Screening of microbes for novel acidic cutinases and cloning and expression of an acidic cutinase from Aspergillus niger CBS 513.88

Isolates from gardening waste compost and 38 culture collection microbes were grown on agar plates at pH 4.0 with the cutinase model substrate polycaprolactone as a carbon source. The strains showing polycaprolactone hydrolysis were cultivated in liquid at acidic pH and the cultivations were monitored by assaying the p-nitrophenyl butyrate esterase activities. Culture supernatants of four strains were analyzed for the hydrolysis of tritiated apple cutin at different pHs. Highest amounts of radioactive hydrolysis products were detected at pHs below 5. The hydrolysis of apple cutin by the culture supernatants at acidic pH was further confirmed by GC–MS analysis of the hydrolysis products. On the basis of screening, the acidic cutinase from Aspergillus niger CBS 513.88 was chosen for heterogeneous production in Pichia pastoris and for analysis of the effects of pH on activity and stability. The recombinant enzyme showed activity over a broad range of pHs with maximal activity between pH 5.0 and 6.5. Activity could be detected still at pH 3.5.     

Effects of Auditory Attention Training with the Dichotic Listening Task: Behavioural and Neurophysiological Evidence

Facilitation of general cognitive capacities such as executive functions through training has stirred considerable research interest during the last decade. Recently we demonstrated that training of auditory attention with forced attention dichotic listening not only facilitated that performance but also generalized to an untrained attentional task. In the present study, 13 participants underwent a 4-week dichotic listening training programme with instructions to report syllables presented to the left ear (FL training group). Another group (n = 13) was trained using the non-forced instruction, asked to report whichever syllable they heard the best (NF training group). The study aimed to replicate our previous behavioural results, and to explore the neurophysiological correlates of training through event-related brain potentials (ERPs). We partially replicated our previous behavioural training effects, as the FL training group tended to show more allocation of auditory spatial attention to the left ear in a standard dichotic listening task. ERP measures showed diminished N1 and enhanced P2 responses to dichotic stimuli after training in both groups, interpreted as improvement in early perceptual processing of the stimuli. Additionally, enhanced anterior N2 amplitudes were found after training, with relatively larger changes in the FL training group in the forced-left condition, suggesting improved top-down control on the trained task. These results show that top-down cognitive training can modulate the left-right allocation of auditory spatial attention, accompanied by a change in an evoked brain potential related to cognitive control.     

Determination (by methylation analysis) of the substitution pattern of 2-amino-2-deoxyhexitols obtained from O-glycosylic carbohydrate units of glycoproteins

The derivatives obtained by per-methylation of unsubstituted 2-amino-2-deoxy-hexitols and of these compounds monosubstituted at C-3. C-4, or C-6, and disubstituted at C-3 and C-6, have been analysed by g.l.c.-m.s. Each derivative can be identified on the basis of retention time and mass spectrum. In methylation analysis, methanolysis gave one derivative of each hexitol, whereas a mixture of products was formed when degradation was effected by acetolysis followed by hydrolysis. An application in the analysis of amino-sugar linkages in alkali-labile O-glycosylic oligosaccharides from rat-brain glycoproteins is described.     

A single bout of exercise with high mechanical loading induces the expression of Cyr61/CCN1 and CTGF/CCN2 in human skeletal muscle.

High mechanical loading was hypothesized to induce the expression of angiogenic and/or lymphangiogenic extracellular matrix (ECM) proteins in skeletal muscle. Eight men performed a strenuous exercise protocol, which consisted of 100 unilateral maximal drop jumps followed by submaximal jumping until exhaustion. Muscle biopsies were taken 30 min and 48 h postexercise from the vastus lateralis muscle and analyzed for the following parameters: mRNA and protein expression of ECM-associated CCN proteins [cysteine-rich angiogenic protein 61 (Cyr61)/CCN1, connective tissue growth factor (CTGF)/CCN2], and mRNA expression of vascular endothelial growth factors (VEGFs) and hypoxia-inducible factor-1alpha. The mRNA expression of Cyr61 and CTGF increased 30 min after the exercise (14- and 2.5-fold, respectively; P < 0.001). Cyr61 remained elevated 48 h postexercise (threefold; P < 0.05). The mRNA levels of VEGF-A, VEGF-B, VEGF-C, VEGF-D, or hypoxia-inducible factor-1alpha did not change significantly at either 30 min or 48 h postexercise; however, the variation between subjects increased markedly in VEGF-A and VEGF-B mRNA. Cyr61 protein levels were higher at both 30 min and 48 h after the exercise compared with the control (P < 0.05). Cyr61 and CTGF proteins were localized to muscle fibers and the surrounding ECM by immunohistochemistry. Fast fibers stained more intensively than slow fibers. In conclusion, mechanical loading induces rapid expression of CCN proteins in human skeletal muscle. This may be one of the early mechanisms involved in skeletal muscle remodeling after exercise, since Cyr61 and CTGF regulate the expression of genes involved in angiogenesis and ECM remodeling.     

Environmental correlates of annual survival differ between two ecologically similar and congeneric owls

Understanding how survival is affected by the environment is essential to gain insight into population dynamics and the evolution of life‐history traits as well as to identify environmental selection pressures. However, we still have little understanding of the relative effect of different environmental factors and their interactions on demographic traits and population dynamics. Here we used two long‐term, individual‐based datasets on Tawny Owl Strix aluco (1981–2010) and Ural Owl S. uralensis (1986–2010) to undertake capture‐mark‐recapture analysis of annual survival of adult females in response to three biologically meaningful environmental variables and their two‐way interactions. Despite the similar ecology of these two species, their survival was associated with different and uncorrelated environmental drivers. The main correlate of Tawny Owl survival was an inverse association with snow depth (winter severity). For Ural Owl, high food (vole) abundance improved survival during years with deep snow, but was less important during years with little snow. In addition, Ural Owl survival was strongly density‐dependent, whereas Tawny Owl survival was not. Our findings advise caution in extrapolating demographic inferences from one species to another, even when they are very closely related and ecologically similar. Analyses including only one or few potential environmental drivers of a species' survival may lead to incomplete conclusions because survival may be affected by several factors and their interactions.     

The effect of past changes in inter‐annual temperature variability on tree distribution limits

Aim The northern limits of temperate broadleaved species in Fennoscanndia are controlled by their requirements for summer warmth for successful regeneration and growth as well as by the detrimental effects of winter cold on plant tissue. However, occurrences of meteorological conditions with detrimental effects on individual species are rare events rather than a reflection of average conditions. We explore the effect of changes in inter‐annual temperature variability on the abundances of the tree species Tilia cordata, Quercus robur and Ulmus glabra near their distribution limits using a process‐based model of ecosystem dynamics. Location A site in central Sweden and a site in southern Finland were used as examples for the ecotone between boreal and temperate forests in Fennoscandia. The Finnish site was selected because of the availability of varve‐thickness data. Methods The dynamic vegetation model LPJ‐GUESS was run with four scenarios of inter‐annual temperature forcing for the last 10,000 years. In one scenario the variability in the thickness of summer and winter varves from the annually laminated lake in Finland was used as a proxy for past inter‐annual temperature variability. Two scenarios were devised to explore systematically the effect of stepwise changes in the variance and shape parameter of a probability distribution. All variability scenarios were run both with and without the long‐term trend in Holocene temperature change predicted by an atmospheric general circulation model. Results Directional changes in inter‐annual temperature variability have significant effects on simulated tree distribution limits through time. Variations in inter‐annual temperature variability alone are shown to alter vegetation composition by magnitudes similar to the magnitude of changes driven by variation in mean temperatures. Main conclusions The varve data indicate that inter‐annual climate variability has changed in the past. The model results show that past changes in species abundance can be explained by changes in the inter‐annual variability of climate parameters as well as by mean climate. Because inter‐annual climatic variability is predicted to change in the future, this component of climate change should be taken into account both when making projections of future plant distributions and when interpreting vegetation history.     

Larger temperature response of autumn leaf senescence than spring leaf‐out phenology

Climate warming is substantially shifting the leaf phenological events of plants, and thereby impacting on their individual fitness and also on the structure and functioning of ecosystems. Previous studies have largely focused on the climate impact on spring phenology, and to date the processes underlying leaf senescence and their associated environmental drivers remain poorly understood. In this study, experiments with temperature gradients imposed during the summer and autumn were conducted on saplings of European beech to explore the temperature responses of leaf senescence. An additional warming experiment during winter enabled us to assess the differences in temperature responses of spring leaf‐out and autumn leaf senescence. We found that warming significantly delayed the dates of leaf senescence both during summer and autumn warming, with similar temperature sensitivities (6–8 days delay per °C warming), suggesting that, in the absence of water and nutrient limitation, temperature may be a dominant factor controlling the leaf senescence in European beech. Interestingly, we found a significantly larger temperature response of autumn leaf senescence than of spring leaf‐out. This suggests a possible larger contribution of delays in autumn senescence, than of the advancement in spring leaf‐out, to extending the growing season under future warmer conditions.     

THE EVOLUTION OF HOST-PLANT USE AND SEQUESTRATION IN THE LEAF BEETLE GENUS PHRATORA (COLEOPTERA: CHRYSOMELIDAE)

Leaf beetles in the genus Phratora differ in host plant use and in the chemical composition of their larval defensive secretion. Most species specialize on either poplars or willows (family Salicaceae), but two species feed on birch (family Betulaceae). Phratora vitellinae utilizes salicylates from the host plant to produce its larval secretion, which contains salicylaldehyde, while other Phratora species produce an autogenous secretion. To reconstruct the evolutionary history of host plant use and the larval secretion chemistry in this genus, we sequenced 1383 base pairs of the mt cytochrome oxidase I gene for six European and one North American Phratora species and three outgroup taxa. Bootstrap values of the complete nucleotide sequence were 99-100% for six of eight nodes in the maximum parsimony tree. They were 71% and 77% for the two other nodes. The maximum parsimony tree and the maximum likelihood tree based on nucleotide sequence showed the same relationships as a maximum parsimony tree based on the amino acid sequence. Beetle phylogeny overlapped broadly with host plant taxonomy and chemistry, and it revealed historical constraints influencing host plant use. However, there was one host shift from the willow family (Salicaceae) to the birch family (Betulaceae). The use of host plant phenol glycosides for the larval defensive secretion evolved along the lineage that led to P. vitellinae. Phratora vitellinae feeds on the taxonomically widest range of host plants, which are characterized by moderate to high levels of salicylates. The results support the hypothesis that the use of salicylates for the larval secretion evolved twice independently in chrysomeline leaf beetles.