The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
John D. Hamill - One of the best experts on this subject based on the ideXlab platform.
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Cryopreservation and post freeze molecular and biosynthetic stability in transformed roots of Beta vulgaris and Nicotiana rustica
Plant Cell Tissue and Organ Culture, 1991Co-Authors: Erica E. Benson, John D. HamillAbstract:Crypopreservation methods were firstly developed for root-tips from hairy root cultures of Beta vulgaris , established after transformation by Agrobacterium rhizogenes . The effects of culture age, pre-growth, Cryoprotection, freezing rate and post-freeze culture conditions were determined. The resulting freezing protocol was then used to cryopreserve transformed root cultures of Nicotiana rustica . Both species were viable after freezing (ca. 80%), according to fluorescein diacetate vital staining. However, on average the regeneration of proliferating roots from surviving root-tips was low (
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cryopreservation and post freeze molecular and biosynthetic stability in transformed roots of beta vulgaris and nicotiana rustica
Plant Cell Tissue and Organ Culture, 1991Co-Authors: Erica E. Benson, John D. HamillAbstract:Crypopreservation methods were firstly developed for root-tips from hairy root cultures of Beta vulgaris, established after transformation by Agrobacterium rhizogenes. The effects of culture age, pre-growth, Cryoprotection, freezing rate and post-freeze culture conditions were determined. The resulting freezing protocol was then used to cryopreserve transformed root cultures of Nicotiana rustica. Both species were viable after freezing (ca. 80%), according to fluorescein diacetate vital staining. However, on average the regeneration of proliferating roots from surviving root-tips was low (<20%). Growth rates, secondary metabolite production and T-DNA structure of a number of hairy root lines were examined and found to be unchanged after cryopreservation.
Erica E. Benson - One of the best experts on this subject based on the ideXlab platform.
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Cryopreservation and post freeze molecular and biosynthetic stability in transformed roots of Beta vulgaris and Nicotiana rustica
Plant Cell Tissue and Organ Culture, 1991Co-Authors: Erica E. Benson, John D. HamillAbstract:Crypopreservation methods were firstly developed for root-tips from hairy root cultures of Beta vulgaris , established after transformation by Agrobacterium rhizogenes . The effects of culture age, pre-growth, Cryoprotection, freezing rate and post-freeze culture conditions were determined. The resulting freezing protocol was then used to cryopreserve transformed root cultures of Nicotiana rustica . Both species were viable after freezing (ca. 80%), according to fluorescein diacetate vital staining. However, on average the regeneration of proliferating roots from surviving root-tips was low (
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cryopreservation and post freeze molecular and biosynthetic stability in transformed roots of beta vulgaris and nicotiana rustica
Plant Cell Tissue and Organ Culture, 1991Co-Authors: Erica E. Benson, John D. HamillAbstract:Crypopreservation methods were firstly developed for root-tips from hairy root cultures of Beta vulgaris, established after transformation by Agrobacterium rhizogenes. The effects of culture age, pre-growth, Cryoprotection, freezing rate and post-freeze culture conditions were determined. The resulting freezing protocol was then used to cryopreserve transformed root cultures of Nicotiana rustica. Both species were viable after freezing (ca. 80%), according to fluorescein diacetate vital staining. However, on average the regeneration of proliferating roots from surviving root-tips was low (<20%). Growth rates, secondary metabolite production and T-DNA structure of a number of hairy root lines were examined and found to be unchanged after cryopreservation.
Jon P Costanzo - One of the best experts on this subject based on the ideXlab platform.
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Cryoprotection by urea in a terrestrially hibernating frog.
The Journal of experimental biology, 2020Co-Authors: Jon P CostanzoAbstract:The role of urea as a balancing osmolyte in osmotic adaptation is well known, but this 'waste product' also has myriad other functions in diverse taxa. We report that urea plays an important, previously undocumented role in freezing tolerance of the wood frog (Rana sylvatica), a northern woodland species that hibernates terrestrially in sites where dehydration and freezing may occur. Wood frogs inhabiting an outdoor enclosure accumulated urea to 65 mmol l-1 in autumn and early winter, when soil moisture was scarce, but subsequently urea levels fell to approximately 2 mmol l-1 as the availability of environmental water increased. Laboratory experiments showed that hibernating R. sylvatica can accumulate at least 90 mmol l-1 urea under relatively dry, warm conditions. During experimental freezing, frogs synthesized glucose but did not accumulate additional urea. Nevertheless, the concentrations of urea and glucose in some tissues were similar. We tested urea's efficacy as a cryoprotectant by measuring lysis and lactate dehydrogenase (LDH) leakage in samples of R. sylvatica erythrocytes frozen/thawed in the presence of physiological levels of urea or other osmolytes. In conferring protection against freeze/thaw damage, urea was comparable to glycerol and as good as or better than glucose, cryoprotectants found in freeze-tolerant frogs and other animals. Urea treatment also improved the viability of intact tissues frozen in vitro, as demonstrated by post-thaw measures of metabolic activity and LDH leakage. Collectively, our findings suggest that urea functions both as an osmoprotectant and a cryoprotectant in terrestrially hibernating amphibians.
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Cryoprotection by urea in a terrestrially hibernating frog
The Journal of Experimental Biology, 2005Co-Authors: Jon P CostanzoAbstract:The role of urea as a balancing osmolyte in osmotic adaptation is well known, but this ‘waste product’ also has myriad other functions in diverse taxa. We report that urea plays an important, previously undocumented role in freezing tolerance of the wood frog (Rana sylvatica), a northern woodland species that hibernates terrestrially in sites where dehydration and freezing may occur. Wood frogs inhabiting an outdoor enclosure accumulated urea to 65·mmol·l ‐1 in autumn and early winter, when soil moisture was scarce, but subsequently urea levels fell to ~2·mmol·l ‐1 as the availability of environmental water increased. Laboratory experiments showed that hibernating R. sylvatica can accumulate at least 90·mmol·l ‐1 urea under relatively dry, warm conditions. During experimental freezing, frogs synthesized glucose but did not accumulate additional urea. Nevertheless, the concentrations of urea and glucose in some tissues were similar. We tested urea’s efficacy as a cryoprotectant by measuring lysis and lactate dehydrogenase (LDH) leakage in samples of R. sylvatica erythrocytes frozen/thawed in the presence of physiological levels of urea or other osmolytes. In conferring protection against freeze/thaw damage, urea was comparable to glycerol and as good as or better than glucose, cryoprotectants found in freezetolerant frogs and other animals. Urea treatment also improved the viability of intact tissues frozen in vitro, as demonstrated by post-thaw measures of metabolic activity and LDH leakage. Collectively, our findings suggest that urea functions both as an osmoprotectant and a cryoprotectant in terrestrially hibernating amphibians. Summary
Locksley E Mcgann - One of the best experts on this subject based on the ideXlab platform.
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Cryoprotection in plant tissues related to reduced volume expansion of cryoprotectant solution.
Cryo letters, 2020Co-Authors: Takashi Suzuki, Daisuke Kami, Katsuji Oosawa, Locksley E McgannAbstract:To clarify the mechanism of reduced volume expansion-related Cryoprotection changes in solution volume during freezing using several types of cryoprotectant were investigated. The effect of each cryoprotectant solution on the survival of asparagus nodal segments cooled slowly (0.5 degrees C/min) to -40 degrees C was also examined. The ratio of the volume at -40 degrees C to the volume at +20 degrees C was used as an index for expansion, calculated as a ratio of the density at +20 degrees C to the density at -40 degrees C. Distilled, deionized water showed the largest volume change at a ratio of 1.094. The ratio gradually decreased with an increase in the molar concentration of cryoprotectant, with the magnitude of the change dependent on the nature of the cryoprotectant. Raffinose was the most effective in reducing volume expansion when compared with other cryoprotectants at a same concentration. Raffinose exhibited greatest Cryoprotection in asparagus tissue at 0.6 M where the solution became saturated. Dimethyl sulfoxide (Me2SO) at 1.69 M had the largest effect on cryoprotecting asparagus tissue. Furthermore, Me2SO was also the most effective in reducing volume expansion among the group of cryoprotectants permeable to the plasma membrane. It is concluded that Cryoprotection in tissues was closely related to reduced volume expansion especially at low concentration (< or = 1.0 M). Cryoprotectants of impermeable sugar group lost their cryoprotective effect at > 1.0 M, which may due to severe dehydration and cell damage occurred in hypertonic solution. Useful cryoprotectants should be furnished with high ability of reducing volume expansion during freezing as well as low toxicity and high permeability for cells.
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Cryoprotection in plant tissues related to reduced volume expansion of cryoprotectant solution
Cryo letters, 2005Co-Authors: Takashi Suzuki, Daisuke Kami, Katsuji Oosawa, Locksley E McgannAbstract:To clarify the mechanism of reduced volume expansion-related Cryoprotection changes in solution volume during freezing using several types of cryoprotectant were investigated. The effect of each cryoprotectant solution onthe survival of asparagus nodal segments cooled slowly (0.5°C/min) to -40°C was also examined. The ratio of the volume at -40°C to the volume at +20°C was used as an index for expansion, calculated as a ratio of the density at +20°C to the density at -40°C. Distilled, deionized water showed the largest volume change at a ratio of 1.094. The ratio gradually decreased with an increase in the molar concentration of cryoprotectant, with the magnitude of the change dependent on the nature of the cryoprotectant. Raffinose was the most effective in reducing volume expansion when compared with other cryoprotectants at a same concentration. Raffinose exhibited greatest Cryoprotection in asparagus tissue at 0.6 M where the solution became saturated. Dimethyl sulfoxide (Me 2 SO) at 1.69 M had the largest effect on cryoprotecting asparagus tissue. Furthermore, Me2SO was also the most effective in reducing volume expansion among the group of cryoprotectants permeable to the plasma membrane. It is concluded that Cryoprotection in tissues was closely related to reduced volume expansion especially at low concentration (≤1.0 M). Cryoprotectants of impermeable sugar group lost their cryoprotective effect at >1.0 M, which may due to severe dehydration and cell damage occurred in hypertonic solution. Useful cryoprotectants should be furnished with high ability of reducing volume expansion during freezing as well as low toxicity and high permeability for cells.
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mechanisms of cryoinjury and Cryoprotection in split thickness skin
Cryobiology, 1996Co-Authors: M A J Zieger, Edward E Tredget, Locksley E McgannAbstract:Successful cryopreservation of tissues will ultimately require a more detailed understanding of how thein situenvironment modifies cell responses during cooling and warming. Low-temperature responses of porcine split-thickness skin and isolated basal keratinocytes were compared after various cooling protocols and in the presence and absence of cryoprotectants. Recovery was assessed by measuring oxygen consumption kinetics in skin and tetrazolium reduction in isolated cells. Freeze substitution was used to visualize ice nucleation and growth in skin. The results indicated that the time required for diffusion of water in split-thickness skin delayed osmotic responses in the basal keratinocytes and resulted in increased intracellular and intercellular ice formation. Rapid cooling (−200°C/min) in the presence of cryoprotectants resulted in a reduction in the number of cells containing ice and the size of the intercellular ice crystals and an increase in tissue recovery. These observations support other reports which suggest that cell-to-cell and cell-to-substrate interactions are sensitive sites for cryoinjury. A practical recommendation from this study is that high recovery of split-thickness skin may be achieved with protocols using high cooling rates.
B. V. Ford-lloyd - One of the best experts on this subject based on the ideXlab platform.
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Cryopreservation of embryogenic calli of cassava using sucrose Cryoprotection and air desiccation
Plant Cell Reports, 2004Co-Authors: K. E. Danso, B. V. Ford-lloydAbstract:A simplified technique which simultaneously induces and cryoprotects embryogenic calli using sucrose followed by dehydration was developed for the cryopreservation of cassava genetic resources. An initial experiment to optimise the sucrose concentration needed for both embryo production and Cryoprotection showed that higher concentrations of sucrose—between 0.4 M and 0.5 M —significantly reduced the viability as well as the number of embryos produced by the embryogenic clumps in the absence of freezing. Post-thaw viability as well as embryogenic competence of clumps depended on the percentage moisture lost, duration of exposure to higher sucrose concentrations and the duration of induction of embryogenic clumps. Extending the period of Cryoprotection to 21 days coupled with increased moisture loss (greater than 75%) significantly increased both post-thaw viability and the embryogenic competence of cryopreserved clumps to 95%, while reducing the duration decreased post-thaw viability. Cryopreserved callus clumps developed secondary and cyclic embryos similar to those of the non-cryopreserved controls. The optimised protocol was successfully applied to SM_1-2075-1 Line 1 somatic embryos. The rate of plant recovery from cryopreserved embryos of both TME 9 and SM_1-2075-1 Line 1 was comparable to that of the non-cryopreserved embryos. Successful cryopreservation of embryogenic clumps of cassava can be used to establish in vitro genebanks for long-term conservation of cassava genetic resources to complement field genebanks and other in vitro methods already being used.