Established and proposed roles of xanthine oxidoreductase in oxidative and reductive pathways in plants

Xanthine oxidoreductase (XOR) is among the most-intensively studied enzymes known to participate in the consumption of oxygen in cells. However, it attracted the attention of researchers due its participation in free radical production in vivo, mainly through the production of superoxide radicals. In plants, XOR is a key enzyme in purine degradation where it catalyzes the oxidation of hypoxanthine to xanthine and of xanthine to uric acid. Both reactions are accompanied by electron transfer to either NAD+ with simultaneous formation of NADH or to molecular oxygen, which results in formation of superoxides. Characterization of plant XOR mutants and isolated XOR proteins from various plant species provided evidence that the enzyme plays significant roles in plant growth, leaf senescence, fruit size, synthesis of nitrogen storage compounds, and plant-pathogen interactions. Moreover, the ability of XOR to carry out redox reactions as NADH oxidase and to produce reactive oxygen species and nitric oxide, together with a possible complementary role in abscisic acid synthesis have raised further attention on the importance of this enzyme. Based on these established and proposed functions, XOR is discussed as regulator of different processes of interest in plant biology and agriculture.The authors acknowledge the support of the research grants AGL2010-16167 to J.F.M. from the Spanish Ministry of Science and Innovation and Bi 1075/5-1 to F.B. by the Deutsche Forschungsgemeinschaft. R.E. received a JAE-Doctor grant from the Spanish Research Council (CSIC).

‘The Insignia of Women’: Dress, Gender and identity on the Roman funerary monument of Regina from Arbeia

The current study focuses on the Roman gravestone of a British woman named Regina who died in the second half of the second century at the Roman fort of Arbeia (South Shields) at the mouth of the Tyne and was commemorated by her Palmyrene husband. The paper examines the Latin and Aramaic inscriptions on Regina's gravestone, the depiction of her ethnic clothing and bodily adornment, and the portrayal of the deceased as a woman skilled in wool-working, in order to contextualize and understand the important messages the monument conveys about physical mobility, ethnicity, social standing and gender relationships on Rome's northern frontier