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Bettini S.,University of Salento | Santino A.,Institute Of Science Of Food Production Cnr Unit Of Lecce | Giancane G.,University of Salento | Valli L.,University of Salento
Colloids and Surfaces B: Biointerfaces | Year: 2014

Oil bodies (OBs) are micelle-like structures with an outer phospholipid monolayer embedding some specific proteins (oleosins) and surrounding a hydrophobic core of triacylglycerols (TAGs). Oleosins are alkaline hairpin-like proteins that are anchored into the OBs structure with their hydrophilic domains covering the surface. We performed surface pressure (Π) and Brewster Angle Microscopy investigations of reconstituted OBs (ROBs) and of trypsin digested ROBs. The obtained Π vs time isotherms clearly show the formation of a surface layer. Upon ROBs suspension injection into the subphase, a clear-cut Π enhancement is recorded, followed by a long plateau region for ROBs suspensions more concentrated than 12.5. μg/ml. The BAM analysis highlighted the presence of a dark background, ascribable to a 2D layer due to free components rearrangement and brilliant circular 3D domains, due to unaltered ROBs or small aggregates of ROBs. Increasing ROBs concentration, large domains appeared. We hypothesize that the presence of an excess of free TAGs in the 2D layer is crucial for the generation of such domains. We verified the generation of such typical structures, studying the behavior of a ROBs suspension (concentration of 12.5. μg/ml) with two different approaches: after injection under a concentrated TAGs floating layers and after digestion with trypsin. These two procedures resulted in similar effects since proteinase digestion is like to induce the same morphology of a TAGs excess. © 2014 Elsevier B.V.

de Domenico S.,Institute Of Science Of Food Production Cnr Unit Of Lecce | Bonsegna S.,Institute Of Science Of Food Production Cnr Unit Of Lecce | Lenucci M.S.,University of Salento | Poltronieri P.,Institute Of Science Of Food Production Cnr Unit Of Lecce | And 2 more authors.
Journal of Integrative Plant Biology | Year: 2011

Oleosin, caleosin and steroleosin are normally expressed in developing seed cells and are targeted to oil bodies. In the present work, the cDNA of each gene tagged with fluorescent proteins was transiently expressed into tobacco protoplasts and the fluorescent patterns observed by confocal laser scanning microscopy. Our results indicated clear differences in the endocellular localization of the three proteins. Oleosin and caleosin both share a common structure consisting of a central hydrophobic domain flanked by two hydrophilic domains and were correctly targeted to lipid droplets (LD), whereas steroleosin, characterized by an N-terminal oil body anchoring domain, was mainly retained in the endoplasmic reticulum (ER). Protoplast fractionation on sucrose gradients indicated that both oleosin and caleosin-green fluorescent protein (GFP) peaked at different fractions than where steroleosin-GFP or the ER marker binding immunoglobulin protein (BiP), were recovered. Chemical analysis confirmed the presence of triacylglycerols in one of the fractions where oleosin-GFP was recovered. Finally, only oleosin- and caleosin-GFP were able to reconstitute artificial oil bodies in the presence of triacylglycerols and phospholipids. Taken together, our results pointed out for the first time that leaf LDs can be separated by the ER and both oleosin or caleosin are selectively targeted due to the existence of selective mechanisms controlling protein association with these organelles. © 2011 Institute of Botany, Chinese Academy of Sciences.

Santino A.,Institute Of Science Of Food Production Cnr Unit Of Lecce | Taurino M.,Institute Of Science Of Food Production Cnr Unit Of Lecce | De Domenico S.,Institute Of Science Of Food Production Cnr Unit Of Lecce | Bonsegna S.,Institute Of Science Of Food Production Cnr Unit Of Lecce | And 3 more authors.
Plant Cell Reports | Year: 2013

Plants frequently live in environments characterized by the presence of simultaneous and different stresses. The intricate and finely tuned molecular mechanisms activated by plants in response to abiotic and biotic environmental factors are not well understood, and less is known about the integrative signals and convergence points activated by plants in response to multiple (a)biotic stresses. Phytohormones play a key role in plant development and response to (a)biotic stresses. Among these, one of the most important signaling molecules is an oxylipin, the plant hormone jasmonic acid. Oxylipins are derived from oxygenation of polyunsaturated fatty acids. Jasmonic acid and its volatile derivative methyl jasmonate have been considered for a long time to be the bioactive forms due to their physiological effects and abundance in the plant. However, more recent studies showed unambiguously that they are only precursors of the active forms represented by some amino acid conjugates. Upon developmental or environmental stimuli, jasmonates are synthesized and accumulate transiently. Upon perception, jasmonate signal transduction process is finely tuned by a complex mechanism comprising specific repressor proteins which in turn control a number of transcription factors regulating the expression of jasmonate responsive genes. We discuss the latest discoveries about the role of jasmonates in plants resistance mechanism against biotic and abiotic stresses. Finally, the deep interplay of different phytohormones in stresses signaling will be also discussed. © 2013 Springer-Verlag Berlin Heidelberg.

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