1α,25-dihydroxyvitamin D3 hybrid analogs with structural changes at both the A-ring and the C,D-ring side-chain

Calcitrol analogs 5, designed to combine two remote structural changes each of which separately produces a sharply different biological profile, have biological activities that are a blending of the effects of each structural change.     

A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths

Molecular systematists need increased access to nuclear genes. Highly conserved, low copy number protein-encoding nuclear genes have attractive features for phylogenetic inference but have heretofore been applied mostly to very ancient divergences. By virtue of their synonymous substitutions, such genes should contain a wealth of information about lower-level taxonomic relationships as well, with the advantage that amino acid conservatism makes both alignment and primer definition straightforward. We tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene in the noctuid moth subfamily Heliothinae, which has probably diversified since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing heliothine groupings strongly supported by previous morphological and allozyme studies. The single most parsimonious gene tree and the neighbor-joining tree for all nucleotides show almost complete concordance with the morphological tree. Homoplasy and pairwise divergence levels are low, transition/transversion ratios are high, and phylogenetic information is spread evenly across gene regions. The EF-1 alpha gene and presumably other highly conserved genes hold much promise for phylogenetics of Tertiary age eukaryote groups.      

Chick embryo fibroblasts produce two forms of hyaluronidase

Cultured chick embryo fibroblasts derived from skin and skeletal muscle exhibit hyaluronidase activity both associated with the cell layer and secreted into the medium. Although both forms of the enzyme have a number of similar characteristics (R.W. Orkin and B.P. Toole, 1980, J. Biol. CHem. 255), they differ in thermal stability at neutral pH and in behavior on ion-exchange chromatography. Both forms of the enzyme are equally stable at acidic pH for long intervals, but the cell-associated hyaluronidase is significantly less stable than the secreted froms at neutral pH and at temperatures more than or equal to 30 degrees C. Neither the presence of proteases nor inhibitors of hyaluronidase appear to be involved in the cell-asspcoated enzyme. Chromatography of the two forms of hyaluronidase on carboxymethyl cellulose reveals that most (60-90 percent) of the secreted form of the enzyme elutes at a lower ionic strength than the cell- associated enzyme. Treatment of the secreted form of hyaluronidase with neuraminidase shifts its elution profile on carboxymethyl cellulose toward that of the cell-associated form, and also decreases its thermal stability at neutral pH. In contrast, treatment of the secreted form of hyaluronidase with alkaline phosphatase has no detectable effect. These data suggest that the secreted hyaluronidase differs from the cellular form in possessing additional sialic acid residues which endow the former with increased stability in the extracellular milieu.     

Mitochondrial division ensures the survival of postmitotic neurons by suppressing oxidative damage

Mitochondria divide and fuse continuously, and the balance between these two processes regulates mitochondrial shape. Alterations in mitochondrial dynamics are associated with neurodegenerative diseases. Here we investigate the physiological and cellular functions of mitochondrial division in postmitotic neurons using in vivo and in vitro gene knockout for the mitochondrial division protein Drp1. When mouse Drp1 was deleted in postmitotic Purkinje cells in the cerebellum, mitochondrial tubules elongated due to excess fusion, became large spheres due to oxidative damage, accumulated ubiquitin and mitophagy markers, and lost respiratory function, leading to neurodegeneration. Ubiquitination of mitochondria was independent of the E3 ubiquitin ligase parkin in Purkinje cells lacking Drp1. Treatment with antioxidants rescued mitochondrial swelling and cell death in Drp1KO Purkinje cells. Moreover, hydrogen peroxide converted elongated tubules into large spheres in Drp1KO fibroblasts. Our findings suggest that mitochondrial division serves as a quality control mechanism to suppress oxidative damage and thus promote neuronal survival.     

The structure of isolated cardiac Myosin thick filaments from cardiac Myosin binding protein-C knockout mice

Mutations in the thick filament associated protein cardiac myosin binding protein-C (cMyBP-C) are a major cause of familial hypertrophic cardiomyopathy. Although cMyBP-C is thought to play both a structural and a regulatory role in the contraction of cardiac muscle, detailed information about the role of this protein in stability of the thick filament and maintenance of the ordered helical arrangement of the myosin cross-bridges is limited. To address these questions, the structure of myosin thick filaments isolated from the hearts of wild-type mice containing cMyBP-C (cMyBP-C^+/+) were compared to those of cMyBP-C knockout mice lacking this protein (cMyBp-C^−/−). The filaments from the knockout mice hearts lacking cMyBP-C are stable and similar in length and appearance to filaments from the wild-type mice hearts containing cMyBP-C. Both wild-type and many of the cMyBP-C^−/− filaments display a distinct 43 nm periodicity. Fourier transforms of electron microscope images typically show helical layer lines to the sixth layer line, confirming the well-ordered arrangement of the cross-bridges in both sets of filaments. However, the “forbidden” meridional reflections, thought to derive from a perturbation from helical symmetry in the wild-type filament, are weaker or absent in the transforms of the cMyBP-C^−/− myocardial thick filaments. In addition, the cross-bridge array in the absence of cMyBP-C appears more easily disordered.