Chara australis has giant cells ideal for studying cell biology

Chara australis has giant cells ideal for studying cell biology © Akira Oikawa

A research team at the RIKEN Plant Science Center have uncovered fundamental cell processes by studying 125 different metabolites within the giant cells of the freshwater algae Chara australis.

Chemical reactions within our cells produce intermediate and end products in the form of small molecules called metabolites. These play important roles in the regulation of critical biological processes, including growth, development and chemical defence.

Metabolomics is the systematic study of these unique chemical footprints, and involves identifying and characterizing the many metabolites found in a cell, tissue, organ or organism, as well as their production, distribution and dynamics,” explains Kazuki Saito from the RIKEN Plant Science Center.

The molecules involved in producing and converting different metabolites are known as enzymes. These are often found within different cell compartments called organelles. Biologists have always assumed that the situation is similar for metabolites themselves, but until now none had demonstrated this comprehensively.

Saito says that understanding the dynamics of metabolites within single organelles represents an enormous technical challenge, because of the tiny sizeof these structures in most cells. To get around this, he and his colleagues turned to a species of algae called C. australis, whose cells can grow up to a whopping 20cm long.

Because of their gigantic size and volume, these “internodal” cells are widely used to study various aspects of cell biology. The researchers purified single vacuoles, a type of organelle, from internodal cells. They then used sophisticated metabolomic techniques to determine what was going on with the metabolites in the vacuole and the cell cytoplasm.

Plant cell structure

Plant cell structure ©LadyofHats (Mariana Ruiz)

The team detected 125 known metabolites, and showed that they fluctuated independently in the vacuole and cytoplasm under different light conditions. This suggests that metabolites are spatially regulated within the cell and move between the vacuole and the cytoplasm according to conditions.

“Ours is the first study to confirm specific compartmentalisation of metabolites in a single vacuole from a single cell,” says Saito. The findings shed light on some important aspects of cell metabolism.

For further information contact:

Dr Kazuki Saito
RIKEN Plant Science Center, Japan