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  • 1
    Electronic Resource
    Electronic Resource
    The state of water in acclimating vegetative buds from Malus and Amelanchier and its relationship to winter hardiness (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 86 (1992), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The relationship between freezable water and cold hardiness during acclimation was studied using vegetative buds from several apple (Malus domestica Borkh) cultivars and from one saskatoonberry (Amelanchier alnifolia Nutt. cv. Smoky) cultivar. According to leakage data and visual assessments of cortical browning, vegetative buds of all cultivars were most tolerant to subfreezing temperatures in January. The hardy condition was also associated with maximum tolerance to desiccation. Qualitative features of freezing exotherms (number of peaks and temperature of the transition) were not correlated with the hardy condition in the tissues. However, the amount of unfrozen water, determined by quantifying the energy of the exotherms, increased with increasing hardiness. In buds that survived exposure to −45°C, freezing reduced the intracellular water content, but only to levels above the critical moisture content for desiccation damage. In buds that did not survive exposure to −45°C, freezing reduced the water content to levels equal to or less than the critical moisture content for desiccation damage. These observations suggest that the freezing of water in nonhardy tissue dried the tissue to moisture levels at which severe dehydration damage occurred. It appears that acclimation of vegetative apple buds involves at least two processes: (1) an increase in tolerance to dehydration and (2) an increase in the level of unfreezable water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1992.tb02162.x
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  • 2
    Electronic Resource
    Electronic Resource
    Vegetative growth and frost hardiness of cloudberry (Rubus chamaemorus) as affected by temperature and photoperiod (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 55 (1982), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of photoperiod and temperature on growth and induction and development of frost hardiness in cloudberry (Rubus chamaemorus L.) was examined in two experiments. The photoperiods were 8, 12 or 24 h and the temperatures were 18, 15, 12, 9, 4, 3, –3 or –4°C depending on the experiment. The level of hardiness was expressed as LT66 or LT50 (the lethal temperature for 66 or 50% of the plant material) for percentage of bud break and for the degree of coloring by triphenyltetrazolium chloride for rhizomes. The vegetative growth was clearly affected by daylength; petiole elongation, leaf growth, shoot dry weight and number of shoots per plant were all reduced under short days compared with long days. However, the photoperiod had no significant effect on hardening of buds or rhizomes. Hardening increased with successively decreasing temperatures. To get the maximum hardiness, plants had to be exposed to freezing temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1982.tb02267.x
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  • 3
    Electronic Resource
    Electronic Resource
    Seasonal development of cold stress resistance in several plant species at a coastal and a continental location in North Norway (1986)
    Springer
    Polar biology 5 (1986), S. 129-133 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Samples of 17 plant species (one herb, dwarf shrubs and trees) were collected monthly throughout the winter 1976/77. Samples were frozen down to selected temperatures and hardiness was estimated by visual observations of oxidative browning and bud break. In most species hardiness rapidly increased from September to November and dehardening started in February–March. In six species (Betula pubescens Ehrh., Picea abies (L.) Karst., Salix caprea L., Sorbus aucuparia L., Vaccinium myrtillus L., V. vitis-idaea L.) hardening developed faster at the continental than at the coastal location. Differences in maximum hardiness between sampling locations were generally small and there were no real differences in dehardening of the plants between the locations. Both twigs and buds of Salix pentandra L. and Populus tremula L. survived liquid nitrogen in January–February.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00441691
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  • 4
    Electronic Resource
    Electronic Resource
    Freezing avoidance by deep supercooling in hydrated lettuce seeds (1977)
    [s.l.] : Nature Publishing Group
    Nature 269 (1977), S. 325-327 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Experiments were conducted with seed of Grand Rapids lettuce. Moisture content was controlled by leaving seeds to imbibe water for specific intervals; by leaving them to imbibe in different concentrations of polyethylene glycol (molecular weight 6,000, PEG 6000) for specific intervals, and by ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/269325a0
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  • 5
    Electronic Resource
    Electronic Resource
    Agrobacterium-mediated transformation of strawberry calli and recovery of transgenic plants (1990)
    Springer
    Plant cell reports 9 (1990), S. 10-13 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transformed calli and shoots of strawberry (Fragaria × ananassa Duch.) cv. Redcoat were obtained using Agrobacterium tumefaciens carrying plasmid pB1121. Inoculated leaf explants produced transgenic calli at a frequency of 3% on selection medium containing 50 μg/ml kanamycin. Twenty per cent of selected caili regenerated, giving rise to transgenic shoots. All transgenic calli and shoots expressed substantial amounts of GUS and NPT-II activity. The Southern blot analysis confirmed the insertion of both marker genes into the strawberry genome as single and multiple copy inserts. The transgenic shoots elongated on rooting medium in the presence of 25 μg/ml kanamycin, but exhibited reduced rooting ability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232125
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  • 6
    Electronic Resource
    Electronic Resource
    Genetic transformation of strawberry by Agrobacterium tumefaciens using a leaf disk regeneration system (1990)
    Springer
    Plant cell reports 9 (1990), S. 293-298 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An efficient genetic transformation protocol has been developed for strawberry cv. Redcoat using Agrobacterium tumefadens. The protocol relies on a high frequency (84%) shoot regeneration system from leaf disks. The leaf disks were inoculated with a non-oncogenic Agrobacterium tumefadens strain MP90 carrying a binary vector plasmid pBI121 which contains a chimeric nopaline synthase (NOS) promoter driven neomycin phosphotransferase (NPT II) gene and a cauliflower mosaic virus 35S (CaMV35S) promoter driven, ß-glucuronidase (GUS) marker gene. The inoculated leaf disks, pre-cultured for 10 days on non-selective shoot regeneration medium, formed light green meristematic regions on selection medium containing 50 μg/ml kanamycin. These meristematic regions developed into transformed shoots at a frequency of 6.5% on a second selection medium containing 25 μg/ml kanamycin. The selected shoots were multiplied on shoot proliferation medium in the presence of kanamycin. All such shoots were resistant to kanamycin and expressed varying levels of NPT II and GUS enzyme activity. Histochemical assays for GUS activity indicated that the 35S promoter was highly active in meristematic cells of shoot and root apices. Molecular analysis of each transgenic clone confirmed the integration of both marker genes into the strawberry genome. Leaf disks prepared from transformed plants, when put through the second selection cycle on kanamycin, formed callus and exhibited GUS activity. The rooted transformed plants were grown in a greenhouse for further characterization. The protocol may be useful for improvement of strawberry through gene manipulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00232854
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  • 7
    Electronic Resource
    Electronic Resource
    Real-Time in Situ Monitoring of Lysozyme During Lyophilization Using Infrared Spectroscopy: Dehydration Stress in the Presence of Sucrose (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 1548-1555 
    Details
    ISSN: 1573-904X
    Keywords: FTIR spectroscopy ; attenuated total reflectance ; internal reflection ; lyophilization ; lysozyme ; sucrose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. First, to investigate the role of sucrose in stabilizing protein structure (as measured by changes in the amide I band of lysozyme) caused by dehydration encountered during lyophilization. Second, to demonstrate the utility of internal reflection spectroscopy as a tool for conducting controlled lyophilization experiments. Methods. A custom-built internal reflection FTIR accessory was used to follow the entire freeze-drying process of solutions consisting of 49.4 mg/mL lysozyme in the presence and absence of 10% sucrose in real-time. Studies were carried out using D2O as a transparent medium in the infrared region of the protein amide bands. Potential self-association of the protein in the presence of sucrose was investigated using dynamic light scattering. Hydration levels were determined using a multiple regression equation. Differential scanning calorimetry (DSC) permitted characterization of the final lyophilized product. Moisture content was determined using Karl Fischer titration. Results. Throughout freezing and drying, minimal changes were observed both in frequency (1647 ± 1 cm−1) and bandwidth (46 ± 1 cm−l) of the amide I band in the presence of sucrose. In contrast, greater changes in frequency and band width were seen in the absence of sucrose. A successfully lyophilized cake was obtained which had properties of a glass as measured by DSC, with a Tg of 50°C. The lyophilized product containing sucrose had 4% moisture by weight. Three distinct rates of water desorption were discovered during drying under vacuum (50 mg/hr within the sample temperature range from −35° to −25°C; 30 mg/hr from 10° to 25°C; 1.2 mg/hr from 27° to 38°C). Conclusions. The inclusion of sucrose served to minimize perturbations of protein structure caused by freezing and dehydration stresses encountered during lyophilization (compared to studies conducted in the absence of sucrose). The results support the water replacement hypothesis and underscore the role of the sugar in preserving a native structure in the dried state. This investigation demonstrates the usefulness of infrared spectroscopy in evaluating lyophilization process parameters and formulation design.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012170116311
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of in vitro propagation methods on field performance of two strawberry cultivars (1994)
    Springer
    Euphytica 76 (1994), S. 107-115 
    Details
    ISSN: 1573-5060
    Keywords: Fragaria x ananassa ; genetic stability ; tissue culture ; in vitro propagation methods ; strawberry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Strawberry cultivars, ‘Redcoat’ and ‘Veestar’, propagated by meristem culture (MC), callus culture (CC) and direct shoot regeneration (DR) from leaf disks were compared for their vegetative and reproductive characters with standard runner (SR) propagated plants under field conditions. In the planting year, in vitro propagated plants of both cultivars had the same number of leaves as SR plants, but in vitro propagated ‘Redcoat’ produced fewer stolons per plant than SR plants. However, in the following year, in vitro propagated mother plants of both cultivars had more leaves and higher runner production than SR mother plants. Flowering and fruiting behaviour of ‘Veestar’ was not appreciably influenced by in vitro propagation methods. However, in vitro propagated plants of ‘Redcoat’ flowered earlier and produced more flowers and fruits than SR plants, but still maintained normal berry weight. Among in vitro propagated plants, DR plants of ‘Redcoat’ were the earliest to flower, whereas MC plants produced more flowers and fruits. The field performance of the first daughter plants derived from the in vitro propagated plants was consistent with their respective mother plants. Leaf shape of both cultivars was not altered by in vitro propagation. Phenotypic abnormalities were mainly confined to occurrence of yellow leaf variants in MC and CC plants and occasional appearance of plants with irregular flowering and growth habit among CC plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024027
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  • 9
    Electronic Resource
    Electronic Resource
    Low-temperature IR spectroscopy reveals four stages of water loss during lyophilization of hen egg white lysozyme (1994)
    New York : Wiley-Blackwell
    Biopolymers 34 (1994), S. 365-370 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Water loss during lyophilization of a 49.4 mg/mL solution of lysozyme in D2O was studied with ir spectroscopy using a low-temperature, single reflection, horizontal, attenuated, total reflectance accessory. Four regions of water loss were identified and assignable to different forms of bound water. The amide I band begins to shift to higher frequency while the amide II concurrently shifts to lower frequency and broadens after the first stage of water loss (sublimation) at -10°C. Additionally, the carboxylate band (at 1584 cm-1) shifts slightly to lower frequency. A second stage at 17°C is characterized by continued shifts in the carboxylate and amide II bands to low frequency, further broadening in the amide II and greater shift to high frequency in the amide I (ascribed to the removal of periphery water around the protein). At the third stage of water loss, the carboxylate band decreases substantially in relative absorbance (consistent with the removal of water from the carbonyl backbone). In the fourth and last stage, the carboxylate band nearly disappears and water loss is very slow. Based upon a final level of hydration of 0.037 h, the last stage corresponds to 25% completion of the removal of water associated with ionizable side chains. From start to finish, the amide I shifts 9 cm-1 to higher frequency. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360340308
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