[Responses of photosynthetic characteristics in leaves of Physocarpus amurensis and P opulifolius to drought stress]. / ä¹¡åœŸé£Žç®±æžœå’Œç´«å¶é£Žç®±æžœå¶ç‰‡å ‰åˆç‰¹æ€§å¯¹åœŸå£¤å¹²æ—±çš„å“åº”.

This experiment was conducted to study the responses of photosynthetic gas exchange parameters and the chlorophyll fluorescence parameters in leaves to soil drought. Furthermore, the drought resistance abilities of the endangered native Physocarpus amurensis and the introduced P. opulifolius as well as their differences were studied. The results showed that the leaves of P. opulifolius wilted significantly, while the leaf water content and water use efficiency of the native P. amurensis were higher on the 7th day after soil drought. Soil drought reduced the net photosynthetic rate, stomatal conductance, and transpiration rate in the leaves of the two Physocarpus species, while the observed decrease of P. opulifolius was significantly higher than that of P. amurensis. On the 7th day after soil drought, the intercellular CO2 concentration (Ci) of P. opulifolius was higher than that without drought treatment, while the Ci of P. amurensis was lower than that without drought treatment. The electron transfer rate (ETR) and photochemical quenching coefficient (qP) in leaves of P. amurensis were clearly decreased, while differences of the light energy capture efficiency (Fv'/Fm') in the PS2 reaction center were non-significant. However, Fv'/Fm', ETR, and qP in the lea-ves of P. opulifolius were all significantly decreased to greater extents compared to those in P. amurensis. On the 7th day after soil drought, a non-significant change was observed on the relative variable fluorescence (VJ) at site J of the OJIP curve of P. amurensis leaves, while VJ in leaves of P. opuli-folius was increased. The carbon assimilation ability of P. opulifolius leaves and the sensibility of PS2 function to soil drought were significantly higher than those of P. amurensis. The reduction in the photosynthetic capacity induced by soil drought was mainly due to the limitation of the stomatal factors for P. amurensis, but mainly due to the limitation of the non-stomatal factors for P. opulifolius.

Let-7 inhibits self-renewal of hepatocellular cancer stem-like cells through regulating the epithelial-mesenchymal transition and the Wnt signaling pathway.

BACKGROUND: Tumor suppressive let-7 miRNAs are universally down-regulated in human hepatocellular carcinoma (HCC) versus normal tissues; however, the roles and related molecular mechanisms of let-7 in HCC stem cells are poorly understood. METHODS: We examined the inhibitory effect of let-7 miRNAs on the proliferation of MHCC97-H and HCCLM3 hepatic cancer cells by using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, which was further confirmed by apoptosis and cell cycle studies. The sphere-forming assay was used to study the effects of let-7a on stem like cells. Through western blot, immunofluorescence and the luciferase-reporter assay, we explored the activity of epithelial-mesenchymal transition (EMT) signaling factors in HCC cells. qRT-PCR was applied to detect miRNA expression levels in clinical tissues. RESULTS: Let-7a effectively repressed cell proliferation and viability, and in stem-like cells, also let-7a decreased the efficiency of sphere formation.in stem-like cells. The suppression of EMT signaling factors in HCC cells contributed to let-7's induced tumor viability repression and Wnt activation repression. Besides, Wnt1 is critical and essential for let-7a functions, and the rescue with recombinant Wnt1 agent abolished the suppressive roles of let-7a on hepatospheres. In clinical HCC and normal tissues, let-7a expression was inversely correlated with Wnt1 expression. CONCLUSIONS: Let-7 miRNAs, especially let-7a, will be a promising therapeutic strategy in the treatment of HCC through eliminating HCC stem cells, which could be achieved by their inhibitory effect on the Wnt signaling pathway.