̽��ֱ�� of Cambridge - Paul Dupree

Cambridge academics win European Research Council Advanced Grants

cg605 — Tue, 26 Apr 2022 11:14:19 +0000

Nine Cambridge academics have won Advanced Grants awarded by the European Research Council (ERC). This is the greatest number of grants won by a UK institution in the 2021 round of funding.

̽��ֱ��'P' word

lw355 — Thu, 16 Jan 2020 08:00:00 +0000

How do we shift our 'take, make, throw-away' plastic world towards 'recycle, recover, re-use'? It's time for blue-sky thinking plus practical measures in the battle to reduce plastic waste.

Revealing the nanostructure of wood could help raise height limits for wooden skyscrapers

jg533 — Wed, 23 Oct 2019 04:00:00 +0000

There is increasing interest around the world in using timber as a lighter, more sustainable construction alternative to steel and concrete. While wood has been used in buildings for millennia, its mechanical properties have not, as yet, measured up to all modern building standards for major superstructures. This is due partly to a limited understanding of the precise structure of wood cells.

̽��ֱ��research, published today in the journal Frontiers in Plant Science, has also identified the plant Arabidopsis thaliana as a suitable model to help direct future forestry breeding programmes.

Dr Jan Lyczakowski, the paper’s first author from Cambridge ̽��ֱ��’s Department of Biochemistry, who is now based at Jagiellonian ̽��ֱ��, said, “It is the molecular architecture of wood that determines its strength, but until now we didn’t know the precise molecular arrangement of cylindrical structures called macrofibrils in the wood cells. This new technique has allowed us to see the composition of the macrofibrils, and how the molecular arrangement differs between plants, and it helps us understand how this might impact on wood density and strength.”

̽��ֱ��main building blocks of wood are the secondary walls around each wood cell, which are made of a matrix of large polymers called cellulose and hemicellulose, and impregnated with lignin. Trees such as the giant sequoia can only achieve their vast heights because of these secondary cell walls, which provide a rigid structure around the cells in their trunks.

̽��ֱ��team from Cambridge ̽��ֱ��’s Department of Biochemistry and Sainsbury Laboratory (SLCU) adapted low-temperature scanning electron microscopy (cryo-SEM) to image the nanoscale architecture of tree cell walls in their living state. This revealed the microscopic detail of the secondary cell wall macrofibrils, which are 1000 times narrower than the width of a human hair.

To compare different trees, they collected wood samples from spruce, gingko and poplar trees in the Cambridge ̽��ֱ�� Botanic Garden. Samples were snap-frozen down to minus 200°C to preserve the cells in their live hydrated state, then coated in an ultra-thin platinum film three nanometres thick to give good visible contrast under the microscope.

“Our cryo-SEM is a significant advance over previously used techniques and has allowed us to image hydrated wood cells for the first time”, said Dr Raymond Wightman, Microscopy Core Facility Manager at SLCU. “It has revealed that there are macrofibril structures with a diameter exceeding 10 nanometres in both softwood and hardwood species, and confirmed they are common across all trees studied.”

Cryo-SEM is a powerful imaging tool to help understand various processes underlying plant development. Previous microscopy of wood was limited to dehydrated wood samples that had to be either dried, heated or chemically processed before they could be imaged.

̽��ֱ��team also imaged the secondary cell walls of Arabidopsis thaliana, an annual plant widely used as the standard reference plant for genetics and molecular biology research. They found that it too had prominent macrofibril structures. This discovery means that Arabidopsis could be used as a model for further research on wood architecture. Using a collection of Arabidopsis plants with different mutations relating to their secondary cell wall formation, the team was able to study the involvement of specific molecules in the formation and maturation of macrofibrils.

Dr Matthieu Bourdon, a research associate at SLCU, said, “ ̽��ֱ��variants of Arabidopsis allowed us to determine the contribution of different molecules - like cellulose, xylan and lignin - to macrofibril formation and maturation. As a result, we are now developing a better understanding of the processes involved in assembling cell walls.”

̽��ֱ��wealth of Arabidopsis genetic resources offers a valuable tool to further study the complex deposition of secondary cell wall polymers, and their role in defining the fine structure of cell walls and how these mature into wood.

“Visualising the molecular architecture of wood allows us to investigate how changing the arrangement of certain polymers within it might alter its strength,” said Professor Paul Dupree, a co-author of the study in Cambridge’s Department of Biochemistry. “Understanding how the components of wood come together to make super strong structures is important for understanding both how plants mature, and for new materials design.”

“There is increasing interest around the world in using timber as a lighter and greener construction material,” added Dupree. “If we can increase the strength of wood, we may start seeing more major constructions moving away from steel and concrete to timber.”

Professor Dupree and Dr Lyczakowski are involved in the Leverhulme Trust funded Natural Material Innovation Centre where a team of biochemists, plant scientists, architects, mathematicians and chemists at the ̽��ֱ�� of Cambridge is working towards better understanding of wood structure, modification and application. ̽��ֱ��researchers are hoping they can make wooden skyscrapers, and even wooden cars, a reality by re-engineering the structure of wood in order to make better materials for construction and manufacturing. Their work was recently showcased at the Royal Society Summer Science Exhibition in London.

This study was supported by the Leverhulme Trust Centre for Natural Material Innovation, US Department of Energy, BBSRC, ERC and Gatsby Charitable Foundation.

Reference

J. Lyczakowski et al. ‘Structural imaging of native cryo-preserved secondary cell walls reveals the presence of macrofibrils and their formation requires normal cellulose, lignin and xylan biosynthesis.’ Frontiers in Plant Science (2019) DOI:10.3389/fpls.2019.01398

Cambridge researchers have captured the visible nanostructure of living wood for the first time using an advanced low-temperature scanning electron microscope.

Understanding how the components of wood come together to make super strong structures is important for understanding both how plants mature, and for new materials design.

Paul Dupree

Microscopic structure of spruce wood

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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‘Glue’ that makes plant cell walls strong could hold the key to wooden skyscrapers

cjb250 — Wed, 21 Dec 2016 09:05:15 +0000

̽��ֱ��two most common large molecules – or ‘polymers’ – found on Earth are cellulose and xylan, both of which are found in the cell walls of materials such as wood and straw. They play a key role in determining the strength of materials and how easily they can be digested.

For some time, scientists have known that these two polymers must somehow stick together to allow the formation of strong plant walls, but how this occurs has, until now, remained a mystery: xylan is a long, winding polymer with so-called ‘decorations’ of other sugars and molecules attached, so how could this adhere to the thick, rod-like cellulose molecules?

“We knew the answer must be elegant and simple,” explains Professor Paul Dupree from the Department of Biochemistry at the ̽��ֱ�� of Cambridge, who led the research. “And in fact, it was. What we found was that cellulose induces xylan to untwist itself and straighten out, allowing it to attach itself to the cellulose molecule. It then acts as a kind of ‘glue’ that can protect cellulose or bind the molecules together, making very strong structures.”

̽��ֱ��finding was made possible due to an unexpected discovery several years ago in Arabidopsis, a small flowering plant related to cabbage and mustard. Professor Dupree and colleagues showed that the decorations on xylan can only occur on alternate sugar molecules within the polymer – in effect meaning that the decorations only appear on one side of xylan. This led the team of researchers to survey other plants in the Cambridge ̽��ֱ�� Botanic Garden and discover that the phenomenon appears to occur in all plants, meaning it must have evolved in ancient times, and must be important.

To explore this in more detail, they turned to an imaging technique known as solid state nuclear magnetic resonance (ssNMR), which is based on the same physics as hospital MRI scanners, but can reveal structure at the nanoscale. However, while ssNMR can image carbon, it requires a particular heavy isotope of carbon, carbon-13. This meant that the team had to grow their plants in an atmosphere enriched with a special form of carbon dioxide – carbon-13 dioxide.

Professor Ray Dupree – Paul Dupree’s father, and a co-author on the paper – supervised the work at the ̽��ֱ�� of Warwick’s ssNMR laboratory. “By studying these molecules, which are over 10,000 times narrower than the width of a human hair, we could see for the first time how cellulose and xylan slot together and why this makes for such strong cell walls.”

Understanding how cellulose and xylan fit together could have a dramatic effect on industries as diverse as biofuels, paper production and agriculture, according to Paul Dupree.

“One of the biggest barriers to ‘digesting’ plants – whether that’s for use as biofuels or as animal feed, for example – has been breaking down the tough cellular walls,” he says. “Take paper production – enormous amounts of energy are required for this process. A better understanding of the relationship between cellulose and xylan could help us vastly reduce the amount of energy required for such processes.”

But just as this could improve how easily materials can be broken down, the discovery may also help them create stronger materials, he says. There are already plans to build houses in the UK more sustainably using wood, and Paul Dupree is involved in the Centre for Natural Material Innovation at the ̽��ֱ�� of Cambridge, which is looking at whether buildings as tall as skyscrapers could be built using modified wood.

̽��ֱ��research was funded by the Biotechnology and Biological Sciences Research Council (BBSRC).

Reference
Simmons, TJ et al. Folding of xylan onto cellulose fibrils in plant cell walls revealed by solid-state NMR. Nature Communications; Date; DOI: 10.1038/ncomms13902

Molecules 10,000 times narrower than the width of a human hair could hold the key to making possible wooden skyscrapers and more energy-efficient paper production, according to research published today in the journal Nature Communications. ̽��ֱ��study, led by a father and son team at the Universities of Warwick and Cambridge, solves a long-standing mystery of how key sugars in cells bind to form strong, indigestible materials.

We knew the answer must be elegant and simple. And in fact, it was

Paul Dupree

Paul Bica

Vanishing point

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Cellulose: new understanding could lead to tailored biofuels

fpjl2 — Thu, 09 Jun 2016 09:38:08 +0000

Scientists have identified new steps in the way plants produce cellulose, the component of plant cell walls that provides strength, and forms insoluble fibre in the human diet.

̽��ֱ��findings could lead to improved production of cellulose and guide plant breeding for specific uses such as wood products and ethanol fuel, which are sustainable alternatives to fossil fuel-based products.

Published in the journal Nature Communications today, the work was conducted by an international team of scientists, led by the ̽��ֱ�� of Cambridge and the ̽��ֱ�� of Melbourne.

"Our research identified several proteins that are essential in the assembly of the protein machinery that makes cellulose," said Melbourne's Prof Staffan Persson.

“We found that these assembly factors control how much cellulose is made, and so plants without them can not produce cellulose very well and the defect substantially impairs plant biomass production. ̽��ֱ��ultimate aim of this research would be breed plants that have altered activity of these proteins so that cellulose production can be improved for the range of applications that use cellulose including paper, timber and ethanol fuels."

̽��ֱ��newly discovered proteins are located in an intracellular compartment called the Golgi where proteins are sorted and modified.

“If the function of this protein family is abolished the cellulose synthesizing complexes become stuck in the Golgi and have problems reaching the cell surface where they normally are active” said the lead authors of the study, Drs. Yi Zhang (Max-Planck Institute for Molecular Plant Physiology) and Nino Nikolovski ( ̽��ֱ�� of Cambridge).

“We therefore named the new proteins STELLO, which is Greek for to set in place, and deliver.”

“ ̽��ֱ��findings are important to understand how plants produce their biomass,” said Professor Paul Dupree from the ̽��ֱ�� of Cambridge's Department of Biochemistry.

“Greenhouse-gas emissions from cellulosic ethanol, which is derived from the biomass of plants, are estimated to be roughly 85 percent less than from fossil fuel sources. Research to understand cellulose production in plants is therefore an important part of climate change mitigation.”

“In addition, by using cellulosic plant materials we get around the problem of food-versus-fuel scenario that is problematic when using corn as a basis for bioethanol.”

“It is therefore of great importance to find genes and mechanisms that can improve cellulose production in plants so that we can tailor cellulose production for various needs.”

Previous studies by Profs. Persson’s and Dupree’s research groups have, together with other scientists, identified many proteins that are important for cellulose synthesis and for other cell wall polymers.

With the newly presented research they substantially increase our understanding for how the bulk of a plant’s biomass is produced and is therefore of vast importance to industrial applications.

̽��ֱ��work was funded, in part, by the BBSRC and was conducted with the BBSRC Sustainable Bioenergy Centre Cell Wall Sugars Programme.

Adapted from a ̽��ֱ�� of Melbourne press release.

In the search for low emission plant-based fuels, new research may help avoid having to choose between growing crops for food or fuel.

By using cellulosic plant materials we get around the problem of food-versus-fuel scenario that is problematic when using corn as a basis for bioethanol

Paul Dupree

Nino Nikolovski and Paul Dupree

Arabidopsis seeds exude slime that is attached to the seed by cellulose. On the left is a seed with normal slime stained pink, but on the right, in the stello mutant, the slime is lost because the cellulose is missing.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Breeding better grasses for food and fuel

gm349 — Tue, 17 Jan 2012 10:31:03 +0000

Researchers from the Biotechnology and Biological Sciences Research Council (BBSRC) Sustainable Bioenergy Centre (BSBEC) have discovered a family of genes that could help us breed grasses with improved properties for diet and bioenergy.

̽��ֱ��research was carried out by a team from the ̽��ֱ�� of Cambridge and Rothamsted Research, which receives strategic funding from BBSRC. Their findings are published today (Tuesday 17 Jan) in the journal Proceedings of the National Academy of Sciences (PNAS).

̽��ֱ��genes are important in the development of the fibrous, woody parts of grasses, like rice and wheat. ̽��ֱ��team hopes that by understanding how these genes work, they might for example be able to breed varieties of cereals where the fibrous parts of the plants confer dietary benefits or crops whose straw requires less energy-intensive processing in order to produce biofuels.

̽��ֱ��majority of the energy stored in plants is contained within the woody parts, and billions of tons of this material are produced by global agriculture each year in growing cereals and other grass crops, but this energy is tightly locked away and hard to get at. This research could offer the possibility of multi-use crops where the grain could be used for food and feed and the straw used to produce energy efficiently. This is crucial if we are to ensure that energy can be generated sustainably from plants, without competing with food production.

Professor Paul Dupree, of the ̽��ֱ�� of Cambridge's Department of Biochemistry, explains, “Unlike starchy grains, the energy stored in the woody parts of plants is locked away and difficult to get at. Just as cows have to chew the cud and need a stomach with four compartments to extract enough energy from grass, we need to use energy-intensive mechanical and chemical processing to produce biofuels from straw.

“What we hope to do with this research is to produce varieties of plants where the woody parts yield their energy much more readily – but without compromising the structure of the plant. We think that one way to do this might be to modify the genes that are involved in the formation of a molecule called xylan – a crucial structural component of plants.”

Xylan is an important, highly-abundant component of the tough walls that surround plant cells. It holds the other molecules in place and so helps to make a plant robust and rigid. This rigidity is important for the plant, but locks in the energy that we need to get at in order to produce bioenergy efficiently.

Grasses contain a substantially different form of xylan to other plants. ̽��ֱ��team wanted to find out what was responsible for this difference and so looked for genes that were turned on much more regularly in grasses than in the model plant Arabidopsis. Once they had identified the gene family in wheat and rice, called GT61, they were able transfer it into Arabidopsis, which in turn developed the grass form of xylan.

Dr Rowan Mitchell of Rothamsted Research continues, "As well as adding the GT61 genes to Arabidopsis, we also turned off the genes in wheat grain. Both the Arabidopsis plants and the wheat grain appeared normal, despite the changes to xylan. This suggests that we can make modifications to xylan without compromising its ability to hold cell walls together. This is important as it would mean that there is scope to produce plant varieties that strike the right balance of being sturdy enough to grow and thrive, whilst also having other useful properties such as for biofuel production."

̽��ֱ��tough, fibrous parts of plants are also an important component of our diet as fibre. Fibre has a well established role in a healthy diet, for example, by lowering blood cholesterol. ̽��ֱ��team have already demonstrated that changing GT61 genes in wheat grain affects the dietary fibre properties so this research also offers the possibility of breeding varieties of cereals for producing foods with enhanced health benefits.

Duncan Eggar, BBSRC Bioenergy Champion said: “Recent reports have underlined the important role that bioenergy can play in meeting our future energy needs – but they all emphasise that sustainability must be paramount.

“Central to this will be ensuring that we can get energy efficiently from woody sources that need not compete with food supply. This research demonstrates how, by understanding the fundamental biology of plants, we can think about how to produce varieties of crops with useful traits, specifically for use as a source of energy.”

Newly discovered family of genes could help us breed grasses with improved properties for food and fuel.

Unlike starchy grains, the energy stored in the woody parts of plants is locked away and difficult to get at. Just as cows have to chew the cud and need a stomach with four compartments to extract enough energy from grass, we need to use energy-intensive mechanical and chemical processing to produce biofuels from straw.

Professor Paul Dupree, of the ̽��ֱ�� of Cambridge's Department of Biochemistry

Rowan Mitchell, Rothamsted Research

Plant cells, like these in wheat, are surrounded by thick walls where energy is locked up.

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Bioenergy research blooms in Cambridge

bjb42 — Sun, 01 Aug 2010 14:41:57 +0000

Plants are the most important natural resource on the planet. Not only do they provide all the food we eat, either directly or indirectly as animal feed, but they are also an important source of building materials and biopolymers, such as rubber, as well as many important pharmaceutical products.

Now plants are increasingly being exploited as a source of renewable energy. Plants harness solar radiation by photosynthesis; because this fixes atmospheric CO₂ to produce biomass, using plants as a source of energy is potentially carbon neutral. In addition, compared with other sources of renewable energy, biofuels also offer the major advantage of providing a source of liquid fuel, which is required for transport.

But biofuels have also come under criticism. So-called first-generation biofuels are produced by fermentation of starch from crops such as maize to yield ethanol, or are derived from plant oils yielding biodiesel. Although the amounts produced are small (approximately 3% of European transport fuel energy consumption comes from first-generation biofuels), the use of food crops as a source of raw materials at a time when populations are increasing in size has led to a ‘food versus fuel’ debate.

Sources of alternative biofuel feedstock that don’t compete with food production are needed. Within the past two years, scientists from several Cambridge departments have come together to form the Bioenergy Initiative to explore the potential of next-generation biofuels. These interdisciplinary collaborations are tackling the technical and environmental obstacles that must be addressed to make next-generation biofuels commercially viable. ̽��ֱ��research is focusing on two main areas: developing fuels based on non-food crops and the parts of food crops that are normally discarded as waste, and developing ways of harvesting energy from algae.

Plants for bioenergy

Plant material such as wood and straw has the potential to be part of the low carbon solution to replace our fossil-fuel-based liquid transport fuels, provided an environmentally, socially and economically sustainable production method is found. Plants store most of the carbon they take from the atmosphere in their cell walls as polysaccharides. Instead of burning plants to release energy, the plant biomass could be more usefully converted to liquid fuels such as ethanol by chemically releasing these sugars, and then using microbes to ferment them to fuels. This requires that as much as possible of the cell wall polysaccharides are used, with minimal expenditure of energy and minimal use of expensive chemical and enzymatic treatment to extract them. Much research is needed to make this an industrial reality.

Early in 2009, the UK Biotechnology and Biological Sciences Research Council (BBSRC) announced a £27 million investment in research in this area. ̽��ֱ��new virtual BBSRC Sustainable Bioenergy Centre (BSBEC) is a partnership of six research hubs and industry. As part of this, Dr Paul Dupree in the Department of Biochemistry leads the BSBEC Cell Wall Sugars Programme in Cambridge. ̽��ֱ��Programme aims to improve the energy conversion process by understanding how sugars are locked into the plant biomass.

Up to 10 million tonnes of wheat straw could be available in the UK each year for energy production. If converted to ethanol, this could generate a few percent of UK transport fuel requirements. Increases beyond this are possible if crops such as willow or Miscanthus grass are grown on land that is unsuitable for food crops. Cambridge BSBEC researchers are contributing to studies on the farming of these crops at Rothamsted Research, Hertfordshire, to improve yields and to understand how to optimise sustainability of the crops in terms of energy input and biodiversity.

By analysing how sugars are locked into plant cell walls, research in the Dupree group aims to identify the best plants and the right enzymes to release the maximum amount of sugars for conversion to biofuels. ̽��ֱ��research team is building links with industry and other research centres to ensure their findings will increase the sustainable use of plants for fuels and other renewable products.

Pond slime to the rescue

̽��ֱ��other major strand of research being undertaken in the Initiative has focused on algae. These simple aquatic plants are responsible for an estimated 50% of global carbon fixation and offer considerable advantages compared with biofuels from land crops. Many species are able to produce high levels of hydrocarbons, and they can also divert photosynthetic energy into another ready-to-use fuel, hydrogen. Algal productivity can be much higher than that of land plants per unit area, because of their fast growth rates, and they can be grown on marginal land, or even offshore, where they don’t compete with food crops.

However, there is little or no infrastructure for the cultivation and harvesting of microalgae on a large scale, apart from commercial operations employed for the production of high-value products such as the food supplement astaxanthin, which is used in the fish industry. Moreover, for fuel production, cost margins are critical, and most importantly the energy that is obtained from the fuel extracted must be greater than that used in the process. To address some of the many difficulties that will be encountered in attempts to commercialise biofuel production from algae, the Algal Bioenergy Consortium (ABC) was founded in 2007 by Professor Alison Smith (Department of Plant Sciences), together with Professor Chris Howe (Biochemistry), Dr John Dennis (Chemical Engineering and Biotechnology) and Dr Stuart Scott (Engineering).

A major issue is which algal species to grow. Although most people are familiar with the two broad categories of algae – seaweed on the beach or the scum that grows on ponds or on the patio – the algal kingdom is incredibly diverse. However, our knowledge of algal biology in general is poor, and we know even less about how these organisms would behave in the large-scale dense cultures that would be needed for biofuel feedstock production.

̽��ֱ��research focus of the ABC is to study a few species in depth, taking advantage of molecular tools that are being developed for some model species. Through studying ways in which algae make fuel molecules and how the algal cell wall is built, the researchers aim to discover ways to increase the extraction of fuel molecules with maximum yields.

Together with Dr Adrian Fisher in the Department of Chemical Engineering and Biotechnology, the ABC is also investigating ways of harvesting hydrogen as an energy source in a biophotovoltaic device. ̽��ֱ��method is based on ‘stealing’ electrons from the photosynthetic process. Although currents so far are low, with funding from the Engineering and Physical Sciences Research Council (EPSRC) and the formation of a ̽��ֱ�� spin-out, H+ Energy, the combination of biological and engineering approaches is helping to optimise the prototypes.

Part of the energy spectrum

At the present time, an estimated 1 million years’ worth of fossil fuel deposition is consumed each year. As fossil fuels become scarcer and more expensive to extract, and carbon emissions increase as a result of their use, renewable sources of energy will be essential. Given the size of the challenge to provide energy security in a sustainable way, it is important to explore the entire spectrum of possible energy sources. Biofuels from plants and algae have the potential to offer both a sustainable and carbon-neutral supply, but many hurdles need to be overcome before this potential is realised. With the critical mass of bioenergy researchers now working in Cambridge, the Bioenergy Initiative has the opportunity to play a major role in tackling these issues.

For more information, please contact the authors Professor Alison Smith (as25@cam.ac.uk) at the Department of Plant Sciences and Dr Paul Dupree (pd101@cam.ac.uk) at the Department of Biochemistry, or visit www.bioenergy.cam.ac.uk/

̽��ֱ��Bioenergy Initiative is bringing biology and engineering together to address the challenge of meeting our future energy needs.

Alison Smith

Algae

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