Adhesion of Salmonella enterica var Enteritidis strains lacking fimbriae and flagella to rat ileal explants cultured at the air interface or submerged in tissue culture medium

Rat ileal air interface and submerged explant models were developed and used to compare the adhesion of Salmonella enterica var Enteritidis wild-type strains with that of their isogenic single and multiple deletion mutants. The modified strains studied were defective for fimbriae, flagella, motility or chemotaxis and binding was assessed on tissues with and without an intact mucus layer. A multiple afimbriate/aflagellate (fim(-)/fla(-)) strain, a fimbriate but aflagellate (fla(-)) strain and a fimbriate/flagellate but non-motile (mot(-)) strain bound significantly less extensively to the explants than the corresponding wild-type strains. With the submerged explant model this difference was evident in tissues with or without a mucus layer, whereas in the air interface model it was observed only in tissues,vith an intact mucus layer. A smooth swimming chemotaxis-defective (che(-)) strain and single or multiple afimbriate strains bound to explants as well as their corresponding wild-type strain. This suggests that under the present experimental conditions fimbriae were not essential for attachment of S. enterica var Enteritidis to rat ileal explants, However; the possession of active flagella did appear to be an important factor. in enabling salmonellae to penetrate the gastrointestinal mucus layer and attach specifically to epithelial cells.

Evolution of the modern Nile delta promontories: development of accretional features during shoreline retreat

The active accretional features that have developed along the modern Nile Delta promontories during shoreline retreat are analysed using topographic maps, remote imagery, ground and hydrographic surveys, together providing 15 time-slice maps (1922-2000) at Rosetta and 14 time-slice maps (1909-2000) at Damietta. Small double sandy spits developed and persisted at Rosetta between 1986 and 1991. At Damietta, a much larger single spit, 9 km long, formed approximately east of the mouth of the Damietta Nile branch between 1955 and 1972, although its source has now been depleted. Both the Rosetta and Damietta inlets are associated with submerged mouth bars that accumulated prior to the damming of the Nile, but that continue to contribute to local sedimentation problems, particularly at Rosetta. The development of the active accretional features along the Nile promontories reflects a combination of factors including sediment availability, transport pathways from source areas, a decrease in the magnitude of Nile flood discharges, as well as the impact of protective structures at the river mouths.

Terrestrial implications for the maritime geoarchaeological resource: A view from the Lower Palaeolithic

Stone tools and faunal remains have been recovered from the English Channel and the North Sea through trawling, dredging for aggregates, channel clearance, and coring. These finds highlight the potential for a maritime Lower Palaeolithic archaeological resource. It is proposed here that any Lower Palaeolithic artefacts, faunal remains, and sediments deposited in the maritime zone during dry, low-stand phases were once (and may still be) contextually similar to their counterparts in the terrestrial Lower Palaeolithic records of north-western Europe. Given these similarities, can interpretive models and analytical frameworks developed for terrestrial archaeology be profitably applied to an assessment of the potential value of any maritime resource? The terrestrial geoarchaeological resource for the Lower Palaeolithic is dominated by artefacts and ecofacts that have been fluvially reworked. The spatio-temporal resolution of these data varies from entire river valleys and marine isotope stages to river channel gravel bar surfaces and decadal timescales, thus supporting a variety of questions and approaches. However, the structure of the terrestrial resource also highlights two fundamental limitations in current maritime knowledge that can restrict the application of terrestrial approaches to any potential maritime resource: (i) how have the repetitive transgressions and regressions of the Middle and Late Pleistocene modified the terrace landforms and sediments associated with the river systems of the English Channel and southern North Sea basins?; and (ii) do the surviving submerged terrace landforms and fluvial sedimentary deposits support robust geochronological models, as is the case with the classical terrestrial terrace sequences? This paper highlights potential approaches to these questions, and concludes that the fluvial palaeogeography, Pleistocene fossils, and potential Lower Palaeolithic artefacts of the maritime geoarchaeological resource can be profitably investigated in future as derived, low-resolution data sets, facilitating questions of colonisation, occupation, demography, and material culture.

Recent habitat degradation in karstic Lake Uluabat, western Turkey: A coupled limnological-palaeolimnological approach

The Ramsar site of Lake Uluabat, western Turkey, suffers from eutrophication, urban and industrial pollution and water abstraction, and its water levels are managed artificially. Here we combine monitoring and palaeolimnological. techniques to investigate spatial and temporal limnological variability and ecosystem impact, using an ostracod and mollusc survey to strengthen interpretation of the fossil record. A combination of low invertebrate Biological Monitoring Working Party scores (<10) and the dominance of eutrophic diatoms in the modern lake confirms its poor ecological status. Palaeolimnological analysis of recent (last >200 yr) changes in organic and carbonate content, diatoms, stable isotopes, ostracods and molluscs in a lake sediment core (UL20A) indicates a 20th century trend towards increased sediment accumulation rates and eutrophication which was probably initiated by deforestation and agriculture. The most marked ecological shift occurs in the early 1960s, however. A subtle rise in diatom-inferred total phosphorus and an inferred reduction in submerged aquatic macrophyte cover accompanies a major increase in sediment accumulation rate. An associated marked shift in ostracod stable isotope data indicative of reduced seasonality and a change in hydrological input suggests major impact from artificial water management practices, all of which appears to have culminated in the sustained loss of submerged macrophytes since 2000. The study indicates it is vital to take both land-use and water management practices into account in devising restoration strategies. in a wider context, the results have important implications for the conservation of shallow karstic lakes, the functioning of which is still poorly understood. (c) 2008 Elsevier Ltd. All rights reserved.

Seed development, maturation and storage behaviour of Mimusops elengi L

Mass maturity (end of the seed-filling phase) occurred at about 72 days after flowering (DAF) in developing seeds of Mimusops elengi, at which time seed moisture content had declined to about 55%. The onset of ability to germinate was detected at 56 DAF and seeds showed 98% germination by 84 DAF. Tolerance of desiccation to 10% moisture content was first detected at 70 DAF and was maximal by 84 DAF. Delaying collection by a further 14 days to 98 DAF, when fruits began to be shed, reduced seed viability, particularly for seeds first dried to 10% moisture content. Hence the best time for seed collection appears to be about 14 days before fruits shed. In a separate investigation with six different seed lots, desiccation below about 8-12% moisture content reduced viability (considerably in some lots). The viability of dry seeds (below about 10% moisture content) stored hermetically was reduced at cool temperatures (5 degrees C and below), and none survived storage at sub-zero temperatures. The results suggest that Mimusops elengi shows intermediate seed storage behaviour and that the optimal hermetic seed storage environment is about 10% moisture content at 10 degrees C, while short-term, moist, aerated storage at high (40%) moisture content is also feasible.

Vacuum-induced bubble formation in liquid-tempered chocolate

Bubble inclusion is one of the fastest growing operations practiced in the food industry. A variety of aerated foods is currently available in supermarkets, and newer products are emerging all the time. This paper aims to combine knowledge on chocolate aeration with studies performed on bubble formation and dispersion characteristics. More specifically, we have investigated bubble formation induced by applying vacuum. Experimental methods to determine gas hold-up (volume fraction of air), bubble section distributions along specific planes, and chocolate rheological properties are presented. This study concludes that decreasing pressures elevate gas hold-up values due to an increase in the number of bubble nuclei being formed and release of a greater volume of dissolved gases. Furthermore, bubbles are observed to be larger at lower pressures for a set amount of gas because the internal pressure needs to be in equilibrium with the surrounding pressures. Temperature-induced changes to the properties of the chocolate have less of an effect on bubble formation. On the other hand, when different fats and emulsifiers are added to a standard chocolate recipe, milk fat was found to increase, significantly, the gas hold-up values and the mean bubble-section diameters. It is hypothesized that this behavior is related to the way milk fats, which contain different fatty acids to cocoa butter, crystallize and influence the setting properties of the final product. It is highlighted that apparent viscosity values at low shear rate, as well as setting behavior, play an important role in terms of bubble formation and entrainment.

Bubble-included chocolate: relating structure with sensory response

Bubbles impart a very unique texture, chew, and mouth feel to foods. However, little is known about the relationship between structure of such products and consumer response in terms of mouth-feel and eating experience. The objective of this article is to investigate the sensory properties of 4 types of bubble-containing chocolates, produced by using different gases: carbon dioxide, nitrogen, nitrous oxide, and argon. The structure of these chocolates were characterized in terms of (1) gas hold-up values determined by density measurements and (2) bubble size distribution which was measured by undertaking an image analysis of X-ray microtomograph sections. Bubble size distributions were obtained by measuring bubble volumes after reconstructing 3D images from the tomographic sections. A sensory study was undertaken by a nonexpert panel of 20 panelists and their responses were analyzed using qualitative descriptive analysis (QDA). The results show that chocolates made from the 4 gases could be divided into 2 groups on the basis of bubble volume and gas hold-up: the samples produced using carbon dioxide and nitrous oxide had a distinctly higher gas hold-up containing larger bubbles in comparison with those produced using argon and nitrogen. The sensory study also demonstrated that chocolates made with the latter were perceived to be harder, less aerated, slow to melt in the mouth, and having overall flavor intensity. These products were further found to be creamier than the chocolates made by using carbon dioxide and nitrous oxide; the latter sample also showed a higher intensity of cocoa flavor.

Adsorption of frog foam nest proteins at the air-water interface

The surfactant properties of aqueous protein mixtures ( ranaspumins) from the foam nests of the tropical frog Physalaemus pustulosus have been investigated by surface tension, two-photon excitation. uorescence microscopy, specular neutron reflection, and related biophysical techniques. Ranaspumins lower the surface tension of water more rapidly and more effectively than standard globular proteins under similar conditions. Two- photon excitation. uorescence microscopy of nest foams treated with fluorescent marker ( anilinonaphthalene sulfonic acid) shows partitioning of hydrophobic proteins into the air-water interface and allows imaging of the foam structure. The surface excess of the adsorbed protein layers, determined from measurements of neutron reflection from the surface of water utilizing H2O/D2O mixtures, shows a persistent increase of surface excess and layer thickness with bulk concentration. At the highest concentration studied ( 0.5 mg ml(-1)), the adsorbed layer is characterized by three distinct regions: a protruding top layer of similar to20 Angstrom, a middle layer of similar to30 Angstrom, and a more diffuse submerged layer projecting some 25 Angstrom into bulk solution. This suggests a model involving self-assembly of protein aggregates at the air-water interface in which initial foam formation is facilitated by specific surfactant proteins in the mixture, further stabilized by subsequent aggregation and cross-linking into a multilayer surface complex.

The monitoring of ecological quality and the classification of standing waters in temperate regions: a review and proposal based on a worked scheme for British waters

This paper reviews the ways that quality can be assessed in standing waters, a subject that has hitherto attracted little attention but which is now a legal requirement in Europe. It describes a scheme for the assessment and monitoring of water and ecological quality in standing waters greater than about I ha in area in England & Wales although it is generally relevant to North-west Europe. Thirteen hydrological, chemical and biological variables are used to characterise the standing water body in any current sampling. These are lake volume, maximum depth, onductivity, Secchi disc transparency, pH, total alkalinity, calcium ion concentration, total N concentration,winter total oxidised inorganic nitrogen (effectively nitrate) concentration, total P concentration, potential maximum chlorophyll a concentration, a score based on the nature of the submerged and emergent plant community, and the presence or absence of a fish community. Inter alia these variables are key indicators of the state of eutrophication, acidification, salinisation and infilling of a water body.

Mesolithic to Neolithic and medieval coastal environmental change: intertidal survey at Woolaston, Gloucestershire

At Woolaston on the western shores of the middle Severn Estuary c. 7 km upstream of Chepstow intertidal Holocene sediment exposures have been surveyed and the stratigraphic sequence established by coring and limited excavation. There are two main peats each with a submerged forest. An existing dendrochronological sequence for the Upper Submerged Forest has been extended and the preliminary results of pollen analysis from the peat sequence are summarised. A few flint flakes were found but were not stratified in the mid-Holocene sequence. There is evidence for late Mesolithic / early Neolithic burning episodes which may relate to human activity. Evidence is reported for Medieval activity and the extensive modification of drainage in this period is suggested.

The central European floods of August 2002: Part 1 - Rainfall periods and flood development

Record-breaking rainfall amounts and intensities were observed at several raingauges in central Europe during the first half of August 2002 (Fig. 1). They produced flash floods in small rivers in the Erz Mountains, the Bohemian Forest and in Lower Austria (see Fig. 2), followed by record-breaking floods of larger rivers fed from these areas. The Vltava submerged parts of the city of Prague on 13± 15 August, and subsequently the Elbe flooded parts of Dresden and further villages and towns located downstream. The gauge level of 9.40m measured at Dresden on 17 August 2002 is the highest level since 1275, exceeding the former maximum level of 8.77m recorded in 1845 (Grollmann and Simon 2002). Parts of the Danube catchment were also affected by severe flooding. There were 100 fatalities connected with the floods in central Europe, and the economic loss is estimated at 9 billion Euros for Germany (German government’s estimate), 3 billion Euros for Austria, and 2.5 billion Euros for the Czech Republic (estimates from Boyle 2002). The event thus replaced the European winter storm Lothar of December 1999 (Ulbrich et al. 2001) as the most expensive weather-related catastrophe in Europe in recent decades (see Cornford 2002). In this study, we give an overview of the exceptional rainfall experienced over wide areas on 12/13 August 2002, and the resulting floods. Further events during early August 2002, in particular the event on 6/7 August in Lower Austria, are briefly mentioned.

Optimizing mixing during the sponge cake manufacturing process

Sponge cakes have traditionally been manufactured using multistage mixing methods to enhance potential foam formation by the eggs. Today, use of all-in (single-stage) mixing methods is superseding multistage methods for large-scale batter preparation to reduce costs and production time. In this study, multistage and all-in mixing procedures and three final high-speed mixing times (3, 5, and 15 min) for sponge cake production were tested to optimize a mixing method for pilot-scale research. Mixing for 3 min produced batters with higher relative density values than did longer mixing times. These batters generated well-aerated cakes with high volume and low hardness. In contrast, after 5 and 15 min of high-speed mixing, batters with lower relative density and higher viscosity values were produced. Although higher bubble incorporation and retention were observed, longer mixing times produced better developed gluten networks, which stiffened the batters and inhibited bubble expansion during mixing. As a result, these batters did not expand properly and produced cakes with low volume, dense crumb, and high hardness values. Results for all-in mixing were similar to those for the multistage mixing procedure in terms of the physical properties of batters and cakes (i.e., relative density, elastic moduli, volume, total cell area, hardness, etc.). These results suggest the all-in mixing procedure with a final high-speed mixing time of 3 min is an appropriate mixing method for pilot-scale sponge cake production. The advantages of this method are reduced energy costs and production time.