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Stuart West, who recently joined Oxford's Department of Zoology, has just published in Current Biology about his research into how bacteria cells interact.

I asked Stuart about what bacteria working together or cheating each other means for infection in humans:

OxSciBlog: What are the social interactions that go on between bacterial cells?
Stuart West: Bacteria cooperate to perform a wide range of functions. They secrete a number of factors out of the cell that then provide benefits to the local group - for example to scavenge nutrients, aid movement, overcome their host, kill and degrade prey, kill competitors and degrade antibiotics. They join together to form 'slime cities' (biofilms). Many of these behaviours are controlled by a social signalling system that has been termed 'quorum sensing' and which appears to switch on cooperative behaviours when they are most beneficial, which is when population densities are high.

OSB: How do these interactions affect the overall virulence of an infection?
SW: Hugely. These cooperative behaviours are crucial to the growth of bacteria and the damage that they do to their host. Indeed, many of these traits are also termed 'virulence factors'.

OSB: What is 'quorum sensing' and why is it important to understand it?
SW: Quorum sensing (QS) is the process where bacteria use small molecules diffusable molecules as signals which control other behaviours. The signal molecules are secreted out of the cell, and can then be taken up by the same cell or other cells nearby. This uptake has two effects.

First, it stimulates the production of many products that are released out into the environment, and which are 'public goods' that benefit the local bacteria. Second, it leads to an increase in production of the signalling molecules themselves. At high cell densities this leads to a positive feedback that markedly increases the production of factors released by the cell. The idea here is that QS turns on the production of these extracellular public goods when it is most useful to do so: at high densities.

From a pure science perspective, QS is interesting, because signalling and communication can be hard to explain from an evolutionary perspective, because they are exploitable by individuals that lie and cheat. From an applied perspective, QS is fundamental to the success and virulence of pathogenic bacteria.

OSB: How might your findings help in the search for new ways to combat infection?
SW: One way is that cheats that do not perform cooperative behaviours such as QS could be introduced into hosts to outcompete wild-type cooperators. As well as directly reducing virulence, this could drive down the bacterial population size, which may benefit other intervention strategies such as treatment with antibiotics. Another way is that other beneficial traits, such as antibiotic susceptibility, could also be hitch-hiked into infections by such cheats who do not perform QS or other social behaviours.

Stuart West is Professor of Evolutionary Biology at Oxford's Department of Zoology.

I really enjoyed this article in New Scientist about Lagrangian points - 'dead zones' in the solar system where opposing forces cancel out gravity and all kinds of items from cosmic dust to asteroids may accumulate becalmed.

NASA's twin STEREO probes, that were launched in 2006 to observe the Sun, are now being tasked to spy on two of these enigmatic spaces on the way to their final destinations (one orbiting ahead of the Earth and the other in its wake).

It's a great example of the serendipitous component to a lot of science: as one of the STEREO lead researchers explains the probes were never designed to look for asteroids (they're actually looking for solar storms) but now they have a golden opportunity to go rock-spotting.

I think the role of serendipity, especially in areas such as space and big science facilities where project lead times are so long, is something that doesn't get talked about enough. It's part of the invisible web that joins up different areas of science and ensures that a new instrument or technical advance in one area can create spin-off benefits for research into something very different. 

There's a nice Oxford link to STEREO that I'll be blogging about in detail later in the year. 

Today saw the launch of Galaxy Zoo 2: the project that enables web users to contribute to research into galaxies and how they evolve.

This report from BBC Breakfast's Graham Satchell gives an excellent overview of the project and includes an interview with one of Galaxy Zoo's founders, Oxford's Chris Lintott as well as just a few of the galaxy-spotting volunteers [nicknamed 'Zooites'] who have helped make the project such a success.

First reports are that GZ2's servers are buzzing with ten times the traffic of the original GZ launch: no doubt helped by the fact that Graham's report is linked from the front page of the entire BBC website! Chris's appearance on The Today Programme this morning can't have hurt either. 

Galactic mergers - cosmic 'train wrecks' in which galaxies collide - are one of the things that the GZ2 team hope users visiting the site can help them describe in detail. One of the discussions we had whilst putting the release together was whether mergers could be described as 'odd' or 'unusual' - although there was agreement that they are rare. 

Interestingly, as part of looking into this, I stumbled across this New Scientist piece that reports on research into how, in less than two billion years, our own galaxy - the Milky Way - will in fact merge with our neighbour the Andromeda galaxy: these two galaxies are currently rushing towards each other at 120 kilometres per second.

New Scientist's Hazel Muir writes: 'The scientists watched how gravity choreographed the motions of the two galaxies up to 10 billion years into the future. The results suggest they will pass close to each other in less than 2 billion years, well within the Sun's lifetime. At this point, their mutual gravity would start to mess up their structures and tug out long tails of stars and gas.'

'The two galaxies would then overshoot and come together again for a second close passage before finally merging about 5 billion years from now. The merged galaxy, which [the researcher] dubs Milkomeda, will be a blobby elliptical galaxy, rather than a neat spiral like Andromeda or the Milky Way today.'

Perhaps we should all visit GZ2 to find out what a merger looks like, just in case we're around in two billion years' time to watch... 

All this week we're celebrating Darwin and the advances in evolutionary theory that have built upon his work.

From The Beagle to the beard Charles Darwin and his world seem rather distant from our lives today: little wonder perhaps, as so much has changed in 200 years.

But how does Darwin match up to the 21st Century scientist? This is one of the intriguing questions Paul Harvey of Oxford's Department of Zoology addresses in an article to appear in the Journal of Biology.

He argues that Darwin posed many of the same sorts of questions as  biologists working today. 'He set the research agenda that many still follow: as Dobzhansky famously put it “nothing in Biology makes sense except in the light of evolution”.'

As Paul comments he could not have known how to pursue the great unknowns in genetics, or how developmental biology would be incorporated into mainstream evolutionary theory 'But he did frame many of the unsolved questions for what we would now call organismic biology.'

'He appreciated the importance of sexual selection, that something generally kept sex ratios around 50:50, that altruism must evolve by some interesting process, that distastefulness and warning colouration are in some sense adaptations. He didn't exactly know how these things evolved, and even explicitly left some problems to be solved in the future.'

Darwin may have needed others to come up with the elegant algebra to identify what would evolve as conditions changed 'But, as a 21st Century scientist, his correspondents would have included some theoreticians who could better develop his ideas and force him to state his assumptions with greater clarity.'

In other ways, however, Darwin was a scientist of his time: who, in a more gentlemanly age of scientific reporting which did not give so much weight to publishing first, was determined to reflect at length and not rush out his results.

'Indeed, he went further and argued that his career had taught him that there had not been an example when he has regretted holding back on publication,' Paul notes. 'The published product, he argued, was all the better for repeated polishing and tinkering. That is virtually unthinkable nowadays, with so many Wallace orthologues in the woodwork. The balance has shifted increasingly towards achieving priority.'

Here was a scientist who got better with age or perhaps whose thought processes hardly seemed to age at all: 'there's no doubt in my mind that he could have kept on going for another lifetime - once you have set the conceptual foundation as he did, then the world opens up for you... We have to remind ourselves that, while Darwin was always learning, if he felt that a gradual accumulation of facts questioned a treasured conclusion, then he would revisit that conclusion and all that resulted from it.'

Professor Paul Harvey is Head of Oxford's Department of Zoology.

Read more of our Darwin special: worms & vertebrates, humanity's roots, birds, beaks & species, virus wars

All this week we're celebrating Darwin and the advances in evolutionary theory that have built upon his work.

I asked Aris Katzourakis of Oxford's Department of Zoology about the evolutionary 'arms race' between viruses and us:

OxSciBlog: How does studying virus evolution compare to studying the evolution of larger organisms?
Aris Katzourakis: Virus evolution occurs over far shorter time frames, and can be observed on the molecular level. For example, for rapidly evolving RNA viruses like HIV or Hepatitis C, evolution can be observed during the course of an infection within a single patient, while for the Influenza virus, evolution can be observed within the human population over the years. This offers unique opportunities to study evolution in real time, while also enabling predictions about the course of viral evolution that can be applied in a public health setting.

OSB: What makes the evolution of viruses such as lentiviruses and HIV/AIDS so challenging to unravel?
AK: The lentiviruses are locked in an arms race with the immune systems of their hosts, meaning that both parties are constantly changing in order to adapt to new challenges. This effect has been called the ‘Red Queen’ effect in evolutionary biology, in reference to the statement by the character of the same new, from Lewis Carroll's book - “It takes all the running you can do, to keep in the same place”. In practical terms, this means that the genomes of lentiviruses are constantly changing, and we are still a long way from unravelling all the pressures exerted upon the virus by the immune systems of their mammalian hosts.

OSB: What does research into lentiviruses suggest about their possible future evolution and that of HIV/AIDS?
AK: Recent research from studies of endogenous lentiviruses has shown that the lentiviruses are far older and more widespread among mammals than has been previously appreciated. This implies that there may be more lentiviruses that remain undiscovered in the wild, that could potentially make the leap from infecting other mammals to infecting people. Furthermore, the realization that lentiviruses are millions of years old implies that the corresponding conflict with their hosts immune systems has been played out over this period of time. Perhaps there remain undiscovered host innate immune factors in mammalian species, resulting from this ancient conflict, that could be harnessed in the fight against HIV.

OSB: What technological advances on the horizon could transform studies of virus evolution?
AK: Ever cheaper and more rapid sequencing will undoubtedly greatly expand our knowledge of virus evolution. Coupled with this, advances in computational techniques required to make sense of this data will prove instrumental. Many exciting discoveries in virology have occurred from the most unexpected places - I suspect the most important findings of the coming years will come as a surprise to researchers in the field of virus evolution.

Dr Aris Katzourakis is based at the Department of Zoology and the Institute for Emergent Infections, James Martin 21st Century School.

Read more of our Darwin special: worms & vertebrates, humanity's roots, birds, beaks & species