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排序方式: 共有288条查询结果,搜索用时 32 毫秒
81.
Stéphanie C. Schai-Braun Darius Weber Klaus Hackländer 《European Journal of Wildlife Research》2013,59(3):387-397
The number of European brown hares (Lepus europaeus) has been declining throughout much of Europe since the 1960s. Consequently, many studies have focused on analysing habitat selection of European hares in order to improve the suitability of the habitat for this species. Habitat preferences of European hares are known to be affected by hare density, but most studies have been conducted in agricultural areas where hare densities were medium to high. Finding habitat preferences at high densities is difficult as most available habitats are occupied. In addition, in agricultural areas, field size might influence the hares’ habitat selection because it affects the distribution and availability of certain habitat types. However, most studies relate to areas with large field sizes. In this study, we analysed the habitat preferences of European hares in spring and autumn during the activity period, in the early hours of the night, in an agricultural area with low hare density and small average field size using Chesson’s electivity index. Moreover, we focused on the question whether two different habitat classifications varying in their specificity might cause contradictory results regarding European hares’ habitat preferences. Our results show that in this agricultural area with low hare density, European hares avoided several habitat types which were preferred in other study areas with higher hare densities. Therefore, we assume that hare density has an influence on the species’ habitat selection. In contrast, the small average field size of our study area seemed not to have an effect on hare habitat preference. Furthermore, by pooling habitat types into broader groups, substantial information was lost in some categories. Hence, for some categories, e.g. grassland or agricultural crop land, more detail might be needed than for others, such as urban areas, when analysing hares’ habitat selection. In conclusion, our results imply that studies on habitat preferences have to be conducted in areas with low hare density to be able to gain knowledge on the species’ habitat requirement and hereinafter improve the suitability of the habitat for this species. 相似文献
82.
Darius Hapetta 《Biocatalysis and Biotransformation》2013,31(4):288-295
Submerged cultures of Pleurotus ostreatus, when supplemented with β-myrcene, produced perillene, a rare furanoid monoterpene with a unique flowery citrus-like flavour. The major volatile products of the conversion were identified from which a substantiated conversion pathway has been derived. The isomeric epoxides 1,2- and 3,10-epoxymyrcene were found among the first enzymatic oxidation products. An unusual opening of both oxirane rings to the E/Z isomers of α-acaridiol was thought to be key to the fungal formation of perillene. Further oxidation of α-(Z)-acaridiol via the corresponding hydroxyaldehydes and lactols resulted in perillene formation. A new natural compound, 3-(4-methyl-3-pentenyl)-2,5-dihydrofuran-2-ol (α,α-acarilactol), was among the transformation products. 相似文献
83.
Sini Kerminen Nicola Cerioli Darius Pacauskas Aki S. Havulinna Markus Perola Pekka Jousilahti Veikko Salomaa Mark J. Daly Rupesh Vyas Samuli Ripatti Matti Pirinen 《PLoS genetics》2021,17(3)
Information about individual-level genetic ancestry is central to population genetics, forensics and genomic medicine. So far, studies have typically considered genetic ancestry on a broad continental level, and there is much less understanding of how more detailed genetic ancestry profiles can be generated and how accurate and reliable they are. Here, we assess these questions by developing a framework for individual-level ancestry estimation within a single European country, Finland, and we apply the framework to track changes in the fine-scale genetic structure throughout the 20th century. We estimate the genetic ancestry for 18,463 individuals from the National FINRISK Study with respect to up to 10 genetically and geographically motivated Finnish reference groups and illustrate the annual changes in the fine-scale genetic structure over the decades from 1920s to 1980s for 12 geographic regions of Finland. We detected major changes after a sudden, internal migration related to World War II from the region of ceded Karelia to the other parts of the country as well as the effect of urbanization starting from the 1950s. We also show that while the level of genetic heterogeneity in general increases towards the present day, its rate of change has considerable differences between the regions. To our knowledge, this is the first study that estimates annual changes in the fine-scale ancestry profiles within a relatively homogeneous European country and demonstrates how such information captures a detailed spatial and temporal history of a population. We provide an interactive website for the general public to examine our results. 相似文献
84.
Rimgaudas Treinys Deivis Dementavičius Gintautas Mozgeris Saulis Skuja Saulius Rumbutis Darius Stončius 《European Journal of Wildlife Research》2011,57(6):1165-1174
The processes of competition and predation determine the degree to which species can coexist; the importance of competition
in particular has been emphasized at high trophic levels. Competition exclusion will occur when habitat overlap between sympatric
species is high. In this study, we investigated nesting habitat overlap between internationally protected diurnal tree-nesting
avian predators of central Europe, namely, White-tailed Eagle (Haliaeetus albicilla), Lesser Spotted Eagle (Aquila pomarina), Black Stork (Ciconia nigra), and Osprey (Pandion haliaetus). We found significantly different nesting habitats among the study species and suggest that this could be a consequence
of the resource-based segregation, but not a consequence of asymmetrical interspecific competition. The results also show
that habitat of the recovering populations of White-tailed Eagle overlapped with the habitat used by the Lesser Spotted Eagle,
Black Stork, and Osprey to varying extents with a niche overlap values being below the competition exclusion threshold. Nevertheless,
we suggest that competition by White-tailed Eagle at a population level may limit Osprey, though not Lesser Spotted Eagle
or Black Stork. 相似文献
85.
Aida Laurinaviciene Darius Dasevicius Valerijus Ostapenko Sonata Jarmalaite Juozas Lazutka Arvydas Laurinavicius 《Diagnostic pathology》2011,6(1):1-10
Because metaplastic carcinoma of the breast encompasses a great variety of histopathology, diagnostic challenges abound, especially within the realm of cytology. The authors compiled and studied an eight-case series comprised of metaplastic breast carcinomas and lesions initially suspicious cytologically for metaplastic carcinoma in order to assess the degree of cytologic-histologic correlation and to identify recurring problematic themes surrounding the cytology-based diagnosis of this neoplasm. The cytologic and histologic slides from eight cases suspicious for metaplastic breast carcinoma diagnosed by fine needle aspiration (FNA) were collected and analyzed through a seven-year retrospective search of case files at our institution. Based on cytologic characteristics, the cases were separated into three groups. Group 1 consisted of three cases presenting with poorly differentiated adenocarcinoma and squamoid components on FNA. Group 2 was composed of two cases that featured a monophasic, malignant ductal cell population on cytology, while the cytologic specimens for the third group of cases presented with a mesenchymal component with or without a malignant glandular constituent. Cytologic-histologic correlation was present in two of three cases demonstrating a mesenchymal component, and there was 100% sensitivity in the cytologic detection of those mesenchymal elements. However, in only one of three cases was there an accurate cytologic diagnosis of metaplastic carcinoma when squamoid changes were present on FNA. Both cases demonstrating only malignant glandular elements on cytologic specimens revealed an additional component of malignant squamous differentiation upon the examination of mastectomy-derived tissue. These results indicate that squamous-like changes identified on FNA should be interpreted with caution and that sampling error remains a problematic recurrence in cytology. Regardless, there appears to be promise concerning the accurate cytologic diagnosis of metaplastic carcinoma when the lesion is characterized by a mesenchymal component. A study implementing a larger case number is essential in determining the significance of these findings. 相似文献
86.
Fabio Andres Castillo Martinez Eduardo Marcos Balciunas Attilio Converti Paul D. Cotter Ricardo Pinheiro de Souza Oliveira 《Biotechnology advances》2013
Bacteriocins are ribosomally-synthesized antibacterial peptides. These compounds are produced by a broad variety of different bacteria belonging mainly to the genus Bifidobacterium, to which health promoting properties have frequently been attributed. However, despite the fact that the identification of Bifidobacterium-associated bacteriocins was first reported in 1980 and that they exhibit antimicrobial activity against pathogenic microorganisms such as Listeria monocytogenes, Clostridium perfringens, and Escherichia coli, relatively little information is still available about the antimicrobial compounds produced by strains of this genus. More detailed understanding of the action mechanisms of these antimicrobials could allow us to determine the extent to which their production contributes to the probiotic properties of specific bifidobacteria strains and, potentially, be of crucial significance for ultimate preservation of functional foods or pharmaceutical applications. Here we review what is already known about their structure, classification, mode of action, functionality, immunity, production and purification. 相似文献
87.
Alexander L. Ruchelman Hon-Wah Man Weihong Zhang Roger Chen Lori Capone Jian Kang Anastasia Parton Laura Corral Peter H. Schafer Darius Babusis Mehran F. Moghaddam Yang Tang Michael A. Shirley George W. Muller 《Bioorganic & medicinal chemistry letters》2013,23(1):360-365
A series of analogs of the immunomodulary drugs lenalidomide (1) and pomalidomide (2), in which the amino group is replaced with various isosteres, was prepared and assayed for immunomodulatory activity and activity against cancer cell lines. The 4-methyl and 4-chloro analogs 4 and 15, respectively, displayed potent inhibition of tumor necrosis factor-α (TNF-α) in LPS-stimulated hPBMC, potent stimulation of IL-2 in a human T cell co-stimulation assay, and anti-proliferative activity against the Namalwa lymphoma cell line. Both of these analogs displayed oral bioavailability in rat. 相似文献
88.
Jay P. Parrish Sharon K. Lee Constantine G. Boojamra Hon Hui Darius Babusis Brandon Brown I-hung Shih Joy Y. Feng Adrian S. Ray Richard L. Mackman 《Bioorganic & medicinal chemistry letters》2013,23(11):3354-3357
Ribonucleoside phosphonate analogues containing 2′-α-fluoro modifications were synthesized and their potency evaluated against HCV RNA polymerase. The diphosphophosphonate (triphosphate equivalent) adenine and cytidine analogues displayed potent inhibition of the HCV polymerase in the range of 1.9–2.1 μM, but only modest cell-based activity in the HCV replicon. Pro-drugs of the parent nucleoside phosphonates improved the cell-based activity. 相似文献
89.
Singarapu KK Tonelli M Chow DC Frederick RO Westler WM Markley JL 《The Journal of biological chemistry》2011,286(50):43447-43453
Hsp12 (heat shock protein 12) belongs to the small heat shock protein family, partially characterized as a stress response, stationary phase entry, late embryonic abundant-like protein located at the plasma membrane to protect membrane from desiccation. Here, we report the structural characterization of Hsp12 by NMR and biophysical techniques. The protein was labeled uniformly with nitrogen-15 and carbon-13 so that its conformation could be determined in detail both in aqueous solution and in two membrane-mimetic environments, SDS and dodecylphosphocholine (DPC) micelles. Secondary structural elements determined from assigned chemical shifts indicated that Hsp12 is dynamically disordered in aqueous solution, whereas it gains four helical stretches in the presence of SDS micelles and a single helix in presence of DPC. These conclusions were reinforced by circular dichroism spectra of the protein in all three environments. The lack of long range interactions in NOESY spectra indicated that the helices present in SDS micelles do not pack together. R(1) and R(2), relaxation and heteronuclear NOE measurements showed that the protein is disordered in aqueous solution but becomes more ordered in presence of detergent micelles. NMR spectra collected in presence of paramagnetic spin relaxation agents (5DSA, 16DSA, and Gd(DTPA-BMA)) indicated that the amphipathic α-helices of Hsp12 in SDS micelles lie on the membrane surface. These observations are in agreement with studies suggesting that Hsp12 functions to protect the membrane from desiccation. 相似文献
90.
H. Taiana Darius Paul M. V. Martin Patrick A. D. Grimont and Catherine Dauga 《Journal of phycology》2000,36(5):951-959
The diversity of symbiotic dinoflagellates from reef-building corals collected in the lagoon of Tahiti (South Pacific ocean) was investigated by using a molecular approach. Populations of symbionts (strains or species) of 7 coral species ( Fungia scutaria , F. paumotensis Stutchbury, Pavona cactus Forskål, Leptastrea transversa Kluzinger, Pocillopora verrucosa Ellis and Solender, Montastrea curta Dana, and Acropora formosa Dana) were delimited by phylogenetic analysis of small subunit rDNA sequences. Coral P. verrucosa harbored 2 populations of symbiont SSU rDNA sequences that may correspond to two different Symbiodinium species. Corals F. scutaria and M. curta also seemed to contain two different Symbiodinium species. SSU rDNA dinoflagellate sequences from P. cactus , L. transversa , F. scutaria , F. paumotensis , and P. verrucosa were in the same phylogenetic cluster and showed low variability. For these distantly related coral species, dinoflagellate strains from the same species, rDNA paralogues from the same strain, or closely related Symbiodinium species could not be distinguished because monophyletic subgroups were not observed. SSU rDNA dinoflagellate sequences from A. formosa and M. curta were clearly different from the other Symbiodinium sequences and may represent specific species. This molecular approach highlighted a greater diversity of symbiotic dinoflagellates from corals in South Pacific ( Symbiodinium groups A, B, and C) than that observed in the rest of the Pacific ocean ( Symbiodinium group C). The diversity of symbiotic associations in a restricted area of the lagoon of Tahiti may reflect the complexity of interactions between species of Symbiodinium and corals. 相似文献