A study of connective tissue macromolecules in skin of mice with goldthioglucose-induced obesity.

The effect of obesity on the connective tissue composition of skin was investigated in mice with goldthioglucose (GTG)-induced obesity. Four months after GTG treatment, the obese animals were sacrificed. Acid mucopolysaccharides, glycoproteins, collagen, and elastin were analyzed in the skin and compared to the controls. Total MPS in the skin from obese animals decreased, reflected mostly in hyaluronic acid. Chondroitin showed an increase over controls. The content of soluble glycoproteins varied; total carbohydrate and sialic acid of the glycoprotein tended to increase with obesity. Collagen and elastin both tended to decrease with obesity.     

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.     

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.     

Spatial, temporal and habitat-related variation in the abundance of large predatory fish at One Tree Reef, Australia

 Patterns of abundance of large piscivorous fish (>200 mm TL) were documented at two spatial and four temporal scales within the main lagoon of One Tree Reef on Australia’s Great Barrier Reef. Grouper (Serranidae), snapper (Lutjanidae) and wrasses (Labridae) were the most abundant large piscivores. On a large scale (hundreds of metres), patterns of predator abundance were consistently greater on the inner edge than centre of the lagoon over a range of temporal scales: days, weeks, months and years. On a small spatial scale (tens of metres), the abundance of large predatory fish was patchy. At both spatial scales, fish were consistently aggregated in particular areas and associated with specific structural features of the reef habitat. Predator abundance was high where live corals were predominant and the topography was more complex. Hence, predation pressure and its potential effects on the distribution and abundance of prey populations, both in time and space, may vary greatly within lagoonal environments. Accepted: 25 May 1997