Transdifferentiation of larval Xenopus laevis iris under the influence of the pituitary

Fragments of larval Xenopus laevis dorsal iris implanted together with the pituitary into the tail fin transdifferentiate into neural retina. On the contrary, in the control experiments the implanted tissues, dorsal iris alone, pituitary, or dorsal iris with liver fragments, do not undergo any retinal transformation.     

Loss of virulence of canine distemper virus is associated with a structural change recognized by a monoclonal antibody.

The monoclonal antibody (mAB) L1, which binds to the nucleocapsid protein of canine distemper virus (CDV), was shown to bind to avirulent CDV obtained after serial passages in Vero cells, but not to two different virulent demyelinating CDV-strains propagated in dog glial cell cultures. However, when both virulent CDV-strains were passaged through Vero cells they expressed, after a number of passages, an epitope recognized by mAB L1. The occurrence of the L1 epitope appeared to coincide with loss of virulence in animal inoculation experiments.     

Genotoxic effects of dithane M-45 on the bone marrow cells of mice in vivo

Genotoxic effects of dithane M-45 were studied on the bone marrow cells of male albino mice (Lacca strain) in vivo. Different doses (30 mg, 40 mg and 300 mg/kg b.wt) of dithane M-45 were injected intraperitoneally and their effects were investigated after time intervals of 1, 2, 5 and 10 days. The chromosomal aberrations observed in the bone marrow cells of male mice after treatment with dithane M-45 were fragments, rings, dicentric chromosomes, terminal chromatid deletions, chromatid gaps and breaks. In addition to these chromosomal aberrations, physiological effects such as uneven stretching of chromatin material, end-to-end chromosomal associations, exchange configurations, clumping, stickiness and centromeric associations were also observed.     

The influence of chronic nicotine treatment on stress-induced gastric ulceration and emptying rate in rats.

Ten-day treatment with nicotine (5, 25 or 50 micrograms/ml drinking water) dose-dependently intensified gastric ulceration induced by cold-restraint, and emptying rate. Stomach contractions produced by graded doses of bethanechol i.v. were elevated further by nicotine treatment. It is suggested that chronic nicotine administration produces hypersensitivity of the gastric muscarinic receptors; stomach hypermotility contributes to the ulcer-worsening action of the alkaloid.     

Chromosome 17-linked dementias

Chromosome 17-linked dementias have been defined by linkage analysis. The most common of these syndromes has been estimated to be the cause of between 2 and 20% of all dementia and has alternately been called frontotemporal dementia, Pick's disease (without Pick bodies) and dementia lacking distinctive features [1 – 3]. The identification of the mutation responsible for these conditions in a group of clinically and pathologically heterogeneous disorders may allow us to gain broad insight into the processes of neurodegeneration.     

Triplet repeat disorders: discussion of molecular mechanisms

Comparison of the growing number of disorders known to be associated with triplet repeat expansions reveals both common features and a diversity of molecular pathways. Despite significant progress towards the characterization of proteins coded by the mutant genes, the complex nature of these disorders requires identification of all molecular components of the triplet repeat pathways. In this brief review we will discuss recent progress in determining the molecular mechanisms of disorders with unstable trinucleotide mutations. Received 13 January 1999; received after revision 8 March 1999; accepted 9 March 1999     

Transient and constitutive repression of cytoplasmic translation signaling in cells with mtDNA mutation

Cytoplasmic translation is under sophisticated control but how cells adapt its rate to constitutive loss of mitochondrial oxidative phosphorylation is unknown. Here we show that translation is repressed in cells with the pathogenic A3243G mtDNA mutation or in mtDNA-less ρ⁰ cells by at least two distinct pathways, one transiently targeting elongation factor eEF-2 and the other initiation factor eIF-2α constitutively. Under conditions of exponential cell growth and mammalian target of rapamycin (mTOR) activation, eEF-2 becomes transiently phosphorylated by an AMP-activated protein kinase (AMPK)-dependent pathway, especially high in mutant cells. Independent of AMPK and mTOR, eIF-2α is constitutively phosphorylated in mutant cells, likely a signature of endoplasmic reticulum (ER)-stress response induced by the loss of oxidative phosphorylation. While the AMPK/eEF-2K/eEF-2 pathway appears to function in adaptation to physiological fluctuations in ATP levels in the mutant cells, the ER stress signified by constitutive protein synthesis inhibition through eIF-2α-mediated repression of translation initiation may have pathobiochemical consequences. Received 29 October 2008; received after revision 11 December 2008; accepted 16 December 2008     

Overactive bone morphogenetic protein signaling in heterotopic ossification and Duchenne muscular dystrophy

Bone morphogenetic proteins (BMPs) are important extracellular cytokines that play critical roles in embryogenesis and tissue homeostasis. BMPs signal via transmembrane type I and type II serine/threonine kinase receptors and intracellular Smad effector proteins. BMP signaling is precisely regulated and perturbation of BMP signaling is connected to multiple diseases, including musculoskeletal diseases. In this review, we will summarize the recent progress in elucidation of BMP signal transduction, how overactive BMP signaling is involved in the pathogenesis of heterotopic ossification and Duchenne muscular dystrophy, and discuss possible therapeutic strategies for treatment of these diseases.     

Dehydrogenation of khusilic acid

Zusammenfassung Neue Befunde zur Interpretation der Selendehydrierung.