Fangxiu Xu

Photosynthetic and respiratory exchanges of CO(2) by plants with the atmosphere are significantly larger than anthropogenic CO(2) emissions, and these fluxes will change as growing conditions are altered by climate change. Understanding feedbacks in CO(2) exchange is important to predicting future atmospheric [CO(2)] and climate change. At the tissue and plant scale, respiration is a key determinant of growth and yield. Although the stimulation of C(3) photosynthesis by growth at elevated [CO(2)] can be predicted with confidence, the nature of changes in respiration is less certain. This is largely because the mechanism of the respiratory response is insufficiently understood. Molecular, biochemical and physiological changes in the carbon metabolism of soybean in a free-air CO(2) enrichment experiment were investigated over 2 growing seasons. Growth of soybean at elevated [CO(2)] (550 micromol x mol(-1)) under field conditions stimulated the rate of nighttime respiration by 37%. Greater respiratory capacity was driven by greater abundance of transcripts encoding enzymes throughout the respiratory pathway, which would be needed for the greater number of mitochondria that have been observed in the leaves of plants grown at elevated [CO(2)]. Greater respiratory quotient and leaf carbohydrate content at elevated [CO(2)] indicate that stimulated respiration was supported by the additional carbohydrate available from enhanced photosynthesis at elevated [CO(2)]. If this response is consistent across many species, the future stimulation of net primary productivity could be reduced significantly. Greater foliar respiration at elevated [CO(2)] will reduce plant carbon balance, but could facilitate greater yields through enhanced photoassimilate export to sink tissues.

// Ben Liu 1, * , Jinli Qu 1, * , Fangxiu Xu 1 , Yan Guo 1 , Yu Wang 1 , Herbert Yu 2 , Biyun Qian 1, 3 1 Department of Epidemiology and Biostatistics, Key Laboratory of Breast Cancer Prevention and Therapy, Ministry of Education, Key Laboratory of Cancer Prevention and Therapy, Tianjin, National Clinical Research Center of Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin 300060, China 2 Cancer Epidemiology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA 3 Hongqiao International Institute of Medicine, Shanghai Tongren Hospital and Faculty of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China * These authors have contributed equally to this work Correspondence to: Biyun Qian, e-mail: qianbiyun@shsmu.edu.cn Keywords: non-small cell lung cancer, miR -195, CHEK1, prognosis, cell cycle Received: December 08, 2014      Accepted: January 31, 2015      Published: March 25, 2015 ABSTRACT MiR-195 suppresses tumor growth and is associated with better survival outcomes in several malignancies including non-small cell lung cancer (NSCLC). Our previous study showed high miR-195 plasma levels associated with favorable overall survival of non-smoking women with lung adenocarcinoma. To further elucidate role of miR-195 in NSCLC, we conducted in vitro experiment as well as clinical studies in a cohort of 299 NSCLC samples. We demonstrated that miR-195 expression was lower in tumor tissues and was associated with poor survival outcome. Overexpression of miR-195 suppressed tumor cell growth, migration and invasion. We discovered that CHEK1 was a direct target of miR-195, which decreased CHEK1 expression in lung cancer cells. High expression of CHEK1 in lung tumors was associated with poor overall survival. Our results suggest that miR-195 suppresses NSCLC and predicts lung cancer prognosis.

Here we show that the expression of a cysteine proteinase coincides with several developmental events associated with programmed cell death (PCD) in Solanum melongena (brinjal), i.e. during leaf senescence, fruit senescence, xylogenesis, nucellar cell degeneration and anther senescence. We have isolated a cDNA encoding brinjal cysteine proteinase (SmCP) that shares high (90-92%) amino acid identity to cysteine proteinases of tobacco (CYP-8) and tomato (LCYP-2) that have not been previously reported to be senescence-associated. In contrast, SmCP shows lower (39-41%) amino acid identity to other senescence-related cysteine proteinases and, unlike most of them, it is not preferentially expressed in certain organs or cell types. Northern analysis of leaves, fruits and flowers at different stages of development showed that SmCP expression increased significantly at senescence in leaf and fruit, but was highly expressed throughout flower development. In situ hybridization studies on flower sections using an antisense RNA probe localized the SmCP mRNA to the xylem, the epidermis and the endothecium of the anther and the nucellar cells, suggesting its involvement in PCD during xylogenesis, anther senescence and ovule development, respectively. Its expression during nucellar cell degeneration suggests that protein reserves of the nucellus are released to the developing embryo. Polarity in its pattern of expression in the nucellus of the developing seed (40DAP) further implies a directional flow of these nutrients.

Antioxidant metabolism is responsive to environmental conditions, and is proposed to be a key component of ozone (O(3)) tolerance in plants. Tropospheric O(3) concentration ([O(3)]) has doubled since the Industrial Revolution and will increase further if precursor emissions rise as expected over this century. Additionally, atmospheric CO(2) concentration ([CO(2)]) is increasing at an unprecedented rate and will surpass 550 ppm by 2050. This study investigated the molecular, biochemical and physiological changes in soybean exposed to elevated [O(3) ] in a background of ambient [CO(2)] and elevated [CO(2)] in the field. Previously, it has been difficult to demonstrate any link between antioxidant defences and O(3) stress under field conditions. However, this study used principle components analysis to separate variability in [O(3)] from variability in other environmental conditions (temperature, light and relative humidity). Subsequent analysis of covariance determined that soybean antioxidant metabolism increased with increasing [O(3)], in both ambient and elevated [CO(2)]. The transcriptional response was dampened at elevated [CO(2)], consistent with lower stomatal conductance and lower O(3) flux into leaves. Energetically expensive increases in antioxidant metabolism and tetrapyrrole synthesis at elevated [O(3)] were associated with greater transcript levels of enzymes involved in respiratory metabolism.