Allocentric representation in the human amygdala and ventral visual stream

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Genetic population structure of the monogenean parasite Gyrodactylus thymalli and its host European grayling (Thymallus thymallus) in a large Norwegian lake

Hydrobiologia - Understanding how populations are structured in space and time is a central question in evolutionary biology. Parasites and their hosts are assumed to evolve together, however,...     

Taxonomic and biological notes on a species of Iphitime (Polychaeta, Eunicida) associated with Pagurus prideaux from western Norway

On the basis of 658 specimens collected over an 11 year period, the symbiotic eunicid polychaete, Iphitime paguri Fage & Legendre, 1934, is redescribed, and its biology in its presumed preferred host, Pagurus prideaux Leach, 1815, is outlined. The main ecological part is based on sampling of Pagurus on five occasions throughout a year in Raunefjorden, southwest of Bergen. Iphitime paguri turned out to have a strong sexual dimorphism, both in outer appearance and in the morphology of the jaws. Both juveniles and mature individuals of both genders are described. The infestation rate of Pagurus prideaux was very high (as opposed to the low reported infestation rate in Pagurus bernhardus, generally regarded as the host of this species) and the symbiotic polychaetes turned out to have a distinct pattern of host utilization in different life stages. Ripe males and females were, at certain times of the year, generally found more or less intertwined in the apex of the gastropod shell inhabited by its host. Small larval stages were found in the same place. Intermediate size groups were found in the gill chamber and in a sulcus on the carapax of the pagurid host.     

Evaluation of PM3(tm) as a Geometry Generator in Theoretical Studies of Transition-Metal-Based Catalysts for Polymerizing Olefins

The PM3(tm) method has been applied to several systems of relevance to catalytic polymerization of olefins, for catalysts containing Ti, Zr or Cr. With some exceptions, PM3(tm) calculations reproduce experimental geometries of stable, closed-shell, precursors well. For stationary points along the path of monomer insertion into a metal-alkyl bond, the comparison is made to structures obtained by optimization using various first-principle methods. Large errors are uncovered for the transient structures, in particular pertaining to metal-ethylene coordination and agostic interactions. The energy profiles for four insertion reactions are computed by gradient-corrected density functional (DFTG) methods, using molecular structures taken from PM3(tm) and first-principle geometry optimizations, respectively. The chromium case is promising, giving values for the barrier to monomer insertion of 11 and 9 kcal/mol based on PM3(tm) and DFTG geometries, respectively. The Ti- and Zr-based systems are predicted to proceed downhill based on PM3(tm) structures, whereas small barriers are found when using first-principle structures. A hybrid PM3(tm)-DFTG procedure is suggested for geometry optimization, which facilitates an accurate estimate of the barrier when applied to one of the zirconium systems.     

Tissue Distribution of 14C-Diflubenzuron in Atlantic Salmon (Salmo salar)

Diflubenzuron is a potent inhibitor of chitin synthesis, with potential use against salmon lice infestations. The absorption, distribution and elimination of the substance in Atlantic salmon was examined after a single, oral dose of 75 mg/kg body weight. The kinetic properties were studied by whole-body autoradiography, liquid scintillation counting and thin layer chromatography, using a 14C-labelled isotope of the substance. The drug was poorly absorbed from the intestine, but reached a concentration of more than 4 µg/g in the mucus layer of the skin 2 days after administration. If maintained for several days, this concentration is probably sufficient to control all moulting stages of sea lice in Atlantic salmon. The main route of excretion was via the bile.