Scientists have long been fascinated by tardigrades, microscopic creatures that are capable of withstanding extreme environmental conditions, including desiccation, freezing, and radiation, including in outer space. To survive, tardigrades are able to enter a reversible state of suspended animation known as cryptobiosis. The molecular mechanisms governing cryptobiosis are mostly unknown.
Now, a team of researchers from the Centre of Nanomaterials and Biotechnology at the Faculty of Science of Jan Evangelista Purkyne in Usti nad Labem, tightly collaborating with colleagues from the Centre for Genomic Regulation in Barcelona, Spain, and from the Adam Mickiewicz University in Poznań, Poland, has made an important contribution in unraveling the molecular composition of the tardigrade microtubule cytoskeleton. Tubulins, its building blocks, are crucial in many cellular processes, and the researchers hypothesized that they might play a key role in the morphological changes associated with successful cryptobiosis.
In a new study published in the journal Scientific Reports, the researchers used bioinformatic analyses to identify and characterize tubulin proteins in eight different species of tardigrades. “We found three α-, seven β-, one γ-, and one ε-tubulin isoform in tardigrades,” said lead author Dr. Stanislav Vinopal. “To verify our results, we isolated identified tubulin coding sequences from a laboratory tardigrade, Hypsibius exemplaris, and overexpressed them in mammalian cultured cells, and all tardigrade tubulins were localized as expected, either to the microtubules or to the centrosomes. The identification of a functional ε-tubulin, clearly localized to centrioles, is attractive, especially from the phylogenetic point of view, since the phylogenetic position of Tardigrades within Ecdysozoa is not settled yet.” These findings suggest that tardigrades are part of the Panarthropoda clade, as some groups of Arthropoda still possess δ- and ε-tubulins, which phylogenetically close Nematoda lost.
“This study represents an important step forward in the research on tardigrade cytoskeleton, which should increase our understanding of the molecular mechanisms underlying tardigrade cryptobiosis,” said Bc. Kamila Novotná Floriančičová, the co-first author of the paper. “We hope that our findings will help pave the way for further research into these fascinating creatures and their ability to survive in some of the harshest environments.”
The study, “Phylogenetic and functional characterization of water bears (Tardigrada) tubulins,” was funded by the SGS grant UJEP-SGS-2021-53-003-2.