National Academy of SciencesActa Medica Okayama0027-84242020Insights into the evolution of regulated actin dynamics via characterization of primitive gelsolin/cofilin proteins from Asgard archaea11733ENCanerAkılInstitute of Molecular and Cell Biology, Agency for Science, Technology and ResearchLinh T.TranResearch Institute for Interdisciplinary Science, Okayama UniversityMagaliOrhant-PriouxCytomorphoLab, Interdisciplinary Research Institute of GrenobleYohendranBaskaranaInstitute of Molecular and Cell Biology, Agency for Science, Technology and ResearchEdwardManseraInstitute of Molecular and Cell Biology, Agency for Science, Technology and ResearchLaurentBlanchoinCytomorphoLab, Interdisciplinary Research Institute of GrenobleRobert C.RobinsoncResearch Institute for Interdisciplinary Science, Okayama UniversityAsgard archaea genomes contain potential eukaryotic-like genes that provide intriguing insight for the evolution of eukaryotes. The eukaryotic actin polymerization/depolymerization cycle is critical for providing force and structure in many processes, including membrane remodeling. In general, Asgard genomes encode two classes of actin-regulating proteins from sequence analysis, profilins and gelsolins. Asgard profilins were demonstrated to regulate actin filament nucleation. Here, we identify actin filament severing, capping, annealing and bundling, and monomer sequestration activities by gelsolin proteins from Thorarchaeota (Thor), which complete a eukaryotic-like actin depolymerization cycle, and indicate complex actin cytoskeleton regulation in Asgard organisms. Thor gelsolins have homologs in other Asgard archaea and comprise one or two copies of the prototypical gelsolin domain. This appears to be a record of an initial preeukaryotic gene duplication event, since eukaryotic gelsolins are generally comprise three to six domains. X-ray structures of these proteins in complex with mammalian actin revealed similar interactions to the first domain of human gelsolin or cofilin with actin. Asgard two-domain, but not one-domain, gelsolins contain calcium-binding sites, which is manifested in calcium-controlled activities. Expression of two-domain gelsolins in mammalian cells enhanced actin filament disassembly on ionomycin-triggered calcium release. This functional demonstration, at the cellular level, provides evidence for a calcium-controlled Asgard actin cytoskeleton, indicating that the calcium-regulated actin cytoskeleton predates eukaryotes. In eukaryotes, dynamic bundled actin filaments are responsible for shaping filopodia and microvilli. By correlation, we hypothesize that the formation of the protrusions observed from Lokiarchaeota cell bodies may involve the gelsolin-regulated actin structures.No potential conflict of interest relevant to this article was reported.National Academy of Sciences.Acta Medica Okayama0027-8424112392015Identification of the VERNALIZATION 4 gene reveals the origin of spring growth habit in ancient wheats from South AsiaE5401E5410ENNestorKippesJuan M.DebernardiHans A.Vasquez-GrossBala A.AkpinarHikmentBudakKenjiKatoShiaomanChaoEduardAkhunovJorgeDubcovskyWheat varieties with a winter growth habit require long exposures to low temperatures (vernalization) to accelerate flowering. Natural variation in four vernalization genes regulating this requirement has favored wheat adaptation to different environments. The first three genes (VRN1–VRN3) have been cloned and characterized before. Here we show that the fourth gene, VRN-D4, originated by the insertion of a ∼290-kb region from chromosome arm 5AL into the proximal region of chromosome arm 5DS. The inserted 5AL region includes a copy of VRN-A1 that carries distinctive mutations in its coding and regulatory regions. Three lines of evidence confirmed that this gene is VRN-D4: it cosegregated with VRN-D4 in a high-density mapping population; it was expressed earlier than other VRN1 genes in the absence of vernalization; and induced mutations in this gene resulted in delayed flowering. VRN-D4 was found in most accessions of the ancient subspecies Triticum aestivum ssp. sphaerococcum from South Asia. This subspecies showed a significant reduction of genetic diversity and increased genetic differentiation in the centromeric region of chromosome 5D, suggesting that VRN-D4 likely contributed to local adaptation and was favored by positive selection. Three adjacent SNPs in a regulatory region of the VRN-D4 first intron disrupt the binding of GLYCINE-RICH RNA-BINDING PROTEIN 2 (TaGRP2), a known repressor of VRN1 expression. The same SNPs were identified in VRN-A1 alleles previously associated with reduced vernalization requirement. These alleles can be used to modulate vernalization requirements and to develop wheat varieties better adapted to different or changing environments.No potential conflict of interest relevant to this article was reported.National Academy of Sciences.Acta Medica Okayama0027-8424112272015Solid-liquid critical behavior of water in nanopores82218226ENKenjiMochizukiKenichiroKogaNanoconfined liquid water can transform into low-dimensional ices whose crystalline structures are dissimilar to any bulk ices and whose melting point may significantly rise with reducing the pore size, as revealed by computer simulation and confirmed by experiment. One of the intriguing, and as yet unresolved, questions concerns the observation that the liquid water may transform into a low-dimensional ice either via a first-order phase change or without any discontinuity in thermodynamic and dynamic properties, which suggests the existence of solid|liquid critical points in this class of
nanoconfined systems. Here we explore the phase behavior of a model of water in carbon nanotubes in the temperature|pressure|diameter space by molecular dynamics simulation and provide unambiguous evidence to support solid|liquid critical phenomena of nanoconfined water. Solid|liquid first-order phase boundaries are
determined by tracing spontaneous phase separation at various temperatures. All of the boundaries eventually cease to exist at the critical points and there appear loci of response function maxima, or the Widom lines, extending to the supercritical region. The finite-size scaling analysis of the density distribution supports the
presence of both first-order and continuous phase changes between solid and liquid. At around the Widom line, there are microscopic domains of two phases, and continuous solid|liquid phase changes
occur in such a way that the domains of one phase grow and those of the other evanesce as the thermodynamic state departs from the Widom line.No potential conflict of interest relevant to this article was reported.