The use of TTC reduction assay for assessment of Gentiana spp. cell suspension viability after cryopreservation |
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Authors: | Anna Miku?a Maciej Niedzielski Jan J Rybczyski |
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Institution: | (1) Botanical Garden — Center for Biological Diversity Conservation, Polish Academy of Sciences, ul. Prawdziwka 2, 02-973 Warsaw, Poland |
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Abstract: | This study was aimed at improving the 2,3,5-triphenyl-tetrazoliumchloride (TTC) reduction test for initial assessment of cell
survival after cryopreservation. Experiments were carried out on three embryogenic cell suspensions of different ages: 9-year-old
Gentiana tibetica (King ex Hook. F.), 2-year-old G. kurroo (Royle), and 1-year-old G. cruciata (L.). The suspensions were maintained in MS medium supplemented with 1.0 mg 1−1 3,6-dichloro-o-anisic acid, 0.1 mg 1−1 naphthaleneacetic acid, 2.0 mg l−1 6-benzylaminopurine, 80.0 mg 1−1 adenine sulphate and 0.09 M sucrose. Four weeks before freezing, part of the tissue was subcultured to the same medium with
sucrose concentrations elevated from 0.09 M (3%sMS) to 0.175 M (6%sMS) or 0.26 M (9%sMS).
In freezing treatments without cryoprotection, tissue was plunged directly into liquid nitrogen (LN) or cooled gradually.
In freezing treatments with cryoprotection, the cells were pretreated with 1 M sucrose, or with 0.4 M sorbitol + 0.25 M proline
or + 0.08 M DMSO, or with vitrification solution (PVS2). Encapsulation was another variant.
TTC reduction activity was spectrophotometrically assessed immediately, 1, 3, 5, 24 and 48 h after thawing. Cells without
cryoprotection were lethally damaged, but TTC reduction activity in those cells ranged from 6.5% (tissue from 3%sMS) to 73
% (tissue from 9%sMS) directly after thawing. Formazan production was reduced to zero after 24 h. The TTC test showed 50%
formazan content immediately after thawing of DMSO-protected G. tibetica tissue, but only 22.47% after 24 h and 2.9% after 48 h. Ultrastructural analysis of those cells showed lethal damage in many
of them. For the PVS2 treatment, the formazan content was similar in samples analyzed directly after thawing and 24 h later.
Cells treated with PVS2 did not show structural disturbances. Encapsulated cell aggregates of G. cruciata treated with concentrations of sucrose increasing up to 1 M produced 2.6 times more formazan. When applied at least 48 h
after thawing, the TTC test can reflect cell viability and can be used to compare the effectiveness of cryoprotectant performance
and freezing protocols, but it must be carefully evaluated, with appropriate controls. |
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Keywords: | cell suspension culture cryopreservation Gentiana TTC test ultrastructure |
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