inhoudelijkonderzoek

How do bacteria communicate?

Let's say you're coming home after a long day of work. The house is quiet, but the lights are on, so you call out, "Anybody home?" Your kids respond with joyous shouts, and your spouse greets you from the kitchen. In this way, you have accounted for your family members. You've also gotten a sense of their needs -- if your spouse had been trapped beneath fallen furniture, he or she would have cried out for help. And if your kids had observed your arrival by asking if you'd brought home pizza, then you would know they were hungry.

You've probably heard animal noises that indicated some form of communication, but it wasn't until fairly recently that we learned that even some of the smallest organisms on Earth, bacteria, can communicate with each other. In the 1960s, researchers observed that bacteria known as Vibrio fischeri exhibited greater amounts of luminescence as the bacterial population grew. Emanating a glow takes a lot of metabolism, and the scientists determined that the bacteria were able to preserve their energy until they realized that there were enough of them to make a really good glow. Researchers called this phenomenon quorum-sensing -- the bacteria communicate to determine the size of their community.

But how? It turns out that the bacteria emit autoinducers, or signaling molecules similar to pheromones. The concentration of autoinducers in any given area indicates the size of the population. But bacteria don't just communicate with their own kind -- in recent years, scientists have determined that bacteria have a receptor for species-specific autoinducers, as well as a receptor for the signals sent out by all other kinds of bacteria. Not only does this indicate that many species of bacteria beyond the bioluminescent ones have the capability to communicate, it means that all bacteria in close proximity are probably chatting it up. Much like we account for our loved ones at the end of the day, the bacteria are taking roll as well.

Why does this matter? Knowing how bacteria communicate could impact how we fight disease. Many bacteria begin to wreak havoc on the human body only once there are enough to overwhelm the immune system. Instead of waiting for bacteria to attack us, drug manufacturers are interested in developing a way to scramble the wires of bacterial communication before it starts. That way, bacteria will never know that they've achieved the kind of threshold necessary to establish an infection in the body.

http://science.howstuffworks.com/life/cellular-microscopic/bacteria-communication.htm

Nanorobot laat medicijnen gecontroleerd in lichaam los
Wetenschappers hebben een nanorobot ontwikkeld die in het lichaam kan worden gestuurd en een molecuul kan vasthouden en loslaten. De nanorobot kan gebruikt worden voor het afleveren van medicijnen.

Dat schrijven onderzoekers uit de Verenigde Staten, Denemarken en Italië gezamenlijk in een recente publicatie.

De nanorobot, die de wetenschappers DNA Nanocage noemen, kan biomoleculen bij zich houden en op een gecontroleerd moment in het lichaam loslaten. De 'kooi' is zo klein dat de moleculen er niet onderweg uitvallen.
Door de temperatuur te verlagen sluit de kooi zich om de molecuul. Als vervolgens de temperatuur in het lichaam wordt verhoogd, gaat één kant van de DNA-kooi open en worden de moleculen losgelaten.

Medicijnen
De wetenschappers zijn er van overtuigd dat de technologie in de toekomst gebruikt kan worden voor het afleveren van medicijnen.

Hierdoor kunnen doses worden verlaagd en kunnen medicijnen tegen bijvoorbeeld kankertumoren veel gerichter worden ingezet zonder gezonde onderdelen van het lichaam aan te tasten.

Het kooitje is slechts vijftien tot twintig nanometer breed. Dat komt neer op 0,000015 tot 0,00002 millimeter. "Het mooie van werken met DNA is dat je het kan ontwerpen zoals je wilt", aldus één van de onderzoekers.

"Als we grotere of kleinere medicijnen of moleculen willen verpakken, is het gewoon een kwestie van het langer of korter maken van de DNA-strengen." Eerdere microrobots voor in het menselijk lichaam waren veel groter (zo'n 0,1 millimeter) waardoor medicijnen per ongeluk te vroeg losgelaten zouden kunnen worden.

http://www.nu.nl/tech/3645987/nanorobot-laat-medicijnen-gecontroleerd-in-lichaam-los.html

Pupillen en inbeelding

'Menselijke pupillen reageren op inbeelding'
Menselijke pupillen reageren op ingebeelde scènes, zo blijkt uit nieuw wetenschappelijk onderzoek.

Als mensen zich een beeld voorstellen van een heldere of een donkere omgeving reageren hun pupillen daarop door kleiner of groter te worden.
Hieruit blijkt dat pupillen niet alleen worden beïnvloed door de omgeving, maar ook door de gedachten van mensen.

Tot die conclusie komen onderzoekers van de Universiteit van Oslo in het wetenschappelijk tijdschrift Psychological Science.

Driehoeken
Bij de studie moesten proefpersonen eerst op een computerscherm kijken naar driehoeken met een verschillende helderheid. De reactie van hun pupillen werd in kaart gebracht met een speciaal eyetracking-apparaat.

Zoals verwacht verwijdden de pupillen zich bij het kijken naar donkere driehoeken en werden ze kleiner als de driehoek op het scherm een fel licht uitstraalde.
Bij een vervolgexperiment keken de proefpersonen niet naar het scherm, maar kregen ze de opdracht om zich de driehoeken in te beelden, die ze eerder op het scherm hadden gezien. Hun pupillen bleken ook te reageren op deze ingebeelde scènes.

Hersenen
Als ze aan een heldere driehoek dachten, werden hun pupillen kleiner. Bij een gedachte aan een donkere driehoek, verwijdden hun pupillen zich.
Volgens de wetenschappers suggereren de bevindingen dat we met verbeeldingskracht onze hersenen in zekere zin om de tuin leiden. "Mensen kunnen hun pupillen namelijk niet vrijwillig kleiner of groter maken", aldus hoofdonderzoeker Bruno Laeng op nieuwssite Phys.org.
"Daarom is het feit dat pupillen kleiner worden door denkbeeldig licht een sterke aanwijzing dat verbeeldingskracht is gebaseerd op dezelfde hersenprocessen die optreden als we iets echt waarnemen."

http://www.nu.nl/wetenschap/3645182/menselijke-pupillen-reageren-inbeelding-.html

A new method of data storage that converts information into DNA sequences allows you to store the contents of an entire computer hard-drive on a gram's worth of E. coli bacteria...and perhaps considerably more than that.

http://io9.com/5699767/bioencryption-can-store-almost-a-million-gigabytes-of-data-inside-bacteria

Significance

All animals are populated by microbes, and, contrary to popular belief, most microbes appear highly beneficial to their hosts. They are critical in animal nutrition and immune defense, and they can serve as important catalysts for the effective development and functioning of host tissues. It also is becoming increasingly clear that they can contribute to host behavior. It has been hypothesized that one way they do so is by producing the components of chemical signals that animals use to communicate. We tested and confirmed first predictions of this hypothesis in hyenas, demonstrating that the bacterial and odor profiles of hyena scent secretions covaried and that both profiles varied with characteristics of hyenas known to be communicated through their chemical signals.

Abstract

All animals harbor beneficial microbes. One way these microbes can benefit their animal hosts is by increasing the diversity and efficacy of communication signals available to the hosts. The fermentation hypothesis for mammalian chemical communication posits that bacteria in the scent glands of mammals generate odorous metabolites used by their hosts for communication and that variation in host chemical signals is a product of underlying variation in the bacterial communities inhabiting the scent glands. An effective test of this hypothesis would require accurate surveys of the bacterial communities in mammals’ scent glands and complementary data on the odorant profiles of scent secretions—both of which have been historically lacking. Here we use next-generation sequencing to survey deeply the bacterial communities in the scent glands of wild spotted and striped hyenas. We show that these communities are dominated by fermentative bacteria and that the structures of these communities covary with the volatile fatty acid profiles of scent secretions in both hyena species. The bacterial and volatile fatty acid profiles of secretions differ between spotted and striped hyenas, and both profiles vary with sex and reproductive state among spotted hyenas within a single social group. Our results strongly support the fermentation hypothesis for chemical communication, suggesting that symbiotic bacteria underlie species-specific odors in both spotted and striped hyenas and further underlie sex and reproductive state-specific odors among spotted hyenas. We anticipate that the fermentation hypothesis for chemical communication will prove broadly applicable among scent-marking mammals as others use the technical and analytical approaches used here.

Symbiotic bacteria appear to mediate hyena social odors

Biostorage Scheme Turns E. Coli Bacteria into Hard Drives

E. coli gets a bad rap – probably due to the violent illness it induces – but a group of Chinese University students in Hong Kong have found a novel and potentially reputation-changing use for the bacteria: data storage. The team has devised a way to encrypt and store information in the DNA of bacteria to such an effective degree that they say just one gram of E. coli could store the same amount of data as 450 two-terabyte hard drives.

Biostorage, or the storing of data in living things, is nascent but not new, having been around for about a decade. But earlier efforts at encoding data into DNA have been incremental – for instance, a few years back a team of Japanese researchers encoded Einstein's relativity equation into the DNA of bacteria, demonstrating that it was possible but otherwise not pushing the field forward.

Three years later the strides taken by the Hong Kong team are far more significant, showing that not only text but also images, music, and video can be stored within cells. The team devised a means of compressing data into chunks that can be placed in different cells and mapped so that it can be easily located later, much as CPUs chop and store data in fragments. They've even developed a three-tier security system that allows them to encrypt the data in an unhackable way, making data stored on their bacterial systems impervious to cyber threats.

In theory, bacterial biostorage systems could hold vast amounts of data in very small spaces, and since the bacteria keep replicating they could feasibly store data reliably for millennia. But the applications don't end there; the team is exploring ways their techniques could be used to encode extra information into organisms like genetically modified crops to create a sort of "bio barcode" that would identify the provenance of a certain strain of GM vegetable or help track the spread of certain GM crops designs.