Background-We have recently demonstrated that activity of red blood cell glutathione peroxidase-1 is inversely associated with the risk of cardiovascular events in patients with coronary artery disease. The present study analyzed the effect of glutathione peroxidase-1 deficiency on atherogenesis in the apolipoprotein E-deficient mouse. Methods and Results-Female apolipoprotein E-deficient mice with and without glutathione peroxidase-1 deficiency were placed on a Western-type diet for another 6, 12, or 24 weeks. After 24 weeks on Western-type diet, double-knockout mice (GPx-1 Ϫ/Ϫ ApoE Ϫ/Ϫ ) developed significantly more atherosclerosis than control apolipoprotein E-deficient mice. Moreover, glutathione peroxidase-1 deficiency led to modified atherosclerotic lesions with increased cellularity. Functional experiments revealed that glutathione peroxidase-1 deficiency leads to increased reactive oxygen species concentration in the aortic wall as well as increased overall oxidative stress. Peritoneal macrophages from double-knockout mice showed increased in vitro proliferation in response to macrophage-colony-stimulating factor. Also, we found lower levels of bioactive nitric oxide as well as increased tyrosine nitration as a marker of peroxynitrite production. Key Words: antioxidants Ⅲ atherosclerosis Ⅲ nitric oxide O xidative stress is defined as an imbalance between the production and degradation of reactive oxygen species (ROS). Enzymatic inactivation of ROS is achieved mainly by superoxide dismutases, catalase and the glutathione peroxidases. 1 Indeed, glutathione and the glutathione peroxidases constitute the principal antioxidant defense system in mammalian cells. [2][3][4] Glutathione peroxidase-1 (GPx-1), the ubiquitous intracellular form and key antioxidant enzyme within many cells, including the endothelium, consumes reduced glutathione to convert hydrogen peroxide to water and lipid peroxides to their respective alcohols. 5 It also acts as a peroxynitrite reductase. 6 Because of its major role in the prevention of oxidative stress, GPx-1 may be an important antiatherogenic enzyme. 7 In fact, we have recently shown in patients with coronary artery disease that a low activity of red blood cell GPx-1 is associated with an increased risk of cardiovascular events independently from traditional risk factors or atherosclerosis. 8 A mouse model of GPx-1 deficiency is available. These animals appear healthy and are fertile. 9 However, a recent in vitro study showed increased cell-mediated oxidation of low-density lipoprotein (LDL) in this model. 10 Furthermore, GPx-1 deficiency causes endothelial dysfunction in mice 11 that is aggravated by hyperhomocysteinemia. 12 GPx-1 deficiency is accompanied by increased periadventitial inflammation, neointima formation, and collagen deposition surrounding the coronary arteries. 13 GPx-1 activity is decreased or absent in carotid atherosclerotic plaques, and the absence of GPx-1 activity in atherosclerotic lesions has been linked to the development of more severe lesions in...

Grafting is a centuries-old technique used in plants to obtain economic benefits. Grafting increases nutrient uptake and utilization efficiency in a number of plant species, including fruits, vegetables, and ornamentals. Selected rootstocks of the same species or close relatives are utilized in grafting. Rootstocks absorb more water and ions than self-rooted plants and transport these water and ions to the aboveground scion. Ion uptake is regulated by a complex communication mechanism between the scion and rootstock. Sugars, hormones, and miRNAs function as long-distance signaling molecules and regulate ion uptake and ion homeostasis by affecting the activity of ion transporters. This review summarizes available information on the effect of rootstock on nutrient uptake and utilization and the mechanisms involved. Information on specific nutrient-efficient rootstocks for different crops of commercial importance is also provided. Several other important approaches, such as interstocking (during double grafting), inarching, use of plant-growth-promoting rhizobacteria, use of arbuscular mycorrhizal fungi, use of plant growth substances (e.g., auxin and melatonin), and use of genetically engineered rootstocks and scions (transgrafting), are highlighted; these approaches can be combined with grafting to enhance nutrient uptake and utilization in commercially important plant species. Whether the rootstock and scion affect each other's soil microbiota and their effect on the nutrient absorption of rootstocks remain largely unknown. Similarly, the physiological and molecular bases of grafting, crease formation, and incompatibility are not fully identified and require investigation. Grafting in horticultural crops can help reveal the basic biology of grafting, the reasons for incompatibility, sensing, and signaling of nutrients, ion uptake and transport, and the mechanism of heavy metal accumulation and restriction in rootstocks. Ion transporter and miRNA-regulated nutrient studies have focused on model and non-grafted plants, and information on grafted plants is limited. Such information will improve the development of nutrient-efficient rootstocks.

Summary• Brassinosteroids (BRs) play a vital role in plant growth, stress tolerance and productivity. Here, the involvement of BRs in the regulation of CO 2 assimilation and cellular redox homeostasis was studied.• The effects of BRs on CO 2 assimilation were studied in cucumber (Cucumis sativus) through the analysis of the accumulation of H 2 O 2 and glutathione and photosynthesis-related enzyme activities using histochemical and cytochemical detection or a spectrophotometric assay, and Rubisco activase (RCA) using western blot analysis and immunogold labeling.• Exogenous BR increased apoplastic H 2 O 2 accumulation, the ratio of reduced to oxidized glutathione (GSH:GSSG) and CO 2 assimilation, whereas a BR biosynthetic inhibitor had the opposite effects. BR-induced CO 2 assimilation was decreased by a H 2 O 2 scavenger or inhibition of H 2 O 2 generation, GSH biosynthesis and the NADPH-generating pentose phosphate pathway. BR-, H 2 O 2 -or GSH-induced CO 2 assimilation was associated with increased activity of enzymes in the Benson-Calvin cycle. Immunogold labeling and western blotting showed that BR increased the content of RCA and this effect was blocked by inhibitors of redox homeostasis.• These results strongly suggest that BR-induced photosynthesis involves an H 2 O 2 -mediated increase in the GSH:GSSG ratio, which may positively regulate the synthesis and activation of redox-sensitive enzymes in carbon fixation.