Author: Dr Paulo Rocha -

The findings of the paper:

Algae are the world's most important “plants”. They play a crucial role in the air we breathe, food we eat and pharmacological drugs we take including for cancer. Yet there is only so much we know about these amazing ‘plants’. One reason is because there are no methods to actually decode algae behaviours and concomitant signaling mechanisms.

Hence, my group together with collaborators from Portugal and The Netherlands have demonstrated that contrary to what expected, Diatoms, a microalgae type, do talk among each other! And they talk a lot!

We demonstrated that a population of diatoms under darkness show quasi-periodic electrical oscillations, or intercellular waves. The origin of this behaviour is paracrine signalling between the diatoms induced by changes in their physicochemical environment.

Why this is important:

Diatoms form the basis of many marine food webs and play a key ecological role in the bio-geochemical cycling of carbon and silica. They play a crucial role in the air we breathe, food we eat and pharmacological drugs we take including for cancer. Decoding their communication is hence a step forward into understanding world challenges such as climate change and harmful algae blooms leading to per example food toxicity.

How we found this out:

A population of Pseudo-nitzschia fraudulenta under light is electrically inert. Photosynthesis is self-contained within the chloroplasts of diatoms and does not lead to changes in the extracellular field potential. However, in complete darkness, we demonstrate that diatoms become electrically active. We measured diatoms’ electrical activity using sensitive and low impedance multi electrode arrays (MEAs). In our recording system, we note that in a time span of hours their response evolves from weak, sporadic, uncorrelated events of single diatoms, to strong quasi-periodic oscillations synchronized by the whole diatom population.

The synchronized quasi-periodic signals shows a 1/f1.5 frequency dependence which is normally assigned to a diffusion process. These intercellular waves last for days and are due to paracrine cell-cell signaling. Under stress, such as light deprivation, and, probably by a temperature rise, diatoms start to communicate. The cell-cell signaling is a feedback, or survival, mechanism that counteracts changes in the physicochemical environment. The messenger is likely to be related to Ca2+ ions as spatiotemporal changes in their concentration match the characteristics of the intercellular waves. This conclusion is supported by using the inhibitor GdCl3 which specifically inhibits Ca2+ stretch-activated channels. The transport of Ca2+ ions to the extracellular medium is blocked by the inhibitor and the intercellular waves disappear.

Single cell recordings such as patch clamp and fluorescent-based techniques do not allow the observation of Ca2+ exchange with the exterior, as Ca2+ quickly dissipates into the extracellular environment. However, our work on extracellular recordings of a large diatom population permits the monitoring of ions exchange between diatoms. As such, our extracellular recording approach provides a powerful indicator for the development of algae blooms and to probe ecological and physiological stress conditions in diatom populations.

What this means for the planet:

This project will open a new page in the understanding of algae signaling and enable novel sensing technologies to predict the development of algae blooms and of an extensive range of stress-induced alterations in the aquatic ecosystem. This interdisciplinary work involving the fields of bioelectronics and biology has strong scientific and technological implications for probing ecological and physiological stress conditions in phytoplankton populations.

Water companies will in a near future benefit from a control technology able to predict and impair harmful and toxic algae blooms.  General population by (1) predicting and avoiding amnesic shellfish poisoning (major consequence of algae blooms) and by enabling accurate studies on climate change.

What this means for you:

This could ultimately result in your water bills decreasing and you will drink more natural water that has been subjected to fewer chemical treatments and diminish amnesic shellfish poisoning, a rising problem in coastal countries.

My role in this research included/I worked with:

This research is a collaborative effort between the Universities of Bath, Delft University of Technology in The Netherlands, Instituto Gulbenkian de Ciência and the Centre for Marine Sciences in Portugal.

What this research could lead on to:

Now we know more about the behaviour of diatoms we can develop a technology specifically able to

  1. understand how these cells adapt to sudden changes in their physicochemical environment,
  2. sense and predict the development of algae blooms in water reservoirs
  3. translate an extensive range of stress-induced alterations in the aquatic ecosystem.

Posted in: Department of Electronic & Electrical Engineering, Research

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