A unique enzyme of acetic acid bacteria, PQQ-dependent alcohol dehydrogenase, is also present in Frateuria aurantia

A membrane-bound, pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) was purified from Frateuria aurantia LMG 1558^T. Although F. aurantia belongs to a group of γ-Proteobacteria, the characteristics of its PQQ-ADH were similar to the enzyme characteristics of the typical high-acetic acid-resistant bacterium Gluconacetobacter europaeus from the group of α-Proteobacteria. The PQQ-dependent ADH was solubilized from the membranes and purified after anionic, cationic, and affinity chromatography with specific activity of 117 U/mg. The purified enzyme was estimated to be composed of two subunits of ca. 72 and 45 kDa, as judged by SDS-polyacrylamide gel electrophoresis. The purified enzyme had maximum activity at pH 4.5 and showed the highest substrate specificity to ethanol, isoamyl alcohol, 1-butanol, and 1-propanol. The deduced sequences of cloned genes adhA and adhB encoding subunits I and II of PQQ-ADH showed 80 % amino acid (AA) identity to AdhA and 68 % AA identity to AdhB of Ga. europaeus V3 (LMG 18494). Because of the high similarity between genes encoding subunits I and II of PQQ-ADH and its homologous genes found in a distantly related taxonomic group of acetic acid bacteria, the results suggest the possibility of horizontal gene transfer between these two groups of genera.     

Highly enantioselective oxidation of phenyl methyl sulfide and its derivatives into optically pure (S)-sulfoxides with Rhodococcus sp. CCZU10-1 in an n-octane–water biphasic system

Enantiopure sulfoxides can be prepared via the asymmetric oxidation of sulfides using sulfide monooxygenases. The n-octane–water biphasic system was chosen for the bio-oxidation of a water-insoluble phenyl methyl sulfide (PMS) by Rhodococcus sp. CCZU10-1. In this n-octane–water system, the optimum reaction conditions were obtained. (S)-phenyl methyl sulfoxide ((S)-PMSO) with >99.9 % enantiomeric excess formed at 55.3 mM in the n-octane–water biphasic system. Using fed-batch method, a total of 118 mM (S)-PMSO accumulated in 1-L reaction mixture after the 7th feed, and no (R)-PMSO and sulfone were detected. Moreover, Rhodococcus sp. CCZU10-1 displayed fairly good activity and enantioselectivity toward other sulfides. In conclusion, Rhodococcus sp. CCZU10-1 is a promising biocatalyst for synthesizing highly optically active sulfoxides.     

Sex steroid changes during temperature‐induced gonadal differentiation in Paralichthys olivaceus (Temminck & Schegel, 1846)

Sex steroid changes during temperature‐induced gonadal differentiation were evaluated in the olive flounder, Paralichthys olivaceus. Larvae were reared at 21 ± 0.5°C, 24 ± 0.5°C and 28 ± 0.5°C from day 40 post‐hatching (dph) to 90 dph. The proportion of males was 61.1, 76.7, 87.8 and 47.8% in 21°C, 24°C, 28°C and in control groups, respectively. Gonadal differentiation was circa 65 dph, when fishes were a mean 39 mm total length (TL). The gonads developed faster when fishes were reared in higher temperatures. Radioimmunoassay (RIA) analyses indicated that the level of estradiol‐17β (E2) changed during the period of gonadal differentiation and peaked at an onset of ovarian differentiation in all groups. Compared with fish in control groups, the levels of E2 were lower in thermal‐treated groups, especially in the highest temperature groups. The present results indicate that E2 plays a major role in the process of ovarian differentiation, and suggest that temperature‐induced masculinization in P. olivaceus is mainly due to a decrease in the E2 level during the period of ovarian differentiation.     

Length‐weight relationships of flatfish species caught by bottom trawl in the Yellow Sea and the Bohai Sea,China

This study determined the length–weight relationships of five flatfish species from the Yellow Sea and the Bohai Sea in China. Two of the species (Cynoglossus semilaevis and Verasper variegatus) had no previous length‐weight estimates.     

Production of phenolics and the emission of volatile organic compounds by perennial ryegrass (Lolium perenne L.)/Neotyphodium lolii association as a response to infection by Fusarium poae

Grasses very often form symbiotic associations with Neotyphodium/Epichloë endophytic fungi. These endophytes often allow the host grass to be protected from different pathogens. However, there is little known about the mechanisms of such endophyte influence on the host. Thus, the purpose of this research was to examine the effect of the N. lolii endophyte on the total production of phenolic compounds, VOCs emission and the resistance of three perennial ryegrass genotypes infected by pathogenic Fusarium poae. Analyses of total phenolics content were performed in control (not inoculated) and inoculated plants after 1, 2, 3, 4, 5, and 6 days (DAI) and for VOCs after 0, 3, 6 and 12 DAI. The presence of endophytes significantly reduced the disease index in two of the three genotypes relative to that in E−. Plants infected by N. lolii exhibited higher production of phenolics relative to the E− plants. The highest amounts of phenolics were observed on the second and sixth DAI. Genotype Nl22 showed the strongest effect of the endophyte on the production of phenolics, which increased by over 61%. Both the endophyte infected and non-infected plants emitted most abundantly two GLVs ((Z)-3-hexenal, (Z)-3-hexen-1-yl acetate), three terpenes (linalool, (Z)-ocimene, β-caryophyllene) and three shikimic acid pathway derivatives (benzyl acetate, indole, and methyl salicylate). The endophyte presence and the intervals of VOCs detection were a highly significant source of variation for all emitted volatiles (P < 0.001). The genotype of the perennial ryegrass significantly affected only the emission of methyl salicylate (P < 0.05) and β-caryophyllene (P < 0.05). Most of the VOCs ((Z)-3-hexen-1-yl acetate, (Z)-3-hexenal, linalool and methyl salicylate) reached their highest levels of emission on the sixth DAI, when averaged over genotypes and endophyte status. The results highlight the role of Neotyphodium spp. in the mediation of quadro-trophic interactions among plants, symbiotic endophytes, invertebrate herbivores and plant pathogenic fungi. Our results also confirm the fact that symbiotic plants can activate a defense reaction faster than non-symbiotic plants after a pathogen attack. Thus, N. lolii can be involved in the defense of perennial ryegrass against pathogens and potentially could be central to the host plants’ protection.     

Nickel-induced changes in carbon metabolism in wheat shoots

In this study, we analyzed the toxic effect of Ni during the development of wheat shoots. Typical developmental alterations in carbon metabolism-related parameters reflecting changes associated with the transition of the seedlings from heterotrophic to autotrophic metabolism were observed in the control shoots between the 1st and the 4th days. Adverse effects of 50 and 100 μM Ni became evident starting from the 4th day of growth on the metal-containing media. We found that Ni-induced stimulation of phosphoenolpyruvate carboxylase (PEPC) activity coincided with decrease in the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) level and with declines in net photosynthetic rate (P_N) and stomatal conductance (g_s). Application of Ni resulted in increased activities of several dehydrogenases: glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), isocitrate dehydrogenase (NADP-ICDH) and malate dehydrogenase (NADH-MDH). In contrast, the activities of malic enzymes (NADP-ME and NAD-ME) decreased due to Ni stress. Treatment with Ni led to accumulation of glucose and declined concentration of sucrose as well as considerable increases in concentrations of malic and citric acids. Our results indicate that Ni stress redirects the carbon metabolism of developing wheat shoots to provide carbon skeletons for synthesis of amino acids and organic acids as well as to supply reducing power to sustain normal metabolic processes and to support defense mechanisms against oxidative stress.     

Behavioural Responses of European Roe Deer to Temporal Variation in Predation Risk

In natural environments, predation risk varies over time. The risk allocation hypothesis predicts that prey is expected to adjust key anti‐predator behaviours such as vigilance to temporal variation in risk. We tested the predictions of the risk allocation hypothesis in a natural environment where both a species‐rich natural predator community and human hunters are abundant and where the differences in seasonal and circadian activity between natural and anthropogenic predators provided a unique opportunity to quantify the contributions of different predator classes to anti‐predator behaviour. Whereas natural predators were expected to show similar levels of activity throughout the seasons, hunter activity was high during the daytime during a clearly defined hunting season. According to the risk allocation hypothesis, vigilance should then be higher during the hunting season and during daytime hours than during the non‐hunting season and night‐time hours. Roe deer (Capreolus capreolus) on the edge of Bia?owie?a Primeval Forest in Eastern Poland displayed vigilance behaviour consistent with these predictions. The behavioural response of roe deer to temporarily varying predation risks emphasises the behavioural plasticity of this species and suggests that future studies of anti‐predator behaviour need to incorporate circadian variation in predation pressure as well as risk gradients of both natural and anthropogenic predators.     

Protective effects of EphB2 on Aβ1–42 oligomer-induced neurotoxicity and synaptic NMDA receptor signaling in hippocampal neurons

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized pathologically by the abnormal deposition of extracellular amyloid-β (Aβ) oligomers. However, the nature and precise mechanism of the toxicity of Aβ oligomers are not clearly understood. Aβ oligomers have been previously shown to cause a major loss of EphB2, a member of the EphB family of receptor tyrosine kinases. To determine the effect of EphB2 on Aβ oligomer-induced neurotoxicity and the underlying molecular mechanisms, we examined the EphB2 gene in cultured hippocampal neurons. Using a cellular model of AD, Aβ_1–42 oligomers were confirmed to induce neurotoxicity in a time-dependent manner and result in a major decrease of EphB2. EphB2 overexpression could prevent the neurotoxicity of hippocampal neurons from exposure to Aβ_1–42 oligomers for 1 h. Further analysis revealed that EphB2 overexpression increased synaptic NR1 and NR2B expression in Aβ_1–42 oligomer-treated neurons. Moreover, EphB2 overexpression prevented Aβ_1–42 oligomer-induced downregulation of dephosphorylated p38 MAPK and phosphorylated CREB. Together, these results suggest that EphB2 is a factor which protects hippocampal neurons against the toxicity of Aβ_1–42 oligomers, and we infer that the protection of EphB2 is achieved by increasing the synaptic NMDA receptor level and downstream p38 MAPK and CREB signaling in hippocampal neurons. This study provides new molecular insights into the neuroprotective effect of EphB2 and highlights its potential therapeutic role in the management of AD.     

Structural heterogeneity of linear habitats positively affects Barred Warbler Sylvia nisoria,Common Whitethroat Sylvia communis and Lesser Whitethroat Sylvia curruca in farmland of Western Poland

Capsule Structural heterogeneity was the most important factor influencing the distribution of Barred Warbler Sylvia nisoria, Common Whitethroat S. communis and Lesser Whitethroat S. curruca in linear habitats in farmland of Western Poland.

Aims To investigate the occurrence of three species of Sylvia warblers in relation to the spatial structure of linear habitats in the agricultural landscape of Western Poland where, in contrast to Western Europe, field boundaries are not managed in terms of their size or spatial structure.

Methods In 2008, the distribution of breeding territories of Sylvia warblers in linear habitats was estimated in farmland of Western Poland. Redundancy detrended analysis was used to assess the relationship between bird abundance and seven linear habitat variables in ninety-four 150?m sections.

Results Sylvia warblers differed in habitat requirements, however heterogeneity affected their distribution to the greatest extent. In addition, Barred Warbler preferred high shrub volume and wider sections, whereas Common Whitethroat was attracted by brambles and nettles and Lesser Whitethroat favoured shrubs. All species avoided a high proportion of low vegetation.

Conclusion Structural heterogeneity resulted in highly preferred linear habitats for Sylvia warblers. Thus, maintaining or increasing structural heterogeneity of linear habitats may be a very effective tool for the conservation of farmland bird populations.     

Predictive mapping of Meadow Pipit density using integrated remote sensing data and an atlas of vascular plants dataset

Capsule The highest densities of Meadow Pipits in Central Europe are found in lowland and upland wet meadows.

Aims To create a large-scale predictive model of Meadow Pipit density.

Methods We analysed factors affecting the density of the Meadows Pipit in Poland using data from 777?×?1?km study plots and a set of 22 environmental variables, including agriculture intensification and habitat-specific plant species as classifiers of meadow types. Predictors were selected using variation inflation factor, then related to species density data using generalized additive models.

Results The best-supported model included 11 variables and was clearly better (Akaike information criterion weight?=?0.47) than other models. The density of the Meadow Pipit reaches its highest levels on large areas of extensively used wet meadows as well as pastures where livestock graze and which show high photosynthetic activity in April.

Conclusion Some aspects of the environment that were not identified from remote sensing data were vital for determining relatively high density. Conservation efforts for preserving Meadow Pipit populations should focus on maintaining wet meadows and extensively grazed pastures. Given the results, the Meadows Pipit may be classified as a good indicator of traditional agriculture.