from Acer pseudoplatanus cells, the in vitro reversible phosphorylation of proteins affected only a restricted set of polypeptides. The phosphorylation process has been shown to be dramatically stimulated by calcium via the mediation of calmodulin as the transducer. The protein kinase(s) was totally inhibited by micromolar concentrations of a calmodulin antagonist. Tonoplast appears to be potentially a good experimental system for the evaluation of the effects of protein phosphorylation on membrane properties in plants.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1432-2048
    Keywords: Guaiacyl units ; Light effect ; Lignification ; Membrane permeability ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When fed with [14C] phenylalanine in the light, xylem tissues isolated from poplar stems were able to incorporate part of the radioactivity into both the guaiacyl and the syringyl residues of lignins. In the dark, only syringyl units were integrated into the polymer whereas the guaiacyl residues remained unlabeled. When a membrane perturber (isopropanol) was added to the incubation mixture, the label was incorporated into the guaiacyl units either in the light or in the dark. Conversely, a membrane stabilizer (CaCl2) prevented the labeling of the guaiacyl units even when the tissues were illuminated. These results suggest that light acts through the modification of membrane permeabilities, altering specifically the synthesis and the transport or the polymerization of guaiacyl-type units during the process of lignification.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ability to deliver free DNA into microspores of a highly androgenic hybrid of maize was assessed by electroporation, using a square wave pulse discharge apparatus. The electroporation medium was chosen according to its ability to maintain a high level of regeneration. Nuclease activities were analyzed and were inhibited by the addition of 100 mM KNO3 and MgSO4 in the electroporation medium. Seven expression vectors withUid A as the reporter gene under the control of cauliflower mosaic virus 35S, Lat 52-7, Zmg 13, Emu, Ubiq-1, Al, or Actl promoters were tested in relation to the level of ß-glucuronidase expression in maize microspores. The highest level of expression was obtained when theUid A gene was driven by the Actl promoter. Therefore, this vector was further used to define optimal conditions leading to highest levels of ß-glucuronidase expression. The parameters determined in this study could provide an ideal starting point for the obtention of transgenic maize plants from electroporated microspores.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...