Biology News & Research

11 May, 2011

Can evolutionary adaptations be reversed? It’s a question that’s intrigued scientists since the publication of The Origin of Species. In the late 19th century, paleontologist Louis Dollo argued that evolution could not retrace its steps to reverse complex adaptations — a hypothesis known as Dollo's law of irreversibility.

Teams investigating the hypothesis have found various parts of the jigsaw, but putting them together has proved difficult, especially as some seemed to conflict.

“In 2003, scientists showed that some species of insects have gained, lost and regained wings over millions of years. But a few years later, a different team found that a protein that helps control cells' stress responses could not evolve back to its original form,” summed up Anne Trafton of MIT.

Will altering the question get us somewhere closer to an answer? Jeff Gore, assistant professor of physics at MIT, says the critical question to ask is not whether evolution is reversible, but under what circumstances it could be. "It's known that evolution can be irreversible. And we know that it's possible to reverse evolution in some cases. So what you really want to know is: What fraction of the time is evolution reversible?" he says.

Hi and his students combined a computational model with experiments on the mutations in bacteria which confer resistance to certain key antibiotics. They found that “a very small percentage of evolutionary adaptations in a drug-resistance gene can be reversed, but only if the adaptations involve fewer than four discrete genetic mutations”.

Gore says his team's results offer support for Dollo's law, but with some qualifications.

"It's not that complex adaptations can never be reversed," he says. "It's that complex adaptations are harder to reverse, but in a sense that you can quantify."

The study may also go some way to explaining why humans still have an appendix, despite it being no longer needed. "You can only ever really think about evolution reversing itself if there is a cost associated with the adaptation," Gore says. "For example, with the appendix, it may just be that the cost is very small, in which case there's no selective pressure to get rid of it."

Read more on the MIT website

Every yearat the ASE Annual Conference, the Nucleus Biology Group hosts a day of talks, 'Biology in the Real World', bringing together the latest in biology research across a spectrum of different topics.

In 2011 the series of talks focused on 'Biology in the Real World: Biologists Today and Tomorrow'. We've gathered together the slides from the presentations, which are now available from the Society of Biology website.

We particulary recommend Dr Jen Bromley's fascinating talk about the future of biofuels, and the role of the plant cell wall, and Dr Sandy Knapp's excellent discussion of the role of taxonomy in the 21st century. 

Download the slides.

The ASE Annual Conference, the leading science education CPD event of the year, is open to everyone with an interest in science education - ASE members and non-members. It attracts over 3000 science educators from all phases of science education who can choose from over 400 talks, workshops, seminars and booked courses over four inspiring days.

A similar series of talks will be held at next January's conference, with a theme of 'competition and success'.

Photosynthesis has evolved over millions of years - so is it possible for scientists to improve on it? Teams of scientists from a range of different disciplines from both the US and the UK are working to make photosynthesis more efficient.

Professor Janet Allen, Director of Research at BBSRC, said "Photosynthesis has evolved in plants, algae and some other bacteria and in each case the mechanism does the best possible job for the organism in question. However, there are trade-offs in nature which mean that photosynthesis is not as efficient as it could be - for many important crops such as wheat, barley, potatoes and sugar beet, the theoretical maximum is only 5%, depending on how it is measured. There is scope to improve it for processes useful to us, for example increasing the amount of food crop or energy biomass a plant can produce from the same amount of sunlight. This is hugely ambitious research but if the scientists we are supporting can achieve their aims it will be a profound achievement."

Some of the scientists will be focusing improving the efficiency of the 'bottleneck' enzyme RuBisCO. By attempting to transfer parts from algae and bacteria into plants, the researchers hope to make the environment in the plants' cells around RuBisCO richer in carbon dioxide which will allow photosynthesis to produce sugars more efficiently.

The CAPP team explains

"In most plants, growth rate is limited by the rate at which carbon dioxide from the atmosphere is taken up and converted to sugars in the process of photosynthesis. The enzyme responsible for the first step in this process, Rubisco, does not work at its potential maximum efficiency at the current levels of carbon dioxide present in the atmosphere. If levels were much higher, photosynthesis would be faster and plants would grow faster. This speeding-up of photosynthesis will happen naturally over the next fifty years or so as atmospheric carbon dioxide levels rise due to human activities. However, there is an immediate requirement for increased crop productivity to provide food for the rising population of the planet. Our project addresses this problem. We are studying a mechanism present in tiny green algae that results in high concentrations of  carbon dioxide inside their photosynthesising cells (called a Carbon Concentrating Mechanism, or CCM), enabling Rubisco to work at maximum efficiency. We have recently discovered important new information about this mechanism, and we have invented new and rapid methods to discover algal genes that contribute to it. We have two complementary and parallel aims. First, we will apply our new methods to identify all of the genes required by the algae to achieve high concentrations of carbon dioxide inside the cells, and we will discover exactly how these genes work. Second, we will transfer the most important genes into a plant, and study whether the same CCM can be recreated inside a leaf. If it can, we expect that our experimental plant will have higher rates of photosynthesis and hence a higher rate of growth than normal plants. This work will provide new insights into how plants and algae acquire and use carbon dioxide from the atmosphere, of great importance in predicting and coping with the current rapid changes in the atmosphere and hence in climate. The work will also contribute to strategies to increase global food security, because it will indicate new ways in which crop productivity can be increased."

See their website at: http://mudshark.brookes.ac.uk/CAPP

They feign sick, they're shy, they call in others to fight on their behalf  when attacked, and what's more, they trick others into mating with them. In fact, we have to conclude that plants are more like humans than we might think.

Take a look at the New Scientist gallery of sneaky cheating plants.

How far is cell-cell communication conserved between animals and plants? The answer may be that it's much further than we sometimes think.

New research from a team of scientists in Portugal reveals that pollen, the organ that contains the plant male gametes, communicate with the pistil, their female counterpart, using a mechanism commonly observed in the nervous system of animals. The growth of pollen tubes is controlled by, among other things, a rare aminoacid, D-serine (D-Ser). Both D-Ser and GLRs are key molecular players in cell-cell communication in the animal central nervous systems, at various levels: they play a central role in memory and learning processes in the brain, and have been implicated in a wide range of neurodegenerative diseases such as multiple sclerosis, Alzheimer, Huntington's disease and others. The research of the Portuguese scientists suggests that D-serine, produced in the female sexual organs of the plant may have a role in guiding pollen tubes to their final target.

Find out more 

Ask the average person about how plants contribute to health, and you'll probably get two responses - firstly, a mention of the nutritional value of fruit and veg, and secondly, a vague memory of the role of plant compounds as medicines.

But could plants also help deliver vaccines? Would staying healthy be easier if, rather than getting a vaccine through a jab in the arm, you simply ate a banana, a potato, or a tomato?

Getting vaccines out across the world and administering them safely can be a difficult business. Researchers searching for an easier and affordable means of immunization had the idea of using fruit and vegetable plants as factories for synthesizing vaccines, known as ‘‘edible vaccines’’.

An article by researchers Monika Sharma and Bhumika Soods describes edible vaccines as follows: "Invented by Charles J. Arntzen (Biodesign institute, Arizona State University) these subunit vaccines are made up of antigens that can be grown in genetically modified plants and delivered through the edible parts of the plant (Arntzen 1997). They do not contain the genes responsible for pathogenesis, making them safe as they can generate an immune response in the body without causing disease. Edible vaccines are likely to
overcome the hurdles posed by traditional vaccines, as they can be delivered without needles, do not require refrigeration and can be made, less expensively, right in the area in which they will be delivered."

But, as the researchers state, getting ideas from the lab to the real world is not a straight-forward journey: "Though the road ahead seems promising, there are several constraints which restrict the success and public acceptability of these vaccines. These include problems of choice of plants, storage, delivery, dosage, safety, public perception, quality control and licensing."

What do you think? Would you want to see vegetables that can deliver vaccines into your body.

Richard P Grant blogs on the question here: http://blog.the-scientist.com/2011/03/15/a-banana-a-day/

25th February 2011

Stunning photos and an inspiring resource!

A National Geographic photographer set down his quadrat in a Metrosiderous tree in the South Pacific isalnd of Mo'orea, and photographed the 58 species he found living, crawling and flying within it. The team found 7 plant and fungus species, 2 reptiles and 49 arthropods.

National Geographic photographer David Liittschwager photographed this Metrosiderous tree and all 58 species he found crawling, flying, or taking root in it. He and a team of scientists accounted for 49 arthropods, 2 reptiles, and 7 plant and fungus species.

The forests of Mo'orea are a combination of species introduced by the Polynesians and invasives introduced by European settlers, with a few scattered native species.

The researchers hope that Mo'orea, whose coral towers have crumbled to dust under the attacks of the 'crown of thorns' starfish, could eventually serve as a model for understanding how ecosystems respond to stresses such as invasive species, climate change, and pollution.

http://bit.ly/gpDRPn

23rd February 2011

The Wellcome Image Awards 2011 is all about inspiring images - inspiring both scientifically and artistically.

The SAPS team was particularly impressed by one photograph taken using a confocal microscope, showing gene expression and cell division in plants, taken by two plant scientists at the University of Cambridge Department of Plant Sciences and the Scottish Crop Research Institute.

The image shows the expression of different fluorescent proteins in the stem of a thale cress seedling (Arabidopsis thaliana). Arabidopsis is the standard 'model plant' for studying plant biology, and was the first plant to have its genome sequenced. The middle of the image shows a region of high cell proliferation, which drives the growth and branching of the seedling.

21st Feb, 2011

Plants are inspiring new classes of structure, designed to twist, bend, stiffen and even heal themselves, through collaborations between plant scientists and mechanical engineers.

Mimosa Pudica, the 'sensitive plant', is famous for folding its leaves back when touched. The movement is achieved through osmosis: touch triggers water to leave certain cells, and to enter others, with the result that the leaves fold inwards. Researchers are studying how plants change shape, and working to replicate the mechanisms in artificial cells. Today, their artificial cells are palm-size and larger, but the teams are working to shrink them down, using microstructures and nanofibers. They're also exploring how to replicate the mechanisms by which plants heal themselves.

Read more about it in Science Daily.

From Scientific American

The Earth's tallest trees, California redwoods, rely on characteristic coastal fog to reach their towering heights—and that fog may be diminishing, according to new research.

Read more at: http://www.scientificamerican.com/article.cfm?id=fog-that-nourishes-california-redwoods-declining