N. Kimura

The filamentous fungus Alternaria alternata produces melanin, a black pigment, from acetate via 1,8-dihydroxynaphthalene. To isolate a fungal gene required for melanin biosynthesis, we transformed an A. alternata Brm1- (light brown) mutant with the DNA of a wild-type strain genomic library constructed by use of a cosmid carrying the hygromycin B phosphotransferase gene. When hygromycin B-resistant transformants were screened for melanin production, 1 of 1,363 transformants appeared to regain melanin production, as judged by black pigmentation of the cultured mycelia. The cosmid, named pMBR1, was recovered by packaging nuclear DNA of the melanin-producing transformant into lambda phage. The gene on pMBR1 that enables the Brm1- mutant to produce melanin was designated BRM1. In addition to the BRM1 gene, pMBR1 was found to carry two more genes involved in melanin biosynthesis. These two genes, designated ALM and BRM2, transformed A. alternata Alm- (albino) and Brm2- (brown) mutants, respectively, to the wild-type phenotype. The three genes are located within a ca. 30-kb genomic region in the order ALM-BRM1-BRM2. Analysis of the gene transcripts indicated approximate sizes of 7.2, 4.0, and 0.9 kb for ALM, BRM1, and BRM2, respectively. The BRM1 and BRM2 transcripts are generated from the same strand, but the ALM transcript is generated from the opposite strand. The three mRNA species accumulate in cultured mycelia of the wild-type strain synchronously with mycelial melanization. The essential roles of the three genes in melanin biosynthesis were confirmed by transformation-mediated gene disruption experiments.

The Improved Limb Atmospheric Spectrometer‐II (ILAS‐II) monitored components associated with Polar ozone depletion. ILAS‐II was on board the Advanced Earth Observing Satellite‐II (ADEOS‐II, “Midori‐II”), which was successfully launched on 14 December 2002 from the Tanegashima Space Center of the Japan Aerospace Exploration Agency (JAXA). ILAS‐II used a solar occultation technique to measure vertical profiles of ozone (O 3 ), nitric acid (HNO 3 ), nitrogen dioxide (NO 2 ), nitrous oxide (N 2 O), methane (CH 4 ), water vapor (H 2 O), chlorine nitrate (ClONO 2 ), dinitrogen pentoxide (N 2 O 5 ), CFC‐11, CFC‐12 and aerosol extinction coefficients at high latitudes in both the Northern and Southern hemispheres. ILAS‐II included Sun‐tracking optics and four spectrometers, a Sun‐edge sensor, and electronics. The four spectrometers measured in the infrared (channel 1) between 6.21 and 11.76 μm, in the midinfrared (channel 2) between 3.0 and 5.7 μm, at high resolution in the infrared (channel 3) between 12.78 and 12.85 μm, and in the visible (channel 4) between 753 and 784 nm. The vertical height of the entrance slit was 1 km at the tangent point. A Sun‐edge sensor accurately registered tangent height. After an initial check of the instruments, ILAS‐II recorded routine measurements for about 7 months, from 2 April 2003 to 24 October 2003, a period that included the formation and collapse of an Antarctic ozone hole in 2003 that was one of the largest in history. All of the ILAS‐II data were processed using the version 1.4 data‐processing algorithm. Validation analyses show promising results for some ILAS‐II measurement species, which can be used to elucidate mechanisms of Polar ozone depletion. Studies are ongoing on ozone depletion, on the formation mechanisms of Polar stratospheric clouds, on denitrification, and on air mass descent. A state‐of‐the‐art data retrieval algorithm that is currently being developed will yield more sophisticated data sets from the ILAS‐II data in the near future.

BACKGROUND: One of the features of Helicobacter pylori infection in the human stomach seems to be disordered gastric acid secretion. The effect of vacuolating toxin (VT) produced by H. pylori on gastric acid secretion was examined. METHODS: VT(+)(toxigenic) and VT(-)(nontoxigenic) strains of H. pylori were cultured in brucella broth. The culture supernatant was added to isolated parietal cells, and acid secretion and intracellular adenosine 3'5'-cyclic phosphate (cAMP) and Ca2+ levels were measured with the 14C-aminopyrine (14C-AP) method, with 125I radioimmunoassay (RIA), and with the fura-2 fluorescence method, respectively. RESULTS: In the VT(+) strain a considerable inhibitory effect on 14C-AP accumulation was observed. However, the VT(-) strain had no significant effect on intracellular c-AMP and Ca2+. CONCLUSIONS: The VT(+) strain of H. pylori has an inhibitory effect on gastric acid secretion, whereas the VT(-) strain does not. This inhibitory effect was not associated with the response of second messengers. It is speculated that VT produced by H. pylori has a direct action on H(+)-K+ adenosine triphosphatase in parietal cells.

The Improved Limb Atmospheric Spectrometer (ILAS) was a satellite‐based solar occultation sensor that was developed by the Environment Agency of Japan (EA) to monitor and study the stratospheric ozone layer. This paper describes the characteristics of the ILAS instrument and its performance in orbit. ILAS measured the vertical distribution of ozone, nitric acid, nitrogen dioxide, nitrous oxide, methane, water vapor, temperature, pressure, and aerosol extinction coefficients at 1.6‐km vertical resolution. ILAS was equipped with two spectrometers: an infrared (IR) spectrometer with an uncooled pyroelectric linear array detector to sense between 6.21 and 11.76 μm and a visible spectrometer to monitor 753–784 nm. In addition, a Sun‐edge sensor (SES) assigned the tangent height of the instantaneous field‐of‐view (IFOV). A two‐axis gimbals control system on ILAS used two Sun position sensors to track the center of brightness of the Sun during occultation measurements. Before launch onboard the Advanced Earth Observing Satellite (ADEOS), the performance of ILAS was checked on the ground using several methods, including gas‐cell measurements, time response measurements, Sun‐tracking tests, and hollow‐cathode lamp measurements. After the launch of ADEOS on 17 August 1996, ILAS functioned successfully for 8 months of routine operation, from 30 October 1996 to 30 June 1997, collecting more than 6700 solar occultation measurements, after which time the satellite failed due to a failure in a solar paddle. The time delay response of the IR channel was characterized using stepwise IR input. Instrument functions of the ILAS IR and visible spectrometers were determined by combining theoretical optical calculations, experimental measurements using a gas‐cell before launch, and in‐orbit data. The signal‐to‐noise ratio (SNR) of each element in the IR channel was estimated to be 400–1200. In the visible channel, it was 1600–1800 for a 100% direct Sun signal. At sunset occultation, ILAS was able to track the Sun below a tangent height of 10 km in some cases. The method of determining the solar edges from the SES data worked correctly, giving adequate tangent height information for observations. Output signal levels of the SES, visible channel, and IR channel showed slight degradation during the period that ILAS was operational, which is attributed to space‐borne contaminants. However, changes in absolute signal levels do not affect data retrieval, because the solar occultation technique was self‐calibrating. Overall, ILAS worked as designed during its operation in orbit and gathered valuable data for ozone layer studies.

An injector of an electron linear accelerator has been modified at ISIR of Osaka University in order to increase a single bunch charge from 14 nC to 60 nC. A 6th subharmonic prebuncher has been replaced with two 12th subharmonic prebunchers and a 6th subharmonic prebuncher which are newly constructed. A one-dimensional disk model has been used to calculate the bunching of the beam and to decide the optimum location of the subharmonic prebunchers. The subharmonic prebunchers are immersed in a solenoidal magnetic field so that the electron beam is confined during the travel through the drift region. The single bunch of 16 - 20 ps duration and up to 67 nC in charge, with the energy spread of 0.7 - 2.5 % over the range of 24 - 34 MeV, and a repetition rate from a single shot to 720 pps can be obtained. The energy spread depends on the charge and the minimum spread is 0.7 % at 33 nC. The single bunch of 25 - 45 nC in charge is used for the experiments in routine work.