Our Changing World
Thursday 23 October 2014, with Alison Ballance, Ruth Beran & Veronika Meduna
On This Programme
- 3D Bioprinting Body Parts
- Celebrating Young Science Orators
- Science Behind 1080 Use in Conservation
- OCW Opening Theme - Mystery Sound 17
3D Bioprinting Body Parts
By Ruth Beran
The 3D bioprinter at the University of Otago, Christchurch is a metre high, a metre wide, and has a lamina flow system attached to the top of it, so it’s also sterile.
“If we want to try and manufacture scaffolds, but in particular print with patient’s cells, that process has to remain sterile - like any other cell culture we would do in the lab,” says senior research fellow Dr Tim Woodfield.
In the future, the 3D bioprinter will be used to create materials or tissues that are implanted into the body to replace or regenerate damaged tissue, such as cartilage or bone. So instead of a metal hip implant, a person could have a biocompatible, 3D printed implant which uses their own cells.
Like any other colour printer, the 3D bioprinter has cartridges or print heads. Some cartridges have degradable, biocompatible polymer materials, which are heated up, melted and extruded out. “A bit like toothpaste,” says Tim.
Other cartridges use hydrogels, which are like jelly. They are gelatine based, have a high water content, and can contain cells which are kept at body temperature.
“So the gelatine is denatured collagen, so it is a naturally-derived material,” says postdoctoral fellow Khoon Lim. “It has been previously shown to support a lot of cell proliferation and promote tissue formation.”
“So we’re trying to put the cells in an environment where they are most happy,” says Tim.
However, gels are structurally quite weak, but with some clever chemistry, they can be combined with the printed synthetic polymers which form the structural component.
“A real sort of scaffolding, like around a building, where they provide a temporary support,” says Tim.
Shining UV light onto the hydrogels cross-links them. “Once it’s cross-linked, it’s kind of like set in concrete,” says Tim.
So gels are put into the print heads, printed between the fibres as the structure is created, and the UV light is shone on later to solidify it.
The cells themselves are grown in a tissue culture lab. For example, chondrocytes, or cartilage cells are taken out of patients and then grown up in a 3D environment to create 1mm tissue spheres or clusters of cells. “Those spheroids are a collection of about 250,000 cells,” says Tim.
Then, like little LEGO blocks, the spheres can be added together. “In almost a high throughput way we can use these as little modules, or little tissue building blocks, to assemble a much more complex tissue,” says Tim, “that’s why we also need the automated capability of our 3D printing.”
Printing is done layer by layer, and models of patient’s body parts, like their knee, can be taken from a CT or MRI image, and software can instruct the printer to print complex shapes made of multiple materials.
“And the 3D printer also allows us to make the shapes that we want and to make it bigger as well,” says postdoctoral fellow Ben Schon. “That’s really important, especially if you want to put it in a person eventually.”
The scaffold used in the 3D printing also determines how strong the implant is. “So by tailoring how we’re controlling the lay down of each of these fibres…we can make something that is really, really stiff or we could make something that’s really, really soft,” says Tim.
In the future, it is envisaged that this technology will be located in, or close to, surgery. However, there are some limitations before body parts could be printed for operations. Firstly, although imaging could be done prior to surgery to design the implant, another preliminary surgery would need to happen beforehand to harvest the patient’s own tissue so the cells can be grown and expanded for the printing process. Also, the regulatory framework is quite complicated and would need to be to be considered before commercial applications.
“We’re aware of some of those challenges, and trying to come up with ways where we might be able to get around some of those levels of complexity. It requires quite a bit of development and further testing,” says Tim.
Celebrating Young Science Orators
By Veronika Meduna Veronika.Meduna@radionz.co.nz
The late Sir Paul Callaghan wanted New Zealand to be ‘the most beautiful, stimulating, and exciting place in the world in which to live and work.’
As part of an effort to encourage young scientists to be part of this vision he approached the Rotary Club of Wellington to organise a competition that has been named in his honour – the Eureka Sir Paul Callaghan awards for young science orators.
Now in its third year, 2014 was the first time that regional competitions were held to select 12 finalists who then went on to give their presentations at a national symposium. In a 12-minute speech, each student had to demonstrate knowledge of an area of science, present it clearly to a non-science audience, and set out its practical application and relevance to New Zealand.
The premier award went to University of Otago neuroscience student, Sam Hall-McMaster, for his presentation on the potential value of nanotechnology for New Zealand, economically, socially and environmentally. He was interviewed on Saturday Morning with Kim Hill.
Sam Hall-McMaster: Eureka and nanotechnology ( 9 min 42 sec )
In this feature, four of the finalists present their ideas. Correspondence School student Siska Falconer raises the issue of antibiotic resistance, which you can also read about in her blog about the evolution of superbugs; University of Waikato engineering student Rochelle Molina discusses how fish scales could be used to produce new biodegradable plastics; St. Patricks College student Jack Wynne explores the future of quantum computers; and Grant McNaughton from Logan Park High School argues that scientific literacy should be as important as reading and writing.
Science Behind 1080 Use in Conservation
By Alison Ballance
“If you go into a forest anywhere in New Zealand, that hasn’t had any pest control, the thing that strikes you about it is that it’s incredibly quiet – because our forest are buggered. The predators have been gobbling their way through our forest birds for the last 100 years. And if we’re killing any birds with 1080, it’s more than made up for by the increased productivity that these birds have because we’ve killed the rats, stoats and possums that eat them, particularly while they’re nesting.” – Graeme Elliott, scientist, Department of Conservation
In July this year, then-Conservation Minister Nick Smith announced that Battle for our Birds, billed as New Zealand’s largest-ever pest control programme, would go ahead to protect native wildlife from a plague of rats and stoats.
The $21-million programme is using aerial drops of the toxin 1080 across 700,000 hectares of Department of Conservation land, to knock back rodent and stoat numbers, which have surged following a mass seeding event in native beech forests.
In June 2011 Parliamentary Commissioner for the Environment Jan Wright published as report titled ‘Evaluating the use of 1080: Predators, poisons and silent forests.’ In the report she noted: ‘It was a surprise in this investigation to discover that possums, rats and stoats are only controlled on one eighth of Department of Conservation land. We may well be looking at a future where many of our special plants and animals can be found only on offshore islands with extremely limited access to the public and in sanctuaries behind big fences. Without active pest management, kiwi chicks have a one-in-twenty chance of making it to adulthood.’
Jan Wright also noted in her report: ‘It is my view based on careful analysis of the evidence that not only should the use of 1080 continue (including in aerial operations) to protect our forests, but that we should use more of it.’ Battle for our Birds is a response to this call.
Battle for our Birds began its programme of aerial drops in August, and they will continue at different sites across the country until the end of the year. Results from Waikaia Forest in Southland, which was one of the first areas to be treated, has seen rat abundance, as measured in tracking tunnels drop, from above 30% and rising, to 0.5%, while mouse tracking rates are just 3%. DoC describes this as a fantastic result. Rats, stoats and mice are monitored using tracking tunnels, and possums are monitored using wax tags
1080 was developed as a vertebrate pesticide in the United States during the 1940s, and at the same time this research was being carried out scientists in Western Australia identified the same compound in nature, in plants that are toxic to livestock. The earliest report of field testing of 1080 in New Zealand was 1956.
To find out more about the science of 1080, Alison Ballance spoke with a toxicologist, a native bird ecologist and a Department of Conservation biodiversity manager.
To see a long-term research project into the impact of predators on native bird populations in action and the effectiveness of 1080 treatment, Alison headed to South Westland, to join DoC’s Jason Malham as he remotely collected data from a female kaka carrying a smart diagnostic radio transmitter. Jason is part of a team, led by conservation scientist Graeme Elliott, carrying out long term ecological research in South Westland, the Marlborough Sounds and the Tararua Range near Wellington. Remote sound recorders are used to record native forest abundance throughout the year. As well, the nesting success of some species is followed in detail: in South Westland the species are kaka, morepork and rifleman. At Tennyson Inlet in the Marlborough Sounds the species are robins, weka and rifleman, and in the Tararuas rifleman are studied in detail.
This project began about 6 years ago and will continue for another year or two. The areas were chosen as they were already being treated with 1080 for conservation, with the aim of killing, rats, mice, stoats and possums. At each site there is a control area which is not treated with 1080, and one or treatment sites receiving different amounts of 1080 at different intervals. Large amounts of data has been collected and data analysis is ongoing, but initial results show that mice and rat numbers drop to almost undetectable levels straight after a poison bait drop, that robin breeding success climbs from 20% to 80% following a bait drop, and that birds such as kaka are eight times more abundant in areas treated with 1080 than in areas that haven’t been treated. Fifty moreporks were fitted with radio transmitters before 1080 operations and all survived.
The Tongariro Conservation Area in the central North Island is a national kiwi sanctuary and one of five national security sites for whio or blue duck. Brent Guy is Biodiversity Conservation Services Manager for DoC, and he says that the 17,000 hectare area has been treated with 1080 to control predators and protect kiwi and whio since the late 1990s. A new regime of treatment will see much smaller amounts of toxic baits applied aerially every 3 years rather 5 years, as monitoring has shown that kiwi chick survival is high in the two years following 1080 treatment, but declines rapidly in the third year as predator numbers rebuild. In recognition of the importance of the Tongariro Conservation Area to the local community for hunting, a large area of the forest was treated with 1080 baits that had had deer repellent added.
A week before an aerial 1080 operation, non toxic baits are dropped. This provides a pre-feed to rats, and ensures a high rat kill following the toxic bait drop. Mice, rats and possums eat baits directly, while stoats are secondarily killed after eating rats and mice that have died from the poison.
Landcare Research toxicologist Penny Fisher says that among the advantages of 1080 or sodium fluoracetate compared to other toxins is that it is a simple organic molecule, it is well-known, it is cheap, it is water soluble and it biodegrades quickly and easily. It is rapidly broken down by microbes in the soil, and if an animal consumes a sub-lethal dose the 1080 is rapidly excreted in urine within a few days. In the body sodium fluoroacetate breaks down to fluorocitrate, which interferes with the Kreb’s cycle in cells. If an animal consumes a lethal dose it dies within 24 hours.
The toxicology lab at Landcare Research is able to detect amounts of 1080 in water as small as 0.1 part per billion. The allowable level of 1080 in water is 2 parts per billion. According to this website: 'Landcare Research maintains a database of the results of over 2000 water samples tested by the toxicology laboratory for 1080 contamination since 1990. As summarised by Booth et al. (2007), 3.6% (76) of the water samples contained detectable 1080 residues and in most of them (70) the 1080 concentration measured was less than 1ng/mL (parts per billion). There is no evidence that drinking water has been contaminated and the extensive research and monitoring in catchments treated with 1080 indicates that this is highly improbable if current safety procedures are followed.'
The Forest and Bird website reports that: 'By comparison,1080 occurs naturally in black tea leaves from India and Sri Lanka - brewing a normal cuppa will give you about 5ppb of 1080 in your tea, which is 1.5 times the drinking water limit.’
Following recent media coverage about the results of a laboratory test in which captive trout were force fed high doses of 1080 and subsequently tested positive for low levels of 1080 in their flesh, the Ministry of Primary Industries has issued advice that ‘trout caught from areas following 1080 pest control operations do not pose a food safety risk to anglers.’
OCW Opening Theme - Mystery Sound 17
The Our Changing World opening theme is made up of 18 sounds that appeared on the show during 2012 and 2013. The 17th mystery sound is honeybees buzzing, from a story about the state of bees in New Zealand.
Honeybees ( 14 min 58 sec )
Blogs from Antipodes Island
Alison Ballance is currently on Antipodes Island, the most remote of New Zealand’s subantarctic islands. She is taking part in a Department of Conservation expedition as part of the lead-up to the mouse eradication planned for winter 2015. There are three builders on the trip who are fixing the hut, which was badly damaged by a large mud slip in January this year. There is also a botanist, and a team of people counting erect-crested penguins, banding Antipodean wandering albatross chicks, and checking out pipits and parakeets. The mouse eradication is funded by DoC and the Million Dollar Mouse project, which raised funds from the public to match a large donation by the Morgan Foundation. Alison is sending back blogs (when technology and time permits!) and you can check these, along with blogs from an earlier expedition which managed to get building materials ashore, on the Million Dollar Mouse website.
Coming Up - Thursday 30 October
Self setting rat traps, a novel oestrogen detector, nanobiotechnology and an SOS for soils.