Engagement of T cell receptor triggers its recruitment to low-density detergent-insoluble membrane domains

T-cell receptors (TCRs) upon binding to peptide-MHC ligands transduce signals in T lymphocytes. Tyrosine phosphorylations in the cytoplasmic domains of the CD3 (gammadeltaepsilon) and zeta subunits of the TCR complex by Src family kinases initiate the signaling cascades via docking and activation of ZAP-70 kinase and other signaling components. We examined the role of the low-density detergent-insoluble membranes (DIMs) in TCR signaling. Using mouse thymocytes as a model, we characterized the structural organization of DIMs in detail. We then demonstrated that TCR engagement triggered an immediate increase in the amount of TCR/CD3 present in DIMs, which directly involves the engaged receptor complexes. TCR/CD3 recruitment is accompanied by the accumulation of a series of prominent tyrosine-phosphorylated substrates and by an increase of the Lck activity in DIMs. Upon TCR stimulation, the DIM-associated receptor complexes are highly enriched in the hyperphosphorylated p23 zeta chains, contain most of the TCR/CD3-associated, phosphorylation-activated ZAP-70 kinases and seem to integrate into higher order, multiple tyrosine-phosphorylated substrate-containing protein complexes. The TCR/CD3 recruitment was found to depend on the activity of Src family kinases. We thus provide the first demonstration of recuitment of TCR/CD3 to DIMs upon receptor stimulation and propose it as a mechanism whereby TCR engagement is coupled to downstream signaling cascades.     

On the time-domain scattering by a passive classical frequency dependent wedge-shaped region in a lossy dispersive medium

The time-scattering of an electromagnetic wave by a wedge-shaped region in a lossy medium, both with frequency dependent electric characteristics, is analyzed for plane wave and line source illuminations. New exact analytical expressions, satisfying explicitely the causality and allowing useful physical decompositions of the field, are obtained in these cases, using the particularities of the harmonic response in Sommerfeld-Maliuzhinets integral, especially original properties of the spectral function attached to it.     

A New Criteria Decision Applied on the Primary Synchronization in the DS-WCDMA Interface of the UMTS System

In DS-WCDMA mobile systems such the UMTS, asynchronous cell site operation,assigning different long spreading code to each cell, yields the advantageof flexible system deployment. We can design an indoor system basedon an outdoor one. However, in general, much longer search time isrequired in asynchronous operation than in synchronous. This paperproposes three techniques to take decisions about synchronizationbased on observation of correlated signals. Classical decision criterialike maximum and threshold criterion are presented. A new decisioncriteria that we call Threshold&Max combined decision criteriais analyzed. The results of this new introduced technique is comparedwith the classical ones.     

Positional distribution of fatty acids in cardiolipin of mitochondria from 21-day-old rats

Pure cardiolipins (1,3-diphosphatidylglycerol) were prepared from mitochondria of heart, liver and kidney from 21-day-old male Wistar rats and submitted toNaja naja venom phospholipase A₂ (EC 3.1.1.4) action. Incubation conditions were controlled carefully, and a complete hydrolysis of cardiolipin to lysocardiolipin {di [1 (1″) acylsn-glycero-3-phosphoryl] 1′, 3′-sn-glycerol} and fatty acids from positions 2 (2″) was obtained in less than two hr practically without side reactions. Cardiolipins from the three organs contained low levels of saturated fatty acids; stearic acid accounted for 0.4–0.7% and palmitic acid for 1.4–3.5% of total fatty acids. These percentages apparently depended on the organ. In all three cases, linoleic acid was the major component, but its percentage varied from 62–78% of total fatty acids. Acyl chains linked to positions 1 (1″) of all three cardiolipin preparations exhibited a similar pattern; they were composed of linoleic acid for 85–89%. This fatty acid also was the main component esterified at position 2 (2″), but its percentage was much more variable: from 39.8% in heart to 51.2% in kidney and 67.8% in liver mitochondria. The remaining acids comprised octadecenoic and polyunsaturated fatty acids with more than 18 carbon atoms in different proportions. As opposed to other phospholipids,cis-vaccenic acid, and not oleic acid, was the main octadecenoic acid present in cardiolipins. Octadecenoic acids were nine- to 10-fold more concentrated at positions 2 (2″) than at positions 1 (1″). The percentage ofcis-vaccenic acid was four- to five-fold higher than that of oleic acid at positions 2 (2″), whereas oleic acid dominated at positions 1 (1″). From results presented in this study and selected literature data, it may be concluded that fatty acids are asymmetrically distributed in cardiolipins of different origins, with linoleic acid showing a definite preference for position 1 (1″).     

Primitives for distributed computing in a heterogeneous local areanetwork environment

Epsilon is a testbed for monitoring distributed applications involving heterogeneous computers, including microcomputers, interconnected by a local area network. Such a hardware configuration is usual but raises difficulties for the programmer. First, the interprocess communication mechanisms provided by the operating systems are rather cumbersome to use. Second, they are different from one system to another. Third, the programmer of distributed applications should not worry about system and/or network aspects that are not relevant for the application level. The authors present the solution chosen in Epsilon. A set of high-level communication primitives has been designed and implemented to provide the programmer with an interface independent of the operating system and of the underlying interprocess communications facilities. A program participating in a distributed application can be executed on any host without any change in the source code except for host names     

Lessons learnt from 15 years of ICA in anaerobic digesters.

Anaerobic digestion plants are highly efficient wastewater treatment processes with inherent energy production. Despite these advantages, many industries are still reluctant to use them because of their instability confronted with changes in operating conditions. There is therefore great potential for application of instrumentation, control and automation (ICA) in the field of anaerobic digestion. This paper will discuss the requirements (in terms of on-line sensors needed, modelling efforts and mathematical complexity) but also the advantages and drawbacks of different control strategies that have been applied to AD high rate processes over the last 15 years.