Isolation and characterization of band 3, the predominant polypeptide of the human erythrocyte membrane.

Band 3 is the predominant approximately 90,000-dalton polypeptide component of the human erythrocyte membrane. It was solubilized selectively, along with the other major glycoproteins, by extracting membrane ghosts with Triton X-100 under nondenaturing conditions. Two major polypeptides remained associated with Band 3 under these conditions; however one (Band 6) could be dissociated at an ionic strength of 0.15 and the other (Band 4.2) by treatment with p-chloromercuribenzoate. Band 3 was then purified (greater than or equal to 97%) by aminoethyl cellulose ion exchange chromatography. The isolated protein was free of phospholipid and was moderately enriched in apolar amino acid residues; it contained galactose and glucosamine but very little sialic acid and galactosamine. When Band 3 was labeled by treatment of ghosts with galactose oxidase plus KB3H4 and then purified, the electrophoretic mobility of its radioactivity lagged slightly behing that of its Coomassie blue staining profile. Variation in glycosylation could therefore cause the diffuse trailing zone characteristically observed for Band 3 on polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The ultraviolet circular dichroism of Band 3 was stable in nonionic detergent and suggested an alpha helix content of 43%, a value close to that estimated for this polypeptide in the membrane.     

Interaction of flavins with electron-rich metals.

A complex of the electron-rich ion Cu(I) with the flavoquinone analogue 10-methylisoalloxazine has been synthesized and characterized by x-ray methods. The complex is unstable to oxygen. It is black-green in color, in contrast with the bright yellow, orange, or orange-brown crystalline complexes of 10-methylisoalloxazine or riboflavin with Cu(II), Ag(I), and Pb(II). These results are indicative of strong perturbation of the flavin electronic structure by the Cu(I) ion and suggest that this complex is a reasonable model for incipient transfer of an electron from a reduced metal to flavoquinone. the crystal structure is orthorhombic, Pna2-1, with unit cell constants a = 31.24(1) (figures in parentheses are estimated standard deviations), b = 12.862(4), c = 6.239(2) A, Pobs = 1.76 g per cm-3 and Pcalc = 1.77 g per cm-3 for Z = 4 and asymmetric formula CuClO4-2(C11H8N4O2). HCOOH. The final R factor based on 1250 counter-measured data is 8.8%. The 2 independent 10-methylisoalloxazine molecules, A and B, bind strongly to the cuprous ion throug N(5) of each flavin. The copper is approximately linearly coordinated with an N-Cu-N angle of 153(1) degrees, and Cu-N(5) distances of 1.94(2) A and 1.92(2) A. The next nearest atoms to Cu are the O(4) oxygens of each flavin, forming weak bonds with distances Cu-O(4) = 2.27(2) A and 2.21(2) A for molecules A and B. The dihedral angle between the 2 10-methylisoalloxazine molecules is 65.4 degrees.     

Nonsynaptic membrane of retinal horizontal cells as a slow potential amplifier

A simplified model of the membrane of horizontal cells of the L-type is designed to reflect two principal features of these cells previously studied experimentally: 1) their hyperpolarization response to light is the result of a decrease in the EPSP that is kept constant in darkness; 2) the resistance of their nonsynaptic membrane is reduced during hyperpolarization within physiological limits (from 0 to−70 mV). The model also reproduces properties of the horizontal cells such as the low membrane potential in darkness, reversal of the response to light during depolarization beyond the zero level, mutual amplification of color signals, saturation of the response to bright light, steady-state volt-ampere characteristics in darkness and light, and the amplitude characteristic curve which often has a steep part within a certain range of membrane potentials. The presence of hysteresis loops of the volt-ampere and amplitude characteristic curves of the horizontal cells predicted by the model was confirmed experimentally on the fish retina. Analysis of the model and results obtained with it show that the nonsynaptic membrane of the horizontal cells can actively amplify slow graded potentials.     

ZAKβ antagonizes and ameliorates the cardiac hypertrophic and apoptotic effects induced by ZAKα

ZAK (sterile alpha motif and leucine zipper containing kinase AZK), a serine/threonine kinase with multiple biochemical functions, has been associated with various cell processes, including cell proliferation, cell differentiation, and cardiac hypertrophy. In our previous reports, we found that the activation of ZAKα signaling was critical for cardiac hypertrophy. In this study, we show that the expression of ZAKα activated apoptosis through both a FAS‐dependent pathway and a mitochondria‐dependent pathway by subsequently inducing caspase‐3. ZAKβ, an isoform of ZAKα, is dramatically expressed during cardiac hypertrophy and apoptosis. The interaction between ZAKα and ZAKβ was demonstrated here using immunoprecipitation. The results show that ZAKβ has the ability to diminish the expression level of ZAKα. These findings reveal an inherent regulatory role of ZAKβ to antagonize ZAKα and to subsequently downregulate the cardiac hypertrophy and apoptosis induced by ZAKα.     

Global phylogeny of Hadrosauridae (Dinosauria: Ornithopoda) using parsimony and Bayesian methods

The late Cretaceous hadrosaurids were the most specialized and diverse clade of ornithopod dinosaurs. Parsimony and Bayesian methods were implemented to elucidate the phylogenetic relationships of all hadrosaurid species. Traditional and geometric morphometrics were applied to discover patterns of variation containing phylogenetic information. In total, 286 phylogenetically informative characters (196 cranial and 90 postcranial) were defined and documented: the most extensive character data set ever constructed for hadrosaurid dinosaurs. Of these, 136 characters were used for the first time in phylogenetic analysis of these ornithopods, and 93 were modified from those of other authors. Parsimony and the Bayesian analysis (using the Mk model without the gamma parameter) confirmed the split of hadrosaurids into Saurolophinae and Lambeosaurinae. Saurolophines included a major clade composed of the Prosaurolophus–Saurolophus and the Kritosaurus–Gryposaurus–Secernosaurus subclades. Edmontosaurus and Shantungosaurus were recovered outside the major clade of saurolophines. The Brachylophosaurus clade was recovered as the most basal clade of saurolophines in the parsimony analysis, whereas following the Bayesian analysis it was recovered as the sister clade to the Kritosaurus–Gryposaurus–Secernosaurus clade. These two analyses resulted in a Lambeosaurinae composed of a succession of Eurasian sister taxa to two major clades: the Parasaurolophus clade and the Hypacrosaurs altispinus–Corythosaurus clade. In contrast, the Bayesian analysis using the Mk model with the gamma parameter included, resulted in an unbalanced hadrosauroid tree, with a paraphyletic Saurolophinae, and with the Prosaurolophus clade, Edmontosaurus, and Shantungosaurus as successively closer sister taxa to Lambeosaurinae. Based on the strict reduced consensus tree derived from the parsimony analysis, Hadrosauridae was redefined as the clade stemming from the most recent common ancestor of Hadrosaurus foulkii and Parasaurolophus walkeri. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159 , 435–502.     

Mutation glass-like of Drosophila melanogaster Suppresses Expression of mini-white Transgenes Depending on Their Genomic Environment

Pleiotropic recessive mutation glass-like (gl-l) found in region 8C10–8E of the X chromosome was shown to cause glass-like eyes having no boundaries between facets and a nonuniform pigment distribution determined by the endogenous white. The gl-lmutation completely inhibited expression of the mini-white transgene contained in several constructs, but the effect depended on the site of construct insertion in the genome. The mutation had no effect on the expression of the white transgene having the enhancer and flanked by insulators. The gl-l mutation did not affect the extent of mosaic eye pigmentation when a construct with mini-white was inserted in the telomeric or pericentric region. However, in most cases it completely inhibited the mosaic mini-white expression when cloned heterochromatic repeats were adjacent to the reporter gene in a construct. The gl-l gene was assumed to play a role in the formation of the chromatin structure, because the effect of its mutation on expression of the white transgene depended on the transgene insertion site, the presence of insulators or an enhancer in the vicinity of the transgene, and on the adjacent heterochromatic repeats.