Global spectroscopic analysis to study the regulation of the photosynthetic proton motive force: A critical reappraisal.

In natural variable environments, plants rapidly adjust photosynthesis for optimum balance between photochemistry and photoprotection. These adjustments mainly occur via changes in their proton motive force (pmf). Recent studies based on time resolved analysis of the Electro Chromic Signal (ECS) bandshift of photosynthetic pigments in the model plant Arabidopsis thaliana have suggested an active role of ion fluxes across the thylakoid membranes in the regulation of the pmf.

The crystal structure of a new ferrocenyl P,N ligand: 1-[(2,2-di-methyl-hydrazin-1-yl-idene)meth-yl]-1'-(di-phenyl-phospho-rothio-yl)ferrocene.

The asymmetric unit of the title compound, [Fe(CHN)(CHPS)], contains two independent mol-ecules ( and ) with very similar conformations. Each mol-ecule is built up from a ferrocene unit substituted in the 1 and 1' positions by a protected sulfur di-phenyl-phosphine and by a di-methyl-hydrazine, -C(H)=N-N(CH), fragment. The two independent mol-ecules are linked by a C-H⋯N hydrogen bond.

Genomics analysis of Aphanomyces spp. identifies a new class of oomycete effector associated with host adaptation.

Background: Oomycetes are a group of filamentous eukaryotic microorganisms that have colonized all terrestrial and oceanic ecosystems, and they include prominent plant pathogens. The Aphanomyces genus is unique in its ability to infect both plant and animal species, and as such exemplifies oomycete versatility in adapting to different hosts and environments. Dissecting the underpinnings of oomycete diversity provides insights into their specificity and pathogenic mechanisms.

Optimization of lipids' ultrasonic extraction and production from Chlorella sp. using response-surface methodology.

Background: Three steps are very important in order to produce microalgal lipids: (1) controlling microalgae cultivation via experimental and modeling investigations, (2) optimizing culture conditions to maximize lipids production and to determine the fatty acid profile the most appropriate for biodiesel synthesis, and (3) optimizing the extraction of the lipids accumulated in the microalgal cells.

Methods: Firstly, three kinetics models, namely logistic, logistic-with-lag and modified Gompertz, were tested to fit the experimental kinetics of the Chlorella sp. microalga culture established on standard conditions.

A combined pathway of organogenesis and somatic embryogenesis for an efficient large-scale propagation in date palm ( L.) cv. Mejhoul.

An efficient regeneration system via a combined pathway of organogenesis and somatic embryogenesis was developed for date palm ( L.) cv. Mejhoul.

Effects of low temperature plasmas and plasma activated waters on Arabidopsis thaliana germination and growth.

Two plasma devices at atmospheric pressure (air dielectric barrier discharge and helium plasma jet) have been used to study the early germination of Arabidopsis thaliana seeds during the first days. Then, plasma activated waters are used during the later stage of plant development and growth until 42 days. The effects on both testa and endospserm ruptures during the germination stage are significant in the case of air plasma due to its higher energy and efficiency of producing reactive oxygen species than the case of helium plasma.

The plastoquinone pool outside the thylakoid membrane serves in plant photoprotection as a reservoir of singlet oxygen scavengers.

The Arabidopsis vte1 mutant is devoid of tocopherol and plastochromanol (PC-8). When exposed to excess light energy, vte1 produced more singlet oxygen ( O ) and suffered from extensive oxidative damage compared with the wild type. Here, we show that overexpressing the solanesyl diphosphate synthase 1 (SPS1) gene in vte1 induced a marked accumulation of total plastoquinone (PQ-9) and rendered the vte1 SPS1oex plants tolerant to photooxidative stress, indicating that PQ-9 can replace tocopherol and PC-8 in photoprotection.

Auxin Response Factors (ARFs) are potential mediators of auxin action in tomato response to biotic and abiotic stress (Solanum lycopersicum).

Survival biomass production and crop yield are heavily constrained by a wide range of environmental stresses. Several phytohormones among which abscisic acid (ABA), ethylene and salicylic acid (SA) are known to mediate plant responses to these stresses. By contrast, the role of the plant hormone auxin in stress responses remains so far poorly studied.

Modelling Tetraselmis sp. growth-kinetics and optimizing bioactive-compound production through environmental conditions.

The aim of this study is to predict Tetraselmis cells growth-kinetic and to induce the synthesis of bioactive compounds (chlorophylls, carotenoids and starch) with high potential for biotechnological applications. Using the statistical criteria, the Baranyi-Roberts model has been selected to estimate the microalgae growth-kinetic values. The simultaneous effects of salinity, light intensity and pH of culture medium were investigated to maximize the production of total chlorophylls, carotenoids and starch.

Proteomic Analysis of the Chlorophyta Dunaliella New Strain AL-1 Revealed Global Changes of Metabolism during High Carotenoid Production.

The green microalgae genus is known for the production of high added value molecules. In this study, strain AL-1 was isolated from the Sebkha of Sidi El Hani (Sousse, Tunisia). This isolate was identified both morphologically and genetically via 18S rRNA gene sequence as a member of the genus .

A systems-wide understanding of photosynthetic acclimation in algae and higher plants.

The ability of phototrophs to colonise different environments relies on robust protection against oxidative stress, a critical requirement for the successful evolutionary transition from water to land. Photosynthetic organisms have developed numerous strategies to adapt their photosynthetic apparatus to changing light conditions in order to optimise their photosynthetic yield, which is crucial for life on Earth to exist. Photosynthetic acclimation is an excellent example of the complexity of biological systems, where highly diverse processes, ranging from electron excitation over protein protonation to enzymatic processes coupling ion gradients with biosynthetic activity, interact on drastically different timescales from picoseconds to hours.

Cyanobacteria as source of marine bioactive compounds: Molecular specific detection based on Δ9 desaturase gene.

The blue-green microalga, Arthrospira sp., isolated from the sea of Kssour Essef in Mahdia (Tunisia), was purified and then identified both morphologically and genetically based on 16S rRNA gene sequence. Following physicochemical analysis, the prokaryotic microalga tested represented a competitive source of pigments and showed a considerable rate in protein (64%) which was confirmed by FTIR measurement.

The plasma membrane proteome of Medicago truncatula roots as modified by arbuscular mycorrhizal symbiosis.

In arbuscular mycorrhizal (AM) roots, the plasma membrane (PM) of the host plant is involved in all developmental stages of the symbiotic interaction, from initial recognition to intracellular accommodation of intra-radical hyphae and arbuscules. Although the role of the PM as the agent for cellular morphogenesis and nutrient exchange is especially accentuated in endosymbiosis, very little is known regarding the PM protein composition of mycorrhizal roots. To obtain a global overview at the proteome level of the host PM proteins as modified by symbiosis, we performed a comparative protein profiling of PM fractions from Medicago truncatula roots either inoculated or not with the AM fungus Rhizophagus irregularis.

Plastid thylakoid architecture optimizes photosynthesis in diatoms.

Photosynthesis is a unique process that allows independent colonization of the land by plants and of the oceans by phytoplankton. Although the photosynthesis process is well understood in plants, we are still unlocking the mechanisms evolved by phytoplankton to achieve extremely efficient photosynthesis. Here, we combine biochemical, structural and in vivo physiological studies to unravel the structure of the plastid in diatoms, prominent marine eukaryotes.

The Arabidopsis guard cell outward potassium channel GORK is regulated by CPK33.

A complex signaling network involving voltage-gated potassium channels from the Shaker family contributes to the regulation of stomatal aperture. Several kinases and phosphatases have been shown to be crucial for ABA-dependent regulation of the ion transporters. To date, the Ca -dependent regulation of Shaker channels by Ca -dependent protein kinases (CPKs) is still elusive.

Somatic embryogenesis from bud and leaf explants of date palm (Phoenix dactylifera L.) cv. Najda.

An efficient regeneration system through somatic embryogenesis was developed for date palm cv. Najda. Adventitious bud and proximal leaf segments cultured on Murashige and Skoog (MS) medium supplemented with various combinations of auxins and cytokinins induced embryogenesis after at least 6 months of culture.

An update on the regulation of photosynthesis by thylakoid ion channels and transporters in Arabidopsis.

In natural, variable environments, plants rapidly adjust photosynthesis for optimal balance between light absorption and utilization. There is increasing evidence suggesting that ion fluxes across the chloroplast thylakoid membrane play an important role in this regulation by affecting the proton motive force and consequently photosynthesis and thylakoid membrane ultrastructure. This article presents an update on the thylakoid ion channels and transporters characterized in Arabidopsis thaliana as being involved in these processes, as well as an outlook at the evolutionary conservation of their functions in other photosynthetic organisms.

Immunity at Cauliflower Hydathodes Controls Systemic Infection by pv .

Hydathodes are water pores found on leaves of a wide range of vascular plants and are the sites of guttation. We report here on the detailed anatomy of cauliflower () and Arabidopsis () hydathodes. Hydathode surface presents pores resembling stomata giving access to large cavities.

Phytochemical composition and antioxidant activity of medicinal plants collected from the Tunisian flora.

Polyphenols, flavonoids and condensed tannins contents, as well as the antioxidant activity of the ethanolic and aqueous extracts obtained from aerial parts of 10 wild Tunisian plants, have been determined. Extracts showed appreciable levels of polyphenols and flavonoids, which reached 215.16 mg GAE g DW in Lavandula stoechas ethanolic extract, and 49.

Asteraceae and Essential Oils Trigger Apoptosis and Cell Cycle Arrest in Promastigotes.

We report the chemical composition and anti- and antioxidant activity of L. and - Asso. essential oils (EOs).

Isolation of Chromoplasts and Suborganellar Compartments from Tomato and Bell Pepper Fruit.

Tomato is a model for fruit development and ripening. The isolation of intact plastids from this organism is therefore important for metabolic and proteomic analyses. Pepper, a species from the same family, is also of interest since it allows isolation of intact chromoplasts in large amounts.

Cyclic electron flow: facts and hypotheses.

Over the last 15 years, research into the process of cyclic electron flow in photosynthesis has seen a huge resurgence. Having been considered by some in the early 1990s as a physiologically unimportant artefact, it is now recognised as essential to normal plant growth. Here, we provide an overview of the major developments covered in this special issue of photosynthesis research.

Calcium- and Nitric Oxide-Dependent Nuclear Accumulation of Cytosolic Glyceraldehyde-3-Phosphate Dehydrogenase in Response to Long Chain Bases in Tobacco BY-2 Cells.

Sphinganine or dihydrosphingosine (d18:0, DHS), one of the most abundant free sphingoid long chain bases (LCBs) in plants, is known to induce a calcium-dependent programmed cell death (PCD) in plants. In addition, in tobacco BY-2 cells, it has been shown that DHS triggers a rapid production of HO and nitric oxide (NO). Recently, in analogy to what is known in the animal field, plant cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC), a ubiquitous enzyme involved in glycolysis, has been suggested to fulfill other functions associated with its oxidative post-translational modifications such as S-nitrosylation on cysteine residues.

Evaluation of antidiabetic effect of total calystegines extracted from Hyoscyamus albus.

Background: Hyoscyamus albus L. (Solanaceae) an old medicinal plant is a rich source of tropane and nortropane alkaloids which confers to this plant a number of very interesting and beneficial therapeutic effects.

Purpose: Calystegines that are polyhydroxylated alkaloids and imino-sugars poccess significant glycosidases inhibitory activities and are therefore good candidats for the treatment of diabetes mellitus.

Quorum-Sensing Mechanisms and Bacterial Response to Antibiotics in P. aeruginosa.

Emergence and worldwide spreading of resistant bacteria to antibiotic have raised the importance for finding therapeutic alternative to compensate antibiotic drawbacks. Quorum sensing (QS) is a cell-to-cell communication involved in the development of various common bacterial behaviors including virulence factors expression, and targeting QS seems to be relevant to the struggle against bacterial infection. In this report, relevant literature on intrication of QS system and antimicrobial sensitivity mechanisms in P.