Comparative Proteomic Analysis Reveals Nitrogen Fertilizer Increases Spikelet Number per Panicle in Rice by Repressing Protein Degradation and 14-3-3 Proteins

The spikelet number per panicle is established in the early stages of panicle development. Nitrogen fertilizer application before panicle initiation is known to increase spikelet number, which is one of the most important traits in rice productivity determination. However, the basic proteomic mechanism remains poorly understood. The present study shows that nitrogen fertilizer significantly increased spikelet number and grain yield in rice. Proteomic variations were further analyzed in young panicles at the secondary panicle branch initiation and spikelet meristem initiation under nitrogen fertilizer treatment. Proteomic analysis identified 63 proteins with significant differential accumulation in young panicles under nitrogen fertilizer treatment. Proteolysis represents the largest functional category, which suggests that protein degradation is an important pathway in the response to nitrogen fertilizer. Importantly, nitrogen fertilizer significantly reduced 14-3-3 proteins, which interact with key enzymes associated with carbon and nitrogen metabolism, and the rice FT homologue Hd3a. Real-time PCR revealed that Hd3a signaling is also repressed by nitrogen fertilizer in leaves. This study contributes to a better understanding of the regulation of nitrogen fertilizers in the flowering pathway leading to panicle development. The identification of novel genes provides new insight into the profound impacts of nitrogen fertilizer on panicle development in rice.     

太湖流域丘陵区两种土地利用类型土壤水分分布控制因素

为探究太湖流域丘陵区典型土地利用类型(如竹林地和茶园)土壤水分的控制因素,在不同深度土壤水分定期观测的基础上,根据前7d降雨量将研究时段划分为干旱状态和湿润状态,利用分类与回归树(CART)方法得出不同干湿状态下土壤水分分布的主控因子,并借助典范对应分析(CCA)定量分析不同土地利用类型、不同土壤深度土壤水分格局与环境因子关系。结果表明:(1)高程、土地利用类型和土层厚度对土壤水分分布的相对贡献率最大,但在不同干湿状态下其影响程度存在差异;(2)干旱状态时土壤水分主要受高程、坡度、地形湿度指数(TWI)和剖面曲率等地形因素的作用,而土层厚度和粘粒也分别为0—20 cm和20—40 cm深度土壤水分的主控因子;(3)在湿润状态下,茶园0—20 cm土壤水分的主控因素为地形因子,在20—40 cm则以土壤性质为主,竹林地两个深度的土壤水分受地形和土壤性质的作用都很强,其中20—40 cm深度土壤水分与环境因子的关系较0—20 cm深度更为复杂。     

Silicon Alleviates Cadmium Toxicity in Two Cypress Varieties by Strengthening the Exodermis Tissues and Stimulating Phenolic Exudation of Roots

The aim of this work was to investigate the effect of silicon (Si) on phenolic exudation of plant roots and cadmium (Cd) bioavailability in rhizospheres. For this purpose, pot experiments with two cypress varieties, Juniperus chinensis and Platycladus orientalis, each subjected to 100 mg kg^?1 Cd and/or 400 mg kg^?1 Si for 220 days, were conducted using a rhizobag technique. The results showed that P. orientalis accumulated a higher amount of Cd, hence caused higher growth inhibition on the leaves compared with J. chinensis. Si alleviated the growth inhibition induced by Cd toxicity on both varieties, but the mechanisms involved were species specific. For J. chinensis, Si did not affect the root exudation but enhanced the Cd retention of the roots by strengthening the exodermis tissues, restraining Cd translocation from the roots to the shoots. For P. orientalis, Si exposure significantly elevated the phenolic exudation (for example, ferulic acid, catechin, and gallic acid) of the roots, which caused greater Cd mobility in the rhizosphere and enhancement of Cd accumulation in the shoots compared with Cd treatment alone. These results suggest that Cd-chelating with the Si-induced phenolics in the rhizosphere is involved in the Cd detoxification in P. orientalis.     

A hidden aggregation‐prone structure in the heart of hypoxia inducible factor prolyl hydroxylase

Prolyl hydroxylase domain‐containing protein 2 (PHD2), as one of the most important regulators of angiogenesis and metastasis of cancer cells, is a promising target for cancer therapy drug design. Progressive studies imply that abnormality in PHD2 function may be due to misfolding. Therefore, study of the PHD2 unfolding pathway paves the way for a better understanding of the influence of PHD2 mutations and cancer cell metabolites on the protein folding pathway. We study the unfolding of the PHD2 catalytic domain using differential scanning calorimetry (DSC), fluorescence spectroscopy, and discrete molecular dynamics simulations (DMD). Using computational and experimental techniques, we find that PHD2 undergoes four transitions along the thermal unfolding pathway. To illustrate PHD2 unfolding events in atomic detail, we utilize DMD simulations. Analysis of computational results indicates an intermediate species in the PHD2 unfolding pathway that may enhance aggregation propensity, explaining mutation‐independent PHD2 malfunction. Proteins 2016; 84:611–623. © 2016 Wiley Periodicals, Inc.     

乙醇胁迫抑制毕赤酵母表达外源蛋白的转录组学分析

在5 L发酵罐中进行毕赤酵母发酵表达猪?干扰素的实验,发现甘油培养末期乙醇的积累会抑制外源蛋白的表达。从转录组学角度系统分析不同浓度乙醇胁迫条件下,毕赤酵母甘油培养期和甲醇诱导期细胞的生理状态变化。研究结果表明,在甘油培养期,乙醇胁迫使得毕赤酵母细胞中的545个基因发生了显著差异表达(265个基因表达上调,280个基因表达下调),这些差异表达基因的功能主要涉及蛋白质合成、能量代谢、细胞周期和过氧化物酶代谢。乙醇胁迫增加了蛋白质错误折叠的情况,降低了核糖体和线粒体的结构完整性,使得甘油培养末期无法得到大量具有健全功能的酵母细胞。在甲醇诱导期,与甲醇代谢、蛋白质加工合成、氨基酸代谢等途径相关的294个基因发生了显著差异表达(171个基因表达上调,123个基因表达下调),导致内质网胁迫不能被及时解除,破坏了细胞内的氨基酸正常代谢。