Page 11

CIM29

N°29 I quarterly I Ap ril 2013 Live from the Labs | 11 w Cosmic Fog” The measurements of this fossil light agree with theoretical models of the formation and evolution of galaxies within a range of 20-30%. “More delicate adjustments between these models and data from high-energy gamma-ray observatories will no doubt hold more surprises,” adds Biteau. “In the context of current scientific knowledge, this is the first time we can predict and indirectly determine the entire visible light emitted during 95% of the universe’s lifespan.” 01. Laboratoire Leprince-Ringuet (CNRS / École polytechnique). 02. The HESS collaboration, “Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with HESS,” A&A, 2013. 550: A 4 Contact information: LLR , Palaiseau. Jonathan Biteau > biteau@llr.in2p3.fr from M48U1. Just one of the six macaques treated with the M48U1 gel was infected, compared to all six for the placebo. “These results demonstrate the inhibitive effect of M48U1 on sexual transmission of HIV,” adds Martin. “Fine tuning and clinical development will hopefully help develop new binding-inhibitory drugs as a complement to an effective vaccine.” 01. Institut de biologie et de technologies de Saclay (CEA / iBiTec-S). 02. N. Dereuddre-Bosquet et al., “MiniCD4 Microbicide Prevents HIV Infection of Human Mucosal Explants and Vaginal Transmission of SHIV162P3 in Cynomolgus Macaques,” PLOS Pathogens, 2012. 8:e1003071. Biophysics 3D Mapping of Lipid Orientation BY Edd y Delcher w A new method allowing for a noninvasive observation of the arrangement of lipid assemblies in intact biological tissues has just been published1 by French researchers at the LOB.2 Lipid assemblies, or fats, form an integral part of the body, where they play important roles, notably in the skin and nerves. “If skin surface cells are bricks, then lipid assemblies are the mortar that surrounds them and makes the skin an effective barrier. Lipid assemblies also form the insulating sheath around nerves,” explains Emmanuel Beaurepaire, who led the study. Disturbances in these assemblies’ molecular order often lead to severe pathologies. To investigate biological tissues at the subcellular scale, researchers often use multiphoton microscopy, a technique developed in the 1990s, in which laser illumination of fluorescent markers inserted in the tissue provides the necessary contrast to create a 3D map of the tagged structures. But inserting markers in patients or in live tissues is not always feasible or safe. “We have taken advantage of a natural optical property of lipid assemblies, called polarized third-harmonic generation (P-THG), to develop a new imaging method,” explains Beaurepaire. Indeed, lipid assemblies can convert a fraction of the laser light into another color, and the efficiency of this process varies with the polarization of the laser. It is this variation that provides information on the lipids’ molecular alignment. “Markers degrade and get diluted over time, and can modify lipids’ molecular order,” says Beaurepaire. “P-THG produces images at a much higher resolution than MRI and is therefore complementary. In addition, it is non-invasive and could one day find applications in medicine or medical research for early detection of diseases.” 01. Maxwell Zimmerley et al., “Probing ordered lipid assemblies with polarized third-harmonic generation microscopy,” Physical Review X, 2013. DOI: 10.1103/PhysRevX.3.011002. 02. Laboratoire d'optique et biosciences (CNRS / Inserm / École polytechnique). Contact information: CEA , Saclay. Loïc Martin > loic.martin@cea.fr Contact information: LO B, Palaiseau. Emmanuel Beaurepaire > emmanuel.beaurepaire@polytechnique.edu q P-THG mapping of molecular orientation in an amalgamation of multilamellar lipid vesicles. This virtual optical section, obtained without labeling, shows that the molecules are oriented perpendicularly at the interfaces. Palaiseau Palaiseau © École Pol ytechni que , CNRS, Inserm / Americ an Ph ysic al Societ y 50 μm


CIM29
To see the actual publication please follow the link above