![]() ![]() It was found in the epidermis and tissues exposed to mechanical stress and might help resist extreme conditions 28. Cytotardin does not form scaffold-like structures throughout the cell but belt-like filaments 28. ![]() In tardigrades, the cytoplasmatic role of IFs was substituted by a novel lamin-derived protein Cytotardin 28. The presence of an exoskeleton providing mechanical support might cause the loss of cytoplasmic IFs in the arthropod lineage 26, 27. Interestingly, Panarthropoda generally possess microtubules and actin filaments but lack cytoplasmic intermediate filaments (IFs) 26. Although each cytoskeletal filament type has different mechanical properties, dynamics, and biological roles, the systems are interrelated 25. It consists of three prominent protein filament families-actin, intermediate filaments and microtubules. The cytoskeleton provides a system for cellular movement and shape changes. Despite mounting molecular evidence, the phylogenetic position of the phylum Tardigrada has remained uncertain. Some authors proposed that tardigrades belong to the animal clade Panarthropoda (euarthropods and onychophorans) 20, 21, 22, 23, while others suggested that Tardigrada and Nematoda have a closer phylogenetic relationship than Tardigrada and Arthropoda do 24. The phylogenetic position of the phylum Tardigrada is under discussion. However, underlying molecular mechanisms governing cryptobiosis have only begun to emerge 15, 16, 17, 18, 19. After the return of favorable external conditions, tardigrades undergo a reverse morphological change and enter the active stage of life 11, 14. Cryptobiosis helps tardigrades survive unfavorable environmental conditions, such as those listed above 6, 7, 8, 9, 10, 11, 12, 13. In their tun form, tardigrades enter into cryptobiosis, a state with a barely detectable metabolism 6. Tuns are compacted tardigrade bodies with legs withdrawn inward into the body cavity 3, 4, 5. Several tardigrade species can undergo reversible morphological transformations into so-called tuns 2. Tardigrades are known for their unique ability to withstand extreme environmental conditions, such as desiccation, vacuum, low/high temperatures and radiation. Tardigrades, also called water bears, are microscopic ecdysozoans belonging to the phylum Tardigrada, divided into three classes: well-defined Heterotardigrada, Eutardigrada, and dubious Mesotardigrada 1. Thus, our data support the current placement of tardigrades into the Panarthropoda clade. Although the phylogenetically close Nematoda lost their δ- and ε-tubulins, some groups of Arthropoda still possess them. The presence of a functional ε-tubulin, clearly localized to centrioles, is attractive from a phylogenetic point of view. All tardigrade tubulins were localized as expected when overexpressed in mammalian cultured cells: to the microtubules or to the centrosomes. To verify in silico identified tardigrade tubulins, we also isolated and sequenced nine out of ten predicted Hypsibius exemplaris tubulins. We found three α-, seven β-, one γ-, and one ε-tubulin isoform. Therefore, we analyzed and characterized tardigrade tubulins and identified 79 tardigrade tubulin sequences in eight taxa. The molecular composition of the microtubule cytoskeleton in tardigrades is unknown. We hypothesize that microtubules are necessary for the morphological changes associated with successful cryptobiosis. Tubulins are evolutionarily conserved components of the microtubule cytoskeleton that are crucial in many cellular processes. However, the underlying molecular mechanisms of cryptobiosis are mostly unknown. Several tardigrade species undergo reversible morphological transformations and enter into cryptobiosis, which helps them to survive periods of unfavorable environmental conditions. Once you master naming hydrocarbons from their given structures, it is rather easy to draw a structure from a given name.Tardigrades are microscopic ecdysozoans that can withstand extreme environmental conditions. Other molecules-even with larger numbers of substituents-can be named similarly. Note the comma between the numbers, the hyphen between the numbers and the substituent name, and the presence of the prefix di- before the methyl. The methyl groups are on the second and third C atoms in the chain (no matter which end the numbering starts from), so we would name this molecule 2,3-dimethylbutane. There are two substituents, each of which consists of a single C atom they are methyl groups. ![]() The longest chain has four C atoms, so it is a butane. \): Numerical Prefixes to Use for Multiple Substituents Number of Same Substituent ![]()
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