ALBERT

Description: Background: Propionibacteria are part of the human microbiota. Many studies have addressed the predominant colonizer of sebaceous follicles of the skin, Propionibacterium acnes, and investigated its association with the skin disorder acne vulgaris, and lately with prostate cancer. Much less is known about two other propionibacterial species frequently found on human tissue sites, Propionibacterium granulosum and Propionibacterium avidum. Here we analyzed two and three genomes of P. granulosum and P. avidum, respectively, and compared them to two genomes of P. acnes; we further highlight differences among the three cutaneous species with proteomic and microscopy approaches. Results: Electron and atomic force microscopy revealed an exopolysaccharide (EPS)-like structure surrounding P. avidum cells, that is absent in P. acnes and P. granulosum. In contrast, P. granulosum possesses pili-like appendices, which was confirmed by surface proteome analysis. The corresponding genes were identified; they are clustered with genes encoding sortases. Both, P. granulosum and P. avidum lack surface or secreted proteins for predicted host-interacting factors of P. acnes, including several CAMP factors, sialidases, dermatan-sulphate adhesins, hyaluronidase and a SH3 domain-containing lipoprotein; accordingly, only P. acnes exhibits neuraminidase and hyaluronidase activities. These functions are encoded on previously unrecognized island-like regions in the genome of P. acnes. Conclusions: Despite their omnipresence on human skin little is known about the role of cutaneous propionibacteria. All three species are associated with a variety of diseases, including postoperative and device-related abscesses and infections. We showed that the three organisms have evolved distinct features to interact with their human host. Whereas P. avidum and P. granulosum produce an EPS-like surface structure and pili-like appendices, respectively, P. acnes possesses a number of unique surface-exposed proteins with host-interacting properties. The different surface properties of the three cutaneous propionibacteria are likely to determine their colonizing ability and pathogenic potential on the skin and at non-skin sites.

Description: We present a new technique for the statistical evaluation of the Tully–Fisher relation (TFR) using spectral line stacking. This technique has the potential to extend TFR observations to lower masses and higher redshifts than possible through a galaxy-by-galaxy analysis. It further avoids the need for individual galaxy inclination measurements. To quantify the properties of stacked H i emission lines, we consider a simplistic model of galactic discs with analytically expressible line profiles. Using this model, we compare the widths of stacked profiles with those of individual galaxies. We then follow the same procedure using more realistic mock galaxies drawn from the S 3 -SAX model (a derivative of the Millennium simulation). Remarkably, when stacking the apparent H i lines of galaxies with similar absolute magnitude and random inclinations, the width of the stack is very similar to the width of the deprojected (= corrected for inclination) and dedispersed (= after removal of velocity dispersion) input lines. Therefore, the ratio between the widths of the stack and the deprojected/dedispersed input lines is approximately constant – about 0.93 – with very little dependence on the gas dispersion, galaxy mass, galaxy morphology and shape of the rotation curve. Finally, we apply our technique to construct a stacked TFR using H i Parkes All-Sky Survey (HIPASS) data which already has a well-defined TFR based on individual detections. We obtain a B -band TFR with a slope of –8.5 ± 0.4 and a K -band relation with a slope of –11.7 ± 0.6 for the HIPASS data set which is consistent with the existing results.

Description: We report sputtering measurements of anorthite-like material, taken to be representative of soils found in the lunar highlands, impacted by singly and multicharged ions representative of the solar wind. The ions investigated include protons, as well as singly and multicharged Ar ions (as proxies for the non-reactive heavy solar wind constituents), in the charge state range +1 to +9, at fixed solar-wind-relevant impact velocities of 165 and 310 km/s (0.25 keV/amu and 0.5 keV/amu). A quartz microbalance approach (QCM) for determination of total sputtering yields was used. The goal of the measurements was to determine the sputtering contribution of the heavy, multicharged minority solar wind constituents in comparison to that due to the dominant H + fraction. The QCM results show a yield increase of a factor of about 80 for Ar + vs H + sputtering and an enhancement by a factor of 1.67 between Ar 9+ and Ar + , which is a clear indication of a potential sputtering effect.

Description: Comproportionation reactions of rare-earth metal trihalides, RX 3 , with the respective R metal in the presence of a transition metal Z , preferably from group 8 through 10, yielded single crystals of 31 { ZR 6 } X 12 R and 22 { ZR 6 } X 10 type compounds, in most cases for the first time, especially with R = Tb, Dy, Ho, and Er. These are compared with literature entries. The crystal structures are discussed for the equal-atom pair {IrEr 6 }I 12 Er and {IrEr 6 }I 10 . In both cases, {IrEr 6 }I i 12 I a 6 cluster complexes are connected via i-i and i-a/a-i bridges, respectively, the {IrEr 6 } clusters are isolated. Band structure calculations were carried out on the LMTO-ASA level for a number of { Z Y 6 } X 10 examples; the density of states (DOS) and Crystal Orbital Hamiltonian Populations (COHP) derived therefrom exhibit strong Z– Y and Y –X bonding interactions. Most profitable are X = I and endohedral elements of sixth period atoms, especially Z = Os, Ir.

Description: Trehalose represents the main hemolymph sugar in most insects and its metabolic availability is regulated by trehalase. In this study, trehalase activity associated with the reproductive system was investigated in the insect Rhodnius prolixus, a hematophagous hemipteran vector of Chagas’ disease. A single-copy gene that encodes a membrane-bound trehalase (RpTre-2) was identified in the genome of R. prolixus. RpTre-2 deduced amino acid sequence is closely related to other insect membrane-bound trehalases. The expression of this gene was detected in all analyzed organs, including ovary, where total trehalase enzymatic activity was determined, and was highest at day 7 after blood meal. Ovary membranes showed a major trehalase specific activity, which confirmed the presence of a membrane-bound trehalase in this insect. This trehalase activity seemed not to be regulated at transcriptional level, as the expression of RpTre-2 gene in the ovary did not change over the days after feeding. Similarly, ovarian follicles at different developmental stages did not show any variation in the transcription level of this gene. The RpTre-2 kinetic parameters were also investigated. Activity was highest at pH 5.5 and followed Michaelis–Menten kinetics, with an apparent K m = 1.42 ± 0.36 mM and Vmax = 167.90 ± 12.91 nmol/mg protein/h. These data reveal the presence of a membrane-bound trehalase in R. prolixus that is active in ovary and probably takes part in the insect carbohydrate metabolism associated with the reproductive process.

Description: In this paper, we present measurements of He + and He +2 ion-induced sputtering of an anorthite-like thin film at a fixed solar-wind-relevant impact energy of ~0.5 keV/amu using a quartz crystal microbalance approach (QCM) for determination of total absolute sputtering yields. He +2 ions are the most abundant multicharged ions in the solar wind and increased sputtering by these ions in comparison to equi-velocity He + ions is expected to have the biggest effect on the overall sputtering efficiency of solar wind impact on the moon. Our measurements indicate an almost doubling of the sputtering yield for doubly charged incident He ions compared to same velocity He + impact. Using a selective sputtering model, the new QCM results presented here, together with previously published results for Ar +q ions and SRIM results for the relevant kinetic sputtering yields, the effect due to multicharged solar-wind ion impact on local near-surface modification of lunar anorthite-like soil is explored. It is shown that the multicharged solar wind component leads to a more pronounced and significant differentiation of depleted and enriched surface elements as well as a shortening of the timescale over which such surface compositional modifications might occur in astrophysical settings. In addition, to validate previous and future determinations of multicharged-ion-induced sputtering enhancement for those cases where the QCM approach can’t be used, relative quadrupole-mass-spectrometry (QMS) based measurements are presented for the same anorthite-like thin film as were investigated by QCM, and their suitability and limitations for charge-state-enhanced yield measurements are discussed.