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Cochicine-induced polyploidization depends on tubulin polymerization in c-metaphase cells
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Orientador(es)
Resumo(s)
The microtubule cytoskeleton plays a crucial role in the
cell cycle and in mitosis. Colchicine is a microtubule-depolymerizing
agent that has long been used to induce chromosome individualization
in cells arrested at metaphase and also in the induction of polyploid
plants. Although attempts have been made to explain the processes
and mechanisms underlying polyploidy induction, the role of the cytoskeleton
still remains largely unknown. Through immunodetection
of alpha-tubulin, different concentrations (0.5 or 5 mM) of colchicine
were found to produce opposite effects in the organization of the cytoskeleton
in rye (Secale cereale L.). A low concentration (0.5 mM)
induced depolymerization of the microtubular cytoskeleton in all
phases of the cell cycle. In contrast, a high concentration (5 mM) was
found to induce the polymerization of new tubulin-containing structures
in c-metaphase cells. Furthermore, both treatments also showed
contrasting effects in the induction of polyploid cells. Flow cytometric
analysis and quantitative assessments of nucleolus-organizing regions
revealed that only the high-concentration colchicine treatment was effective
in the formation of polyploid cells. Our studies indicate that
spindle disruption alone is insufficient for the induction of polyploid
cells. The absence of any tubulin structures in plants treated with
colchicine at the low concentration induced cell anomalies, such as
the occurrence of nuclei with irregular shape and/or (additional) micronuclei,
12 h after recovery, pointing to a direct effect on cell viability.
In contrast, the almost insignificant level of cell anomalies in the
high-concentration treatment suggests that the presence of new tubulin-
containing structures allows the reconstitution of 4C nuclei and
their progression into the cell cycle.
Descrição
Palavras-chave
induced polyploidy colchicine tubulin array Secale cereale
Contexto Educativo
Citação
"Protoplasma". 227 (2006) 147-153