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Headlines Published on 05 October 2004

Title Unmasking the molecular secrets of marine diatoms

Part animal, part plant, these tiny single-celled algae appear to ignore nature’s biological laws. In their gene mapping efforts, US and European scientists have uncovered an incredibly successful microorganism which could play an important role in climate control and even in the creation of new nanodevices.

The silica shell of diatoms as viewed under an electron microscope © Image: Chris Bowler and Keigo Osada
The silica shell of diatoms as viewed under an electron microscope
© Image: Chris Bowler and Keigo Osada
US and European scientists published this week, in the journal Science, the first ever genomic blueprint of a diatom (Thalassiosira pseudonana), an important member of a large family of microscopic ocean algae. Their findings yielded surprising insight into the way these tiny plant-animal hybrids may be using carbon, nitrogen, fats and silica in order to thrive. And they could offer tantalising hope in the ongoing battle against global warming, say some experts.

Diatoms absorb carbon dioxide – a major greenhouse gas linked to adverse climate change – in amounts comparable to all the world’s tropical rain forests combined, say the scientists behind the project.  This means that they generate around one fifth of the oxygen we breathe and act as a vital carbon sink by drawing carbon dioxide out of the atmosphere and soaking it up in the ocean’s depths.

The sequencing work took place at the US’ Joint Genome Institute (JGI) and was led by Daniel Rokhsar, associate director for computational genomics at JGI, together with US colleagues and a group of molecular biologists, oceanographers and ecologists from around the world. Included in this group was Chris Bowler of the Stazione Zoologica (IT) and the Ecole Normale Supérieure (FR). Diatom research in Bowler’s laboratories is also being funded by the EU’s Fifth Framework Programme project ‘Margenes’.

Evolutionary wonders
“We are interested in finding out what the T pseudonana genome can tell us about why diatoms are so successful in marine environments,” notes Bowler. The scientists also want to investigate how these organisms adapt to their environment, for example to see how gene expression varies at different ocean depths.

Ecologists are not the only ones interested in diatoms. They are also attracting the attention of nanotechnologists, who hope that these algae will teach them how to make minute silica structures – impossible to do using current materials and technology. The scientists also considered the evolutionary implications of this genomic work. Their research provides direct genetic confirmation of a theory that diatoms evolved when a heterotroph, a single-cell microbe, engulfed what scientists say was likely to have been a kind of red alga. The two became one organism and swapped some genetic material to create a new hybrid genome.

According to the international team, the project shows the amazing diversity of life on our planet. Diatoms display features traditionally thought to be restricted to animals and other features thought to be restricted to plants, leading to perhaps a new class of what Bowler calls “plantimals”.

From this US sequencing project and the related EU-funded project, much has been learned about how diatoms perceive their environment and survive in it. What’s more, once the details of silicon metabolism come out, the stage should then be set for nanotechnologists to harness diatom proteins for making nanodevices. Understanding the role of diatoms in global climate control and new products generated through nanotechnology are just two of the important spin-offs from this international project.

Source:  EU project press material

Research Contacts page

More information:

  • Margenes Project (QLRT-2001-01226)
  • T pseudonana sequencing (at JGI)
  • Science journal
  • Diatom EST database
  • Stazione Zoologica
  • Bowler laboratory
  • Fifth Framework Programme (on CORDIS)

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