Type-1 Cannabinoid Receptors Reduce Membrane Fluidity of Capacitated Boar Sperm by Impairing Their Activation by Bicarbonate

Background Mammalian spermatozoa acquire their full fertilizing ability (so called capacitation) within the female genital tract, where they are progressively exposed to inverse gradients of inhibiting and stimulating molecules. Methodology/Principal Findings In the present research, the effect on this process of anandamide, an endocannabinoid that can either activate or inhibit cannabinoid receptors depending on its concentration, and bicarbonate, an oviductal activatory molecule, was assessed, in order to study the role exerted by the type 1 cannabinoid receptor (CB1R) in the process of lipid membrane remodeling crucial to complete capacitation. To this aim, boar sperm were incubated in vitro under capacitating conditions (stimulated by bicarbonate) in the presence or in the absence of methanandamide (Met-AEA), a non-hydrolysable analogue of anandamide. The CB1R involvement was studied by using the specific inhibitor (SR141716) or mimicking its activation by adding a permeable cAMP analogue (8Br-cAMP). By an immunocytochemistry approach it was shown that the Met-AEA inhibits the bicarbonate-dependent translocation of CB1R from the post-equatorial to equatorial region of sperm head. In addition it was found that Met-AEA is able to prevent the bicarbonate-induced increase in membrane disorder and the cholesterol extraction, both preliminary to capacitation, acting through a CB1R-cAMP mediated pathway, as indicated by MC540 and filipin staining, EPR spectroscopy and biochemical analysis on whole membranes (CB1R activity) and on membrane enriched fraction (C/P content and anisotropy). Conclusions/Significance Altogether, these data demonstrate that the endocannabinoid system strongly inhibits the process of sperm capacitation, acting as membrane stabilizing agent, thus increasing the basic knowledge on capacitation-related signaling and potentially opening new perspectives in diagnostics and therapeutics of male infertility

Semaphorin, neuropilin and VEGF expression in glial tumours: SEMA3G, a prognostic marker?

Gliomas are characterised by local infiltration, migration of tumour cells across long distances and sustained angiogenesis; therefore, proteins involved in these processes are most likely important. Such candidates are semaphorins involved in axon guidance and cell migration. In addition, semaphorins regulate tumour progression and angiogenesis. For cell signalling, class-4 semaphorins bind directly to plexins, whereas class-3 semaphorins require additional neuropilin (NRP) receptors that also bind VEGF165. The anti-angiogenic activity of class-3 semaphorins can be explained by competition with VEGF165 for NRP binding. In this study, we analysed the expressions of seven semaphorins of class-3, SEMA4D, VEGF and the NRP1 and NRP2 receptors in 38 adult glial tumours. In these tumours, SEMA3B, SEMA3G and NRP2 expressions were related to prolonged survival. In addition, SEMA3D expression was reduced in high-grade as compared with low-grade gliomas. In contrast, VEGF correlated with higher grade and poor survival. Thus, our data suggest a function for a subset of class-3 semaphorins as inhibitors of tumour progression, and the prognostic value of the VEGF/SEMA3 balance in adult gliomas. Moreover, in multivariate analysis, SEMA3G was found to be the only significant prognostic marker

Une nouvelle race de Parnassius apollo Linné : P. apollo race ossalensis Mihi

Marquant R.-M. Une nouvelle race de Parnassius apollo Linné : P. apollo race ossalensis Mihi. In: Bulletin mensuel de la Société linnéenne de Lyon, 28ᵉ année, n°2, février 1959. pp. 51-52

Participation à la connaissance des Parnassiinae français. A propos de Parnassius apollo vercorius Testout

Marquant R.-M. Participation à la connaissance des Parnassiinae français. A propos de Parnassius apollo vercorius Testout. In: Bulletin mensuel de la Société linnéenne de Lyon, 29ᵉ année, n°10, décembre 1960. pp. 289-290

Influence of slip on the Rayleigh-plateau rim instability in dewetting viscous films

A dewetting viscous film develops a characteristic fluid rim at its receding edge due to mass conservation. In the course of the dewetting process, the rim becomes unstable via an instability of Rayleigh-Plateau type. An important difference exists between this classic instability of a liquid column and the rim instability in a thin film as the growth of the rim is continuously fueled by the receding film. We explain how the development and macroscopic morphology of the rim instability are controlled by the slip of the film on the substrate. A single thin-film model captures quantitatively the characteristics of the complete evolution of the rim observed in the experiments

Influence of slip on the Rayleigh-Plateau rim instability in dewetting viscous films.

A dewetting viscous film develops a characteristic fluid rim at its receding edge due to mass conservation. In the course of the dewetting process, the rim becomes unstable via an instability of Rayleigh-Plateau type. An important difference exists between this classic instability of a liquid column and the rim instability in a thin film as the growth of the rim is continuously fueled by the receding film. We explain how the development and macroscopic morphology of the rim instability are controlled by the slip of the film on the substrate. A single thin-film model captures quantitatively the characteristics of the complete evolution of the rim observed in the experiments