Seasonal variability of picophytoplankton under contrasting environments in northern Tunisian coasts, southwestern Mediterranean Sea.

We investigated at the single cell level during 16months (June 2012 to September 2013) the temporal distribution of picophytoplankton (picoeukaryotes, Synechococcus and Prochlorococcus) communities in two contrasted ecosystems: the Bay of Bizerte characterised by an oligotrophic regime typical of the Mediterranean Sea and the Bizerte Lagoon that exhibits a mesotrophic/eutrophic state. We aimed at depicting seasonal variations and quantifying the relationships between the environmental factors and the structure and abundance of picophytoplankton communities. Results showed that picophytoplankton groups were able to grow under a wide range of environmental conditions varying seasonally, although their abundances and contributions to the total chlorophyll biomass significantly varied and showed importance in the Bay of Bizerte. Synechococcus was the most abundant group reaching 225∗103cells·cm-3 in the Bay and 278∗103cells·cm-3 in the lagoon. This group was present all over the year in both ecosystems. Structural equation model results pointed out a different configuration regarding the picophytoplankton environmental drivers. The complexity of the configuration, i.e. number of significant links within the system, decreased under enhanced eutrophication conditions. The less exposure to anthropogenic stress, i.e. in the Bay of Bizerte, highlight a larger role of nutrient and hydrological conditions on the seasonal variations of picophytoplankton, whereas a negative effect of eutrophication on picophytoplankton communities was unveiled in the Bizerte Lagoon. We stress that such influence may be exacerbated under expected scenarios of Mediterranean warming conditions and nutrient release in coastal ecosystems.

[Time for implementation of hypolipemiant treatment in patient with dyslipidemia in general medicine: results of the Prysme study]. / Délai d'instauration d'un traitement hypolipémiant chez des patients présentant une dyslipidémie en médecine générale : résultats de l'enquête Prysme.

INTRODUCTION: Despite of specific guidelines regarding the treatment of dyslipidemia, therapeutic management of patients is not optimal. The objectives of this study were to describe the time for implementation of hypolipemiant treatment and to identify the determinants. METHODS: This was an observational, transversal, prospective, multicenter study carried out in France by general practitioners. Adult patients with dyslipidemia diagnosed since<2 years were eligible for this study. Demographic, diagnosis and disease characteristics, and treatment procedures were collected. RESULTS: Three thousand six hundred and twenty-four patients were enrolled by 1226 physicians, and data from 3268 patients meeting the selection criteria were analyzed. Mean age was 57 years old, 64% were male. More than 45% of the patients were overweight, 26% were obese. Only 12% of the patients had no cardiovascular risk factor at the time of dyslipidemia diagnosis. The most frequent cardiovascular risk factors consisted in arterial hypertension (50%), smoking (43%), family antecedents of coronary disease (28%), HDL-cholesterol less than 0.4g/L (20%); 15% of the patients had personal antecedents of cardiovascular disease. Initial management of dyslipidemia included implementation of lifestyle changes for 98% of the patients. More than 90% of the patients were treated with a statin. The median time for implementation of hypolipemiant treatment was 2.9 months. The hypolipemiant treatment was initiated more than 3 months after dyslipidemia diagnosis for 43% of the patients. The main determinant factor of an early implementation of hypolipemiant treatment (≤3 months) was secondary prevention (OR=2.2). The number of cardiovascular risk factors had no significant impact. CONCLUSION: This study highlights the lack of awareness towards the number of cardiovascular risk factors in the management of dyslipidemia, in primary prevention.

Shape and length of myosin heads.

There is controversy concerning the shape and length of myosin heads. In the present paper we try to analyse the data and to draw clear conclusions in this field. When the myosin heads are isolated (S1) from the rest of the molecule, their length is approximately 12 nm and their shape is close to that of a prolate ellipsoid with an axial ratio approximately 2.3 (in solution) or close to that of a comma when attached to F-actin (with a length of 12-13 nm). When the myosin heads are observed on a whole molecule, their length is approximately 19 nm and they are pear-shaped. Here we suggest that all these observations are compatible. We believe that, for a whole myosin molecule, a large part of the head-rod joint (S1/S2 joint) is measured with the head, owing to a particularly heavy staining or shadowing of this joint. On the other hand, S1 is probably built up of a head part plus the S1/S2 joint, which is not revealed by the usual techniques (hydrodynamics, X-ray and neutron scattering). Finally, the comma shape would be related to a flexible part in the head region of S1, which is significantly bent when S1 is attached to F-actin, but which would be less bent for S1 in solution. A similar bending also occurs in crystalline S1.