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Ponencias en congresos:
Invariance of the glass transition temperature of plant vitrification solutions with cooling rate
Año:2012
Áreas de investigación
  • Transiciones de fase estructurales,
  • Biodiversidad,
  • Producción vegetal
Datos
Descripción
Glass, the state of matter where molecular mobility is so reduced that most physicochemical processes are virtually detained (including ice formation), is basic for cryopreservation. The glass transition temperature (Tg), a temperature range at which supercoooled liquid becomes glass, is characterized by a change in heat capacity (Cp), evaluated at its inflection point. Vitrification in cryopreservation protocols is achieved, without sophisticated cooling equipment, simply plunging specimens into liquid nitrogen (LN) after a set of physicochemical treatments increasing cytoplasmatic microviscosity and enhancing tissue resistance to cold and dehydration. Quick cooling is required to achieve vitrification avoiding ice formation. Both Tg and Cp are generally considered dependent on cooling rate (e.g. Angell et al. 82 (1978) J. Phys. Chem., 2622; Debenedetti et al. 410 (2001) Nature 259). The present work endeavors to increase knowledge in this area characterizing the calorimetric glass transition of the most common plant vitrification solutions, under a wide range of cooling rates. The solutions studied were Plant Vitrification Solutions 1, 2 and 3: (Uragami et al. 8 (1989) Plant Cell Rep. 418; Sakai et al. 9 (1990) Plant Cell Rep. 30; Nishizawa et al. 91 (1993) Plant Sci. 67). Cooling was performed using the calorimeter control (5, 10 and 20 ?C min?1), or for higher rates, by quenching closed pans with PVS in LN, either naked (? 5580 ?C min?1) or inside cryovials (360 ?C min?1). Quenched pans were then transferred to the pre-cooled sample chamber. Glass transition temperature was observed by DSC with a TA 2920 instrument, upon warming pans with solution samples from ?145 ?C to room temperature, at standard warming rate: 10 ?C min?1. Glass transitions showed clear and consistent temperature differences among vitrification solutions, related to composition and water content. Roughly, two sets of Tg values were obtained, for PVS1 and 2, at ?112 ?C and ?114 ?C, respectively, and for PSV3, at ?90 ?C. The observed Tg did not significantly change within a wide range of cooling rates (from 5 to 20 ?C min?1). The highest cooling rate (5580 ?C min?1) increased glass transition temperature significantly, compared to the values at the slowest cooling rates (5?20?C min?1). This change in Tg inflexion (by 1.2 ?C min?1) did not influence considerably the glass transition region because the whole transition interval was, on average, 7 ?C. However, no significant differences were found between Tg obtained with the highest cooling rate and that with the middle cooling rate (360 ?C min?1). In conclusion, Tg of plant vitrification solutions did not significantly change when the cryopreservation methods based on either direct plunging samples into liquid nitrogen or plunging of samples in closed cryovials were used. We can conclude that the Tg of commonly used PVSs did not change with the cooling rates tested.
Internacional
No
Nombre congreso
49th Annual Meeting of the Society of Cryobiology
Tipo de participación
960
Lugar del congreso
Rosario (Argentina)
Revisores
Si
ISBN o ISSN
0011-2240
DOI
Fecha inicio congreso
03/06/2012
Fecha fin congreso
06/06/2012
Desde la página
347
Hasta la página
347
Título de las actas
Cryobiology vol 65
Esta actividad pertenece a memorias de investigación
Participantes
  • Participante: A.S. Texeira
  • Participante: M. Faltus
  • Participante: J. Zámecn¿k
  • Autor: R. Kotkova
  • Autor: M. Elena Gonzalez Benito (UPM)
  • Autor: A.D. Molina-García (CSIC)
Grupos de investigación, Departamentos, Centros e Institutos de I+D+i relacionados
  • Creador: Grupo de Investigación: Biodiversidad y conservación de recursos fitogenéticos
  • Departamento: Biología Vegetal
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