Our Changing World

Thursday 30 October 2014, with Alison Ballance, Ruth Beran & Veronika Meduna

On This Programme

Killing Rats With Self Setting Traps

By Alison Ballance

A ship rat is easily identifiable from a Norway rat: it has a longer tail, which reaches past the animal's nose, and large ears that fold down over the eyes. Rat teeth marks on a detector card (right) are quite long, and as well, rats quite often destroy the card.

A ship rat is easily identifiable from a Norway rat: it has a longer tail, which reaches past the animal's nose, and large ears that fold down over the eyes. Rat teeth marks on a detector card (right) are quite long, and as well, rats quite often destroy the card.

Photo: RNZ / Alison Ballance

The Good Nature company has designed a range of humane, self resetting animal traps to control pest species such as rats, stoats and possums. A few years ago on Our Changing World we featured the self resetting possum trap, and to find out how the trap development has gone since then Alison Ballance catches up with Robbie Greig again, to see their rat trap in action.

A number of the self setting rat traps have been placed along Wellington’s South Coast to help protect nesting little penguins, as part of Forest and Bird’s Places for Penguins project.

Robbie Greig from Good Nature, next to a self resetting rat trap screwed onto a small tree trunk, and holding a ship rat killed in the trap.

Robbie Greig from Good Nature, next to a self resetting rat trap screwed onto a small tree trunk, and holding a ship rat killed in the trap.

Photo: RNZ / Alison Ballance

The rat trap is mounted above the ground, on a tree trunk, and a smell lure encourages the rodent to stick its head into the trap. It features a small carbon dioxide cylinder which fires a bolt when the animal brushes past a leaf trigger. The bolt is fired into the rat’s head, killing it instantly, and the body drops onto the ground beneath the trap. The canister can kill 20 rats or mice before it needs to be replaced. Alternatively it should be replaced every 6 months.

The key to the trap is the bait. Robbie Greig says that for rats and mice they use a nut-based lure. The same trap can be used for stoats, in which case a meat-based lure is used, as well as for animals overseas such as mongooses, in which case a fish-based lure is used. At the moment the bait needs to be refreshed every month, as it oxidises in contact with air and becomes less effective.

“The bait is the crux at the moment,” says Robbie. “We’re working on systems so that you’ll have a bait that you install, that will constantly dispatch a high protein high sugar bait, and that will last you six months.”

Good Nature have also developed some simple detector cards, containing a small packet of the nut-based lure. This is screwed onto a trunk, and left for a few days. Animals that interfere with the card will leave distinctive teeth marks – and in the case of rats, will often destroy the entire card. The detector cards serves three purposes: it identifies which species are present, where the animals are and therefore where is a good site to place a trap, and it also acts to pre-feed the animal and get it used to eating the nut-based lure. Then, when a trap is put in place the rat is already primed to the bait.

Mice tooth marks on a detector card (left) are very small and tidy, whereas possum teeth marks are very long.

Mice tooth marks on a detector card (left) are very small and tidy, whereas possum teeth marks are very long.

Photo: RNZ / Alison Ballance

The Good Nature team have been working with the Department of Conservation to eradicate rats from small Native Island, close to Stewart Island. Native Island is within swimming distance of rats, so the idea is that the resetting traps that are used to eliminate the existing population will remain in place to catch any new arrivals.

The self setting traps are another tool in the fight against introduced predators, that sit alongside toxins such as 1080 and brodifacoum which are applied aerially for large scale control, as well as single kill traps that require frequent checking.


Protein Nano-LEGO

By Ruth Beran

“We are really interested in making things smaller these days,” says PhD student Amy Yewdall from the University of Canterbury. “And we’re thinking of proteins as a nanomaterial that we can use as building blocks for future machines, so you’ve got nanomachines that we can make, or biosensors.”

In particular, Amy is working with proteins called peroxiredoxins that form “exciting structures”. These proteins are ring-shaped and self-assemble to form stacks or tubes.

A picture of Amy Yewdall and flasks of bacteria growing proteins

Amy Yewdall and flasks of bacteria growing proteins

Photo: RNZ / Ruth Beran

“What I’m really interested in is looking at proteins with diverse structures so I can create big novel structures out of them, so think of them like nano LEGOs. I can try and fit these protein units together to make cool structures,” she says.

And they’re tiny. The rings they form are about 15 nanometres big. “Maybe 400 billion of these can fit on the top of a pin,” says Amy.

According to Amy, there are many potential future applications for these proteins that could be realised in the future. “If we can have tubes, say, we can maybe functionalise these tubes by creating nanowires," she says. "So if we can stick metal ions onto the inner surface of my tubes perhaps we can create conductible nanowires that can also be biocompatible."

These structures would be a similar size to carbon nanotubes, but are easier to generate, require less energy (so are cheaper to produce) and are potentially biocompatible, so could be used in medicine.

To create these stackable rings, Amy starts with DNA because it can be used as a program or code for the proteins that are produced from it. She uses circular DNA, or plasmids, which can be ordered commercially “Once we have these DNAs we can put them inside bacteria,” she says. “You can kind of think of them like workhorses, to produce proteins.”

Every living thing produces protein, from humans to plants, fungus to bacteria. “We choose bacteria because they’re really easy to grow and they’re quite simple creatures. So you put in the DNA and you just let it do its thing,” says Amy.

The bacteria can be used like machines or biofactories to make these proteins, which are grown in 2 litre flasks in a temperature controlled room of 26˚C. “Once we put the DNAs into the bacteria, we let the bacteria grow up a huge amount of this protein,” says Amy. "Then we break up the cells and extract this protein from the rest of the other stuff, like all the cellular walls and all the other proteins, and we purify it by using their special properties.” These special properties could be size, surface charge, or by beads which attach to an artificial tag on the protein.

Because the proteins are so small, they are incredible hard to see. Most of the time, what Amy deals with looks like water. So one way to “see” them is by manipulating light, and images need to be taken using an electron microscope.

Two electron microscope images showing rings (left) and rings stacked to form a tube (right)

Two electron microscope images showing rings (left) and rings stacked to form a tube (right)

Photo: Amy Yewdall / University of Canterbury

Recently, it’s been discovered that pH can be used as a switch to create bigger structures out of these protein rings. Lowering the pH, or increasing the acidity, of the protein’s environment changes its surface charge, causing them to stick together and form longer tubes or stacks of rings. Making the surroundings more alkaline, causes the stacks to fall apart and go back into separate rings.

The next step for Amy is protein engineering. “I would like to add different units onto the outside of my proteins. So artificial units that can attach to different things,” says Amy.  And she’s thinking potentially clickable units that glow, to show that these proteins are really versatile building blocks that can be used in nanotechnology.


Detecting Oestrogen in the Environment

By Alison Ballance

Left to right: Shalen Kumar, Ken McNatty, Justin Hodgkiss and Omar Alsager.

Left to right: Shalen Kumar, Ken McNatty, Justin Hodgkiss and Omar Alsager.

Photo: RNZ / Alison Ballance

A team of researchers at Victoria University of Wellington have developed a novel sensor that can detect tiny amounts of the hormone oestrogen in environmental samples.

Ken McNatty from the School of Biological Sciences is interested in ways of detecting environmental contaminants. “Currently we don’t have sensitive methods of detecting environmental contaminants, so my interest was trying to develop new techniques for detecting trace residues, particularly of organic materials, plasticisers, hormones [and oestrogen mimics] that are in the environment, and being able to monitor them continuously over a long period of time,” says Ken McNatty. “I was interested in developing systems that would be ten to a thousand–fold more sensitive than any current method.”

Ken and PhD student Shalen Kumar have been focusing their efforts on developing a PCR-based detection system, but in the meantime Shalen’s work on aptamers has led to the development of a different kind of sensor.

Aptamers are single-stranded DNA or RNA molecules that can bind to pre-selected targets including proteins and peptides. They bind tightly and are very specific to particular molecules. Shalen’s work identified an aptamer that detected oestrogen. The idea of aptamers piqued the interest of Justin Hodgkiss from the School of Chemical and Physical Sciences, and the MacDiarmid Institute for Advanced Materials and Nanotechnology.

“When I first learnt about apatmers I thought that was so cool the way you could use synthetic chemistry and biology to discover these sequences that stick really strongly to something,” says Justin. “Obviously these things are exactly what you need to make a sensor, as a sensor needs something that sticks to the target you’re interested in, the hormone oestrogen in our case.”

The oestrogen sensor operates with a simple colur change. The pink solution, at left, contains an aptamer that has bound to gold nanoparticles. In the purple solution, at right, the aptamer has detected oestrogen

The oestrogen sensor operates with a simple colur change. The pink solution, at left, contains an aptamer that has bound to gold nanoparticles. In the purple solution, at right, the aptamer has detected oestrogen

Photo: RNZ / Alison Ballance

PhD student Omar Alsager explains that “our sensor is a combination of the [oestrogen-specific] aptamer that Shalen has developed and gold nano-particles.”

“The aptamer coats the surface of gold nano-particles, which are pink in colour,” says Justin. “When this solution is exposed to oestrogen the aptamer binds to it and the solution changes to a purple colour.”

“The amounts I’m talking about are really tiny. The equivalent would be taking a pinch of oestrogen and putting it in an Olympic swimming pool.

The sensor is very specific to the hormone oestrogen, and doesn’t react to other hormones such as testosterone, and it works in ‘messy’ solutions such as human urine as well as cleaner water samples.

The research has just been published in the jounral Biosensors and Bioelectronics, and the team are carrying on to refine the sensitivity of the sensor and to expand it to target other molecules. Justin is excited by the possibilities that aptamers offer in future sensor development.

“In principle you can make an aptamer for any protein or molecule you want,” says Justin. “And Shalen has the methods to do that really effectively.”

Ken McNatty says the sensor is a great first step, although he’s still hoping to develop a much more sensitive PCR-based system.

Earlier this year Our Changing World spoke with ex-pat Kiwi chemist Terry Collins about his research with green chemistry and oestrogen mimics.

Justin Hodgkiss has previously featured on Our Changing World talking about printable solar cells.

Next Thursday 6 November, at 7.30pm in Palmerston North, Ken will be talking about how his reproductive research has led to improved success rates in IVF - in a Royal Society of New Zealand Ten By Ten lecture titled ‘What makes a good egg’.


SOS for Soils

Photo: RNZ / Veronika Meduna

By Veronika Meduna Veronika.Meduna@radionz.co.nz

To many of us, soil is just a bit of dirt. We overlook it, take it for granted – yet we need soil as much as we need the air we breathe. Without soil there is no life.

Next year is the International Year of Soils, and the aim of the UN-sponsored campaign is to raise awareness of the crucial role soil plays in food security and by providing essential ecosystem services such as nutrient storage and water filtration.

Why do we need a global view on soils? Here’s what Australian soil scientist Neil McKenzie says:  

Thousands of years ago if we degraded our landscape, we starved. The reality now is that with more than half of us living in cities, our environmental impact is scattered all around the planet, and understanding how that impact plays out is important for all countries – because the scattered evidence at the moment is that we are reaching critical limits.

Soil scientists worldwide are working to make all of us appreciate soil more and to realise that fertile soil is a finite resource. Back in the 1960s, 0.4 hectares of arable land was available per person, but today this has dropped to half of that area and by 2050, it is expected to be just 0.1 hectares per person.

Neil McKenzie is a member of the Intergovernmental Technical Panel on Soils, which was established last year in response to a call for a globally coordinated effort to collate information about soils. The basic challenge, he says, is that we need to increase food production by about 50 to 70 per cent by 2050 to feed a growing population. “But we have to do that with very limited extra land, so any land that we lose will create a strong price signal, and any increase in price volatility sends millions of people into poverty.”

He says in New Zealand and Australia, we are and will remain food secure, but as exporting nations with a focus on primary production “our impact on the global food system is significant and that’s why we have to think hard about maintaining food production and sustainable soils”.

With more than half the world's population living in cities, people are becoming more detached from food production.

With more than half the world's population living in cities, people are becoming more detached from food production.

Photo: RNZ / Veronika Meduna

Last week, soil scientists gathered in Wellington to launch a Pacific branch of the Global Soil Partnership, an initiative by the UN’s Food and Agriculture Organisation. Massey University soil scientist Marta Camps says soils are under pressure for many reasons, including unsustainable land management, erosion and urban expansion. While urbanisation is a major issue in more densely populated parts of the world, the Pacific region also loses significant areas of fertile land as cities grow and rural areas expand.

One of the projects already underway is the Global Soil Map, which uses digital technology to map soils and to help predict soil properties at fine resolution. “We have an enormous legacy of soil information,” says Mike Grundy from CSIRO. “It was mostly collected pre-computers and models, so we have a messy collage of historic information which is not easily usable for the things we need to do. The exciting thing about this project is that we can now specify what information we need and then get the best estimate everywhere in world.”

With the help of satellite data, the project will create a global and dynamic map which will show changes in soil properties over time and to run future scenarios to help make “smarter decisions about how we produce our food”.

Soil properties are driven by a range of environmental factors, including the amount of biomass, the terrain and the way that water moves across the surface, the geology and the way rivers have moved sediment around – and also what people have done on top of it. _ Mike Grundy

Landcare Research scientist Pierre Roudier says the project tracks 10 key soil attributes, for example pH levels and carbon content, which provide baseline data from which other information can be drawn. “This can then be applied to planning how cities like Auckland, for example, should develop.”

The Intergovernmental Technical Panel on Soils will release its first assessment of global soils on World Soil Day (December 5) in 2015.

 


OCW Opening Theme - Mystery Sound 18

The Our Changing World opening theme is made up of 18 sounds that appeared on the show during 2012 and 2013. The 18th – and final - mystery sound is a spray can, spraying aniseed smell around at possum trap as part of a story about eradicating possums on Otago Peninsula.

Pest-free Otago Peninsula ( 13 min 18 sec )


Spineless Wonder of the Year

Photo: Alison Ballance; Landcare Research

Spring seems the perfect season to treasure our invertebrates – let us know which of them should become the first Spineless Wonder of the Year.

Photo: Andy Reisinger; Alison Ballance

Conservation Week

Conservation Week 2014 runs from 1-9 November, and this year’s theme is 'discover the world where you live’.

Seabird of the Year Competition

This year Forest and Bird is running a Seabird of the Year competition, instead of the usual Bird of the Year competition, from 3-24 November.

Here are some great seabird stories from our audio archive.

Alison Ballance bands Gibson’s wandering albatrosses, and hears from Kath Walker and Graeme Elliott how populations of the two New Zealand wandering albatross species have declined by 50% in the last 10 years.

Dragonfly Science talk about analysing fisheries by-catch data and what it shows.

Young royal albatrosses from Taiaroa Head near Dunedin ‘text home’ to tell researchers their location.

The Hutton’s Shearwater Trust has been translocating Hutton’s shearwater chicks from the main colony high in the mountains of the Seaward Kaikouras down to the Kaikoura Peninsula, and Alison Ballance joins a chick-collecting trip.

Veronika Meduna joins the West Coast Blue Penguin Trust and hears how people and their cars are the little penguins' biggest threat.

Alison Ballance heads to Matiu-Somes Island in Wellington harbour to see how a group of volunteers are feeding fluttering shearwater chicks to help establish a new population.

There is a thriving population of little blue penguins on Matiu-Somes Island, as Alison Ballance discovers when she joins a long term monitoring project.

Sooty shearwaters are long distance fliers, and nest on islands around New Zealand, including Mana Island.

Colin Miskelly has been involved in seabird translocations to Mana Island, and Alison Ballance joins him to check up on some of the birds.

Coming Up - Thursday 6 November

We mark Conservation Week and the Seabird of the Year competition with stories about yellow-eyed penguins and the Trojan Female pest control idea, the winners of the inaugural Conservation Innovation Awards, and a 3D virtual reality house to help stroke victims with their memory.