Structural insights into the membrane-extracted dimeric form of the ATPase TraB from the Escherichia coli pKM101 conjugation system

Background: Type IV secretion (T4S) systems are involved in secretion of virulence factors such as toxins or transforming molecules, or bacterial conjugation. T4S systems are composed of 12 proteins named VirB1-B11 and VirD4. Among them, three ATPases are involved in the assembly of the T4S system and/or provide energy for substrate transfer, VirB4, VirB11 and VirD4. The X-ray crystal structures of VirB11 and VirD4 have already been solved but VirB4 has proven to be reluctant to any structural investigation so far. Results: Here, we have used small-angle X-ray scattering to obtain the first structural models for the membrane-extracted, dimeric form of the TraB protein, the VirB4 homolog encoded by the E. coli pKM101 plasmid, and for the monomeric soluble form of the LvhB4 protein, the VirB4 homolog of the T4S system encoded by the Legionella pneumophila lvh operon. We have obtained the low resolution structures of the full-length TraB and of its N- and C-terminal halves. From these SAXS models, we derive the internal organisation of TraB. We also show that the two TraB N- and C-terminal domains are independently involved in the dimerisation of the full-length protein. Conclusions: These models provide the first structural insights into the architecture of VirB4 proteins. In particular, our results highlight the modular arrangement and functional relevance of the dimeric-membrane-bound form of TraB

Effects of MCH and a MCH1-receptor antagonist on (palatable) food and water intake

Melanin concentrating hormone (MCH) is a regulator of ingestive behavior, but several issues regarding its effects on specific components of ingestive behavior remain to be elucidated. Therefore, we injected, in the 3rd ventricle of male Wistar rats, saline, MCH (5 mu g), MCH (5 mu g) together with a MCH1-R antagonist (A, 10 mu g) and the antagonist alone (A, 10 mu g). Our results show that (1) central administration of MCH stimulates food intake (lab chow and medium high fat diet) and this can be blocked by a MCH1-R antagonist; (2) the MCH-induced increase in food intake is mediated through increased meal number, meal duration and meal size; (3) the MCH1-R antagonist is able to significantly reduce the intake of a highly palatable food (condensed sweet milk) and is more effective in blocking MCH-induced food intake when rats are fed a palatable medium high fat food; and (4) MCH stimulated water intake independently from and disproportionately to food intake. In conclusion, our results point to an involvement of endogenous MCH in the enhanced intake of palatable food. Furthermore, they confirm that MCH stimulates not only food intake but also water intake. (c) 2005 Elsevier B.V. All rights reserved

Cardiometabolic Risk Factors and Associated Features in 5th Grade Schoolchildren in Ouagadougou, Burkina Faso (West Africa)

The onset of cardiometabolic risk factors in childhood may be tracked into adulthood. However, little is known about such risk factors particularly in African schoolchildren. We conducted in Ouagadougou the capital city of Burkina Faso (West Africa) a cross-sectional study in 5th grade pupils of 12 schools (4 private and 8 public of which 2 were periurban). Weight, height, and blood pressure (BP) were measured and fasting serum lipids and glycaemia were determined. Sample mean age was 11.8 ±1.4 y (207 children, 51% girls). Mean total cholesterol (TC), LDL-C, HDL-C and triglycerides were 133.9, 83.5, 45.1 and 67.1 mg/dl, respectively; glycaemia stood at 87.9 ±7.1 mg/dl. Systolic (SBP) and Diastolic Blood Pressure (DBP) were 103.2 and 62.3 mmHg respectively. The main risk factor was low HDL-C (19.3%) followed by high TC and LDL-C (11.6% each). Elevated SBP and DBP were 9.7% and 4.3%, respectively. Being a girl was independently associated with increased serum lipids including HDL-C paradoxically. BMI was independently associated with increased BP. While attending a private school was independently associated (p<0.01) with higher HDL-C and lower TG and DBP, attending urban (vs periurban) school and higher age were independently associated with lower HDL-C. A sizeable proportion of children exhibited cardiometabolic risk factors and therefore, preventive measures would appear timely in low income country schoolchildren, and not only strategies targeting malnutrition

La dissimulation : instrumentalisation d'une notion au service d'une politique répressive, note sous Cass. crim., 30 avril 2014, n° 13-82912, FD, D et a.Comm. 1411

La Chambre criminelle choisit une acception extensive de la dissimulation, dans sa dimension tant matérielle que temporelle, pour retarder le point de départ de la prescription de l'abus de biens sociaux, laquelle suscite cependant quelque inquiétude

L’effet partiellement exonératoire de la faute de la victime à l’égard du transporteur ferroviaire est encore d’actualité… en matière délictuelle !

La deuxième chambre civile ne souhaite vraisemblablement pas marcher sur les traces de la première chambre civile. Admettant le rôle partiellement exonératoire de la victime à l’égard du transporteur ferroviaire de personnes en matière délictuelle, elle corrobore en effet la rupture de régime entreprise en 2008 entre responsabilité délictuelle et contractuelle dont les conséquences apparaissent pour le moins regrettables. Aussi conviendrait-il d’uniformiser de nouveau le traitement juridique de la faute de la victime

De quelques spéculations sur l'amende civile en pays sociétaire

Article qui intègre l'étude que j'ai dirigée sur Les éventuelles évolutions de la responsabilité civile et le droit des entreprise