Publications by authors named "A L Cousins"
Phosphoenolpyruvate (PEP) carboxylase (PEPC) has an anaplerotic role in central plant metabolism but also initiates the carbon concentrating mechanism during C photosynthesis. The C PEPC has different binding affinities (K) for PEP (K) and HCO (K), and allosteric regulation by glucose-6-phosphate (G6-P) compared to non-photosynthetic isoforms. These differences are linked to specific changes in amino acids within PEPC.
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- The measurement of leaf water use efficiency (WUEi) can be tricky, but analyzing leaf carbon isotope composition (δ13Cleaf) offers a promising method for large-scale screening of this trait in plants.
- In C4 plants, the complex relationship between δ13Cleaf and WUEi is due to CO2-concentrating mechanisms, yet genetic variation in δ13Cleaf exists among different C4 species.
- By studying two specific recombinant inbred lines of maize with different δ13Cleaf values, researchers found that faster stomatal responses to CO2 and light changes led to better WUEi, highlighting the importance of stomatal kinetics in enhancing water use efficiency.
Consumers often cite cognitive improvements as reasons for making dietary changes or using dietary supplements, a motivation that if leveraged could greatly enhance public health. However, rarely is it considered whether standardized cognitive tests that are used in nutrition research are aligned to outcomes of interest to the consumer. This knowledge gap presents a challenge to the scientific substantiation of nutrition-based cognitive health benefits.
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- Leaf plastids are crucial for photosynthesis and other metabolic processes in plants, and understanding their functions is linked to studying their size and volume.
- Researchers developed three microscopy techniques to measure the in situ volumes of chloroplasts, using chlorophyll fluorescence, a CFP marker, and serial block-face scanning electron microscopy.
- The study found that average volumes for mesophyll chloroplasts and guard cell plastids were 93 μm and 18 μm respectively, with chlorophyll fluorescence proving to be a reliable method for volume measurement, especially for labs lacking advanced equipment.
Article Synopsis
- The study investigates the two PEPC genes in two C4 grasses, Panicum miliaceum and Echinochloa colona, which typically possess one highly expressed PEPC gene that facilitates the carbon-concentrating mechanism in C4 photosynthesis.
- Researchers synthesized coding sequences for the PEPC proteins from both grasses, performed point mutations, and analyzed their kinetic properties using advanced techniques.
- Results showed that PEPCs in P. miliaceum were highly similar and had similar kinetic properties, whereas the PEPCs in E. colona had notable differences, particularly in how they responded to allosteric regulators, suggesting evolutionary variations.