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| 2. |
- Bengtsson, Elina, et al.
(författare)
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Altered Structural State of Actin Filaments Upon MYOSIN II Binding
- 2015
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Ingår i: Biophysical Journal. - : Biophysical Society. - 0006-3495 .- 1542-0086. ; 108:2 Suppl. 1, s. 299A-300A
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The paths of actin filaments propelled over a heavy meromyosin (HMM) surface in the in vitro motility assay (IVMA) can statistically be described by a path persistence length (LPP) and has been hypothesized to be proportional to the flexural rigidity of the filaments. Here, we have studied the LPP at high (130 mM) ionic strength along with the persistence length of actin filaments in solution (LPS) to elucidate how HMM binding affects the flexural rigidity of actin filaments. Characterization and control of material properties, such as the path persistence length, is useful in engineered devices that takes advantages of the function of the muscle contractile proteins e.g. for biocomputation. It has been suggested that myosin binding reduces Lpp for phalloidin stabilizedact in filaments. This is consistent with the results presented here where the phalloidin stabilized actin filaments rigidity is reduced to the level of phalloidin free actin filaments in the IVMA. Further, reducing the MgATP concentration in the IVMA would increase the HMM head density along the actin filament hence making the effect of myosin binding more pronounced. A reduced [MgATP] from 1 mM to 0.02-0.05 mM did indeed reduce the LPP from 10-12 mm to 6-7 mm for both phalloidin-stabilized and phalloidin free actin filaments. Additionally, we found a negative correlation between the LPS and the [HMM]/actin ratio. However, this [HMM] dependent reduction observed in LPS was too small to account for the reduction in LPP seen with reduced [MgATP] in the IVMA. Monte-Carlo simulations and theoretical analysis revealed that the large reduction in LPP is consistent with the idea that every head attachment adds an extra angular displacement.(Support from EU-FP7-FET-ABACUS grant number 613044).
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| 3. |
- Bengtsson, Elina, et al.
(författare)
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Myosin-Induced Gliding Patterns at Varied [MgATP] Unveil a Dynamic Actin Filament
- 2016
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 111:7, s. 1465-1477
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Tidskriftsartikel (refereegranskat)abstract
- Actin filaments have key roles in cell motility but are generally claimed to be passive interaction partners in actin-myosin -based motion generation. Here, we present evidence against this static view based on an altered myosin-induced actin filament gliding pattern in an in vitro motility assay at varied [MgATP]. The statistics that characterize the degree of meandering of the actin filament paths suggest that for [MgATP] >= 0.25 mM, the flexural rigidity of heavy meromyosin (HMM)-propelled actin filaments is similar (without phalloidin) or slightly lower (with phalloidin) than that of HMM-free filaments observed in solution without surface tethering. When [MgATP] was reduced to <= 0.1 mM, the actin filament paths in the in vitro motility assay became appreciably more winding in both the presence and absence of phalloidin. This effect of lowered [MgATP] was qualitatively different from that seen when HMM was mixed with ATP-insensitive, N-ethylmaleimide-treated HMM (NEM-HMM; 25-30%). In particular, the addition of NEM-HMM increased a non-Gaussian tail in the path curvature distribution as well as the number of events in which different parts of an actin filament followed different paths. These effects were the opposite of those observed with reduced [MgATP]. Theoretical modeling suggests a 30-40% lowered flexural rigidity of the actin filaments at [MgATP] <= 0.1 mM and local bending of the filament front upon each myosin head attachment. Overall, the results fit with appreciable structural changes in the actin filament during actomyosin-based motion generation, and modulation of the actin filament mechanical properties by the dominating chemomechanical actomyosin state.
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| 4. |
- Elofsson, Katarina, et al.
(författare)
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The impact of climate information on milk demand : Evidence from a field experiment
- 2016
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Ingår i: Food Policy. - : Elsevier BV. - 0306-9192 .- 1873-5657. ; 58, s. 14-23
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that carbon labelling of food, on voluntary or non-voluntary basis, could reduce emissions of greenhouse gases. However, there is limited empirical evidence on the influence of such labels on consumer purchases. The purpose of this study was to investigate whether voluntary carbon labelling affects the demand for milk. A randomized field experiment was conducted in 17 retail stores in Sweden, where a sign provided consumers with qualitative information about the carbon impact of climate-certified milk. The results suggest that the sign increased the demand for the climate-certified milk by approximately 6-8%, and the result is robust to alternative model specifications. The effect is entirely driven by large stores, such as supermarkets. We find no statistically significant impact on total milk sales, and the dataset is too small to verify the consequences for other milk brands. The effect on the demand for the labelled milk is short-lived.
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| 5. |
- Nicolau, Dan V., Jr., et al.
(författare)
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Parallel computation with molecular-motor-propelled agents in nanofabricated networks
- 2016
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 113:10, s. 2591-2596
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Tidskriftsartikel (refereegranskat)abstract
- The combinatorial nature of many important mathematical problems, including nondeterministic-polynomial-time (NP)-complete problems, places a severe limitation on the problem size that can be solved with conventional, sequentially operating electronic computers. There have been significant efforts in conceiving parallel-computation approaches in the past, for example: DNA computation, quantum computation, and microfluidics-based computation. However, these approaches have not proven, so far, to be scalable and practical from a fabrication and operational perspective. Here, we report the foundations of an alternative parallel-computation system in which a given combinatorial problem is encoded into a graphical, modular network that is embedded in a nanofabricated planar device. Exploring the network in a parallel fashion using a large number of independent, molecular-motor-propelled agents then solves the mathematical problem. This approach uses orders of magnitude less energy than conventional computers, thus addressing issues related to power consumption and heat dissipation. We provide a proof-of-concept demonstration of such a device by solving, in a parallel fashion, the small instance {2, 5, 9} of the subset sum problem, which is a benchmark NP-complete problem. Finally, we discuss the technical advances necessary to make our system scalable with presently available technology.
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| 7. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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