Actin bundler PLIM2s are involved in the regulation of pollen development and tube growth in Arabidopsis

Microspores develop inside the anther, where they are surrounded by nourishing tapetal cells. However, many cellular processes occurring during microspore development in the locule are poorly characterized. The actin cytoskeleton is known to play a crucial role in various aspects of the plant developmental process. During pollen tube tip growth, actin cytoskeleton serves as an efficient molecular transportation track, although how it functions in pollen development is unknown. The plant actin bundler PLIM2s have been shown to regulate actin bundling in different cells. Here, we investigate the biological function of three Arabidopsis pollen-specific LIM proteins, PLIM2a, PLIM2b, and PLIM2c (collectively, PLIM2s), in pollen development and tube growth. Variable degrees of suppressed expression of the PLIM2s by RNA interference resulted in aberrant phenotypes. Complete suppression of the PLIM2s totally disrupted pollen development, producing abortive pollen grains and rendering the transgenic plants sterile. Partial suppression of the PLIM2s arrested pollen tube growth to a lesser extent, resulting in short and swollen pollen tubes. Finally, the PLIM2c promoter initiated expression in pollen during stamen filament elongation, and the PLIM2c protein was located on particle structures in the developing pollen grains in Arabidopsis. These suggest that the actin bundler, PLIM2s, are an important factor for Arabidopsis pollen development and tube growth.     

Local genetic structure in the critically endangered,cave‐associated perennial herb Primulina tabacum (Gesneriaceae)

The local spatial genetic structures of cave‐associated plants are seldom studied. Given that these plants are mainly confined to small areas in and around the entrances of caves, we hypothesized that they might lack genetic structures at local scales. To test this hypothesis, we sampled two large populations (named D and T) of a critically endangered perennial herb, Primulina tabacum, which is endemic to karst caves in southern China. We analysed nine microsatellite loci and sequenced four chloroplast DNA (cpDNA) intergenic spacer regions to study the genetic diversity and structure within and between both populations. Both populations have distinct genetic characteristics. Samples from two subpopulations in population D showed considerable genetic divergence. This is not consistent with the hypothesis that P. tabacum has a weak genetic structure at a local scale. However, 94% of the individuals in population T shared the same multilocus genotype, which indicates little genetic structure within this population. The contributions of seed flow, pollen flow and (sub)population history to the genetic diversity and structure in each and both populations are discussed. Our study is the first to investigate local genetic diversity and structure in a cave‐associated plant, and provides valuable information for the sustainable conservation of such species. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 747–756.     

Serum proteomic profiling for the early diagnosis of colorectal cancer

No ideal serum biomarker currently exists for the early diagnosis of colorectal cancer (CRC). Magnetic bead‐based fractionation coupled with MALDI‐TOF MS was used to screen serum samples from CRC patients, healthy controls, and other cancer patients. A diagnostic model with five proteomic features (m/z 1778.97, 1866.16, 1934.65, 2022.46, and 4588.53) was generated using Fisher algorithm with best performance. The Fisher‐based model could discriminate CRC patients from the controls with 100% (46/46) sensitivity and 100% (35/35) specificity in the training set, 95.6% (43/45) sensitivity and 83.3% (35/42) specificity in the test set. We further validated the model with 94.4% (254/269) sensitivity and 75.5% (83/110) specificity in the external independent group. In other cancers group, the Fisher‐based model classified 25 of 46 samples (54.3%) as positive and the other 21 as negative. With FT‐ICR‐MS, the proteomic features of m/z 1778.97, 1866.16, 1934.65, and 2022.46, of which intensities decreased significantly in CRC, were identified as fragments of complement C3f. Therefore, the Fisher‐based model containing five proteomic features was able to effectively differentiate CRC patients from healthy controls and other cancers with a high sensitivity and specificity, and may be CRC‐specific. Serum complement C3f, which was significantly decreased in CRC group, may be relevant to the incidence of CRC. J. Cell. Biochem. 114: 448–455, 2013. © 2012 Wiley Periodicals, Inc.     

On computation of semiparametric maximum likelihood estimators with shape constraints

Large sample theory of semiparametric models based on maximum likelihood estimation (MLE) with shape constraint on the nonparametric component is well studied. Relatively less attention has been paid to the computational aspect of semiparametric MLE. The computation of semiparametric MLE based on existing approaches such as the expectation‐maximization (EM) algorithm can be computationally prohibitive when the missing rate is high. In this paper, we propose a computational framework for semiparametric MLE based on an inexact block coordinate ascent (BCA) algorithm. We show theoretically that the proposed algorithm converges. This computational framework can be applied to a wide range of data with different structures, such as panel count data, interval‐censored data, and degradation data, among others. Simulation studies demonstrate favorable performance compared with existing algorithms in terms of accuracy and speed. Two data sets are used to illustrate the proposed computational method. We further implement the proposed computational method in R package BCA1SG , available at CRAN.     

胆固醇结晶激活动脉粥样硬化斑块巨噬细胞NLRP3炎症体的途径

动脉粥样硬化既是胆固醇在血管壁聚集的疾病,也是发生在动脉壁的一种低强度慢性炎症形式。近年来有研究证实胆固醇结晶在动脉粥样硬化发生发展中具有重要作用。新的显微技术证实,胆固醇结晶在动脉粥样硬化斑块形成的早期即已出现,并与早期炎症有关。胆固醇结晶通过诱发局部炎症,促进大的脂质核心形成;刺破纤维帽,导致斑块破裂进而促进动脉粥样硬化斑块的进展。在影响斑块进程中,NLRP3炎症体的激活对此发挥了重要的作用。NLRP3炎症体是研究最多最明确的炎症体,其与非炎症性疾病的发生发展密切相关。以胆固醇结晶激活NLRP3炎症体的途径作为研究靶点,为动脉粥样硬化的诊断和治疗提供了新的思路和方法。该文就胆固醇结晶在动脉粥样硬化斑块中激活巨噬细胞NLRP3炎症体的两种途径做一综述。     

Metal Halide Perovskite Materials for Solar Cells with Long‐Term Stability

Metal halide perovskite solar cells (PSCs) have emerged as promising candidates for photovoltaic technology with their power conversion efficiencies over 23%. For prototypical organic–inorganic metal halide perovskites, their intrinsic instability poses significant challenges to the commercialization of PSCs. Recently, the scientific community has done tremendous work in composition engineering to develop more robust light‐absorbing layers, including mixed‐ion hybrid perovskites, low‐dimensional hybrid perovskites, and all‐inorganic perovskites. This review provides an overview of the impact of these perovskites on the efficiency and long‐term stability of PSCs.     

不同功能区城市林业土壤黑碳含量及来源——以南京市为例

由于城市化过程中人为活动的影响,城市林业土壤的性质发生了很大变化。城市林业土壤黑碳由于来源的多样性和受到人为活动的影响,其分布表现出独特的特征。以南京市为对象,调查分析了不同功能区城市林业土壤黑碳的含量及可能来源。结果表明:不同功能区城市林业土壤黑碳含量差异很大,其变幅为0.77-21.27g/kg。道路绿化带土壤黑碳含量显著高于其它功能区,居民区含量最低。黑碳在土壤表层中含量均高于表下层,黑碳富集于土壤表层。道路绿化带表层土壤黑碳含量与有机碳含量的比值(BC/SOC)为0.55,土壤黑碳的碳同位素比值(δ¹³C_PDB)为-27.04‰,与其它功能区差异显著,城市交通污染对土壤黑碳积累产生强烈影响。