Interacting elevated CO2 and tropospheric O3 predisposes aspen (Populus tremuloides Michx.) to infection by rust (Melampsora medusae f. sp. tremuloidae)

We investigated the interaction of elevated CO₂ and/or (Ozone) O₃ on the occurrence and severity of aspen leaf rust (Melampsora medusae Thuem. f. sp. tremuloidae) on trembling aspen (Populus tremuloides Michx.). Furthermore, we examined the role of changes in leaf surface properties induced by elevated CO₂ and/or O₃ in this host–pathogen interaction. Three‐ to five‐fold increases in levels of rust infection index were found in 2 consecutive years following growing‐season‐long exposures with either O₃ alone or CO₂ + O₃ depending on aspen clone. Examination of leaf surface properties (wax appearance, wax amount, wax chemical composition, leaf surface and wettability) suggested significant effects by O₃ and CO₂ + O₃. We conclude that elevated O₃ is altering aspen leaf surfaces in such a way that it is likely predisposing the plants to increased infection by aspen leaf rust.     

Have recent changes in forest structure reduced the Estonian black stork <Emphasis Type="Italic">Ciconia nigra</Emphasis> population?

The black stork Ciconia nigra is listed as a focal species for guiding forest management in Estonia, where forestry has recently intensified and the stork population has suffered a twofold decline. We explored a possible link between the decline of the population and man-induced changes in forest structure, by analysing nesting of the species in relation to forest cover, edge effects and stand structure. Although the storks had distinct habitat preferences (old remote stands near rivers and a certain distance far from ecotones in well-forested landscapes), these were hardly reflected in site re-occupancy and productivity. Therefore, changes in forest structure are probably not responsible for the population decline, although preferences for specific forest environments may limit the range of potential nest sites. The results indicated that edge avoidance cannot be considered a species-specific feature over large areas and clear habitat preferences are not necessarily related with the present success of a population. We also suggest that lists of focal species should be regularly updated and validated in the field.     

Time-gated luminescence assay using nonmetal probes for determination of protein kinase activity-based disease markers

A novel nonmetal optical probe ARC-1063 whose long-lifetime luminescence is induced by association with the target protein kinase is used for the measurement of the concentration of catalytic subunit of protein kinase A (PKAc) in complicated biological solutions. High affinity (K(D) = 10 pM toward PKAc) and unique optical properties of the probe enable its application for the measurement of picomolar concentrations of PKAc in the presence of high concentrations of other proteins. The described assay is applicable in the high-throughput format with the instrument setups designed for lanthanide-based time-gated (time-resolved) luminescence methods. The assay is used for demonstration that extracellular PKAc (ECPKA) is present in plasma samples of all healthy persons and cancer patients but great care must be taken for procedures of treatment of blood samples to avoid disruption, damage, or activation of platelets in the course of plasma (or serum) preparation and conservation.     

Stomatal and non-stomatal limitation to photosynthesis in two trembling aspen (Populus tremuloides Michx.) clones exposed to elevated CO2 and/or O3

Leaf gas exchange parameters and the content of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) in the leaves of two 2‐year‐old aspen (Populus tremuloides Michx.) clones (no. 216, ozone tolerant and no. 259, ozone sensitive) were determined to estimate the relative stomatal and mesophyll limitations to photosynthesis and to determine how these limitations were altered by exposure to elevated CO₂ and/or O₃. The plants were exposed either to ambient air (control), elevated CO₂ (560 p.p.m.) elevated O₃ (55 p.p.b.) or a mixture of elevated CO₂ and O₃ in a free air CO₂ enrichment (FACE) facility located near Rhinelander, Wisconsin, USA. Light‐saturated photosynthesis and stomatal conductance were measured in all leaves of the current terminal and of two lateral branches (one from the upper and one from the lower canopy) to detect possible age‐related variation in relative stomatal limitation (leaf age is described as a function of leaf plastochron index). Photosynthesis was increased by elevated CO₂ and decreased by O₃ at both control and elevated CO₂. The relative stomatal limitation to photosynthesis (l_s) was in both clones about 10% under control and elevated O₃. Exposure to elevated CO₂ + O₃ in both clones and to elevated CO₂ in clone 259, decreased l_s even further – to about 5%. The corresponding changes in Rubisco content and the stability of C_i/C_a ratio suggest that the changes in photosynthesis in response to elevated CO₂ and O₃ were primarily triggered by altered mesophyll processes in the two aspen clones of contrasting O₃ tolerance. The changes in stomatal conductance seem to be a secondary response, maintaining stable C_i under the given treatment, that indicates close coupling between stomatal and mesophyll processes.     

Soil–plant–atmosphere conditions regulating convective cloud formation above southeastern US pine plantations

Loblolly pine trees (Pinus taeda L.) occupy more than 20% of the forested area in the southern United States, represent more than 50% of the standing pine volume in this region, and remove from the atmosphere about 500 g C m per year through net ecosystem exchange. Hence, their significance as a major regional carbon sink can hardly be disputed. What is disputed is whether the proliferation of young plantations replacing old forest in the southern United States will alter key aspects of the hydrologic cycle, including convective rainfall, which is the focus of the present work. Ecosystem fluxes of sensible () and latent heat (LE) and large‐scale, slowly evolving free atmospheric temperature and water vapor content are known to be first‐order controls on the formation of convective clouds in the atmospheric boundary layer. These controlling processes are here described by a zero‐order analytical model aimed at assessing how plantations of different ages may regulate the persistence and transition of the atmospheric system between cloudy and cloudless conditions. Using the analytical model together with field observations, the roles of ecosystem and LE on convective cloud formation are explored relative to the entrainment of heat and moisture from the free atmosphere. Our results demonstrate that cloudy–cloudless regimes at the land surface are regulated by a nonlinear relation between the Bowen ratio and root‐zone soil water content, suggesting that young/mature pines ecosystems have the ability to recirculate available water (through rainfall predisposition mechanisms). Such nonlinearity was not detected in a much older pine stand, suggesting a higher tolerance to drought but a limited control on boundary layer dynamics. These results enable the generation of hypotheses about the impacts on convective cloud formation driven by afforestation/deforestation and groundwater depletion projected to increase following increased human population in the southeastern United States.     

Isolation and Characterization of a Hantavirus from Lemmus sibiricus: Evidence for Host Switch during Hantavirus Evolution

A novel hantavirus, first detected in Siberian lemmings (Lemmus sibiricus) collected near the Topografov River in the Taymyr Peninsula, Siberia (A. Plyusnin et al., Lancet 347:1835-1836, 1996), was isolated in Vero E6 cells and in laboratory-bred Norwegian lemmings (Lemmus lemmus). The virus, named Topografov virus (TOP), was most closely related to Khabarovsk virus (KBR) and Puumala viruses (PUU). In a cross focus reduction neutralization test, anti-TOP Lemmus antisera showed titers at least fourfold higher with TOP than with other hantaviruses; however, a rabbit anti-KBR antiserum neutralized TOP and KBR at the same titer. The TOP M segment showed 77% nucleotide and 88% amino acid identity with KBR and 76% nucleotide and 82% amino acid identity with PUU. However, the homology between TOP and the KBR S segment was disproportionately higher: 88% at the nucleotide level and 96% at the amino acid level. The 3' noncoding regions of KBR and the TOP S and M segments were alignable except for 113- and 58-nucleotide deletions in KBR. The phylogenetic relationships of TOP, KBR, and PUU and their respective rodent carriers suggest that an exceptional host switch took place during the evolution of these viruses; while TOP and KBR are monophyletic, the respective rodent host species are only distantly related.     

First-Generation Forests Are Not Necessarily Worse than Long-Term Managed Forests for Lichens and Bryophytes

For biodiversity, natural afforestation is generally more favorable than plantation-based afforestation, but the difference may be less important if both methods fail to provide habitats for sensitive old-forest species. Given that some conditions, such as substrates, can be actively restored in new forests, their effect on biodiversity should be separated from dispersal limitation. We asked whether, and to what extent, lichen and bryophyte vegetation is impoverished on old-forest substrates in non-intensively afforested lands of the twentieth century compared with similar substrates in managed long-term forestlands. We measured the diversity and abundance of all lichens and bryophytes as well as the cover of human-sensitive (hemerophobic) species on large deciduous trees, logs, snags, and windthrows on 30 random 2-km transects in a 900-km² forest landscape in Estonia, hemiboreal Europe. Altogether, 235 species, including 39 hemerophobic species, were detected on 781 structural elements. New forests were not significantly worse than long-term forests in any of the cryptogam community characteristics, which was explained by the predominance of natural afforestation (many native tree species present), time for substrate development and cryptogam dispersal (most stands >40 years old), few cuttings in the new forests (only about 20% of stands thinned), and short distances to long-term forests (67% of substrates within 250 m). Under such conditions, afforested areas appeared to be as suitable as traditional managed forests both for developing multifunctional forestry and as starting points for habitat restoration for threatened species.     

Biodiversity of 52 chicken populations assessed by microsatellite typing of DNA pools

In a project on the biodiversity of chickens funded by the European Commission (EC), eight laboratories collaborated to assess the genetic variation within and between 52 populations from a wide range of chicken types. Twenty-two di-nucleotide microsatellite markers were used to genotype DNA pools of 50 birds from each population. The polymorphism measures for the average, the least polymorphic population (inbred C line) and the most polymorphic population (Gallus gallus spadiceus) were, respectively, as follows: number of alleles per locus, per population: 3.5, 1.3 and 5.2; average gene diversity across markers: 0.47, 0.05 and 0.64; and proportion of polymorphic markers: 0.91, 0.25 and 1.0. These were in good agreement with the breeding history of the populations. For instance, unselected populations were found to be more polymorphic than selected breeds such as layers. Thus DNA pools are effective in the preliminary assessment of genetic variation of populations and markers. Mean genetic distance indicates the extent to which a given population shares its genetic diversity with that of the whole tested gene pool and is a useful criterion for conservation of diversity. The distribution of population-specific (private) alleles and the amount of genetic variation shared among populations supports the hypothesis that the red jungle fowl is the main progenitor of the domesticated chicken.     

High-affinity bisubstrate probe for fluorescence anisotropy binding/displacement assays with protein kinases PKA and ROCK

The bisubstrate fluorescent probe ARC-583 (Adc-Ahx-(d-Arg)₆-d-Lys(5-TAMRA)-NH₂) and its application for the characterization of both ATP- and protein/peptide substrate-competitive inhibitors of protein kinases PKA (cyclic AMP-dependent protein kinase) and ROCK (rho kinase) in fluorescence polarization-based assay are described. High affinity of the probe (K_D = 0.48 nM toward PKA) enables its application for the characterization of inhibitors with nanomolar and micromolar potency and determination of the active concentration of the kinase in individual experiments as well as in the high-throughput screening format. The probe can be used for the assessment of protein-protein interactions (e.g., between regulatory and catalytic subunits of PKA) and as a cyclic AMP biosensor.     

Thiazole- and selenazole-comprising high-affinity inhibitors possess bright microsecond-scale photoluminescence in complex with protein kinase CK2

A previously disclosed protein kinase (PK) CK2-selective inhibitor 4-(2-amino-1,3-thiazol-5-yl)benzoic acid (ATB) and its selenium-containing counterpart (ASB) revealed remarkable room temperature phosphorescence when bound to the ATP pocket of the protein kinase CK2. Conjugation of these fragments with a mimic of CK2 substrate peptide resulted in bisubstrate inhibitors with increased affinity towards the kinase. Attachment of the fluorescent acceptor dye 5-TAMRA to the conjugates led to significant enhancement of intensity of long-lifetime (microsecond-scale) photoluminescence of both sulfur- and selenium-containing compounds. The developed photoluminescent probes make possible selective determination of the concentration of CK2 in cell lysates and characterization of CK2 inhibitors by means of time-gated measurement of photoluminescence.