Declining population trends of European mountain birds

Mountain areas often hold special species communities, and they are high on the list of conservation concern. Global warming and changes in human land use, such as grazing pressure and afforestation, have been suggested to be major threats for biodiversity in the mountain areas, affecting species abundance and causing distribution shifts towards mountaintops. Population shifts towards poles and mountaintops have been documented in several areas, indicating that climate change is one of the key drivers of species’ distribution changes. Despite the high conservation concern, relatively little is known about the population trends of species in mountain areas due to low accessibility and difficult working conditions. Thanks to the recent improvement of bird monitoring schemes around Europe, we can here report a first account of population trends of 44 bird species from four major European mountain regions: Fennoscandia, UK upland, south‐western (Iberia) and south‐central mountains (Alps), covering 12 countries. Overall, the mountain bird species declined significantly (?7%) during 2002–2014, which is similar to the declining rate in common birds in Europe during the same period. Mountain specialists showed a significant ?10% decline in population numbers. The slope for mountain generalists was also negative, but not significantly so. The slopes of specialists and generalists did not differ from each other. Fennoscandian and Iberian populations were on average declining, while in United Kingdom and Alps, trends were nonsignificant. Temperature change or migratory behaviour was not significantly associated with regional population trends of species. Alpine habitats are highly vulnerable to climate change, and this is certainly one of the main drivers of mountain bird population trends. However, observed declines can also be partly linked with local land use practices. More efforts should be undertaken to identify the causes of decline and to increase conservation efforts for these populations.     

Common montane birds are declining in northern Europe

Large‐scale multi‐species data on population changes of alpine or arctic species are largely lacking. At the same time, climate change has been argued to cause poleward and uphill range shifts and the concomitant predicted loss of habitat may have drastic effects on alpine and arctic species. Here we present a multi‐national bird indicator for the Fennoscandian mountain range in northern Europe (Finland, Sweden and Norway), based on 14 common species of montane tundra and subalpine birch forest. The data were collected at 262 alpine survey plots, mainly as a part of geographically representative national breeding bird monitoring schemes. The area sampled covers around 1/4 million km², spanning 10 degrees of latitude and 1600 km in a northeast–southwest direction. During 2002–2012, nine of the 14 bird species declined significantly in numbers, in parallel to higher summer temperatures and precipitation during this period compared to the preceding 40 yr. The population trends were largely parallel in the three countries and similar among montane tundra and subalpine birch forest species. Long‐distance migrants declined less on average than residents and short‐distance migrants. Some potential causes of the current decline of alpine birds are discussed, but since montane bird population sizes may show strong natural annual variation due to several factors, longer time series are needed to verify the observed population trends. The present Fennoscandian monitoring systems, which from 2010 onwards include more than 400 montane survey plots, have the capacity to deliver a robust bird indicator in the climate‐sensitive mountainous regions of northernmost Europe for conservation purposes.     

Energetics,conformation, and recognition of DNA duplexes containing a major adduct of an anticancer azolato-bridged dinuclear Pt complex

Background

The design of anticancer metallodrugs is currently focused on platinum complexes which form on DNA major adducts that cannot readily be removed by DNA repair systems. Hence, antitumor azolato-bridged dinuclear Pt^II complexes, such as [{cis-Pt(NH₃)₂}₂(μ‐OH)(μ-pyrazolate)]²⁺ (AMPZ), have been designed and synthesized. These complexes exhibit markedly higher toxic effects in tumor cell lines than mononuclear conventional cisplatin.

Methods

Biophysical and biochemical aspects of the alterations induced in short DNA duplexes uniquely and site-specifically modified by the major DNA adduct of AMPZ, namely 1,2-GG intrastrand cross-links, were examined. Attention was also paid to conformational distortions induced in DNA by the adducts of AMPZ and cisplatin, associated alterations in the thermodynamic stability of the duplexes, and recognition of these adducts by high-mobility-group (HMG) domain proteins.

Results

Chemical probing of DNA conformation, DNA bending studies and translesion synthesis by DNA polymerase across the platinum adduct revealed that the distortion induced in DNA by the major adduct of AMPZ was significantly less pronounced than that induced by similar cross-links from cisplatin. Concomitantly, the cross-link from AMPZ reduced the thermodynamic stability of the modified duplex considerably less. In addition, HMGB1 protein recognizes major DNA adducts of AMPZ markedly less than those of cisplatin.

General significance

The experimental evidence demonstrates why the major DNA adducts of the new anticancer azolato-bridged dinuclear Pt^II complexes are poor substrates for DNA repair observed in a previously published report. The relative resistance to DNA repair explains why these platinum complexes show major pharmacological advantages over cisplatin in tumor cells.     

Excretome of the chitinolytic bacterium <Emphasis Type="Italic">Clostridium paraputrificum</Emphasis> J4

A strictly anaerobic mesophilic chitinolytic bacterial strain identified as Clostridium paraputrificum J4 was isolated from human feces. In response to various types of growth substrates, the bacterium produced an array of chitinolytic enzymes representing significant components of the J4 strain secretome. The excreted active proteins were characterized by estimating the enzymatic activities of endochitinase, exochitinase, and N-acetylglucosaminidase induced by cultivation in medium M-10 with colloidal chitin. The enzyme activities produced by J4 strain cultivated in medium M-10 with glucose were significantly lower. The spectrum of extracellularly excreted proteins was separated by SDS-PAGE. The chitinase variability was confirmed on zymograms of renatured SDS-PAGE. The enzymes were visualized under ultraviolet light by using 4-methylumbelliferyl derivatives of N-acetyl-β-d-glucosaminide, N,N′-diacetyl-β-d-chitobiose, or N,N′,N˝-triacetyl-β-d-chitotriose for β-N-acetylglucosaminidase, chitobiosidase, or endochitinase activities, respectively. Protein components of the secretome were separated by 2D-PAGE analysis. The distinct protein bands were excised, isolated, and subsequently characterized by using MALDI-TOF/TOF tandem mass spectrometry. The final identification was performed according to sequence homology by database searching.     

Social networks strongly predict the gut microbiota of wild mice

The mammalian gut teems with microbes, yet how hosts acquire these symbionts remains poorly understood. Research in primates suggests that microbes can be picked up via social contact, but the role of social interactions in non-group-living species remains underexplored. Here, we use a passive tracking system to collect high resolution spatiotemporal activity data from wild mice (Apodemus sylvaticus). Social network analysis revealed social association strength to be the strongest predictor of microbiota similarity among individuals, controlling for factors including spatial proximity and kinship, which had far smaller or nonsignificant effects. This social effect was limited to interactions involving males (male-male and male-female), implicating sex-dependent behaviours as driving processes. Social network position also predicted microbiota richness, with well-connected individuals having the most diverse microbiotas. Overall, these findings suggest social contact provides a key transmission pathway for gut symbionts even in relatively asocial mammals, that strongly shapes the adult gut microbiota. This work underlines the potential for individuals to pick up beneficial symbionts as well as pathogens from social interactions.Subject terms: Microbial ecology, Zoology, Community ecology     

SsrA genes of streptomycetes and association of proteins to the tmRNA during development and cellular differentiation

Transfer-messenger RNA (tmRNA, 10Sa RNA, ssrA) is bacterial RNA having both tRNA and mRNA properties and playing an essential role in recycling of 70S ribosomes that are stalled on defective mRNA. The trans-translational system is thought to play a crucial role in bacterial survival under adverse conditions. Streptomycetes are Gram-positive soil bacteria exposed to various physical and chemical stresses that activate specialized responses such as synthesis of antibiotics and morphological differentiation. Comparative sequence analysis of ssrA genes of streptomycetes revealed the most significant differences in the central parts of tag-reading frames, in the stop codons and in the 15-34 nucleotide sequences following stop codons. A major challenge in understanding the interactions that control the function of tmRNA is the definition of protein interactions. Proteins from various phases of development of Streptomyces aureofaciens associated with tmRNA were analyzed. Using affinity chromatography on tmRNA-Sepharose and photo cross-linking experiments with [(32)P]labeled tmRNA seven proteins, the beta and beta'-subunits of DNA dependent RNA polymerase, polyribonucleotide nucleotidyltransferase (PNPase), ribosomal protein SS1, ATP-binding cassette transporters, elongation factor Tu, and SmpB were identified among the proteins associated with tmRNA of S. aureofaciens. We examined the functional role of ribosomal protein SS1 in a defined in vitro trans-translation system. Our data show that the protein SS1 that structurally differs from S1 of Escherichia coli is required for translation of the tmRNA tag-reading frame.     

Antimicrobial effect of oxidized cellulose salts

Antimicrobial properties of oxidized cellulose and its salts in linters (-L) and microsphere (-M) form (OKCEL H-L, OKCEL Zn-M, OKCEL ZnNa-L, OKCEL ZnNa-M and OKCEL Ag-L) were tested by a dilution method against a spectrum of microbial strains: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, Bacillus licheniformis, Aspergillus niger, Penicillium chrysogenum, Rhizopus oryzae, Scopulariopsis brevicaulis, Candida albicans and Candida tropicalis. OKCEL Ag-L exhibited antimicrobial activity in the range 0.1-3.5% w/v against all the bacteria and fungi involved in this study. Strong inhibition by OKCEL ZnNa-M was observed for Staphylococcus epidermidis, Bacillus licheniformis, Rhizopus oryzae, Candida albicans and Candida tropicalis in the range 0.5-2.0% w/v. Antimicrobial effects of oxidized cellulose and its salts in textile form were investigated by a diffusion and dilution method against the spectrum of above-cited microbial strains extended by Clostridium perfringens. Generally, OKCEL Ag-T, OKCEL Zn-T and OKCEL H-T showed high antimicrobial activity against populations of Pseudomonas aeruginosa, Bacillus licheniformis and Staphylococcus epidermidis. OKCEL Zn-T was the only sample suppressing the growth of species.     

Serotonin localization and its functional significance during mouse preimplantation embryo development

Serotonin is a neurotransmitter functioning also as a hormone and growth factor. To further investigate the biological role of serotonin during embryo development, we analysed serotonin localization as well as the expression of specific serotonin 5-HT1D receptor mRNA in mouse oocytes and preimplantation embryos. The functional significance of serotonin during the preimplantation period was examined by studying the effects of serotonin on mouse embryo development. Embryo exposure to serotonin (1 microM) highly significantly reduced the mean cell number, whereas lower concentrations of serotonin (0.1 microM and 0.01 microM) had no significant effects on embryo cell numbers. In all serotonin-treated groups a significant increase in the number of embryos with apoptotic and secondary necrotic nuclei was observed. Expression of serotonin 5-HT1D receptor mRNA in mouse oocytes and preimplantation embryos was confirmed by in situ hybridization showing a clearly distinct punctate signal. Immunocytochemistry results revealed the localization of serotonin in oocytes and embryos to the blastocyst stage as diffuse punctate cytoplasmic labelling. It appears that endogenous and/or exogenous serotonin in preimplantation embryos could be involved in complex autocrine/paracrine regulations of embryo development and embryo-maternal interactions.     

Heavy browsing affects the hydraulic capacity of Ceanothus rigidus (Rhamnaceae)

Defoliation by herbivores can reduce carbon assimilation, change plant water relations, and even shift the biotic structure of plant communities. In this study, we took advantage of a long-term deer exclosure experiment to examine the consequences of persistent deer herbivory on plant water relations and the xylem structure–function relationships in Ceanothus rigidus, a maritime chaparral shrub in coastal California. Browsed plants had thicker stems with many intertwined short distal twigs, and significantly higher sapwood-to-leaf area ratios than their non-browsed counterparts. Leaf area-specific hydraulic conductivity was similar in both browsed and non-browsed plants, but xylem area-specific conductivity was significantly lower in the browsed plants. Vessel diameters were equivalent in both plant groups, but the number of vessels on a transverse area basis was nearly 40 % lower in the browsed plants, accounting for their lower transport efficiency. Mid-day in situ water potentials and losses of hydraulic conductivity due to embolism were similar in both groups of plants but stomatal conductance was higher in the browsed shrubs in the early part of the growing season. We discuss our findings in the context of whole-plant ecophysiology, and explore the consequences of herbivory on hormonal signals, wood anatomy, and xylem function.