Real Field Deployment of a Smart Fiber Optic Surveillance System for Pipeline Integrity Threat Detection: Architectural Issues and Blind Field Test Results

This paper presents an on-line augmented surveillance system that aims to real time monitoring of activities along a pipeline. The system is deployed in a fully realistic scenario and exposed to real activities carried out in unknown places at unknown times within a given test time interval (socalled blind field tests). We describe the system architecture that includes specific modules to deal with the fact that continuous on-line monitoring needs to be carried out, while addressing the need of limiting the false alarms at reasonable rates. To the best or our knowledge, this is the first published work in which a pipeline integrity threat detection system is deployed in a realistic scenario (using a fiber optic along an active gas pipeline) and is thoroughly and objectively evaluated in realistic blind conditions. The system integrates two operation modes: The machine+activity identification mode identifies the machine that is carrying out a certain activity along the pipeline, and the threat detection mode directly identifies if the activity along the pipeline is a threat or not. The blind field tests are carried out in two different pipeline sections: The first section corresponds to the case where the sensor is close to the sensed area, while the second one places the sensed area about 35 km far from the sensor. Results of the machine+activity identification mode showed an average machine+activity classification rate of 46:6%. For the threat detection mode, 8 out of 10 threats were correctly detected, with only 1 false alarm appearing in a 55:5-hour sensed period.European CommissionMinisterio de Economía y CompetitividadComunidad de Madri

Mechanisms regulating the acyl chain composition of membrane lipids in S. cerevisiae

The goal of the research described in this thesis was to identify the genes/enzymes involved in acyl chain remodeling of the major membrane lipid phosphatidylcholine (PC) in the model eukaryote S. cerevisiae. A database search yielded 75 candidates with (potential) phospholipase, acyltransferase or transacylase activity. The corresponding deletion strains were screened for the molecular species profiles of PC and phosphatidylethanolamine (PE), yielding 10 candidate strains. Using stable isotope labeling followed by analysis by mass spectrometry, the evolution of the species profile of PC newly synthesized via PE methylation was monitored in pulse-chase experiments, revealing that 6 strains displayed aberrant PC remodeling. Deletion of the SCT1/GAT2 gene coding for a glycerol-3-phosphate acyltransferase, led to the most pronounced change in PC remodeling. In-depth study into the role of Sct1p in regulating lipid acyl chain composition showed that Sct1p regulates fatty acyl chain desaturation, as deletion and overexpression of SCT1 dramatically change the acyl chain composition. We showed that it does so by competing with the fatty acid desaturase Ole1p for the common substrate C16:0-CoA in co-overexpression experiments of OLE1 and SCT1. A new paradigm for the regulation of fatty acid desaturation is presented in which an acyltransferase sequesters C16:0-CoA into lipids, thereby shielding it from desaturation by a fatty acid desaturase. Sct1p activity is regulated by phosphorylation. The level of Sct1p phosphorylation increases in response to the presence of C16:0 acyl chains in the culture medium, demonstrating the physiological relevance of these findings. Overexpression of Sct1p dramatically increases the cellular C16:0 content, and this excess C16:0 is incorporated into all glycerophospholipids: phosphatidic acid (PA), phosphatidylserine (PS), PE, PC, phosphatidylinositol (PI), phosphatidylglycerol (PG), and cardiolipin (CL). The extra C16:0 is incorporated into PC via both biosynthesis routes, and via enhanced remodeling. The increase in the extent of remodeling allowed a much more sensitive detection of PC acyl chain remodeling. Taking advantage of Sct1p overexpression we showed that remodeling occurs at both the sn-1 and sn-2 position of the glycerol backbone, and that the phospholipase B Plb1p is required for efficient remodeling. Plb2p and Lro1p were not required for PC acyl chain remodeling. Plb1p is the first enzyme that is shown to be directly involved in PC acyl chain remodeling, most probably by hydrolyzing both acyl chains. The role of PC as potential acyl donor of Taz1p, a CL remodeling transacylase, was also investigated. Analysis of the molecular species profiles of steady state and newly synthesized glycerophospholipids indicates that PS and/or PE rather than PC is the preferred acyl donor of Taz1p

Checks and balances in membrane phospholipid class and acyl chain homeostasis, the yeast perspective

Glycerophospholipids are the most abundant membrane lipid constituents in most eukaryotic cells. As a consequence, phospholipid class and acyl chain homeostasis are crucial for maintaining optimal physical properties of membranes that in turn are crucial for membrane function. The topic of this review is our current understanding of membrane phospholipid homeostasis in the reference eukaryote Saccharomyces cerevisiae. After introducing the physical parameters of the membrane that are kept in optimal range, the properties of the major membrane phospholipids and their contributions to membrane structure and dynamics are summarized. Phospholipid metabolism and known mechanisms of regulation are discussed, including potential sensors for monitoring membrane physical properties. Special attention is paid to processes that maintain the phospholipid class specific molecular species profiles, and to the interplay between phospholipid class and acyl chain composition when yeast membrane lipid homeostasis is challenged. Based on the reviewed studies, molecular species selectivity of the lipid metabolic enzymes, and mass action in acyl-CoA metabolism are put forward as important intrinsic contributors to membrane lipid homeostasis

Checks and balances in membrane phospholipid class and acyl chain homeostasis, the yeast perspective

Glycerophospholipids are the most abundant membrane lipid constituents in most eukaryotic cells. As a consequence, phospholipid class and acyl chain homeostasis are crucial for maintaining optimal physical properties of membranes that in turn are crucial for membrane function. The topic of this review is our current understanding of membrane phospholipid homeostasis in the reference eukaryote Saccharomyces cerevisiae. After introducing the physical parameters of the membrane that are kept in optimal range, the properties of the major membrane phospholipids and their contributions to membrane structure and dynamics are summarized. Phospholipid metabolism and known mechanisms of regulation are discussed, including potential sensors for monitoring membrane physical properties. Special attention is paid to processes that maintain the phospholipid class specific molecular species profiles, and to the interplay between phospholipid class and acyl chain composition when yeast membrane lipid homeostasis is challenged. Based on the reviewed studies, molecular species selectivity of the lipid metabolic enzymes, and mass action in acyl-CoA metabolism are put forward as important intrinsic contributors to membrane lipid homeostasis

The yeast acyltransferase Sct1p regulates fatty acid desaturation by competing with the desaturase Ole1p.

The degree of fatty acid unsaturation, that is, the ratio of unsaturated versus saturated fatty acyl chains, determines membrane fluidity. Regulation of expression of the fatty acid desaturase Ole1p was hitherto the only known mechanism governing the degree of fatty acid unsaturation in Saccharomyces cerevisiae. We report a novel mechanism for the regulation of fatty acid desaturation that is based on competition between Ole1p and the glycerol-3-phosphate acyltransferase Sct1p/Gat2p for the common substrate C16:0-CoA. Deletion of SCT1 decreases the content of saturated fatty acids, whereas overexpression of SCT1 dramatically decreases the desaturation of fatty acids and affects phospholipid composition. Whereas overexpression of Ole1p increases desaturation, co-overexpression of Ole1p and Sct1p results in a fatty acid composition intermediate between those obtained upon overexpression of the enzymes separately. On the basis of these results, we propose that Sct1p sequesters C16:0-CoA into lipids, thereby shielding it from desaturation by Ole1p. Ta-king advantage of the growth defect conferred by overexpressing SCT1, we identified the acyltransferase Cst26p/Psi1p as a regulator of Sct1p activity by affecting the phosphorylation state and overexpression level of Sct1p. The level of Sct1p phosphorylation is increased when cells are supplemented with saturated fatty acids, demonstrating the physiological relevance of our findings

Syntheses of alkenylated carbohydrate derivatives toward the preparation of monolayers on silicon surfaces

This note describes the synthesis of different alkenylated carbohydrate derivatives suitable for direct attachment to hydrogen-terminated silicon surfaces. The derivatives were alkenylated at the C-1 position, while the remaining hydroxyl groups were protected. The development of such new carbohydrate-based sensing elements opens the access to new classes of biosensor

Early detection of pipeline integrity threats using a SmarT Fiber- OPtic surveillance system: The PIT-STOP project

24th International Conference on Optical Fibre Sensors, Curitiba, Brazil, September 28, 2015The preliminary results of a surveillance system set up for real time monitoring activities along a pipeline and analyzing for possible threats are presented. The system consists of a phi-OTDR based sensor used to monitor vibrations along an optical fiber combined with a pattern recognition system that classifies the recorded signals. The acoustic traces generated by the activities of different machines at various locations along a pipeline were recorded in the field. The signals, corresponding to machinery activities, were clearly distinguished from background noise. A threat classification rate of 68.11% with 55.55% false alarms was obtained