| 1. |
- Bunk, Richard, et al.
(författare)
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Towards a 'nano-traffic' system powered by molecular motors
- 2003
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Ingår i: Microelectronic Engineering. - 1873-5568. ; 67-8, s. 899-904
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we reconstructed in vitro the behavior of two motor proteins-myosin and actin-responsible for the mechanical action of muscle cells. By transferring this in vivo system to an artificial environment, we were able to study the interaction between the proteins in more detail, as well as investigating the central mechanism of force production. Nm-patterning by e-beam lithography (EBL) could restore parts of the in vivo protein order, essential for potential nanotechnological applications. Much work was put into establishing the necessary compatibility between the biological and nano-lithographical processes. A range of EBL-resists were tested for protein compatibility. One particular kind (MRL-6000.1XP) supported good actin filament motility, while another (PMMA-950) behaved in the opposite way. Taking advantage of these findings, nm-sized lines were created in a double-layer structure of the two resists. The lines were found to act as binding sites for myosin, and as rectifying guides for the linearized motion of actin filaments. Velocities around 5 mum/s were measured. (C) 2003 Elsevier Science B.V. All rights reserved.
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| 2. |
- Lee, J., et al.
(författare)
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Two species of Lumbricillus (Enchytraeidae, Annelida) new to Antarctica
- 2019
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Ingår i: Polar Research. - : Norwegian Polar Institute. - 0800-0395 .- 1751-8369. ; 38
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Tidskriftsartikel (refereegranskat)abstract
- The intertidal fauna of the Antarctic Peninsula has a relatively high species diversity, due to its warmer environment compared to other parts of Antarctica. Marine oligochaetes are, in general, one of the most diverse and ecologically important benthic organism groups, at least in the littoral zone. Antarctica has been one of the least studied areas with regard to oligochaete diversity. Here we report two Lumbricillus species (Lumbricillus antarcticus Stephenson, 1932 and Lumbricillus sejongensis sp. nov.) new to Antarctica, found in a tidal pool on the Barton Peninsula, King George Island. The diversity of this genus remains poorly known for Antarctica and the Subantarctic islands, and what we know is based on a few patchy studies.
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| 3. |
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| 4. |
- Bunk, Richard, et al.
(författare)
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Actomyosin motility on nanostructured surfaces
- 2003
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Ingår i: Biochemical and Biophysical Research Communications. - 1090-2104. ; 301:3, s. 783-788
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Tidskriftsartikel (refereegranskat)abstract
- We have here, for the first time, used nanofabrication techniques to reproduce aspects of the ordered actomyosin arrangement in a muscle cell. The adsorption of functional heavy meromyosin (HMM) to five different resist polymers was first assessed. One group of resists (MRL-6000.1XP and ZEP-520) consistently exhibited high quality motility of actin filaments after incubation with HMM. A second group (PMMA-200, PMMA-950, and MRI-9030) generally gave low quality of motility with only few smoothly moving filaments. Based on these findings electron beam lithography was applied to a bi-layer resist system with PMMA-950 on top of MRL-6000.1XP. Grooves (100-200 nm wide) in the PMMA layer were created to expose the MRL-6000.1XP surface for adsorption of HMM and guidance of actin filament motility. This guidance was quite efficient allowing no U-turns of the filaments and approximately 20 times higher density of moving filaments in the grooves than on the surrounding PMMA.
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| 5. |
- Klinth, J, et al.
(författare)
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Cardiotonic bipyridine amrinone slows myosin-induced actin filament sliding at saturating [MgATP]
- 2003
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Ingår i: Journal of Muscle Research and Cell Motility. - 0142-4319. ; 24:1, s. 15-32
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Tidskriftsartikel (refereegranskat)abstract
- Previously reported effects of amrinone on skeletal muscle function suggest that the drug reduces the rate constant of myosin cross-bridge dissociation. We have used the in vitro motility assay to further elucidate the mechanism underlying this effect and to aid these studies a new, improved,. lament tracking software was developed in the Matlab(TM) environment. The experiments were carried out at 30degreesC using heavy meromyosin from fast rabbit muscle and rhodamine-phalloidin labeled actin. laments. A slowing effect of amrinone on. lament sliding velocity at 1 mM MgATP was observed at drug concentrations >0.3 mM. This effect showed signs of saturation at the highest drug concentrations (1-2 mM) that could be readily tested. The sliding velocity exhibited hyperbolic dependence on [ MgATP] with a V-max of 7.2 +/- 0.9 mum/s and a K-M of 0.18 +/- 0.02 mM. Amrinone (1 mM) reduced V-max by 32 +/- 5% (P < 0.01) and K-M by 42 &PLUSMN; 8% (P < 0.05; n = 4). These results are accounted for in the most straightforward way by a model where amrinone acts directly on the actomyosin system and reduces the rate constant of MgADP release. Such a well-defined effect on the myosin cross-bridge cycle makes the drug a potentially useful pharmacological tool for further studies of myosin function both in vitro and in the ordered. lament array of a living muscle fiber.
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| 6. |
- Klinth, J. E., et al.
(författare)
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A novel application of multi-wavelength TIRF spectroscopy for real time monitoring of antithrombin interactions with immobilized heparin
- 2006
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Ingår i: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 21:10, s. 1973-80
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Tidskriftsartikel (refereegranskat)abstract
- Real time interactions of antithrombin (AT) with Corline Heparin Surfaces (CHS) with one and two layers of heparin conjugate have been examined using a multi-wavelength TIRF spectroscopy technique with continuous flow. Fluorescently labeled AT, adsorbed from citrated human blood plasma, showed significantly higher signals on CHS compared to the cationic surface used to attach the heparin conjugate. The AT binding to CHS was very stable, also after exposure to soluble heparin at a concentration of 1.5 IU/mL. Only a few percent of the bound AT were displaced from the surfaces by AT present in plasma after long-term exposure to plasma. In contrast, larger amounts of the freshly added AT had adsorbed to the surfaces, especially to the surface with two layers of heparin conjugate, indicating the presence of unsaturated AT binding sites. The amount of AT bound to the different surfaces was quantified after elution using an enzyme immunoassay (EIA). Characteristic emission spectra of proteins and fluorophores of labeled proteins, obtained at the surfaces after a long-term exposure to plasma, confirmed their presence at the surfaces. The multi-wavelength TIRF technique proved to be a useful tool when combined with other techniques to study the time course of interactions of fluorescently labeled proteins with biomaterials, even in a complex environment such as plasma.
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| 7. |
- Klinth, Jeanna E, et al.
(författare)
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Impairment of the biomechanical compliance of P pili : a novel means of inhibiting uropathogenic bacterial infections?
- 2012
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Ingår i: European Biophysics Journal. - Berlin : Springer. - 0175-7571 .- 1432-1017. ; 41:3, s. 285-295
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Tidskriftsartikel (refereegranskat)abstract
- Gram-negative bacteria often initiate their colonization by use of extended attachment organelles, so called pili. When exposed to force, the rod of helix-like pili has been found to be highly extendable, mainly attributed to uncoiling and recoiling of its quaternary structure. This provides the bacteria with the ability to redistribute an external force among a multitude of pili, which enables them to withstand strong rinsing flows, which, in turn, facilitates adherence and colonization processes critical to virulence. Thus, pili fibers are possible targets for novel antibacterial agents. By use of a substance that compromises compliance of the pili, the ability of bacteria to redistribute external forces can be impaired, so they will no longer be able to resist strong urine flow and thus be removed from the host. It is possible such a substance can serve as an alternative to existing antibiotics in the future or be a part of a multi-drug. In this work we investigated whether it is possible to achieve this by targeting the recoiling process. The test substance was purified PapD. The effect of PapD on the compliance of P pili was assessed at the single organelle level by use of force-measuring optical tweezers. We showed that the recoiling process, and thus the biomechanical compliance, in particular the recoiling process, can be impaired by the presence of PapD. This leads to a new concept in the search for novel drug candidates combating uropathogenic bacterial infections-"coilicides", targeting the subunits of which the pilus rod is composed.
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