Effect of Increasing CO_2 on the Stratospheric Level of CO and O_3

Production and destruction processes of carbon monoxide (CO) and ozone (O3) are examined in the light of increasing amount of atmospheric carbon dioxide (CO2). It is found that doubling of CO2 will increase the stratospheric concentration of CO and will have positive effect on O3 concentration.

OTS_1-dependent deSUMOylation increases tolerance to high copper levels in Arabidopsis

The conjugation of SUMO （small ubiquitin-like modifier） to protein substrates is a reversible process （SUMOylation/deSUMOylation） that regulates plant devel- opment and stress responses. The essential metal copper （Cu） is required for normal plant growth, but excess amounts are toxic. The SUMO E3 ligase, SIZI, and SIZ1- mediated SUMOylation function in plant tolerance to excess Cu. It is unknown whether deSUMOylation also contributes to Cu tolerance in plants. Here, we report that OTSI, a protease that cleaves SUMO from its substrate proteins, participates in Cu tolerance in Arabidopsis thaliana （Arabi- dopsis）. OTS1 loss-of-function mutants （otsl-2 and otsl-3） displayed increased sensitivity to excess Cu. Redox homeostasis and the balance between SUMOylation and deSUMOylation were disrupted in the otsl-3 mutant under excess Cu conditions, The otsl-3 mutant accumulated higher levels of Cu in both shoots and roots compared to wild type. Specific Cu-related metal transporter genes were upregu- lated due to the loss-of-function of OTS% which might explain the high Cu levels in otsl-3. These results suggest that the SUMOylation/deSUMOylation machinery is acti- vated in response to excess Cu, and modulates Cu homeostasis and tolerance by regulating both Cu uptake and detoxification. Together, our findings provide insight into the biological function and regulatory role of SUMOylation/deSUMOylation in plant tolerance to Cu.

Recent advances in enhancing reactive oxygen species based chemodynamic therapy

Chemodynamic therapy(CDT),defined as an in situ oxidative stress response catalyzed by the Fenton or Fenton-like reactions to generate cytotoxic hydroxyl radicals(•OH)at tumor sites,exhibits conspicuous inhibition of tumor growth.It has attracted extensive attention for its outstanding edge in effectiveness,lower systemic toxicity and side effects,sustainability,low cost and convenience.However,the inconfor-mity of harsh Fenton reaction conditions and tumor microenvironment hamper its further development,based on which,numerous researchers have made efforts in further improving the efficiency of CDT.In this review,we expounded antitumor capacity of CDT in mechanism,together with its limitation,and then summarized and came up with several strategies to enhance CDT involved tumor therapy strategies by 1)improving catalytic efficiency;2)increasing hydrogen peroxide levels at tumor sites;3)reducing glutathione levels at tumor sites;4)applying external energy intervention;5)amplifying the distribu-tion of hydroxyl radicals at tumor sites;and 6)combination therapy.Eventually,the perspectives and challenges of CDT are further discussed to encourage more in-depth studies and rational reflections.