A novel histidine kinase gene, ZmHK9, mediate drought tolerance through the regulation of stomatal development in Arabidopsis

Plants have developed complex signaling networks to regulate biochemical and physiological acclimation, environmental signals were perceived and transmitted to cellular machinery to activate adaptive responses. Here, a novel drought responsive histidine kinase gene was identified and designated as ZmHK9. Under normal conditions, ZmHK9 was predominantly expressed in roots, and the roots of ZmHK9-OX transgenic lines are markedly hypersensitive to ABA and ethylene, as compare to wild type. Consistent with its expression induced by PEG and exogenous ABA treatment, promoter sequence of this gene possessed drought and ABA responsive element. Moreover, the transgenic plants were much less affected by drought stress and recovered quickly after rewatering, stomatal complex size and stomatal density in the transgenic plants are significantly smaller and lower than those of the wild-type plants. In addition, ABA induced stomatal closure and the stomatal aperture of ZmHK9-OX lines was smaller than that of wild type. Collectively, it can be concluded that ZmHK9 regulates root elongation, stomatal development and drought tolerance through ABA dependent signaling pathway in Arabidopsis.     

Proteomic identification of predictive biomarkers of resistance to neoadjuvant chemotherapy in luminal breast cancer: a possible role for 14-3-3 theta/tau and tBID?

Introduction

Chemotherapy resistance is a major obstacle in effective neoadjuvant treatment for estrogen receptor-positive breast cancer. The ability to predict tumour response would allow chemotherapy administration to be directed towards only those patients who would benefit, thus maximising treatment efficiency. We aimed to identify putative protein biomarkers associated with chemotherapy resistance, using fresh tumour samples with antibody microarray analysis and then to perform pilot clinical validation experiments.

Materials and methods

Chemotherapy resistant and chemotherapy sensitive tumour samples were collected from breast cancer patients who had received anthracycline based neoadjuvant therapy consisting of epirubicin with cyclophosphamide followed by docetaxel. A total of 5 comparative proteomics experiments were performed using invasive ductal carcinomas which demonstrated estrogen receptor positivity (luminal subtype). Protein expression was compared between chemotherapy resistant and chemotherapy sensitive tumour samples using the Panorama XPRESS Profiler725 antibody microarray containing 725 antibodies from a wide variety of cell signalling and apoptosis pathways. A pilot series of archival samples was used for clinical validation of putative predictive biomarkers.

Results

AbMA analysis revealed 38 differentially expressed proteins which demonstrated at least 1.8 fold difference in expression in chemotherapy resistant tumours and 7 of these proteins (Zyxin, 14-3-3 theta/tau, tBID, Pinin, Bcl-xL, RIP and MyD88) were found in at least 2 experiments. Clinical validation in a pilot series of archival samples revealed 14-3-3 theta/tau and tBID to be significantly associated with chemotherapy resistance.

Conclusions

For the first time, antibody microarrays have been used to identify proteins associated with chemotherapy resistance using fresh breast cancer tissue. We propose a potential role for 14-3-3 theta/tau and tBID as predictive biomarkers of neoadjuvant chemotherapy resistance in breast cancer. Further validation in a larger sample series is now required.     

CO2‐caused change in plant species composition rivals the shift in vegetation between mid‐grass and tallgrass prairies

Atmospheric CO₂ enrichment usually changes the relative contributions of plant species to biomass production of grasslands, but the types of species favored and mechanisms by which change is mediated differ among ecosystems. We measured changes in the contributions of C₃ perennial forbs and C₄ grasses to aboveground biomass production of tallgrass prairie assemblages grown along a field CO₂ gradient (250–500 μmol mol^?1) in central Texas USA. Vegetation was grown on three soil types and irrigated each season with water equivalent to the growing season mean of precipitation for the area. We predicted that CO₂ enrichment would increase the forb contribution to community production, and favor tall‐grasses over mid‐grasses by increasing soil water content and reducing the frequency with which soil water fell below a limitation threshold. CO₂ enrichment favored forbs over grasses on only one of three soil types, a Mollisol. The grass fraction of production increased dramatically across the CO₂ gradient on all soils. Contribution of the tall‐grass Sorghastrum nutans to production increased at elevated CO₂ on the two most coarse‐textured of the soils studied, a clay Mollisol and sandy Alfisol. The CO₂‐caused increase in Sorghastrum was accompanied by an offsetting decline in production of the mid‐grass Bouteloua curtipendula. Increased CO₂ favored the tall‐grass over mid‐grass by increasing soil water content and apparently intensifying competition for light or other resources (Mollisol) or reducing the frequency with which soil water dipped below threshold levels (Alfisol). An increase in CO₂ of 250 μmol mol^?1 above the pre‐industrial level thus led to a shift in the relative production of established species that is similar in magnitude to differences observed between mid‐grass and tallgrass prairies along a precipitation gradient in the central USA. By reducing water limitation to plants, atmospheric CO₂ enrichment may alter the composition and even structure of grassland vegetation.     

Satellite surface reflectance improves habitat distribution mapping: a case study on heath and shrub formations in the Cantabrian Mountains (NW Spain)

Aim We aim to map the distribution of four heath and shrub formations constituting habitats of high conservation priority in Europe, whose occurrence is strongly dependent on human activities. Specifically, we assess whether the use of LANDSAT data in habitat distribution modelling may account for land use management, allowing accurate mapping of real distribution patterns. In particular, we explore whether reflectance values may be a better alternative to other remote sensing data traditionally used in modelling approaches (i.e. spectral vegetation indices and classified land cover maps). Finally, we test whether modelling performance is affected by the ecological traits of the dominant species of the target formations. Location Cantabrian Mountains (NW Spain). Methods We generated maps for the four formations (two specialists vs. two generalists) using MaxEnt. First, we ran the models with environmental predictors only (topography, climate, lithology and human disturbances). Then, we compared the advantages of including, in turn, different data derived from LANDSAT imagery: reflectance values (corresponding to different wavelength channels of the multispectral image), a spectral index and a land cover map. We assessed changes in explanatory power and also in the formation’s predicted distribution patterns. Results Formations dominated by specialist species were accurately mapped on a base of environmental variables only, whereas those dominated by generalists were overpredicted. Average mean temperature, southness and distance to urban areas were the variables contributing most in predictions of environmental models. LANDSAT channels increased the accuracy of all models, but mainly those for formations dominated by generalist species. They showed advantages against other remote sensing data traditionally used in modelling approaches. Main conclusions Habitat distribution models allowed accurate mapping of heath and shrub formations. The use of reflectance values as predictors improved the accuracy of the models, particularly for formations dominated by generalist species, supplying environmental information that was otherwise unavailable.     

内耳形态学和生理指标对缺铁性肾虚耳聋大鼠模型的评价作用

目的探讨耳蜗显微结构和生理指标对缺铁性肾虚耳聋大鼠模型的评价作用。方法选用体重30～32 g、无耳疾、听性脑干反应(auditory brainstem response,ABR)阈值正常的1～2周龄SPF级SD大鼠120只,雌雄分养,分为缺铁组80只、正常对照组40只,饲养时间12周;以出现肾虚证和至少一耳ABR阈值≥15 dB,作为判断肾虚耳聋的标准,获得缺铁性肾虚耳聋大鼠22只,从中选取肾虚耳聋大鼠20只,同时以20只正常大鼠作对照。观察耳蜗血管纹、螺旋器等耳蜗显微结构变化,检测ABR阈值以及血红蛋白和血清铁等指标的变化。结果实验组和正常对照大鼠的血红蛋白和血清铁分别为11.80 g/L,4.5μmol/L和45.9 g/L,22.23μmol/L,ABR阈值分别为(30±5)dB和(10±5)dB;实验组血管纹血管明显减少;螺旋器毛细胞听毛有缺失、倒伏现象。结论缺铁性肾虚耳聋大鼠血红蛋白、血清铁和ABR阈值,以及耳蜗血管纹、螺旋器等耳蜗显微结构变化等指标,均较为稳定,是较好的评价指标。     

Genetic variation underlying the expression of a polyphenism

Polyphenic traits are widespread and represent a conditional strategy sensitive to environmental cues. The environmentally cued threshold (ET) model considers the switchpoint between alternative phenotypes as a polygenic quantitative trait with normally distributed variation. However, the genetic variation for switchpoints has rarely been explored empirically. Here, we used inbred lines to investigate the genetic variation for the switchpoint in the mite Rhizoglyphus echinopus, in which males are either fighters or scramblers. The conditionality of male dimorphism varied among inbred lines, indicating that there was genetic variation for switchpoints in the base population, as predicted by the ET model. Our results also suggest a mixture between canalized and conditional strategists in R. echinopus. We propose that major genes that canalize morph expression and affect the extent to which a trait can be conditionally expressed could be a feature of the genetic architecture of threshold traits in other taxa.     

心肌造影负荷超声心动图评价存活心肌的临床研究

目的:研究心肌造影负荷超声心动图(MCSE)定量心肌血流判断存活心肌的可行性与可靠性。方法:对20例冠心病患者行持续静脉滴注法MCSE,按1:4的比例于收缩末期触发的方式提取图像,采集图像后脱机分析及彩色编码。计算灌注正常区域和灌注缺损区域的A.β值,根据A.β值确定心肌存活与否,将判定结果正电子断层显像(PET)进行对照。结果:17例病人(85%)获得满意图像,灌注正常区和灌注缺损区的A.β值分别为59.32±11.54和5.69±1.78;灌注正常区在Dob 5μg、10μg时的A.β均值分别为69.57±8.13和76.65±13.61,且均高于静息时A.β值,与PET判定坏死的心肌节段一致。结论:MCSE能从血流定量水平判断存活心肌。