Supernumerary teeth in the European lynx, Lynx lynx lynx, and their evolutionary significance

Supernumerary upper second deciduous premolars and lower second molars are reported in lynx, Lynx lynx lynx (L.), from Norway at frequencies comparable with the situation reported from lynx populations in other countries. Other authors have interpreted these anomalies as true atavisms in response to altered environmental conditions, and consequently as being contradictory with Dollo's law. The author suggests an alternative interpretation of the appearance of supernumerary teeth, which brings such phenomena in line with Dollo's law and the recent modern synthesis of evolution.     

Effects of site,depth and sori origin on the growth and minerals composition of cultivated Saccharina latissima (Phaeophyceae) in the north of Norway

Journal of Applied Phycology - Interest in the cultivation of Saccharina latissima is increasing in the north of Norway. In the present study, S. latissima was cultivated at two sites (Kraknes and...     

Why the free floating macrophyte Stratiotes aloides mainly grows in highly CO2-supersaturated waters

We examined how the freely floating macrophyte, Stratiotes aloides L., sampled from a CO₂-supersaturated pond, changes leaf morphology, photosynthesis and inorganic carbon acquisition during its different submerged and emerged life stages in order to evaluate whether S. aloides requires consistently supersaturated CO₂ conditions to grow and complete its life cycle. Submerged rosettes formed from over-wintering turions had typical traits of submerged plants with high specific leaf area and low chlorophyll a concentrations. Emergent leaf parts of mature, floating specimens had typical terrestrial traits with stomata, low specific leaf area and high chlorophyll a content, while offsets formed vegetatively and basal, submerged parts of mature plants showed traits in between. All submerged leaf types exhibited some ability to use HCO₃⁻ but only rosettes formed from turions had efficient HCO₃⁻ use. Rosettes also had the highest CO₂ affinity and maximum CO₂-saturated photosynthesis in water. Half-saturation constants for CO₂ (21–74 μM CO₂) were for all submerged leaf parts 5–140 times lower than the concentrations of free CO₂ in the pond (350–2800 μM CO₂). Emergent leaves were less efficient in water but had significantly higher photosynthesis than submerged, mature leaf parts in air, and rates of photosynthesis of emergent leaves in air were three to five times higher than rates of CO₂-saturated photosynthesis of the three submerged leaf types in water. Underwater photosynthetic rates estimated at CO₂ concentrations corresponding to air equilibrium were not sufficiently high to support any noticeable growth except for rosettes, in which bicarbonate utilization combined with high CO₂ affinity resulted in photosynthetic rates corresponding to almost 34% of maximum rates at high free CO₂. We conclude that S. aloides requires consistently high CO₂-supersaturation to support high growth and to complete its life cycle, and we infer that this requirement explains why S. aloides mainly grows in ponds, ditches and reed zones that are characterized by strong CO₂-supersaturation.     

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.