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M I Orús

Publications and source records attributed to M I Orús.

6 recordsLinked to original sources
PubMed2001

Changes in carboxysome structure and grouping and in photosynthetic affinity for inorganic carbon in Anabaena strain PCC 7119 (Cyanophyta) in response to modification of CO2 and Na+ supply.

In ANABAENA: PCC 7119 a 4-fold decrease in the value of the apparent photosynthetic affinity for external inorganic carbon [K1/2 (Ci)] occurred between 9 and 12 h after the transfer from high-CO2 (2% CO2-enriched air) to air-growing conditions. A slight increase in carboxysome frequency occurred, but during this transition their appearance and distribution remained unchanged. ANABAENA: PCC 7119 did not improve its K1/2 (Ci) beyond the above cited level of acclimation neither by culturing the cyanobacteria in Na+-deficient medium in air nor by aeration with CO2-depleted air. In air-grown cultures, Na+ deficiency induced a large increase in carboxysome frequency and an alteration of their appearance: the greatest proportion were electron-dense whereas this type constituted a minority in high-CO2 and in air, Na+-sufficient conditions. It also induced major changes in carboxysome distribution, whereby more than 60% were grouped, compared with only 10% in high-CO2 and in air, Na+-sufficient conditions. These changes in carboxysome expression were extremely rapid, occurring mainly during the first 2 h.

Anabaena↗
PubMed1991

Interactions between Glucose and Inorganic Carbon Metabolism in Chlorella vulgaris Strain UAM 101.

Chlorella vulgaris strain UAM 101 has been isolated from the effluent of a sugar refinery. This alga requires glucose to achieve maximal growth rate even under light saturating conditions. The growth rate of cultures grown on light + CO(2) + glucose (3.16 per day) reaches the sum of those grown on light + CO(2) (1.95 per day) and on dark + glucose (1.20 per day). Unlike other Chlorella strains, uptake of glucose (about 2 micromoles per milligram dry weight per hour) was induced to the same extent in the light and dark and was not photosensitive. The rate of dark respiration was not affected by light and was strongly stimulated by the presence of glucose (up to about 40% in 4 hours). The rate of photosynthetic O(2) evolution was measured as a function of the CO(2) concentration. These experiments were conducted with cells which experienced different concentrations of CO(2) or glucose during growth. The maximal photosynthetic rate was inhibited severely by growing the cells in the presence of glucose. A rather small difference in the apparent photosynthetic affinity for extracellular inorganic carbon (from 10-30 micromolar) was found between cells grown under low and high CO(2). Growth with glucose induced a reduction in the apparent affinity (45 micromolar) even though cells had not been provided with CO(2). Experiments performed at different pH values indicate CO(2) as the major carbon species taken from the medium by Chlorella vulgaris UAM 101.

Journal Article↗