Effect of caffeine on the rho--induction with ethidium bromide in Saccharomyces cerevisiae

Summary It is shown that caffeine antagonizes petiteinduction with ethidium bromide under non-growth conditions when administered during or after mutagenic treatment.Caffeine itself is shown to be a petite-inducing agent when cells are grown in liquid glucose-completemedium in the presence of the drug.A possible mode of action of caffeine in the ethidium bromide induced petite-mutagenesis is discussed.     

An unusual receptor in the octopus

The epithelium of the rim of the octopus sucker is the site of several different types of primary receptors. One is a non-ciliated cell with unusual characteristics. (1) The surface of the cell is extremely irregular with finger-like extensions of cytoplasm, especially far reaching in the basal region. (2) The slender neck contains a canal whose apical opening is in contact with the environment. This canal is lined with microvilli and contains granular material in an electron-dense matrix. (3) Patches of presumed glycogen granules occur throughout the cell, being especially abundant in the outer reaches of the cytoplasmic extensions. Their presence, together with numerous mitochondria and free ribosomes, indicate a high intrinsic metabolism. (4) Small fascicles of microtubules are randomly situated throughout the perikaryon. They gather into a coherent system of larger and larger bundles which ultimately enter the axon leading from the cell. This axon extends some distance in the basal region of the epithelium before crossing the subepithelial space to enter the infundibular muscle. Possible functions of this cell are discussed. On the basis of its specific position on the sucker and its intrinsic morphology we suggest that it is a mechanoreceptor involved in shape and/or negative pressure discrimination.     

Aggregation of truncated GST-HD exon 1 fusion proteins containing normal range and expanded glutamine repeats.

We have shown previously by electron microscopy that the purified glutathione S-transferase (GST)-Huntington's disease (HD) exon 1 fusion protein with 51 glutamine residues (GST-HD51) is an oligomer, and that site-specific proteolytic cleavage of this fusion protein results in the formation of insoluble more highly ordered protein aggregates with a fibrillar or ribbon-like morphology (E. Scherzinger et al. (1997) Cell 90, 549-558). Here we report that a truncated GST HD exon 1 fusion protein with 51 glutamine residues, which lacks the proline-rich region C-terminal to the polyglutamine (polyQ) tract (GST-HD51 delta P) self-aggregates into high-molecular-mass protein aggregates without prior proteolytic cleavage. Electron micrographs of these protein aggregates revealed thread-like fibrils with a uniform diameter of ca. 25 nm. In contrast, proteolytic cleavage of GST-HD51 delta P resulted in the formation of numerous clusters of high-molecular-mass fibrils with a different, ribbon-like morphology. These structures were reminiscent of prion rods and beta-amyloid fibrils in Alzheimer's disease. In agreement with our previous results with full-length GST-HD exon 1, the truncated fusion proteins GST-HD20 delta P and GST-HD30 delta P did not show any tendency to form more highly ordered structures, either with or without protease treatment.     

Utilization of mangrove wood products around mida creek (Kenya) amongst subsistence and commercial users

Mida Creek (Kenya) comprises mangrove forests and other marine resources that are of economic, ecological, and environmental importance to the local village communities. In total 116 households (100 of which could be used for numerical analysis), which are estimated to correspond to a coverage of ca. 30% of the total Mida Creek population, were interviewed to assess the human reliance on mangrove resources in Mida Creek. The survey indicates that mangroves are a major resource of wood for house construction, fuel wood, charcoal, and boat building. Minor uses of mangrove products include pharmaceutical and medicinal applications, tanning material, and furniture making. Rhizophora mucronata, Ceriops tagal, and Bruguiera gymnorrhiza are the major resources for house construction and fuel wood, while Sonneratia alba and Xylocarpus granatum were reported to be useful for boat building and medicinal uses respectively. The survey further describes harvesting activities and house construction, and reveals species preferences within this one particular use. As a result of depletion of the supply and the banning of mangrove harvesting, the local people are turning to other wood materials and to poaching. In our view, local utilization patterns rather than global usefulness data are required to establish a conservation policy of both mangroves and users’ subsistence requirements.     

Cytokine regulation of facilitated glucose transport in human articular chondrocytes.

Glucose serves as the major energy substrate and the main precursor for the synthesis of glycosaminoglycans in chondrocytes. Facilitated glucose transport represents the first rate-limiting step in glucose metabolism. This study examines molecular regulation of facilitated glucose transport in normal human articular chondrocytes by proinflammatory cytokines. IL-1beta and TNF-alpha, and to a lesser degree IL-6, accelerate facilitated glucose transport as measured by [(3)H]2-deoxyglucose uptake. IL-1beta induces an increased expression of glucose transporter (GLUT) 1 mRNA and protein, and GLUT9 mRNA. GLUT3 and GLUT8 mRNA are constitutively expressed in chondrocytes and are not regulated by IL-1beta. GLUT2 and GLUT4 mRNA are not detected in chondrocytes. IL-1beta stimulates GLUT1 protein glycosylation and plasma membrane incorporation. IL-1beta regulation of glucose transport in chondrocytes depends on protein kinase C and p38 signal transduction pathways, and does not require phosphoinositide 3-kinase, extracellular signal-related kinase, or c-Jun N-terminal kinase activation. IL-1beta-accelerated glucose transport in chondrocytes is not mediated by endogenous NO or eicosanoids. These results demonstrate that stimulation of glucose transport represents a component of the chondrocyte response to IL-1beta. Two classes of GLUTs are identified in chondrocytes, constitutively expressed GLUT3 and GLUT8, and the inducible GLUT1 and GLUT9.