Spatial Genetic Structure of the Abundant and Widespread Peatmoss Sphagnum magellanicum Brid.

Spore-producing organisms have small dispersal units enabling them to become widespread across continents. However, barriers to gene flow and cryptic speciation may exist. The common, haploid peatmoss Sphagnum magellanicum occurs in both the Northern and Southern hemisphere, and is commonly used as a model in studies of peatland ecology and peatmoss physiology. Even though it will likely act as a rich source in functional genomics studies in years to come, surprisingly little is known about levels of genetic variability and structuring in this species. Here, we assess for the first time how genetic variation in S. magellanicum is spatially structured across its full distribution range (Northern Hemisphere and South America). The morphologically similar species S. alaskense was included for comparison. In total, 195 plants were genotyped at 15 microsatellite loci. Sequences from two plastid loci (trnG and trnL) were obtained from 30 samples. Our results show that S. alaskense and almost all plants of S. magellanicum in the northern Pacific area are diploids and share the same gene pool. Haploid plants occur in South America, Europe, eastern North America, western North America, and southern Asia, and five genetically differentiated groups with different distribution ranges were found. Our results indicate that S. magellanicum consists of several distinct genetic groups, seemingly with little or no gene flow among them. Noteworthy, the geographical separation of diploids and haploids is strikingly similar to patterns found within other haploid Sphagnum species spanning the Northern Hemisphere. Our results confirm a genetic division between the Beringian and the Atlantic that seems to be a general pattern in Sphagnum taxa. The pattern of strong genetic population structuring throughout the distribution range of morphologically similar plants need to be considered in future functional genomic studies of S. magellanicum.     

Reduced immunocompetence and cost of reproduction in common eiders

Immunocompetence may be especially important in long-lived species where infectious organisms may have detrimental effects upon future reproductive value of hosts. The resource demand for immunocompetence may reduce resource availability for reproduction and a trade-off between these traits has therefore been proposed. Capital breeders, such as the common eider (Somateria mollissima), rely upon accumulated body reserves during reproduction. Eiders lose more than 40% of pre-breeding body mass during egglaying and incubation and many females abandon their ducklings to other females after hatching. Results from our observational study show that levels of leukocytes (i.e., lymphocytes, heterophils and heterophil/lymphocyte ratio) are not related to body mass early in the incubation period. However, eider females with low initial body mass showed signs of immunosuppression (i.e., decreased late levels of lymphocytes) and increased response towards stressors (i.e., increased heterophil/lymphocyte ratio) later in the incubation period. Moreover, females with low lymphocyte levels more frequently abandoned their brood, and females abandoning young had an increased return rate to the next breeding season. However, among brood abandoning females return rate was lower for the females with low lymphocyte levels. These results suggest that immunosuppression, as indicated by low lymphocyte levels, is a reproductive cost that may be partly compensated for by abandoning young.     

Discovery of a novel series of quinolone α7 nicotinic acetylcholine receptor agonists

High throughput screening led to the identification of a novel series of quinolone α7 nicotinic acetylcholine receptor (nAChR) agonists. Optimization of an HTS hit (1) led to 4-phenyl-1-(quinuclidin-3-ylmethyl)quinolin-2(1H)-one, which was found to be potent and selective. Poor brain penetrance in this series was attributed to transporter-mediated efflux, which was in turn due to high pK_a. A novel 4-fluoroquinuclidine significantly lowered the pK_a of the quinuclidine moiety, reducing efflux as measured by a Caco-2 assay.     

A Prospective Population Study of Resting Heart Rate and Peak Oxygen Uptake (the HUNT Study,Norway)

Objectives

We assessed the prospective association of resting heart rate (RHR) at baseline with peak oxygen uptake (VO_2peak) 23 years later, and evaluated whether physical activity (PA) could modify this association.

Background

Both RHR and VO_2peak are strong and independent predictors of cardiovascular morbidity and mortality. However, the association of RHR with VO_2peak and modifying effect of PA have not been prospectively assessed in population studies.

Methods

In 807 men and 810 women free from cardiovascular disease both at baseline (1984–86) and follow-up 23 years later, RHR was recorded at both occasions, and VO_2peak was measured by ergospirometry at follow-up. We used Generalized Linear Models to assess the association of baseline RHR with VO_2peak, and to study combined effects of RHR and self-reported PA on later VO_2peak.

Results

There was an inverse association of RHR at baseline with VO_2peak (p<0.01). Men and women with baseline RHR greater than 80 bpm had 4.6 mL·kg⁻¹·min⁻¹ (95% confidence interval [CI], 2.8 to 6.3) and 1.4 mL·kg⁻¹·min⁻¹ (95% CI, −0.4 to 3.1) lower VO_2peak at follow-up compared with men and women with RHR below 60 bpm at baseline. We found a linear association of change in RHR with VO_2peak (p = 0.03), suggesting that a decrease in RHR over time is likely to be beneficial for cardiovascular fitness. Participants with low RHR and high PA at baseline had higher VO_2peak than inactive people with relatively high RHR. However, among participants with relatively high RHR and high PA at baseline, VO_2peak was similar to inactive people with relatively low RHR.

Conclusion

RHR is an important predictor of VO_2peak, and serial assessments of RHR may provide useful and inexpensive information on cardiovascular fitness. The results suggest that high levels of PA may compensate for the lower VO_2peak associated with a high RHR.     

Contribution of rare and common species to richness patterns at local scales

Several studies have recently reported that common species are more important for species richness patterns than rare species. However, most such studies have been based on broad‐scale atlas data. We studied the contribution of different species occupancy, i.e. number of plots occupied, to species richness patterns emerging from species data in 50 by 50 m plots within six 140–200 ha forests in Norway. The study included vascular plants, lichens, bryophytes, and polypore fungi. We addressed the following questions: 1) are common species more correlated with species richness than rare species? 2) How do occupancy classes combine at various levels of species richness? 3) Which occupancy class is best in identifying the overall most species‐rich sites (hotspots) by sampling? The results showed that rare species were better correlated with species richness than common species when the information content was accounted for, that high species richness was associated with a higher proportion of less frequent species, and that the best occupancy class for local hotspot identification was species present in 10–30% of the plots within a forest. We argue that the observed correlations between overall richness and sub‐assembly richness are primarily structured by the combination of the distributions of species richness and species occupancy. Although these distributions result from general ecological processes, they may also be strongly affected by idiosyncratic elements of the individual datasets caused by the specific environmental composition of a study area. Hence, different datasets collected in different areas may lead to different results regarding the relative importance of common versus rare species, and such effects should be expected on both broad and fine spatial scales. Despite these effects, we suggest that infrequent species will tend to be more strongly correlated to species richness at local scales than at broader scales as a result of more right‐skewed species‐occupancy distributions.     

Growth and mortality of Arctic charr and European whitefish reared at low temperatures

This comparative study explores how low temperatures affect the mortality and growth of first generation hatchery-reared progeny of subarctic populations of Arctic charr (Salvelinus alpinus L.) and European whitefish (Coregonus lavaretus L.). Replicate fish groups where held under simulated natural light regimes (70°N) at three constant temperatures (1, 3 and 6°C). The mortality of Arctic charr was low (≤1.4%) at all temperature treatments, whereas the mortality of whitefish increased with decreasing temperature from 6% at 6°C to 33% at 1°C. The Arctic charr exhibited higher growth rates than whitefish at all three temperature regimes. All groups of Arctic charr increased in weight, whereas whitefish held at 1°C did not gain weight throughout the experimental period of 133 days. Arctic charr exhibited a large intraspecific variability in growth leading to large variations in size-structure, whereas whitefish in contrast showed very homogenous growth and size-structure patterns; a dissimilarity probably related to species-specific differences in antagonistic behaviour. Evidently, Arctic charr are more cold water adapted than whitefish and are able to maintain growth at extremely low temperatures. Arctic charr thus appear to be the most suitable species for aquaculture at low water temperatures.     

DARPP-32 and Phosphatase Inhibitor-1, Two Structurally Related Inhibitors of Protein Phosphatase-1, Are Both Present in Striatonigral Neurons

DARPP-32 (dopamine- and cyclic AMP-regulated phosphoprotein of Mr = 32,000) and phosphatase inhibitor-1, two previously characterized inhibitors of protein phosphatase-1, were identified in both the neostriatum and the substantia nigra. Phosphatase inhibitor-1 was partially purified from bovine caudate nucleus and found to be distinct from DARPP-32 in some of its biochemical properties. The neuronal localization of DARPP-32 and phosphatase inhibitor-1 within the rat neostriatum and substantia nigra was investigated by studying the effects of kainic acid. Injection into the neostriatum of kainic acid, which destroys striatonigral neurons and striatonigral fibers, decreased the amounts of DARPP-32 and phosphatase inhibitor-1 to the same extent, both in the lesioned neostriatum and in the ipsilateral substantia nigra. The specific activity of protein phosphatase-1 in the neostriatum was unaffected by kainic acid. The results indicate that, in rat brain, DARPP-32 and phosphatase inhibitor-1 are both present in striatal neurons and in striatonigral fibers, and that they probably coexist in at least a subpopulation of striatonigral neurons. In contrast, protein phosphatase-1 does not appear to be enriched in any specific neuronal subpopulation in the neostriatum.     

Analyses of ribosomal proteins from mycobacteria with particular reference to the β antigen

Abstract The proteins of the ribosomal subunits of Mycobacterium phlei were analysed by sodium dodecylsulphate (SDS)-polyacrylamide gel electrophoresis (PAGE) and by 2-dimensional PAGE. These techniques revealed that both the size and the charge of the mycobacterial ribosomal proteins were quite different from those of Escherichia coli . The divergent chemical properties of the mycobacterial ribosomes might be related to other exceptional properties of mycobacteria, e.g., their slow growth. An antigen designated β was furthermore revealed in both 30S and 50S subunits of M. phlei and Mycobacterium bovis BCG. 2 Proteins from each subunit migrated in a similar way in SDS-PAGE, being thus prime candidates as carriers of β-activity.