Our Changing World
Thursday 17 July 2014, with Alison Ballance, Ruth Beran & Veronika Meduna
Audio from Thursday 17 July 2014
Not all audio is available due to copyright restrictions.
High Altitude Training ( 13′ 23″ )
21:06 Exercise scientists simulate high altitude by removing oxygen from air, and then study the physiological effects of low oxygen levels on athletes as well as sedentary people
Sensing Gravity in Bones ( 15′ 8″ )
21:20 A genetic condition which causes very dense bones is being studied to try and work out the mechanism that sense gravity in bones
Green Chemistry ( 11′ 15″ )
21:34 Ex-pat Kiwi chemist Terry Collins has been designing small enzyme mimics that are able to remove chemicals and hormones from water
Fish and Warming Oceans ( 14′ 51″ )
21:46 University of Auckland research finds that heart function in fish is an indicator of which species may cope better with rising ocean temperatures.
OCW Mystery Sound 3 ( 32″ )
21:56 The third sound from Our Changing World's 2014-5 opening theme
Our Changing World Theme ( 43″ )
21:58 This is the opening theme for Our Changing World for 2014-5. It is made up of 17 sounds from previous programmes
On This Programme
A 15-year research programme at Lincoln University’s Exercise Science Lab has shown that altitude training produces measurable improvements in the performance of elite athletes, but for ordinary people the researchers say that altitude training is no substitute for exercise.
While some athletes head to high altitude for hypoxia training, others choose to train in the lab.
‘We don’t have many mountains that are high enough to do altitude training so we use simulated altitude,’ says Associate Professor of Exercise and Sports Science Mike Hamlin. ‘We take you to altitude by dropping your oxygen levels.’
At sea level air contains about 21% oxygen, whereas at about 4000 metres above sea level the proportion of oxygen is just 12-13%. Mike uses a machine called a hypoxicator to control the amount of air delivered to someone through a mask, and the subjects receive intermittent hypoxic exposure, which alternates 5 minutes of low oxygen exposure with 5 minutes of room air over 60-90 minutes.
When someone is exposed to low oxygen levels the oxygen saturation levels in their blood immediately drop (the blue line on the graph at left). Their body immediately responds by increasing the rate of breathing, to bring more air into the lungs, and by increasing the heart rate in an attempt to supply enough oxygen through the body (red line at left). The graph (left) shows a typical response during intermittent hypoxic exposure, with oxygen saturation and heart rate returning to normal levels when the person breathes normal air.
Over a longer time frame the kidneys respond by producing a hormone known as erythropoietin or EPO. EPO is responsible for making the marrow in the body’s long bones produce more red blood cells, as the haemoglobin in red blood cells is responsible for carrying oxygen around the body. EPO also leads to an increased blood volume. There are also changes within cells in the way mitochondria use oxygen, an increase in the number and size of capillaries in muscle, changes to muscle metabolism, and changes to the buffering capacity of the body so it can withstand a lower, more acidic pH for longer. It is these longer term physiological changes that athletes hope to stimulate by undergoing hypoxia training in an effort to improve their physical performance, and is why human EPO is also used as an illegal performance enhancing drug.
Mike told Our Changing World producer Alison Ballance that ‘what we’re doing with athletes is we’re giving them two stressors. We’re giving them the hypoxia but also the exercise, and the theory there is they’ll adapt a lot better – a lot more and a lot faster – and we have shown it does seem to work with athletes. Exercising under hypoxia does give you beneficial results.’
‘Our first instinct was if we can get people a little more tolerant to exercise maybe they’ll exercise more and that’ll improve their cardiovascular risk profile’ says Catherine.
While Catherine carried out three studies which showed that there did appear to be some benefits such as lowered systolic blood pressure she says that ‘the key message that we found is that exercise is really good for you, so if you can exercise you really should.’
‘The altitude training helped but it also took a lot of time, so if you’re sedentary and want to improve your cardiovascular health, just go and exercise.’
A recent paper published in the 3 July 2014 edition of Nature has revealed an interesting evolutionary twist to how Tibetans have adapted to live at high altitude. While haemoglobin levels in most people rise when they visit high altitudes, Tibetans only increase their haemoglobin levels a limited amount, as too much haemoglobin in the blood can lead to a greater risk of heart disease. The new research traced a pattern of mutations in the gene EPAS1, which regulates haemoglobin, and suggests that the ancestors of modern Tibetans inherited their variant of EPAS1 either from the now extinct Denisovans or their relatives.
Sensing the Force of Gravity in Bones
“Bones which are regularly loaded and exercised get stronger, and bones which aren’t exercised – maybe if you’re on bed rest or in a wheelchair or an astronaut in space -- get weaker,” says University of Otago PhD student Emma Wade.
While this phenomenon is well known, the molecular mechanisms of how the force of gravity, is sensed in bone is not known, and this is something that Emma (pictured left) and her supervisor Professor Stephen Robertson (pictured right) are looking into.
“We think filamin is part of this, we think it not only protects your cells from the day to day movement that your skeleton does, but also somehow signals to the cell that that movement is happening and tells it to turn on pathways to make more bone,” says Emma.
Filamin A is a protein with a hinge that allows it to flex and bend. It's basically a cellular spring. Emma is looking at patients with a condition called frontometaphyseal dysplasia who have very dense bones, implying that the force sensing mechanism in their bones has gone wrong. These patients have mutations in the gene that encodes for filamin A.
Emma is looking at the skin cells of patients with this condition, as well a mouse model, to try and determine how the force-sensing mechanism works. This would not only help patients and their families, understand how the condition works, but in the future may lead to some form of therapy for people who are bed-ridden, or wheelchair bound, or astronauts in space.
“Plus, finding filamin A’s role in the skeleton is really useful for downstream therapies skeletal conditions like osteoporosis which are big conditions affecting the whole world really,” says Emma.
Ex-pat Kiwi chemist Professor Terry Collins has been involved in the field of green chemistry since the early 1980s, and he’s hopeful that tiny catalysts that he’s designed will be a big help in removing chemicals, hormones and hormone-mimics from wastewater.
‘Green chemistry is really about designing chemical products and processes that reduce and eliminate hazardous substances. Basically, to get rid of toxic substances from the commercial space.’
Terry, who is the Teresa Heinz Professor of Green Chemistry at Carnegie Mellon University in the United States told Alison Ballance that the aim of his research was ‘to produce small molecules that would do what big enzymes do because small molecules are much easier to commercialise so that you could disinfect water with hydrogen peroxide rather than chlorine, to avoid chlorination disinfection by-products.’
Terry’s research, which began in the early 1980s, has developed ‘TAML Activators’, a new class of oxidation catalysts, which activate hydrogen peroxide to destroy chemicals in water.
Humans alive today have thousands more chemical compounds in their urine than their grandparents did. In a recent study Canadian researchers detected at least 3,079 compounds in urine. While 72 of these compounds are made by bacteria, and 1,453 come from the body itself, a further 2,282 come from diet, drugs, cosmetics or environmental exposure. Some of these anthropogenic chemicals are ingested deliberately, such as pharmaceuticals, while others, such as plasticisers, are by-products from common household items such as plastic bottles.
Of particular concern to Terry are endocrine disruptors, which affect human hormones and can have feminising or masculinising effects on humans and wildlife.
‘A very tiny amount of the catalyst in the water with hydrogen peroxide will break these endocrine disrupting compounds down very quickly’, says Terry ‘and it looks like it will be much more cost-effective and less energy intensive.’
Terry says the critical question for him was whether his catalysts might, in their turn become a problem, and so the catalysts have been subjected to – and passed – a number of tests to ensure they aren’t themselves endocrine disruptors.
Fish and Warming Oceans
Ocean temperatures are predicted to rise by 1-3ºC by the end of this century, and new research at the University of Auckland suggests that this may bring some fish species close to their physiological limit.
Tony Hickey (pictured on the left, catching spotties with student Julia MacDonald) and Fathima Iftikar, both lecturers in biological sciences, have exposed three species of wrasse from different environments – tropical, temperate and cold – to gradually rising water temperatures. In a study published in the journal PLOS ONE this week, they found that the heart was the first organ to fail as the fish experienced heat stress.
Most fish are cold-blooded, or ectotherms, and their body temperature is the same as that of their environment. As the water temperature rises, the fish warm up and their metabolism speeds up.
'What we predicted was that if the fish were from cold water, we couldn’t heat them up very much before they started having troubles. If they were acclimated to warmer temperatures, you could heat them up more than the 15-degree fish. The truth was that they were very much the same and they all struggled to be taken up hotter.'
The team kept the three fish species in tanks at temperatures of their normal environment and then warmed the water gradually, by about one degree per week. They monitored the heart beat with a device similar to what midwives use to listen to the heart of babies in the womb.
Tony Hickey told Our Changing World producer Veronika Meduna that the Australian tropical species Thalassoma lunare, commonly known as moon wrasse, had the narrowest thermal range and fared worse than any species in the study. "When we went to a tropical fish it was just two or tree degrees more, so they had very little scope. This research shows that the heart acts as a ‘bio-indicator’ of which species may survive rises in ocean temperature."
The study, funded through the Marsden Fund and involving Canadian and Australian researchers, found that mitochondria (power units within heart cells called) begin to fail as temperatures rise.
'The tropical wrasse could only tolerate a shift of a few degrees before experiencing changes to their mitochondria, and this resulted in a loss of efficiency so that even though the fish could acclimatise to some degree, it came at a cost.'
The life-sustaining mitochondria began to fail in all three species before full heart failure occurred, suggesting that mitochondrial failure is the most likely cause of heart failure in heat-stressed animals. The team says that changes in temperature may limit the range of environments fish can occupy. "Understanding mitochondrial function, or dysfunction, in ectotherms such as fish has important ramifications in terms of climate change and requires more study to investigate the capacity of a wide range of species to survive ocean warming."
OCW Opening Theme – Mystery Sound 3
Every two years we create a new opening theme for Our Changing World, using sounds that have appeared in stories during the previous two years. This year’s theme comprises 17 different sounds, and the third mystery sound is a stoat trap going off, from a story about eradicating stoats from Resolution Island in Fiordland.
Royal Society of New Zealand ‘Ten by Ten’ lecture – Superconductors
Jeff Tallon, Principal Scientist at the Robinson Research Institute at Victoria University of Wellington, will be delivering the next lecture in the 2014 Ten by Ten lecture series in Auckland at 6pm on Thursday 24 July. His talk is titled powering the Future and he will be talking about his research into high-temperature superconductors. You can book a free ticket here.
This is the second year that the Royal Society of New Zealand has run the Ten by Ten lectures, and this year Marsden Fund researchers are talking about their work and its impact on society.
Jeff Tallon and his colleague Bob Buckley received the 2010 Prime Minister's Science Prize for their work on superconductors.
Coming Up – Thursday 24 July 2014
Pre-election science special, memory research, and the Flora Finder app that helps you identify native plants.