Modulation of the asymmetry of sea urchin sperm flagellar bending by calmodulin

Sea urchin spermatozoa demembranated with Triton X-100 in the presence of EGTA, termed potentially asymmetric, generate asymmetric bending waves in reactivation solutions containing EGTA. After they are converted to the potentially symmetric condition by extraction with Triton and millimolar Ca++, they generate symmetric bending waves in reactivation solutions containing EGTA. In the presence of EGTA, their asymmetry can be restored by addition of brain calmodulin or the concentrated supernatant obtained from extraction with Triton and millimolar Ca++. These extracts contain calmodulin, as assayed by gel electrophoresis, radioimmunoassay, activation of brain phosphodiesterase, and Ca++-dependent binding of asymmetry-restoring activity to a trifluorophenothiazine-affinity resin. Conversion to the potentially symmetric condition can also be achieved with trifluoperazine substituted for Triton during the exposure to millimolar Ca++, which suggests that the calmodulin-binding activity of Triton is important for this conversion. These observations suggest that the conversion to the potentially symmetric condition is the result of removal of some of the axonemal calmodulin and provide additional evidence for axonemal calmodulin as a mediator of the effect of Ca++ on the asymmetry of flagellar bending

Near-Solar-Circle Method for Determination of the Galactic Constants

We propose a method to determine the galactic constants R_0 (distance to the Galactic Center) and V_0 (rotation velocity of the Sun) from measurements of distances, radial velocities and proper motions of objects near the solar circle. This is a modification of the solar-circle method to a more practical observational method. We apply the method to determine R_0 using data from the literature with known distances and radial velocities, and obtain R_0 = 7.54 +/- 0.77 kpc.Comment: 5 pages, 4 figures, accepted for PASJ (Vol. 63 No. 5

Two fast X-ray transients in archival Chandra data

We present the discovery of two new X-ray transients in archival Chandra data. The first transient, XRT 110103, occurred in January 2011 and shows a sharp rise of at least three orders of magnitude in count rate in less than 10 s, a flat peak for about 20 s and decays by two orders of magnitude in the next 60 s. We find no optical or infrared counterpart to this event in preexisting survey data or in an observation taken by the SIRIUS instrument at the Infrared Survey Facility 2.1 yr after the transient, providing limiting magnitudes of J>18.1, H>17.6 and Ks>16.3. This event shows similarities to the transient previously reported in Jonker et al. which was interpreted as the possible tidal disruption of a white dwarf by an intermediate mass black hole. We discuss the possibility that these transients originate from the same type of event. If we assume these events are related a rough estimate of the rates gives 1.4*10^5 per year over the whole sky with a peak 0.3-7 keV X-ray flux greater than 2*10^-10 erg cm^-2 s^-1 . The second transient, XRT 120830, occurred in August 2012 and shows a rise of at least three orders of magnitude in count rate and a subsequent decay of around one order of magnitude all within 10 s, followed by a slower quasi-exponential decay over the remaining 30 ks of the observation. We detect a likely infrared counterpart with magnitudes J=16.70+/-0.06, H=15.92+/-0.04 and Ks=15.37+/-0.06 which shows an average proper motion of 74+/-19 milliarcsec per year compared to archival 2MASS observations. The JHKs magnitudes, proper motion and X-ray flux of XRT 120830 are consistent with a bright flare from a nearby late M or early L dwarf.Comment: Accepted for publication in MNRAS, 6 pages, 5 figure

The KCAL VERA 22 GHz calibrator survey

We observed at 22 GHz with the VLBI array VERA a sample of 1536 sources with correlated flux densities brighter than 200 mJy at 8 GHz. One half of target sources has been detected. The detection limit was around 200 mJy. We derived the correlated flux densities of 877 detected sources in three ranges of projected baseline lengths. The objective of these observations was to determine the suitability of given sources as phase calibrators for dual-beam and phase-referencing observations at high frequencies. Preliminary results indicate that the number of compact extragalactic sources at 22 GHz brighter than a given correlated flux density level is twice less than at 8 GHz.Comment: Accepted for publication by the Astronomical Journal. 6 pages, 3 figures, 3 table. The machine readable catalogue file, kcal_cat.txt can be extracted from the source of this submissio

Optical to Near-IR Spectrum of a Massive Evolved Galaxy at z = 1.26

We present the optical to near-infrared (IR) spectrum of the galaxy TSPS J1329-0957, a red and bright member of the class of extremely red objects (EROs) at z = 1.26. This galaxy was found in the course of the Tokyo-Stromlo Photometry Survey (TSPS) which we are conducting in the southern sky. The spectroscopic observations were carried out with the Gemini Multi-Object Spectrograph (GMOS) and the Gemini Near Infra-Red Spectrograph (GNIRS) mounted on the Gemini-South telescope. The wide wavelength coverage of 0.6 - 2.3 um provides useful clues as to the nature of EROs while most published spectra are limited to a narrower spectral range which is dictated by the need for efficient redshift determination in a large survey. We compare our spectrum with several optical composite spectra obtained in recent large surveys, and with stellar population synthesis models. The effectiveness of using near-IR broad-band data, instead of the spectral data, in deriving the galaxy properties are also investigated. We find that TSPS J1329-0957 formed when the universe was 2 - 3 Gyr old, and subsequently evolved passively to become one of the most massive galaxies found in the z = 1 - 2 universe. Its early type and estimated stellar mass of M* = 10^{11.5} Msun clearly point to this galaxy being a direct ancestor of the brightest elliptical and spheroidal galaxies in the local universe.Comment: 18 pages, 4 figures. Accepted for publication in Ap