Community Research and Development Information Service - CORDIS

Simulating natural light for molecular ecology

The Prochlorococcus is one of the key prokaryote organisms, those with genetic material not enclosed within the cell nucleus, of ocean ecosystems. Cultures of this organism are difficult to grow since sunlight barely reaches these dark, deep-water environments where Prochlorococcus is found. An illumination system was developed that automatically switches between light and dark conditions to simulate the necessary specifications for growing Prochlorococcus.
Simulating natural light for molecular ecology
In recent years, biologists have discovered new means of resolving key ecological problems with the aid of marine biology (molecular biology applied to oceanography). The advances accomplished allow the direct use of molecular probes on field samples in order to evaluate the genetic diversity in marine species or to assess their nutritional status.

One of these recently discovered marine microorganisms, Prochlorococcus grows in areas like the Mediterranean and the Red Sea that are deficient in plant nutrients and throughout which, a large amount of dissolved oxygen exists. It is the tiniest and the most photosynthetic organism on Earth. It has been estimated that it is largely accountable for the primary production of photosynthetic biomass in these areas. It can be easily discriminated and counted by methods of flow cytometry. Furthermore, culture extracts derived from various sites and depths can be isolated and studied in the laboratory. For all these reasons, Prochlorococcus is a great biological model for ecological studies.

Exploiting automatic systems that artificially induce natural environmental conditions is a widely accepted and commonly used method for studying various species, but particularly unicellular microorganisms. Within the framework of this project, an automatic illumination cycler was designed for growing the Prochlorococcus microorganism. The system comprises of a double set of dimmable neon tubes that are computer operated and produce uniform illumination that smoothly alternates from light to dark and vice versa. This illumination mimics quite effectively natural solar light radiation with peak values almost at 1000 micro-mol quanta m-2 s-1.

Previous methods used square signals (no light/full light) to study the biological characteristics (growth, cell cycle, photosynthesis, gene expression) of Prochlorococcus. Compared to these, this new device is better suited and far better capable of inducing a well synchronised, exponentially growing Prochlorococcus culture. This system may also be extended and applied to all research or industry fields that are performing thorough studies at dual rhythms in vegetal or animal organisms, such as biological clocks.
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