Proteome and Lipidome of Plant Cell Membranes during Development

Intensive development of systemic biology involves intensification of such branches as proteomics and lipidomics, which are valid for systemic biology of plants. This trend is obvious due to the rapidly growing number of publications on proteomes and lipidomes of plant cells, tissues, and whole organs. Particulars of the plant nuclei, mitochondria, and chloroplasts have been rather well detailed in this regard. However, these data are scarce concerning the tonoplast, Golgi apparatus, endoplasmic reticulum, and other single-membrane organelles of the plant cell. This review surveys the current concepts related to specificity of protein and lipid spectra in the membrane structures of plant cells. The little data describing changes in these parameters in the course of development and under stress pressure are also analyzed.

Potential Antibacterial Activity of Bioactive β-sitosterol from Root Bark of Rhizophora apiculata from Lampung Coastal

β-sitosterol is an essential bioactive phytosterol naturally present in plant cell membranes. It has a coincident structure with animal cholesterol. This investigation reported isolation, structure analysis, and an antimicrobial assay of β-sitosterol from the root bark of Bakau Minyak (Rhizophora apiculata) from Lampung coastal. The isolation of β-sitosterol was carried out through maceration using methanol, separation by vacuum liquid chromatography (VLC), and purification by column chromatography (CC) using ethyl acetate/n-hexane (2:8) as eluent. The structure of β-sitosterol was determined using spectroscopic analysis (UV-Vis, FT-IR, 13C-NMR, 1H-NMR, DEPT, and GC-MS). The pure β-sitosterol has 107.4 mg of white needle crystalline compound, the compound melting point about 140.7-141.2oC, the molecular mass confirmed by m/z 414, and UV absorption detected at λ 203.9 nm. The β-sitosterol antimicrobial bioactivity assay has shown potential activity to be developed as a lead compound against E. coli.

The adaptive capabilities of Elodea canadensis under the influence of anthropogenic factors

Studies on the potential adaptation of one of the common aquatic macrophytes Elodea canadensis when immersed in a medium containing anthropogenic pollutants of various origins – metals (inorganic salts); organic salts, mineral acids; oil and its derivatives - water-soluble petrochemicals. It was found that almost all the studied pollutants do not show a clear external effect on the solid fragments of the plant (cell membranes). Thus, it was shown that Elodea canadensis is tolerant of anthropogenic pollutants that differ in nature, hazard class, physico-chemical properties, etc.

The role of sterols in plant response to abiotic stress

Sterols are integral components of the membrane lipid bilayer and they are involved in many processes occurring in plants, ranging from regulation of growth and development to stress resistance. Maintenance of membrane homeostasis represents one of the principal functions of sterols in plant cells. Plant cell membranes are important sites of perception of environmental abiotic factors, therefore, it can be surmised that sterols may play an important role in the plant stress response. The aim of this review was to discuss the most representative trends in recent studies regarding the role of sterols in plant defense reactions to environmental factors, such as UV radiation, cold and drought stress. Some correlations were observed between changes in the sterol profile, referring to the ratios of individual compounds (including 24-methyl/ethyl sterols and sitosterol/stigmasterol) as well as the relative proportions of conjugated sterols (ASGs, SGs and SEs) and the nature of the stress response. Diversity of sterols and their conjugated forms may allow sessile plants to adapt to environmental stress conditions.

Detection of Lupeol in Calendula Officinalis Grown in Iraq by GC-MS Analysis

Triterpenes are abundant group of natural compounds with important structural components of plant’s cell membranes. Free triterpenes stabilize phospholipid bilayers in plant cell membranes just as cholesterol does in animal cell membranes. Lupeol is a pentacyclic trite- rpene reported to have important physiological and therapeutic effects in human health issues, therefore its extraction from Calendula officinalis flowers and detection by GC-MS is of significant importance.

Causal Enzymology and Physiological Aspects May Be Accountable to Membrane Integrity in Response to Salt Stress in Arabidopsis thaliana Lines

Apart from their significance in the protection against stress conditions, the plant cell membranes are essential for proper development of the diverse surface structures formed on aerial plant organs. In addition, we signal that membrane remodeling and integrity are function of some of causal physiological and enzymological aspects such as the MDA, the ion leakage and also the monitoring of some phytozymes involved in lipid and cellulose metabolisms. Those last ones are related to the membrane structure (lipases and cellulases), that were assessed in durum wheat dehydrin transgenic context (YS, K1-K2, DH2, and DH4), proline metabolic mutant (P5CS1-4) per comparison with the wild-type plant (Wt). We report also the docking data reinforcing the fact that the membrane integrity seems to be function of causal enzymological behaviors, through the molecular dynamic investigation resulting from the dehydrin-phytozyme interactions and also from the inhibition effect of the durum wheat LTP4 on the lipase activity.

Phosphatidic acids mediate transport of Ca2+ and H+ through plant cell membranes

Phosphatidic acids (PAs) are a key intermediate in phospholipid biosynthesis, and a central element in numerous signalling pathways. Functions of PAs are related to their fundamental role in molecular interactions within cell membranes modifying membrane bending, budding, fission and fusion. Here we tested the hypothesis that PAs are capable of direct transport of ions across bio-membranes. We have demonstrated that PAs added to the maize plasma membrane vesicles induced ionophore-like transmembrane transport of Ca2+, H+ and Mg2+. PA-induced Ca2+ fluxes increased with an increasing PAs acyl chain unsaturation. For all the PAs analysed, the effect on Ca2+ permeability increased with increasing pH (pH 8.0>pH 7.2>pH 6.0). The PA-induced Ca2+, Mg2+ and H+ permeability was also more pronounced in the endomembrane vesicles as compared with the plasma membrane vesicles. Addition of PA to protoplasts from Arabidopsis thaliana (L.) Heynh. roots constitutively expressing aequorin triggered elevation of the cytosolic Ca2+ activity, indicating that the observed PA-dependent Ca2+ transport occurs in intact plants.

Advances in Understanding the Mechanism of Action of the Auxin Permease AUX1

In over 40 years of research on the cellular uptake of auxin it is somewhat chastening that we have elaborated so little on the original kinetic descriptions of auxin uptake by plant cells made by Rubery and Sheldrake in 1974. Every aspect of that seminal work has been investigated in detail, and the uptake activity they measured is now known to be attributed to the AUX1/LAX family of permeases. Recent pharmacological studies have defined the substrate specificity of AUX1, biochemical studies have evaluated its permeability to auxin in plant cell membranes, and rigourous kinetic studies have confirmed the affinity of AUX1 for IAA and synthetic auxins. Advances in genome sequencing have provided a rich resource for informatic analysis of the ancestry of AUX1 and the LAX proteins and, along with models of topology, suggest mechanistic links to families of eukaryotic proton co-transporters for which crystal structures have been presented. The insights gained from all the accumulated research reflect the brilliance of Rubery and Sheldrake’s early work, but recent biochemical analyses are starting to advance further our understanding of this vitally important family of auxin transport proteins.