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Qiryat Shemona, Israel

Vaya J.,MIGAL Galilee Research Institute | Vaya J.,Tel-Hai Academic College
Biochemical Pharmacology | Year: 2013

Human atherosclerotic plaque is composed of a large mixture of elements, predominantly lipids and oxidized lipids, lipid-loaded macrophages and smooth muscle cells, forming foam cells. Plaque contents undergo dynamic changes during the plaque's progression, being in a constant interaction with the circulating blood. During the mutual interaction between blood and plaque and the specific biochemical processes occurring in both, specific molecules can be generated in the serum which might provide information on plaque status. This information, mostly on plaque vulnerability, is highly important for making appropriate treatment decisions before neurological symptoms appear. The present review summarizes plaque contents, mostly lipids, oxidized lipids, oxidized products of cholesterol (oxysterols), and covers the recent literature on their association with biomarkers in the blood and on the possibility of using them for providing information on plaque status. © 2013 Elsevier Inc. All rights reserved.

Zeng X.-L.,Huazhong Agricultural University | Tang K.,Huazhong Agricultural University | Zhou N.,Huazhong Agricultural University | Zhou M.,Huazhong Agricultural University | And 5 more authors.
Journal of the American Chemical Society | Year: 2013

The phycobilisomes of cyanobacteria and red-algae are highly efficient peripheral light-harvesting complexes that capture and transfer light energy in a cascade of excitation energy transfer steps through multiple phycobilin chromophores to the chlorophylls of core photosystems. In this work, we focus on the last step of this process by constructing simple functional analogs of natural phycobilisome-photosystem complexes that are based on bichromophoric protein complexes comprising a phycobilin- and a chlorophyll- or porphyrin-binding domain. The former is based on ApcE(1-240), the N-terminal chromophore-binding domain of the phycobilisome's LCM core-membrane linker, and the latter on HP7, a de novo designed four-helix bundle protein that was originally planned as a high-affinity heme-binding protein, analogous to b-type cytochromes. We fused a modified HP7 protein sequence to ApcEΔ, a water-soluble fragment of ApcE(1-240) obtained by excising a putative hydrophobic loop sequence of residues 77-153. HP7 was fused either to the N- or the C-terminus of ApcEΔ or inserted between residues 76 and 78, thereby replacing the native hydrophobic loop domain. We describe the assembly, spectral characteristics, and intramolecular excitation energy transfer of two unique systems: in the first, the short-wavelength absorbing zinc-mesoporphyrin is bound to the HP7 domain and serves as an excitation-energy donor to the long-wavelength absorbing phycocyanobilin bound to the ApcE domain; in the second, the short-wavelength absorbing phycoerythrobilin is bound to the ApcE domain and serves as an excitation energy donor to the long-wavelength absorbing zinc-bacteriochlorophyllide bound to the HP7 domain. All the systems that were constructed and tested exhibited significant intramolecular fluorescence resonance energy transfer with yields ranging from 21% to 50%. This confirms that our modular, covalent approach for studying EET between the cyclic and open chain tetrapyrroles is reasonable, and may be extended to larger structures mimicking light-harvesting in cyanobacteria. The design, construction, and characterization process demonstrated many of the advances in constructing such model systems, particularly in our ability to control the fold and aggregation state of protein-based systems. At the same time, it underlines the potential of exploiting the versatility and flexibility of protein-based systems in assembling multiple pigments into effective light-harvesting arrays and tuning the spectral properties of multichromophore systems. © 2013 American Chemical Society.

Galili G.,Weizmann Institute of Science | Amir R.,MIGAL Galilee Research Institute | Fernie A.R.,Max Planck Institute of Molecular Plant Physiology
Annual Review of Plant Biology | Year: 2016

Although amino acids are critical for all forms of life, only proteogenic amino acids that humans and animals cannot synthesize de novo and therefore must acquire in their diets are classified as essential. Nine amino acids-lysine, methionine, threonine, phenylalanine, tryptophan, valine, isoleucine, leucine, and histidine-fit this definition. Despite their nutritional importance, several of these amino acids are present in limiting quantities in many of the world's major crops. In recent years, a combination of reverse genetic and biochemical approaches has been used to define the genes encoding the enzymes responsible for synthesizing, degrading, and regulating these amino acids. In this review, we describe recent advances in our understanding of the metabolism of the essential amino acids, discuss approaches for enhancing their levels in plants, and appraise efforts toward their biofortification in crop plants. Copyright © 2016 by Annual Reviews. All rights reserved.

Bednarczyk D.,Weizmann Institute of Science | Noy D.,MIGAL Galilee Research Institute
Journal of Visualized Experiments | Year: 2016

Chlorophylls (Chls) and bacteriochlorophylls (BChls) are the primary cofactors that carry out photosynthetic light harvesting and electron transport. Their functionality critically depends on their specific organization within large and elaborate multisubunit transmembrane protein complexes. In order to understand at the molecular level how these complexes facilitate solar energy conversion, it is essential to understand protein-pigment, and pigment-pigment interactions, and their effect on excited dynamics. One way of gaining such understanding is by constructing and studying complexes of Chls with simple water-soluble recombinant proteins. However, incorporating the lipophilic Chls and BChls into water-soluble proteins is difficult. Moreover, there is no general method, which could be used for assembly of water-soluble proteins with hydrophobic pigments. Here, we demonstrate a simple and high throughput system based on water-in-oil emulsions, which enables assembly of water-soluble proteins with hydrophobic Chls. The new method was validated by assembling recombinant versions of the watersoluble chlorophyll binding protein of Brassicaceae plants (WSCP) with Chl a. We demonstrate the successful assembly of Chl a using crude lysates of WSCP expressing E. coli cell, which may be used for developing a genetic screen system for novel water-soluble Chl-binding proteins, and for studies of Chl-protein interactions and assembly processes. © 2016 Journal of Visualized Experiments.

Small fruit size is a limiting factor in marketing apples (Malus × domestica). Several techniques have been used to improve this trait, among them blossom and fruit thinning with plant growth regulators such as auxins and cytokinins to reduce crop load. In the present study, carried out in 3 consecutive years (2011-2013), we evaluated the photosynthesis inhibitor metamitron (MM) as a thinner for 'Gala' apples. MM was applied twice at 150 g ha-1 (in the form of 0.085% Brevis®) at the 6- and 10-mm diameter stages, or once at 180 g ha-1 (0.1% Brevis® at 1,200 L ha-1) at the 6-mm stage, resulted in significant thinning. Consequently, the average time spent on hand thinning was reduced from 40-80 day ha-1 to 10-20 day ha-1. However, crop load was only slightly affected, depending on the year. In "ON" years, there was a considerable and significant shift to larger fruit size. The relatively low effective doses of MM, compared to those used in Europe and the USA, were likely to be due to the higher night temperatures for 3 weeks post application, which increased respiration and caused assimilation deficiencies during that critical period of fruit development. No negative effects were observed on the return bloom in the following year.

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