Cordycepin in Schizosaccharomyces pombe: effects on the wild type and phenotypes of mutants resistant to the drug

The adenosine analogue cordycepin (3′-deoxyadenosine) inhibits growth and causes aberrant cell morphology in the fission yeast, Schizosaccharomyces pombe. Exogenously added thiamine, the pyrimidine moiety of the thiamine molecule, and adenine alleviate its growth-disturbing effect. At concentrations that do not inhibit growth, the drug reduces mating and sporulation and causes a decrease in the mRNA level of gene ste11 and the ste11-dependent gene, mei2. The mating- and sporulation-inhibiting effect of cordycepin is overcome by adenine. A mutant disrupted for the ado1 gene encoding adenosine kinase exhibits a cordycepin-resistant and methionine-sensitive phenotype, excretes adenosine into the medium and mates and sporulates poorly in the presence of adenine. A S. pombe mutant containing a frameshift mutation at the beginning of the carboxy-terminal half of gene ufd1 (the Saccharomyces cerevisiae UFD1 homologue) is cordycepin-resistant and sterile. Strains disrupted for the ufd1 gene only form microcolonie

Computer experiments to determine whether over- or under-counting necessarily affects the determination of difference in cell number between experimental groups

Cataloged from PDF version of article.Computer cell counting experiments were performed in order to examine the consequences of over- or under-counting. The three-dimensional reaggregate culture laboratory environment for cell counting was used as a model for computer simulation. The laboratory environment for aggregate and cell sizes, numbers and spatial placement in gelatin blocks was mimicked in the computer setup. However, in the computer, cell counting was set to be either ideally unbiased, or deliberately biased in regard to over- or under-counting so as to compare eventual results when using the various cell counting methods. It was found that there was no effect of the cell counting methods used in determining whether there was a significant difference in cell number between two experimental groups. In addition, it was found that under the conditions of these simulations, the optical disector method behaved similarly, on the average, as the ideal method of counting cell centers and in both of those cases, the average ratio between actual cell number in a flask and estimated number was close to 1.00. © 2001 Elsevier Science B.V. All rights reserved

Applications of Abundance Data and Requirements for Cosmochemical Modeling

Understanding the evolution of the universe from Big Bang to its present state requires an understanding of the evolution of the abundances of the elements and isotopes in galaxies, stars, the interstellar medium, the Sun and the heliosphere, planets and meteorites. Processes that change the state of the universe include Big Bang nucleosynthesis, star formation and stellar nucleosynthesis, galactic chemical evolution, propagation of cosmic rays, spallation, ionization and particle transport of interstellar material, formation of the solar system, solar wind emission and its fractionation (FIP/FIT effect), mixing processes in stellar interiors, condensation of material and subsequent geochemical fractionation. Here, we attempt to compile some major issues in cosmochemistry that can be addressed with a better knowledge of the respective element or isotope abundances. Present and future missions such as Genesis, Stardust, Interstellar Pathfinder, and Interstellar Probe, improvements of remote sensing instrumentation and experiments on extraterrestrial material such as meteorites, presolar grains, and lunar or returned planetary or cometary samples will result in an improved database of elemental and isotopic abundances. This includes the primordial abundances of D, ^3He, ^4He, and ^7Li, abundances of the heavier elements in stars and galaxies, the composition of the interstellar medium, solar wind and comets as well as the (highly) volatile elements in the solar system such as helium, nitrogen, oxygen or xenon

STEREO/SEPT observations of upstream particle events: almost monoenergetic ion beams

We present observations of Almost Monoenergetic Ion (AMI) events in the energy range of 100–1200 keV detected with the Solar Electron and Proton Telescope (SEPT) onboard both STEREO spacecraft. The energy spectrum of AMI events contain 1, 2, or 3 narrow peaks with the relative width at half maximum of 0.1–0.7 and their energy maxima varies for different events from 120 to 1200 keV. These events were detected close to the bow-shock (STEREO-A&B) and to the magnetopause at STEREO-B as well as unexpectedly far upstream of the bow-shock and far away from the magnetotail at distances up to 1100 <I>R<sub>E</sub></I> (STEREO-B) and 1900 <I>R<sub>E</sub></I> (STEREO-A). We discuss the origin of AMI events, the connection to the Earth's bow-shock and to the magnetosphere, and the conditions of the interplanetary medium and magnetosphere under which these AMI bursts occur. Evidence that the detected spectral peaks were caused by quasi-monoenergetic beams of protons, helium, and heavier ions are given. Furthermore, we present the spatial distribution of all AMI events from December 2006 until August 2007

Unusual composition of the solar wind in the 2–3 May 1998 CME observed with SWICS on ACE

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95193/1/grl11810.pd

Gender Differences in Interest and Knowledge Acquisition: The United States, Taiwan, and Japan

The relationship between interest and knowledge was investigated in a representative sample of 11th grade students from cultures that differ in the strength of their gender-role stereotypes and their endorsement of effort-based versus interest-based learning. Among 11th graders from the United States ( N = 1052), Taiwan ( N = 1475), and Japan ( N = 1119), boys preferred science, math, and sports, whereas girls preferred language arts, music, and art. General information scores were comparable across the three locations; however, boys consistently outscored girls. Gender and interest in science independently predicted general information scores, whereas gender and interest in math independently predicted mathematics scores. Cultural variations in the strength of the relationship between gender, interest, and scores indicate that specific socialization practices can minimize or exaggerate these gender differences.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45629/1/11199_2004_Article_454958.pd

Nanodust detection near 1 AU from spectral analysis of Cassini/RPWS radio data

Nanodust grains of a few nanometer in size are produced near the Sun by collisional break-up of larger grains and picked-up by the magnetized solar wind. They have so far been detected at 1 AU by only the two STEREO spacecraft. Here we analyze the spectra measured by the radio and plasma wave instrument onboard Cassini during the cruise phase close to Earth orbit; they exhibit bursty signatures similar to those observed by the same instrument in association to nanodust stream impacts on Cassini near Jupiter. The observed wave level and spectral shape reveal impacts of nanoparticles at about 300 km/s, with an average flux compatible with that observed by the radio and plasma wave instrument onboard STEREO and with the interplanetary flux models

On the bulk isotopic composition of magnesium and silicon during the May 1998 CME: ACE/SWIMS

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95217/1/grl11855.pd