Differential Responses of Water Uptake Pathways and Expression of Two Aquaporin Genes to Water-Deficit in Rice Seedlings of Two Genotypes

Water-deficit （WD） is a major abiotic stress constraining crop productivity worldwide. Zhenshan 97 is a drought-susceptible rice genotype, while IRAT109 is a drought-resistant one. However, the physiological basis of the difference remains unclear. These two genotypes had similar total water uptake rates under both WD and well-watered （WW） conditions, and their water uptake rates under WD were significantly decreased compared with those under WW. However, the water uptake rate via the cell-to-cell pathway was significantly increased in Zhenshan 97 but decreased in IRAT109 under WD, whereas the opposite trends were observed through the apoplastic pathway. These results indicated that the stress responses and relative contributions of these two water uptake pathways were associated with rice genotype under WD. The expression levels of OsPIP2;4 and OsPIP2;5 genes were significantly higher in roots of Zhenshan 97 than in IRAT109 under the two conditions. OsPIP2;4 expression in roots was significantly up-regulated under WD, while OsPIP2;5 expression showed no significant change. These results suggest that the expression levels of OsPIP2;4 and OsPIP2;5 in rice are dependent on genotype and water availability. Compared with Zhenshan 97, IRAT109 had a higher root dry weight, water uptake rate and xylem sap flow rate, and lower leaf water potential and root porosity under WD, which might be responsible for the drought resistance in IRAT109.

Berberine Relieves Insulin Resistance via the Cholinergic Anti-inflammatory Pathway in HepG2 Cells

Berberine（BBR） is an isoquinoline alkaloid extracted from Rhizoma coptidis and has been used for treating type 2 diabetes mellitus（T2DM） in China. The development of T2 DM is often associated with insulin resistance and impaired glucose uptake in peripheral tissues. In this study, we examined whether BBR attenuated glucose uptake dysfunction through the cholinergic anti-inflammatory pathway in Hep G2 cells. Cellular glucose uptake, quantified by the 2-[N-（7-Nitrobenz-2-oxa-1,3-diazol-4-yl）-amino]-2-deoxy-D-glucose（2-NBDG）, was inhibited by 21% after Hep G2 cells were incubated with insulin（10-6 mol/L） for 36 h. Meanwhile, the expression of alpha7 nicotinic acetylcholine receptor（α7n ACh R） protein was reduced without the change of acetylcholinesterase（ACh E） activity. The level of interleukin-6（IL-6） in the culture supernatant, the ratio of phosphorylated I-kappa-B kinase-β（IKKβ） Ser181/IKKβ and the expression of nuclear factor-kappa B（NF-κB） p65 protein were also increased. However, the treatment with BBR enhanced the glucose uptake, increased the expression of α7n ACh R protein and inhibited ACh E activity. These changes were also accompanied with the decrease of the ratio of p IKKβ Ser181/IKKβ, NF-κB p65 expression and IL-6 level. Taken together, these results suggest that BBR could enhance glucose uptake, and relieve insulin resistance and inflammation in Hep G2 cells. The mechanism may be related to the cholinergic anti-inflammatory pathway and the inhibition of ACh E activity.

Cadmium found in peanut (Arachis hypogaea L.) kernels mainly originates from root uptake rather than shell absorption from soil

Roots and shells are two potential organs through which peanut plants absorb cadium(Cd)from soils;however,the relative contributions of the two uptake pathways(root uptake and shell absorption)to kernel Cd accumulation and their translocation characteristics are poorly understood.In this study,the relative contributions of the two pathways to Cd accumulation in two peanut cultivars,Xianghua2008(XH)and Yueyou43(YY),were accurately assessed by labeling rooting and podding zone soils with 113Cd and 111Cd isotopes(0.3 mg kg^(-1) dry soil),respectively,in a split-pot design.The results showed that approximately 96%of the Cd accumulated in the peanut kernels was derived from root uptake,while only 4%originated from shell absorption.Only 1%of the Cd accumulated in whole peanut plants was attributed to shell absorption,of which 41%–44%was retained in shells and 56%–59%was translocated to kernels.In contrast,the Cd absorbed by roots was efficiently translocated into all plant organs,of which 80%–84%was distributed in shoots.Although YY accumulated 1.3 times more Cd in whole plants than XH,the relative contributions of the two pathways to Cd accumulation in each plant organ were barely affected by peanut cultivars.Due to the strong retention effect of shells,shell-derived Cd was approximately 2 times higher than root-derived Cd in shells.These results would improve the understanding of Cd accumulation processes in peanut plants,revealing that the root uptake pathway contributes predominantly to the Cd concentration in peanut kernels,based on which strategies and technology for the reduction of Cd in peanut plants could be designed and developed.

Graphene quantum dots: From efficient preparation to safe renal excretion

Carbon nanomaterials offer excellent prospects as therapeutic agents,and among them,graphene quantum dots(GQDs)have gained considerable interest thanks to their aqueous solubility and intrinsic fluorescence,which enable their possible use in theranostic approaches,if their biocompatibility and favorable pharmacokinetic are confirmed.We prepared ultra-small GQDs using an alternative,reproducible,top-down synthesis starting from graphene oxide with a nearly 100%conversion.The materials were tested to assess their safety,demonstrating good biocompatibility and ability in passing the ultrafiltration barrier using an in vitro model.This leads to renal excretion without affecting the kidneys.Moreover,we studied the GQDs in vivo biodistribution confirming their efficient renal clearance,and we demonstrated that the internalization mechanism into podocytes is caveolae-mediated.Therefore,considering the reported characteristics,it appears possible to vehiculate compounds to kidneys by means of GQDs,overcoming problems related to lysosomal degradation.