Cellular and secreted tumor plasminogen activator: The effects of NaCl

Summary Plasminogen activator, secreted by metastatic tumor cells, was strongly inhibited in buffer or tissue culture medium containing physiological concentrations of NaCl. Intact cells, however, expressed strong activity under similar conditions. Thus, if plasminogen activator is involved in invasion and metastasis, the cellular activity, acting as an ectoenzyme, may be more important than secreted enzyme under physiological conditions.     

Water alteration of rocks and soils on Mars at the Spirit rover site in Gusev crater

Gusev crater was selected as the landing site for the Spirit rover because of the possibility that it once held a lake. Thus one of the rover's tasks was to search for evidence of lake sediments. However, the plains at the landing site were found to be covered by a regolith composed of olivine-rich basaltic rock and windblown 'global' dust. The analyses of three rock interiors exposed by the rock abrasion tool showed that they are similar to one another, consistent with having originated from a common lava flow. Here we report the investigation of soils, rock coatings and rock interiors by the Spirit rover from sol (martian day) 1 to sol 156, from its landing site to the base of the Columbia hills. The physical and chemical characteristics of the materials analysed provide evidence for limited but unequivocal interaction between water and the volcanic rocks of the Gusev plains. This evidence includes the softness of rock interiors that contain anomalously high concentrations of sulphur, chlorine and bromine relative to terrestrial basalts and martian meteorites; sulphur, chlorine and ferric iron enrichments in multilayer coatings on the light-toned rock Mazatzal; high bromine concentration in filled vugs and veins within the plains basalts; positive correlations between magnesium, sulphur and other salt components in trench soils; and decoupling of sulphur, chlorine and bromine concentrations in trench soils compared to Gusev surface soils, indicating chemical mobility and separation.     

CD1c-mediated T-cell recognition of isoprenoid glycolipids in Mycobacterium tuberculosis infection

The discovery of the CD1 antigen presentation pathway has expanded the spectrum of T-cell antigens to include lipids, but the range of natural lipid antigens and functions of CD1-restricted T cells in vivo remain poorly understood. Here we show that the T-cell antigen receptor and the CD1c protein mediate recognition of an evolutionarily conserved family of isoprenoid glycolipids whose members include essential components of protein glycosylation and cell-wall synthesis pathways. A CD1c-restricted, mycobacteria-specific T-cell line recognized two previously unknown mycobacterial hexosyl-1-phosphoisoprenoids and structurally related mannosyl-beta1-phosphodolichols. Responses to mannosyl-beta1-phosphodolichols were common among CD1c-restricted T-cell lines and peripheral blood T lymphocytes of human subjects recently infected with M. tuberculosis, but were not seen in naive control subjects. These results define a new class of broadly distributed lipid antigens presented by the CD1 system during infection in vivo and suggest an immune mechanism for recognition of senescent or transformed cells that are known to have altered dolichol lipids.     

A haemagglutinin in the tissue fluid of the Pacific oyster,Crassostrea gigas,with specificity for sialic acid residues in glycoproteins

Summary An agglutinin for human red cells has a specificity for sialic acid and a high affinity for bovine salivary glycoprotein. Digestion of the glycoprotein with Pronase or neuraminidase indicated that binding of sialic acid to receptors in the agglutinin is the first tepp in the mechanism of formation of a stable complex between ligand and receptor.We wish to thank Dr. P. Walne, Conwy Laboratory, MAFF, for generous supplies of Crassostrea gigas. One of us (SWH) wishes to thank the Natural Environment Research Council for financial support.     

Improved impregnation of degenerating boutons in Nauta-Laidlaw preparations

Zusammenfassung InNauta-Laidlaw-Präparaten werden die degenerierenden Endfüsschen im Nucleus cervicalis lateralis sowie im Cerebellum der Katze viel vollständiger dargestellt, als nach andern Imprägnations-techniken; Voraussetzung dazu ist jedoch, dass die Perfusion gemässKoenig, Groat undWindle durch diejenige vonHolt undHicks ersetzt wurde.