193 research outputs found
Morphology and systematic position of Shaninopsis Isberg, 1934 (Bivalvia : Cryptodonta), from the Boda Limestone (Upper Ordovician), Sweden
No full textIn a classic study of bivalves from the Upper Ordovician (Katian) Boda Limestone, Sweden, Isberg (1934) named and described 18 species of the unusual bivalve Shaninopsis, all from the same locality. Our study of the type material indicates that only three species at most are present: Shaninopsis prona Isberg, 1934, Shaninopsis radiata Isberg, 1934, and an unnamed species. Shaninopsis features a thick, prosocline, tear-drop-shaped shell with an opisthogyrous larval shell. Anterodorsally, the shell outline appears truncated to strongly concave owing to an inset sical surface that frames a conspicuous pedal gape. Above the gape, the lunule accreted posteriorly (retrusive growth-new term) and abuts the anterior part of the ligament area, perhaps compensating for anterior splitting of the ligament during growth. The hinge plate is edentulous, with a broad, opisthodetic, monovincular ligament. Muscle scars visible include only the posterior adductor, which is set near the posteroventral shell margin. Relict calcite prismatic texture preserved on the ligament area indicates the external prismatic calcite shell layer underlaid the ligament as in cardiolid praecardioids and some inoceramiformians. Evidence for a retractable non-biomineralized sheath-like structure extending from the pedal gape is presented. Shaninopsis is reconstructed as an orthothetic, epifaunal or shallow semi-infaunal bivalve capable of deeply probing underlying sediment for H2S uptake for chemosynthesis. Shaninopsis is assigned to a new subfamily Shaninopsiinae in the family Lunulacardiidae (infraclass Cryptodonta), a group otherwise unknown in pre-upper Silurian rocks. Remarkable similarities of Shaninopsis with the Permian bivalve Eurydesma suggest a mutual though geochronologically distant phylogenetic relationship
The amoebal MAP kinase response to Legionella pneumophila is regulated by DupA
No full textThe amoeba Dictyostelium discoideum can support replication of Legionella pneumophila. Here we identify the dupA gene, encoding a putative tyrosine kinase/dual-specificity phosphatase, in a screen for D. discoideum mutants altered in allowing L. pneumophila intracellular replication. Inactivation of dupA resulted in depressed L. pneumophila growth and sustained hyperphosphorylation of the amoebal MAP kinase ERK1, consistent with loss of a phosphatase activity. Bacterial challenge of wild-type amoebae induced dupA expression and resulted in transiently increased ERK1 phosphorylation, suggesting that dupA and ERK1 are part of a response to bacteria. Indeed, over 500 of the genes misregulated in the dupA(-) mutant were regulated in response to L. pneumophila infection, including some thought to have immune-like functions. MAP kinase phosphatases are known to be highly upregulated in macrophages challenged with L. pneumophila. Thus, DupA may regulate a MAP kinase response to bacteria that is conserved from amoebae to mammals
By All Necessary Means : Brigadier General Jan-Gunnar Isberg's experiences from service in the Congo 2003-2005
No full textBy All Necessary Means [Elektronisk resurs] : Brigadier General Jan-Gunnar Isberg's experiences from service in the Congo 2003-2005
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Sandwichelement av uretancellplast : ytskiktets inverkan på förändringen av värmemotstånd med tiden /
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By All Necessary Means : Brigadier General Jan-Gunnar Isberg's experiences from service in the Congo 2003-2005
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