On September 2009, from the French port of Lorient went 36-meter schooner Tara, setting off a large-scale project for the study of marine plankton communities Tara Oceans. For three and a half years, an international team of scientists collected more than 35,000 samples of living organisms, trying to build a holistic view of life in the upper layers of the oceans. The first results of the study were presented in five papers published in a special issue of the publication Science. They include a catalog of over 40 million microbial genes, most of which were previously unknown and 5000 genetic types of viruses.
Surprisingly, the amount of information has been obtained on the basis of the analysis of only 600 specimens. Microscopic plankton produces half of the oxygen that forms on our planet in the process of photosynthesis. But while science knows about these organisms is very little. Until now, 4350 described species of microalgae and protozoan species 1350 5500 species of small marine animals. But the 1st data of the new genetic analysis show that the actual biological diversity in every of these groups can be from three to 9 times more of our modern ideas. With viral communities difference may be even more pronounced.
So from 5000 viral populations found in the first processed samples, only 39 are similar to the previously described species. It’s not surprising that the oceans contain a large number of organisms with a huge genetic diversity – says ecologist Jack Gilbert Jack Gilbert Argonne National Laboratory. More importantly, as a genetic database can be used to forecast the ecological relationships between microbes and how marine ecosystems respond to environmental change. Instead of studying one type of organism or molecule, we are trying to understand the behavior of the whole system – adds the project director Eric Karsenti (Eric Karsenti), from the European Molecular Biology Laboratory in Heidelberg.
Scientists have learned all the DNA fragments from the organisms found in the samples. They are then sequenced and analyzed the genetic sequences using special software to determine how many different types fell into their hands. This approach, called metagenomics allows you to draw conclusions about the functions of certain genes, even if the mother’s body cannot be isolated or produced in the laboratory. The analysis allowed us to determine the degree of impact on the marine ecosystems of various environmental factors. So, it turned out that the temperature affects the structure of microbial communities is much stronger than the salinity and oxygen content.
But the most interesting is that the researchers used genetic data to predict the interactions between individual organisms. For example, by analyzing the genes they predicted a symbiotic relationship of sorts Symsagittifera worm and kind of mirage Tetraselmis and then confirm their suspicions, finding worms in single-celled organisms with a microscope. In just 3 and a half years, which lasted expedition, it was attended by more than 160 scientists, supported by three dozen research centers and governmental organizations from Europe, Asia and America assistance to the project is even American and European Space Agency. Ahead of the side has a lot of work, because most of the data just waiting for analysis. But even the results that have already laid out in free access, open up vast prospects for Bioinformatics specialists worldwide. In addition, information on the composition and interaction of plankton communities can be compared with oceanographic models for a better understanding of global processes in the oceans.