Marsden Fund Newsletter No 16 July 2001 Contents Smart surfactants Weta throw light on the mechanics of evolution Marsden news Putting water distribution under the microscope Rock sponges - "living fossils" Banking on price stability Comparing the floras and vegetation of New Zealand and the Andes Smart surfactants Professor Paul Callaghan, FRS, FRSNZ. Ever stopped to think about the science behind dishwashing? Detergent (surfactant) molecules each have a hydrophilic (water-loving) "head" and a hydrophobic "tail", so that when added to water, they quickly arrange themselves into groups which minimise the contact of the hydrophobic ends with the water molecules. The particles of grease are attracted and trapped by the hydrophilic shells of these spherical clusters. The way in which a certain species of soap-like molecules, known as CTAB, aggregate and deform when subjected to uneven stresses, is the study of physicists Professor Paul Callaghan and Dr Elmar Fischer at Massey University. In solution, the molecules form giant worm-like slinkies, whose viscosity - the ease with which they flow - depends on the stress they feel. The easy reversibility of this viscosity, by applying or relaxing stress, makes such substances useful in many different industrial situations. For example, by adding them to water-heating pipes, the water can be made to flow more smoothly, minimising heat loss. The oil industry uses surfactants toopen or seal cracks in porous rocks. In their more viscous state, the "sticky" molecules effectively block the holes, when less viscous, they aid the flow of oil.   The Massey University investigations parallel research carried out by a French team, using CTAB molecules. Whilst many of their results "agree nicely" with the French findings, a surprising and very important difference has focused international interest on the Marsden-funded team. Intuitively, one imagines that these long, elastic slinkies, when lined up, would flow more easily, that the layers would slide smoothly over each other. Professor Callaghan and postdoctoral fellow DrFischer have found instead thatthe flow is constantly changing from one where they slip past each other easilyto one which resists slipping, and then back again. They have yet to discoverthe physical mechanism driving this rapid cycle. The idea of such alignment causing high viscosity is not new. US researchers have reported what they call a shear-induced gel in a similar system. The novel aspect of Professor Callaghan and Dr Fischer's work is the discovery of this fast-fluctuating cycle which underlies an apparently steady state. The team has the advantage of a purpose-built device of their own design. The fluid is placed between two cylinders, one still and the other rotating. At the same time, they use nuclear magnetic resonance (NMR) techniques to track the behaviour of certain atoms in the molecules. NMR, of which Professor Callaghan is an acknowledged expert, enables them to work out the relative positions of hydrogen atoms (deuterium "spies") in the molecules and their response to the stress imposed by the rotating cylinder. An important aspect of the research is the effect that shearing stress has on the temperature at which phase transitions occur. In this case, the transition is from a disordered state to one where all the molecular assemblies point in the same direction. The ability to manipulate transition temperatures is of potential importance in the development of new, so-called "smart" materials. Professor Callaghan's work is at the intersection of physics, chemistry and biology. The human body uses the reversible properties of such materials with typical ingenuity. For example, the synovial fluid behind the knee quickly firms to a protective gel if the knee receives a knock or twist. Now that the Massey University team has a good working model of CTAB behaviour, the challenge is to determine the underlying chemical and physical processes. Professor Callaghan believes that these molecular systems are well worth studying for their "beautiful physical properties" as much as for their commercial possibilities, and is expecting more surprises along the way. Note: Professor Callaghan has recently accepted a position as Professor of Chemical Physics at Victoria University of Wellington and he and his team will continue the project there. In May, he was elected a Fellow of the Royal Society of London, and on 4 July, at a special ceremony in Wellington, he was announced the inaugural holder of the Alan MacDiarmid Chair of Physical Sciences at Victoria University. Massey has also honoured Professor Callaghan's achievements by appointing him recently as the first Sir Neil Waters Distinguished Professor. Note: Research assistant, Dr Elmar Fischer, has now returned to Germany, and is replaced by Dr William Holmes from Nottingham and Ms Rosario Lopez, a PhD student from Mexico. For further information, contact Professor Paul Callaghan, School of Chemical and Physical Sciences, , Victoria University of Wellington, , P O Box 600, Wellington , Tel: (04)4635945 , Email: paul.callaghan@vuw.ac.nz   Weta throw light on the mechanics of evolution   Up to 2 million years ago (in the Pliocene) Northland comprised five islands, each with its own chromosome race of weta. Today, the islands have become part of the mainland and the races of weta now interbreed along the old island boundaries, which have become hybrid zones. Two to five million years ago (in the Pliocene period), the Auckland tree weta (Hemideina thoracica) lived on the five islands which comprised Northland. For example, North Cape and Karikari Peninsula were islands each with their own race of tree weta. Superficially these races looked alike but, under their spines, the number and shape of their chromosomes differed. Onmainland Auckland, weta kept their 15 chromosomes but on the Pliocene islands to the north, races evolved with 17, 19 and 23 chromosomes. In human terms, it was as if Englishmen, Irishmen, and Channel Islanders had all evolved different numbers of chromosomes. Over the last 1.8 million years, sand spits have built up and reconnected the ancient Northland islands to each other and to the mainland, so the once-isolated and different chromosome races of weta are now back in touch with each other. Now Marsden recipients, Drs Mary Morgan-Richards and Graham Wallis at Otago University are very interested in the evolution of new species. The Northland weta provide them with a rare opportunity to see the mechanics of speciation in action. Between 1997 and 2000 these researchers found that the once-isolated chromosome races of weta mate with each other along the old island boundaries which now mark "hybrid zones". This hybridising was surprising because with most animal species, such big chromosomal differences would prevent them from crossing. The width of these hybrid zones was mapped, the flow of genes across the zones measured, and the fertility of the hybrid weta inferred from the width of the hybrid zones. At the outset, Drs Morgan-Richards and Wallis supposed that those weta with the biggest chromosomal differences would be the least likely to hybridise but they have found this not to be the case. Other less obvious genetic differences apparently set barriers between the races. The team found that weta can disperse between 80 and 100 m per generation and that, despite big chromosomal differences, some fertile and successful hybrids turn up far from their old boundaries. Near Kaitaia, for example, hybrids were found over a zone 50 km wide. Other races of weta did not hybridise nearly as extensively. Near the Waitangi River, for example, hybrids between former chromosome races were found only over a 500m boundary strip. Rarely in evolutionary field studies can we put numbers on genetic advantages or disadvantages, but the researchers have done just that. They can say that, when it comes to hybridising, one long-isolated race of weta has a hundred-fold advantage over another. For further information, contact Dr Graham Wallis, Department of Zoology, University of Otago, P.O. Box 56, Dunedin Tel: (03) 479 7984 Email: graham.wallis@stonebow.otago.ac.nz or Dr Mary Morgan-Richards, The Natural History Museum, London Email: M.Morgan-Richards@nhm.ac.uk News from Marsden Cottage by Dr Valda McCann, Manager, Marsden Fund Professor MacDiarmid and Dr McCann at Government House In his visit to New Zealand in July, Nobel Prize winner, Professor Alan MacDiarmid, impressed us all with his enjoyment in his research, his energy and his commitment to New Zealand. In his speeches, he extolled the benefits of basic research and following what holds one's fascination, and also of applying the results of research. He is enthusiastic about the Marsden Fund and has kindly offered to help in locating outstanding New Zealanders who work overseas, so that we have more such people on our database to help with refereeing and advice. Overseas funding agencies In June, Professor Diana Hill (Chair of the Marsden Fund) and I visited more than 20 different funding agencies in Germany, England, Ireland, Sweden, Finland, USA and Canada, to ensure that our processes measured up to international standards, to explore opportunities for New Zealand researchers, and to strengthen our international networks. We concluded that our standards are good but it is always worthwhile considering other ways of operation. It is interesting that no matter what the size of the funding, there were concerns that were common to all (including the Marsden Fund), such as ensuring that interdisciplinary research is not penalised by the assessing system, that panellists are not only good researchers but include younger people, and that systems are in place to encourage emerging researchers. The agencies were all keen to encourage collaboration with researchers here. Later, we will send out information about some strategies for this. The larger agencies had the luxury of accepting applications at any time. Some had excellent schemes for publicising research and making the results more generally known. Others targeted special areas to encourage interdisciplinary research. Centres of Excellence or similar groupings were of great and timely interest to us. The Marsden Committee will be discussing the information we gathered and evaluating it to see whether some ideas can be usefully adapted to use here. I am sure that we have made some invaluable contacts. Every year, we get some cases where it is very difficult to find appropriate referees and we have offers of advice for these problems in the future. Full proposal panel meetings The meetings to discuss the full proposals to the Fund (see table) are being held in August, with the results being sent out in early September. Most people have received at least three referees' reports. The Marsden Fund asked 892 people to referee proposals and 564 people agreed, but about 3% of these people have not provided reports. At this stage we are not hopeful about receiving the remaining reports but any that do arrive will be processed right up until the panel meetings. The panellists are aware that the referees come from a range of countries with different funding systems, so the overall grades have to be viewed in the light of the referees' comments. Numbers of applications Since the March issue of Update the numbers of preliminary proposals have been updated to reflect the fact that a number of proposals were sent to extra panels on the advice of the committee. Tracking postdoctoral fellows The survey to track postdoctoral fellows is about to get under way. As I mentioned in this page last year, we wish to find out what happens to postdoctoral fellows who have been part of a Marsden contract. They will be asked about their subsequent careers, and such questions as whether they are now in New Zealand or overseas, and the reasons why. The results of the survey will be important information for policy discussions about career paths for researchers. The survey is being carried out in collaboration with the Foundation for Research, Science and Technology and the Health Research Council. We expect to repeat this at regular intervals in the future so if you have a postdoctoral fellow on your Marsden contract, please ensure we have the person's details. Marsden staff news Dr Rachel Averill has been on parental leave since the end of October last year and has been looking after her twins, Rebecca and Thomas. We are very pleased to welcome her back and she has already started to read some of the reports from Marsden researchers. From 1 August, she will be working 3 days a week. Dr Jo Lorimer, who has been standing in for Rachel, has returned to the United Kingdom. Jo met a number of Marsden researchers in her monitoring visits to Wellington, Hamilton, Auckland, Christchurch and Dunedin, and filled in for Rachel extremely well. We wish her well for her stay in Newcastle. We are delighted to welcome Dr Andrea Knox, who has joined research assessment for the next 3 months. Andrea is a graduate in biology from Massey and has returned recently from doctoral and postdoctoral experience at Cambridge University, where her research was on characterising genes that modulate the integrin function in Drosophila. Andrea is a Kiwi, so I hope the science system can keep her in New Zealand.

Putting water distribution under the microscope

A team of Marsden researchers, based at HortResearch in Palmerston North, is pioneering a new field in soil science, based on an imaging technique developed by Professor Paul Callaghan, from Massey University.

Drs Iris Vogeler and Markus Deurer, from the Environment and Risk Management Group, and Dr Dave Scotter, from Massey, have been using a nuclear magnetic resonance imaging (NMRI) microscope to study how water and dissolved substances move through soils.

So far, the group has restricted their work to a model soil, constructed by randomly packing 2mm diameter glass beads into a cylinder. Water is then pumped through the cylinder at an average velocity of about 1mm per second. The research team has been able to visualise the distribution of water in the pores and, more importantly, the speed at which the water is moving.

 

A: End-on view of the velocity distribution through a slice of thickness 2mm. Some of the beads, particularly in the top half of the cross-section, are apparent as white or grey areas that are roughly circular. Regions of "high-speed" flow (~ 3mm/second) are black. Thus, it can be seen that the flow appears in isolated channels confined by the beads. B: End-on view of the velocity distribution through a slice of thickness 8mm. With this thicker cross-section, the various pathways tend to average out, which shows up as a more uniform distribution of velocities, particularly in the centre of the cross-section.

In visualising the flow, the group has divided the cylinder into slices, as little as 2mm in thickness, and made measurements of the water velocity every tenth of a millimetre or so, across the whole area of the slice. In soil science where, until now, all measurements of flow have been on a much coarser scale, this microscopic approach is unique.

Their work could have important implications for plant nutrient utilisation and environmental pollution.

"Fluid flow through a porous medium is a phenomenon of importance in both nature and industrial production processes," said Dr Vogeler.

"However an inability to observe the geometrically complex flow through the pores has limited our understanding of the way water-borne pollutants, for example, spread out as they travel through the soil.

This spread is caused by the geometry of the pore network itself. For example, the connectivity and tortuosity of pores and their size distribution create local variations in the flow rate.

"By restricting the thickness of our slice to 2mm, we can observe flow over distances comparable to the size of the beads, where large variations in flow velocity can be observed. For thicker slices, the various pathways for the flow tend to average out and the flow rate appears more uniform.

"In making mathematical models of flow in porous media, it is important to know this distance over which the properties even out. Until now, this has not been possible."

Dr Vogeler said that by assembling thousands of their microscopic measurements, the group has been able to compare its results with those of more conventional techniques and show that their method works. A highlight so far has been to confirm a forty-year-old mathematical model of flow through porous media that had not been confirmed because no-one could see the necessary level of detail.

Dr Vogeler said that, in time, the NMRI method would be applied to real soils and a variety of flow phenomena.

For further information, contact Dr Iris Vogeler, Environment and Risk Management Group, HortResearch, Private Bag 11 - 030, Palmerston North Tel: (06) 356 8080 Email: ivogeler@hortresearch.co.nz

Rock sponges - "living fossils"

Dr Kelly sorts sponges from sea floor dredgings

Lithistid sponges are the living relatives of ancient forms of life (up to 145 million years), which are prized by pharmaceutical companies for their potential to produce promising anti-cancer drugs. A substance called discodermolide, extracted from the juice of an Atlantic sponge, seems to be particularly effective against breast cancer and is currently being trialled in the States.

These sponges live deep in our coastal waters, from East Cape northwards, so deep that little is known about their reproductive habits. Unlike the collagen-based skeletons we use in the bathroom, lithistid sponges are as hard as rocks, being made of silica (Lithos is Greek for rock). You can easily clone sponges by simply cutting them into pieces, since they do not have specialised tissues. However, with rock sponges, this may not be so simple.

The different locations of lithistid fossils (West Coast, Oamaru, Chatham Islands) and identical or almost identical living sponges (north of Gisborne) suggest two possibilities: either New Zealand has drifted south and/or the climate has become colder, driving themnorthwards. Dr Michelle Kelly, a NIWA biologist, and Professor John Buckeridge, a palaeontologist from Auckland University of Technology, have been awarded Marsden funding to learn about lithistid sponge evolution and eventsin New Zealand's ocean and climate history which have influenced the present-day distribution.

There is a rich fossil record for them to study. Many fossils were collected in the late 1800s by Julius Von Haast (the road builder), when fossil-hunting was a popular pastime of Victorian gentlemen. Most were found in the Oamaru area, which may have once enjoyed a sub-tropical climate.

 

Top:Professor John Buckeridge and Dr Daphne Lee search for fossil rock sponges at the mouth of the Kakanui River.Below:Fossil rock sponges.

More recently, Otago geologist Dr Daphne Lee found a group of beautifully preserved fossils at the mouth of the Kakanui River in Oamaru. Their disposition throughout a thick limestone band suggests that they were transported intact from their habitat, possibly an underwater volcano, by a flow of debris. These sponges represent a new species and are the first lithistid body fossils to be found in material aged between 25 and 40 million years old. The most exciting aspect of this discovery is that the fossils are almost indistinguishable from a species of sponge (genus Pleroma) found on isolated underwater banks north-west of New Zealand. They have been called "living fossils" because of the close similarity.

Evaluating the fossils requires some inspired scientific "guesswork", since the silica has largely been replaced by calcite. Dr Kelly has collected her samples of living sponges from several hundred voyages by New Zealand Oceanographic Institute/NIWA vessels, which dredge the ocean floor. In the last 2 years, she has identified and documented 33 species of lithistid, from base data of just one. This phenomenal diversity makes New Zealand the ideal place to study lithistids.

Whilst Dr Kelly studies their evolutionary history through DNA sequencing and her knowledge of other living species, Professor Buckeridge is able to hypothesise about their life story from his knowledge of Earth's geological past.

Dr Kelly has studied lithistids since her first post-doctoral position at the Harbor Branch Oceanographic Institute, Florida. Interest by pharmaceutical companies in the sponges was keen because of their biomedical potential, and Dr Kelly advised on likely habitats and sustainable harvesting. She also worked for 4 years at the Natural History Museum in London, which was the beneficiary of Von Haast's "Oamaru" collection.

The Marsden-funded project will be completed in March 2002.

For further information, contact Dr Michelle Kelly, National Institute of Water and Atmospheric Research (NIWA) Ltd, Private Bag 109-695, Newmarket 269 Khyber Pass Road, Newmarket, Auckland Tel: (09) 375-2037 Email m.kelly@niwa.cri.nz  

Banking on price stability

Dr Paul Dalziel

University of Canterbury economist, Dr Paul Dalziel, has just published a book with Routledge Press on his Marsden research project, funded in 1998/9.

The research was based on the 1989 reform of the Reserve Bank of New Zealand Act to make price stability, or inflation control, the sole objective of monetary policy. New Zealand was the first country to adopt this practice, but its example is now followed by many other countries, including the United Kingdom and Canada.

Dr Dalziel's book, entitled "Money, Credit, and Price Stability", devotes a chapter to explaining the method of research he used, called "process analysis". Normally, such economic studies would look at the effect of changing one or more economic variables and then, using standard mathematical techniques, estimate what the impact would be on other economic variables after a certain period of time, say 10 years. This method is called "comparative statics". With process analysis, you track month by month changes to gain more understanding of what's actually happening. Says Dr Dalziel, "It's important to analyse where the economy moves to after a change, but it's sometimes even more important to understand how it gets there."

Having explained the method of process analysis, the book elaborates on the focus of Dr Dalziel's study, the ways in which a central bank controls inflation by using interest rate changes to alter the demand for credit.

Dr Dalziel says that the main contribution of the research project is to explore the role played by bank customers in the implementation of monetary policy - how they respond to interest rate changes. Says Dr Dalziel, "In modern economies, almost all money takes the form of cheque accounts held in banks. The total value of these accounts is determined by the rate of growth in bank loans to their customers, and so it is important to understand how monetary policy affects the demand for credit.

"The analysis shows how the Reserve Bank controls inflationary pressures by raising interest rates. The higher interest rates reduce the demand for bank loans. This produces lower growth of bank deposits, and so the money supply tightens. This keeps inflation under control, but there is a side effect. The higher interest rates also make it more expensive to borrow for investment in new buildings, plant and machinery. A lower rate of investment causes economic growth to fall.

"To avoid this negative trade-off between inflation control and economic growth, it is important that companies, who are the price-setters, see that the Reserve Bank's commitment to price stability is genuine and credible. This stops inflationary pressures building up in the first place. The Reserve Bank makes extensive communications efforts to emphasise that commitment and to signal concerns well in advance, thus minimising the need for interest rate hikes."

For further information, contact Dr Paul Dalziel, Department of Economics, University of Canterbury, Private Bag 4800, Christchurch Tel: (03) 3642521 Email: p.dalziel@econ.canterbury.ac.nz

Comparing the floras and vegetation of New Zealand and the Andes

Blechnum magellanicum in forest dominated by Caldcluvia paniculata and Podocarpus nubigena. Salto Río Padre Garcia, Río Queulat, Chile.Reproduced with permission of RSNZ from Wardle et al.(2001), Comparison of the flora and vegetation of the southern Andes and New Zealand. New Zealand Journal of Botany 39: 69-108.

Since Darwin's day, botanists have known that the vegetation of New Zealand and the southern Andes has many similarities and parallels. For example, some species of hard fern, filmy fern, sedge, rush, grass, geranium, dandelion, chickweed, koromiko, Montia and Samolus grow both in New Zealand and South America and we each have slightly different versions of button plant and kowhai.

Such similarities have prompted years of speculation about the origins and antiquity of the two floras. To put the speculations on a surer footing, botanists and Marsden recipients Drs Peter Wardle and Steve Wagstaff of Landcare Research, Lincoln, joined forces with Drs Cecilia Ezcurra and Carlos Ramirez from Argentina and Chile to compare 26 carefully matched pairs of plant communities at sites in New Zealand and the southern Andes. These ranged from beech forest and tussock grasslands, to alpine zones and coastal marshes.

The group aimed to find which plants had common ancestors in ancient Gondwanaland, which similarities were caused by parallel evolution, and which similarities are due to the long-range dispersal of seeds across the Pacific. As well as comparing the types of vegetation, the group also looked into the molecular clocks of 22 shared species or pairs of closely related species. The molecular clock indicates how long ago these paired plants last had a common ancestor.

The team found that the New Zealand and South American species of the dwarf podocarp Lepidothamnus last had a common ancestor about 100 million years ago. At that time South America, Antarctica and Australasia were part of the Gondwanaland continent so the group could label the little podocarp a true Gondwanan.

New Zealand and South American species of beech, broadleaf and kamahi evolved from a common ancestor about 50 million years ago, after New Zealand separated from the rest of Gondwanaland including Australia. Therefore, although these tree genera are Gondwanan, New Zealand probably received them as seeds carried across the sea from Antarctica or Australia.

 

This New Zealand koromiko (Hebe salicifolia) probably colonised the coast of Chile within the last 7 million years. Illustration: Bob Brockie

The botanists found that the tough alpine habitat in both New Zealand and the Andes forced many species to evolve along similar lines. Many alpine cushion plants, for example, look the same but are botanically unrelated.

Before the ice closed it down, Antarctica enjoyed a milder climate, and some scientists consider that fossil beech foliage recently discovered only 500km from the South Pole is only 3 million years old. This led Dr Wardle and his team to suggest that bog and alpine plants such as Donatia, Phyllachne, and Tetrachondra may have used the continent as a fairly recent stepping stone between Australasia and South America.

Several plants were found to be relative newcomers to each other's coasts. As examples, the New Zealand tree tutu and common koromiko probably colonised Chilean coasts within the last 7 million years, and must have found their way over the sea, whether as floating seeds, branches or on birds' feet, is unknown.

For further information, contact Dr Peter Wardle, Landcare Research, P.O. Box 69, Lincoln Tel: (03) 3489724 Email: wardlep@landcare.cri.nz

Marsden Update is published quarterly by the Marsden Fund and is available free by request from the editor, Glenda Lewis.