Plant VDAC: Facts and speculations

The voltage-dependent anion-selective channel (VDAC) is the most abundant protein in the mitochondrial outer membrane and the major transport pathway for a large variety of compounds ranging from ions to large polymeric molecules such as DNA and tRNA. Plant VDACs feature a secondary structure content and electrophysiological properties akin to those of VDACs from other organisms. They however undergo a specific regulation. The general importance of VDAC in plant physiology has only recently emerged. Besides their role in metabolite transport, plant VDACs are also involved in the programmed cell death triggered in response to biotic and abiotic stresses. Moreover, their colocalization in non-mitochondrial membranes suggests a diversity of function. This review summarizes our current understanding of the structure and function of plant VDACs. This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism.     

植物激素与谷类作物籽粒发育

介绍了细胞分裂素、赤霉素、生长素和脱落酸与谷类作物籽粒发育之间的关系。     

Metabolism and Plant Hormone Action During Clubroot Disease

Infection of Brassicaceae with the obligate biotrophic pathogen Plasmodiophora brassicae results in the development of root galls (clubroots). During the transformation of a healthy root to a root gall a plethora of changes in primary and secondary metabolism occur. The upper part of an infected plant is retarded in growth due to redirection of assimilates from the shoot to the root. In addition, changes in the levels of plant growth regulators, especially auxins and cytokinins, contribute to the hypertrophy of infected roots. Also, defense reactions are manipulated after inoculation of suitable host plants with P. brassicae. This review summarizes our current knowledge on the changes in these parameters. A model is presented for how primary metabolism and secondary metabolism, including plant hormones, interact to induce clubroot formation.     

基于植物功能性状的生态学研究进展:从个体水平到全球尺度

植物功能性状是指能够反映植物碳获取、水分传递、养分循环等的重要生命活动的属性,包括植物生理、形态和物候等方面的特征。通过植物功能性状探讨物种分布格局、生长策略和存活机制及其对全球变化的响应与适应,是近年来生态学研究的热点之一。然而,不同尺度下植物功能性状与环境因子的关系存在差异,并且性状之间的关系也不尽相同。从物种、种群、群落、植被区系到全球尺度,围绕植物功能性状之间的相互关系及其对气候环境变化响应的热点问题进行了综述,梳理了近年来植物功能性状研究领域的进展,并讨论了目前植物功能性状研究的局限性和该领域未来的发展趋势。     

Trends In Growth Hormone Stimulation Testing And Growth Hormone Dosing In Adult Growth Hormone Deficiency Patients: Results From The Answer Program

Objective: Adult growth hormone deficiency (AGHD) results in physiologic impairments that may reduce quality of life and negatively impact body composition. AGHD can be treated with recombinant human growth hormone (GH). This study analyzes AGHD patients enrolled in the American Norditropin® Studies: Web-Enabled-Research (ANSWER) Program/NovoNet, a U.S. observational noninterventional study of patients treated with Norditropin® (somatropin [recombinant DNA origin] injection) at the discretion of their physicians.Methods: Data were evaluated for GH stimulation test (GHST) usage and Norditropin® doses over 4 years.Results: Adults (N = 468) with isolated GHD (IGHD) or multiple pituitary hormone deficiency (MPHD) were evaluated. The most commonly used GHSTs were arginine + L-dopa (27%; mostly a single center) and glucagon (25%; most frequent test after 2009). The percent of patients meeting recommended test-specific cut points varied from 32 to 100%, depending on the GHST used. Mean baseline GH doses were higher for MPHD patients and for younger patients in both IGHD and MPHD groups.Conclusion: MPHD was more common than IGHD. Mean GH doses were higher in younger patients, consistent with a transition from higher pediatric to lower adult dosing. Over time, glucagon became the most popular GHST. The use, in some patients, of other GHSTs with cut points, as well as starting doses not consistent with current recommendations, highlights the need for continued education regarding treatment guidelines for AGHD.Abbreviations:AACE = American Association of Clinical EndocrinologistsAGHD = adult growth hormone deficiencyANSWER = American Norditropin® Studies: Web-Enabled-ResearchBMI = body mass indexGH = growth hormoneGHD = growth hormone deficiencyGHRH = growth hormone-releasing hormoneGHST = growth hormone stimulation testIGF-1 = insulin-like growth factor-1IGHD = isolated growth hormone deficiencyITT = insulin tolerance testKIMS = Pfizer International Metabolic DatabaseMPHD = multiple pituitary hormone deficiencyTES = The Endocrine Society     

植物愈伤组织培养中内外源激素效应的研究现状与展望

综述了外源激素对愈伤组织诱导、分化的影响,以及内源激素在愈伤组织培养过程中的变化规律。有关愈伤组织培养中外源激素作用的研究日趋细化,而激素变化与适宜继代周期的关系已成为研究热点。随着分子生物学与同位素标记等技术的引入,必将促进愈伤组织培养中激素相关基因调控机理的揭示,以及激素作用位点的精确定位,从而推动植物愈伤组织培养的迅猛发展。     

7-Rhamnosylated Flavonols Modulate Homeostasis of the Plant Hormone Auxin and Affect Plant Development

Flavonols are a group of secondary metabolites that affect diverse cellular processes. They are considered putative negative regulators of the transport of the phytohormone auxin, by which they influence auxin distribution and concomitantly take part in the control of plant organ development. Flavonols are accumulating in a large number of glycosidic forms. Whether these have distinct functions and diverse cellular targets is not well understood. The rol1-2 mutant of Arabidopsis thaliana is characterized by a modified flavonol glycosylation profile that is inducing changes in auxin transport and growth defects in shoot tissues. To determine whether specific flavonol glycosides are responsible for these phenotypes, a suppressor screen was performed on the rol1-2 mutant, resulting in the identification of an allelic series of UGT89C1, a gene encoding a flavonol 7-O-rhamnosyltransferase. A detailed analysis revealed that interfering with flavonol rhamnosylation increases the concentration of auxin precursors and auxin metabolites, whereas auxin transport is not affected. This finding provides an additional level of complexity to the possible ways by which flavonols influence auxin distribution and suggests that flavonol glycosides play an important role in regulating plant development.     

Production of Plant Made Pharmaceuticals: From Plant Host to Functional Protein

In the last two decades plants have emerged as valuable alternatives to mammalian cells for the production of pharmaceuticals and their potential as expression systems was shown by the commercial availability and acceptance of several plant made therapeuticals in clinical trials. Plants have many advantages over yeast, insect and bacterial expression systems such as the potential to properly fold the expressed proteins and the synthesis of more human-like N-glycans on the proteins. However, several constraints, such as expression yields, downstream processing and structural authenticity, currently limit the widespread use of plant expression systems. In this review, the focus is on the current limitations of plant systems for the production of pharmaceuticals and the possibilities to overcome these obstacles. A comparison is made with insect cell and yeast expression systems. Furthermore, the importance of glycosylation, in particular N-glycosylation for the biological function(s) of therapeutics in the human body will be discussed in detail and an overview of the state of art in the humanization of the N-glycosylation pathway in plants is provided.