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Storms RF, Carere C, Musters R, Hulst R, Verhulst S, Hemelrijk CK. A robotic falcon induces similar collective escape responses in different bird species. J R Soc Interface 2024; 21:20230737. [PMID: 38689546 PMCID: PMC11061643 DOI: 10.1098/rsif.2023.0737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 02/13/2024] [Accepted: 03/15/2024] [Indexed: 05/02/2024] Open
Abstract
Patterns of collective escape of a bird flock from a predator are fascinating, but difficult to study under natural conditions because neither prey nor predator is under experimental control. We resolved this problem by using an artificial predator (RobotFalcon) resembling a peregrine falcon in morphology and behaviour. We imitated hunts by chasing flocks of corvids, gulls, starlings and lapwings with the RobotFalcon, and compared their patterns of collective escape to those when chased by a conventional drone and, in case of starlings, hunted by wild peregrine falcons. Active pursuit of flocks, rather than only flying nearby by either the RobotFalcon or the drone, made flocks collectively escape more often. The RobotFalcon elicited patterns of collective escape in flocks of all species more often than the drone. Attack altitude did not affect the frequency of collective escape. Starlings escaped collectively equally often when chased by the RobotFalcon or a wild peregrine falcon. Flocks of all species reacted most often by collective turns, second most often by compacting and third by splitting into subflocks. This study demonstrates the potential of an artificial aerial predator for studying the collective escape behaviour of free-living birds, opening exciting avenues in the empirical study of prey-predator interactions.
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Affiliation(s)
- Rolf F. Storms
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Claudio Carere
- Department of Ecological and Biological Sciences, University of Tuscia, Viterbo, Italy
| | | | - Ronja Hulst
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Simon Verhulst
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Charlotte K. Hemelrijk
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
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Abstract
Maternal androgen exposure has potent effects on offspring development. As substantial levels of maternal androgens are deposited in avian egg yolks, avian eggs are frequently used to study maternal effects, with a strong focus on post-natal development. However, the underlying pathways are largely unknown. Since the hormones are taken up during the embryonic phase, and these are rapidly metabolized by avian embryos into metabolites such as etiocholanolone, we studied the effects of yolk androgens (testosterone and androstenedione) and their metabolite etiocholanolone during the first few days of embryonic development. As embryonic heart rate is often used as an indicator of embryonic development, we measured the heart rate from day 3 to day 6 of incubation by using a shell-less culture technique in rock pigeon eggs (Columba livia). Increased androgen exposure increased heart rate, and increased etiocholanolone mimicked this effect, albeit in a small sample size. This indicates that exposure to maternal androgens increases embryonic overall metabolism which may account for the developmental outcomes found in previous studies such as increased growth. Moreover, etiocholanolone is likely to be an important metabolite in a non-genomic pathway underlying the androgen-mediated maternal effect.
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Affiliation(s)
- Yuqi Wang
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Bernd Riedstra
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Ronja Hulst
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Roy Noordhuis
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Ton Groothuis
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
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Haas M, Audouy S, Muizebelt I, Smisterová J, Engberts JBFN, Hoekstra D, Storm G, Hulst R. In-vivo delivery of DNA and protein using conceptually new cationic, sunfish', amphiphiles. J Control Release 2005; 101:401. [PMID: 15822236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Affiliation(s)
- M Haas
- BioMaDe, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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Smisterová J, Wagenaar A, Stuart MC, Polushkin E, ten Brinke G, Hulst R, Engberts JB, Hoekstra D. Molecular shape of the cationic lipid controls the structure of cationic lipid/dioleylphosphatidylethanolamine-DNA complexes and the efficiency of gene delivery. J Biol Chem 2001; 276:47615-22. [PMID: 11583999 DOI: 10.1074/jbc.m106199200] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pyridinium amphiphiles, abbreviated as SAINT, are highly efficient vectors for delivery of DNA into cells. Within a group of structurally related compounds that differ in transfection capacity, we have investigated the role of the shape and structure of the pyridinium molecule on the stability of bilayers formed from a given SAINT and dioleoylphosphatidylethanolamine (DOPE) and on the polymorphism of SAINT/DOPE-DNA complexes. Using electron microscopy and small angle x-ray scattering, a relationship was established between the structure, stability, and morphology of the lipoplexes and their transfection efficiency. The structure with the lowest ratio of the cross-sectional area occupied by polar over hydrophobic domains (SAINT-2) formed the most unstable bilayers when mixed with DOPE and tended to convert into the hexagonal structure. In SAINT-2-containing lipoplexes, a hexagonal topology was apparent, provided that DOPE was present and complex assembly occurred in 150 mm NaCl. If not, a lamellar phase was obtained, as for lipoplexes prepared from geometrically more balanced SAINT structures. The hexagonal topology strongly promotes transfection efficiency, whereas a strongly reduced activity is seen for complexes displaying the lamellar topology. We conclude that in the DOPE-containing complexes the molecular shape and the nonbilayer preferences of the cationic lipid control the topology of the lipoplex and thereby the transfection efficiency.
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Affiliation(s)
- J Smisterová
- Department of Membrane Cell Biology, University of Groningen, Faculty of Medical Sciences, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
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van Bommel KJ, de Jong MR, Metselaar GA, Verboom W, Huskens J, Hulst R, Kooijman H, Spek AL, Reinhoudt DN. Complexation and (templated) synthesis of rhenium complexes with cyclodextrins and cyclodextrin dimers in water. Chemistry 2001; 7:3603-15. [PMID: 11560332 DOI: 10.1002/1521-3765(20010817)7:16<3603::aid-chem3603>3.0.co;2-e] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Several small, lipophilic rhenium complexes form inclusion complexes with native beta-cyclodextrin (beta-CD) and beta-CD dimers. Association constants larger than 10(9)M(-1) were obtained using dimers. The use of beta-CD also enabled the synthesis of these rhenium complexes in water, in excellent yields, through complexation of the otherwise insoluble corresponding ligands. The influence of the reaction time and temperature on the configuration of the reaction products has been investigated in depth for one of these complexes. Using a beta-CD dimer, it proved possible to specifically template the formation of one configuration. The strength of the complexes of the rhenium complexes in cyclodextrin dimers may allow radiolabeling of biomolecules.
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Affiliation(s)
- K J van Bommel
- Laboratory of Supramolecular Chemistry and Technology, MESA+ Research Institute, University of Twente, Enschede, The Netherlands
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Stamps JP, Ottink B, Visser JM, van Duynhoven JP, Hulst R. Difftrain: a novel approach to a true spectroscopic single-scan diffusion measurement. J Magn Reson 2001; 151:28-31. [PMID: 11444933 DOI: 10.1006/jmre.2001.2352] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Diffusion-ordered spectroscopy (DOSY) has gained considerable attention over the past decade as a useful tool for calculating diffusion-related parameters or in the analysis of complex (reaction) mixtures. A major drawback of the established methods are the relatively long recording times needed to acquire the spectra, excluding the monitoring of rapidly progressing reactions and (hence) measurements of less stable components. In order to overcome these shortcomings a new pulse sequence, Difftrain, has been developed. The sequence involves stimulated echo attenuation, multilow flip angle excitation, and multiple sampling of the FID during the longitudinal storage. The calculated diffusion parameters obtained by Difftrain were compared with those obtained by the established sequence BPPSTE (bipolar pulse pair stimulated echo) and were in good agreement. For systems with moderate to good signal-to-noise ratios the Difftrain building block yields significant saving in recording time (single-shot acquisition instead of acquiring n-different gradients strengths), thus opening up new applications in nonequilibrium systems and screening of compositions and/or interactions of (larger) compound arrays.
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Affiliation(s)
- J P Stamps
- Department of Chemical Analysis, University of Twente, 7500 AE Enschede, The Netherlands
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Abstract
The calix[4]arene platform was used for the syntheses of novel rhenium(V) complexes, that may have potential applications as radiopharmaceuticals. The reaction of ReO(PPh3)2Cl3 with tetradentate N2O2-calix[4]arene ligand 8 in ethanol gave the novel mixed-ligand rhenium complex 9 with the structure ReO(N2O2-calix)OEt. The configuration was elucidated by using a number of 1H NMR techniques. In 9, the ethoxy ligand could be easily and quantitatively exchanged for another monodentate ligand to give complex 12. Tetradentate N2S2-calix[4]arene ligand 15 formed the rhenium complex 16 either via reaction with ReO(PPh3)2Cl3 in an organic solvent or by reaction with rhenium gluconate in an aqueous solution. Complex 16 showed good stability in phosphate-buffered saline solution (37 degrees C, 5 d). The crystal structures of a mono- and a bimetallic complex were determined. The bimetallic N2O2-calixarene complex dimer 11 crystallized in the monoclinic space group C2/c, with a = 38.963(5) A, b = 23.140(6) A, c = 27.382(6) A, beta = 128.456(10) degrees, V = 19,333(7) A3, Z = 8, and final R = 0.0519. The monometallic N2S2 model complex 17 crystallized in the monoclinic space group Cc, with a = 15.715(2) A, b = 12.045(2) A, c = 20.022(3) A, beta = 94.863(12) degrees, V = 3776.3(10) A3, Z = 4, and final R = 0.0342.
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Affiliation(s)
- K J van Bommel
- Laboratory of Supramolecular Chemistry and Technology, MESA+ Research Institute, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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Bevers HAJM, Hulst R. Analysis of alkyl sulfonates and carboxylates using high performance ion chromatography. Chromatographia 2000. [DOI: 10.1007/bf02490448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
Several geminal bis-urea compounds were synthesised by means of an acid-catalysed condensation of various benzaldehydes with different monoalkylureas. Many of these compounds form thermoreversible gels with a number of organic solvents at very low concentrations (<3mM) and which are stable to temperatures higher than 100 degrees C. Electron microscopy revealed a three-dimensional (3D) network of intertwined fibres, which are several tens of micrometers long and have a width ranging from approximately 30 to 300 nm. The possible aggregate forms and aggregate symmetries were evaluated by means of molecular mechanics calculations. 1H NMR, 2D NMR, 13C NMR and 13C-CP/MAS NMR techniques were used to obtain information about the aggregation and possible aggregate symmetry of geminal bis-ureas in solution, in the gel state, and in the solid state.
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Affiliation(s)
- FS Schoonbeek
- Department of Organic and Molecular Inorganic Chemistry Stratingh Institute, University of Groningen, The Netherlands
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Janssen MJ, Hulst R, Kellogg RM, Hendriks MM, Ensing K, de Zeeuw RA. Fluorescent-labeled ligands for the benzodiazepine receptor. Part 1: Synthesis and characterization of fluorescent-labeled benzodiazepines. Pharmazie 2000; 55:42-8. [PMID: 10683870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Because radioactive labeled ligands in receptor assays have several disadvantages, we synthesized a number of fluorescent-labeled benzodiazepines. Several fluorophores were attached at different positions of 1,4-benzodiazepine molecules in order to assess the impact of the fluorophores and their coupling position on the affinity for the benzodiazepine receptor. Besides the 1,4-benzodiazepines, the 1,2-annelated 1,4-benzodiazepines were also used for labeling. A metabolite of flumazenil (18), desethylflumazenil (Ro15-3890, 19), was labeled with the fluorophore 4-bromomethyl-7-methoxycoumarin, with and without the incorporation of a spacer chain, yielding the methyl-methoxycoumarin (Mmc) derivatives Mmc-Ro15-3890 (20a) and Mmc-O-CO-(CH2)3-Ro15-3890 (20b), respectively. After the synthesis, the fluorescent-labeled benzodiazepines were purified by HPLC, using an analytical RP-C18 column. For the purification of 20b, the chromatographic system was optimized, using multi-criteria decision making (MCDM) techniques. The binding affinities for the benzodiazepine receptor and the fluorescence characteristics were determined for the resulting products.
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Affiliation(s)
- M J Janssen
- Department of Analytical Chemistry and Toxicology, University Centre for Pharmacy, Wageningen, The Netherlands
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Woerdenbag HJ, Lutke LR, Bos R, Stevens JF, Hulst R, Kruizinga WH, Zhu YP, Elema ET, Hendriks H, van Uden W, Pras N. Isolation of two cytotoxic diterpenes from the fern Pteris multifida. Z NATURFORSCH C 1996; 51:635-8. [PMID: 8921632 DOI: 10.1515/znc-1996-9-1006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
From aerial parts of the fern Pteris multifida Poir. (Polypodiaceae) two diterpenes, entkaurane-2 beta, 16 alpha-diol and ent-kaur-16-ene-2 beta, 15 alpha-diol, were isolated by repeated column chromatography using silica gel and silica gel impregnated with silver nitrate. The structures were confirmed by spectroscopic methods. Both compounds showed a moderate cytotoxicity to Ehrlich ascites tumour cells.
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Affiliation(s)
- H J Woerdenbag
- Department of Pharmaceutical Biology, University Centre for Pharmacy, Groningen Institute for Drug Studies (GIDS), University of Groningen, The Netherlands
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