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By fabric | ch
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Tuesday, May 29. 2018
Note: some progressive news... Published almost two years ago ((!) I find it interesting to bring things back and out of their "buzz time", possibly check what happened to it next), the article present some advances in "bionic-leaf". One step closer to the creation of artificial leaves so to say.
The interesting thing is that the research has deepened and continues towards agriculture, on-site soil enrichment to boost growth rather than treating it with fertilizers and chemicals to be transported from far. Behind this, some genetic manipulations though (for good? for bad?): "Expanding the reach of the bionic leaf".
Via MIT Technology Review
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A new system for making liquid fuel from sunlight, water, and air is a promising step for solar fuels.
by Richard Martin
The bionic leaf is one step closer to reality.
Daniel Nocera, a professor of energy science at Harvard who pioneered the use of artificial photosynthesis, says that he and his colleague Pamela Silver have devised a system that completes the process of making liquid fuel from sunlight, carbon dioxide, and water. And they’ve done it at an efficiency of 10 percent, using pure carbon dioxide—in other words, one-tenth of the energy in sunlight is captured and turned into fuel. That is much higher than natural photosynthesis, which converts about 1 percent of solar energy into the carbohydrates used by plants, and it could be a milestone in the shift away from fossil fuels. The new system is described in a new paper in Science.
“Bill Gates has said that to solve our energy problems, someday we need to do what photosynthesis does, and that someday we might be able to do it even more efficiently than plants,” says Nocera. “That someday has arrived.”
In nature, plants use sunlight to make carbohydrates from carbon dioxide and water. Artificial photosynthesis seeks to use the same inputs—solar energy, water, and carbon dioxide—to produce energy-dense liquid fuels. Nocera and Silver’s system uses a pair of catalysts to split water into oxygen and hydrogen, and feeds the hydrogen to bacteria along with carbon dioxide. The bacteria, a microörganism that has been bioengineered to specific characteristics, converts the carbon dioxide and hydrogen into liquid fuels.
Several companies, including Joule Unlimited and LanzaTech, are working to produce biofuels from carbon dioxide and hydrogen, but they use bacteria that consume carbon monoxide or carbon dioxide, rather than hydrogen. Nocera’s system, he says, can operate at lower temperatures, higher efficiency, and lower costs.
Nocera’s latest work “is really quite amazing,” says Peidong Yang of the University of California, Berkeley. Yang has developed a similar system with much lower efficiency. “The high performance of this system is unparalleled” in any other artificial photosynthesis system reported to date, he says.
The new system can use pure carbon dioxide in gas form, or carbon dioxide captured from the air—which means it could be carbon-neutral, introducing no additional greenhouse gases into the atmosphere. “The 10 percent number, that’s using pure CO2,” says Nocera. Allowing the bacteria themselves to capture carbon dioxide from the air, he adds, results in an efficiency of 3 to 4 percent—still significantly higher than natural photosynthesis. “That’s the power of biology: these bioörganisms have natural CO2 concentration mechanisms.”
Nocera’s research is distinct from the work being carried out by the Joint Center for Artificial Photosynthesis, a U.S. Department of Energy-funded program that seeks to use inorganic catalysts, rather than bacteria, to convert hydrogen and carbon dioxide to liquid fuel. According to Dick Co, who heads the Solar Fuels Institute at Northwestern University, the innovation of the new system lies not only in its superior performance but also in its fusing of two usually separate fields: inorganic chemistry (to split water) and biology (to convert hydrogen and carbon dioxide into fuel). “What’s really exciting is the hybrid approach” to artificial photosynthesis, says Co. “It’s exciting to see chemists pairing with biologists to advance the field.”
Commercializing the technology will likely take years. In any case, the prospect of turning sunlight into liquid fuel suddenly looks a lot closer.
Thursday, January 24. 2013
Via MIT Technology Review
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By Katherine Bourzac
Researchers who have used the biomolecule to encode MP3s, text files, and JPEGs say it will be a competitive storage medium in just a few decades.
DNA could someday store more than just the blueprints for life—it could also house vast collections of documents, music, or video in an impossibly compact format that lasts for thousands of years.
Researchers at the European Bioinformatics Institute in Hinxton, U.K., have demonstrated a new method for reliably encoding several common computer file formats this way. As the price of sequencing and synthesizing DNA continues to drop, the researchers estimate, this biological storage medium will be competitive within the next few decades.
The information storage density of DNA is at least a thousand times greater than that of existing media, but until recently the cost of DNA synthesis was too high for the technology to be anything more than a curiosity. Conventional methods of storing digital information for prolonged periods continue to pose problems, however. The magnetic tapes typically used for archival storage become brittle and lose their coating after a few decades. And even if the physical medium used to store information remains intact, storage formats are always changing. This means the data has to be transferred to a new format or it may become unreadable.
DNA, in contrast, remains stable over time—and it’s one format that’s always likely to be useful. “We want to separate the storage medium from the machine that will read it,” says project leader Nick Goldman. “We will always have technologies for reading DNA.” Goldman notes that intact DNA fragments tens of thousands of years old have been found and that DNA is stable for even longer if it’s refrigerated or frozen.
The U.K. researchers encoded DNA with an MP3 of Martin Luther King Jr.’s “I Have a Dream” speech, a PDF of a scientific paper, an ASCII text file of Shakespeare’s sonnets, and a JPEG color photograph. The storage density of the DNA files is about 2.2 petabytes per gram.
Others have demonstrated DNA data storage before. This summer, for example, researchers led by Harvard University genetics professor George Church used the technology to encode a book (see “An Entire Book Stored in DNA”).
The difference with the new work, says Goldman, is that the researchers focused on a practical, error-tolerant design. To make the DNA files, the researchers created software that converted the 1s and 0s of the digital realm into the genetic alphabet of DNA bases, labeled A, T, G, and C. The program ensures that there are no repeated bases such as “AA” or “GG,” which lead to higher error rates when synthesizing and sequencing DNA.
The files were divided into segments, each bookended with an index code that contains information about which file it belongs to and where it belongs within that file—analogous to the title and page number on pages of a book.
The encoding software also ensures some redundancy. Each part of a file is represented in four different fragments, so even if several degrade, it should still be possible to reconstruct the data.
Working with Agilent Technologies of Santa Clara, California, the researchers synthesized the fragments of DNA and then demonstrated that they could sequence them and accurately reconstruct the files. This work is described today in the journal Nature.
Goldman’s group estimates that encoding data in DNA currently costs $12,400 per megabyte, plus $220 per megabyte to read that data back. If the price of DNA synthesis comes down by two orders of magnitude, as it is expected to do in the next decade, says Goldman, DNA data storage will soon cost less than archiving data on magnetic tapes.
Victor Zhirnov, program director for memory technologies at the Semiconductor Research Corporation in Durham, North Carolina, says that because the current cost is so high, data-storing DNA will probably find its earliest use in long-term archives that aren’t accessed frequently. Looking ahead, he says, he can envision “a more aggressive technology” to replace flash, the nonvolatile memory technology found in portable electronics, which is already reaching its scaling limits. The key will be developing entire hardware systems that work with DNA, not just sequencers and synthesizers.
Harvard’s Church says he is working on this very problem. “We can keep incrementally improving our ability to read and write DNA, but I want to jump completely out of that box,” he says. Church is currently developing a system for directly encoding analog signals such as video and audio into DNA, eliminating conventional electronics altogether.
Tuesday, November 20. 2012
Via MIT Technology Review
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What two crustaceans and a timepiece have to do with the future of medical electronics.
In Evgeny Katz’s vision of the future, medical implants will use the human body as a battery. They’ll just run on the same juice that powers us human beings. His lab at Clarkson University has been building a biofuel cell—an energy harvester--that has successfully drawn electrical energy from glucose coursing the blood streams of snails, clams, and now, lobsters.
Human medical implants powered by what we eat are a long way away, but in a new paper, Katz and his team demonstrate how their technology is maturing towards such a reality. That’s where the lobsters come in. Researchers from Clarkson University and the University of Vermont College of Medicine explain how they’ve powered a watch using glucose from two lobsters, connected as batteries would be, in series. They also show that it’s possible to keep a pacemaker ticking with glucose levels usually seen in the human body.
The key to this setup is an enzyme stationed at implanted electrodes made of carbon nanotubes. Together, the two efficiently convert chemical energy from glucose in an animal’s circulatory system to electricity.
In the past, these energy-harvesting biofuel cells have been tested in the ear of rabbits, in the abdomen of insects, in the body cavity of snails and clams. But the lobsters are different. It’s the first time living organisms have powered up a piece of electronics.
With electrodes in their abdomen, the two lobsters powered the watch for an hour, until the lobsters’ glucose levels near the electrode dropped. (They don’t feel any pain, a member of the team has explained, because they don’t have nerve endings where the electrodes were implanted.) The voltage picked up though, and the crustaceans powered the watch for as long as they remained alive in the lab.
People with pacemakers are ideal bio-battery candidates. As an early test of the idea, the team hooked up a pacemaker to an artificial setup resembling the human circulatory system. It contained serum spiked with glucose at different levels--to represent glucose levels in the blood immediately after you hit the gym, or while sitting at your desk at work, or if you’re diabetic. (Serum is blood with the proteins and cells filtered out.)
With its battery removed, the pacemaker became the first of its kind to run solely on glucose derived from body fluid for five hours. It won’t be the last though, Katz and co. have a list of other medical devices waiting their turn.
Tuesday, September 04. 2012
Via MIT Technology Review
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Researchers at Harvard encode information in DNA at a density on par with any other experimental storage method.
DNA can be used to store information at a density about a million times greater than your hard drive, report researchers in Science today. George Church of Harvard Medical School and colleagues report that they have written an entire book in DNA, a feat that highlights the recent advances in DNA synthesis and sequencing.
The team encoded a draft HTML version of a book co-written by Church called Regenesis: How Synthetic Biology Will Reinvent Nature and Ourselves. In addition to the text, the biological bits included the information for modern formatting, images and Javascript, to show that “DNA (like other digital media) can encode executable directives for digital machines,” they write.
To do this, the authors converted the computational language of 0's and 1's into the language of DNA--the nucleotides typically represented by A's, T's G's and C's; the A’s and C’s took the place of 0's and T’s and G’s of 1's. They then used off-the-shelf DNA synthesizers to make 54,898 pieces of DNA, each 159 nucleotides long, to encode the book, which could then be decoded with DNA sequencing.
This is not the first time non-biological information has been stored in DNA, but Church's demonstration goes far beyond the amount of information stored in previous efforts. For example, in 2009, researchers encoded 1688 bits of text, music and imagery in DNA and in 2010, Craig Venter and colleagues encoded a watermarked, synthetic genome worth 7920 bits.
DNA synthesis and sequencing is still too slow and costly to be practical for most data storage, but the authors suggest DNA’s long-lived nature could make it a suitable medium for archival storage.
Erik Winfree, who studies DNA-based computation at Caltech and was a 1999 TR35 winner, hopes the study will stimulate a serious discussion about what roles DNA can play in information science and technology.
“The most remarkable thing about DNA is its information density, which is roughly one bit per cubic nanometer,” he writes in an email.
“Technology changes things, and many old ideas for DNA information storage and information processing deserve to be revisited now -- especially since DNA synthesis and sequencing technology will continue their remarkable advance.”
Personal comment:
Where the living binds to the machine / to computation and where information seems to be the key ingredient. Somehow what Wiener and Shannon told us half a century ago.
Monday, April 02. 2012
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de Marion Wagner
A l’heure actuelle la demande en énergie croît plus vite que l’offre. Selon l’Agence internationale de l’énergie, à l’horizon 2030 les besoins de la planète seront difficiles à satisfaire, tous types d’énergies confondus. Il faudra beaucoup de créativité pour satisfaire la demande.
Vincent Schachter, directeur de la recherche et du développement pour les énergies nouvelles à Total commence son exposé sur la biologie de synthèse. “C’est important de préciser dans quel cadre nous travaillons”. Ses chercheurs redessinent le vivant. Ils s’échinent à mettre au point des organismes microscopiques, des bactéries, capables de produire de l’énergie.
En combinant ingénierie, chimie, informatique et biologie moléculaire, les scientifiques recréent la vie.
Ambition démiurgique
Aucune avancée scientifique n’a incarné tant de promesses : détourner des bactéries en usines biologiques capables de produire des thérapeutiques contre le cancer, des biocarburants ou des molécules capables de dégrader des substances toxiques.
Dans la salle Lamartine de l’Assemblée nationale ce 15 février, le parterre de spécialistes invités par l’Office parlementaire d’évaluation des choix scientifique et techniques (OPECST) est silencieux. L’audition publique intitulée Les enjeux de la biologie de synthèse s’attaque à cette discipline jeune, enjeu déjà stratégique. Geneviève Fioraso, députée de l’Isère, qui l’a organisée, confesse : “J’ai des collègues parlementaires à l’Office qui sont biologistes. Ils me disent qu’ils sont parfois dépassés par ce qui est présenté. Ce sont des questions très complexes d’un point de vue scientifique”.
L’Office, dont la mission est “d’informer le Parlement des conséquences des choix de caractère scientifique et technologique afin, notamment, d’éclairer ses décisions” est composé de parlementaires, députés et sénateurs. Dix-huit élus de chaque assemblée qui représentent proportionnellement l’équilibre politique du Parlement. Assistés d’un conseil scientifique ad hoc ils sont saisis des sujets scientifiques contemporains : la sûreté nucléaire en France, les effets sur la santé des perturbateurs endocriniens, les leçons à tirer de l’éruption du volcan Eyjafjöll…
Marc Delcourt, le PDG de la start-up Global Bioenergies, basée à Evry, prend la parole :
La biologie de synthèse, c’est créer des objets biologiques. Nous nous attachons à transformer le métabolisme de bactéries pour leur faire produire à partir de sucres une molécule jusqu’à maintenant uniquement issue du pétrole, et dont les applications industrielles sont énormes.
Rencontré quelques jours plus tard, Philippe Marlière, le cofondateur de l’entreprise, “s’excuse”. Il donne, lui, une définition “assez philosophique” de la biologie de synthèse : ” Pour moi c’est la discipline qui vise à faire des espèces biologiques, ou tout objet biologique, que la nature n’aurait pas pu faire. Ce n’est pas ‘qu’elle n’a pas fait’, c’est ‘qu’elle n’aurait pas pu faire. Il faut que ce soit notre gamberge qui change ce qui se passe dans le vivant”.
Ce bio-chimiste, formé à l’École Normale Supérieure, assume sans fard une ambition de démiurge, il s’agit de créer la vie de manière synthétique pour supplanter la nature. Il ajoute :
Je ne suis pas naturaliste, je ne fais pas partie des gens qui pensent que la nature est harmonieuse et bonne. Au contraire, la biologie de synthèse pose la nature comme imparfaite et propose de l’améliorer .
Aussi provoquant que cela puisse paraître c’est l’objectif affiché et en partie atteint par la centaine de chercheurs qui s’adonne à la discipline depuis 10 ans en France. Il reprend : “Aussi vaste que soit la diversité des gènes à la surface de la terre, les industriels se sont déjà persuadés que la biodiversité naturelle ne suffira pas à procurer l’ensemble des procédés dont ils auront besoin pour produire de manière plus efficace des médicaments ou des biocarburants. Il va falloir que nous nous retroussions les manches et que nous nous occupions de créer de la bio-diversité radicalement nouvelle, nous-mêmes.”
Biologiste-ingénieur
L’évolution sur terre depuis 3 milliard et demi d’années telle que décrite par Darwin est strictement contingente. La sélection naturelle, écrit le prix Nobel de médecine François Jacob dans Le jeu des possibles “opère à la manière d’un bricoleur qui ne sait pas encore ce qu’il va produire, mais récupère tout ce qui lui tombe sous la main, les objets les plus hétéroclites, bouts de ficelle, morceaux de bois, vieux cartons pouvant éventuellement lui fournir des matériaux […] D’une vieille roue de voiture il fait un ventilateur ; d’une table cassée un parasol. Ce genre d’opération ne diffère guère de ce qu’accomplit l’évolution quand elle produit une aile à partir d’une patte, ou un morceau d’oreille avec un fragment de mâchoire”.
Le hasard de l’évolution naturelle, combiné avec la nécessité de l’adaptation a sculpté un monde “qui n’est qu’un parmi de nombreux possibles. Sa structure actuelle résulte de l’histoire de la terre. Il aurait très bien pu être différent. Il aurait même pu ne pas exister du tout”. Philippe Marlière ajoute, laconique : “A posteriori on a toujours l’impression que les choses n’auraient pas pu être autrement, mais c’est faux, le monde aurait très bien pu exister sans Beethoven”.
Cliquer ici pour voir la vidéo.
Comprendre que l’évolution n’a ni but, ni projet. Et la science est sur le point de pouvoir mettre un terme au bricolage inopérant de l’évolution. Le biologiste, ici, est aussi ingénieur. A partir d’un cahier des charges il définit la structure d’un organisme pour lui faire produire la molécule dont il a besoin. Si la biologie de synthèse en est à ses balbutiements, elle est aussi une révolution culturelle.
Il s’agit désormais de créer de nouvelles espèces dont l’existence même est tournée vers les besoins de l’humanité. “La limite à ne pas toucher pour moi c’est la nature humaine. Je suis un opposant acharné au transhumanisme“, met tout de suite en garde le généticien.
A, T, G, C
Depuis que Francis Crick, James Watson et Rosalind Franklin ont identifié l’existence de l’ADN, l’acide désoxyribonucléique, en 1953, une succession de découvertes ont permis de modifier cet l’alphabet du vivant.
On sait désormais lire, répliquer, mais surtout créer un génome et ses gènes, soit en remplaçant certaines de ses parties, soit en le synthétisant entièrement d’après un modèle informatique. Les gènes, quatre bases azotées, A, T, G et C qui se succèdent le long de chacun des deux brins d’ADN pour former la fameuse double hélice, illustre représentation du vivant. Quatre molécules chimiques qui codent la vie : A, pour adénine, T pour thymine, G pour guanine, et C pour cytosine. Leur agencement détermine l’activité du gène, la ou les protéines pour lesquelles il code, qu’il crée. Les protéines, ensuite, déterminent l’action des cellules au sein des organismes vivants : produire des cheveux blonds, des globules blancs, ou des bio-carburants.
On peut à l’heure actuelle, en quelques clics, acheter sur Internet une base azotée pour 30 cents. Un gène de taille moyenne, chez la bactérie, coûte entre 300 et 500 €, il est livré aux laboratoires dans de petits tubes en plastique translucide. Là il est intégré à un génome qui va générer de nouvelles protéines, en adéquation avec les besoins de l’industrie et de l’environnement.
L’être humain est devenu ingénieur du vivant, il peut transformer de simples êtres unicellulaires, levures ou bactéries en de petites usines qu’il contrôle. C’est le bio-entrepreneur américain Craig Venter qui sort la discipline des laboratoires en annonçant en juin 2010 avoir crée Mycoplasma mycoides, une bactérie totalement artificielle “fabriquée à partir de quatre bouteilles de produits chimiques dans un synthétiseur chimique, d’après des informations stockées dans un ordinateur”.
Si la création a été saluée par ses pairs et les médias, certains s’attachent toutefois à souligner que sa Mycoplasma mycoides n’a pas été crée ex nihilo, puisque le génome modifié a été inséré dans l’enveloppe d’une bactérie naturelle. Mais la manipulation est une grande première.
Tour de Babel génétique
Philippe Marlière a posé devant lui un petit cahier, format A5, où après avoir laissé dériver son regard il prend quelques notes. “Il y a longtemps qu’on essaye de changer le vivant en profondeur. Moi c’est l’aspect chimique du truc qui m’intéresse : où faut-il aller piocher dans la table de Mandeleiev pour faire des organismes vivants ? Jusqu’où sont-ils déformables ? Jusqu’à quel point peut-on les lancer dans des mondes parallèles sur terre ?”. Il jette un coup d’œil à son Schweppes :
Prenez l’exemple de l’eau lourde. C’est une molécule d’eau qui se comporte pratiquement comme de l’eau, et on peut forcer des organismes vivants à y vivre et évoluer. Or il n’y a d’eau lourde nulle part dans l’univers, il n’y a que les humains qui savent la concentrer. On peut créer un microcosme complètement artificiel et être sûr que l’évolution qui a lieu là-dedans n’a pas eu lieu dans l’univers. C’est l’évolution dans des conditions qui n’auraient pas pu se dérouler sur terre, c’est intéressant. La biologie de synthèse est une forme radicale d’alter-mondialisme, elle consiste à dire que d’autres vies sont vraiment possibles, en les changeant de fond en comble.
Ce n’est pas une provocation feinte, ce n’est même pas une provocation. L’homme a à cœur d’être bien compris. Il s’agit de venir à bout de l’évolution darwinienne, pathétiquement coincée à un stade qui n’assure plus les besoins en énergie des 10 milliards d’humains à venir. Il faut pour ça réécrire la vie, son code. Innover dans l’alphabet de quatre lettres, A, C, G et T. Créer une nouvelle biodiversité. Condition sine qua non : ces mondes, le nôtre, le naturel, et le nouveau, l’artificiel, devraient cohabiter sans pouvoir jamais échanger d’informations. Il appelle ça la tour de Babel génétique, où les croisements entre espèces seraient impossibles.
“Les écologistes exagèrent souvent, mais ils mettent en garde contre les risques de dissémination génétique et ils ont raison. Les croisements entre espèces vont très loin. J’ai lu récemment que le chat et le serval sont inter-féconds”. Il estime de la main la hauteur du serval, un félin tacheté, proche du guépard, qui vit en Afrique. Un mètre de haut environ.
Par ailleurs il fallait être superstitieux pour imaginer que le pollen des OGM n’allait pas se disséminer. Le pollen sert à la dissémination génétique ! D’où notre projet, il s’agit de faire apparaître des lignées vivantes pour lesquelles la probabilité de transmettre de l’information génétique est nulle.
Le concept tient en une phrase :
“The farther, the safer : plus la vie artificielle est éloignée de celle que nous connaissons, plus les risques d’échanges génétiques entre espèces diminuent. C’est là qu’il y a le plus de brevets et d’hégémonie technologique à prendre.”
Il s’agit de modifier notre alphabet de 4 lettres, A, C, G et T, pour créer un nouvel ADN, le XNA, clé de la “xénobiologie”:
X pour Xeno, étranger, et biologie. Le sens de cet alphabet ne serait pas lisible par les organismes vivants, c’est ça le monde qu’on veut faire. C’est comme lancer un Spoutnik, c’est difficile. Mais comme disait Kennedy, ‘On ne va pas sur la lune parce que c’est facile, on y va parce que c’est difficile.’
Cliquer ici pour voir la vidéo.
Wednesday, February 22. 2012
Via GizFactory
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Posted by Ujagar Singh on 29 Nov 2011 05:12 PM
Philips,has offered a new genre of living biological lighting product.The subtle glow is generated by using micro organisms from house hold waste.The concept explores the use of bio luminescent bacteria, which are fed with methane and composted material drawn from the methane digester in the Microbial Home system.Alternatively,the cellular light array can be filled with fluorescent proteins that emit different frequencies of light. Philips feel this,in addition to indoor usage,can also be used outdoors,for night time road markings, warning strips on stairs or curbs,exit signs,lights for sensors and so on. Sounds interesting,effectiveness can be gauged only after use.
Thanks Sinan for the tip!
Wednesday, November 23. 2011
Whilst we are pretty much all aware of the implications of 3-D printing as a process of making any arbitrary object at the push of a button, it is exactly what living organisms have been up to since the invention of multicellular life.
Designers at IDEO have teamed up with scientists at the Lim Lab at the University of California, San Francisco to envision a “provocation” (that’s designer-ese for thought experiment) in which they explore the possibilities of exploiting known properties of microorganisms to literally “grow” the products we use every day.
What is particularly interesting about these future scenarios is where we once thought about computer systems that evolve through immense network of both physical and conceptual parameters, where one influence the other as in the case of Nervous System’s process of “growing objects”, the process of printing may eventually evolve into processes of actual physical growing. These two systems, of digital creation and of the biological one may eventually merge, creating an ecology of both digital and physical networks that communicate and feed of one another.
“One day if we understand how to program [living organisms,] we can encode things beyond software–we could encode materiality” says Carey. “That’s already happening in nature, but we have no idea how to do that ourselves.”
Time to move away from mimicry?
Read more on Fast Company >Training Bacteria To Grow Consumer Goods
More on this topic at syntheticaesthetics.org
Friday, July 29. 2011
Three new experiments highlight the power of optogenetics—a type of genetic engineering that allows scientists to control brain cells with light.
Karl Deisseroth and colleagues at Stanford University used light to trigger and then alleviate social deficits in mice that resemble those seen in autism. Researchers targeted a highly evolved part of the brain called the prefrontal cortex, which is well connected to other brain regions and involved in planning, execution, personality and social behavior. They engineered cells to become either hyperactive or underactive in response to specific wavelengths of light.
According to a report from Stanford;
The experimental mice exhibited no difference from the normal mice in tests of their anxiety levels, their tendency to move around or their curiosity about new objects. But, the team observed, the animals in whose medial prefrontal cortex excitability had been optogenetically stimulated lost virtually all interest in engaging with other mice to whom they were exposed. (The normal mice were much more curious about one another.)
The findings support one of the theories behind the neurodevelopmental deficits of autism and schizophrenia; that in these disorders, the brain is wired in a way that makes it hyperactive, or overly susceptible to overstimulation. That may explain why many autistic children are very sensitive to loud noises or other environmental stimuli.
"Boosting their excitatory nerve cells largely abolished their social behavior," said Deisseroth, [associate professor of psychiatry and behavioral sciences and of bioengineering and the study's senior author]. In addition, these mice's brains showed the same gamma-oscillation pattern that is observed among many autistic and schizophrenic patients. "When you raise the firing likelihood of excitatory cells in the medial prefrontal cortex, you see an increased gamma oscillation right away, just as one would predict it would if this change in the excitatory/inhibitory balance were in fact relevant."
In a second study, from Japan, researchers used optogenetics to make mice fall asleep by engineering a specific type of neuron in the hypothalamus, part of the brain that regulates sleep. Shining light on these neurons inhibited their activity, sending the mice into dreamless (or non-REM) sleep. The research, published this month in the Journal of Neuroscience, might shed light on narcolepsy, a disorder of sudden sleep attacks.
Rather than making mice fall asleep, a third group of researchers used optogenetics disrupt sleep in mice, which in turn affected their memory. Previous research has shown that sleep is important for consolidating, or storing, memories, and that diseases characterized by sleep deficits, such as sleep apnea, often have memory deficits as well. But it has been difficult to analyze the effect of more subtle disruptions to sleep.
The new study shows that "regardless of the total amount of sleep, a minimal unit of uninterrupted sleep is crucial for memory consolidation," the authors write in the study published online July 25 in the Proceedings of the National Academy of Sciences.
They genetically engineered a group of neurons involved in switching between sleep and wake to be sensitive to light. Stimulating these cells with 10-second bursts of light fragmented the animals' sleep without affecting total sleep time or quality and composition of sleep.
According to a press release from Stanford;
After manipulating the mice's sleep, the researchers had the animals undergo a task during which they were placed in a box with two objects: one to which they had previously been exposed, and another that was new to them. Rodents' natural tendency is to explore novel objects, so if they spent more time with the new object, it would indicate that they remembered the other, now familiar object. In this case, the researchers found that the mice with fragmented sleep didn't explore the novel object longer than the familiar one — as the control mice did — showing that their memory was affected.
The findings, "point to a specific characteristic of sleep — continuity — as being critical for memory," said [H. Craig Heller, professor of biology at Stanford and one of the authors of the study.]
Thursday, July 28. 2011
Via Pruned
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by Alexander Trevi
(Photo courtesy of the Center for PostNatural History.)
We've always liked the work produced by the Center for PostNatural History, so it's great to hear that they've recently opened a central location in Pittsburgh, Pennsylvania, to house their collections, a ragtag bunch that usually travels around from galleries to museums to more atypical exhibition spaces. It's not Plum Island though.
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