Now is more than an instant

What do we mean when we say “now”? How long is a “now”? It feels pretty quick, so quick that by the time you’ve read the word “now” it’s already past.

But in fact “now” actually encompasses everything that happened in the last 80 milliseconds. This timespan is important for connecting the cause and effect of our own actions, and to some extent our understanding of time, our sense of self and our inability to tickle ourselves.

80 milliseconds is approximately the time it takes to integrate the sensory input from all the different parts of your body. If you touch your nose and your toe simultaneously, you feel them happening at the same time, even though the nerve signals take longer to come from your foot than your face – up to 80 milliseconds longer.

As another example, our brains can actually process sound quicker than they can process images, yet when a hand claps we see it move and hear the sound simultaneously. That is of course, until the person clapping gets so far away that the difference between the speed of sound and light causes them to be more than 80 milliseconds out of synch, at which point they suddenly become disconnected.

You can compare this with film and television. Video is typically screened at 25 frames per second, which means that 80 millisecond roughly corresponds to 2 frames. This is actually quite helpful for video editors and broadcasters, as it gives some leeway for synchronisation of sound and vision before it looks weird.

But this 80 millisecond span is not totally fixed: it can also be sped up and slowed down. I don’t mean some sort of slow motion, Keanu Reeves in The Matrix, bullet time sort of thing. Although subjectively you may think time slows down in stressful situations, that’s not really the case. Think about it: in, say, a car crash, do you hear people’s voices in slow motion?

This was actually demonstrated experimentally by David Eagleman and colleagues, who tossed volunteers backwards off a 45 metre tower. The subjects had devices strapped to their wrists that showed numbers alternating at varying rates. The hypothesis was that if people’s brains worked faster under stress then they would be able to read numbers oscillating at a quicker rate. (See Stetson C, Fiesta MP, Eagleman DM 2007, “Does time really slow down during a frightening event?”, PLoS ONE 2(12): e1295, doi:10.1371/journal.pone.0001295)

Volunteers in the time-slowing experiment had devices, called "perceptual chronometers", strapped to their wrists. They displayed alternating digits on their LED displays. When the digits alternated slowly they were easy to identify (a); but as they sped up, the numbers blurred into a uniform field (b). The people were then dropped backwards off a tower, into a safety net 31 m below (d).

What they found was that the experimental subjects – when they were able to actually concentrate on the watch – weren’t thinking any faster when falling then they were standing still. But afterwards, when they were asked to estimate the time of their fall, they recalled it as being at least a third longer than the time they guessed for other people falling.

The theory is that time seemed to move comparatively slower in their memory of the event because of the rapid rate of stimuli that their brains had to process in such a short time. This could go some way to explain how the years seem to go by faster and faster, because as you get older there are fewer new experiences.

Despite this, there are in fact ways you can train your brain to speed up and slow down beyond the 80 milliseconds. In another study, David Eagleman got people to push a button that made a light go on, but with a short delay (Stetson C, Cui X & Eagleman DM 2006, “Motor-sensory recalibration leads to an illusory reversal of action and sensation”, Neuron 51, pp. 651–659, DOI 10.1016/j.neuron.2006.08.006 [PDF 509 KB]).

As you’d expect, when the delay was less than 80 milliseconds, people thought the button-clicking and the light-lighting happened at the same time. But when the delay was consistently increased, the subjects’ internal chronometers could be recalibrated; they interpreted flashes up to 135 milliseconds later as being simultaneous with the click.

Then the researchers did something tricky: they suddenly decreased the delay to 44 milliseconds. When this happened, the people whose brains were recalibrated saw the flashes as coming before they pressed the button.

This breakdown in causality has led David Eagleman to the idea that schizophrenia may be a problem with perception of time. If, say, you were to “hear” yourself thinking something before your intention to think it, then it would seem like voices in your head coming from somewhere else. Or if you were to think about what you’re seeing on TV before your eyes register it, then it would seem like they’re broadcasting your thoughts. And indeed, in exercises with video games, Eagleman has found that schizophrenics have more difficulty recalibrating their brain clocks.

Tickling is a slightly more commonplace example. In 1998, scientists from University College in London showed that it was possible to tickle yourself by introducing a time delay (‎Blakemore S-J, Wolpert DM & Frith CD 1998, “Central cancellation of self-produced tickle sensation”, Nature Neuroscience vol. 1, no. 7, pp. 635-640 [PDF 271 KB]‎).

Machine used to tickle a person's palm with a small piece of soft foam. It can be operated either directly by the subject or, with a short delay, by an experimenter.

They did this by creating a mechanical tickle device that people could use to touch themselves. The greater the delay, the more tickly they found the touch. This is consistent with the notion that a disconnect between an impulse and an action makes them seem unrelated, or coming from someone else.

But as well as helping us to keep track of our own actions, the ability to connect cause and effect is the basis for our understanding of how the universe behaves in time. So you could argue that this 80 milliseconds of assembling data is essential for making sure we experience most things in the right order.

It’s curious that we puzzle over the unexpected physics of time – one of the most curious results of Einstein’s Special Relativity being that simultaneity isn’t the same for all observers – when our subjective definition of “now” is inherently fuzzy.

Can we really hope to understand the whole universe when we don’t truly understand how we experience it?

Burger myth is a load of rot

If you hang out on the internet much, you’ve probably come across video/photos/email similar to the following, in which a McDonald’s Happy Meal doesn’t appear to rot:

What does this mean? Are McDonald’s burgers made out of undigestible material, meaning you can eat as many as you want and not get fat? Or are they a miraculous, non-spoiling food source that could feed hungry millions in places without access to fresh produce or refrigeration?

Well, J. Kenji López-Alt of the Burger Lab has found a more mundane yet scientific answer, by comparing spoilage of a McDonald’s Quarter Pounder with a homemade control burger using good, honest, all-natural ingredients. Both burgers ended up with pretty much the same lack of mould or visible rot.

The main reason seems to be that the burgers in question are small enough to quickly dehydrate when left out on the kitchen bench. Together with the fact that the burger patties are essentially sterilised in the cooking process, they lack both starting mould spores and the environment in which to grow them.

This was further verified by sealing a McDonald’s burger in a plastic bag, which caused it to grow mould just like that loaf of supermarket bread you’ve left for too long.

The moral of the story? Don’t believe everything you see on the internet, at least not without thinking about what it actully means. And one demonstration on YouTube is not the same as a controlled experiment…

For the proper study, with control burgers and everything, head on over to the Burger Lab at Serious Eats.

Magnetic cows test their mettle

Birds do it, bees do it, even sharks in the seas do it… But can cows detect magnetic fields?

That question is, surprisingly, hotly debated. It all started in 2008 when Sabine Begall and colleagues from Germany and the Czech Republic found, using Google Earth, that cows tend to align themselves north-south along the Earth’s magnetic field (Begall S, Červený J, Neef J, Vojtěch O & Burda H 2008, “Magnetic alignment in grazing and resting cattle and deer”, Proceedings of the National Academy of Sciences, vol. 105, no. 36, pp. 13451-13455, doi:10.1073/pnas.0803650105).

It's actually rather difficult to find suitable herds of cattle on Google Maps, given that they're mostly found in rural areas where the photo resolution is poorer. The cows pictured here are near the 12 Apostles in Victoria, and don't have any obvious consistency in their alignment- the pattern was actually found in the statistics of 8,510 cows (click to embiggen).

The obvious question to ask is whether the alignment is due to environmental conditions. However, the researchers claimed they could rule this out: the behaviour of cattle under heat stress or when basking in the sun is well known, and not seen in the cows studied; also, the varying local wind patterns didn’t match the orientations (interestingly, although the wisdom accumulated by farmers over thousands of years was sufficient to rule out these environmental causes, no one had ever noticed the north-south alignment before).

For comparison, they also looked at “beds”, or body prints left in snow by red deer and roe deer. These were even more highly correlated along north-south alignment, and being created at night were clearly unrelated to the position of the sun. (Additionally, although the satellite photos of cows weren’t high enough resolution to see the actual direction they’re pointing, i.e. if it’s north or south, the deer beds showed that they face north when resting.)

Perhaps the clincher though is that at high latitudes, where there’s a big difference between magnetic and geographic north, the cows and deer were much more aligned to the magnetic.

So how do they do it? Is it because beef is so high in iron?

Actually, the mechanism that animals use to detect magnetic fields – a skill known as magnetoreception - is still largely unknown. But it has been studied more in some animals than others.

Birds, for instance, are known for their navigational abilities, and they have a few features sensitive to magnetic fields. They have a region in their upper beak that is known to contain magnetite (Fe₃O₄); also, their eyes use the light-sensitive protein cryptochrome, which is affected by magnetism, so they may be able to “see” magnetic fields.

We might even share this ability: human sinuses have been found to contain magnetite, and the cryptochrome in our eyes is also potentially magneto-sensitive (see Baker RR, Mather JG & Kennaugh JH 1983, “Magnetic bones in human sinuses”, Nature 301, pp. 78-80, doi:10.1038/301078a0 and Foley LE, Gegear RJ & Reppert SM 2011, “Human cryptochrome exhibits light-dependent magnetosensitivity”, Nature Communications 2, doi:10.1038/ncomms1364).

It’s actually with humans that the whole cow compass affair started: Sabine Begall had been studying naked mole rats, which always sleep on the south side of their burrows, and she got to wondering whether sleeping humans also had a preference.

Begall tried using Google Earth to examine campsites to see if there was a pattern, but it turned out to be very hard to see which way people were sleeping in tents. But cows were much more visible, and they indeed showed a pattern.

However, not everyone agrees. In January 2011 another Czech team did their own analysis of satellite photos of cows across Europe, and found no alignment (Hert J, Jelinek L, Pekarek L & Pavlicek A 2011, “No alignment of cattle along geomagnetic field lines found”, Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology, vol. 197, no. 6, pp. 677-682, doi:10.1007/s00359-011-0628-7).

But it doesn’t end there. In November, Begall’s team published a response, in which they re-analysed the same photos. They claim that the second study had used a different statistical technique and included a lot of “noise” in their data, including poor quality photos, pastures on slopes and herds near power lines, which supposedly disrupt the magnetic effect  (see Begall S, Burda H, Červený J, Gerter O, Neef-Weisse J & Němec P 2011, “Further support for the alignment of cattle along magnetic field lines: reply to Hert et al.” Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology, vol. 197, no. 12, pp. 1127-1133, doi:10.1007/s00359-011-0674-1).

So the great magnetic cow controversy rages on. But the original question is still unanswered: what about humans?

This is a topic waiting to be solved, perhaps with better quality satellite photos, or by choosing suitable locations: people lying on beach towels are much easier to see, but the beach is a possible confounding factor.

Or maybe like the deer, we need to examine campgrounds up close, or even just go down to the local park at lunchtime and see which way people are lying. It could be a fun summer research project!

Strigolactone, straight up

Plant growth is controlled by many different hormones (hormones being chemicals that influence the development and metabolism of both plants and animals). But recent research by the University of Queensland’s Dr Phil Brewer, among others, has shown that one hormone called strigolactone plays a number of important roles.

Striga asiatica or witchweed, a parasitic plant, the seeds of which germinate in the roots of their host when triggered by the hormone strigolactone - hence the name (image by Florida Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org, via Wikimedia Commons)

Firstly, in a paper published three years ago, Dr Brewer and colleagues showed that strigolactone inhibits the growth of side-branches, making plants instead grow straight up (Gomez-Roldan V, Fermas S, Brewer PB, Puech-Pagès V, Dun EA, Pillot J-P, Letisse F, Matusova R, Danoun S, Portais J-C, Bouwmeester H, Bécard G, Beveridge CA, Rameau C & Rochange SF 2008, “Strigolactone inhibition of shoot branching”, Nature, no. 455, pp. 189-194 doi:10.1038/nature07271).

Levels of strigolactone increase when light or nutrients are limited, which is a good time to grow taller than your neighbours, or to quickly reproduce before the food runs out (by inhibiting side-shoots, more energy is available for making flowers and seeds for reproduction).

Conversely, when nutrients are plentiful strigolactone levels fall, the plant grows bushy and is able to take advantage of its environment.

Now a follow up paper has revealed that strigolactone helps plants grow tall in another way: by making their stem thicker and stronger and so able to support the weight. It does this in response to signals issued by another hormone, auxin (Agusti J, Herolda S, Schwarz M, Pablo Sancheza, Ljung K, Dun EA, Brewer PB, Beveridge CA, Sieberer T, Sehr EM & Greb T, “Strigolactone signaling is required for auxin-dependent stimulation of secondary growth in plants”, Proceedings of the National Academy of Sciences, published online 28 November 2011, doi:10.1073/pnas.1111902108).

Strigolactone also seems to encourage growth in other areas too, like tiny hairs on the roots needed to extract nutrients from the soil and encourage the growth of symbiotic fungi.

Of course, like anything it comes with negative effects too: presence of strigolactone in the root systems seems to stimulate the germination of seeds of some parasitic weeds, like those of the genus Striga (from which strigolactone gets its name).

It could also be used by foresters to make plantation trees grow faster with straighter trunks, which probably counts as a positive for both us and the plants; until the whole chopping down thing, of course. Despite their signalling hormones, the trees are a little quiet about whether it’s good or bad overall.

Recently on the radio

We’ve been a bit quiet recently on the Lost in Science blog. But that doesn’t mean the team hasn’t been busy, oh no!

Here are some links to go with our recent radio broadcasts. Or, you can download the podcasts, for our shows from 3 November 2011 (25:54 min / 12 MB) and 10 November 2011 (28:09 min / 26 MB).

• Analysis of corporate ownership networks shows that out of 43,060 transnational companies, only 147 of them – mostly banks – control 40% of the wealth. Read more in New Scientist, or see the entire paper in the arXiv database.
• Protesting about this risks exposure to pepper spray, or Oleoresin Capsicum, which uses the chemical capsaicin ((CH₃)₂CHCH=CH(CH₂)₄CONHCH₂C₆H₃-4-(OH)-3-(OCH₃)), extracted from chilli peppers, to cause eye and skin irritation. Read about its health effects in Investigative Opthalmology and Visual Science and the North Carolina Medical Journal, or see treatment recommendations from Melbourne’s Royal Children’s Hospital.
• The Berkeley Earth Surface Temperature study, partly composed of and funded by climate change sceptics, has performed a massive re-analysis of global land temperature records and verified that yes, the world really is warming.
• Aside from being real, climate change seems to have caused Australian seaweed species to move between 50 and 200 km south, risking the habitat of many other species that depend on them. Read more at ABC Science, or see the paper in Current Biology.
• In more extinction news, Tasmanian devils are currently threatened by a contagious cancer, which seems to spread due to their genetic similarity. Hope is held for a small, genetically different and mostly disease-free population in the northwest of the state, research into which has won a team of scientists the 2011 Eureka Prize for Environmental Research (also see their paper in Conservation Biology). Although the recent discovery of devils with facial tumour disease in even that remote area has increased concern for this unique species.
• (A good friend of ours, John Cook of Skeptical Science, was also awarded the 2011 Eureka Prize for Advancement of Climate Change Knowledge. Congratulations John!)
• Speaking of genetic diversity, research on the Sandy Island mouse has shown that polygamous females produce more viable embryos. See the paper in Ecology Letters, or read more at the University of Western Australia.
• Finally, to space. Three recent discoveries have shed new light on how solar systems like ours form: there’s a planet called LkCa 15b, 473 light years away, which has been discovered in the process of forming; water seen in the planet-forming disk around the young star TW Hydrae (175 light years away) supports the theory that it collects around grains of dust to make comets, which then deposit the water on planets like Earth; and photos of the asteroid Lutetia, taken by the European Space Agency’s Rosetta probe, suggest that, at around 3.6 billion years old it’s a relic of the early Solar System, and have given clues to its formation.

Have you missed any other shows? Catch up on our old episodes!

Lost in science fiction: Evolution

With Halloween just around the corner, it’s as good an excuse as any to celebrate what we’re calling Lost in Science Fiction, aka science in the movies.

A great example is Evolution (2001), directed by Ivan Reitmann and starring David Duchovny, Julianne Moore, Orlando Jones and Seann William Scott (what’s he been doing lately?), a comedy named after the well-known biological process.

The title here is fairly accurate, since the movie does in fact depict alien organisms that rapidly evolve into new forms. However, that’s pretty much where the accuracy stops.

The film illustrates a misrepresentation often seen in science fiction films, the idea that evolution is directed and predetermined in some way. The alien creatures quickly evolve from simple forms into large, complex vertebrates, mimicking the development of life on Earth.

However, there is no pre-set “direction” of evolution, and definitely no pre-programmed outcome. Organisms evolve characteristics that enable them to survive and reproduce in their particular environment at their particular time, through the process of natural selection. So simple organisms can survive for a long time perfectly well: after all, we still have bacteria and microorganisms around today.

Of course, there is the process of convergent evolution, where unrelated organisms develop the same traits under similar environmental pressures. And in theory it could account for alien lifeforms evolving characteristics similar to those of their Earth counterparts.

But in the movie, the creatures largely evolve in a cave, so at best you could expect them to turn out like other cave-dwelling animals, or troglobites (congratulations, you just learnt a new word!).

So no, the movie Evolution, not so accurate. Nice try, Ivan Reitmann – although I’m sure we haven’t heard the last from you…

When purity doesn’t run deep

Tasmania is a great place, with vast areas of beautiful, unspoilt wilderness. And, just as some television commercials would have you believe, you’d expect the water there to be pure and unspoilt too.

Unfortunately, appearances can be deceiving. A microscopic parasite, Giardia duodenalis, is very common in Tasmanian waters. And it’s a major cause of diarrhea, or specifically, giardiasis.

Giardia is a genus of protozoa, single-celled organisms that live in animal digestive systems. Their life cycle goes through a couple of phases: the form that moves into and reproduces aexually in the small intestine is called the trophozoite. They’re also the ones that cause diarrhea, which moves the trophozoites into the large intestine where they form cysts, which are then excreted in faeces. These cysts make their way into the waterways, are again ingested by animals and, once they reach the stomach, release the trophozoites and start all over again.

The cysts are quite hardy, able to survive in the acidic environment of the stomach. They can also live for several months outside the body, performing better in colder water. Which is why they do so well in Tasmania, where they’re endemic in the animal population. A study published in 1998 found Giardia infection in 20% of dogs and cats, and up to 62% in native bandicoots.

Digitally-colourised, scanning electron micrograph of a Giardia protozoan from a rat’s intestine, showing the thread-like flagella that it uses to move (Image by Dr Stan Erlandsen and Dr Dennis Feely, Center for Disease Control, via Wikimedia Commons)

Fortunately, the fact that they prefer cold water means it’s fairly easy to avoid infection. Simply boiling the water kills the cysts, and any remaining trophozoites, making the water safe to drink.

Just don’t sip directly from a mountain stream, no matter how pure it appears.

Kettlewell JS, Bettiol SS, Davies N, Milstein T & Goldsmid JM 1998, “Epidemiology of giardiasis in Tasmania: a potential risk to residents and visitors”, Journal of Travel Medicine, vol. 5, no. 3, pp. 127-30 (PDF, 390 KB)

Weird sigh-ence

We’re all still on a high from the recent Aussie Nobel Prize win, but it’s important not to overlook those other prestigious annual science awards, the IgNobel Prizes.

The 2011 IgNobel Prizes include a couple of Australian winners: Robert Pietrzak, David Darby and Paul Maruff shared the Medicine Prize with other international researchers for studying how needing to wee affects your concentration (see their article in Neurourology and Urodynamics); and Darryl Gwynne and David Rentz took out the Biology Prize for showing that male Buprestid beetles mistake beer bottles for female beetles (and see their article in the Australian Journal of Entomology).

Male Bupestrid beetle attempting to mate with a beer bottle (Photo by Gwynne and Rentz)

There were many other worthy winners, but one that particularly caught my eye was the Psychology Prize, awarded to Norwegian psychologist Karl Halvor Teigen for his work trying to understand why people sigh (Karl Halvor Teigen 2008, “Is a sigh ‘just a sigh’? Sighs as emotional signals and responses to a difficult task”, Scandinavian Journal of Psychology, vol. 49, no. 1, pp. 49–57).

Using a series of questionnaires and practical exercise, what he found was that, although most of us think of sighs as an expression of sadness, they’re actually more associated with a feeling of resignation, like giving up on a frustrating task.

Teigen performed this study to demonstrate to his students that not all questions have been answered. But curiously, since his work was published other researchers have also studied the cause of sighs, only from a physiological perspective (Vlemincxa E, Van Diesta I, Lehrerb PM, Aubertc AE, Van den Bergh O 2010, “Respiratory variability preceding and following sighs: A resetter hypothesis”, Biological Psychology, vol. 84, no. 1, pp. 82-87).

Using a very different method, Vlemincxa et al. got remarkably similar results. After a sequence of irregular breathing – also often associated with a stressful task – the experimental subjects sighed and returned to a more regular breathing pattern. Their hypothesis is that we sigh to “reset” our breathing after stress.

Think about this next time you, or someone else, sighs, and see if it agrees with these studies. And reflect on how right Karl Halvor Teigen really was: it’s still possible to find things in every day life, that we all do, but we don’t fully understand.

Nitrogen cycle to the moon

The discovery of bacteria that can turn urine into rocket fuel has, unsurprisingly, gotten a lot of media attention in recent weeks. But despite the slight exaggeration – NASA has given up the idea of flying to Mars on wee power any time soon – it’s actually a key component in a mechanism essential to supporting life in the ocean.

Nitrogen is an essential part of biology, making up substances like amino acids and DNA. However, despite the fact that it makes up 78% of the Earth’s atmosphere, its gaseous form, N₂, is mostly inert and hard for plants and animals to use.

As a result, we rely on a complex series of chemical reactions, known as the nitrogen cycle, in which N₂ is “fixed” by bacteria or chemical processes into a form we can use; and then, when we’ve finished with it, either through waste or decomposition, it’s turned back into nitrogen gas.

It’s this second part where the rocket fuel comes in: the nitrogen-containing waste product that comes from decomposition, or particularly, urine, is ammonium, NH₄. In the deep oceans, where naturally there is no air, ammonium is turned back into N₂ by a reaction called anaerobic ammonium oxidation, or anammox for short.

Marine nitrogen cycle, showing the role of anammox in turning ammonium into N2 in the deeper anoxic region (without oxygen). PON stands for "particulate organic nitrogen", which includes phytoplankton; DON is "dissolved organic nitrogen"; and DNRA is, wait for it, "dissimilatory nitrate reductase to ammonium" (Image from Nature)

In a letter recently published in the journal Nature, scientists from Radboud University Nijmegen in the Netherlands have described the chemical mechanism used by bacteria that perform this anammox reaction. And an important part of it involves the chemical hydrazine, N₂H₄. And hydrazine happens to be a very unstable compound used in rocket fuel.

As I mentioned earlier, NASA has dismissed this as a way to travel to other planets using astronaut wee. But this is still a useful discovery, apart from the fact that it explains the production of 50% of the N₂ released from the oceans.

Being anaerobic (that is, not needing oxygen), this reaction is useful for treating human waste. And potentially it means we could create other useful biofuels from sewage treatment.

Which might not quite be rocket fuel, but it’s nothing to piss on.

Kartal B, Maalcke WJ, de Almeida NM, Cirpus I, Gloerich J, Geerts W, Op den Camp HJ, Harhangi HR, Janssen-Megens EM, Francoijs K-J, Stunnenberg HG, Keltjens JT, Jetten MSM & Strous M 2011, “Molecular mechanism of anaerobic ammonium oxidation”, Nature, published online 02 October 2011, doi:10.1038/nature10453

Glow cats looking for the cure

Cats are stealthy animals, sneaking around at night hunting prey, so glowing in the dark might not seem terribly useful. But if it protects them from cat AIDS, maybe it’s not such a bad thing.

OK, so we’re not talking about ordinary cats. These are transgenic cats, genetically modified organisms that were given a gene from rhesus macaque monkeys that blocks infection by the feline immunodeficiency virus (FIV), a close relative of HIV.

They were also given a jellyfish gene that causes them to glow under ultraviolet light. This makes a handy marker to distinguish cats that are carrying altered genes from those that aren’t.

A transgenic kitten, seen here glowing under ultraviolet light. It's accompanied by a regular, non-fluorescent, control cat (Image from Mayo Clinic)

The big success was that when the cats reproduced, the new genes were passed on to their offspring, creating glow-in-the-dark, FIV-resistant kittens.

Although the technique used to create these fluorescent felines can’t actually be used to treat infected humans or cats, it does point the way for medical – and veterinary – researchers to develop possible gene therapies.

References:

• Wongsrikeao P, Saenz D, Rinkoski T, Otoi T & Poeschla E 2011, “Antiviral restriction factor transgenesis in the domestic cat”, Nature Methods, no. 8, pp. 853–859 (doi:10.1038/nmeth.1703)
• Mayo Clinic teams with glowing cats against AIDS, other diseases.