Archive for April, 2017
Researchers at Standford University develop multi-level programming language for biotic games using swarms of microorganisms
Computer games are a ubiquitous pastime and a great example of how a single programming language give rise to a myriad of games. But what about biotic games? How could you program biological systems to function in an interactive way? Biotic games are interactive applications that interface biology and computer science for the promotion of science. The Riedel-Kruse Lab at Standford specialize in developing biotic games that use light to control swarms of Euglena gracilis—a phototaxic microorganism that avoids—and can direct, capture, and move whole swarms or individual organisms.
But programming swarms of microorganisms is no easy task. Swarms exhibit collective behaviour and therefore need to be controlled through local context rather than at the individual level. In their recent publication, the Riedel-Kruse Lab developed a set of hierarchical programming abstractions that allows swarms of Euglena within a biological processing unit (BPU; i.e., chip, microscope, and light stimuli) to be programmed in a single and efficient language at the stimulus, swarm, and system levels. At the lowest level, stimulus space programming (which the authors analogize to machine code) allows the programmer to have direct control over the various stimuli (e.g., turn left light on for 3 s), independent of the Euglena. Higher level programming at the swarm and system levels are more general and commands are given in terms of what the user wants the Euglena or system to do. For instance, swarm space commands direct the swarm in different operations such as move, split, and combine. System space commands incorporate conditional statements that can be used to confine a specific number of Euglena to a certain region or to clear Euglena from the field of view, for example.
While Lam et al. used this new language to program a biotic game, this new language and approach to swarm programming could be generalized for any type of swarm and stimuli. One application could be to program swarms to construct complex structures on the microscale. In future, by increasing access to BPUs through cloud computing and releasing this new programming language it will be possible for hobbyists and researchers alike to write new programs and applications. And maybe this is just the beginning of a revolution like the one ushered in by the release of the personal microcomputer.
To download the full article for free* click the link below:
Device and programming abstractions for spatiotemporal control of active micro-particle swarms
Amy T. Lam, Karina G. Samuel-Gama, Jonathan Griffin, Matthew Loeun, Lukas C. Gerber, Zahid Hossain, Nate J. Cira, Seung Ah Lee and Ingmar H. Riedel-Kruse
Lab Chip, 2017,17, 1442-1451
*Free to access until 24th May 2017.
About the Webwriter
Darius Rackus is finishing his Ph.D. at the University of Toronto working in the Wheeler Lab. His research interests are in combining sensors with digital microfluidics for healthcare applications.
Lab on a Chip is delighted to be a sponsor of:
Microfluidics, Physics & Chemistry of – Gordon Research Conference.
The event will take place on 4th – 9th June 2017 in Barga, Italy.
The conference brings together scientists, engineers and clinicians to discuss and advance cutting edge knowledge of microfluidics. Microfluidics are small scale systems that could be used to diagnose disease, enable unique physical and biological experiments and create new materials.
The goal of the 2017 meeting is to bridge the gap between scientists and engineers focused on fundamentals and those translating fundamental work into new applications. The conference is sure to spark animated discussion, new interactions and fruitful collaborations!
The conference will consist of topical sessions and active poster sessions. Topics include:
- Point of Care Technologies
- Nucleic Acid Analysis and Next Generation Sequencing
- Fields, Forces, and Flows
- Field-Structure Interactions
- Wearable and Implantable Systems
- Cell Mechanics
- Living Systems
- 3D Printing
The event is being chaired by Dino Di Carlo (UCLA, Lab on a Chip Editorial Board member) and Catherine M. Klapperich (Boston University) and vice chaired by Hang Lu (Georgia Institute of Technology, Lab on a Chip Associate Editor) and Cullen R. Buie (MIT).
Just like Google maps, DNA maps can tell us the distance between two genes, and allow us to zoom in on the region of interest. DNA mapping started with human genome project, where DNA sequencing techniques opened a way to unveil the genetic information. However, determining the unique places and repetitions of four “chemical letters” found in our DNA—together known as the genes—is a difficult mission due to temperature, pH, and pressure sensitivity of the molecule. DNA mapping technology allows for easy identification of large structural variations in DNA and therefore provides long-range information of the genome and can more.
Optical DNA mapping has emerged in the past decade as a powerful alternative to other DNA sequencing techniques since it can easily be applied with reduced risk of DNA damage. Over 100000 basepairs of DNA molecules, which are quite difficult to handle with other techniques, are labeled, stretched, and rendered in a single image. The stretching part is done using nanochannels (and therefore lab-on-a-chip technology), while the labeling part can be done by either enzymatic or affinity-based techniques (Figure 1). The concept and applications of optical DNA mapping has recently been very well explained in a tutorial review written by Vilhelm Müller and Fredrik Westerlund from Chalmers University of Technology in Sweden.
In enzymatic labelling nucleotides at particular regions on a single DNA strand are replaced by new ones using a DNA polymerase. The replacement nucleotides are then utilized to incorporate fluorophores into the DNA strand and allow for visualization. Nicking enzymes and methyl-transferases present two different approaches to employ enzymatic labelling process. While the use of differently colored fluorophores extends the applicability of this technique, the final resolution depends on the degree of stretching and the density of fluorophores on the region.
Affinity-based labelling is based on non-covalent interactions which can be enabled by either denaturation mapping or competitive binding. In denaturation mapping, DNA is heated to discriminate between the bases by their different bond energies. While G-C-basepairs still hold both strands of DNA—due to 3 hydrogen bonds holding them—, A-T-basepairs will melt—due to 2 hydrogen bonds holding them—. At this stage, an intercalating fluorescent dye can be linked to G-C-basepairs, allowing for imaging. Competitive binding relies on the usage of a fluorescent intercalating dye and a molecule selective for either A-T or G-C regions. Therefore, fluorescent dye cannot bind where the selective molecules have already bound. An optical map of DNA molecules can be obtained in this way. Affinity-based labelling is also highly dependent on the degree of stretching.
Optical DNA mapping techniques are useful tools for a wide range of applications from assembly of complex genomes to bacterial plasmid epidemiology. The concept opens up exciting research directions as it allows for automation of whole analysis using lab-on-a-chip systems and observation of the results using smartphones.
To download the full article for free* click the link below:
Vilhelm Müller and Fredrik Westerlund
Lab Chip, 2017, Articles
*Free to access until 5th May 2017.
Burcu Gumuscu is a postdoctoral fellow in BIOS Lab on a Chip Group at University of Twente in The Netherlands. Her research interests include development of microfluidic devices for next generation sequencing, compartmentalized organ-on-chip studies, and desalination of water on the microscale.