排序方式: 共有193条查询结果,搜索用时 0 毫秒
1.
2.
3.
Rebekka Dohme Andrew P. King Gwendŵr R. Meredith Meredith J. West 《Ethology : formerly Zeitschrift fur Tierpsychologie》2015,121(4):327-334
This research focused on how adult female brown‐headed cowbirds, Molothrus ater, regulate social feedback on a group level to shape the development of male song. Specifically, females produce rapid wing movements in response to male song, termed ‘wing strokes,’ which have been shown to shape male song and predict song quality. These effects have been documented in captive dyads and triads, but not in more naturalistic flocks, where song development actually occurs. Here, we studied wing stroking in small seminatural flocks of differing female‐to‐male ratios. Despite differences in the number of females and their social selectivity, the same pattern of female feedback emerged in seven of eight flocks: One female produced the majority of wing strokes to male song, making her the primary wing stroker in her flock. Previous studies on large flocks have demonstrated females to facilitate male song improvisation and development if they exhibited higher social selectivity by approaching immature males less. Here, we found that primary wing strokers were indeed more socially selective than non‐primary wing strokers. This research is the first to document social stimulation being facilitated at the group level to ensure that more highly selective females deliver the most feedback. 相似文献
4.
Seminatural grasslands provide habitats for various species and are important for biodiversity conservation. The understanding of the diverse responses of species and traits to different grassland managenient methods is therefore urgently needed. We disentangled the role of grassland management (fertilization and irrigation), vegetation structure (biomass, sward height) and plant quality (protein and fiber content) for Orthoptera communities in lowland hay meadows in Germany. We found vegetation structure to be the most important environmental category in explaining community structure of Orthoptera (species richness, total individuals, fiinctional diversity and species composition). Intensively used meadows (fertilized, irrigated, high plant biomass) were characterized by assemblages with few species, low functional diversity, and low conservation value. Thereby, the relatively moderate fertilizer inputs in our study system of up to -75 kg N/ha/year reduced functional diversity of Orthoptera, while this negative effect of fertilization was not detectable when solely considering taxonomic aspects. We found strong support for a prominent role of plant quality in shaping Orthoptera communities and especially the trait composition. Our findings demonstrate the usefulness of considering both taxonomic and functional comp on ents (functio nal diversity) in biodiversity research and we suggest a stronger involvement of plant quality measures in Orthoptera studies. 相似文献
5.
Iryna Sutter Rebekka Park Alaa Othman Lucia Rohrer Thorsten Hornemann Markus Stoffel Olivier Devuyst Arnold von Eckardstein 《Journal of lipid research》2014,55(8):1730-1737
Sphingosine-1-phosphate (S1P) mediates several cytoprotective functions of HDL. apoM acts as a S1P binding protein in HDL. Erythrocytes are the major source of S1P in plasma. After glomerular filtration, apoM is endocytosed in the proximal renal tubules. Human or murine HDL elicited time- and dose-dependent S1P efflux from erythrocytes. Compared with HDL of wild-type (wt) mice, S1P efflux was enhanced in the presence of HDL from apoM transgenic mice, but not diminished in the presence of HDL from apoM knockout (Apom−/−) mice. Artificially reconstituted and apoM-free HDL also effectively induced S1P efflux from erythrocytes. S1P and apoM were not measurable in the urine of wt mice. Apom−/− mice excreted significant amounts of S1P. apoM was detected in the urine of mice with defective tubular endocytosis because of knockout of the LDL receptor-related protein, chloride-proton exchanger ClC-5 (Clcn5−/−), or the cysteine transporter cystinosin. Urinary levels of S1P were significantly elevated in Clcn5−/− mice. In contrast to Apom−/− mice, these mice showed normal plasma concentrations for apoM and S1P. In conclusion, HDL facilitates S1P efflux from erythrocytes by both apoM-dependent and apoM-independent mechanisms. Moreover, apoM facilitates tubular reabsorption of S1P from the urine, however, with no impact on S1P plasma concentrations. 相似文献
6.
Biedendieck R Beine R Gamer M Jordan E Buchholz K Seibel J Dijkhuizen L Malten M Jahn D 《Applied microbiology and biotechnology》2007,74(5):1062-1073
Fructosyltransferases, like the Lactobacillus reteri levansucrase, are important for the production of new fructosyloligosaccharides. Various His6- and Strep-tagged variants of this enzyme were recombinantly produced and exported into the growth medium using the Gram-positive
bacterium Bacillus megaterium. Nutrient-rich growth medium significantly enhanced levansucrase production and export. The B. megaterium signal peptide of the extracellular esterase LipA mediated better levansucrase export compared to the one of the penicillin
amidase Pac. The combination of protein export via the LipA signal peptide with the coexpression of the signal peptidase gene
sipM further increased the levansucrase secretion. Fused affinity tags allowed the efficient one-step purification of the recombinant
proteins from the growth medium. However, fused peptide tags led to slightly decreased secretion of tested fusion proteins.
After upscaling 2 to 3 mg affinity tagged levansucrase per liter culture medium was produced and exported. Up to 1 mg of His6-tagged and 0.7 mg of Strep-tagged levansucrase per liter were recovered by affinity chromatography. Finally, the purified
levansucrase was shown to synthesize new fructosyloligosaccharides from the novel donor substrates d-Gal-Fru, d-Xyl-Fru, d-Man-Fru, and d-Fuc-Fru.
R. Biedendieck and R. Beine contributed equally to this work. 相似文献
7.
Knox OG Killham K Artz RR Mullins C Wilson M 《Applied and environmental microbiology》2004,70(8):4666-4671
There is much interest in the use of seed-applied bacteria for biocontrol and biofertilization, and several commercial products are available. However, many attempts to use this strategy fail because the seed-applied bacteria do not colonize the rhizosphere. Mechanisms of rhizosphere colonization may involve active bacterial movement or passive transport by percolating water or plant roots. Transport by other soil biota is likely to occur, but this area has not been well studied. We hypothesized that interactions with soil nematodes may enhance colonization. To test this hypothesis, a series of microcosm experiments was carried out using two contrasting soils maintained under well-defined physical conditions where transport by mass water flow could not occur. Seed-applied Pseudomonas fluorescens SBW25 was capable of rhizosphere colonization at matric potentials of -10 and -40 kPa in soil without nematodes, but colonization levels were substantially increased by the presence of nematodes. Our results suggest that nematodes can have an important role in rhizosphere colonization by bacteria in soil. 相似文献
8.
Ross A. Robinson Samuel C. Griffiths Lieke L. van de Haar Tomas Malinauskas Eljo Y. van Battum Pavol Zelina Rebekka A. Schwab Dimple Karia Lina Malinauskaite Sara Brignani Marleen H. van den Munkhof Özge Düdükcü Anna A. De Ruiter Dianne M.A. Van den Heuvel Benjamin Bishop Jonathan Elegheert A. Radu Aricescu R. Jeroen Pasterkamp Christian Siebold 《Cell》2021,184(8):2103-2120.e31
9.
Markwardt ML Kremers GJ Kraft CA Ray K Cranfill PJ Wilson KA Day RN Wachter RM Davidson MW Rizzo MA 《PloS one》2011,6(3):e17896
Cyan fluorescent proteins (CFPs), such as Cerulean, are widely used as donor
fluorophores in Förster resonance energy transfer (FRET) experiments.
Nonetheless, the most widely used variants suffer from drawbacks that include
low quantum yields and unstable flurorescence. To improve the fluorescence
properties of Cerulean, we used the X-ray structure to rationally target
specific amino acids for optimization by site-directed mutagenesis. Optimization
of residues in strands 7 and 8 of the β-barrel improved the quantum yield of
Cerulean from 0.48 to 0.60. Further optimization by incorporating the wild-type
T65S mutation in the chromophore improved the quantum yield to 0.87. This
variant, mCerulean3, is 20% brighter and shows greatly reduced
fluorescence photoswitching behavior compared to the recently described
mTurquoise fluorescent protein in vitro and in living cells. The fluorescence
lifetime of mCerulean3 also fits to a single exponential time constant, making
mCerulean3 a suitable choice for fluorescence lifetime microscopy experiments.
Furthermore, inclusion of mCerulean3 in a fusion protein with mVenus produced
FRET ratios with less variance than mTurquoise-containing fusions in living
cells. Thus, mCerulean3 is a bright, photostable cyan fluorescent protein which
possesses several characteristics that are highly desirable for FRET
experiments. 相似文献
10.