Polyplex-embedding in polyelectrolyte multilayers for gene delivery

In this work, incorporation of plasmid DNA, pre-complexed with PEI, into polyelectrolyte multilayers has been studied to further develop platforms for local gene delivery. Polyplex embedding in synthetic and naturally degradable architectures was efficient for transfection of human hepato-cellular carcinoma cells.     

Atom ordering in cuboctahedral Ni-Al nanoalloys

Energy calculations have been carried out on high-symmetry cuboctahedral Ni-Al nanoalloy clusters, of varying composition, with the interatomic interactions modelled by the Gupta many-body potential. Relaxations of cuboctahedral fragments cut from the bulk lattice of Ni₃Al, with 13-561 atoms, were undertaken, as were relaxations of high symmetry clusters with 55 and 147 atoms. The lowest energy isomers were found to be dominated by three factors: the tendency toward mixing due to the favourable energy of mixing, Δ_mixE; the size difference between nickel and aluminium; and the higher cohesive and surface energy of nickel compared to aluminium. The latter two factors favour Al-segregation to the surface. The most stable Ni:Al composition approaches 3:1 for larger clusters.     

Lingulid shell mediation in clay formation

Organophosphatic shells of the brachiopod Lingula squarniformis , collected from Scottish Lower Carboniferous shales and mudstones of intertidal to sublittoral provenance, have been studied to ascertain chemico-structural changes resulting from fossilization. Enough original shell has been preserved at ultrastructural and molecular levels to confirm that Carboniferous and Recent integuments are homologous with stratiform successions of apatitic to organic laminae forming rhythmic sets. One of the main organic constituents, the acidic, hydrophilic gel glycosaminoglycans (GAGs), is the dominant component towards the tops of rhythms. During fossilization of the Carboniferous shells, GAGs degraded incrementally without disturbing apatitic ultrastructures, and the spaces so created became partly filled with sheets of recrystal-lized apatite with some kaolinite or with books and plates of kaolinite. The kaolinite in the shells contrasts with the illite of the entombing sediments and suggests that degrading acidic GAGs mediated in clay formation in situ . The sediments also contain framboidal pyrite, which is virtually absent from the shells themselves but is usually even more abundant, with a greater range of trace metals, in the sedimentary fills of complete shells. This imbalance suggests mediation by another gel, the glycocalyx, secreted by the inner epithelium of the brachiopod mantle. The glycocalyx would have lined the shell interior and could have served as a sorption film for dissolved metals precipitated as compounds on decomposition of body tissue.     

The Ocruranus–Eohalobia group of small shelly fossils from the Lower Cambrian of Yunnan

Lower Cambrian phosphorite samples from Maotianshan, Yunnan Province, South China, yielded a variety of small shelly fossils. Sclerites of the second pre-trilobite faunal assemblage of Meishucun, the Paragbborilus-Siphogonuchites–Lapworthella association of Nemakit–Daldynian to Tommotían age, were dominant. They comprise previously unknown spine-bearing specimens of Ocruranus finial Liu, 1979, and new morphotypes of Eohalobia diandongensis Jiang, 1982. Well-preserved sclerites reveal a laminated, composite fine structure with marginal, incremental growth. Each lamella consists of radial series of minute growth elements. The shells are phosphatically preserved, but micropetrographic evidence from drill-core samples indicates calcium carbonate as primary shell material. In the light of this new evidence, Ocruranus–Eohalobia group fossils are interpreted as parts of coeloscleritophoran scleritomes.     

Endemic evolutionary radiation of Rhagada land snails (Pulmonata: Camaenidae) in a continental archipelago in northern Western Australia

In the Dampier Archipelago of Western Australia's Pilbara Region, several locally endemic, morphologically distinctive species of Rhagada land snails occur, contrasting with the morphologically conservative species with wider distributions on the adjacent mainland. To test alternative origins of this unusual local diversity in a continental archipelago, we examined sequences of the cytochrome oxidase subunit 1 and 16S mitochondrial genes in 22 described species and eight undescribed forms, including all known morphospecies from the Pilbara Region's Dampier Archipelago and adjacent mainland. Phylogenetic analyses consistently resolved four, deep clades within the Pilbara Region, with a mean sequence divergence of 15–18%. All but one of the species from the Dampier Archipelago formed one of the major clades, indicating that the morphological radiation in the archipelago evolved locally, rather than through multiple, relictual mainland lineages. Morphological divergence spanning almost that of the entire genus was within a subclade with sequence divergence < 4%, highlighting the disconnection between morphological diversification and levels of molecular genetic divergence. This in situ morphological radiation in the Dampier Archipelago, which transcends variation seen over much larger distances on the mainland, is unusual for a continental archipelago, and may relate to local heterogeneity of land forms. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 316–327.     

Biosorption of lead by cotton shells powder: Characterization and equilibrium modeling study

Lead (Pb) is a toxic heavy metal causing serious health risks to humans and animals. In the present study, cotton (Gossypium hirsutum L.) shells powder was used as adsorbent for the treatment of synthetic Pb-contaminated water. The batch scale biosorption capacity of cotton shells powder was evaluated to study the effects of Pb concentrations, adsorbent doses and contact time at constant pH (6) and temperature (25?°C). Results revealed that sorption of Pb increased (q?=?0.09–9.60?mg/g) with increasing Pb concentration (1–15?mg/L) and contact time (15–90?min) while decreasing adsorbent dose (1–0.1?g/100?mL). The maximum Pb removal (90%) was achieved at Pb concentration (1?mg/L), contact time (90?min) and adsorbent dose (1?g/100?mL). Freundlich isotherm model proved best fit for Pb sorption (R²?=?0.99). The cotton shells powder has microporous structure confirmed by SEM, and has BET surface area (45 m²/g) and pore size (2.3 µm). These surface moieties along with various functional groups (C-H, C-O, C=O, O-H, S=O) confirmed by FTIR analysis might involve in Pb removal by complexation and ion exchange mechanisms. The cotton shells powder biomass could be considered as promising adsorbent for the removal of Pb from contaminated water.     

Minor- and trace-element intra-shell variations in Santonian inoceramids (Basque-Cantabrian Basin,northern Spain): diagenetic and primary causes

Santonian deep- and platform-marine facies inoceramids from the Basque-Cantabrian Basin show clear saw-toothed intra-shell variations with respect to Mg/Ca, Sr/Ca, Na/Ca, Ba/Ca, Fe/Ca and Mn/Ca ratios. Under cathodoluminescence, the most luminescent zones in all the inoceramids present lower Mg/Ca and Sr/Ca (up to 48% and 35% lower values, respectively) and higher Fe/Ca and Mn/Ca ratios (up to 362% and 819% higher values, respectively), which is indicative of diagenetic modification. In contrast, the least luminescent zones show higher Mg/Ca and Sr/Ca ratios and lower Fe/Ca and Mn/Ca. These findings, along with the presence of frequent, well-correlated Mg/Ca, Sr/Ca and Na/Ca ratios, inversely related to Fe/Ca and Mn/Ca, in the weakest luminescent zones suggest major retention of the primary intra-shell variations in these zones. Moreover, Ba/Ca profiles, not connected with the general cathodoluminescence behaviour of the shells, also point towards partial retention of the primary patterns. The saw-toothed intra-shell variations are thought to be caused by the distinct geochemical signals acquired originally by the inoceramid alternating clear and dark growth lines. The deposition of the growth lines and thus the saw-toothed intra-shell variations may be mainly related to periodically changing palaeoenvironmental conditions, such as seawater temperature variations and phytodetritus rainfall. This interpretation is supported by the appearance of highly similar chemical saw-toothed variations in the extant shallow-marine Atrina rigida shell.     

Polyelectrolyte complexes as a tool for purification of plasmid DNA. Background and development

The demand for highly purified plasmids in gene therapy and plasmid-based vaccines requires large-scale production of pharmaceutical-grade plasmid. Plasmid DNA was selectively precipitated from a clarified alkaline lysate using the polycation poly(N,N'-dimethyldiallylammonium) chloride which formed insoluble polyelectrolyte complex (PEC) with the plasmid DNA. Soluble PECs of DNA with polycations have earlier been used for cell transformation, but now the focus has been on insoluble PECs. Both DNA and RNA form stable PECs with synthetic polycations. However, it was possible to find a range of salt concentration where plasmid DNA was quantitatively precipitated whereas RNA remained in solution. The precipitated plasmid DNA was resolubilised at high salt concentration and the polycation was removed by gel-filtration.     

Stable isotope records (O, C) of Jurassic aragonitic shells from England and NW Poland: palaeoecologic and environmental implications

Shells of fully marine Middle to Upper Jurassic molluscs from England and north-western Poland were analysed with respect to their stable isotope (δ¹⁸O, δ¹³C) compositions, and palaeoecological and environmental life conditions of these molluscs were inferred from them. Light microscopical and SEM inspection and an analysis of the minor element content (Fe, Mn, Mg, Sr) suggest rather unaltered isotope signals. The δ¹⁸O and δ¹³C values show a characteristic distribution among three groups of co-occurring organisms. Benthic (adult) bivalves generally preserved higher δ¹⁸O and δ¹³C values than ammonites, whereas planktic bivalve larvae tend to possess the lowest δ¹⁸O but higher δ¹³C than adult bivalves. As this distribution pattern is found in numerous horizons and sections of Bathonian to Kimmeridgian age in NW Poland and England, it is thought to reflect real palaeoenvironmental parameters. All observations can be incorporated in a single model that assumes (i) seasonally induced temperature stratification of the water column, (ii) a correlation between phytoplankton blooms and reproduction season of planktic-planktotrophic bivalves, and (iii) insignificant vital effects with respect to the δ¹³C in bivalves, but strong biological control in ammonites. In addition, the δ¹⁸O evolution suggests that the Late Bajocian to Middle/Late Bathonian and Early Oxfordian to Late Kimmeridgian were considerably warmer than the latest Bathonian to Late Callovian time interval. The oxygen isotopic records from other European regions indicate a similar pattern of long-term palaeotemperature evolution. The comparatively high water temperatures during the Callovian to Oxfordian of the Isle of Skye (NW Scotland) are enigmatic, however. In the Early Oxfordian, sea surface and bottom temperatures began to rise in continental Europe and England. These changes coincide with a south-westward drift of the West European crustal plate, but a causal relationship remains to be demonstrated.