玉米对渗透胁迫的反应和生理适应

利用不同渗透势的培养液模拟土壤干旱条件,研究了玉米杂交种“中单2号”在此条件下的生长和生理的变化。实验表明,各指标对于渗透胁迫的变化敏感性顺序为叶片延伸速率、叶水势、脯氨酸含量>净光合速率>相对透性。玉米幼苗在渗透胁迫下具有一定的生理适应能力,表现在一定的渗透胁迫范围内随胁迫时间的延长,生长、生理变化有趋于缓和或恢复的趋势。     

Simultaneous Detection of Fenitrothion and Chlorpyrifos-Methyl with a Photonic Suspension Array

A technique was developed for simultaneous detection of fenitrothion (FNT) and chlorpyrifos-methyl (CLT) using a photonic suspension array based on silica colloidal crystal beads (SCCBs). The SCCBs were encoded with the characteristic reflection peak originating from the stop-band of colloidal crystal. This approach avoids the bleaching, fading or potential interference seen when encoding by fluorescence. SCCBs with a nanopatterned surface had increased biomolecule binding capacity and improved stability. Under optimal conditions, the proposed suspension array allowed simultaneous detection of the selected pesticides in the ranges of 0.25 to 1024 ng/mL and 0.40 to 735.37 ng/mL, with the limits of detection (LODs) of 0.25 and 0.40 ng/mL, respectively. The suspension array was specific and had no significant cross-reactivity with other chemicals. The mean recoveries in tests in which samples were spiked with target standards were 82.35% to 109.90% with a standard deviation within 9.93% for CLT and 81.64% to 108.10% with a standard deviation within 8.82% for FNT. The proposed method shows a potentially powerful capability for fast quantitative analysis of pesticide residues.     

山西绵山植被优势种群的分布格局与种间联结的研究

本文用方差/平均数比率的方法和通过2×2列联表进行X~2检验的方法,研究了山西绵山植被优势种的分布格局及种间联结性。结果表明:绵山优势种都服从集群分布;种间的正联结是物种对同质生境有相同适应性的反应;种问的负联结则是不同物种对异质生境适应性不同所致。在用X~2检验研究物种联结性的同时,用点相关系数来刻划种间的联结性强度,作为对种间联结的辅助说明是完全必要的。通过对种间联结的分析,还可以看出绵山植被的动态演替趋势。     

Quantitative Measurement of <Emphasis Type="Italic">PARD3</Emphasis> Copy Number Variations in Human Neural Tube Defects

Although more than 200 genes are known to be related to neural tube defects (NTDs), the exact molecular basis is still unclear. Evaluating the contribution of copy number variation (CNV) might be a priority because CNV involves changes in the copy number of large segments of DNA, leading to phenotypic traits and disease susceptibility. Recent studies have documented that the polarity protein partitioning defective 3 homolog (Pard3) plays an essential role in the process of neural tube closure. The aim of this study was to assess the role of PARD3 CNVs in the etiology of human NTDs. Relative quantitative PCR and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were used to quantitative measurement of CNVs in 25 PARD3 exons in 202 NTD cases and 231 controls from a region of China with a high prevalence of NTDs. The results showed that microduplications ranging from 3 to 4 were evident in coding Exon 21 and Exon 25 in both case and control groups. A novel heterozygous microdeletion spanning 444 bp of Exon 14 was identified in two cases of anencephaly and is absent from all controls analyzed. Expression analyses indicated that this heterozygotic microdeletion showed no tissue specificity and led to defective expression of PARD3. Our study provides further evidence implicating PARD3 in the etiology of NTDs.     

Biomass carbon storages and carbon sequestration potentials of the Grain for Green Program‐Covered Forests in China

The Grain for Green Program (GGP) was the most all‐embracing program of ecological reconstruction implemented in China. To estimate carbon storages and carbon sequestration potentials of the GGP forests, the study presented in the paper collected data spanning from 1999 to 2010, such as tree species, tree planting area relevant to the GGP, empirical growth curves suitable for different planted tree species in China, as well as wood density (WD), biomass expansion factor (BEF), carbon fraction (CF) of different trees species, and estimated the carbon storages of the biomasses of GGP forests from 1999 to 2050. It showed that the total carbon storage of the biomass of GGP forests was 320.29 Tg upon the GGP completion in 2010; the total carbon sequestration is higher during the early GGP‐implementation stage than at the late GGP‐implementation stage, and the annual mean carbon sequestration of GGP forests was 26.69 Tg/year. The potential of GGP forests as carbon sink presented an increasing increment. In China, the potential increments of GGP forests as carbon sinks were estimated to be 397.34, 604.00, 725.53, and 808.90 Tg in 2020, 2030, 2040, and 2050, respectively, and the carbon sequestration rates were 1.72, 0.89, 0.52, and 0.36 Mg ha^?1 year^?1, respectively, corresponding to 2010s, 2020s, 2030s, and 2040s. Therefore, the GGP forests had bigger carbon sequestration capacities and potentials in China.     

玉米对渗透胁迫的反应和生理适应

利用不同渗透势的培养液模拟土壤干旱条件,研究了玉米杂交种“中单2号”在此条件下的生长和生理的变化。实验表明,各指标对于渗透胁迫的变化敏感性顺序为叶片延伸速率、叶水势、脯氨酸含量>净光合速率>相对透性。玉米幼苗在渗透胁迫下具有一定的生理适应能力,表现在一定的渗透胁迫范围内随胁迫时间的延长,生长、生理变化有趋于缓和或恢复的趋势。     

Stoichiometric homeostasis in response to variable water and nutrient supply in a Robinia pseudoacacia plant–soil system

刺槐植物-土壤系统生态化学计量内稳性对水分和养分变异的响应特征 所有生物体都需要一定比例的元素来维持正常的生理代谢过程,它们的可塑性取决于它们利用外部资源的效率。阐明不同资源供应水平下植物、土壤和土壤微生物生物量生态化学计量特征之间的相互作用非常重要。本研究以一年生刺槐(Robinia pseudoacacia)幼苗为研究对象,测定不同水平水分、氮素和磷素处理下刺槐叶片、细根、土壤和微生物生物量C、N、P含量及其化学计量学指标。结果表明,刺槐叶片、细根、土壤和微生物生物量C、N、P含量及其化学计量特征会对其生存环境水分和养分条件的变化表现出一定程度的可塑性;方差分解分析结果表明,细根计量比解释了微生物生物量计量比方差的很大一部分;结构方程模型进一步揭示了细根计量比和叶片计量比是影响土壤微生物生物量C:N和C:P 的两个直接因素,而细根计量比具有较大的直接作用。此外,内稳性特征分析表明土壤微生物生物量C 和C:P对土壤养分变化较为敏感,其他指标均具有内稳性。这些结果明确了土壤微生物生物量化学计量的重要性,提高我们对不同生境水分和养分供应水平下植物-土壤系统养分循环机理的认识。     

Aptamer directly evolved from live cells recognizes membrane bound immunoglobin heavy mu chain in Burkitt's lymphoma cells

The identification of tumor related cell membrane protein targets is important in understanding tumor progression, the development of new diagnostic tools, and potentially for identifying new therapeutic targets. Here we present a novel strategy for identifying proteins that are altered in their expression levels in a diseased cell using cell specific aptamers. Using an intact viable B-cell Burkitt's lymphoma cell line (Ramos cells) as the target, we have selected aptamers that recognize cell membrane proteins with high affinity. Among the selected aptamers that showed different recognition patterns with different cell lines of leukemia, the aptamer TD05 showed binding with Ramos cells. By chemically modifying TD05 to covalently cross-link with its target on Ramos cells to capture and to enrich the target receptors using streptavidin coated magnetic beads followed by mass spectrometry, we were able to identify membrane bound immunoglobin heavy mu chain as the target for TD05 aptamer. Immunoglobin heavy mu chain is a major component of the B-cell antigen receptor, which is expressed in Burkitt's lymphoma cells. This study demonstrates that this two step strategy, the development of high quality aptamer probes and then the identification of their target proteins, can be used to discover new disease related potential markers and thus enhance tumor diagnosis and therapy. The aptamer based strategy will enable effective molecular elucidation of disease related biomarkers and other interesting molecules.     

Spatial patterns of photosynthetic characteristics and leaf physical traits of plants in the Loess Plateau of China

The spatial patterns of photosynthetic characteristics and leaf physical traits of 171 plants belonging to nine life-forms or functional groups (trees, shrubs, herbs, evergreen trees, deciduous trees, C₃ and C₄ herbaceous plants, leguminous and non-leguminous species) and their relationships with environmental factors in seven sites, Yangling, Yongshou, Tongchuan, Fuxian, Ansai, Mizhi and Shenmu, ranging from south to north in the Loess Plateau of China were studied. The results showed that the leaf light-saturated photosynthetic rate (P_max), photosynthetic nitrogen use efficiency (PNUE), chlorophyll content (Chl), and leaf mass per area (LMA) of all the plants in the Loess Plateau varied significantly among three life-form groups, i.e., trees, shrubs and herbs, and two groups, i.e., evergreen trees and deciduous trees, but leaf nitrogen content differed little among different life-form groups. For the 171 plants in the Loess Plateau, leaf P_max was positively correlated with PNUE. The leaf nitrogen content per unit area (N_area) was positively correlated but Chl was negatively correlated with the LMA. When controlling the LMA, the N_area was positively correlated with the Chl (partial r = 0.20, P < 0.05). With regard to relationships between photosynthetic characteristics and leaf physical traits, the P_max was positively correlated with N _area, while the PNUE was positively correlated with the Chl and negatively correlated with the N_area and LMA. For all the species in the Loess Plateau, the PNUE was negatively correlated with the latitude and annual solar radiation (ASR), but positively correlated with the mean annual rainfall (MAR) and mean annual temperature (MAT). With regard to the leaf physical traits, the leaf Chl was negatively correlated with the latitude and ASR, but positively correlated with the MAR and MAT. However, the N_area and LMA were positively correlated with the latitude and ASR, but negatively correlated with the MAR and MAT. In general, leaf N_area and LMA increased, while PNUE and Chl decreased with increases in the latitude and ASR and decreases in MAR and MAT. Electronic supplementary material The online version of this article () contains supplementary material, which is available to authorized users.     

Facile Discovery of Cell-Surface Protein Targets of Cancer Cell Aptamers

Cancer biomarker discovery constitutes a frontier in cancer research. In recent years, cell-binding aptamers have become useful molecular probes for biomarker discovery. However, there are few successful examples, and the critical barrier resides in the identification of the cell-surface protein targets for the aptamers, where only a limited number of aptamer targets have been identified so far. Herein, we developed a universal SILAC-based quantitative proteomic method for target discovery of cell-binding aptamers. The method allowed for distinguishing specific aptamer-binding proteins from nonspecific proteins based on abundance ratios of proteins bound to aptamer-carrying bait and control bait. In addition, we employed fluorescently labeled aptamers for monitoring and optimizing the binding conditions. We were able to identify and validate selectin L and integrin α4 as the protein targets for two previously reported aptamers, Sgc-3b and Sgc-4e, respectively. This strategy should be generally applicable for the discovery of protein targets for other cell-binding aptamers, which will promote the applications of these aptamers.Cancer is the leading cause of morbidity and mortality worldwide, with ∼14 million new cases and 8.2 million cancer-related deaths in 2012, and the number of new cases is expected to rise by ∼ 70% over the next two decades (1). Individual tumors may have distinct molecular profiles emanating from genetic and epigenetic alterations along with the activation of complex signaling networks (2). The use of reliable cancer biomarkers for early detection, staging, and individualized therapy may improve patient care. Along this line, Anderson et al. (3) predicted the need of biomarker panels for the detection of multiple proteins for a complex disease like cancer. Nevertheless, the elucidation of molecular alterations of cancer cells is limited by the lack of effective probes that can identify and recognize the protein biomarkers for cancer cells.Aptamers are single-stranded DNA or RNA molecules evolved from random oligonucleotide libraries by repetitive binding of the oligonucleotides to target molecules, a process known as systematic evolution of ligands by exponential enrichment (SELEX)¹ (4, 5). Similar to antibodies, aptamers can bind to their target molecules with high affinity and specificity (4, 5). Additionally, a large number of aptamers exhibiting specific binding toward a variety of cells has been identified by employing cell-based SELEX (6). These aptamers can recognize the molecular signatures of certain types of cancer cells; thus, cell-surface protein targets of aptamers may serve as candidate biomarkers for these cells.Identification of the molecular targets of the cancer-cell-specific aptamers is a crucial step toward the revelation of the molecular signatures of cancer cells and the applications of the aptamers. Although recent studies have led to the selection of more than 100 cell aptamers, protein targets for only a very limited number of these aptamers have been identified (7), which greatly hampered their applications. In this vein, aptamer-target protein binding requires a native conformation of the aptamer. On the other hand, membrane proteins are hydrophobic, poorly soluble in water, and of relatively low abundance. Thus, the identification of target protein(s) for aptamers is a challenging task. Through extraction and affinity purification of proteins of cancer cells with the use of cell-recognition aptamers, protein tyrosine kinase 7 and Siglec-5 were identified as protein targets for aptamers that can bind to T-lineage acute lymphoblastic leukemia cells (8) and acute myelogenous leukemia cells (9), respectively. In addition, an aptamer-facilitated biomarker discovery method was developed for the identification of biomarkers of immature and mature dendritic cells (10). However, it remains difficult to identify biomarkers of low abundance. By employing cross-linking with the use of an aptamer harboring a photochemically activatable nucleoside, Mallikaratchy et al. (11) identified membrane-bound immunoglobin heavy mu chain as the cell-surface protein target for aptamer TD05. However, chemical modification of an aptamer may alter its binding property, and the method is labor-intensive, rendering it impractical for large-scale discovery of aptamer targets. Recently, the same group employed a formaldehyde-induced cross-linking method and identified stress-induced phosphoprotein 1 as a potential ovarian cancer biomarker (12); many proteins were identified by mass spectrometry, rendering it very difficult to ascertain which protein is the true aptamer target.Recently, rapid advances have been made for the identification and quantifications of proteins by mass spectrometry. Among the many quantitative proteomic methods, stable-isotope labeling by amino acids in cell culture (SILAC) is simple, efficient, and accurate, and it is also suitable for the quantitative analysis of membrane proteins (13, 14). In the present study, we set out to develop a SILAC-based quantitative proteomic approach to identify cell-surface target proteins of two previously reported cell aptamers, Sgc-3b and Sgc-4e (6, 15), and we were able to identify unique cell-surface proteins that can bind to the two aptamers.