Genetic analysis of four Île Amsterdam Sphagna: high morphological divergence within Sphagnum subgenus Subsecunda

This study uses microsatellites (SSRs) and nucleotide sequences to explore unresolved questions associated with four of the six Sphagnum species reported for Île Amsterdam: Sphagnum cavernulosum of unknown subgenus, S. complanatum and S. islei of subg. Subsecunda, and plants that initial morphological study placed in subg. Cuspidata. Genetic analyses show that all four species belong to subgenus Subsecunda and that none are allopolyploids. The plants initially placed in subg. Cuspidata are shown to belong to the ‘S. africanum’ clade of subg. Subsecunda and are closest to the African S. truncatum based on morphology. Sphagnum cavernulosum, S. complanatum, and S. islei are part of the Afro-Australasian clade of subg. Subsecunda, with S. complanatum and S. islei being closely associated with the African ‘S. capense’ complex and S. cavernulosum, which is morphologically divergent from all extant subgenera in the genus, being an outlier within this clade. Preliminary genetic analyses show S. islei to be closely related to S. complanatum and that they may represent two morphologically divergent genets of one species. The ancestral origins for the Île Amsterdam populations of S. complanatum, S. islei, and S. cf. truncatum are each ultimately based in Africa. Further study is required to determine the ecological and evolutionary significance, if any, provided by the pronounced morphological variation within species and the high morphological divergence among species in subg. Subsecunda. Finally, a prior report of S. recurvum (subg. Cuspidata) possibly occurring on Île Amsterdam is concluded to have been based on laboratory error.     

Nutrient dynamics of reindeer forage species along snowmelt gradients at different ecological scales

Growing season nutrient dynamics of four reindeer forage species (Betula nana, Eriophorum angustifolium, Rumex acetosa and Vaccinium myrtillus) were studied in a mountainous sub-arctic landscape in N Sweden. Changes in nitrogen (N), phosphorus (P) and fibre (ADF) concentrations in leaves and shoots were analysed (from a reindeer foraging perspective) along four ecological gradients significant to regional and local snowmelt regimes: season, oceanicity, altitude, and snow-patch retreat. N and P concentrations showed marked seasonal variations with peaks occurring from the middle of June to the end of July depending on species and snowmelt progression. The seasonal pattern for ADF concentrations, as well as differences between snowmelt regimes, were less consistent and showed large differences between species. N concentrations increased along snowmelt gradients at small (within snow-patches) and medium (along altitude gradients) spatial scales. Furthermore, variations in N concentrations were temporally and spatially scale-dependent, which underlines the importance of scale for understanding plant nutrient dynamics in sub-arctic and alpine systems, as well for plant–animal interactions. The greatest temporal and spatial differences in nutrient quality were observed early in the season, i.e., at the time of highest nutrient requirements for reindeer. Climate-induced changes of the start and the progress of the growing season may result in significant consequences to the development of calves and subsequently to the population demography of reindeer, mediated through spatial and temporal changes in the distribution of high quality food. These results provide basic knowledge for reindeer management in the light of the ongoing global warming.     

Foraging activity patterns in the goosander (Mergus merganser) and the red-breasted merganser (M. serrator) in relation to patterns of activity in their major prey species

Summary Diel and seasonal foraging activity patterns of goosanders (Mergus merganser L.) and red-breasted mergansers (M. serrator L.) were studied during the breeding season on the Rickleå River in northern Sweden (64°05N). In addition, the locomotor activity patterns of their most important prey species, the river lamprey (Lampetra fluviatilis (L.)) and the three-spined stickleback (Gasterosteus aculeatus L.), were recorded.During spring, as mergansers arrived in the breeding area, both species exhibited a bimodal, diurnal pattern of activity with morning and evening peaks. By June (the spawning period for the river lamprey and the migratory period for the three-spined stickleback), goosander activity had shifted to late in the evening. This new activity peak correlated well with the main activity period in the river lamprey. Red-breasted mergansers remained predominantly diurnal throughout the observation period. Their diurnal activity correlated with the activity of their major prey, the three-spined stickleback.Both merganser species utilize a specialized foraging technique, i.e. probing the river-bottom with the bill, to catch hiding fish more or less at random. This behaviour probably helps them to forage during the relatively bright summer nights and thus prey upon the abundant nocturnal river lamprey. The goosander preys upon the river lamprey to a greater extent than does the red-breasted merganser, thus leading to a temporal segregation in food resource utilization between the two duck species.     

Microcarrier culture of recombinant Chinese hamster ovary cells for production of human immune interferon and human tissue-type plasminogen activator

Summary Recombinant Chinese hamster ovary cells were successfully cultured semi-continuously on microcarriers of gelatin or modified dextran under non-selective conditions for up to three weeks. High and constant production rates for human immune interferon and tissue-type plasminogen activator were obtained. For cells that produced interferon, the highest cell concentration and interferon production was obtained with gelatin microcarriers though the specific production when grown in the presence of 0.2% fetal calf serum was slightly higher for cells cultured on dextran microcarriers (0.12 U/cell day versus 0.11 U/cell day). For cells that produced plasminogen activator, a slightly higher cell concentration was obtained for cells grown on dextran microcarriers (9x10⁵ cells/ml versus 7x10⁵ cells/ml). However, the specific and total production rates were significantly higher for cells cultured on gelatin microcarriers (6.7 pg/cell day versus 2.1 pg/cell day). The maximum cell concentration and specific production rate could be increased to 2.3x10⁶ cells/ml and 3.4 pg/cell day for dextran microcarriers by adding 6-aminohexanoic acid to the medium. For gelatin microcarriers, the addition of 6-aminohexanoic acid increased the specific production rate to 14.4 pg/cell day. Cell growth, however, was inhibited.     

Do intruding predators and trap position affect the reliability of catches in activity traps?

Forty lakes in Sweden and Finland were sampled in 1990 with activity traps to evaluate the effects of trapped predators on invertebrate catch. Vertebrate (fish, newts) and invertebrate (leeches, dragonflies, water beetles, backswimmers and water scorpions) predators were considered separately. Invertebrate predators affected neither the abundance nor the taxonomic diversity of the catches. Vertebrate predators had no effect on the abundance but reduced the taxonomic diversity of the catches significantly. Thus, vertebrate predators are a possible source of bias in activity trap catches, but only concerning taxonomic diversity. Within the depth gradient studied (0.25–0.75 m), trap position (suspended in mid-water versus on the bottom) did not affect the percentages of nektonic and benthic invertebrates in the catches. The relative abundance of all taxa was similar in the catches from different trap positions, but the relative abundance of the most numerous taxa as well as the diversity of the catches differed between trap positions. We conclude that both mid-water and bottom traps are suitable for monitoring aquatic invertebrates, and that bottom traps may be preferred for practical reasons.     

Neuronal adenosine A<Subscript>2A</Subscript> receptor overexpression is neuroprotective towards 3-nitropropionic acid-induced striatal toxicity: a rat model of Huntington’s disease

The A_2A adenosine receptor (A_2AR) is widely distributed on different cellular types in the brain, where it exerts a broad spectrum of pathophysiological functions, and for which a role in different neurodegenerative diseases has been hypothesized or demonstrated. To investigate the role of neuronal A_2ARs in neurodegeneration, we evaluated in vitro and in vivo the effect of the neurotoxin 3-nitropropionic acid (3-NP) in a transgenic rat strain overexpressing A_2ARs under the control of the neural-specific enolase promoter (NSEA_2A rats). We recorded extracellular field potentials (FP) in corticostriatal slice and found that the synaptotoxic effect of 3-NP was significantly reduced in NSEA_2A rats compared with wild-type animals (WT). In addition, after exposing corticostriatal slices to 3-NP 10 mM for 2 h, we found that striatal cell viability was significantly higher in NSEA_2A rats compared to control rats. These in vitro results were confirmed by in vivo experiments: daily treatment of female rats with 3-NP 10 mg/kg for 8 days induced a selective bilateral lesion in the striatum, which was significantly reduced in NSEA_2A compared to WT rats. These results demonstrate that the overexpression of the A_2AR selectively at the neuronal level reduced 3-NP-induced neurodegeneration, and suggest an important function of the neuronal A_2AR in the modulation of neurodegeneration.     

Left posterior fascicular block,state-of-the-art review: A 2018 update

We conducted a review of the literature regarding epidemiology, clinical, electrocardiographic and vectorcardiographic aspects, classification, and differential diagnosis of left posterior fascicular block.Isolated left posterior fascicular block (LPFB) is an extremely rare finding both in the general population and in specific patient groups. In isolated LPFB 20% of the vectorcardiographic (VCG) QRS loop is located in the right inferior quadrant and when associated with right bundle branch block (RBBB) ≥40%.The diagnosis of LPFB should always consider the clinical aspects, because a definite diagnosis cannot be made in the presence of right ventricular hypertrophy (RVH) (chronic obstructive pulmonary disease (COPD)/emphysema), extensive lateral myocardial infarction (MI) or extremely vertical heart.Intermittent LPFBs are never complete blocks (transient or second degree LPFB) and even in the permanent ones, one cannot be sure that they are complete. When LPFB is associated with RBBB and acute inferior MI, PR interval prolongation is very frequent.     

Influence of season and diet on liver and kidney content of essential elements and heavy metals in svalbard reindeer

Samples of liver (n=78) and kidney (n=60) from Svalbard reindeer (Rangifer tarandus platyrhynchus Vrolik) collected at four different seasons in Svalbard were analysed for their content of Cd, Pb, Cu, Zn, Mn, and Se. The study shows that when animals are exposed to large seasonal variations in both the quality and quantity of food, it is crucial to relate element concentrations to the physiological condition of the animal, e.g., to look at seasonal fluctuations in the total element content of the different organs. Deceased January 9, 1991.     

Freeze-resistant Trichinella (Trichinella nativa) Established on the Scandinavian Peninsula

Until the 1970’s, Trichinella spiralis (Owen 1835) was considered the only species within the genus Trichinella. Then T. pseudospiralis (Garkavi 1972) was classified as a separate species on the basis of morphological and biological features. The remaining morphologically homogenous “T. spiralis-group” has been split into 4 different species (or subspecies) on the basis of their biological and biochemical characteristics; T. nativa (Britov & Boev 1972), T. nelsoni (Britov & Boev 1972), T. spiralis sensu stricto and T. britovi (Pozio et al. 1992).     

Cloning, structural analysis, and expression of the pig IgE ε chain

 As a step in the evolutionary studies of immunoglobulin E (IgE) and for the purpose of developing new reagents that will facilitate a more detailed analysis of IgE-mediated inflammatory reactions in a large animal model, we here present the cloning of the ε chain of IgE in the domestic pig (Sus scrufa). A partial cDNA clone for the ε chain of pig IgE was isolated by polymerase chain reaction (PCR) amplification using degenerate primers directed against conserved regions in the second (CH2) and the fourth (CH4) constant domains of IgE. cDNA derived from mRNA isolated from the spleen and lymph nodes of a pig actively sensitized with a protein extract from the nematode Ascaris suum was used as template. Screening of a spleen cDNA library with the partial cDNA clone as probe resulted in isolation of a clone that contained the entire coding region. The nucleotide sequence was determined and was found to conform with the previously identified mammalian ε-chain sequences. The highest degree of similarity was found to sheep IgE. A DNA construct encoding a baculovirus signal sequence, a histidine hexapeptide, and the CH2-CH3-CH4 domains of the pig IgE ε chain was obtained by PCR amplification. The construct was ligated into the baculovirus expression vector pVL1392. Infection of High Five insect cells with recombinant baculovirus resulted in expression and secretion of a soluble 6 × His-CH2-CH3-CH4 protein product. Received: 9 April 1997 / Revised: 28 May 1997