Differential Rotation and Dynamics of the Solar Interior

Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within the solar interior. The nearly uninterrupted observations by the Global Oscillation Network Group (GONG) yield oscillation power spectra with high duty cycles and high signal-to-noise ratios. Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths. A distinctive shear layer just below the surface is discernible at low to mid-latitudes.     

Association between groat protein percentage and certain plant and seed traits in interspecific oat crosses

Summary Ten interspecific crosses of Avena sativa L. x A. sterilis L. were used to study associations of groat protein percentage with selected seed and agronomic traits. Each cross was grown in a replicated experiment, and the genetic material consisted of parents and F₂-derived lines grown in the F₄ generation.No close associations were found between groat protein percentage and plant height, heading date, or 10-groat weight. Individual crosses did show significant correlations, but none of the 3 traits was sufficiently associated with groat protein generally so as to be beneficial or inhibitory to combining high groat-protein percentage with the maturity, plant height, and 10-groat weight appropriate for good agronomic cultivars of oats.High groat-protein percentage was closely associated with abscission spikelet separation and jointed awn, both of which are A. sterilis traits. Shattering and dark seed color (A. sterilis traits) were also associated with high groat protein percentage, but kernel pubescence was not. Only a few segregates within each cross were A. sativa type for all 5 of the seed traits, but when A. sativa types from all crosses were grouped together, there was a large range for groat-protein percentages.Journal Paper No J-6950 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project 1752. In cooperation with the Crops Research Division, Agricultural Research Service, U.S. Department of Agriculture. Carried out with a grant from the Quaker Oat Co., Chicago, Illinois, USA.     

Inheritance of straw-protein content and its association with other traits in interspecific oat crosses

Summary Ten interspecific crosses of Avena sativa L. x A. sterilis L. were used to study inheritance of protein content in oat straw and its associations with selected seed and agronomic traits. Each cross was grown in a replicated experiment, and the materials for each cross consisted of parents and F₂-derived lines in the F₄ generation. Straw-protein percentages were transformed to square roots to normalize the data before statistical analyses were carried out.Frequency distributions were reasonably symmetrical for square roots of straw-protein percentages (SP%) in eight crosses, suggesting that additive gene action conditioned this trait. There was a preponderance of low SP% lines in the remaining two crosses. SP% was not consistently correlated with plant height, 10-groat weight, or groat-protein percentage. SP% was positively and significantly correlated with heading date in all crosses, so the SP% variances were adjusted for heading date by covariance analyses. Whereas all crosses had significant variability among F₂-derived lines for SP% before covariance analysis, only two showed significant variability after adjustment for heading date.Mean per-plot and per-experiment heritabilities for SP% before adjustment for heading date were 56 and 69%, respectively, whereas after adjustment for heading date, they were 22 and 32%, respectively. Although the inheritance of SP% appears relatively simple, this trait is greatly influenced by date of maturity.Journal paper No J-7603 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, USA. Project 1752 Supported in part by a grant from the Quaker Oats Co., Chicago, Ill., USA.     

Evaluation of cold hardiness in two sets of near-isogenic lines of wheat (Triticum aestivum) with polymorphic vernalization alleles

In wheat, variation at the orthologus Vrn‐1 loci, located on each of the three genomes, A, B and D, is responsible for vernalization response. A dominant Vrn‐1a allele on any of the three wheat genomes results in spring habit and the presence of recessive Vrn‐1b alleles on all three genomes results in winter habit. Two sets of near‐isogenic lines (NILs) were evaluated for DNA polymorphisms at their Vrn‐A1, B1 and D1 loci and for cold hardiness. Two winter wheat cultivars, ‘Daws’ and ‘Wanser’ were used as recurrent parents and ‘Triple Dirk’ NILs were used as donor parents for orthologous Vrn‐1 alleles. The NILs were analysed using molecular markers specific for each allele. Only 26 of 32 ‘Daws’ NILs and 23 of 32 ‘Wanser’ NILs had a plant growth habit that corresponded to the marker genotype for the markers used. Freezing tests were conducted in growth chambers programmed to cool to ?21.5°C. Relative area under the death progress curve (AUDPC), with a maximum value of 100 was used as a measure of death due to freezing. The average relative AUDPC of the spring habit ‘Daws’Vrn‐A1a NILs was 86.15; significantly greater than the corresponding winter habit ‘Daws’Vrn‐A1b NILs (42.98). In contrast, all the ‘Daws’Vrn‐A1bVrn‐B1aVrn‐D1b and Vrn‐A1bVrn‐B1bVrn‐D1a NILs (spring habit) had relative AUDPC values equal to those of their ‘Daws’ sister genotypes with Vrn‐A1bVrn‐B1bVrn‐D1b NILs (winter habit). The average AUDPC of spring and winter habit ‘Wanser’ NILs differed at all three Vrn‐A1, Vrn‐B1 and Vrn‐D1 locus comparisons. We conclude that ‘Daws’ and ‘Wanser’ have different background genetic interactions with the Vrn‐1 loci influencing cold hardiness. The marker for Vrn‐A1 is diagnostic for growth habit and cold hardiness but there is no relationship between the Vrn‐B1 and Vrn‐D1 markers and the cold tolerance of the NILs used in this study.     

Demonstration of X-ray Holography with an X-ray Laser

An x-ray hologram was made by means of an x-ray laser and a laser-quality near normal incidence x-ray mirror. The high brightness and large coherence lengths of x-ray lasers now offer the potential for in vitro three-dimensional high-resolution holographic images of dynamically varying biological microstructures.     

Mars north polar deposits: stratigraphy, age, and geodynamical response

The Shallow Radar (SHARAD) on the Mars Reconnaissance Orbiter has imaged the internal stratigraphy of the north polar layered deposits of Mars. Radar reflections within the deposits reveal a laterally continuous deposition of layers, which typically consist of four packets of finely spaced reflectors separated by homogeneous interpacket regions of nearly pure ice. The packet/interpacket structure can be explained by approximately million-year periodicities in Mars' obliquity or orbital eccentricity. The observed approximately 100-meter maximum deflection of the underlying substrate in response to the ice load implies that the present-day thickness of an equilibrium elastic lithosphere is greater than 300 kilometers. Alternatively, the response to the load may be in a transient state controlled by mantle viscosity. Both scenarios probably require that Mars has a subchondritic abundance of heat-producing elements.     

Deep Impact: observations from a worldwide Earth-based campaign

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics.     

Nicotine is chemotactic for neutrophils and enhances neutrophil responsiveness to chemotactic peptides

Neutrophils contribute to chronic bronchitis and pulmonary emphysema associated with cigarette smoking. Nicotine was found to be chemotactic for human neutrophils but not monocytes, with a peak activity at approximately 31 micromolar. In lower concentrations (comparable to those in smokers' plasma), nicotine enhanced the response of neutrophils to two chemotactic peptides. In contrast to most other chemoattractants for neutrophils, however, nicotine did not affect degranulation or superoxide production. Nicotine thus may promote inflammation and consequent lung injury in smokers.