Friday, October 14, 2011

Quorum Sensing: Wellcome Trust science writing prize & The Cockroach Catcher

Wellcome Trust science writing prize: 2011

Bacteria and the power of teamwork

How do simple bugs thrive? It's all about quorum-sensing. Tess Shellard, in her winning essay for the Wellcome Trust Science Writing Prize, explains

Bacteria play a crucial role in life on this planet. They digest our food, synthesise our vitamins, help to make our wine and cheese.
Others are deadly, the cause of numerous diseases. But how have these single-celled organisms taken charge when they have no ears to hear, no sense of touch and no central intelligence to organise their assault? Their secret lies in teamwork. Each bacterium can secrete a chemical that can be read only by members of the same species; the concentration of this chemical can tell it how many of its siblings are nearby. This ability, called quorum-sensing, helps the bacteria to time how and when they express their genes. They don't just act; they wait until there are enough of them for the action to be effective and co-ordinate their moves.
Not only can a bacterium tell if kin are near, it can tell if it is among different types of bacteria, allowing it to build alliances that can help them all to thrive.
Professor Bonnie Bassler of Princeton University's department of molecular biology has led the research on quorum-sensing. She found that the Hawaiian bobtail squid hunts safely at night thanks to the quorum-sensing abilities of a bacterium called Vibrio fischeri. By day, the squids bury themselves in the sand, coming out at night to hunt in the shallows. But they cast a shadow in the moonlit waters, which can leave them vulnerable to predators. Enter the Vibrio fischeri. These live in a sac in the squids' mantles and, when there are enough of them, they switch on a light. Their bioluminescence disguises the squid's silhouette on the sea bed. To get it just right, sensors on the squid's back gauge the strength of moonlight, with filters adjusting the light emitted from the sacs.

In return for all this handy illumination, the bacteria are kept well-fed. In the morning, the squid purges itself of its visitors and, as the bacteria's numbers drop below the quorum threshold, they turn off their light. The remaining population then do what they do best and multiply throughout the day, reaching sufficient numbers by nightfall to start glowing all over again.
The inaugural Wellcome Trust science writing prize, in association with the Guardian and the Observer, was judged by: Alan Rusbridger, editor-in-chief of Guardian News & Media; Robin McKie, science editor of the Observer; Sir Mark Walport, director of the Wellcome Trust; Clare Matterson, director of medical humanities and engagement at the Wellcome Trust; and Dara O Briain, broadcaster and comedian.

Very Interesting!!!

My own Quorum Sensing posts: since early 2008. Did any medical student read it as one of them could have won the prize!!!

Feb 07, 2008

There is a chapter in The Cockroach Catcher called “SARS, Freedom and Knowledge”. I wrote about the SARS virus:
“For the first time, doctors and nurses who were normally in the forefront of the fight against diseases were fighting for survival from SARS (Severe Acute Respiratory Syndrome), a new and dangerously contagious disease. ……
Our knowledge base was in total chaos. What we knew was obviously not good enough. Nor were the most up to date antiviral drugs……”
I am not a bacteriologist nor virologist but that did not stop me writing about these little creatures. 
When I picked up the in-flight magazine on a recent flight, an article titled “Genius at Work” caught my eye. Bonnie Bassler is the bacteriologist at Princeton who discovered and pioneered the work on what she now called quorum sensing in microbes. To be more precise her initial work was with Vibrio harveyi. Vibrio is in the family of bacteria that causes Cholera. Vibrio vulnificus is carried by oysters and was most likely responsible for the serious illness of Michael Winner, film producer and now food writer of the London Sunday Times.
On following this up back home, I found an article on the website of Howard Hughes Medical Institute – she is one of the HHMI Investigators. From this article, I learned that:
“Virulent bacteria do not want to begin secreting toxins too soon, or the host's immune system will quickly eliminate the nascent infection. Instead, Bassler explained, using quorum sensing, the bacteria count themselves and when they reach a sufficiently high number, they all launch their attack simultaneously. This way, the bacteria are more likely to overpower the immune system….
For the past three hundred years……we’ve been completely wrong……we don’t know anything about bacteria until about a decade ago….”
Wow! Just as we thought we knew everything there is to know about microbes.
Bonnie Bassler will one day get the Nobel prize for medicine. You read it here first.
Fascinated, I wanted to find out more about this genius. I would like to share with you her answers to some of questions that children were invited to ask about her life and work:
“You all asked me essentially the same question: how and when did I get interested in science. As a kid, I loved doing puzzles, solving riddles, and reading mystery books. I also loved animals and always had pets. Around high school, those interests (puzzle solving and animals) convinced me that I should be a veterinarian so I could work on mysterious illnesses in animals and cure them. In college, I realized I did not like big-bloody stuff. It became clear to me that I probably wouldn't enjoy being a vet, but I did not know what I'd do instead. 
Fortunately, the vet curriculum required me to take biochemistry, genetics, and lab courses. Once I got into those classes, I fell in love with doing puzzles about little things (DNA and RNA and proteins and how they all fit together in cells). I also adored doing lab experiments and puzzling over my results. I realized that lab research was the perfect path for me. It allowed me to spend every day figuring out mysteries/puzzles that have to do with what make us alive. What could be a bigger mystery or puzzle? I changed my major in my junior year, and I have not left the lab since. (I still love animals and have a pet—Spark my cat—and I often go hiking hoping to see animals in the wild.)
I think being open-minded about what Nature is trying to tell you is the key to being creative and successful.”

Now in England, only a couple of Medical Schools require biology. In my book, I puzzled over this fact:
“The ability to dissect out a full set of cockroach salivary glands was a prerequisite requirement for medical school entrance in Hong Kong in our days. It is almost a 180 degree turn around nowadays when many young doctors have no idea about the biological world we live in. Nearly all Medical Schools in England no longer specify biology as a prerequisite subject for anybody who wishes to embark on the study of the human body. As we are so intertwined with the rest of the living biological world I find this policy quite extraordinary.”

Aug 23, 2008
Nearly 15 years since the discovery of Quorum Sensing by Nottingham University the topic seemed to be shrouded in some mystery. The Cockroach Catcher read about it by chance in an airline magazine and his own survey of some recent ...

Oct 24, 2010
Vibrio cholerae, like many other bacteria, uses quorum sensing to synchronize gene expression on a population-wide level. Upon infection of its human host, V. cholerae immediately initiates expression of virulence genes ...

May 27, 2011
Instead, Bassler explained, using quorum sensing, the bacteria count themselves and when they reach a sufficiently high number, they all launch their attack simultaneously. This way, the bacteria are more likely to overpower ...

Jun 22, 2011
Guys & Dr House: Quorum Sensing & MRSA. Looks like Dr House is on leave. Surgeon David Nunn reprimanding the TV crew and officials who accompanied. David Cameron and Nick Clegg on their visit to Guy's on 14 June. ...

Cockroaches & Superbugs

Nottingham Quorum Sensing : Latest QS research papers

·                                 Cockroachcatcher
14 October 2011 5:35PM
My blog The Cockroach Catcher Blog started writing about Quorum Sensing in 2008. It has to be noted that our own Nottingham University had an important role and of course Bassler. My latest blog included all my posts:
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·                                 Imonlysaying
14 October 2011 9:29PM
I saw Bassler talk at The last EMBO Meeting...captivating stuff, especially for someone whose research never touched on anything of the kind. (Apart from unknowingly using quorum sensing to induce expression of useful proteins in bacteria... only to purify said proteins and discard the bactera - sorry bacteria!) I wrote a blog post about it, nothing spectacular but a little bit more technical:
The blog above by Cockroachcatcher from 2008 is also really interesting and gives more background so read that if you haven't already!
Finally, congratulations to Tess Shellard for her winning article...Great lay science writing on a great topic.

1 comment:

Anonymous said...

I read the Guardian article and I think your posts gave a lot of scientific detail making it very interesting.