Biliary secretion,retention and excretion of five 14C-labelled polychlorinated biphenyls in the rat

Five ¹⁴C-labelled polychlorinated biphenyls: 2,4′,5-trichlorobiphenyl, 2,2′,4,5′-tetrachlorobiphenyl, 2,2′,4,5,5′-pentachlorobiphenyl, 2,2′,3,4,4′-pentachlorobiphenyl and 2,2′,4,4′,5,5′-hexachlorobiphenyl were administered orally to bile-cannulated rats. The activity secreted in the bile, excreted in the feces and the urine was determined. Residues of radioactivity in certain tissues and the carcass were also measured.The trichlorobiphenyl showed the highest absorption (93.8%±5.4) from the gastrointestinal tract and biliary secretion of radioactivity (87.6%±6.1 of the dose). The hexachlorobiphenyl showed the lowest absorption and biliary secretion, 28.2%±1.4 and 18.6%±1.3, respectively. The urinary excretion was low and the radioactive residues in the eviscerated carcasses increased with the chlorine content of the biphenyls.     

Keeping the blood flowing—plasminogen activator genes and feeding behavior in vampire bats

The blood feeding vampire bats emerged from New World leaf-nosed bats that fed on fruit and insects. Plasminogen activator, a serine protease that regulates blood coagulation, is known to be expressed in the saliva of Desmodus rotundus (common vampire bat) and is thought to be a key enzyme for the emergence of blood feeding in vampire bats. To better understand the evolution of this biological function, we studied the plasminogen activator (PA) genes from all vampire bat species in light of their feeding transition to bird and subsequently mammalian blood. We include the rare species Diphylla ecaudata and Diaemus youngi, where plasminogen activator had not previously been studied and demonstrate that PA gene duplication observed in Desmodus is not essential to the vampire phenotype, but relates to the emergence of predominant mammalian blood feeding in this species. Plasminogen activator has evolved through gene duplication, domain loss, and sequence evolution leading to change in fibrin-specificity and susceptibility to plasminogen activator inhibitor-1. Before undertaking this study, only the four plasminogen activator isoforms from Desmodus were known. The evolution of vampire bat plasminogen activators can now be linked phylogenetically to the transition in feeding behavior among vampire bat species from bird to mammalian blood. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Geochemistry and acidity of sulphide-bearing postglacial sediments of western Finland

The geochemistry, mineralogy, acidity and electric conductivity of sulphide-bearing postglacial sediments located on the coastal plains of western Finland were studied. Grain size and mineralogical analysis (eight samples studied) indicated that the sediments are silts dominated by primary minerals (quartz, feldspars), and that the clay fraction (<2µm), which made up less than one-third of the bulk samples, is enriched in phyllosilicates but depleted in quartz and feldspars, relative to bulk samples. As compared to the metal contents of the fine-fraction of glacial till (data of the Geological Survey of Finland), the fine sediments appear to be enriched in sulphur (median = 0.54%) and trace metals such as Ni (31 µg g^–1), Zn (90 µg g^–1), Co (13 µg g^–1), Cr (48 µg g^–1) and V (50 µg g^–1). Statistical analysis indicated that aluminosilicates are the principal carrier phases of trace metals, and that sulphides and organic matter only partially control the distribution of elements other than S and C. A 3-g portion of 232 samples was oxidised in the laboratory by atmospheric oxygen for a period of 1 year. After this period of oxidation, 15 ml of water was added, after which pH and electric conductivity of the suspensions (sediment:water, 1:5) were measured. The quantities of elements mobilised by the oxidation was calculated from the dissolved concentrations found in 3 g of oxidised sediment suspended in 30 ml of deionised water (eight samples studied). The results of the experiment showed that the impact of sulphide oxidation on the pH and conductivity of the sediments is large, and that a high proportion (>13%) of the aqua-regia extractable contents of several elements (Co, Mn, Ca, Ni, Zn, Sr, Na and B) are mobilised at oxidation. Because of the high quantities of acidity and metals liberated at oxidation, it is argued that stream-water quality, which is poor in the study area, will not improve unless artificial draining is restricted in areas of sulphide sediments.     

Clock-shift experiments with Savannah sparrows, Passerculus sandwichensis, at high northern latitudes

Orientation can be difficult for nocturnal bird migrants at high northern latitudes because of the large changes of magnetic declinations, rapid longitudinal time-shifts experienced during a long-distance flight and the invisibility of stars during the polar summer. Both sunset cues as well as geomagnetic cues have been shown to be of great importance in the orientation system of Savannah sparrows, Passerculus sandwichensis. We used clock-shift experiments to investigate whether geomagnetic and sunset cues were used for migratory orientation by wild-caught young Savannah sparrows at high geomagnetic latitudes in Northern Canada. We exposed birds to a 4-h slow clock-shift, expecting a 60° clock-wise shift in orientation after the treatment. Under natural clear skies in the local geomagnetic field, the birds responded by showing a significant axial mean orientation directed towards the position of the setting sun in the NW and towards their preferred migratory direction in the SE. After exposure to the clock-shift for 6 days and nights the birds showed a clear response to the treatment and shifted significantly towards NNE. Birds that first oriented towards NW in the experiments before clock-shift tended to shift clock-wise, thus reacted to the clock-shift in the expected way. The reaction of the individual birds that originally oriented towards SE seems to vary. In summary, our birds did not select a constant angle (menotaxis) in relation to the sun's position during the experiments, but presumably were affected by the sun showing phototaxis or followed their magnetic compass. Possible explanations of the unexpected experimental results are discussed. Electronic Publication     

Form-specific fragances fromOphrys insectifera L. (Orchidaceae) attract species of different pollinator genera. Evidence of sympatric speciation?

Two closely related forms ofOphrys insectifera were observed in the field to attract different pollinator species selectively.O. i. ssp.insectifera attracted males of two species ofArgogorytes (Sphecidae, Hymenoptera Aculeata) andO. i. ssp.aymoninii attractedAndrena combinata males (Andrenidae, Apoidea, Hymenoptera Aculeata). A third form,O. aff.i. ssp.insectifera, attracted none of these three species. Volatile compounds from flowers and inflorescences of the three forms (originating from Öland, Sweden, and Aveyron, France) were collected, using entrainment, enfleurage, and solvent extraction techniques, and identified by gas chromatography — mass spectrometry. Scent differences between the three forms were confirmed in the amounts of aliphatic hydrocarbons (C₁₁–C₁₉), methyl esters (C₁₄–C₁₈), short chain aliphatic 1-alcohols (C₆–C₁₂), and monoterpene alcohols (C₁₀).     

Decreased PCDD/F formation when co-firing a waste fuel and biomass in a CFB boiler by addition of sulphates or municipal sewage sludge

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are formed during waste incineration and in waste-to-energy boilers. Incomplete combustion, too short residence times at low combustion temperatures (<700 °C), incineration of electronic waste and plastic waste containing chlorine are all factors influencing the formation of PCDD/Fs in boilers. The impact of chlorine and catalysing metals (such as copper and iron) in the fuel on PCDD/F formation was studied in a 12 MW_th circulating fluidised bed (CFB) boiler. The PCDD/F concentrations in the raw gas after the convection pass of the boiler and in the fly ashes were compared. The fuel types were a so-called clean biomass with low content of chlorine, biomass with enhanced content of chlorine from supply of PVC, and solid recovered fuel (SRF) which is a waste fuel containing higher concentrations of both chlorine, and catalysing metals. The PCDD/F formation increased for the biomass with enhanced chlorine content and it was significantly reduced in the raw gas as well as in the fly ashes by injection of ammonium sulphate. A link, the alkali chloride track, is demonstrated between the level of alkali chlorides in the gas phase, the chlorine content in the deposits in the convection pass and finally the PCDD/F formation. The formation of PCDD/Fs was also significantly reduced during co-combustion of SRF with municipal sewage sludge (MSS) compared to when SRF was fired without MSS as additional fuel.