Asymmetries in core-collapse supernovae from maps of radioactive 44Ti in Cassiopeia A.

Asymmetry is required by most numerical simulations of stellar core-collapse explosions, but the form it takes differs significantly among models. The spatial distribution of radioactive (44)Ti, synthesized in an exploding star near the boundary between material falling back onto the collapsing core and that ejected into the surrounding medium, directly probes the explosion asymmetries. Cassiopeia A is a young, nearby, core-collapse remnant from which (44)Ti emission has previously been detected but not imaged. Asymmetries in the explosion have been indirectly inferred from a high ratio of observed (44)Ti emission to estimated (56)Ni emission, from optical light echoes, and from jet-like features seen in the X-ray and optical ejecta. Here we report spatial maps and spectral properties of the (44)Ti in Cassiopeia A. This may explain the unexpected lack of correlation between the (44)Ti and iron X-ray emission, the latter being visible only in shock-heated material. The observed spatial distribution rules out symmetric explosions even with a high level of convective mixing, as well as highly asymmetric bipolar explosions resulting from a fast-rotating progenitor. Instead, these observations provide strong evidence for the development of low-mode convective instabilities in core-collapse supernovae.

PROTEOMIC CHANGES OF RECOMBINANT YEAST: PHARMACO-INDUSTRIAL POTENTIAL.

The original yeast strain Hansenula anomala 2340 was implanted by low-energy nitrogen ion (N+) to obtain the mutant strain N6076. The mutant strain produced a red quinone compound, not synthesized by the parent strain. Two-dimensional fluorescence difference gel electrophoresis (2-D DIGE) and mass spectrometry (MS) were utilized to analyze the protein profile of the mutant strain N6076. The proteome changes were compared to those of the original strain to assess the amount of change that the metabolic pathways underwent in the mutant strain. The results indicated the detection of 57 different expressed proteins (P<0.05) when the N6076 mutant strain was cultured in the liquid medium for 96 h as compared to that of the original strain. Of these different expressed protein spots, 27 were upregulated, and 30 were down-regulated. Also, 56 protein spots were identified with the aid of MALDI-TOF and tandem (TOF-TOF) MS. The protein score confidence interval (CI) of the protein profiling in the down-regulated protein spots 273 and 1294 were 81.371% and 12.864%, respectively, by bioinformatic analysis. This probably points to the fact that the irradiation by N+ contributed to the mutation of these two proteins.

A mutant alpha-amylase with only part of the catalytic domain and its structural implication.

A truncated mutant alpha-amylase, Xa-S2, was obtained from Xanthomonas campestris wild type alpha-amylases (Xa-WT) through random mutagenesis that contained 167 amino acid residues (approx 65% shorter than that of Xa-WT). Secondary structure prediction implied that Xa-S2, would be unable to form the whole (beta/alpha)(8)-barrel catalytic domain and did not have the three conserved catalytic residues of wild type alpha-amylase, but it still displays the starch-hydrolyzing activity. Xa-S2 was prepared, characterized and compared to the recombinant wild-type enzymes. The K (m) for starch was 32 mg/ml; activity was optimal at pH 6.2 and 30 degrees C. In contrast, the K (m) for starch of Xa-WT was 8 mg/ml and optimal enzyme activity was at pH 6.0-6.2 and 45-50 degrees C. Our results suggested that Xa-S2 is a new amylase with a minimal catalytic domain for hydrolyzing substrates with of alpha-1,4-glucosidic bonds.

Supernovae. 44Ti gamma-ray emission lines from SN1987A reveal an asymmetric explosion.

In core-collapse supernovae, titanium-44 ((44)Ti) is produced in the innermost ejecta, in the layer of material directly on top of the newly formed compact object. As such, it provides a direct probe of the supernova engine. Observations of supernova 1987A (SN1987A) have resolved the 67.87- and 78.32-kilo-electron volt emission lines from decay of (44)Ti produced in the supernova explosion. These lines are narrow and redshifted with a Doppler velocity of ~700 kilometers per second, direct evidence of large-scale asymmetry in the explosion.

The oxygen isotopic composition of the Sun inferred from captured solar wind.

All planetary materials sampled thus far vary in their relative abundance of the major isotope of oxygen, (16)O, such that it has not been possible to define a primordial solar system composition. We measured the oxygen isotopic composition of solar wind captured and returned to Earth by NASA's Genesis mission. Our results demonstrate that the Sun is highly enriched in (16)O relative to the Earth, Moon, Mars, and bulk meteorites. Because the solar photosphere preserves the average isotopic composition of the solar system for elements heavier than lithium, we conclude that essentially all rocky materials in the inner solar system were enriched in (17)O and (18)O, relative to (16)O, by ~7%, probably via non-mass-dependent chemistry before accretion of the first planetesimals.

Description of Saccharomonospora xinjiangensis sp. nov. based on chemical and molecular classification.

Comparative studies of morphology, physiology, biochemistry and chemical composition of cells, and phylogenetic analysis based on 16S rRNA gene sequences were carried out with strains XJ-54T and XJ-58 of the genus Saccharomonospora and type strains of related genera. The results indicated that the two strains are different from known members of the genus Saccharomonospora. A new species with the name Saccharomonospora xinjiangensis sp. nov. is proposed. The new species is characterized by the presence of longitudinal pairs of spores on both the aerial and the vegetative hyphae and contains phosphatidyl ethanolamine, phosphatidyl choline and unknown glucosamine-containing phospholipids, and the major menaquinones MK-9(H2), MK-9(H4) and MK-7(H4).

Optimization of graded multilayer designs for astronomical X-ray telescopes.

We developed a systematic method for optimizing the design of depth-graded multilayers for astronomical hard-x-ray and soft-gamma-ray telescopes based on the instrument's bandpass and the field of view. We apply these methods to the design of the conical-approximation Wolter I optics employed by the balloon-borne High Energy Focusing Telescope, using W/Si as the multilayer materials. In addition, we present optimized performance calculations of mirrors, using other material pairs that are capable of extending performance to photon energies above the W K-absorption edge (69.5 keV), including Pt/C, Ni/C, Cu/Si, and Mo/Si.

Three new species of the genus Actinobispora of the family Pseudonocardiaceae, Actinobispora alaniniphila sp. nov., Actinobispora aurantiaca sp. nov. and Actinobispora xinjiangensis sp. nov.

The genus Actinobispora Jiang et al. is characterized by the formation of longitudinally paired spores on both the vegetative and the aerial mycelium, absence of mycolic acid, cell wall chemotype IV (containing meso-diaminopimelic acid as the diamino acid, galactose and arabinose), PVI and MK-9(H2). Comparative studies of morphology, chemical classification and phylogenetic analysis based on the 16S rRNA sequences among the four type strains of the genus Actinobispora and type strains of related genera were carried out. The results indicated that the genus Actinobispora is different from these other genera and should be placed in the family Pseudonocardiaceae Embley et al. 1988 with the genera Amycolatopsis, Pseudonocardia, Saccharomonospora, Saccharopolyspora and Actinopolyspora. On the bases of these results, three new species under the names of Actinobispora alaniniphila sp. nov., Actinobispora aurantiaca sp. nov. and Actinobispora xinjiangensis sp. nov. are proposed; the type strains are CCTCC AA97001T, CCTCC AA97002T and CCTCC AA97020T.

Streptimonospora salina gen. nov., sp. nov., a new member of the family Nocardiopsaceae.

Actinomycete strain YIM 90002T (= CCTCC 99003T = CCRC 16284T) was isolated from a soil sample collected from a salt lake in the west of China. The aerial mycelium of this organism is well developed but not fragmented and, at maturity, forms short chains of spores. Spores in short chains are oval- to rod-shaped and have wrinkled surfaces. Substrate mycelium is branched with non-fragmenting hyphae and forms single oval to round spores borne on sporophores or dichotomously branching sporophores. Single spores have wrinkled surfaces. Single spores and spores in short chains are non-motile. Strain YIM 90002T contains meso-diaminopimelic acid, DD-diaminopimelic acid, glycine, lysine and aspartic acid in its cell wall and has glucose, galactose, ribose, xylose, arabinose and mannose as whole-cell sugars (no diagnostic sugars). The phospholipids are phosphatidylglycerol, phosphatidylinositol and phosphatidylethanolamine. The major menaquinones are MK-9(H6), MK-10(H2) and MK-10(H4). Phylogenetic data indicate that this strain belongs to the family Nocardiopsaceae. The morphological and physiological characteristics and chemotaxonomic and phylogenetic data for this strain differ from those of previously described actinomycetes. Therefore, a new genus, Streptimonospora, is proposed for this organism; the type species of the genus is Streptimonospora salina gen. nov., sp. nov., and the type strain of S. salina is strain YIM 90002T.