Present and historical landscape structure shapes current species richness in Central European grasslands     

Scherreiks  Pascal  Gossner  Martin M.  Ambarl&#;  Didem  Ayasse  Manfred  Bl&#;thgen  Nico  Fischer  Markus  Klaus  Valentin H.  Kleinebecker  Till  Neff  Felix  Prati  Daniel  Seibold  Sebastian  Simons  Nadja K.  Weisser  Wolfgang W.  Wells  Konstans  Westphal  Catrin  Thiele  Jan 《Landscape Ecology》2022,37(3):745-762

Landscape Ecology - Current diversity and species composition of ecological communities can often not exclusively be explained by present land use and landscape structure. Historical land use may...  相似文献   

Long-term management impacts on soil C, N and physical fertility: Part III: Tamworth crop rotation experiment     

Nelly Blair  R.D. Faulkner  A.R. Till  G.J. Crocker 《Soil & Tillage Research》2006,91(1-2):48-56

Degradation of soil structure can lead to increased risk of run-off and soil erosion, and therefore, it is necessary to implement management practices that are more sustainable and will enhance and rehabilitate soils while increasing food production. The impact of small-grain rotations grown with legumes, fallow and continuously on total C (C_T), labile C (C_L), non-labile C (C_NL), total N (N_T), aggregation expressed as mean weight diameter (MWD) and infiltration determined as unsaturated hydraulic conductivity (K_unsat) were examined in a long-term rotation trial established in 1966 on a Black Earth (Pellic Vertisol) and a Red Clay (Chromic Vertisol) soil near Tamworth, in New South Wales, Australia. The results were compared with an adjacent uncropped pasture on each soil type. Cropping reduced all C fractions, N_T, MWD and K_unsat on both soils, which were further degraded when long fallowing was included in the rotation. C_L decreased by 70% with long fallow in the Red Clay and by 78% in the Black Earth compared with the adjacent pasture, while MWD decreased by 61% in the Red Clay and 91% in the Black Earth. Rotation of cereals with legumes resulted in smaller decreases in C fractions, N_T, MWD and K_unsat when compared with pasture. Rotation with lucerne (Medicago sativa) resulted in 41% higher C_L, 45% higher MWD and 87% higher K_unsat (10 mm tension) than long fallow on the Red Clay soil and 65, 126 and 43% higher on the Black Earth soil. There were strong positive correlations of soil C fractions and N_T with MWD for both soil types. Similar significant relationships were found for all C fractions and N_T with K_unsat (10 mm tension) for the Red Clay soil, but not for the Black Earth. Rotations with forage legumes can limit declines in C fractions, N_T, MWD and K_unsat when cropping these soils and has potential to increase soil sustainability.  相似文献   

Soil faunal assemblage composition modifies root in-growth to plant litter patches     

Mark A. Bradford  Till Eggers  John E. Newington  George M. Tordoff 《Pedobiologia》2007,50(6):505-513

Local-scale heterogeneity in the spatial distribution of soil nutrients promotes a suite of physiological and morphological responses in plants. These responses influence the competitive ability of plants within communities and potentially plant primary productivity. There is a growing appreciation then for the need to study factors that may modulate these plant responses to soil nutrient heterogeneity. Soil fauna are potentially one such modulating factor. For example, through impacts on organic matter decomposition and distribution they may directly modify nutrient patches and therefore the stimulus plants are responding to. In addition they may modify plant root mass and architecture through processes such as herbivory, potentially altering the outcome of a plant's response to a nutrient patch. Using grassland microcosms, consisting of a multi-species plant assemblage, multiple soil horizons and a speciose soil biota, we tested whether soil faunal assemblage composition might modulate plant responses to nutrient patches represented by litterbags. We show that root proliferation into a nutrient patch, a variable which is positively related to a plant's success under conditions of interspecific competition in a nutrient-limited environment, is reduced by the presence of mesofauna, and even more so by the presence of mesofauna together with macrofauna. Reductions in this proliferation response when mesofauna were present without macrofauna appeared to be a function of reduced root density. When macrofauna were included, reduced root density, and higher rates of litter patch disappearance, together contributed to the reduction in proliferation but additional mechanisms must also have played a role. Our results suggest that the effects and interactions generated by soil fauna need to be explicitly considered in analyses of how plants forage for nutrients in a patchy environment.  相似文献   

Inhalational anesthetics stereochemistry: optical resolution of halothane, enflurane, and isoflurane.   总被引：4，自引：0，他引：4  

J Meinwald  W R Thompson  D L Pearson  W A K?nig  T Runge  W Francke 《Science (New York, N.Y.)》1991,251(4993):560-561

Halothane (I), enflurane (II), and isoflurane (III), which are among the most important inhalation anesthetics, are currently administered as racemic mixtures. The pure enantiomers have not been described, and no analytical method for resolving the commercially available racemic mixtures has been reported. Complete optical resolution of (+/-)-I and (+/-)-III on per-n-pentylated alpha-cyclodextrin (Lipodex A) and of (+/-)-II and (+/-)-III on octakis(6-O-methyl-2,3-di-O-pentyl)-gamma-cyclodextrin capillary columns has been achieved, making rapid and convenient determination of enantiomeric ratios in samples of all three of these anesthetics possible.  相似文献   

Global analysis of the protection status of the world’s forests     

Christine B. Schmitt  Neil D. Burgess  Lauren Coad  Alexander Belokurov  Charles Besanon  Lauriane Boisrobert  Alison Campbell  Lucy Fish  Derek Gliddon  Kate Humphries  Valerie Kapos  Colby Loucks  Igor Lysenko  Lera Miles  Craig Mills  Susan Minnemeyer  Till Pistorius  Corinna Ravilious  Marc Steininger  Georg Winkel 《Biological conservation》2009,142(10):2122-2130

This study presents a global analysis of forest cover and forest protection. An updated Global Forest Map (using MODIS2005) provided a current assessment of forest cover within 20 natural forest types. This map was overlaid onto WWF realms and ecoregions to gain additional biogeographic information on forest distribution. Using the 2008 World Database on Protected Areas, percentage forest cover protection was calculated globally, within forest types, realms and ecoregions, and within selected areas of global conservation importance. At the 10% tree cover threshold, global forest cover was 39 million km². Of this, 7.7% fell within protected areas under IUCN management categories I–IV. With the inclusion of IUCN categories V and VI, the level of global forest protection increased to 13.5%. Percentage forest protection (IUCN I–IV) varied greatly between realms from 5.5% (Palearctic) to 13.4% (Australasia), and for forest types from 3.2% (temperate freshwater swamp forest) to 28% (temperate broadleaf evergreen forest). Median protection of forest cover in 670 ecoregions (forest above a specified threshold) was 5.9% (IUCN I–IV); at IUCN I–VI, 46% of the ecoregions had less than 10% forest protection. Considering their biodiversity importance, forest protection within global priority areas was insufficient, e.g., median protection of 8.4% in biodiversity hotspots (IUCN I–IV). Results have policy relevance in terms of the target of the Convention on Biological Diversity (CBD), reconfirmed in 2008, to effectively conserve “at least 10% of each of the world’s forest types”. Regular updates of these analyses would allow progress towards achieving that target to be monitored.  相似文献   

Effect of povidone, povidone-iodine, and iodide on locomotion (in vitro) of neutrophils from people, rats, dogs, and rabbits     

H W Tvedten  G O Till 《American journal of veterinary research》1985,46(8):1797-1800

The effect of the antiseptic povidone-iodine (P-I) on neutrophil locomotion was tested in vitro. Neutrophil migration into Micropore filters was significantly stimulated by P-I at concentrations between 0.03% and 0.005%. At higher concentrations (greater than or equal to 0.05%), a dose-dependent inhibition of neutrophil migration could be observed which was due to cytotoxic effects of P-I as shown by pyknosis and cell lysis. To analyze these effects, 2 components of P-I (namely, povidone and iodide) were tested separately. In these tests, povidone induced a pronounced stimulation of neutrophil migration at concentrations similar to the stimulatory concentrations of P-I. Inhibition of neutrophil migration or cytotoxic effects of povidone was not observed, even when tested at high concentrations (5.0%). Iodide (as NaI or KI) was cytotoxic and strongly inhibited neutrophil migration when it was tested at concentrations greater than that likely to be present in the inhibitory concentrations of P-I. Stimulatory effects of iodide on neutrophil migration could not be observed when tested over a wide range of noncytotoxic concentrations. Free iodine was not tested, but was considered to be the toxic component by exclusion. The patterns of response were similar for neutrophils from the 4 species tested. Migration of rabbit neutrophils, however, was inconsistently and weakly stimulated by P-I or povidone. These data indicate that the widely used antiseptic P-I, depending on its concentration, can either stimulate or inhibit neutrophil migration.  相似文献   

Marine Indole Alkaloids     

Natalie Netz  Till Opatz 《Marine drugs》2015,13(8):4814-4914

Marine indole alkaloids comprise a large and steadily growing group of secondary metabolites. Their diverse biological activities make many compounds of this class attractive starting points for pharmaceutical development. Several marine-derived indoles were found to possess cytotoxic, antineoplastic, antibacterial and antimicrobial activities, in addition to the action on human enzymes and receptors. The newly isolated indole alkaloids of marine origin since the last comprehensive review in 2003 are reported, and biological aspects will be discussed.  相似文献   

Vaccine-induced antibodies linked to bovine neonatal pancytopenia (BNP) recognize cattle major histocompatibility complex class I (MHC I)     

Deutskens F  Lamp B  Riedel CM  Wentz E  Lochnit G  Doll K  Thiel HJ  Rümenapf T 《Veterinary research》2011,42(1):97

ABSTRACT: A mysterious disease affecting calves, named bovine neonatal pancytopenia (BNP), emerged in 2007 in several European countries. Epidemiological studies revealed a connection between BNP and vaccination with an inactivated vaccine against bovine virus diarrhea (BVD). Alloantibodies reacting with blood leukocytes of calves were detected in serum and colostrum of dams, which have given birth to calves affected by BNP. To understand the linkage between vaccination and the development of alloantibodies, we determined the antigens reacting with these alloantibodies. Immunoprecipitation of surface proteins from bovine leukocytes and kidney cells using sera from dams with a confirmed case of BNP in their gestation history reacted with two dominant protein species of 44 and 12 kDa. These proteins were not detected by sera from dams, free of BVDV and not vaccinated against BVD, and from sera of animals vaccinated with a different inactivated BVD vaccine. The 44 kDa protein was identified by mass spectrometry analysis as MHC I, the other as β-2-microglobulin. The presence of major histocompatibility complex class I (MHC I) in the vaccine was confirmed by Western blot using a MHC I specific monoclonal antibody. A model of BNP pathogenesis is proposed.  相似文献   

Capacity prediction of welded timber joints     

Till Vallée  Thomas Tannert  Christelle Ganne-Chedville 《Wood Science and Technology》2012,46(1-3):333-347

Linear vibration welding of timber structural elements provides new opportunities to potentially achieve structural joints. This paper investigates to which extent welded joints can be considered for load-bearing structural joints. On the basis of a series of experimental and numerical investigations on a series of welded single-lap joints, failure modes were identified, and the associated failure criterion was quantified. A probabilistic method subsequently allowed accurately predicting the capacity of the tested wood welded joints exclusively based on objective input data, including an estimate of the scattering due to the material’s inherent variability.  相似文献   

Disposable biosensor test for organophosphate and carbamate insecticides in milk   总被引：3，自引：0，他引：3  

Zhang Y  Muench SB  Schulze H  Perz R  Yang B  Schmid RD  Bachmann TT 《Journal of agricultural and food chemistry》2005,53(13):5110-5115

A highly sensitive and rapid biosensor test based on disposable screen-printed thick-film electrodes was developed, which is suitable for monitoring organophosphate and carbamate residues in foods of animal origin with increased fat contents such as milk. The wild-type enzyme was combined with three engineered variants of Nippostrongylus brasiliensis acetylcholinesterase (NbAChE), to obtain enhanced sensitivity. The sample pretreatment could be reduced to a minimum. There was no extraction or fat removal necessary. With the biosensor test paraoxon concentrations down to 1 microg/L could be detected in milk. The detection limit for carbaryl was 20 microg/L. Recovery rates for paraoxon and carbaryl in milk samples lay between 89 and 107%. Ten milk samples from local markets were tested both with the biosensor test and with standard chromatographic multiresidue methods. Two milk samples caused AChE inhibition rates of >50%. Accordingly, 4 microg/L tebufenpyrad, 4 microg/L tetraconazole, and 2 microg/L bifenthrin were detected in one of these milk samples. The other milk sample contained 2 microg/L tebufenpyrad.  相似文献