The Mechanism of Enzyme Actions: DR. K. GEORGE FALK .................................. 471 Obituary: Michael Idvorsky Pupin: PROFESSOR A. P. WILLS 475 Scientific Events: Annual Meeting of the Trustees of Science Service; Annual Meeting of the American Academy of Arts and Sciences; Betirement of the Secretary of the Zoological Society of London; Award of the Daniel Guggenheim Medal for Aeronauti...

Endosymbiotic associations between bacteria and eukaryotes are commonly reported (Taylor, 1983). The prokaryotic cell (the cytobiont (Taylor, 1979) or endocytobiont (Schwemmler, 1979)) may live non-specifically within the intracellular habitat provided by the host, but some endosymbiotic bacteria are specialized to invade specific cellular organelles. Three species of the bacterial genus Holosp...

A method is described for the simultaneous treatment of 42 (or more) stocks of Paramecium, and their adaptation to growth in axenic culture. Samples of dense cultures of these ciliates growing with Enterobacter aerogenes are rendered bacteria-free by migration through 2 sets of tubes containing Adaptation Medium (Peters' salts solution, stigmaterol, vitamins, and autoclaved E. aerogenes). The 2...

Nano titanium dioxide (nTiO2) is the most abundantly released engineered nanomaterial (ENM) in aquatic environments. Therefore, it is prudent to assess its fate and its effects on lower trophic-level organisms in the aquatic food chain. A predator-and-prey-based laboratory microcosm was established using Paramecium caudatum and Escherichia coli to evaluate the effects of nTiO2. The surface inte...

In this study, we revealed that the lectin wheat germ agglutinin (WGA) and its specific binding sugars, N-acetylneuraminic acid (NeuAc) and Nacetylglucosamine (GlcNAc), inhibited mating pair formation in Paramecium caudatum. The concentrations that caused 50% inhibition (IC50) were 17 nM, 3 mM and 30 mM, respectively. Using FITCWGA, it was shown fluorescence-cytochemically that WGA bound to the...

The nanotechnology revolution has allowed us to speculate on the possibility of hybridising nanoscale materials with live substrates, yet significant doubt still remains pertaining to the effects of nanomaterials on biological matter. In this investigation, we cultivate the ciliated protistic pond-dwelling microorganism Paramecium caudatum in the presence of excessive quantities of magnetite na...

1. The rate of pulsation of the anterior contractile vacuole of Paramecium caudatum under chloretone anesthesia has been determined over a range of temperatures from 9-31 degrees C. It has been found that the rate is a logarithmic function of the temperature according to the Arrhenius equation. From 9-16 degrees the temperature characteristic (micro) has the value 25,600; from 16-22 degrees it ...

The anticalmodulin drug, W-7 [N-(6 aminohexyl)-5-chloro-1-naphthalenesulphonamide] specifically inhibits the voltage-dependent Ca-current of Paramecium as well as the behavioural consequence of Ca2+ influx, backward swimming. The dechlorinated analogue, W-5, is four to five times less effective. Analysis of membrane currents under voltage clamp shows that W-7 not only reversibly inhibits the vo...

When cells of the behavioral mutant cnrC of Paramecium caudatum were mated with the wild type, phenotype change from CNR (no backward swinning) to wild type in the cnrC mate occurred immediately after the formation of tight pairs. No change of phenotype occurred when cells of cnrA or cnrB were mated with wild type. Phenotypic change from CNR to wild type in cells of cnrC was also induced by mic...