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  • 1
    Electronic Resource
    Electronic Resource
    The Economic Viability of Frequency Reward Programs in a Strategic Competitive Environment (2003)
    Berkeley, Calif. : Berkeley Electronic Press (now: De Gruyter)
    Review of marketing science 1.2003, 1, art1 
    Details
    ISSN: 1546-5616
    Source: Berkeley Electronic Press Academic Journals
    Topics: Economics
    Notes: We examine the conditions that enhance the economic viability of frequency reward programs in a strategic competitive environment. We focus particularly on conditions related to consumer behavior, namely the extent to which consumers value the future benefits offered by the reward, the expandability of the category, and consumers' preferences for competing brands. Consumers maximize utility over a long-term time horizon, taking into account the value of the reward. Two firms maximize profits over a long-term time horizon. They first decide between implementing a frequency reward program or a traditional pricing policy (a constant price), and then decide on the specific prices. We numerically solve for the sub-game perfect equilibrium for this two-stage game. We find that a brand is more likely to find reward programs to be viable strategies if consumers value future benefits, if reward programs can expand the market, and if the brand has a higher preference. The market expandability finding is particularly interesting. If the sales increases generated by reward programs represent category growth, the power of frequency reward programs makes them an effective vehicle for generating profits. However, if gains come mainly from competitors, the power of frequency reward programs precipitates a strong competitive response that erodes profits in a classic prisoner's dilemma. We use the airline industry to explore our market expandability finding. We find evidence that the "major" airlines introduced reward programs to counter-act a stronger outside category (new entrants), and in doing so, they expanded their market.
    Type of Medium: Electronic Resource
    URL: http://www.bepress.com/romsjournal/vol1/iss1/art1
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  • 2
    Electronic Resource
    Electronic Resource
    Activation of Natural Killer-Like YT-INDY Cells by Oligodeoxynucleotides and Binding by Homologous Pattern Recognition Proteins (2005)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Scandinavian journal of immunology 62 (2005), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The present study was designed to examine the binding and signalling effects of single base and CpG dinucleotide phosphodiester (Po) oligodeoxynucleotides (ODN) on the human natural killer (NK)-like cell line (YT-INDY). Single base Po ODN composed of 20-mers of guanosine (dG20), adenosine (dA20), cytosine (dC20) or thymidine (dT20) as well as ‘conventional’ Po CpG ODN were examined for their ability to bind and activate YT-INDY cells. Binding by dG20 and CpG ODN to YT-INDY cells was saturable and specific. dG20 binding was competitively inhibited by homologous dG20 and heterologous CpG ODN but not by dC20 and dA20. Two different YT-INDY membrane proteins (18 and 29 kDa) were identified by ligand (Southwestern) blotting with biotinylated dG20 and CpG. The specificity of the ODN-binding protein(s) was further confirmed by ODN depletion experiments using a teleost recombinant protein orthologue [nonspecific cytotoxic cells (NCC) cationic antimicrobial protein-1 (ncamp-1)] known to bind CpG and dG20. Cell proliferation and activation studies showed that dG20 and CpG treatment of YT-INDY cells induced cellular DNA synthesis (i.e. G1 to S-phase conversion). This signalling function was accompanied in dG20-treated cells by proliferation 10 h posttreatment. Both dG20 and CpG ODN binding induced a calcium flux in YT-INDY cells within seconds of treatment. These experiments demonstrated that Po single base dG20 and CpG ODN bind to a (potential) new class of cell-surface proteins that mediate the activation of YT-INDY cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.2005.01665.x
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  • 3
    Electronic Resource
    Electronic Resource
    Role of purine metabolism in thidiazuron-induced somatic embryogenesis of geranium (Pelargonium×hortorum) hypocotyl cultures (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 98 (1996), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Somatic embryogenesis in geranium (Pelargonium×hortorum Bailey cv. Scarlet Orbit Improved) was achieved by culturing hypocotyl sections on Murashige and Skoog (1962) (MS) medium containing 10 μM thidiazuron (TDZ) (induction medium) for 3 days and subsequently transferring the sections onto a basal medium lacking any plant growth regulators (expression medium). Addition of the purine analogue 2.6-diaminopurine (DAP) to the somatic embryo induction medium completely inhibited the embryogenic response as well as chlorophyll accumulation without affecting enlargement of the treated tissues. Addition of 20 μM adenine sulphate to the expression medium, i.e during embryo growth and development phase, completely reversed the DAP-induced inhibition of the embryogenic response while addition during the induction phase caused only a 50% reversal of the inhibition. Analysis of endogenous levels of plant growth substances indicated that TDZ alone elevated the levels of auxins, cy-tokinins and abscisic acid while the presence of DAP during the induction phase caused a further increase in the levels of adenine and adenosine. These findings indicate a possible critical role for purines in embryogenesis from geranium hypocotyl tissues. However, the conversion of cytokinin bases to their corresponding nucleotide forms was not evident as the levels of isopentenyl adenine and zeatin increased during the second day of culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1996.tb05706.x
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  • 4
    Electronic Resource
    Electronic Resource
    Thidiazuron-induced morphogenesis of Regal geranium (Pelargonium domesticum): A potential stress response (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 101 (1997), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Thidiazuron (TDZ), a phenylurea derivative with cytokinin-like activity, induced the development of outgrowths on root tissue of vegetatively propagated geraniums (Pelargonium × hortorum, Pelargonium domesticum and Pelargonium graveolens). Root outgrowths developed as globular or elongated structures following treatment with 10–30 μM TDZ and many of these structures differentiated to produce shoots. Analysis of root and shoot samples, collected daily during the outgrowth induction phase and at the end of the treatment period, revealed significant changes in accumulation of manganese, iron, copper, calcium, magnesium and potassium. The markers of a stress response, proline, abscisic acid and 4-aminobutyrate, accumulated in the TDZ-treated roots during the first week of induction. Assessment of the adenylate phosphate pool sizes of the TDZ-treated plants indicated a sequential increase in the endogenous levels of ATP, ADP and AMP following each application of TDZ. The energy charge ratio was also significantly higher in TDZ-treated plants indicating an increase in ATP utilizing systems. Similarily, pyridine nucleotide pool size analyses revealed that TDZ-treated plants had a higher level of endogenous NADP+ in the initial 24-h period following each treatment and the level of NADPH increased following the third application of TDZ. The ratio of NADPH/NADP+ was significantly higher in TDZ-treated plants throughout the treatment period. We hypothesize that the primary effect of TDZ was through induction of a stress response in the geranium plants. In order to overcome this stress, the plants accumulated significantly higher levels of proline, ABA and 4-aminobutyrate. Moreover, the plants also exhibited modified metabolic processes which in turn led to increased availability of energy and reducing power required for subsequent growth and to initiate stress adaptation mechanisms including modified cellular processes and regenerative outgrowth development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1997.tb01835.x
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  • 5
    Electronic Resource
    Electronic Resource
    Thidiazuron-induced somatic embryogenesis in intact seedlings of peanut (Arachis hypogaea): Endogenous growth regulator levels and significance of cotyledons (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 94 (1995), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The regulatory role of thidiazuron (TDZ) and explant factors in imparting somatic embryogenic potential was assessed in relation to endogenous growth regulator levels in peanut (Arachis hypogaea L. cv. Tango). TDZ induced somatic embryogenesis over a range of concentrations (0.5 to 10 μM). Culture of seedlings for just 2 days on TDZ-supplemented medium was sufficient to induce somatic embryogenesis. Seedling age and retention or removal of cotyledons during culture influenced morphogenic potential significantly. The younger the seedlings, the better was the embryogenic response to TDZ treatment. The embryogenic potential of seedlings was limited for explants with no cotyledons and they did not respond to increasing levels of TDZ. In contrast, retention of at least one or both the cotyledons resulted in increased response to TDZ. Endogenous levels of cytokinins, auxins and abscisic acid were influenced by TDZ treatment, while TDZ itself was detected only in the cotyledons. The cytokinin N6-(2-iso-pentenyl)adenine (2iP) fluctuated on a 10-day cycle in the cotyledons; TDZ treatment suppressed this change and caused an overall decrease in the pool of available 2iP in the tissue. It appeared that TDZ induced somatic embryogenesis in peanut by influencing endogenous levels of both auxin and cytokinins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1995.tb05311.x
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  • 6
    Electronic Resource
    Electronic Resource
    Plantlets from mesophyll protoplasts of Solanum xanthocarpum (1982)
    Springer
    Plant cell reports 1 (1982), S. 219-220 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Young leaves of Solanum xanthocarpum from axenic shoot cultures released viable protoplasts when treated with appropriate enzymes. The protoplasts on culture in modified Murashige and Skoog (1962) medium supplemented with 2,4-dichlorophenoxy-acetic acid (0.5 mg/l), naphtha leneacetic acid (1 mg/l), kinetin (1 mg/l) and organic nutrients of KM (Kao and Michayluk 1975) regenerated to form callus tissue as a result of repeated divisions. Protoplast-derived calli differentiated into shoots on MS medium enriched with kinetin (0.5 mg/l) and rooting could be initiated by transferring the shoot-buds to basal medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00270240
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  • 7
    Electronic Resource
    Electronic Resource
    Somatic embryogenesis and shoot regeneration from intact seedlings of Phaseolus acutifolius A., P. aureus (L.) Wilczek, P. coccineus L., and P. wrightii L. (1992)
    Springer
    Plant cell reports 11 (1992), S. 163-168 
    Details
    ISSN: 1432-203X
    Keywords: N6-benzylaminopurine ; Grain legumes ; Organogenesis ; Phaseolus ; Somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A rapid, one-step procedure has been developed for inducing direct organogenesis and somatic embryogenesis in cultures of Phaseolus coccineus L., P. acutifolius A., P. aureus L. [Vigna radiata L. Wilczek] and P. wrightii L. Development of somatic embryos and shoot buds occurred within 6–8 weeks of culture from intact seedlings raised on MS (Murashige and Skoog 1962) medium supplemented with N6-benzylaminopurine (BAP). Shoot buds or embryoids originated from subepidermal tissue of the regions adjacent to the shoot apex, hypocotyl and cotyledonary axils. While P. acutifolius and P. aureus were regenerated via shoot formation and P. wrightii by somatic embryogenesis, both embryogenesis and shoot regeneration were observed in P. coccineus. Relatively higher levels of BAP, 50–80 μM, were found to be optimal for inducing regeneration while lower concentrations were ineffective. About 40–70 shoots and 70–250 somatic embryos were produced per responding seedling. Regenerated shoots and somatic embryos developed into whole plants on a basal medium or the one supplemented with 1 μM naphthaleneacetic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232172
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  • 8
    Electronic Resource
    Electronic Resource
    Somatic embryogenesis and plant regeneration from zygotic embryo culture in blue spruce (Picea pungens Engelman.) (1992)
    Springer
    Plant cell reports 11 (1992), S. 299-303 
    Details
    ISSN: 1432-203X
    Keywords: Blue spruce ; Somatic embryogenesis ; Auxin and cytokinin ratio ; Abscisic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Somatic embryogenesis and plantlet formation have been achieved from cultured mature zygotic embryos of blue spruce (Picea pungens Engelman.). The effect of three basal media LP, LM, and BLG, all used at half-strength, was tested at the induction phase. LM medium induced somatic embryogenesis to a higher extent than LP whereas BLG did not produce any embryonal-suspensor mass representing stage 1 somatic embryos. The embryonal-suspensor mass was induced on a wide range of auxin/cytokinin ratios. However, media containing either 2 μM NAA and 10 μM BA, or 10 μM NAA and 5 μM BA produced somatic embryos that gave the highest frequency of plantlets. The level of ABA required in the maturation medium for somatic embryos to mature properly varied with the auxin/cytokinin levels in the induction medium on which the somatic embryos were derived. Inclusion of AgNO3 (10 – 100 μM) in the induction medium reduced somatic embryogenesis and embryo conversion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00235086
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  • 9
    Electronic Resource
    Electronic Resource
    Adventitious shoot induction and somatic embryogenesis with intact seedlings of several hybrid seed geranium (Pelargonium x hortorum Bailey) varieties (1992)
    Springer
    Plant cell reports 11 (1992), S. 443-448 
    Details
    ISSN: 1432-203X
    Keywords: Geranium ; Pelargonium ; Micropropagation ; Adventitious shoots ; Somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Intact seedlings of hybrid seed geranium (Pelargonium x hortorum Bailey) were tested for their ability to produce adventitious shoots and somatic embryos by direct culture of mature seeds on Murashige and Skoog (1962) medium (MS) supplemented with growth regulators BAP, BAP + IAA, or thidiazuron (TDZ). Ten varieties were tested in the presence of different BAP concentrations, four with BAP + IAA, and two with TDZ. Varieties used in this study differed in their response to BAP in the medium. Multiple adventitious shoots were produced by seven of the ten varieties tested. Multiple adventitious shoots were induced at all levels of TDZ in the medium. TDZ also induced callusing from roots and direct embryogenesis from intact hypocotyls. Adventitious shoots were separated, rooted and transferred to soil where they grew as normal healthy plants and flowered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232687
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  • 10
    Electronic Resource
    Electronic Resource
    Somatic embryogenesis in Nicotiana tabacum L.: induction by thidiazuron of direct embryo differentiation from cultured leaf discs (1993)
    Springer
    Plant cell reports 12 (1993), S. 154-159 
    Details
    ISSN: 1432-203X
    Keywords: Nicotiana tabacum ; somatic embryogenesis ; growth regulators ; thidiazuron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Induction of somatic embryogenesis by different growth regulators was examined in leaf disc cultures of Nicotiana tabacum L. Direct differentiation of somatic embryos occurred on media supplemented with naphthaleneacetic acid (NAA) and N6-benzylaminopurine (BAP). Thidiazuron (N-phenyl-N′-1, 2,3,-thiadiazol-5-ylurea; TDZ) not only substituted for the most effective NAA-BAP combination but also induced a higher frequency of somatic embryogenesis. Regenerated somatic embryos were capable of developing into plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239097
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