An origin of the radio jet in M87 at the location of the central black hole

Powerful radio jets from active galactic nuclei are thought to be powered by the accretion of material onto the supermassive black hole (the 'central engine'). M87 is one of the closest examples of this phenomenon, and the structure of its jet has been probed on a scale of about 100 Schwarzschild radii (R(s), the radius of the event horizon). However, the location of the central black hole relative to the jet base (a bright compact radio 'core') remains elusive. Observations of other jets indicate that the central engines are located about 10(4)-10(6)R(s) upstream from the radio core. Here we report radio observations of M87 at six frequencies that allow us to achieve a positional accuracy of about 20?microarcseconds. As the jet base becomes more transparent at higher frequencies, the multifrequency position measurements of the radio core enable us to determine the upstream end of the jet. The data reveal that the central engine of M87 is located within 14-23R(s) of the radio core at 43?GHz. This implies that the site of material infall onto the black hole and the eventual origin of the jet reside in the bright compact region seen on the image at 43?GHz.     

Elucidation of the relationship between enzyme activity and internal motion using a lysozyme stabilized by cavity-filling mutations

We investigated the activity and the internal motions of a stabilized mutant hen lysozyme (HEL) in which the residues M12 and L56 were mutated to L and F, respectively (LF mutant HEL). The result of the activity measurements against glycol chitin at various temperatures suggested that the temperature dependence of the activity of LF mutant HEL shifted to the high-temperature side compared with that of wild-type HEL. The detailed internal motions of LF mutant HEL in the absence and presence of a substrate analogue, (NAG)₃, were examined by model-free analysis at 35°C. The results showed that the internal motions of LF mutant HEL in the presence of (NAG)₃ were drastically restricted compared with those in wild-type HEL. Our findings thus suggested that the mutation to the stabilized lysozyme restricted internal motions required for the enzymatic reaction.Received 8 February 2005; accepted 10 March 2005Y. Yoshida and T. Ohkuri contributed equally to this work.     

Effects of Avermectin Bla on the motility of various parasitic helminths

Summary Using an isotonic transducer recently devised in Japan, it was observed that Avermectin Bla, a new anthelmintic, caused paralyzing effects onAngiostrongylus cantonensis andMetastrongylus elongatus at concentrations of more than 3.6×10^–18 M.     

Studies on chemotherapy of parasitic helminths (IX). Effects of praziquantel on the motility of various parasitic helminths and isolated host tissues

Summary Praziquantel (PQ) caused spastic and/or paralytic actions on the motility of various parasitic helminths and isolated host tissue preparations, through a neuropharmacological mechanism.     

Studies on chemotherapy of parasitic helminths (V). Effects of niclosamide on the motility of various parasitic helminths

Summary Niclosamide, a well-known antitapeworm drug, caused spastic and/or paralytic actions on the motility of various preparations including parasitic cestodes, trematodes, nematodes, and host isolated tissues.