The genetics of germs

Nell:: The first story we're looking at is looking at the placebo effect which is this idea that patients can get a benefit even when they're not actually being treated with anything. And they're looking at the genes that could possibly contribute to this. So, this is published in PLoS ONE and the researchers have looked at a particular gene that has a role in regulating the dopamine levels in the brain. So this is to do with our kind of reward and pleasure responses to things.

Kat:: It's like the happy chemical, isn't it? It makes you feel good, all that kind of stuff.

Nell:: Exactly and the idea, their sort of hypothesis at the beginning was that perhaps people who can produce more dopamine in their brain, so they can have more of this sort of pleasure response to specific things, maybe they could be more susceptible to the placebo effect, and they wanted to test this. So they did that by getting some patients who have IBS, irritable bowel syndrome, and looking at different types of treatment. So, that ranged from them being on a waiting list and getting no treatment at all, or they could have a placebo acupuncture which is an interesting concept.

Kat:: I wonder how that works. They just stick them or something?

Nell: Yeah, it's a sham acupuncture device. So probably, you can feel it, but they're not actually going through the acupuncture procedures or they got the acupuncture placebo treatment so fake acupuncture, plus to getting talked to really nice, friendly, supportive doctor who listen to their concerns. And they compared all those different things and found that people with this genetic change that meant they could produce more dopamine, responded a lot better to the supportive doctor and the placebo acupuncture, so it's quite interesting.

Kat:: I think this is fascinating because it's interesting that they chose IBS which is a condition that it's quite chronic, it's difficult to know what causes it, it's difficult to know how you treat it. And it seems to me that many of the conditions that respond to alternative treatments, complementary treatments that are considered by many to be placebos are these kind of very chronic diseases. I wonder if it would work for other things, just people would be more susceptible to having a nice hot bath or going shopping?

Nell:: It is really interesting because the placebo effect is really powerful and it really can help make people feel a lot better even when we're looking at really serious diseases. So, if we can find a way to sort of harness that, figure out who could benefit most, how can we use the placebo effect to our own ends. That would really be exciting. It's a small study, but it's sort of pointing us in a direction of you know, what's happening in the brain, how could this affect how you respond to the placebo effect.

Kat:: And speaking of things evolving, there's some worrying news about koalas I saw this month. This is very sad news. What's going on here?

Nell:: So, this is something we're hearing more and more about which is a bit of a shame. So koalas obviously are not doing particularly well in the wild because of various things. They've been hunted, they've had problems with disease, and this were some researchers going back to see whether old koala bones, examples that we have in museums for example, whether they had more genetic diversity than koalas today, and their idea was that, back when there were many more koalas around, there'd be a lot more diversity in the genes that all the animals had. And what they found is that actually, koalas have had quite low genetic diversity for over a century, over 120 years. And it is a real shame because it's meaning that it's getting harder and harder for them to cope with what the environment is throwing at them, things like Chlamydia for example. It sounds really weird, but koalas are actually really badly affected by Chlamydia.

Kat:: Really? That sounds so sad.

内尔::我发现了这个在澳大利亚tralia because I just went to look at all the cool animals. We went to a place called Kangaroo Island which is a big island right at the bottom of Australia where they've got a great wildlife sanctuary set up. It was really nice to be there, but we were looking at a koala and this guy just saying, "Oh, it's really great because the koalas here don't have chlamydia." And I was just standing there going, "What?"

Kat:: Eww!

Nell:: Koalas with sexually transmitted diseases, it's really bizarre. But actually, loads of koalas on the mainland have chlamydia and it kills them. We think that perhaps the fact that they've got this low genetic diversity means that there's not much resistance in the population and they're not doing very well at sort of evolving to cope with this.

Kat:: It's sad that you think the populations, when they get so small, there really isn't a lot of hope for them. I hope there is hope for koalas.

Nelly:: Yeah, exactly because I mean, I guess the question would be, where do you get extra genetic diversity from? Once it's gone, it's gone which is a real shame. So I mean hopefully, we can find ways to cope with this and I guess the main thing for researchers would be, this is a lesson for how you deal with animals that could get to that point. We have to stop that from happening.

Kat:: Well, let's keep our fingers crossed for the koala bears. Thanks very much, Nell.

南佛罗里达大学的研究人员甲型肝炎e tracked down a genetic change linked to old-age hearing loss - something that affects many millions of people around the world every year - publishing their findings in the journal Hearing Research. Thanks to a 9-year-long study of nearly 700 people, the scientists discovered that a certain variationS in a gene called GRM7, short for glutamate receptor metabotropic 7, were linked to a higher risk of hearing loss later in life - the first time a gene has been linked to old-age hearing loss. GRM7 helps to convert the sounds we hear into nerve signals that go to the brain, where they're decoded and interpreted.

The researchers suggest that it might be possible one day to test people for the presence of the risky gene variations, so they could choose to take extra precautions to protect their hearing if they wished.

Kat:: But now, it's time to take a closer look at bacterial genes. I spoke to Dr Matt Holden at the Sanger Institute in Cambridge to find out how advances in genome sequencing are helping researchers and doctors to understand more about bad bacteria, and even to track infections as they happen.

马特::基因组测序在过去说,15个是的rs of about bacterial sequencing has been very informative about having this amount of contents of a genome, and it's really propelled research forward. It allowed biologists and geneticists to have a glimpse of what the genetic blue prints of many important pathogens are and from that, try and dissect what are the important genes, what are the genes that allow it to survive in certain niches, what are the genes that maybe cause a damage when they're causing disease. In this case, we're now moving to a situation with sequencing where the technological advances of sequencing mean that rather than being a fundamental sort of research tool, which is sort of based in institutions like the Sanger Institute where I work and university labs, it's now been sort of transited to the sort of setting of a diagnostic lab because of the reduction in cost and increase in throughput.

所以,我们现在看作为di基因组测序agnostic tool, so when you are identifying a bacteria, you won't just identify them by maybe culturing them on a selected media. You'll actually sequence the genome. So, for a pathogen that's been isolated from a disease situation, you can identify or reconstruct the genome and identify what genes it's carrying which can be very important when you're trying to provide information about what antibiotics to use because from the genome, you can predict what antibiotics the pathogen may be sensitive for. The key to this is, it can be done very cheaply or is certainly becoming cheaper and also, it can be done rapidly which means it can certainly provide clinicians and those involved in the management of disease, important information within a very short space of time.

Kat:: One of the things that you did recently was to actually track an infection, an MRSA infection. How did you go about doing that and what did you find?

Matt:: What we wanted to do was to use genome sequencing to look at the isolates that were identified in this outbreak that occurred on a neonatal intensive care ward and to see what information genome sequencing will provide that would help combat this sort of transmission in the future. So, we were also interested to discover what it told us about the outbreak itself or perhaps standard clinical diagnostics and infection control didn't. So we sequenced the genomes of 14 isolates that were identified as outbreak and also, additional isolates of MRSA that were identified in the hospital at the same time. And showed through genome sequencing, that we were able to effectively reconstruct a family tree for these bacteria.

所以,我们能做的就是确定克丽rly which bacteria are involved in the outbreak and showed that these were very distinct from the other bacteria that were floating around in the hospital at that time. But we're also were able to go into the genomes and predict what antibiotics the microorganisms were sensitive to. So, providing information that clinicians could potentially use very quickly to treat patients who are becoming infected and also, predict which toxins they were carrying which again, can be important to inform clinicians as to how to manage disease when it occurs in a clinical setting where you have potentially pathogenic bacteria that have got important toxins involved that can cause particular types of disease.

Kat:: How do you think being able to track the genetics of bacteria in this way will be useful to doctors and beneficial to patients in the future?

Matt:: Well obviously, the study we've done recently is very much a sort of proof of principle and so, it's a case where we're seeing what the potential of it is. Obviously, with technology changes, with technology progress, the cost of sequencing will go down and also, the rapidity with which you can sequence the genome is going to go up. So, the immediate benefit will be hopefully that you will be able to identify what bacteria is associated with infection, and whether or not it's related to other bacteria that part of an outbreak very rapidly, hopefully quicker than standard techniques. And also, with the decreasing cost, you can do it more cheaply.

The other benefit is you have the entire genome sequence there, so you can actually look at all the contents and provide all this additional information that we currently don't have. We get these extra resolution and be able to distinguish related bacteria, but we also get all the genetic information and it gives us a new insight to what the bacteria are carrying.

Kat:: That was Dr Matt Holden from the Wellcome Trust Sanger Institute.