Bird Communities of the Arctic Shrub Tundra of Yamal: Habitat Specialists and Generalists

Background

The ratio of habitat generalists to specialists in birds has been suggested as a good indicator of ecosystem changes due to e.g. climate change and other anthropogenic perturbations. Most studies focusing on this functional component of biodiversity originate, however, from temperate regions. The Eurasian Arctic tundra is currently experiencing an unprecedented combination of climate change, change in grazing pressure by domestic reindeer and growing human activity.

Methodology/Principal Findings

Here we monitored bird communities in a tundra landscape harbouring shrub and open habitats in order to analyse bird habitat relationships and quantify habitat specialization. We used ordination methods to analyse habitat associations and estimated the proportions of specialists in each of the main habitats. Correspondence Analysis identified three main bird communities, inhabiting upland, lowland and dense willow shrubs. We documented a stable structure of communities despite large multiannual variations of bird density (from 90 to 175 pairs/km²). Willow shrub thickets were a hotspot for bird density, but not for species richness. The thickets hosted many specialized species whose main distribution area was south of the tundra.

Conclusion/Significance

If current arctic changes result in a shrubification of the landscape as many studies suggested, we would expect an increase in the overall bird abundance together with an increase of local specialists, since they are associated with willow thickets. The majority of these species have a southern origin and their increase in abundance would represent a strengthening of the boreal component in the southern tundra, perhaps at the expense of species typical of the subarctic zone, which appear to be generalists within this zone.     

An annotated checklist of the horse flies (Diptera: Tabanidae) of Lebanon with remarks on ecology and zoogeography: Pangoniinae and Chrysopsinae

Knowledge of the horse fly fauna (Diptera: Tabanidae) of Lebanon is fragmentary, while the local fauna of most neighboring countries has been fairly well researched. Within the framework of the 20-year project "The ecology and zoogeography of the Lepidoptera of the Near East," we regularly collected biting flies in the whole region, including Lebanon. During this time we recorded 14 horse fly species for two subfamilies in Lebanon: four Pangoniinae and ten Chrysopsinae. Only a single species, Chrysops flavipes Meigen, 1804, was known previously in Lebanon, but the following four Pangoniinae: Pangonius haustellatus (Fabricius, 1781), Pangonius obscuratus Loew, 1859, Pangonius argentatus (Szilady, 1923), and Pangonius fulvipes (Loew, 1859) and nine Chrysopsinae: Silvius appendiculatus Macquart, 1846, Silvius ochraceus Loew, 1858, Nemorius irritans (Ricardo, 1901), Nemorius vitripennis (Meigen, 1820), Chrysops buxtoniAusten, 1922, Chrysops compactusAusten, 1924, Chrysops caecutiens (Linnaeus, 1758), Chrysops italicus Meigen, 1804, and Chrysops hamatus Loew, 1858 are new records for the Lebanese fauna. The Tabanidae fauna of Lebanon is completely Palearctic and most species are of a Mediterranean distribution type. Lebanon or nearby northern Israel appears to be in the Levant, the southern geographical distribution border for the Pangoniinae and Chrysopsinae.     

Potentiation and Block of ASIC1a by Memantine

Acid-sensing ion channels (ASICs) are modulated by various classes of ligands, including the recently described hydrophobic monoamines, which inhibit and potentiate ASICs in a subunit-specific manner. In particular, memantine inhibits ASIC1a and potentiates ASIC2a homomers. The aim of the present work was to characterize action mechanism of memantine on recombinant ASIC1a expressed in CHO (Chinese hamster ovary) cells. We have demonstrated that effect of memantine on ASIC1a strongly depends on membrane voltage, conditioning pH value and application protocol. When applied simultaneously with activating acidification at hyperpolarized voltages, memantine caused the strongest inhibition. Surprisingly, application of memantine between ASIC1a activations at zero voltage caused significant potentiation. Analysis of the data suggests that memantine produces two separate effects, voltage-dependent open-channel block and shift of steady-state desensitization curve to more acidic values. Putative binding sites are discussed based on the computer docking of memantine to the acidic pocket and the pore region.     

Duration and intensity of NF-kappaB activity determine the severity of endotoxin-induced acute lung injury

Activation of innate immunity in the lungs can lead to a self-limited inflammatory response or progress to severe lung injury. We investigated whether specific parameters of NF-kappaB pathway activation determine the outcome of acute lung inflammation using a novel line of transgenic reporter mice. Following a single i.p. injection of Escherichia coli LPS, transient NF-kappaB activation was identified in a variety of lung cell types, and neutrophilic inflammation resolved without substantial tissue injury. However, administration of LPS over 24 h by osmotic pump (LPS pump) implanted into the peritoneum resulted in sustained, widespread NF-kappaB activation and neutrophilic inflammation that culminated in lung injury at 48 h. To determine whether intervention in the NF-kappaB pathway could prevent progression to lung injury in the LPS pump model, we administered a specific IkappaB kinase inhibitor (BMS-345541) to down-regulate NF-kappaB activation following the onset of inflammation. Treatment with BMS-345541 beginning at 20 h after osmotic pump implantation reduced lung NF-kappaB activation, concentration of KC and MIP-2 in lung lavage, neutrophil influx, and lung edema measured at 48 h. Therefore, sustained NF-kappaB activation correlates with severity of lung injury, and interdiction in the NF-kappaB pathway is beneficial even after the onset of lung inflammation.     

Plasticity of the gene functions for DNA replication in the T4-like phages

We have completely sequenced and annotated the genomes of several relatives of the bacteriophage T4, including three coliphages (RB43, RB49 and RB69), three Aeromonas salmonicida phages (44RR2.8t, 25 and 31) and one Aeromonas hydrophila phage (Aeh1). In addition, we have partially sequenced and annotated the T4-like genomes of coliphage RB16 (a close relative of RB43), A. salmonicida phage 65, Acinetobacter johnsonii phage 133 and Vibrio natriegens phage nt-1. Each of these phage genomes exhibited a unique sequence that distinguished it from its relatives, although there were examples of genomes that are very similar to each other. As a group the phages compared here diverge from one another by several criteria, including (a) host range, (b) genome size in the range between approximately 160 kb and approximately 250 kb, (c) content and genetic organization of their T4-like genes for DNA metabolism, (d) mutational drift of the predicted T4-like gene products and their regulatory sites and (e) content of open-reading frames that have no counterparts in T4 or other known organisms (novel ORFs). We have observed a number of DNA rearrangements of the T4 genome type, some exhibiting proximity to putative homing endonuclease genes. Also, we cite and discuss examples of sequence divergence in the predicted sites for protein-protein and protein-nucleic acid interactions of homologues of the T4 DNA replication proteins, with emphasis on the diversity in sequence, molecular form and regulation of the phage-encoded DNA polymerase, gp43. Five of the sequenced phage genomes are predicted to encode split forms of this polymerase. Our studies suggest that the modular construction and plasticity of the T4 genome type and several of its replication proteins may offer resilience to mutation, including DNA rearrangements, and facilitate the adaptation of T4-like phages to different bacterial hosts in nature.     

Stress early in life leads to cognitive impairments,reduced numbers of CA3 neurons and altered maternal behavior in adult female mice

The hippocampus is a crucial part of the limbic system involved both in cognitive processing and in the regulation of responses to stress. Adverse experiences early in life can disrupt hippocampal development and lead to impairment of the hypothalamic‐pituitary‐adrenal axis response to subsequent stressors. In our study, two types of early‐life stress were used: prolonged separation of pups from their mothers (for 3 hours/day, maternal separation, MS) and brief separation (for 15 minutes/day, handling, HD). In the first part of our study, we found that adult female mice (F0) who had experienced MS showed reduced locomotor activity and impairment of long‐term spatial and recognition memory. Analysis of various hippocampal regions showed that MS reduced the number of mature neurons in CA3 of females, which is perhaps a crucial hippocampal region for learning and memory; however, neurogenesis remained unchanged. In the second part, we measured maternal care in female mice with a history of early‐life stress (F0) as well as the behavior of their adult offspring (F1). Our results indicated that MS reduced the level of maternal care in adult females (F0) toward their own progeny and caused sex‐specific changes in the social behavior of adult offspring (F1). In contrast to MS, HD had no influence on female behavior or hippocampal plasticity. Overall, our results suggest that prolonged MS early in life affects the adult behavior of F0 female mice and hippocampal neuronal plasticity, whereas the mothers' previous experience has effects on the behavior of their F1 offspring through disturbances of mother‐infant interactions.     

Label-free optical biosensor with microfluidics for sensing ligand-directed functional selectivity on trafficking of thrombin receptor

Ligand-directed functional selectivity has stimulated much interest in the molecular delineation of drug pharmacology and the process of drug discovery. Here we describe the development of a label-free optical biosensor with microfluidics for whole cell sensing. The microfluidics controls the duration of agonist exposure and of the functional recovery of activated protease activated receptor-1 (PAR(1)). The biosensor manifests that the persistency of PAR(1) signaling is dependent on the agonists, which, in turn, affects the receptor resensitization process. This study demonstrates a new means to differentiate ligand-directed functional selectivity on trafficking of receptors.     

A human monoclonal antibody with neutralizing activity against highly divergent influenza subtypes

The interest in broad-range anti-influenza A monoclonal antibodies (mAbs) has recently been strengthened by the identification of anti-hemagglutinin (HA) mAbs endowed with heterosubtypic neutralizing activity to be used in the design of "universal" prophylactic or therapeutic tools. However, the majority of the single mAbs described to date do not bind and neutralize viral isolates belonging to highly divergent subtypes clustering into the two different HA-based influenza phylogenetic groups: the group 1 including, among others, subtypes H1, H2, H5 and H9 and the group 2 including, among others, H3 subtype. Here, we describe a human mAb, named PN-SIA28, capable of binding and neutralizing all tested isolates belonging to phylogenetic group 1, including H1N1, H2N2, H5N1 and H9N2 subtypes and several isolates belonging to group 2, including H3N2 isolates from the first period of the 1968 pandemic. Therefore, PN-SIA28 is capable of neutralizing isolates belonging to subtypes responsible of all the reported pandemics, as well as other subtypes with pandemic potential. The region recognized by PN-SIA28 has been identified on the stem region of HA and includes residues highly conserved among the different influenza subtypes. A deep characterization of PN-SIA28 features may represent a useful help in the improvement of available anti-influenza therapeutic strategies and can provide new tools for the development of universal vaccinal strategies.     

Methane Emissions from Paludified Boreal Soils in European Russia as Measured and Modelled

Spatial or temporal forest–peatland transition zones were proposed as potential hot spots of methane (CH₄) emissions. Consequently, paludified soils are an important component of boreal landscape biogeochemistry. However, their role in the regional carbon cycle remains unclear. This study presents CH₄ fluxes from two forest–peatland transition zones, two wet forest sites and two clear-cut sites which were compared to fluxes of open peatlands and dry forest. The median fluxes measured using the closed-chamber technique varied from ? 0.04 to 12.6 mg m^?2 h^?1 during three climatically different years. The annual mean CH₄ emissions of the forest–peatland transition zone were significantly lower than the fluxes of the open peatland sites, 7.9 ± 0.5 and 21.9 ± 1.6 g m^?2a^?1, respectively. The dry forest site was characterized by a small uptake of CH₄ (? 2.3 ± 0.2 g m^?2a^?1). Although clear-cut forest area drastically increased in European Russia during the last two decades, if water level depths in these forests remains below 10 cm they do not act as CH₄ sources. Fluxes of CH₄ from the transition zone sites showed a higher response to soil temperature than to water table level. Fluxes of CH₄ between the atmosphere and the two investigated peatlands were not significantly different, although a significant difference in water table level could be observed. The meteorological conditions of the investigated summers changed from being hot and dry in 2013 to cold and wet in 2014; the summer of 2015 was characterized as warmer and drier in the first half and colder and wetter in the second half. Significant differences in CH₄ fluxes were measured only between 2014 and 2013. Significant differences in CH₄ fluxes and in nonlinear regressions showed that the CH₄ fluxes of the different site types such as dry forests, transition zones and open peatlands need to be modelled separately on a landscape level. Obviously, underlying processes vary with the ecosystem and (along with regional aspects) have to be understood first before large-scale modelling is possible.