Five disulfide bridges stabilize a hevein-type antimicrobial peptide from the bark of spindle tree (Euonymus europaeus L.)

A small 45 amino acid residue antifungal polypeptide was isolated from the bark of spindle tree (Euonymus europaeus L.). Though the primary structure of this so-called E. europaeus chitin-binding protein or Ee-CBP is highly similar to the hevein domain, it distinguishes itself from most previously identified hevein-type antimicrobial peptides (AMP) by the presence of two extra cysteine residues that form an extra disulfide bond. Due to these five disulfide bonds Ee-CBP is a remarkably stable protein. Agar diffusion and microtiterplate assays demonstrated that Ee-CBP is a potent antimicrobial protein. IC₅₀-values as low as 1 μg/ml were observed for the fungus Botrytis cinerea. Comparative assays further demonstrated that Ee-CBP is a stronger inhibitor of fungal growth than Ac-AMP2 from Amaranthus caudatus seeds, which is considered one of the most potent antifungal hevein-type plant proteins.     

Factors affecting the abundance of introduced hedgehogs (Erinaceus europaeus) to the Hebridean island of South Uist in the absence of natural predators and implications for nesting birds

Introduced hedgehogs Erinaceus europaeus are a known threat to ground-nesting birds on many islands. Spring hedgehog density and sex ratio were measured over a 5-year period at four plots on the 315 km² Hebridean island of South Uist. The mean instantaneous density on the sandy-soiled machair plots (31.8 hedgehogs km⁻², se 2.95) was over twice that on the peaty-soiled blackland plots (15.4 hedgehogs km⁻², se 3.46), a difference reflecting the amount of preferred foraging habitat (mainly pasture). Plot population densities fluctuated approximately in unison. Year-to-year density changes were strongly correlated with temperature in the preceding winter and previous year's spring/summer, indicating that warmer conditions promote both survival and breeding success. The mean spring sex ratio of sub-adults (animals born in the previous calendar year) was not significantly different from 1M:1F. However, the 1.8M:1F ratio observed for adults was significantly male biased, probably a result of female mortality associated with rearing young. The study estimates that in an average year the South Uist hedgehog population numbers c . 2750 (95% confidence limit±800) adults and sub-adults and these produce around 3000 young. Compared with the native range, hedgehog densities on South Uist are shown to be unusually high, probably because their natural predators are absent. High hedgehog densities have led directly to high rates of egg predation of ground-nesting shorebirds and subsequent declines in bird populations. The results suggest that over the past 20 years egg losses have become more severe and control of hedgehogs more difficult because climate warming has resulted in generally more favourable conditions for hedgehogs on the islands.     

Better safe than sorry: The response to a simulated predator and unfamiliar scent by the European hare

Predator presence can create a “landscape of fear,” which is defined as the spatially explicit distribution of perceived predation risk as seen by prey. Prey species can alter their behavior and space use as a response to increased predation risk, which might be traded off with energetic requirements. Thus, whether or not an anti-predator behavior is performed might depend on the perceived risk. In this study, we investigated the behavioral and spatial response of the European hare (Lepus europaeus) toward the presence of a predator scent, using red fox (Vulpes vulpes) scat, an unfamiliar control scent (butyric acid), and a true control (no scent). We collected data on hare activity times and behavior using 50 camera trap locations and spatial data using GPS telemetry (30,481 GPS positions of 12 hares). Hares showed spatial anti-predator behaviors within their home range, for example, the local avoidance of areas treated with scent and remaining further from field edges, in response to sympatric predator scent and partly also in response to unfamiliar butyric acid. Conversely, more costly anti-predator behaviors, that is, increased vigilance at the expense of foraging, were only shown in response to the predator scent. Our results suggest that prey species respond flexibly toward scent cues, utilizing less costly anti-predator behaviors independent of the perceived threat, whereas costly anti-predator responses are only used in the presence of “real” threat. Further, our findings emphasize that a combination of camera trap and GPS data can provide detailed information on animal behavior and space use, and caution that interpretation of one data source alone might lead to incomplete conclusions.     

Studies on Galalpha3-binding proteins: comparison of the glycosphingolipid binding specificities of Marasmius oreades lectin and Euonymus europaeus lectin

The carbohydrate binding preferences of the Galalpha3Galbeta4 GlcNAc-binding lectins from Marasmius oreades and Euonymus europaeus were examined by binding to glycosphingolipids on thin-layer chromatograms and in microtiter wells. The M. oreades lectin bound to Galalpha3-terminated glycosphingolipids with a preference for type 2 chains. The B6 type 2 glycosphingolipid (Galalpha3[Fucalpha2]Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer) was preferred over the B5 glycosphingolipid (Galalpha3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer), suggesting that the alpha2-linked Fuc is accommodated in the carbohydrate binding site, providing additional interactions. The lectin from E. europaeus had broader binding specificity. The B6 type 2 glycosphingolipid was the best ligand also for this lectin, but binding to the B6 type 1 glycosphingolipid (Galalpha3[Fucalpha2]Galbeta3GlcNAcbeta3Galbeta4Glcbeta1Cer) was also obtained. Furthermore, the H5 type 2 glycosphingolipid (Fucalpha2Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer), devoid of a terminal alpha3-linked Gal, was preferred over the the B5 glycosphingolipid, demonstrating a significant contribution to the binding affinity by the alpha2-linked Fuc. The more tolerant nature of the lectin from E. europaeus was also demonstrated by the binding of this lectin, but not the M. oreades lectin, to the x2 glycosphingolipid (GalNAcbeta3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer) and GlcNAcbeta3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer. The A6 type 2 glycosphingolipid (GalNAcalpha3[Fucalpha2]Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer) and GalNAcalpha3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1-Cer were not recognized by the lectins despite the interaction with B6 type 2 glycosphingolipid and the B5 glycosphingolipid. These observations are explained by the absolute requirement of a free hydroxyl in the 2-position of Galalpha3 and that the E. europaea lectin can accommodate a GlcNAc acetamido moiety close to this position by reorienting the terminal sugar, whereas the M. oreades lectin cannot.     

Seasonal Changes in Microhabitat Use and Niche Overlap between Akodon azarae and Calomys laucha (Rodentia,Muridae) in Agroecosystems of Central Argentina

We examined seasonal changes in microhabitat use by the murid rodents Akodon azarae and Calomys laucha in agroecosystems of the former pampa region of Argentina. In summer, trap data showed that both species had low densities and were almost equally distributed between the mature cropfields and their surrounding weedy borders. Analysis of vegetation at the trap sites revealed no selection for microhabitats at the borders, whereas in the cropfields both species shared preferences for covered microhabitats. In contrast, winter data revealed a sharp habitat segregation, being Calomys numerically dominant in post-harvest cropfields and Akodon more abundant in borders. Moreover, there were clear differences in microhabitat selection at the borders, A. azarae occupying the more covered microhabitats and C. laucha the less covered. Breadth and overlap of niches were calculated using principal component analysis, in order to recognize interspecific competition and its influence on community niche space. Available evidence indicates that the structure of this rodent community is strongly influenced by seasonal changes in habitat stucture and rodent abundance. The socially dominant A. azarae retains the best part of the available niche space, a fact becoming more evident under the harsh winter conditions.     

Notes on New Zealand mammals 10. Effect of observer position on group size and level of aggression of mating brown hares

Abstract

The sex pheromones of two endemic New Zealand tortricid species were investigated. Females of the first species, Cnephasia jactatana, a pest of kiwifruit, were found to produce (Z)-11-tetradecenyl acetate (Z11-14:OAc) in their sex pheromone gland. When tested in the field, this compound on its own elicited significant catches of male C. jactatana. However, the addition of even very small amounts (0.3%) of the geometric isomer, (E)-11-tetradecenyl acetate (E11-14:OAc), to Z 11-14:OAc virtually suppressed trap catches. The sex pheromone of the second species, Merophyas leucaniana, was found to consist of a mixture of Z11-14:OAc, E11-14:OAc, tetradecyl acetate, and (Z)-11-tetradecenol. This species is morphologically very similar to the congeneric species, M. divulsana, the Australian lucerne leafroller. The sex pheromone of M. leucaniana is also very similar to that of the so-called “Z-type” of M. divulsana, which is now found in New Zealand. The pheromone components of C. jactatana and M. leucaniana are discussed in relation to those found in other tortricids.     

Habitat use of nightjar (Caprimulgus europaeus) in an Austrian pine forest

The Steinfeld in Lower Austria supports a population of European Nightjar (Caprimulgus europaeus) which was extensively studied during 1997 and 1998. The study area encompassed a pine forest of 20 km². The population densities of 1.05 and 1.25 territories/km², respectively, lies within the range found in central European populations. Annual monitoring until 2001 has shown the population to be stable. To gain an insight into habitat use of the species, various habitat-related parameters were measured inside and outside the territories, namely structure of trees, density of trees, structure of undergrowth vegetation and structure of clearings. Discriminant analysis was applied to assess the factors responsible for habitat choice of the Nightjar population. The findings showed that the Nightjars territories were frequently centered on a large clearing with an area of at least 0.7 ha. Clearings less than 50 m wide were not colonized. The requirement for a minimum width of a clearing in addition to a minimum area probably relates to better hunting conditions. Nightjars prefer trees where the lower edge of the crown is on average 4.38 m higher than at control points so that males can churr from dead branches immediately below the canopy. Such trees were found on the edge of clearings in the forest, and the edge of a clearing thus had a pronounced effect on the quality of a territory. In contrast to reports in the literature, neither the proportion of bare patches of ground nor the average height of undergrowth vegetation was found to be decisive for territory selection.     

冬眠与非冬眠刺猬小肠运动机能与对Ad、Ach反应敏感性比较

对47只冬眠季冬眠阵低温期刺猬的小肠与53只非冬眠季刺猬的小肠,在11.5℃和37℃及离体条件下的收缩强度进行比较,和在37℃条件下对肾上腺素（Ad）、乙酰胆硷（Ach）、心得安（Propranolol）、阿托品（Atr）反应进行比较,表明在11.5℃条件下,冬眠与非冬眠刺猬离体小肠都基本无运动机能,在37℃条件下,冬眠季冬眠阵低温期刺猬离体小肠运动强度明显高于非冬眠季、Ad、Ach、Propranolol、Atr使冬眠季冬眠阵低温期刺猬离体小肠收缩强度变化率明显高于非冬眠季。