Leaf traits of polar willow colonizing in a glacier foreland, Ny-Ålesund, Svalbard

第2回極域科学シンポジウム/第33回極域生物シンポジウム 11月18日（金） 統計数理研究所 3階セミナー室

THE GENERATION OF INTERNAL SOLITARY DISTURBANCES BY GRAVITY CURRENTS IN A TWO-LAYER FLUID

The generation of internal disturbances (solitary bulges and waves) by a gravity current entering a two-layered water has been investigated by means of flow visualization in a 2ｍ water tank. It has been observed that a gravity current evolves into a solitary internal bulge, which eventually leads to the generation of a solitary internal wave. The solitary wave was found to form more effectively when a gravity current head is forced to collapse at a mesh screen placed transversely to the flow direction

WAKES OF A CIRCULAR CYLINDER IN STRATIFIED FLUIDS

The results are reported of a preliminary flow-visualization experiment on the characteristics of two-dimensional wakes of a circular cylinder moving in stratified fluids in the horizontal direction. To summarize the resuits: 1) The development of vortex wakes behind a circular cylinder is suppressed by the stable stratification of ambient fluids. 2) The vortex streets developed initially evolve into a pair of standing vortices as the cylinder moves at critical values of a stratification parameter k for vortex shedding. 3) The formation of internal lee waves dominates the cylinder wakes at low Reynolds numbers.1. Introduction / 2. Experimental methods / 3. Results and discussio

Outer dynein arm light chain 1 is essential for controlling the ciliary response to cyclic AMP in Paramecium tetraurelia

The individual role of the outer dynein arm light chains in the molecular mechanisms of ciliary movements in response to second messengers, such as Ca(2+) and cyclic nucleotides, is unclear. We examined the role of the gene termed the outer dynein arm light chain 1 (LC1) gene of Paramecium tetraurelia (ODAL1), a homologue of the outer dynein arm LC1 gene of Chlamydomonas reinhardtii, in ciliary movements by RNA interference (RNAi) using a feeding method. The ODAL1-silenced (ODAL1-RNAi) cells swam slowly, and their swimming velocity did not increase in response to membrane-hyperpolarizing stimuli. Ciliary movements on the cortical sheets of ODAL1-RNAi cells revealed that the ciliary beat frequency was significantly lower than that of control cells in the presence of ≥1 mM Mg(2+)-ATP. In addition, the ciliary orientation of ODAL1-RNAi cells did not change in response to cyclic AMP (cAMP). A 29-kDa protein phosphorylated in a cAMP-dependent manner in the control cells disappeared in the axoneme of ODAL1-RNAi cells. These results indicate that ODAL1 is essential for controlling the ciliary response by cAMP-dependent phosphorylation

Identifying the chloroperoxyl radical in acidified sodium chlorite solution.

The present study identified the active radical species in acidic sodium chlorite and investigated the feasibility of quantifying these species with the diethylphenylenediamine (DPD) method. Electron spin resonance (ESR) spectroscopy was used to identify the active species generated in solutions containing sodium chlorite (NaClO2). The ESR signal was directly observed in an acidified sodium chlorite (ASC) aqueous solution at room temperature. This ESR signal was very long-lived, indicating that the radical was thermodynamically stable. The ESR parameters of this signal did not coincide with previously reported values of the chlorine radical (Cl●) or chlorine dioxide radical (O = Cl●-O and O = Cl-O●). We refer to this signal as being from the chloroperoxyl radical (Cl-O-O●). Quantum chemical calculations revealed that the optimal structure of the chloroperoxyl radical is much more thermodynamically stable than that of the chlorine dioxide radical. The UV-visible spectrum of the chloroperoxyl radical showed maximum absorbance at 354 nm. This absorbance had a linear relationship with the chloroperoxyl radical ESR signal intensity. Quantifying the free chlorine concentration by the DPD method also revealed a linear relationship with the maximum absorbance at 354 nm, which in turn showed a linear relationship with the chloroperoxyl radical ESR signal intensity. These linear relationships suggest that the DPD method can quantify chloroperoxyl radicals, which this study considers to be the active species in ASC aqueous solution