The absorption of metals

Another side to the research on Chlamydomonas reinhardtii at ULg: the homeostasis of metals. Homeostasis is the capacity of a living being to maintain the balance of its internal environment. "All living organisms need metals such as zinc, manganese, iron or copper, to live,” explains Marc Hanikenne from the Plant Cell Biology Laboratory, “but if there isn’t a good balance and the physiological limits are not respected, the metals can be toxic for the organism”. This researcher attempted to unravel the mechanisms used by Chlamy to regulate this supply in metals. “The homeostasis of metals involves transport through the membrane of the cell through proteins,” explains Marc Hanikenne. “Sometimes, there are ten or fifteen genes that code for very similar proteins. Working on a unicellular being allows us to dissect the role of each protein more easily”. The evolutionary aspect particularly interests this researcher: “There are also plant and animal characteristics in the way in which Chlamy manages the balance of its metals. This can help us to understand the evolution of certain mechanisms associated with the absorption of metals during the adaptations of organisms to their environment”.

It is thanks to a computer program that Marc Hanikenne was able to spot the genes involved in the homeostasis of metals in Chlamydomonas reinhardtii. By making a comparison between similar genes present in other species, he was able to formulate hypotheses on the way they function, confirmed by experiments.

A better understanding in the area of the absorption of metals by plants, thanks to a very simple being like Chlamy, will eventually lead to an improvement in nutritional quality. Indeed, many people are lacking in iron and zinc, often due to a diet too poor in metals. If we manage to identify the genes associated with harnessing metals, plants that absorb certain metals more efficiently could be created and thus make up for the nutritional deficiencies of the population.

The absorption capacity of plants is also of interest in the domain of soil remediation. Plants store toxic metals such as cadmium, lead, aluminium and mercury. They possess detoxification mechanisms which allow them to store these heavy metals without any problem. Some plants grow naturally on sites polluted by these metals. The study of genes that code for the proteins necessary for the absorption of metals in Chlamy provide new information on these mechanisms. One step further towards the creation of genetically modified plants capable of soil decontamination.