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31.
The hunting behaviour and habitat use of second-calendar-year males (subadult) and grey (adult) males of Montagu's harrier
Circus pygargus were compared in south-east Poland. Subadult males performed cruising flights less frequently than did adult males. In contrast,
subadult males more frequently soared thermals and were harassed more often by other birds. Overall, adult males were more
frequently engaged in hunting activities than subadult males. Additionally, adult males were more successful in trapping prey
than were subadult males. Only 7% (n=92) of trapping attempts by subadult males were successful, compared with 17% (n=126) by grey males. Both adult and subadult males tried to catch prey flushed by foxes Vulpes vulpes. Subadult males were seen begging and pirating from prey-carrying raptors.
Communicated by M.E. dos Santos 相似文献
32.
Lateral diffusion coefficients in membranes measured by resonance energy transfer and a new algorithm for diffusion in two dimensions 下载免费PDF全文
Kuśba J Li L Gryczynski I Piszczek G Johnson M Lakowicz JR 《Biophysical journal》2002,82(3):1358-1372
We describe measurements of lateral diffusion in membranes using resonance energy transfer. The donor was a rhenium (Re) metal-ligand complex lipid, which displays a donor decay time near 3 micros. The long donor lifetime resulted in an ability to measure lateral diffusion coefficient below 10(-8) cm(2)/s. The donor decay data were analyzed using a new numerical algorithm for calculation of resonance energy transfer for donors and acceptors randomly distributed in two dimensions. An analytical solution to the diffusion equation in two dimensions is not known, so the equation was solved by the relaxation method in Laplace space. This algorithm allows the donor decay in the absence of energy transfer to be multiexponential. The simulations show that mutual lateral diffusion coefficients of the donor and acceptor on the order of 10(-8) cm(2)/s are readily recovered from the frequency-domain data with donor decay times on the microsecond timescale. Importantly, the lateral diffusion coefficients and acceptor concentrations can be recovered independently despite correlation between these parameters. This algorithm was tested and verified using the donor decays of a long lifetime rhenium lipid donor and a Texas red-lipid acceptor. Lateral diffusion coefficients ranged from 4.4 x 10(-9) cm(2)/s in 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG) at 10 degrees C to 1.7 x 10(-7) cm(2)/s in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) at 35 degrees C. These results demonstrated the possibility of direct measurements of lateral diffusion coefficients using microsecond decay time luminophores. 相似文献
33.
An investigation of the taste character and intensity of sixproline-containing cylic dipeptides demonstrates that thesecompounds are differentiated largley on the basis of their chemicalconfiguration.
x/ Permanent address: Technical University, 80952 Gdask,Poland 相似文献
34.
Ignacy Z. Siemion Zbigniew Szewczuk Zbigniew S. Herman Zdzislaw Stachura 《Molecular and cellular biochemistry》1981,34(1):23-29
Summary A semi-rigid structural analog of [Leu5] enkephalin, possessing the azo-bridge between Tyr1 and Phe4 residues, was synthesized, along with two other linear enkephalin analogs: [4′-amino Phe4] enkephalin and [4′hydroxyphenyl/-azo Phe4] enkephalin. The results of the determination of the analgesic activity of the synthesized compounds suggest that the biologically
active conformation of the enkephalin molecule should be such that both aromatic rings, Tyr1 and Phe4, are situated in close proximity. 相似文献
35.
Kostov Y Smith DS Tolosa L Rao G Gryczynski I Gryczynski Z Malicka J Lakowicz JR 《Biotechnology progress》2005,21(6):1731-1735
High-sensitivity detection schemes are of great interest for a number of applications. Unfortunately, such schemes are usually high-cost. We demonstrate a low-cost approach to a high-sensitivity detection scheme based on surface plasmon-coupled emission (SPCE). The SPCE of a monomolecular layer of green fluorescent protein (GFP) is reported here. The protein was electrostatically attached to a thin, SiO(2)-protected silver film deposited on a quartz substrate. The visible, directional emission of GFP was observed at a sharp, well-defined angle of 47.5 degrees from the normal to the coupling prism, and the spectrum corresponded to that of GFP. The SPCE resulting from the reverse Kretschmann configuration showed a 12-fold enhancement over the free space fluorescence. The directional emission was 97% p-polarized. The directionality and high polarization can be coupled with the intrinsic spectral resolution of SPCE to be used in the design miniaturized spectrofluorometers. The observation of SPCE in the visible region of the spectrum from a monolayer of protein opens up new possibilities in protein-based sensing. 相似文献
36.
The Ni(II)-MDP-OH system (MDP=methylene diphosphonic acid) and stability constants of complexes formed at ionic strength 0.15M at 298K were established by direct current polarography (DCP) and glass electrode potentiometry (GEP). The final M-L-OH model could only be arrived to by employing recent concept of virtual potentiometry (VP). VP-data were generated from non-equilibrium and dynamic DC polarographic technique. The VP and GEP data were refined simultaneously by software dedicated to potentiometric studies of metal complexes. Species distribution diagrams that were generated for different experimental conditions employed in this work assisted in making the final choice regarding the metal-ligand model. The model established contains ML, ML(2), ML(OH) and ML(OH)(2) with stability constants, as logbeta, 7.94+/-0.02, 13.75+/-0.02, 12.04 (fixed value), and 16.75+/-0.05, respectively. It has been demonstrated that virtual potential must be used in modelling operations (predictions of species formed) when a polarographic signal decreases significantly due to the formation of polarographically inactive species (or formation of inert complexes). The linear free energy relationships that included stability constant logK(1) for Ni(II)-MDP established in this work together with other available data were used to predict logK(1) values for Sm(III) and Ho(III) with MDP. The logK(1) values for Sm(III)-MDP and Ho(III)-MDP were estimated to be 9.65+/-0.10 and 9.85+/-0.10, respectively. 相似文献
37.
Wieslaw A. Kliś Eleonora Nawrocka Ignacy Z. Siemion Andrzej Plech Zdzisław Stachura Zbigniew S. Herman 《Bioorganic chemistry》1979,8(2):255-262
Two analogs of Leu5-enkephalin, (1-O-methyltyrosine,5-leucine)-enkephalin and [1-(3′-amino)-tyrosine,5-leucine]-enkephalin, were synthesized by classical methods. Both analogs show high biological potency after injection into the lateral brain ventricle of the rat. In both cases substitution of the Tyr residue of enkephalin leads to a pronounced prolongation of analgesic action, as compared with the unsubstituted peptide. 相似文献
38.
Pawlikowska-Pawlega B Gruszecki WI Misiak L Paduch R Piersiak T Zarzyka B Pawelec J Gawron A 《Biochimica et biophysica acta》2007,1768(9):2195-2204
Quercetin is a naturally occurring flavonoid that has a lot of beneficial properties to human health. In this report, using the spin label technique, the influence of quercetin on the fluidity of multilamellar DPPC liposomes was studied. The polarity of the environment preferred by quercetin was also examined by determining the dependence of the position of electronic absorption maxima on dielectric properties of different environments. Autofluorescence of quercetin was also used to examine its distribution in cells. An additional aim of the study was to find how quercetin presence affects human skin fibroblasts. The results showed that incorporation of quercetin at physiological pH into DPPC liposomes caused changes in the partition coefficient of the Tempo spin label between water and polar head group phases. By determining the electronic absorption maxima, we observed that the chromophore of quercetin is localized in the polar head region. Fluorescence microscopy of HSF cells showed quercetin presence in the membrane, cytoplasm and inside the nucleus. Ultrastructural observation revealed some changes, especially in membranous structures, after flavonol treatment. From the results we have concluded that quercetin present in the membrane and other structures can cause changes within cells crucial for its pharmacological activity. 相似文献
39.
Ignacy Z. Siemion Tadeusz Wilusz Antoni Polanowski 《Molecular and cellular biochemistry》1984,60(2):159-161
Summary In this report we propose the disulfide bridges alignment in the squash polypeptide trypsin inhibitors. The prediction is based on the extensive homology in the amino acid sequence between these inhibitors and a portion of the wheat germ agglutinin domains for which the position of the disulfide bridges are known. 相似文献
40.
Kitowski VJ 《Cardiovascular diseases》1978,5(4):416-424
Cardiovascular related diseases are the major cause of death in the United States. The primary goal of the physician should be prevention of these diseases; however, once problems occur, a definitive rehabilitation program must be instituted in addition to the medical and surgical treatment. Although risk factors for the development of cardiovascular disease are numerous, statistical reports suggest that control of these factors might delay or prevent such development. This presentation describes the recommended Physical Medicine and Rehabilitation Program for high-risk patients or those with existing cardiovascular disease. The basis of the physical fitness and rehabilitation program is controlled progression-of-energy-expenditure physical activity and exercise in metabolic equivalents (METS). Education plays a key role in decreasing the incidence of cardiovascular disease, and should start at an early age. Adults at high risk of developing cardiovascular disease should be offered medically supervised physical fitness exercise programs, with monitoring where necessary. 相似文献