SciTech #ScienceSunday Digest – 17/2015.
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Human embryo CRISPR, More accurate CRISPR, Programmable DNA photonics, DNA logic gates, Multifunctional neural probes, MRI Temporal boost, Protein structure algorithms, Emotionally aware machines, Invisible perceptual illusions, Single molecule switches.
1. CRISPR to Modify Human Embryos
Biggest news of the week goes to the Chinese team who used CRISPR methods to produce genetically modified human embryos http://www.nature.com/news/chinese-scientists-genetically-modify-human-embryos-1.17378. The group used non-viable (extra chromosomes), pre-implantation embryos from local fertility clinics and used CRISPR-Cas9 to edit and replace a defective ß-thalassemia gene that typically causes a blood disorder. The group achieve low conversion rates and noted a large number of off-target mutations that resulted. However, several commentators noted that the group used an older version of CRISPR (newer versions are far more accurate) and these non-viable cells are probably not an optimal model.
2. Engineering Even Greater Accuracy into CRISPR
In closely related news newer, accurate versions of CRISPR have been made 25-times even more accurate http://www.eurekalert.org/pub_releases/2015-04/hu-iai042315.php. The new CRISPR is depended on a specific molecule to be active, which is provided to the cells of interest for a relatively short period of time, and so ensures that the CRISPR system is only active for a short period of time. This severely limits the chances of off-target modifications. This work builds on prior studies to create CRISPR systems that require longer (and hence more specific) genetic sequences to recognise and seeks to more subtly alter the cellular equilibrium dynamics of CRISPR-Cas9 enzymes. The team predict that further improvements will lead to CRISPR systems that induce chance mutations at a rate below the level of natural chance mutations that the cell produces on a daily basis anyway.
3. Programmable Matter with DNA Origami
A new modification to self-assembled DNA origami technology delivers the ability to create programmable, tunable fluorescent arrays http://phys.org/news/2015-04-cradle-silver-nanoclusters-synthetic-dna.html. This is achieved via two parts, (i) generating DNA nanotubes with defined positioning sites; in this case with spacings of 7nm, and (ii) generating silver nanoclusters bound to complementary DNA strands that bind the nanoclusters to the nanotube. The nanoclusters all have the same number of atoms and depending on the preparation and binding of DNA the number of atoms can be controlled to produce clusters tuned to fluoresce at different wavelengths of light, from green-blue to infrared.
4. Fuzzy & Boolean Logic Gates Made of DNA
In related news self-assembled DNA origami structures have been demonstrated that can sense two environmental signals (different oligonucleotides and miRNAs) and produce fluorescent outputs corresponding to Boolean logic gates AND, NAND, OR, NOR, XOR, NXOR http://www.nanowerk.com/spotlight/spotid=39795.php. There are a few different labs pursuing DNA computation in this way and good to see competition heating up. Possible applications for this particular embodiment include programmed biosensors that enter cells and only deliver a lethal drug payload if they successfully detect one or more cancer biomarkers for example.
5. Multifunctional Neural Probes for Interfacing the Brain
Neural probes are becoming increasingly sophisticated as evidenced by these fibers and probes that are able to carry light, sense-collect-and-transmit electricity, and also deliver drugs http://www.technologyreview.com/photoessay/536806/a-swiss-army-knife-for-neuroscience/. Such fibers can both stimulate the brain in various ways and also record the resulting activity and allows researchers to controllably alter activity in different ways to see what the effect is. The fabrication process for the probes is quite innovative and involves forming different polymers in the desired pattern and then extruding and shrinking these into tiny fibers.
6. Boosting Temporal Resolution for MRI
Recent advances in MRI technology provide a boost in temporal resolution that allows image capture at 100 frames per second – this can facilitate for example the detailed capture of the complex anatomical coordination that is necessary for a person to sing http://beckman.illinois.edu/news/2015/04/new-super-fast-mri-technique. Such dynamic real-time recordings offering both high spatial and temporal resolution hasn’t been possible until now, and in this application offers new insights into the complex dynamics of the neuromuscular system and larynx in order to better understand changes that occur due to various influences such as aging and disease.
7. Improved Algorithms for Generating 3D Structures from 2D Images
A new image-processing algorithm results in a 100,000-fold speedup in determining 3D structures for proteins from sets of 2D images http://www.technologyreview.com/view/536976/an-algorithm-set-to-revolutionize-3-d-protein-structure-discovery/. The technique utilises (i) electron cryomicroscopy in which a purified protein solution is is frozen into a thin-film one molecule thick, and (ii) transmission electron microscopy in which the film is bombarded with electrons and those that pass through generate images or “shadowgrams” of the molecules in the film. The molecule structure is unknown and orientation is random. Generating the 3D structure from up to 200,000 images used to take two weeks on 300 cores, but now can be done in under 24 hours on a single workstation.
8. Adapting to Machines that Know How You Feel
Wired had a good piece this week covering Affectiva and the coming ubiquity of computers that know and can respond to your emotional state http://www.wired.com/2015/04/computers-can-now-tell-feel-face/. Affectiva is offering its system to developers to help create a broad range of applications predominantly (for now) based on determining fine emotional nuances on faces. The promise here includes dynamic entertainment that responds to your emotions to give you a different experience to someone with different emotions, assisting those with emotion-identification handicaps to better understand people, automatically determine the emotional content of video, assist wearers of HUDs to determine a person’s emotion they may be trying to hide, targeting advertising to people based on their emotional state, and many many others.
9. The Perceptual Illusion of an Invisible Body
An interesting new psychological experiment explores the perceptual illusion on participants of having an invisible body http://ki.se/en/news/scientists-create-the-sensation-of-invisibility. Participants were instructed to look downwards as they wore a stereoscopic head mounted display, which received video input from a pair of binocular cameras that were pointed downwards towards the floor. A researcher then simultaneously touched the person’s body with a brush while touching the corresponding areas in empty space under the cameras with another brush. In less than a minute most people had altered body-maps and perceived the brush-touching-empty-air as actually touching themselves, and this was confirmed via measured stress response when a surprise knife was thrust into the same spot of empty space. I’m always fascinated by how easily malleable our sense of embodiment is.
10. Towards Single Molecule Switches
A new candidate molecule approximately 3nm in size has been demonstrated to function as a single-molecule electronic switch http://www.hzdr.de/db/Cms?pOid=44032&pNid=0. The molecule possesses two stable states, one of which is an insulator and the other a conductor. The group was able to successfully switch the molecule into the “on” conductive state via light, which allowed current to flow between the two nanowire electrodes it was connected to. They can’t yet switch the molecule back to the “off” insulating state but are confident of achieving this in future.
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