The alteration in the architecture of a T‐DNA insertion rice mutant osmtd1 is caused by up‐regulation of MicroRNA156f

Plant architecture is an important factor for crop production. Some members of microRNA156 (miR156) and their target genes SQUAMOSA Promoter‐Binding Protein‐Like (SPL) were identified to play essential roles in the establishment of plant architecture. However, the roles and regulation of miR156 is not well understood yet. Here, we identified a T‐DNA insertion mutant Osmtd1 (Oryza sativa multi‐tillering and dwarf mutant). Osmtd1 produced more tillers and displayed short stature phenotype. We determined that the dramatic morphological changes were caused by a single T‐DNA insertion in Osmtd1. Further analysis revealed that the T‐DNA insertion was located in the gene Os08g34258 encoding a putative inhibitor I family protein. Os08g34258 was knocked out and OsmiR156f was significantly upregulated in Osmtd1. Overexpression of Os08g34258 in Osmtd1 complemented the defects of the mutant architecture, while overexpression of OsmiR156f in wild‐type rice phenocopied Osmtd1. We showed that the expression of OsSPL3, OsSPL12, and OsSPL14 were significantly downregulated in Osmtd1 or OsmiR156f overexpressed lines, indicating that OsSPL3, OsSPL12, and OsSPL14 were possibly direct target genes of OsmiR156f. Our results suggested that OsmiR156f controlled plant architecture by mediating plant stature and tiller outgrowth and may be regulated by an unknown protease inhibitor I family protein.     

Arabidopsis SMALL ORGAN 4, a homolog of yeast NOP53, regulates cell proliferation rate during organ growth

Cell proliferation is a fundamental event essential for plant organogenesis and contributes greatly to the final organ size. Although the control of cell proliferation in plants has been extensively studied, how the plant sets the cell number required for a single organ is largely elusive. Here, we describe the Arabidopsis SMALL ORGAN 4 (SMO4) that functions in the regulation of cell proliferation rate and thus final organ size. The smo4 mutant exhibits a reduced size of organs due to the decreased cell number, and further analysis reveals that such phenotype results from a retardation of the cell cycle progression during organ development. SMO4 encodes a homolog of NUCLEOLAR PROTEIN 53 (NOP53) in Saccharomyces cerevisiae and is expressed primarily in tissues undergoing cell proliferation. Nevertheless, further complementation tests show that SMO4 could not rescue the lethal defect of NOP53 mutant of S. cerevisiae. These results define SMO4 as an important regulator of cell proliferation during organ growth and suggest that SMO4 might have been evolutionarily divergent from NOP53.     

Glucose alleviates cadmium toxicity by increasing cadmium fixation in root cell wall and sequestration into vacuole in Arabidopsis

Glucose(Glu) is involved in not only plant physiological and developmental events but also plant responses to abiotic stresses. Here, we found that the exogenous Glu improved root and shoot growth, reduced shoot cadmium(Cd) concentration, and rescued Cdinduced chlorosis in Arabidopsis thaliana(Columbia ecotype,Col-0) under Cd stressed conditions. Glucose increased Cd retained in the roots, thus reducing its translocation from root to shoot signi fi cantly. The most Cd retained in the roots was found in the hemicellulose 1. Glucose combined with Cd(Glu t Cd) treatment did not affect the content of pectin and its binding capacity of Cd while it increased the content of hemicelluloses 1 and the amount of Cd retained in it signi fi cantly. Furthermore, Leadmium Green staining indicated that more Cd was compartmented into vacuoles in Glu t Cd treatment compared with Cd treatment alone, which was in accordance with the R e ssigni fi cant upregulation of the expression of tonoplastlocalized metal transporter genes, suggesting that compartmentation of Cd into vacuoles also contributes to the Glu-alleviated Cd toxicity. Taken together, we demonstrated that Glu-alleviated Cd toxicity is mediated through increasing Cd fi xation in the root cell wall and sequestration into the vacuoles.     

An eukaryotic translation initiation factor,AteIF5A‐2, affects cadmium accumulation and sensitivity in Arabidopsis

Cadmium (Cd) is one of the most toxic elements and can be accumulated in plants easily; meanwhile, eIF5A is a highly conserved protein in all eukaryotic organisms. The present work tried to investigate whether eIF5A is involved in Cd accumulation and sensitivity in Arabidopsis (Arabidopsis thaliana L.) by comparing the wild‐type Columbia‐0 (Col‐0) with a knockdown mutant of AteIF5A‐2, fbr12‐3 under Cd stress conditions. The results showed that the mutant fbr12‐3 accumulated more Cd in roots and shoots and had significantly lower chlorophyll content, shorter root length, and smaller biomass, suggesting that downregulation of AteIF5A‐2 makes the mutant more Cd sensitive. Real‐time polymerase chain reaction revealed that the expressions of metal transporters involved in Cd uptake and translocation including IRT1, ZIP1, AtNramp3, and AtHMA4 were significantly increased but the expressions of PCS1 and PCS2 related to Cd detoxification were decreased notably in fbr12‐3 compared with Col‐0. As a result, an increase in MDA and H₂O₂ content but decrease in root trolox, glutathione and proline content under Cd stress was observed, indicating that a severer oxidative stress occurs in the mutant. All these results demonstrated for the first time that AteIF5A influences Cd sensitivity by affecting Cd uptake, accumulation, and detoxification in Arabidopsis.     

Detoxification of insecticides,allechemicals and heavy metals by glutathione S‐transferase SlGSTE1 in the gut of Spodoptera litura

Insect glutathione S‐transferases (GSTs) play important roles in detoxifying toxic compounds and eliminating oxidative stress caused by these compounds. In this study, detoxification activity of the epsilon GST SlGSTE1 in Spodoptera litura was analyzed for several insecticides and heavy metals. SlGSTE1 was significantly up‐regulated by chlorpyrifos and xanthotoxin in the midgut of S. litura. The recombinant SlGSTE1 had V_max (reaction rate of the enzyme saturated with the substrate) and K_m (michaelis constant and equals to the substrate concentration at half of the maximum reaction rate of the enzyme) values of 27.95 ± 0.88 μmol/min/mg and 0.87 ± 0.028 mmol/L for glutathione, respectively, and V_max and K_m values of 22.96 ± 0.78 μmol/min/mg and 0.83 ± 0.106 mmol/L for 1‐chloro‐2,4‐dinitrobenzene, respectively. In vitro enzyme indirect activity assay showed that the recombinant SlGSTE1 possessed high binding activities to the insecticides chlorpyrifos, deltamethrin, malathion, phoxim and dichloro‐diphenyl‐trichloroethane (DDT). SlGSTE1 showed higher binding activity to toxic heavy metals cadmium, chromium and lead than copper and zinc that are required for insect normal growth. Western blot analysis showed that SlGSTE1 was induced in the gut of larvae fed with chlorpyrifos or cadmium. SlGSTE1 also showed high peroxidase activity. All the results together indicate that SlGSTE1 may play an important role in the gut of S. litura to protect the insect from the toxic effects of these compounds and heavy metals.     

高粱、紫苏叶脉密度与光合特性的关系

叶脉是植物叶片光合作用水分输送的重要结构。为阐述叶脉与光合特性之间的关系,以C4植物高粱(Sorghum bicolor)、C3植物紫苏(Perilla frutescens)为实验材料研究了叶脉密度和光合特性之间的关系。结果表明,与紫苏相比,高粱叶片叶脉密度大,导水能力强,蒸腾速率高,但气孔密度小。进一步分析表明,高粱叶片近轴侧气孔密度占总气孔的比例明显高于紫苏。叶脉密度大的高粱具有较高的净光合速率;而紫苏叶脉密度小,净光合速率也较低。由此表明,较高的叶脉密度有利于支持较高的光合速率,但研究表明叶脉密度和气孔密度可能不存在严格的协同变异关系。研究结果对理解植物光合作用适应有重要意义。     

Clinical,Virological and Immunological Features from Patients Infected with Re-Emergent Avian-Origin Human H7N9 Influenza Disease of Varying Severity in Guangdong Province

BackgroundThe second wave of avian influenza H7N9 virus outbreak in humans spread to the Guangdong province of China by August of 2013 and this virus is now endemic in poultry in this region.MethodsFive patients with H7N9 virus infection admitted to our hospital during August 2013 to February 2014 were intensively investigated. Viral load in the respiratory tract was determined by quantitative polymerase chain reaction (Q-PCR) and cytokine levels were measured by bead-based flow cytometery.ResultsFour patients survived and one died. Viral load in different clinical specimens was correlated with cytokine levels in plasma and broncho-alveolar fluid (BALF), therapeutic modalities used and clinical outcome. Intravenous zanamivir appeared to be better than peramivir as salvage therapy in patients who failed to respond to oseltamivir. Higher and more prolonged viral load was found in the sputum or endotracheal aspirates compared to throat swabs. Upregulation of proinflammatory cytokines IP-10, MCP-1, MIG, MIP-1α/β, IL-1β and IL-8 was found in the plasma and BALF samples. The levels of cytokines in the plasma and viral load were correlated with disease severity. Reactivation of herpes simplex virus type 1(HSV-1) was found in three out of five patients (60%).ConclusionExpectorated sputum or endotracheal aspirate specimens are preferable to throat swabs for detecting and monitoring H7N9 virus. Severity of the disease was correlated to the viral load in the respiratory tract as well as the extents of cytokinemia. Reactivation of HSV-1 may contribute to clinical outcome.     

Advancing Analysis of Spatio-Temporal Variations of Soil Nutrients in the Water Level Fluctuation Zone of China’s Three Gorges Reservoir Using Self-Organizing Map

The ~350 km² water level fluctuation zone (WLFZ) in the Three Gorges Reservoir (TGR) of China, situated at the intersection of terrestrial and aquatic ecosystems, experiences a great hydrological change with prolonged winter inundation. Soil samples were collected in 12 sites pre- (September 2008) and post submergence (June 2009) in the WLFZ and analyzed for soil nutrients. Self-organizing map (SOM) and statistical analysis including multi-way ANOVA, paired-T test, and stepwise least squares multiple regression were employed to determine the spatio-temporal variations of soil nutrients in relation to submergence, and their correlations with soil physical characteristics. Results showed significant spatial variability in nutrients along ~600 km long shoreline of the TGR before and after submergence. There were higher contents of organic matter, total nitrogen (TN), and nitrate (NO3-) in the lower reach and total phosphorus (TP) in the upper reach that were primarily due to the spatial variations in soil particle size composition and anthropogenic activities. Submergence enhanced soil available potassium (K), while significantly decreased soil N, possibly due to the alterations of soil particle size composition and increase in soil pH. In addition, SOM analysis determined important roles of soil pH value, bulk density, soil particle size (i.e., silt and sand) and nutrients (TP, TK, and AK) on the spatial and temporal variations in soil quality. Our results suggest that urban sewage and agricultural runoffs are primary pollutants that affect soil nutrients in the WLFZ of TGR.     

Olfactory Dysfunction and Neurotransmitter Disturbance in Olfactory Bulb of Transgenic Mice Expressing Human A53T Mutant α-Synuclein

Parkinson disease is a multi-system neurodegenerative disease characterized by both motor and non-motor symptoms. Hyposmia is one of the early non-motor symptoms occurring in more than 90% of Parkinson disease cases, which can precede motor symptoms even several years. Up to now, the relationship between hyposmia and Parkinson disease remains elusive. Lack of proper animal models of hyposmia restricts the investigation. In this study we assessed olfactory function in Prp-A53T-α-synuclein transgenic (αSyn^A53T) mice which had been reported to show age-dependent motor impairments and intracytoplasmic inclusions. We also examined cholinergic and dopaminergic systems in olfactory bulb of αSyn^A53T mice by immunofluorescent staining, enzyme linked immunosorbent assay and western blot. We found that compared to wild type littermates, αSyn^A53T mice at 6 months or older displayed a deficit of odor discrimination and odor detection. No significant changes were found in olfactory memory and odor habituation. Furthermore compared to wildtype littermates, in olfactory bulb of αSyn^A53T mice at 10 months old we detected a marked decrease of cholinergic neurons in mitral cell layer and a decrease of acetylcholinesterase activity, while dopaminergic neurons were found increased in glomerular layer, accompanied with an increase of tyrosine hydroxylase protein. Our studies indicate that αSyn^A53T mice have olfactory dysfunction before motor deficits occur, and the cholinergic and dopaminergic disturbance might be responsible for the Parkinson disease-related olfactory dysfunction.