IMMUNOELECTRON MICROSCOPIC STUDIES OF REGULATORY PEPTIDES IN THE NERVOUS-SYSTEM OF THE MONOGENEAN PARASITE, DICLIDOPHORA-MERLANGI

Specific antisera, directed against the highly conserved C-terminal hexapeptide amide of mammalian pancreatic polypeptide (PP) and the invertebrate peptide FMRFamide, have been used in conjunction with post-embedding, IgG-conjugated colloidal gold immunostaining to demonstrate peptide immunoreactivity at subcellular level in the nervous system of adult Diclidophora merlangi. Gold labelling revealed that immunoreactivity for PP and FMRFamide was localized exclusively in dense-cored vesicles occupying the majority of axons in the central nervous system. Double-labelling demonstrated an apparent co-localization of PP and FMRFamide in the same dense-cored vesicles. Antigen preabsorption experiments indicated cross-reactivity of the two antisera as unlikely, and that some if not all of the PP/FMRFamide immunostaining in the parasite was due to a neuropeptide F-like peptide.

GRILLOTIA ERINACEUS (CESTODA, TRYPANORHYNCHA) - LOCALIZATION OF NEUROACTIVE SUBSTANCES IN THE PLEROCERCOID, USING CONFOCAL AND ELECTRON-MICROSCOPIC IMMUNOCYTOCHEMISTRY

Indirect immunocytochemistry, in conjunction with confocal scanning laser microscopy and electron-microscopic immunogold labeling, has been used to localize neuropeptide and 5-hydroxytryptamine (5-HT) immunereactivities (IRs) in the plerocercoid (scolex and surrounding blastocyst) of the trypanorhynch tapeworm, Grillotia erinaceus. Antisera directed to two native cestode neuropeptides, neuropeptide F and the FMRFamide-related peptide, GNFFRFamide, were used to demonstrate the presence of a well-developed and extensive peptide-immunoreactive nervous system of central and peripheral elements in the juvenile scolex. Neuronal connectivity exists between the scolex and the surrounding blastocyst, in which there is a rich innervation of varicose fibers displaying peptide IR. Ultrastructurally, gold labeling of the peptide IR was found exclusively over the contents of dense secretory vesicles in the axons and somatic cytoplasm of neurons. Double-labeling experiments demonstrated an apparent colocalization of peptide IR, although the results of antigen preadsorption procedures indicated substantial cross-reactivity of the two antisera. A separate and well-differentiated 5-HT-immunoreactive nervous system, with a similar anatomical arrangement as the peptide-immunoreactive nervous system, is present in both the scolex and blastocyst (C) 1994 Academic Press, Inc.

Discovery of Main-Belt Comet P/2006 VW139 by Pan-STARRS 1

The main-belt asteroid (300163) 2006 VW139 (later designated P/2006 VW139) was discovered to exhibit comet-like activity by the Pan-STARRS1 (PS1) survey telescope using automated point-spread-function analyses performed by PS1's Moving Object Processing System. Deep follow-up observations show both a short (~10'') antisolar dust tail and a longer (~60'') dust trail aligned with the object's orbit plane, similar to the morphology observed for another main-belt comet (MBC), P/2010 R2 (La Sagra), and other well-established comets, implying the action of a long-lived, sublimation-driven emission event. Photometry showing the brightness of the near-nucleus coma remaining constant over ~30 days provides further evidence for this object's cometary nature, suggesting it is in fact an MBC, and not a disrupted asteroid. A spectroscopic search for CN emission was unsuccessful, though we find an upper limit CN production rate of Q CN 100 Myr, while a search for a potential asteroid family around the object reveals a cluster of 24 asteroids within a cutoff distance of 68 m s-1. At 70 m s-1, this cluster merges with the Themis family, suggesting that it could be similar to the Beagle family to which another MBC, 133P/Elst-Pizarro, belongs.

Degradation of carbon disulphide (CS2) in soils and groundwater from a CS2 -contaminated site

This study is the first investigation of biodegradation of carbon disulphide (CS₂) in soil that provides estimates of degradation rates and identifies intermediate degradation products and carbon isotope signatures of degradation. Microcosm studies were undertaken under anaerobic conditions using soil and groundwater recovered from CS₂-contaminated sites. Proposed degradation mechanisms were validated using equilibrium speciation modelling of concentrations and carbon isotope ratios. A first-order degradation rate constant of 1.25 × 10-2 h-1 was obtained for biological degradation with soil. Carbonyl sulphide (COS) and hydrogen sulphide (H₂S) were found to be intermediates of degradation, but did not accumulate in vials. A 13C/12C enrichment factor of -7.5 ± 0.8 ‰ was obtained for degradation within microcosms with both soil and groundwater whereas a 13C/12C enrichment factor of -23.0 ± 2.1 ‰ was obtained for degradation with site groundwater alone. It can be concluded that biological degradation of both CS2-contaminated soil and groundwater is likely to occur in the field suggesting that natural attenuation may be an appropriate remedial tool at some sites. The presence of biodegradation by-products including COS and H₂S indicates that biodegradation of CS₂ is occurring and stable carbon isotopes are a promising tool to quantify CS₂ degradation.

Ethanol (C2H5OH) spray of sub-micron droplets for laser driven negative ion source

Liquid ethanol (C₂H₅OH) was used to generate a spray of sub-micron droplets. Sprays with different nozzle geometries have been tested and characterised using Mie scattering to find scaling properties and to generate droplets with different diameters within the spray. Nozzles having throat diameters of 470 µm and 560 µm showed generation of ethanol spray with droplet diameters of (180 ± 10) nm and (140 ± 10) nm, respectively. These investigations were motivated by the observation of copious negative ions from these target systems, e.g., negative oxygen and carbon ions measured from water and ethanol sprays irradiated with ultra-intense (5 × 1019 W/cm2), ultra short (40 fs) laser pulses. It is shown that the droplet diameter and the average atomic density of the spray have a significant effect on the numbers and energies of accelerated ions, both positive and negative. These targets open new possibilities for the creation of efficient and compact sources of different negative ion species.

Microscopic theory for random processes in weakly-coupled open systems

In order to relate macroscopic random motion (described e.g. by Langevin-type theories) to microscopic dynamics, we have undertaken the derivation of a Fokker-Planck-type equation from first microscopic principles. Both subsystems are subject to an external force field. Explicit expressions for the diffusion and drift coefficients are obtained, in terms of the field.

Has habitat heterogeneity promoted phenotypic and ecological sub-structuring among a Coregonus lavaretus population in a large Scottish lake?

Differences in stable-isotope values, morphology and ecology in whitefish Coregonus lavaretus were investigated between the three basins of Loch Lomond. The results are discussed with reference to a genetic investigation to elucidate any substructuring or spawning site fidelity. Foraging fidelity between basins of Loch Lomond was indicated by delta 13C and delta 15N values of C. lavaretus muscle tissue. There was, however, no evidence of the existence of sympatric morphs in the C. lavaretus population. A previous report of two C. lavaretus 'species' in Loch Lomond probably reflects natural variation between individuals within a single mixed population.

Generation of a quasi-monoergetic proton beam from laser-irradiated sub-micron droplets

Proton bursts with a narrow spectrum at an energy of (2.8 +/- 0.3 MeV) are accelerated from sub-micron water spray droplets irradiated by high-intensity (similar to 5 x 10(19)W/cm(2)), high-contrast (similar to 10(10)), ultra-short (40 fs) laser pulses. The acceleration is preferentially in the laser propagation direction. The explosion dynamics is governed by a residual ps-scale laser pulse pedestal which "mildly" preheats the droplet and changes its density profile before the arrival of the high intensity laser pulse peak. As a result, the energetic electrons extracted from the modified target by the high-intensity part of the laser pulse establish an anisotropic electrostatic field which results in anisotropic Coulomb explosion and proton acceleration predominantly in the forward direction. Hydrodynamic simulations of the target pre-expansion and 3D particle-in-cell simulations of the measured energy and anisotropy of the proton emission have confirmed the proposed acceleration scenario. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4731712]

Electron refluxing and K-shell line emission from Ti foils irradiated with sub-picosecond laser pulses at 527nm

We present data on emission of K-shell radiation from Ti foils irradiated with subpicosecond pulses of second harmonic radiation (527 nm) from the TARANIS laser system at intensities of up to 1018 Wcm-2. The data are used to demonstrate that a resonance absorption type mechanism is responsible for absorption of the laser light and to estimate fast electron temperatures of 30–60 keV that are in broad agreement with expectation from models of absorption for a steep density gradient. Data taken with resin-backed targets are used to demonstrate clear evidence of electron refluxing even at the modest fast electron temperatures inferred.