Induction of HCO3− Transporting Capability and High Photosynthetic Affinity to Inorganic Carbon by Low Concentration of CO2 in Anabaena variabilis1

AUTOR(ES)
RESUMO

The apparent affinity of photosynthesis for inorganic carbon in Anabaena variabilis strain M-3 increased during the course of adaptation from high to low CO2 concentration (5% and 0.03% v/v CO2 in air, respectively). This was attributed to an increased ability of the cells to accumulate inorganic carbon during the course of adaptation to low CO2 conditions. The release of phycobiliproteins was used to evaluate the sensitivity of the cells to lysozyme treatment followed by osmotic shock. High CO2-grown cells were more sensitive to this treatment than were low CO2 ones. The efflux of inorganic carbon from cells preloaded with radioactive bicarbonate is faster in high than it is in low CO2-adapted cells. It is postulated that the cell wall or membrane components undergo changes during the course of adaptation to low CO2 conditions. This is supported by electron micrographs showing differences in the cell wall appearance between high and low CO2-grown cells. The increasing ability to accumulate HCO3− and the lessened sensitivity to lysozyme during adaptation to low CO2 conditions depends on protein synthesis. The increase in affinity for inorganic carbon during the adaptation to low CO2 conditions is severely inhibited by the presence of spectinomycin. Incubation in the light significantly lessens the time required for the adaptation to low CO2 conditions.

ACESSO AO ARTIGO

Documentos Relacionados