The actin gene of Hypsibius klebelsbergi (Eutardigrada) – complete sequence and comparison with actin from related and non‐related taxa

Abstract

The actin gene of tardigrades was sequenced and analysed using a k ZAP Express cDNA library from the eutardigrade Hypsibius klebelsbergi previously constructed by us. We obtained the complete actin coding sequence of one isoform (1128 bp; 375 amino acids; MW 41 674 Da) together with parts of the 3¢-and 5¢-UTR region. Comparison of the 12 incomplete actin sequences of Hypsibius dujardini incorporated in GenBank indicates that this H. klebelsbergi actin sequence probably represents the most abundant muscle isoform. Ten of the H. dujardini clones show minor differences in codon usage and identical amino acid compositions to the H. klebelsbergi actin. Only two clones show amino acid variations in one and five positions, respectively, but show identical amino acids at their N-terminus. A considerable similarity between the 5¢-and 3¢-UTR regions of both tardigrade species was recognized. The H. klebelsbergi actin exhibits an overall high sequence similarity to the vertebrate b-actin. A comparison of muscle actins from various vertebrates as well as Ecdysozoa and non-Ecdysozoa revealed a more pronounced similarity of the tardigrade actin to arthropods and annelids and not to nematodes.

EF‐Hand Proteins and the Regulation of Actin‐Myosin Interaction in the Eutardigrade Hypsibius klebelsbergi (Tardigrada)

“…holes (Dastych et al, 2003) and obtained the complete nucleotide sequence of one actin gene and its deduced amino acid sequence (D'Haese et al, 2011). In continuation of these studies, we herein report data about four EF-hand proteins that trigger by calcium binding the interaction of actin-myosin.…”

“…Biochemical experiments of tardigrades are hampered due to their small size (average approximately 500 μm) and the lack of a convenient culture system to obtain large amounts of animals for protein isolation. We recently constructed a cDNA library of the eutardigrade Hypsibius klebelsbergi (Kiehl et al, ), a species that lives exclusively on glaciers in cryoconite holes (Dastych et al, ) and obtained the complete nucleotide sequence of one actin gene and its deduced amino acid sequence (D'Haese et al, ). In continuation of these studies, we herein report data about four EF‐hand proteins that trigger by calcium binding the interaction of actin–myosin.…”

The Emergence of the TardigradeHypsibius exemplarisas a Model System

“…Studies using this model and the other tardigrade species mentioned above have focused mostly on survival in extreme conditions in the laboratory (Guidetti et al 2011;Horikawa et al 2013;Beltrán-Pardo et al 2015;Fernandez et al 2016;Vasanthan et al 2017), identifying extremotolerance mechanisms (Kondo et al 2015;Hashimoto et al 2016;Boothby et al 2017), development and anatomy and the evolution of development and anatomy Mayer et al 2013;Smith and Jockusch 2014;Gross and Mayer 2015;Hyra et al 2016a,b;Smith et al 2016;Gross et al 2017), taxonomic methods and relationships (Rota-Stabelli et al 2010;Stec et al 2016), sequence comparisons with other species (Förster et al 2009;Mali et al 2010;Christie et al 2011;D'Haese et al 2011;Beltrán-Pardo et al 2013;Hering and Mayer 2014;Mayer et al 2015;Szitenberg et al 2016;Thiruketheeswaran et al 2017;Nelson 2018), and analyses of specific proteins (Bavan et al 2009;Hering et al 2016). Genomic studies are discussed in a section below.…”