BIOMECHANICAL STUDY ON DIFFERENT DIRECTIONS FOR RUNNING JUMPS FOCUSED ON THE TAKEOFF PREPARATION

This study aimed to elucidate the difference in CG parameters from three steps, prejump to takeoff step of the jump motion (running jump), and obtain primary data on takeoff preparation action. Five male jumpers associated with the university track and field department were trained to perform their best at (1) approach run with no takeoff (RUN), (2) jumping as far as possible (long jump [LJ]), and (3) jumping as high as possible (high jump [HJ]), which were recorded using a three-dimensional capture system. As a result, significant differences were observed in not only the takeoff but also the takeoff preparation phase regarding CG parameters, suggesting the need to focus on the takeoff preparation phase as a factor that determines jump direction. Moreover, HJ and LJ suppressed an increase in vertical velocity one step prior, and by takeoff at a lower CG, the athletes allowed for an easier increase in takeoff angle and jump height. However, to resist a decrease in horizontal velocity, LJ transitioned to takeoff in a manner closer to RUN and without changing takeoff preparation as much as that in HJ. Thus, adjusting vertical velocity and height one step before takeoff can influence takeoff angle

The K computer Operations: Experiences and Statistics

AbstractThe K computer, released on September 29, 2012, is a large-scale parallel supercomputer system consisting of 82,944 compute nodes. We have been able to resolve a significant number of operation issues since its release. Some system software components have been fixed and improved to obtain higher stability and utilization. We achieved 94% service availability because of a low hardware failure rate and approximately 80% node utilization by careful adjustment of operation parameters. We found that the K computer is an extremely stable and high utilization system

Quantitation of the neural silencing activity of anion channelrhodopsins in Caenorhabditis elegans and their applicability for long-term illumination

Ion pumps and channels are responsible for a wide variety of biological functions. Ion pumps transport only one ion during each stimulus-dependent reaction cycle, whereas ion channels conduct a large number of ions during each cycle. Ion pumping rhodopsins such as archaerhodopsin-3 (Arch) are often utilized as light-dependent neural silencers in animals, but they require a high-density light illumination of around 1 mW/mm2. Recently, anion channelrhodopsins -1 and -2 (GtACR1 and GtACR2) were discovered as light-gated anion channels from the cryptophyte algae Guillardia theta. GtACRs are therefore expected to silence neural activity much more efficiently than Arch. In this study, we successfully expressed GtACRs in neurons of the nematode Caenorhabditis elegans (C. elegans) and quantitatively evaluated how potently GtACRs can silence neurons in freely moving C. elegans. The results showed that the light intensity required for GtACRs to cause locomotion paralysis was around 1 µW/mm2, which is three orders of magnitude smaller than the light intensity required for Arch. As attractive features, GtACRs are less harmfulness to worms and allow stable neural silencing effects under long-term illumination. Our findings thus demonstrate that GtACRs possess a hypersensitive neural silencing activity in C. elegans and are promising tools for long-term neural silencing

Molecular phylogeny of the rotifers with two Indonesian Brachionus lineages

The rotifer Brachionus plicatilis is an ecologically and commercially important species, and has been studied in various fields such as population dynamics, ecotoxicology and aging. However, recent studies have revealed that the B. plicatilis lineages involve an unknown number of cryptic species, and the group has been regarded as the Brachionus complex. One cause of this complicated taxonomy is the lack of surveys in the tropical zone, which is characterized by enormous species-richness. Accordingly, in this study we collected two Brachionus rotifers from the Sumatra and Sulawesi Islands, Indonesia, and determined their partial nucleotide sequences of mitochondrial DNA cytochrome c oxidase subunit I gene. Subsequently, we constructed molecular phylogenetic trees with fourteen species/lineages from four genera including the two Indonesian rotifers. The two Indonesian Brachionus rotifers were respectively found to be phylogenetically close to B. ibericus and B. rotundiformis. On the other hand, Japanese B. plicatilis was suggested to be phylogenetically closer to B. Manjavacas, which is proposed to be a new species, than to Spanish B. plicatilis. These results imply that the current taxonomy of the Brachionus is problematic, and a major revision is necessary to establish a reliable taxonomy of this group

Quantitation of the neural silencing activity of anion channelrhodopsins in Caenorhabditis elegans and their applicability for long-term illumination

Ion pumps and channels are responsible for a wide variety of biological functions. Ion pumps transport only one ion during each stimulus-dependent reaction cycle, whereas ion channels conduct a large number of ions during each cycle. Ion pumping rhodopsins such as archaerhodopsin-3 (Arch) are often utilized as light-dependent neural silencers in animals, but they require a high-density light illumination of around 1 mW/mm2. Recently, anion channelrhodopsins -1 and -2 (GtACR1 and GtACR2) were discovered as light-gated anion channels from the cryptophyte algae Guillardia theta. GtACRs are therefore expected to silence neural activity much more efficiently than Arch. In this study, we successfully expressed GtACRs in neurons of the nematode Caenorhabditis elegans (C. elegans) and quantitatively evaluated how potently GtACRs can silence neurons in freely moving C. elegans. The results showed that the light intensity required for GtACRs to cause locomotion paralysis was around 1 µW/mm2, which is three orders of magnitude smaller than the light intensity required for Arch. As attractive features, GtACRs are less harmfulness to worms and allow stable neural silencing effects under long-term illumination. Our findings thus demonstrate that GtACRs possess a hypersensitive neural silencing activity in C. elegans and are promising tools for long-term neural silencing

Demonstration of a Light-Driven SO42- Transporter and Its Spectroscopic Characteristics.

In organisms, ion transporters play essential roles in the generation and dissipation of ion gradients across cell membranes. Microbial rhodopsins selectively transport cognate ions using solar energy, in which the substrate ions identified to date have been confined to monovalent ions such as H+, Na+, and Cl-. Here we report a novel rhodopsin from the cyanobacterium Synechocystis sp. PCC 7509, which inwardly transports a polyatomic divalent sulfate ion, SO42-, with changes of its spectroscopic properties in both unphotolyzed and photolyzed states. Upon illumination, cells expressing the novel rhodopsin, named Synechocystis halorhodopsin (SyHR), showed alkalization of the medium only in the presence of Cl- or SO42-. That alkalization signal was enhanced by addition of a protonophore, indicating an inward transport of Cl- and SO42- with a subsequent secondary inward H+ movement across the membrane. The anion binding to SyHR was suggested by absorption spectral shifts from 542 to 536 nm for Cl- and from 542 to 556 nm for SO42-, and the affinities of Cl- and SO42- were estimated as 0.112 and 5.81 mM, respectively. We then performed time-resolved spectroscopic measurements ranging from femtosecond to millisecond time domains to elucidate the structure and structural changes of SyHR during the photoreaction. Based on the results, we propose a photocycle model for SyHR in the absence or presence of substrate ions with the timing of their uptake and release. Thus, we demonstrate SyHR as the first light-driven polyatomic divalent anion (SO42-) transporter and report its spectroscopic characteristics

Porphyrin‐uptake in liposomes and living cells using an exchange method with cyclodextrin

The water‐solubilisation of porphyrin derivatives is very important for biological applications. Although liposomal drug carriers for porphyrin derivatives have shown significant promise in the field of medicinal chemistry (e.g., as sensitisers for photodynamic therapy), it is currently not possible to prepare lipid‐membrane‐incorporated tetraphenylporphyrin (TPP) with a high concentration of TPP using conventional methods. In this study, we have succeeded in preparing lipid-membrane‐incorporated TPP and zinc(II) tetraphenylporphyrin (ZnTPP) from the corresponding TPP or ZnTPP•cyclodextrin complex using the exchange method in lipid‐membranes composed of liposomes. Furthermore, the exchange method allowed for the incorporation of TPP or ZnTPP into the plasma membranes of HeLa cells. However, it was not possible to prepare lipid‐membrane‐incorporated porphyrin derivatives with polar and hydrophilic groups in the meso positions using this exchange reaction.Electronic supplementary information (ESI) available: Experimental procedures, 1H NMR spectra, DLS measurements, cryo-TEM images, phase contrast and fluorescence images. See DOI: 10.1039/c5ra24985This work was supported by JSPS KAKENHI a Grant‐in‐Aid for Scientific Research (B) (Grant No. 25288037) and a Grant‐in‐Aid for Young Scientists (A) (Grant No. 24681028)