On the interactions of lipids and proteins in the red blood cell membrane

The effects of temperature and of the action of a purified phospholipase C enzyme preparation on human red blood cell membranes has been investigated by chemical analyses, circular dichroism, and proton magnetic resonance measurements. The results indicate that a substantial fraction of the phospholipids and the proteins of the membranes can change structure independently of one another, suggesting a mosaic pattern for the organization of the lipids and proteins in membranes

Differentiation and Dynamics of Competitiveness Impacts from the EU ETS

We summarise the main factors that differentiate impacts of the EU ETS on profitability and market share. By examining and sampling a range of sectors, we present some simple metrics and indicators to help judge the nature of potential impacts. We also consider briefly the mitigation response to these impacts by sectors, and how they may evolve over time. The broad conclusion confirms the aggregate findings presented in the existing literature - more participating sectors are likely to profit under the current ETS structure out to 2012 at the cost of a modest loss of market share, but this may not hold for individual companies and regions. The period 2008-12 can assist technology investments and diversification, providing the continuation and basic principles of the EU ETS post-2012 is quickly defined and incentives are in place for sectors to pursue this

Striped spin liquid crystal ground state instability of kagome antiferromagnets

The Dirac spin liquid ground state of the spin 1/2 Heisenberg kagome antiferromagnet has potential instabilities[1-4]. This has been suggested as the reason why it is not strongly supported in large-scale numerical calculations[5]. However, previous attempts to observe these instabilities have failed. We report on the discovery of a projected BCS state with lower energy than the projected Dirac spin liquid state which provides new insight into the stability of the ground state of the kagome antiferromagnet. The new state has three remarkable features. First, it breaks both spatial symmetry in an unusual way that may leave spinons deconfined along one direction. Second, it breaks the U(1) gauge symmetry down to $Z_2$. Third, it has the spatial symmetry of a previously proposed "monopole" suggesting that it is an instability of the Dirac spin liquid. The state described herein also shares a remarkable similarity to the distortion of the kagome lattice observed at low Zn concentrations in Zn-Paratacamite suggesting it may already be realized in these materials.Comment: 4+ pages, 3 figure

Halide binding by the purified halorhodopsin chromoprotein. II. New chloride-binding sites revealed by 35Cl NMR

Halorhodopsin is a light-driven chloride pump in the cell membrane of Halobacterium halobium. Recently, a polypeptide of apparent Mr = 20,000 has been purified that contains the halorhodopsin chromophore. Here we use 35Cl NMR to show that the purified chromoprotein possesses two previously unknown classes of chloride-binding sites. One class exhibits a low affinity (KD much greater than 1 M) for chloride and bromide. The second class exhibits a higher affinity (KD = 110 ± 50 mM) for chloride and also binds other anions according to the affinity series I-, SCN- greater than Br-, NO-3 greater than Cl- greater than F- , citrate. Both classes of NMR site remain intact at pH 11, indicating that the essential positive charges are provided by arginine. Also, both classes are unaffected by bleaching, suggesting that the sites are not in the immediate vicinity of the halorhodopsin chromophore. Although the chromoprotein also appears to contain the chloride- transport site (Steiner, M., Oesterhelt, D., Ariki, M., and Lanyi, J. K. (1984) J. Biol. Chem. 259, 2179-2184), this site was not detected by 35Cl NMR, suggesting that the transport site is in the interior of the protein where it is sampled slowly by chloride in the medium. It is proposed that the purified chromoprotein possesses a channel leading from the medium to the transport site and that the channel contains the high affinity NMR site which facilitates the migration of chloride between the medium and the transport site. We have also used 35Cl NMR to study chloride binding to purified monomeric bacteriorhodopsin; however, this protein contains no detectable chloride-binding sites

Mitofusins and OPA1 Mediate Sequential Steps in Mitochondrial Membrane Fusion

Mitochondrial fusion requires the coordinated fusion of the outer and inner membranes. Three large GTPases—OPA1 and the mitofusins Mfn1 and Mfn2—are essential for the fusion of mammalian mitochondria. OPA1 is mutated in dominant optic atrophy, a neurodegenerative disease of the optic nerve. In yeast, the OPA1 ortholog Mgm1 is required for inner membrane fusion in vitro; nevertheless, yeast lacking Mgm1 show neither outer nor inner membrane fusion in vivo, because of the tight coupling between these two processes. We find that outer membrane fusion can be readily visualized in OPA1-null mouse cells in vivo, but these events do not progress to inner membrane fusion. Similar defects are found in cells lacking prohibitins, which are required for proper OPA1 processing. In contrast, double Mfn-null cells show neither outer nor inner membrane fusion. Mitochondria in OPA1-null cells often contain multiple matrix compartments bounded together by a single outer membrane, consistent with uncoupling of outer versus inner membrane fusion. In addition, unlike mitofusins and yeast Mgm1, OPA1 is not required on adjacent mitochondria to mediate membrane fusion. These results indicate that mammalian mitofusins and OPA1 mediate distinct sequential fusion steps that are readily uncoupled, in contrast to the situation in yeast

On the Corner Elements of the CKM and PMNS Matrices

Recent experiments show that the top-right corner element ($U_{e3}$) of the PMNS, like that ($V_{ub}$) of the CKM, matrix is small but nonzero, and suggest further via unitarity that it is smaller than the bottom-left corner element ($U_{\tau 1}$), again as in the CKM case ($V_{ub} < V_{td}$). An attempt in explaining these facts would seem an excellent test for any model of the mixing phenomenon. Here, it is shown that if to the assumption of a universal rank-one mass matrix, long favoured by phenomenologists, one adds that this matrix rotates with scale, then it follows that (A) by inputting the mass ratios $m_c/m_t, m_s/m_b, m_\mu/m_\tau$, and $m_2/m_3$, (i) the corner elements are small but nonzero, (ii) $V_{ub} < V_{td}$, $U_{e 3} < U_{\tau 1}$, (iii) estimates result for the ratios $V_{ub}/V_{td}$ and $U_{e 3}/U_{\tau 1}$, and (B) by inputting further the experimental values of $V_{us}, V_{tb}$ and $U_{e2},U_{\mu 3}$, (iv) estimates result for the values of the corner elements themselves. All the inequalities and estimates obtained are consistent with present data to within expectation for the approximations made.Comment: 9 pages, 2 figures, updated with new experimental data and more detail

Mass Hierarchy, Mixing, CP-Violation and Higgs Decay---or Why Rotation is Good for Us

The idea of a rank-one rotating mass matrix (R2M2) is reviewed detailing how it leads to ready explanations both for the fermion mass hierarchy and for the distinctive mixing patterns between up and down fermion states, which can be and have been tested against experiment and shown to be fully consistent with existing data. Further, R2M2 is seen to offer, as by-products: (i) a new solution of the strong CP problem in QCD by linking the theta-angle there to the Kobayashi-Maskawa CP-violating phase in the CKM matrix, and (ii) some novel predictions of possible anomalies in Higgs decay observable in principle at the LHC. A special effort is made to answer some questions raised.Comment: 47 pages, 9 figure