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In euryhaline teleosts, osmoregulation is a fundamental and dynamic process that is essential for the maintenance of ion and water balance, especially when fish migrate between fresh water (FW) and sea water (SW) environments. The European eel has proved to be an excellent model species to study the molecular and physiological adaptations associated with this osmoregulatory plasticity. The life cycle of the European eel includes two migratory periods, the second being the migration of FW eels back to the Sargasso Sea for reproduction. Various anatomical and physiological changes allow the successful transition to SW. The aim of this study was to use a microarray approach to screen the osmoregulatory tissues of the eel for changes in gene expression following acclimation to SW. Tissues were sampled from fish at selected intervals over a 5-mo period following FW/SW transfer, and RNA was isolated. Suppressive subtractive hybridization was used for enrichment of differentially expressed genes. Microarrays comprising 6,144 cDNAs from brain, gill, intestine, and kidney libraries were hybridized with appropriate targets and analyzed; 229 differentially expressed clones with unique sequences were identified. These clones represented the sequences for 95 known genes, with the remaining sequences (59%) being unknown. The results of the microarray analysis were validated by quantification of 28 differentially expressed genes by Northern blotting. A number of the differentially expressed genes were already known to be involved in osmoregulation, but the functional roles of many others, not normally associated with ion or water transport, remain to be characterized.

A study of the electrodeposition ͑ED͒ of silicon from silicon halides in a nonaqueous electrolyte solution is described. In spite of the use of nonoxidizing electrolytes, the electrodeposits usually become oxidized on air exposure. In similarity to other work, it is postulated that this is due to the deposit being formed with a spongy or honeycombed morphology. However, secondary neutral mass spectrometry ͑SNMS͒ and X-ray diffraction ͑XRD͒ analyses show that a region of the deposit close to the substrate has sufficient purity for semiconductor properties. This is verified by observing diode behavior at junctions of the deposited layers and mercury contacts. For deposition on crystal silicon substrates, it proved possible to form a p-doped ED-Si/c-Si heterojunction which showed a solar cell conversion efficiency of 1.8%. This is probably the first photovoltaic cell which uses electrodeposited silicon in a heterojunction.

The state-of-the-art in depth-averaged mathematical modelling of 3-D coastal morphology is described for the medium-term morphodynamic model type, in which constituent models of waves, currents and sediment transport based on first physical principles are linked together to describe the time-evolution of the bed topography. Various aspects of the combined system of equations are discussed, such as its mathematical character, its inherent stability and its equilibrium state. The results of an intercomparison of different models are shown for two test cases and the potentials and limitations of the model concept are discussed.

SummaryWe retrospectively compared the changes in serum albumin concentration and colloid osmotic pressure between survivors and nonsurvivors of prolonged (Ն7 days) critical illness over a 2-year period from 1 July 1995. All patients had serum albumin measured daily, and colloid osmotic pressure measured 5 days a week, throughout their ICU admission. (survivors); p < 0.01]. Analysis of colloid osmotic pressure results showed no difference between the groups in mean, minimum or recovery mean. Regression analysis of mean colloid osmotic pressure and albumin revealed that albumin only contributed 17% of the colloid osmotic pressure in these patients. The similar decrease in albumin in nonsurvivors and survivors may reflect the acute inflammatory response and/or haemodilution. However, survivors showed an ability to increase serum albumin concentrations, possibly owing to resumption of synthesis. The colloid osmotic pressure varied little between or within either group of patients, possibly because of the use of artificial colloids. There was no relationship between death and colloid osmotic pressure.

BackgroundMany biomedical applications require the expression or production of therapeutic hetero-multimeric proteins/protein complexes: in most cases only accomplished by co-ordinated co-expression within the same cell. Foot-and-mouth disease virus 2A (F2A) and ‘2A-like’ sequences are now widely used for this purpose. Since 2A mediates a co-translational ‘cleavage’ at its own C-terminus, sequences encoding multiple proteins (linked via 2As) can be concatenated into a single ORF: a single transgene. It has been shown that in some cases, however, the cleavage efficiency of shorter versions of F2A may be inhibited by the C-terminus of certain gene sequences immediately upstream of F2A. This paper describes further work to optimise F2A for co-expression strategies.ResultsWe have inserted F2A of various lengths in between GFP and CherryFP ‘reporter’ proteins (in reciprocal or tandem arrangements). The co-expression of these proteins and cleavage efficiencies of F2As of various lengths were studied by in vitro coupled transcription and translation in rabbit reticulocyte lysates, western blotting of HeLa cell lysates and fluorescence microscopy.ConclusionsOptimal and suboptimal lengths of F2A sequences were identified as a result of detailed ‘fine-tuning’ of the F2A sequence. Based on our data and the model according to which 2A activity is a product of its interaction with the exit tunnel of the ribosome, we suggest the length of the F2A sequence which is not ‘sensitive’ to the C-terminus of the upstream protein that can be successfully used for co-expression of two proteins for biomedical applications.

HighlightsFMDV replication can be studied outwith high disease secure facilities.FMDV replicon genomes encoding GFP are replication competent.These FMDV replicon systems can be used to study replication by live-cell imaging/image analyses.

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