Polyamine Uptake in Carrot Cell Cultures 1
AUTOR(ES)
Pistocchi, Rossella
RESUMO
Putrescine and spermidine uptake into carrot (Daucus carota L.) cells in culture was studied. The time course of uptake showed that the two polyamines were very quickly transported into the cells, reaching a maximum absorption within 1 minute. Increasing external polyamine concentrations up to 100 millimolar showed the existence of a biphasic system with different affinities at low and high polyamine concentrations. The cellular localization of absorbed polyamines was such that a greater amount of putrescine was present in the cytoplasmic soluble fraction, while spermidine was mostly present in cell walls. The absorbed polyamines were released into the medium in the presence of increasing external concentrations of the corresponding polyamine or Ca2+. The effects of Ca2+ were different for putrescine and spermidine; putrescine uptake was slightly stimulated by 10 micromolar Ca2+ and inhibited by higher concentrations, while for spermidine uptake there was an increasing stimulation in the Ca2+ concentration range between 10 micromolar and 1 millimolar. La3+ nullified the stimulatory effect of 10 micromolar Ca2+ on putrescine uptake and that of 1 millimolar Ca2+ on spermidine uptake. La3+ at 0.5 to 1 millimolar markedly inhibited the uptake of both polyamines, suggesting that it interferes with the sites of polyamine uptake. Putrescine uptake was affected to a lesser extent by metabolic inhibitors than was spermidine uptake. It is proposed that the entry of polyamines into the cells is driven by the transmembrane electrical gradient, with a possible antiport mechanism between external and internal polyamine molecule.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1056586Documentos Relacionados
- Polyamines in Relation to Growth in Carrot Cell Cultures 1
- Characterization of Carrot and Tobacco Cell Cultures Resistant to p-Fluorophenylalanine 1
- Further Studies on the Photosynthesis of Carrot Tissue Cultures 1
- Analysis of the rolC promoter region involved in somatic embryogenesis-related activation in carrot cell cultures.
- Isolation and Properties of Deoxyribonucleic Acid from Protoplasts of Cell Suspension Cultures of Ammi visnaga and Carrot (Daucus carota) 1