Influence of Amino Acid Substitutions in the Nisin Leader Peptide on Biosynthesis and Secretion of Nisin by Lactococcus lactis

Structural genes for small lanthionine-containing antimicrobial peptides, known as lantibiotics, encode N-terminal leader sequences which are not present in the mature peptide, but are cleaved off at some stage in the maturation process. Leader sequences of the different lantibiotics share a number of identical amino acid residues, but they are clearly different from sec-dependent protein export signal sequences. We studied the role of the leader sequence of the lantibiotic nisin, which is produced and secreted by Lactococcus lactis, by creating site-directed mutations at various positions in the leader peptide sequence. Mutations at Arg-1 and Ala-4, but not at the conserved Pro-2, strongly affected the processing of the leader sequence and resulted in the extracellular accumulation of a biologically inactive precursor peptide. Amino acid analysis and 1H NMR studies indicated that the precursor peptide with an Ala-4 → Asp mutation contained a modified nisin structural part with the (mutated) unmodified leader sequence still attached to it. The Ala-4 → Asp precursor peptide could be activated in vitro by enzymatic cleavage with trypsin, liberating nisin. These results confirmed that cleavage of the leader peptide is the last step in nisin maturation and is necessary to generate a biologically active peptide. Several mutations, i.e. Pro-2 → Gly, Pro-2 → Val, Asp-7 → Ala, Lys-9 → Leu, Ser-10 → Ala/Ser-12 → Ala and Val-11 → Asp/Val-13 → Glu in the leader peptide did not have any detectable effect on nisin production and secretion, although some of them affected highly conserved residues. When mutations were created in the -18 to -15 region of the nisin leader peptide (i.e. Phe-18 → Leu, Leu-16 → Lys, Asp-15 → Ala), no secretion or intracellular accumulation could be detected of nisin or its precursors. This suggested that these conserved residues are involved in the maturation process and may interact with lantibiotic-specific modifying enzymes.

Singular-boundary reductions of type-Q ABS equations

We study the fully discrete elliptic integrable model Q4 and its immediate trigonometric and rational counterparts (Q3, Q2 and Q1). Singular boundary problems for these equations are systematised in the framework of global singularity analysis. We introduce a technique to obtain solutions of such problems, in particular constructing the exact solution on a regular singularity-bounded strip. The solution technique is based on the multidimensional consistency and uses new insights into these equations related to the singularity structure in multidimensions and the identification of an associated tau-function. The obtained special solutions can be identified with open boundary problems of the associated Toda-type systems, and have interesting application to the construction of periodic solutions.Comment: 24 pages, 5 figure

Search for Small Trans-Neptunian Objects by the TAOS Project

The Taiwan-America Occultation Survey (TAOS) aims to determine the number of small icy bodies in the outer reach of the Solar System by means of stellar occultation. An array of 4 robotic small (D=0.5 m), wide-field (f/1.9) telescopes have been installed at Lulin Observatory in Taiwan to simultaneously monitor some thousand of stars for such rare occultation events. Because a typical occultation event by a TNO a few km across will last for only a fraction of a second, fast photometry is necessary. A special CCD readout scheme has been devised to allow for stellar photometry taken a few times per second. Effective analysis pipelines have been developed to process stellar light curves and to correlate any possible flux changes among all telescopes. A few billion photometric measurements have been collected since the routine survey began in early 2005. Our preliminary result of a very low detection rate suggests a deficit of small TNOs down to a few km size, consistent with the extrapolation of some recent studies of larger (30--100 km) TNOs.Comment: 4 pages, 3 figures, IAU Symposium 23

HST, radio and infrared observations of 28 3CR radio galaxies at redshift z ~ 1: I. Old stellar populations in central cluster galaxies

Hubble Space Telescope images of 3CR radio galaxies at redshifts 0.6 < z < 1.8 have shown a remarkable variety of structures, generally aligned along the radio axis, indicating that the radio source strongly influences the optical appearance of these galaxies. In this paper we investigate the host galaxies underlying this aligned emission, combining the HST data with ground-based infrared images. An investigation of the spectral energy distributions of the galaxies shows that the contribution of the aligned blue component to the K--band light is generally small (about 10%). The radial intensity profiles of the galaxies are well matched at radii <~ 35 kpc by de Vaucouleurs' law, demonstrating that the K--band light is dominated by that of an elliptical galaxy. There is no evidence for a nuclear point source, in addition to the de Vaucouleurs profile, with a contribution >~15% of the total K--band flux density, except in two cases, 3C22 and 3C41. Large characteristic radii are derived, indicating that the 3CR galaxies must be highly evolved dynamically, even at a redshift of one. At radii > 35 kpc, a combined galaxy profile clearly shows an excess of emission reminiscent of cD--type halos. This supports other independent evidence for the hypothesis that the distant 3CR galaxies lie in moderately rich (proto--)clusters. Since the nearby FR II galaxies in the 3CR catalogue lie in more diffuse environments and do not possess cD halos, the galactic environments of the 3CR galaxies must change with redshift. The K-z relation of the 3CR galaxies cannot, therefore, be interpreted using a standard `closed-box, passive stellar evolution' model. We offer a new interpretation, and compare the model with the K-z relations of lower power radio galaxies and brightest cluster galaxies. (abridged)Comment: 21 pages including 13 figures, LaTeX. To appear in MNRA

Quantifying Lipid Contents in Enveloped Virus Particles with Plasmonic Nanoparticles

Phosphatidylserine (PS) and monosialotetrahexosylganglioside (GM1) are examples of two host-derived lipids in the membrane of enveloped virus particles that are known to contribute to virus attachment, uptake, and ultimately dissemination. A quantitative characterization of their contribution to the functionality of the virus requires information about their relative concentrations in the viral membrane. Here, a gold nanoparticle (NP) binding assay for probing relative PS and GM1 lipid concentrations in the outer leaflet of different HIV-1 and Ebola virus-like particles (VLPs) using sample sizes of less than 3 × 106 particles is introduced. The assay evaluates both scattering intensity and resonance wavelength, and determines relative NP densities through plasmon coupling as a measure for the target lipid concentrations in the NP-labeled VLP membrane. A correlation of the optical observables with absolute lipid contents is achieved by calibration of the plasmon coupling-based methodology with unilamellar liposomes of known PS or GM1 concentration. The performed studies reveal significant differences in the membrane of VLPs that assemble at different intracellular sites and pave the way to an optical quantification of lipid concentration in virus particles at physiological titers.NIH grants RO1CA138509 (B.M.R.), RO1A1064099 (S. G., and 1R56Al104393 (B.M.R. and S. G.; Ethan Edmonds support (CHE 1156666

The clinical effectiveness and cost-effectiveness of point-of-care tests (CoaguChek system, INRatio2 PT/INR monitor and ProTime Microcoagulation system) for the self-monitoring of the coagulation status of people receiving long-term vitamin K antagonist therapy, compared with standard UK practice : systematic review and economic evaluation

Funding The National Institute for Health Research Health Technology Assessment programme.Peer reviewedPublisher PD

Ubiquitin, a central component of selective cytoplasmic proteolysis, is linked to proteins residing at the locus of non-selective proteolysis, the vacuole

Ubiquitin, an evolutionary highly conserved protein, is known to be involved in selective proteolysis in the cytoplasm. Here we show that ubiquitin-protein conjugates are also found in the yeast vacuole. Mutants defective in the major vacuolar endopeptidases, proteinase yscA and yscB, lead to accumulation of ubiquitin-protein conjugates in this cellular organelle.

Looking to the future: Framing the implementation of interprofessional education and practice with scenario planning

Background: Adapting to interprofessional education and practice requires a change of perspective for many health professionals. We aimed to explore the potential of scenario planning to bridge the understanding gap and framing strategic planning for interprofessional education (IPE) and practice (IPP), as well as to implement innovative techniques and technology for large‑group scenario planning. Methods: A full‑day scenario planning workshop incorporating innovative methodology was designed and offered to participants. The 71 participants included academics from nine universities, as well as service providers, government, students and consumer organisations. The outcomes were evaluated by statistical and thematic analysis of a mixed method survey questionnaire. Results: The scenario planning method resulted in a positive response as a means of collaboratively exploring current knowledge and broadening entrenched attitudes. It was perceived to be an effective instrument for framing strategy for the implementation of IPE/IPP, with 81 percent of respondents to a post‑workshop survey indicating they would consider using scenario planning in their own organisations. Discussion: The scenario planning method can be used by tertiary academic institutions as a strategy in developing, implementing and embedding IPE, and for the enculturation of IPP in practice settings.Government of Western Australia, Department of Health

Hydroxide catalysis bonding for astronomical instruments

Hydroxide catalysis bonding (HCB) as a jointing technique has been under development for astronomical applications since ∼1998 (patented by D.-H. Gwo). It uses an aqueous hydroxide solution to form a chemical bond between oxide or oxidisable materials (e.g., SiO2, sapphire, silicon and SiC). It forms strong, extremely thin bonds, and is suitable for room temperature bonding, precision alignment, operation in ultra-low vacuum and down to temperatures of 2.5 K. It has been applied in the NASA satellite mission Gravity Probe B and in the ground-based gravitational wave (GW) detector GEO600. It will soon fly again on the ESA LISA Pathfinder mission and is currently being implemented in the Advanced LIGO and Virgo ground-based GW detectors. This technique is also of considerable interest for use in other astronomical fields and indeed more broadly, due to its desirable, and adjustable, combination of properties. This paper gives an overview of how HCB has been and can be applied in astronomical instruments, including an overview of the current literature on the properties of hydroxide catalysis bonds

Decade time-scale modulation of low mass X-ray binaries

Regular observations by the All Sky Monitor aboard the Rossi X-ray Timing Explorer satellite have yielded well-sampled light-curves with a time baseline of over ten years. We find that up to eight of the sixteen brightest persistent low mass X-ray binaries show significant, possible sinusoidal, variations with periods of order ten years. We speculate on its possible origin and prevalence in the population of low mass X-ray binaries and we find the presence of a third object in the system, or long-period variability intrinsic to the donor star, as being attractive origins for the X-ray flux modulation we detect. For some of the objects in which we do not detect a signal, there is substantial short-term variation which may hide modest modulation on long time-scales. Decade time-scale modulations may thus be even more common.Comment: 8 pages, 4 figures, 2 tables. Accepted by MNRA