The Physiology and Proteomics of Drought Tolerance in Maize: Early Stomatal Closure as a Cause of Lower Tolerance to Short-Term Dehydration?

Understanding the response of a crop to drought is the first step in the breeding of tolerant genotypes. In our study, two maize (Zea mays L.) genotypes with contrasting sensitivity to dehydration were subjected to moderate drought conditions. The subsequent analysis of their physiological parameters revealed a decreased stomatal conductance accompanied by a slighter decrease in the relative water content in the sensitive genotype. In contrast, the tolerant genotype maintained open stomata and active photosynthesis, even under dehydration conditions. Drought-induced changes in the leaf proteome were analyzed by two independent approaches, 2D gel electrophoresis and iTRAQ analysis, which provided compatible but only partially overlapping results. Drought caused the up-regulation of protective and stress-related proteins (mainly chaperones and dehydrins) in both genotypes. The differences in the levels of various detoxification proteins corresponded well with the observed changes in the activities of antioxidant enzymes. The number and levels of up-regulated protective proteins were generally lower in the sensitive genotype, implying a reduced level of proteosynthesis, which was also indicated by specific changes in the components of the translation machinery. Based on these results, we propose that the hypersensitive early stomatal closure in the sensitive genotype leads to the inhibition of photosynthesis and, subsequently, to a less efficient synthesis of the protective/detoxification proteins that are associated with drought tolerance

Meloxicam, a Cyclooxygenase-2 Inhibitor, Stimulates Myelopoiesis in Irradiated Mice Via Induction of G-CSF

Meloxicam, a non-steroidal anti-inflammatory drug acting on the principle of cyclooxygenase-2 inhibition and having an improved side-effect profile in terms of the gastrointestinal toxicity, has been found to stimulate hematopoiesis in whole-body sub-lethally or mid-lethally gamma-irradiated mice. Studies on mechanisms of the hematopoiesis-stimulating action of meloxicam have revealed elevated serum levels of granulocyte colony-stimulating factor (G-CSF) within the interval of 24 hours after the administration of the drug. Induction of production of G-CSF may be, thus, supposed to be at least partially responsible for the observed beneficial effects of meloxicam in mice with radiation-induced myelosuppression. This work was supported by the Grant Agency of the Academy of Sciences of the Czech Republic (Grant No. 1QS500040507)