The anabolic action of intermittent parathyroid hormone on cortical bone depends partly on its ability to induce nitric oxide‐mediated vasorelaxation in BALB/c mice

There is strong evidence that vasodilatory nitric oxide (NO) donors have anabolic effects on bone in humans. Parathyroid hormone (PTH), the only osteoanabolic drug currently approved, is also a vasodilator. We investigated whether the NO synthase inhibitor L‐NAME might alter the effect of PTH on bone by blocking its vasodilatory effect. BALB/c mice received 28 daily injections of PTH[1–34] (80 µg/kg/day) or L‐NAME (30 mg/kg/day), alone or in combination. Hindlimb blood perfusion was measured by laser Doppler imaging. Bone architecture, turnover and mechanical properties in the femur were analysed respectively by micro‐CT, histomorphometry and three‐point bending. PTH increased hindlimb blood flow by >30% within 10 min of injection (P < 0.001). Co‐treatment with L‐NAME blocked the action of PTH on blood flow, whereas L‐NAME alone had no effect. PTH treatment increased femoral cortical bone volume and formation rate by 20% and 110%, respectively (P < 0.001). PTH had no effect on trabecular bone volume in the femoral metaphysis although trabecular thickness and number were increased and decreased by 25%, respectively. Co‐treatment with L‐NAME restricted the PTH‐stimulated increase in cortical bone formation but had no clear‐cut effects in trabecular bone. Co‐treatment with L‐NAME did not affect the mechanical strength in femurs induced by iPTH. These results suggest that NO‐mediated vasorelaxation plays partly a role in the anabolic action of PTH on cortical bone. © 2016 The Authors. Cell Biochemistry and Function published by John Wiley & Sons, Ltd.     

Differential regulation of metabotropic glutamate receptor 5-mediated phosphoinositide hydrolysis and extracellular signal-regulated kinase responses by protein kinase C in cultured astrocytes

The metabotropic glutamate receptor 5 (mGluR5) exhibits a rapid loss of receptor responsiveness to prolonged or repeated agonist exposure. This receptor desensitization has been seen in a variety of native and recombinant systems, and is thought to result from receptor-mediated, protein kinase C (PKC)-dependent phosphorylation of the receptor, uncoupling it from the G protein in a negative feedback regulation. We have investigated the rapid PKC-mediated desensitization of mGluR5 in cortical cultured astrocytes by measuring downstream signals from activation of mGluR5. These include activation of phosphoinositide (PI) hydrolysis, intracellular calcium transients, and extracellular signal-regulated kinase 2 (ERK2) phosphorylation. We present evidence that PKC plays an important role in rapid desensitization of PI hydrolysis and calcium signaling, but not in ERK2 phosphorylation. This differential regulation of mGluR5-mediated responses suggests divergent signaling and regulatory pathways which may be important mechanisms for dynamic integration of signal cascades.     

Cross-fertilization and structural comparison of egg extracellular matrix glycoproteins from Xenopus laevis and Xenopus tropicalis

While the anuran amphibian Xenopus laevis is a widely used vertebrate model system, it is not optimal for genetic manipulations due to its tetraploid genome and long generation time. A current alternative amphibian model system, Xenopus tropicalis, has the advantages of a diploid genome and a much shorter generation time. We undertook a comparative investigation of X. tropicalis egg extracellular matrix glycoproteins in relation to those already characterized in X. laevis. Fertilization methods and isolation of egg extracellular molecules were directly transferable from X. laevis to X. tropicalis. Cross-fertilizations were successful in both directions, indicating similar molecules involved in sperm-egg interactions. Egg envelopes analyzed by SDS-PAGE were found to have almost identical gel patterns, whereas jelly component profiles were similar only for the larger macromolecules (>90 kDa). The cDNA sequences for egg envelope glycoproteins ZPA, ZPB, ZPC, ZPD and ZPAX, and also egg cortical granule lectin involved in the block to polyspermy, were cloned for X. tropicalis and showed a consistent approximately 85% amino acid identity to the X. laevis sequences. Thus, homologous egg extracellular matrix molecules perform the same functions, and the molecular and cellular mechanisms of fertilization in these two species are probably equivalent.     

Nuclear gene trees and the phylogenetic relationships of the mangabeys (Primates: Papionini)

Phylogenetic relationships of mangabeys within the Old World monkey tribe Papionini are inferred from analyses of nuclear DNA sequences from five unlinked loci. The following conclusions are strongly supported, based on congruence among trees derived for the five separate gene regions: (1) mangabeys are polyphyletic within the Papionini; (2) Cercocebus is the sister taxon to the genus Mandrillus; and (3) Lophocebus belongs to a clade with Papio and Theropithecus, with Papio as its most likely sister taxon. Morphologically based phylogenies positing mangabey monophyly were evaluated by mapping the sequences for each locus on these trees. The data seem to fit these trees poorly in both maximum-parsimony and likelihood analyses. Incongruence among nuclear gene trees occurred in the interrelationships among Lophocebus, Papio, and Theropithecus. Several factors that may account for this incongruence are discussed, including sampling error, random lineage sorting, and introgression.      

PPCMatrix: a PowerPC dotmatrix program to compare large genomic sequences against protein sequences

Summary : An interactive dotmatrix program for the MacOS was designed that allows comparison of DNA to protein sequences using nested 3-frame translations. Availability : Shareware, available at http://copan.bioz.unibas.ch/software/ Contact : burglin@ubaclu. unibas.ch      

Cell-mediated immune responses in vitro. III. Elimination of specific cytotoxic lymphocyte responses by 3H-thymidine suicide.

The role of cellular proliferation in the development of cytotoxic lymphocyte (CL) responses in one-way mixed lymphocyte reactions was investigated by using tritiated thymidine of high specific activity to kill proliferating cells. To develop maximum CL responses, responding lymphoid cells must proliferate for approximately 72 hr; thereafter, precursors of CL appear to differentiate into active CL without further proliferation. Different alloantigen-sensitive precursor cell populations participate in the CL responses to each of two sets of stimulating alloantigens. When cells responding to one set of alloantigens were selectively destroyed after incorporating the hot thymidine, the surviving cells retained the capacity to develop a normal CL response to the second set of alloantigens.