Do glycerolipids display lateral heterogeneity in the thylakoid membrane?

The lateral heterogeneity of lipids in the thylakoid membrane has been questioned for over 20 yrs. It is generally believed that glycerolipids are asymmetrically distributed within the plane of the membrane. In the present investigation, we isolated several thylakoid membrane domains by using sonication followed by separation in an aqueous dextran-polyethylene glycol two-phase system. This technique, which avoids detergent treatments, allowed us to obtain stroma and grana lamellae vesicles as well as grana central core and grana margin vesicles from thylakoids. The relative distribution of the four lipid classes, i.e., monogalactosyldiacylglycerol, digalactosyldiacylglycerol, sulfoquinovosyldiacylglycerol, and phosphatidylglycerol, was found to be statistically identical in all four thylakoid fractions and in whole thylakoids. Similarly, the relative amount of fatty acids in each individual lipid and the eight main phosphatidylglycerol molecular species was identical in all thylakoid membrane fractions tested as well as in the intact thylakoid membrane. Based on presently available procedures for obtaining thylakoid subfractions that are unable to discriminate microdomains within the membrane, it is concluded that glycerolipids are evenly distributed within the plane of the thylakoid membrane. These data are discussed in terms of “bulk” and “specific” lipids.     

The characterization of continuous hot-dip galvanized and galvannealed steels

The use of zinc-coated steels for automotive, construction, and appliance applications has grown continually during the past decade. An understanding of the effects of process parameters and substrate characteristics on the coating microstructure is critical for optimizing the performance of the zinc-based coatings. This paper presents an overview of the application of advanced electron and focused-ion-beam microscopy techniques to characterize the microstructure of galvanized and galvannealed coatings.     

Lorsque la stratégie du grain de sable et la conformité aux normes freinent ľinnovation

For a company, information and communication system is a product of divergent rationalities which come to clash. Dissimilar logic leads to diverging projects : one focused on information aims to integrate and control its processing and flow rate, the other prefers to look at communication as a vector of working together among peers. However beyond these conflicts appears a factor of coherence and cohesion which ultimately helps the rationalities to join. A management able to combine integration of wage earners by identifying the objectives of the company and individualism (information systems is a vector of such a strategy). The goal is to avoid a major risk in form of mass action. The remaining question turns about the ability for innovation allowed to wage-earners in a company driven by standards and believes, in fact ideology. Sticking to standards, in other words conformity seems to leave out marginal handling and conflicting situation sources of innovative spirit.     

Development of novel 1,2,3,4-tetrahydroisoquinoline derivatives and closely related compounds as potent and selective dopamine D3 receptor ligands

Based on N-alkylated 1,2,3,4-tetrahydroisoquinoline derivatives, which are structurally related to the partial agonist BP 897, a series of novel, selective dopamine D3 receptor antagonists has been synthesised. Derivatisation included changes in the arylamide moiety and the tetrahydroisoquinoline substructure leading to compounds with markedly improved selectivities and affinities in the low nanomolar concentration range. From the 55 structures presented here, (E)-3-(4-iodophenyl)-N-(4-(1,2,3,4-tetrahydroisoquinolin-2-yl)butyl)acrylamide (51) has high affinity (Ki(hD3)=12 nM) and a 123-fold preference for the D3 receptor relative to the D2 receptor subtype. Its pharmacological profile offers the prospect of a novel radioligand as a tool for various dopamine D3-receptor-related in vitro and in vivo investigations.     

Structural diversity of sphingomyelin microdomains

In cells plasma membrane, sphingomyelin (SM) plays a key role in the formation of a category of lipid microdomains enriched in cholesterol (Chl) often referred to as rafts. Atomic force microscopy (AFM) was used to analyze the mesoscopic topography of enriched SM microdomains in supported bilayers made of SM/dioleoylphosphatidylcholine (SM/DOPC) and SM/palmitoyl-oleoyl-phosphatidylcholine (SM/POPC) equimolar mixtures, in buffer, at room temperature. Gel–fluid phase separation occurs in both SM/DOPC and SM/POPC bilayers. The gel phase SM-enriched microdomains adopt a variety of size, shape and mesoscopic structure, from homogeneous flat domains of a few hundreds of nanometer in diameter to domains of several micrometers made of closely packed globular structures. Gel–gel phase separation in SM domains is also observed which gives rise to different structures for the diunsaturated and the mixed-saturated PC species. These differences could also extend to the interactions with Chl. This suggests that studies on rafts formation commonly performed using SM/DOPC mixture as a model should also include the physiologically more relevant POPC species.     

Prevalence of Clostridium botulinum in food raw materials used in REPFEDs manufactured in France

Food raw materials used in refrigerated processed foods of extended durability (REPFEDs) manufactured in France were surveyed for Clostridium botulinum types A, B and E using PCR-Enzyme-linked Immunosorbent assay (PCR-ELISA) and mouse bioassay for detection respectively of cells and toxins in enrichment broth. Portions of 25 to 50 g of food were analysed. A total of 8 out of the 102 samples of fish and shellfish, 12 out of the 143 samples of meat and poultry, 1 out of the 62 samples of aroma, sauce and gravy, 4 out of the 25 samples of thickening agents, 3 out of the 26 samples of dehydrated dairy ingredients, and none of the 65 samples of spices, herbs and dehydrated mushroom were positive for C. botulinum in PCR-ELISA, i.e., 6.6% of all the samples tested. The 28 positive samples comprised 10 type A, 10 type B, 4 with both types A and B, and 4 undetermined by PCR typing. No sample positive for type E was detected. Of the 28 samples positive in PCR-ELISA, 15 were also positive in the mouse bioassay. The MPN count was between 1 and 3 C. botulinum/kg of food, which is similar to or in the lower range of values reported in the literature.     

An inquiry of the opinions of the French and Belgian populations as regards risk

IRSN (France) and SCK-CEN (Belgium), two institutes of research and expertise in radiation protection and nuclear safety, simultaneously organised a very similar public opinion survey in their respective countries in November 2002. The study explores subjects such as: major people's concerns, perception of environmental risks, perception of risks in general, the role of experts in decision making, opinions on nuclear matters and aspects of nuclear emergency preparedness. In each country, more than 1000 citizens representing the general public have been consulted in face-to-face interviews. The field work has been performed by professional companies (BVA in France and Research International in Belgium). The paper shows that industrial and technological risks are not perceived as one of the major public concerns, although many other risks, of different nature are considered to be high. The actions of the authorities to provide protection against the consequences of many risks or disasters are not considered to be sufficient, and many respondents claim not to believe the information they receive. There exists a large difference between the opinion of French and Belgian public, and within the different language groups in Belgium, with regard to who should be in charge of the control of the hazardous industries. Many of the "actors" within the nuclear industry are not known by the respondents. The perception of the technical competence or the truth being told shows large variations between the main actors (such as members of the nuclear industry, the government or the media). Majorities within the population believe that a disaster as serious as the Chernobyl one can happen in their country and that in case of a nuclear accident, the authorities would not be capable to protect the population adequately.     

Physiology in daily hemodialysis in terms of the time average concentration/time average deviation concept

Quotidian or “daily" hemodialysis (DHD) is practiced in widely differing schedules. Yet all those schedules are reported to significantly ameliorate clinical outcome of patients. It is, however, not clear what is the actual cause of this amelioration. Rational possibilities include increased overall dialysis dose and increased weekly time. Conventional mathematical approaches (Kt/V_urea concept, equivalent renal clearance) cannot be used to study those issues because they do not consider number of dialysis per week and thus ignore the issue of treatment schedule “unphysiology.” The time average concentration/time average deviation (TAC/TAD) concept may well be used to visualize impact of treatment schedule on both plasma urea profile statics (TAC) and dynamics (TAD). The concept may further help to stratify studies for elucidation of the key factors of clinical outcome improvement seen on DHD. Actual physiologic mechanisms responsible for this improvement are to be sought among those with having derivative component (i.e., reacting to the rate of a change rather than to the magnitude of the change). It should, however, be kept in mind that the TAC/TAD concept is able to assess unphysiology of a treatment schedule, not unphysiology of a single treatment session.     

Properties of two’s complement floating point notations

Few designs, mostly those of Texas Instruments, continue to use twos complement floating point units. Such units are simpler to build and to validate, but they do not comply to the dominant IEEE standard for floating point arithmetic. We compare some properties of the two systems in this text. Some features are lost, but others remain unchanged. One strong example is the case of Sterbenzs theorem and our recent extension. We show in the paper that the theorem and its extension hold for the twos complement architecture. Still, users should ensure that results are large enough on circuits that do not implement gradual underflow. Theorems have been proven and validated using the Coq automatic proof checker.