Medaka piwi is Essential for Primordial Germ Cell Migration

Piwi controls the number of primordial germ cells (PGCs) via protecting maternal mRNA from decay and adult germ stem cell division in Drosophila. In mouse and zebrafish, piwi controls maintenance and differentiation of adult germ stem cell during gametogenesis. Whether piwi plays a role in PGC development of vertebrates remains unsolved. We addressed this issue by using medaka (Oryzias latipes) as a vertebrate model. Molecular cloning, sequence comparison and analyses of genomic organization and chromosome synteny led to the identification in this fish of a single piwi gene, called Opiwi. By RT-PCR analyses and in situ hybridization, the Opiwi transcript is maternally supplied and becomes restricted to PGCs and the central nervous system (CNS). Opiwi knockdown did not prevent PGC formation even in the absence of any somatic structures but did significantly reduce the number of PGCs in vivo and in vitro and affect the distribution of PGCs in developing embryos. Surprisingly, depletion of zygotic Opiwi severely and specifically affected PGC migration. We conclude that Opiwi is required not only for determining the PGC number but also for controlling PGC migration. Our results demonstrate that piwi plays a generally conserved role in germ cell development from Drosophila to vertebrate and a specific role in PGC migration.Piwi controls the number of primordial germ cells (PGCs) via protecting maternal mRNA from decay and adult germ stem cell division in Drosophila. In mouse and zebrafish, piwi controls maintenance and differentiation of adult germ stem cell during gametogenesis. Whether piwi plays a role in PGC development of vertebrates remains unsolved. We addressed this issue by using medaka (Oryzias latipes) as a vertebrate model. Molecular cloning, sequence comparison and analyses of genomic organization and chromosome synteny led to the identification in this fish of a single piwi gene, called Opiwi. By RT-PCR analyses and in situ hybridization, the Opiwi transcript is maternally supplied and becomes restricted to PGCs and the central nervous system (CNS). Opiwi knockdown did not prevent PGC formation even in the absence of any somatic structures but did significantly reduce the number of PGCs in vivo and in vitro and affect the distribution of PGCs in developing embryos. Surprisingly, depletion of zygotic Opiwi severely and specifically affected PGC migration. We conclude that Opiwi is required not only for determining the PGC number but also for controlling PGC migration. Our results demonstrate that piwi plays a generally conserved role in germ cell development from Drosophila to vertebrate and a specific role in PGC migration

Applications of the Adversary Method in Quantum Query Algorithms

In the thesis, we use a recently developed tight characterisation of quantum query complexity, the adversary bound, to develop new quantum algorithms and lower bounds. Our results are as follows: * We develop a new technique for the construction of quantum algorithms: learning graphs. * We use learning graphs to improve quantum query complexity of the triangle detection and the $k$-distinctness problems. * We prove tight lower bounds for the $k$-sum and the triangle sum problems. * We construct quantum algorithms for some subgraph-finding problems that are optimal in terms of query, time and space complexities. * We develop a generalisation of quantum walks that connects electrical properties of a graph and its quantum hitting time. We use it to construct a time-efficient quantum algorithm for 3-distinctness.Comment: PhD Thesis, 169 page

Development of a method to assess alignment of the foot and lower leg

ABSTRACT Ito S, Tomita Y, Tanabe S. Development of a method to assess alignment of the foot and lower leg. Jpn J Compr Rehabil Sci 2013; 4: 80-83. Purpose: Three-dimensional analyses of the foot and lower leg have been restricted to large-scale research facilities, since such analyses require a large experimental area and expensive measurement systems. Therefore, we developed a new threedimensional method of analyzing still pictures using commercially available digital cameras, and applied it to clinical use. Methods: We used three digital cameras. One was set 6 m behind the subject, while the other two were placed at 45 degrees to the right and left sides of the first camera, each the same distance from the subject. We used a plaster model of a lower leg and foot, on which several markers were mounted. The positions of the three-dimensional coordinates of the markers were computed by triangulation from the pictures taken with the three cameras, and the accuracy was verified. Results: The average reading error was 0.6 mm, and the average and maximum repetition errors were 1.3 mm and 1.6 mm, respectively. Comparison with direct evaluation was found to be 2.3% at maximum. These results showed that the method is highly reliable. Conclusion: Although a three-dimensional analysis using this method has the limitation of still picture analysis, it may be useful in many clinical applications because it requires only inexpensive apparatus and a small experimental area

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta