Ontogenetic change in effectiveness of chemical defence against different predators in Oxycarenus true bugs

Many prey species change their antipredator defence during ontogeny, which may be connected to different potential predators over the life cycle of the prey. To test this hypothesis, we compared reactions of two predator taxa – spiders and birds – to larvae and adults of two invasive true bug species, Oxycarenus hyalinipennis and Oxycarenus lavaterae (Heteroptera: Oxycarenidae) with life-stage-specific chemical defence mechanisms. The reactions to larvae and adults of both true bug species strikingly differed between the two predator taxa. The spiders were deterred by the defences of adult bugs, but the larval defences were ineffective against them. By contrast, birds attacked the larvae considerably less often than the adult bugs. The results indicate a predator-specific ontogenetic change in defence effectiveness of both Oxycarenus species. The change in defence is likely linked to the life-stage-specific composition of secretions in both species: whereas secretions of larvae are dominated by unsaturated aldehydes, secretions of adults are rich in terpenoids, which probably serve dual function of defensive chemicals and pheromones. Our results highlight the variation in defence between different life stages and the importance of testing responses of different types of predators.     

Ectomycorrhizal diversity on the roots of Pitch pine (Pinus rigida Mill.) saplings as influenced by remediation and soil metal content

From 1913 to 1980, two zinc smelters in Palmerton, Pennsylvania, emitted large quantities of atmospheric pollutants nearly eliminating forests along a ridge above the town. In 2008, a remediation treatment was applied to the land above one of the smelters that included the planting of several locally adapted plant species. It also included mineral fertilization and mycorrhizal inoculation. One of the species, the Pitch pine (Pinus rigida, Mill.), is a native tree that is both tolerant of metalliferous soils and obligatorily ectomycorrhizal. This report summarizes the results of two observational studies conducted 5 years after the remediation treatment. The first study's objective was to compare ectomycorrhizal communities on treated Pitch pine saplings, with communities on naturally regenerating saplings in an adjacent non-remediated area. The second study's objective was to determine if the composition of the fungal communities on root tips of naturally regenerating Pitch pine saplings differed with distance from the smelters. Fungal community compositions were determined using internal transcribed spacer rRNA sequences. Comparisons of sequences from the remediated and non-remediated sites revealed that communities at the remediated sites had lower taxonomic diversity and were dominated by members of a genus in the remediation inoculant. The results of the smelter-proximity study indicated that although fungal diversity did not differ markedly with distance from the smelters, the relative abundances of some taxa were greater on saplings growing directly above the smelters, where the soils contained highest concentrations of zinc and cadmium.     

Decomposing trends in bird populations: Climate,life histories and habitat affect different aspects of population change

Aim

Despite the complexity of population dynamics, most studies concerning current changes in bird populations reduce the trajectory of population change to a linear trend. This may hide more complex patterns reflecting responses of bird populations to changing anthropogenic pressures. Here, we address this complexity by means of multivariate analysis and attribute different components of bird population dynamics to different potential drivers.

Location

Czech Republic.

Methods

We used data on population trajectories (1982–2019) of 111 common breeding bird species, decomposed them into independent components by means of the principal component analysis (PCA), and related these components to multiple potential drivers comprising climate, land use change and species' life histories.

Results

The first two ordination axes explained substantial proportion of variability of population dynamics (42.0 and 12.5% of variation in PC1 and PC2 respectively). The first axis captured linear population trend. Species with increasing populations were characterized mostly by long lifespan and warmer climatic niches. The effect of habitat was less pronounced but still significant, with negative trends being typical for farmland birds, while positive trends characterized birds of deciduous forests. The second axis captured the contrast between hump-shaped and U-shaped population trajectories and was even more strongly associated with species traits. Species migrating longer distances and species with narrower temperature niches revealed hump-shaped population trends, so that their populations mostly increased before 2000 and then declined. These patterns are supported by the trends of total abundances of respective ecological groups.

Main Conclusion

Although habitat transformation apparently drives population trajectories in some species groups, climate change and associated species traits represent crucial drivers of complex population dynamics of central European birds. Decomposing population dynamics into separate components brings unique insights into non-trivial patterns of population change and their drivers, and may potentially indicate changes in the regime of anthropogenic effects on biodiversity.     

Glucoamylases encoded by variantSaccharomycopsis fibuligera genes: Structure and properties

The genes of two variant glucoamylases (GLA1 and GLU1) ofSaccharomycopsis fibuligera were expressed inSaccharomyces cerevisiae, and biochemical properties of the secreted enzymes were compared. It was found that three amino acid alterations in the signal peptide and N-terminal regions of the variants had no effect on the levels of the secreted enzymes. Amino acid alterations in the C-terminal region of the mature proteins influenced their specific activity, substrate specificity, as well as temperature and pH optima. Because of the glycosylation heterogeneity, the glucoamylases of each gene variant were isolated and purified in two forms (A and B), which were essentially similar in catalytic and physicochemical properties but differed in their thermal stability and ability to renaturate after thermal denaturation.     

Incidence and genetic diversity of raspberry bushy dwarf virus (RBDV) in Rubus spp. in Turkey

Raspberry bushy dwarf virus (RBDV), recently renamed to Idaeovirus rubi, is one of the most common viruses infecting Rubus species worldwide but there is still a limited number of genome sequences available in the GenBank database and the majority of the sequences include partial sequences of RNA-1 and RNA-2. The distribution and incidence of RBDV in main raspberry and blackberry growing provinces in Turkey were monitored during 2015–2019 and 537 Rubus spp. samples were tested by both DAS-ELISA and RT-PCR. Among the tested samples, 36 samples tested positive for RBDV by DAS-ELISA and 67 samples by RT-PCR. There was relatively low nucleotide diversity among the Turkish isolates. Turkish isolates shared 93%–97.7%, 84.3%–98.9%, and 85%–99.2% nucleotide sequence identities with available sequences in the GenBank, in partial RNA-1, movement protein (MP) and coat protein (CP) genes, respectively. In the phylogenetic tree constructed for RNA-1, MP, and CP sequences, all Turkish raspberry isolates were clustered in a distinct clade. However, the blackberry isolates showed considerable variation in nucleotide sequences and were placed in three distinct groups. The divergent blackberry isolates showed high variability in MP (84.5%–89.3%) and CP (85.5%–89.7%) regions and were placed in a distinct group. The rest of blackberry isolates clustered together with sweet cherry RBDV isolates adjacent to the grapevine clade or together with raspberry isolates. The comparative analysis conducted on three RNA segments of RBDV highlighted the high sequence diversity of Turkish RBDV isolates. This study also emphasizes the importance of regular monitoring of RBDV infections in Turkey, with special regard to those Rubus spp. and grapevine accessions employed in conservation and selection programmes. In particular, the presence of new RBDV genetic variants and infection of Rubus species must be taken into account to choose a correct detection protocol and management strategy.     

Experimental evidence of size-selective harvest and environmental stochasticity effects on population demography,fluctuations and non-linearity

Theory and analyses of fisheries data sets indicate that harvesting can alter population structure and destabilise non-linear processes, which increases population fluctuations. We conducted a factorial experiment on the population dynamics of Daphnia magna in relation to size-selective harvesting and stochasticity of food supply. Harvesting and stochasticity treatments both increased population fluctuations. Timeseries analysis indicated that fluctuations in control populations were non-linear, and non-linearity increased substantially in response to harvesting. Both harvesting and stochasticity induced population juvenescence, but harvesting did so via the depletion of adults, whereas stochasticity increased the abundance of juveniles. A fitted fisheries model indicated that harvesting shifted populations towards higher reproductive rates and larger-magnitude damped oscillations that amplify demographic noise. These findings provide experimental evidence that harvesting increases the non-linearity of population fluctuations and that both harvesting and stochasticity increase population variability and juvenescence.     

Quality Assessment of Bee Pollen-Honey Mixtures Using Thin-Layer Chromatography in Combination with Chemometrics

The aim of this study is to develop a rapid, effect-directed screening method for quality assessment of bee pollen-honey mixtures. The comparative antioxidant potential and phenolic content of honey, bee pollen, and the bee pollen-honey mixtures, was performed using spectrophotometry. The total phenolic content and antioxidative activity of bee pollen-honey mixtures with 20 % bee pollen share were in the range 3.03–3.11 mg GAE/g, and 6.02–6.96 mmol TE/kg, respectively, while mixtures with 30 % bee pollen share contained 3.92–4.18 mg GAE/g, and 9.69–10.11 mmol TE/kg. Chromatographic fingerprint of bee pollen-honey mixtures was performed by high-performance thin-layer chromatography with conditions developed by authors and reported for the first time. Fingerprint analysis hyphenated with chemometrics enabled authenticity assessments of honey in mixtures. Results indicate that bee pollen-honey mixtures represent a food with highly, both, nutritious characteristics and health-promoting effect.     

Novel Miscanthus hybrids: Modelling productivity on marginal land in Europe using dynamics of canopy development determined by light interception

New biomass crop hybrids for bioeconomic expansion require yield projections to determine their potential for strategic land use planning in the face of global challenges. Our biomass growth simulation incorporates radiation interception and conversion efficiency. Models often use leaf area to predict interception which is demanding to determine accurately, so instead we use low-cost rapid light interception measurements using a simple laboratory-made line ceptometer and relate the dynamics of canopy closure to thermal time, and to measurements of biomass. We apply the model to project the European biomass potentials of new market-ready hybrids for 2020–2030. Field measurements are easier to collect, the calibration is seasonally dynamic and reduces influence of weather variation between field sites. The model obtained is conservative, being calibrated by crops of varying establishment and varying maturity on less productive (marginal) land. This results in conservative projections of miscanthus hybrids for 2020–2030 based on 10% land use conversion of the least (productive) grassland and arable for farm diversification, which show a European potential of 80.7–89.7 Mt year⁻¹ biomass, with potential for 1.2–1.3 EJ year⁻¹ energy and 36.3–40.3 Mt year⁻¹ carbon capture, with seeded Miscanthus sacchariflorus × sinensis displaying highest yield potential. Simulated biomass projections must be viewed in light of the field measurements on less productive land with high soil water deficits. We are attempting to model the results from an ambitious and novel project combining new hybrids across Europe with agronomy which has not been perfected on less productive sites. Nevertheless, at the time of energy sourcing issues, seed-propagated miscanthus hybrids for the upscaled provision of bioenergy offer an alternative source of renewable energy. If European countries provide incentives for growers to invest, seeded hybrids can improve product availability and biomass yields over the current commercial miscanthus variety.     

Cultivation of lymphatic cells in protein-free medium and chemical study of the products

Rabbits immunized withBrucella suis within a period of one week formed antibodies in high titres. These antibodies were of a macroglobulin character only. Cells from the spleen and popliteal lymph nodes were cultivatedin vitro in protein-free medium, in which the only macromolecular substance was dextran or carbowax. Physico-chemical analysis of secretion products was not succesful, since under the given cultivation conditions the cells started to disintegrate from the outset and the medium contained nucleic acids as well as proteins. Some of these substances were present in particles of the size of different subcellular particles. After cultivation of spleen and lymph node cells, antibodies were detected by an agglutination test in media containing dextran and carbowax. When particles substantially larger than the antibody molecule were removed by ultracentrifugation, the agglutination antibody titre in the medium fell.