C4 plants have up to 10-fold higher apparent CO2 assimilation rates than the most productive C3 plants. This requires higher fluxes of metabolic intermediates across the chloroplast envelope membranes of C4 plants in comparison with those of C3 plants. In particular, the fluxes of metabolites involved in the biochemical inorganic carbon pump of C4 plants, such as malate, pyruvate, oxaloacetate,...

Serum C3 and C4 levels have been measured in healthy subjects and patients with hepatitis, cirrhosis of the liver and liver cancer. A significant elevation of serum C4 was found in liver cancer and reduction in cirrhosis. There was a direct correlation between bilirubin levels and C3 in hepatitis and serum albumin and C3 in cirrhosis. Serum C4 appears to be a more sensitive indicator of liver d...

An hypothesis was formulated that phosphorus (P) partitioning in tissues of C4 leaves would permit C4 plants to resist P deficiency better than C3 plants. To test this hypothesis, 12 C3, C4, and C3-C4 intermediate species were grown at adequate, deficient, and severely deficient P supply in a solid-phase-buffered sand culture system to characterize photosynthetic and growth responses. Species d...

C4 photosynthesis is a carbon-concentrating mechanism that evolved independently more than 60 times in a wide range of angiosperm lineages. Among other alterations, the evolution of C4 from ancestral C3 photosynthesis requires changes in the expression of a vast number of genes. Differential gene expression analyses between closely related C3 and C4 species have significantly increased our unde...

Rubisco (for ribulose-1,5-bisphosphate carboxylase/oxygenase), the enzyme that catalyzes the first major step in carbon fixation, is notoriously inefficient in this role, owing to its function as an oxygenase as well as a carboxylase. Photorespiration, the pathway followed when Rubisco catalyzes the oxygenation rather than carboxylation of the substrate ribulose-1,5-bisphosphate, can reduce the...