jueves, 14 de febrero de 2013

Could the sea be conscious? Research reveals how tiny plankton behave like a marine 'megamind'

ORIGINAL: Daily Mail
13 February 2013

U.S. researchers find that different forms of picoplankton react as one to environmental changes
Although as different as humans and fungi, the creatures' behaviour was linked

Findings could help researchers understand why some species are impossible to grow in isolation

Vastly different species of sea microbes work together to respond as one to their surroundings as if they have one 'megamind', new research has revealed.

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.

Megamind: Despite the amazing diversity of marine microbes, a new research paper shows that many different groups work together to react in unison to their surroundings
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.

They created a robotic sampling device which dangled beneath the waves to collect samples of one billion microbes every four hours.

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 research vessel drifts near the buoy supporting the Environmental Sample Processor used to collect microbes for the experiment. Inset shows the yellow float with the ESP pressure housing suspended in the water

'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.

Using their robot microbe collecting device, researchers were able to gather samples of one billion microbes every four hours and keep them 'fixed' at the moment of collection.

This meant that whatever genes the microbes were expressing at the moment of capture were preserved for later study in the lab.

Microbes are extraordinarily sensitive to slight environmental changes, altering their gene expression rapidly in response to fluctuations in temperature, light, nutrient availability and other environmental variables.

Because of this, the genes they express tell a story about their habitat and their interactions with it.

In essence, changes in their gene expression provide information on the good times and the bad times they experience.

In a sense, each naturally occurring microbe is a living sensor and the researchers can read the sensors’ outputs by studying their gene expression.

By studying these environmental responses the MIT/MBARI team were able to make completely new findings about the behaviour of the creatures.

'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.

Non-photosynthetic, carbon-eating microbes of very different species displayed synchronised, rapidly varying metabolic gene expression - despite the fact that they came from groups as different as humans and fungi.

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.

'We've essentially captured a day in the life of these microbes': Researchers readying the robotic device connected to a buoy for its two-day sampling journey off the coast of California
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.'

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