Daily Mail, UK
Wed, 13 Feb 2013 15:35 UTC
U.S. researchers have discovered communities of infinitesimal creatures in our oceans react in unison to changes in their environment.
The links between them are not well understood, but findings suggest the creatures rely on each other to almost the same extent as the different cells in a human body.
As an example, if one set of the microbes were, say, creating energy through photosynthesis, which would then produce carbon dioxide, another set of microbes would somehow know and react - perhaps preparing to absorb the carbon dioxide.
The open sea contains an amazing diversity of extremely tiny organisms called picoplankton, which include relatively simple life forms such as marine bacteria, as well as more complicated organisms.
Microbiologists who study wild marine microbes, as opposed to the lab-grown variety, face enormous challenges in getting a clear picture of the daily activities of their subjects.
To take a look at these creatures in their natural habitat, researchers from the Massachusetts Institute of Technology and the Monterey Bay Aquarium Research Institute used a new method for collecting marine microbes.
Similar to fast photography that stops action, the robotic device 'fixed' each sample so that whatever genes the microbes were expressing at the moment of capture were preserved for later study.
After returning the samples to the lab, researchers used cutting-edge analysis techniques to figure out which genes within the microbes were actively being used at different times of day.
This involved sorting through millions of billions of fragments of genetic material and then assigning each fragment to a specific gene and a specific type of microbe.
In so doing they created a time-lapse montage of the daily labours of a range of microbial species over a two-day period.
'A naturalist like Sir David Attenborough can follow a herd of elk and see how the elk's behavior changes hour to hour, day to day and week to week,' said Edward DeLong, professor of environmental systems at MIT.
'But we haven't been able to observe naturally occurring microbes with that kind of resolution until now.'
Professor DeLong, who is lead author of a paper in the Proceedings of the National Academy of Sciences detailing the research, added: 'We've essentially captured a day in the life of these microbes.
'As little as three years ago, I wouldn't have even have considered it possible to get such a high resolution picture of microbial population dynamics and activity in the "real world".'
The montage showed photosynthetic microbes, which create the oxygen, energy and organic carbon used by the rest of the food web, ramped up their light-utilising activities in the morning and powered those down at night, just as their domestic brethren do in response to light and dark in the lab.
But the underwater scenes also showed something scientists had never seen before.
Some of the genes simultaneously expressed by different species shared the same function - for instance, genes associated with growth or respiration.
Others encoded very different functions, mirroring the varied metabolic capabilities of the disparate species.
The researchers hypothesised that all these microbes were reacting to the same environmental changes, but that different groups of microbes were responding in different ways.
Although the researchers cannot tell exactly which environmental changes the microbes were responding to, they suspect that the different groups of microbes were working together to obtain different types of food.
For example, some picoplankton could have been consuming large organic compounds such as proteins and fats. In the process, they could have produced simpler organic compounds, such as amino acids, which were then released into the surrounding seawater and consumed by other picoplankton.
'These results show a surprising amount of coordination between marine microbes,' said a spokesman for the Monterey Bay Aquarium Research Institute.
'They also suggest that, as in the food webs of larger organisms, many different groups of marine microbes rely on each other to survive on a day-to-day basis.
'This could help explain why so many species of marine microbes are difficult or impossible to grow by themselves in the lab.'