| 1. |
- Volpe, Giovanni, 1979, et al.
(författare)
-
Roadmap for optical tweezers
- 2023
-
Ingår i: Journal of Physics-Photonics. - : IOP Publishing. - 2515-7647. ; 5:2
-
Tidskriftsartikel (refereegranskat)abstract
- Optical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space exploration.
|
|
| 2. |
- Ahmadpour, Doryaneh, 1973, et al.
(författare)
-
Inhibition of MAPK Hog1 Results in Increased Hsp104 Aggregate Formation Probably through Elevated Arsenite Influx into the Cells, an Approach with Numerous Potential Applications
- 2014
-
Ingår i: American Journal of Molecular Biology. - : Scientific Research Publishing, Inc.. - 2161-6620 .- 2161-6663. ; 4:2, s. 59-71
-
Tidskriftsartikel (refereegranskat)abstract
- Arsenic is a highly toxic and carcinogenic metalloid widely dispersed in the environment, contaminating water and soil and accumulating in crops. Paradoxically, arsenic is also part of modern therapy and employed in treating numerous ailments and diseases. Hence, inventing strategies to tune cellular arsenic uptake based on purpose is striking. Here, we describe an approach in which the arsenite uptake can be increased using a MAPK inhibitor. Employing microfluidic flow chambers in combination with optical tweezers and fluorescent microscopy, we elevated the influx of arsenite into the yeast Saccharomyces cerevisiae cells following short-term treatment with a Hog1 kinase inhibitor. The increase in arsenite uptake was followed on arsenite triggered redistribution of a reporter protein, Hsp104-GFP, which was imaged over time. The effect was even more pronounced when the yeast mother and daughter cells were analyzed disjointedly, an opportunity provided owing to single-cell analysis. Our data firstly provide a strategy to increase arsenite uptake and secondly show that arsenite triggered aggregates, previously shown to be sites of damaged proteins, are distributed asymmetrically and less accumulated in daughter cells. Inventing approaches to tune arsenite uptake has a great value for its use in environmental as well as medical applications.
|
|
| 3. |
- Babazadeh, Roja, et al.
(författare)
-
The yeast osmostress response is carbon source dependent
- 2017
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1
-
Tidskriftsartikel (refereegranskat)abstract
- Adaptation to altered osmotic conditions is a fundamental property of living cells and has been studied in detail in the yeast Saccharomyces cerevisiae. Yeast cells accumulate glycerol as compatible solute, controlled at different levels by the High Osmolarity Glycerol (HOG) response pathway. Up to now, essentially all osmostress studies in yeast have been performed with glucose as carbon and energy source, which is metabolised by glycolysis with glycerol as a by-product. Here we investigated the response of yeast to osmotic stress when yeast is respiring ethanol as carbon and energy source. Remarkably, yeast cells do not accumulate glycerol under these conditions and it appears that trehalose may partly take over the role as compatible solute. The HOG pathway is activated in very much the same way as during growth on glucose and is also required for osmotic adaptation. Slower volume recovery was observed in ethanol-grown cells as compared to glucose-grown cells. Dependence on key regulators as well as the global gene expression profile were similar in many ways to those previously observed in glucose-grown cells. However, there are indications that cells re-arrange redox-metabolism when respiration is hampered under osmostress, a feature that could not be observed in glucose-grown cells. © 2017 The Author(s).
|
|
| 4. |
- Gustavsson, Anna-Karin, 1986, et al.
(författare)
-
Sustained glycolytic oscillations in individual isolated yeast cells
- 2012
-
Ingår i: Febs Journal. - : Wiley. - 1742-464X. ; 279:16, s. 2837-2847
-
Tidskriftsartikel (refereegranskat)abstract
- Yeast glycolytic oscillations have been studied since the 1950s in cell-free extracts and intact cells. For intact cells, sustained oscillations have so far only been observed at the population level, i.e. for synchronized cultures at high biomass concentrations. Using optical tweezers to position yeast cells in a microfluidic chamber, we were able to observe sustained oscillations in individual isolated cells. Using a detailed kinetic model for the cellular reactions, we simulated the heterogeneity in the response of the individual cells, assuming small differences in a single internal parameter. This is the first time that sustained limit-cycle oscillations have been demonstrated in isolated yeast cells. Database ?The mathematical model described here has been submitted to the JWS Online Cellular Systems Modelling Database and can be accessed at free of charge.
|
|
| 5. |
- Hamngren Blomqvist, Charlotte, 1984, et al.
(författare)
-
A Single-Cell Study of a Highly Effective Hog1 Inhibitor for in Situ Yeast Cell Manipulation
- 2014
-
Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 5:1, s. 81-96
-
Tidskriftsartikel (refereegranskat)abstract
- We present a single cell study of a highly effective Hog1 inhibitor. For this application, we used sequential treatment of a Saccharomyces cerevisiae cell array, with the Hog1 inhibitor and osmotic stress. For this purpose, a four-inlet microfluidic chamber with controlled introduction of two different cell strains within the same experimental setting and a subsequent rapid switching between treatments was designed. Multiple cell strains within the same experiment is a unique feature which is necessary for determining the expected absent cellular response. The nuclear translocation of the cytosolic MAPK, Hog1, was monitored by fluorescence imaging of Hog1-GFP on a single-cell level. An optical tweezers setup was used for controlled cell capture and array formation. Nuclear Hog1-GFP localization was impaired for treated cells, providing evidence of a congenial microfluidic setup, where the control cells within the experiments validated its appropriateness. The chamber enables multiple treatments with incubation times in the order of seconds and the possibility to remove either of the treatments during measurement. This flexibility and the possibility to use internal control cells ensures it a valuable scientific tool for unraveling the HOG pathway, similar signal transduction pathways and other biological mechanisms where temporal resolution and real time imaging is a prerequisite.
|
|
| 6. |
|
|
| 7. |
- Persson, Martin, 1979, et al.
(författare)
-
Probing the elasticity of single yeast cells with holographic optical tweezers.
- 2013
-
Ingår i: Optics in the Life Sciences Congress Technical Digest. - 9781557529664
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The elasticity of single yeast cells is probed using optical force measurement in a holographic optical tweezers setup. The measurements reveal differences in cell wall /membrane stability due to the absence of various proteins.
|
|
| 8. |
- Abbaszadehbanaeiyan, Amin, et al.
(författare)
-
Design and fabrication of high-throughput application-specific microfluidic devices for studying single-cell responses to extracellular perturbations
- 2013
-
Ingår i: Proc. SPIE 8765, Bio-MEMS and Medical Microdevices, 87650K. ; 8765
-
Konferensbidrag (refereegranskat)abstract
- Single cell analysis techniques provide a unique opportunity of determining the intercellular heterogeneity in a cell population, which due to genotype variations and different physiological states of the cells i.e. size, shape and age, cannot be retrieved from averaged cell population values. In order to obtain high-value quantitative data from single-cell experiments it is important to have experimental platforms enabling high-throughput studies. Here, we present a microfluidic chip, which is capable of capturing individual cells in suspension inside separate traps. The device consists of three adjacent microchannels with separate inlets and outlets, laterally connected through the V-shaped traps. Vshaped traps, with openings smaller than the size of a single cell, are fabricated in the middle (main) channel perpendicular to the flow direction. Cells are guided into the wells by streamlines of the flows and are kept still at the bottom of the traps. Cells can then be exposed to extracellular stimuli either in the main or the side channels. Microchannels and traps of different sizes can be fabricated in polydimethylsiloxane (PDMS), offering the possibility of independent studies on cellular responses with different cell types and different extracellular environmental changes. We believe that this versatile high-throughput cell trapping approach will contribute to further development of the current knowledge and information acquired from single-cell studies and provide valuable statistical experimental data required for systems biology. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
|
|
| 9. |
- Abbaszadehbanaeiyan, Amin, 1983, et al.
(författare)
-
Hydrodynamic Cell Trapping for High Throughput Single-Cell Applications
- 2013
-
Ingår i: Micromachines. - : MDPI AG. - 2072-666X. ; 4:4, s. 414-430
-
Tidskriftsartikel (refereegranskat)abstract
- The possibility to conduct complete cell assays under a precisely controlled environment while consuming minor amounts of chemicals and precious drugs have made microfluidics an interesting candidate for quantitative single-cell studies. Here, we present an application-specific microfluidic device, cellcomb, capable of conducting high-throughput single-cell experiments. The system employs pure hydrodynamic forces for easy cell trapping and is readily fabricated in polydimethylsiloxane (PDMS) using soft lithography techniques. The cell-trapping array consists of V-shaped pockets designed to accommodate up to six Saccharomyces cerevisiae (yeast cells) with the average diameter of 4 μm. We used this platform to monitor the impact of flow rate modulation on the arsenite (As(III)) uptake in yeast. Redistribution of a green fluorescent protein (GFP)-tagged version of the heat shock protein Hsp104 was followed over time as read out. Results showed a clear reverse correlation between the arsenite uptake and three different adjusted low = 25 nL min−1, moderate = 50 nL min−1, and high = 100 nL min−1 flow rates. We consider the presented device as the first building block of a future integrated application-specific cell-trapping array that can be used to conduct complete single cell experiments on different cell types.
|
|
| 10. |
- Abbaszadehbanaeiyan, Amin, et al.
(författare)
-
Liver-lobule-on-a-chip microfluidic device for long-term maintenance of human hepatocytes
- 2017
-
Ingår i: Presented at EMBEC’17 & NBC’17 (conference), 11-15 juni 2017, Tampere, Finland.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The pressing need for in vitro micro-physiological platforms for drug discovery and development has given rise to the emergence of organs-on-a-chip (OOC) microfluidic devices. The possibility of reproducing the native niche of each organ in a dynamic microenvironment offers advantages over current static 2D and 3D cell culture techniques. Constant removal of waste products and metabolites from the culture while providing a continuous flow of growth media is one of the major benefits of dynamic OOC systems. Additionally, physiological flow conditions can be introduced to the system allowing for reproduction of the vasculature parameters of organs in vitro. The liver is the main organ in the body for drug clearance and detoxification. The key role of the liver in the metabolism system of the human body makes it an interesting target organ to mimic in the dynamic OOC systems. Here we present a PDMS-based liver-lobule-on-a-chip microfluidic device designed to reproduce the geometrical as well as convection-diffusion mass transport aspects of the classic liver lobule. We cultured human induced pluripotent stem cell (hiPSC)-derived hepatocytes (CDI) in honeycomb cell culture chambers with involvement of two different extra-cellular matrix (ECM) materials. In the first approach, microfluidic devices were pre-treated with rat-tail collagen I and cell suspension was seeded in the devices afterwards. Cells were seeded in the devices with the supplemented plating medium (RPMI) and culture for 5 days. The medium was changed to the supplemented mainte-nance media (RPMI) thereafter and replaced every other day. In the second approach, we mixed the cell suspension with 20% diluted GeltrexTM (15 mg/ml) in a 1:1 ratio. Cells were seeded in the supplemented plating media (RPMI) and were kept under conditions identical to approach one during the hepatocyte maturation period. After day 5, however, the formulation of maintenance media was changed to supplemented DMEM/F12. Cultures were kept viable and functional for at least three weeks. In both scenarios cells formed 3D tissue-like structures and formation of bile canaliculi network was observed in the devices versus 2D static cultures. The compatibility of the device for drug toxicity applications and multi-cellular in vitro organotype construction is currently under exploration.
|
|
