(ORDO NEWS) — Raphidocystis contractili protists are able to move their processes at a record speed for cells.
The Japanese researchers were able to explain how they do this, as well as identify the proteins and genes involved in such a rapid process.
According to the authors of the work, R. contractili cells may turn out to be excellent sensory systems that track changes in the environment.
The protists Raphidocystis contractilis belong to the sunflower group ( Heliozoa ). These unicellular organisms live in sea water and have ray-like processes – axopodia.
Each axopodium contains tubulin protein subunits that form microtubules. In response to external stimuli, R. contractilis is able to withdraw its axopodia at a record speed for a cell.
However, the mechanism underlying this extremely fast movement has so far remained a mystery. Now scientists from Okayama University (Japan) have been able to explain it and offer a practical application.
The authors began their work with immunolabeling of tubulin, as well as with observations of its condition before and after axopodium contraction.
It turned out that prior to the shortening of the process, the tubulin subunits were systematically located along the entire length of the axopodia, but after that they were concentrated on the cell surface.
This led scientists to believe that when the axopodia are quickly withdrawn, the microtubules instantly disintegrate into individual protein subunits.
But the degradation of microtubules is usually not a rapid phenomenon. Therefore, scientists suggested that in R. contractilis, microtubules simultaneously split in several places.
To confirm their hypothesis, they began looking for proteins and genes involved in the instantaneous breakdown of tubulin.
To do this, the researchers conducted transcriptome sequencing – this is an analysis of genes expressed in a cell at a certain time. As a result, it was possible to identify about 32 thousand genes.
Homological and phylogenetic analysis of this set revealed several genes and their proteins involved in the destruction of microtubules.
Among them, the most important were katanin p60, kinesin, and calcium signaling proteins. Catanine p60 is involved in the control of the length of the axopodia.
Kinesin-13 is the main protein that destabilizes microtubules. Signaling proteins react to the influx of calcium ions into the cell and induce axopodium withdrawal.
According to the researchers, the R. contractilis axopodia may function as a sensitive sensor, detecting the smallest changes in the environment, such as the presence of heavy metal ions or anticancer drugs.
Contact us: [email protected]