Influence of Ca 2+ on Blue Light-Inhibition of Glucose Uptake in a Colorless Mutant of Chlorella

Abstract

Summary The addition of Ca2+ enhanced glucose uptake in a colorless mutant of Chlorella kessleri, Fott et Novakova, no. 9.80. Hexose uptake is accompanied with H+ symport and K+ efflux, both of which were also enhanced in the presence of exogenous Ca2+. As reported previously, blue light inhibited hexose uptake in the above wild type and colorless mutant. The inhibition of H+ symport and K+ efflux accompanied with hexose uptake was also observed in mutant cells irradiated with blue light. In the presence of exogenous Ca2+; however, this inhibitory effect on hexose uptake was significantly protected; exogenous 5 mM Ca2+ protected blue light-inhibition by ca. 40-50%. The roles of Ca2+ and blue light in the hexose uptake system are discussed.