Larval Development of the Mangrove Fiddler Crab Austruca albimana (Kossmann, 1877) (Crustacea: Brachyura: Ocypodidae) Under Laboratory Conditions.

Larvae of the mangrove fiddler crab Austruca albimana (Kossmann, 1877), hatched from an ovigerous female collected from the mangroves of Sumariat, Jazan Province, Saudi Arabia in the southern Red Sea, were reared in the laboratory. Four zoeal and a megalopal stages were recorded, and their morphological features are described herein for the first time. The setations of the cephalothoracic appendages of the zoeas of A. albimana and their congeners exhibit several variations that help differentiate larvae of this genus easily from other meroplankton. However, a character of phylogenetic significance -minute spines on the forks of the telson of pleon -is common to larvae of this genus. These minute spines were studied with the aid of scanning electron microscope images. There were five common morphological features between A. albimana and other fiddler crab megalope, including Minuca burgersi, Leptuca uruguayensis and Leptuca thayeri. These features were a deflexed front, rounded to obtuse frontal margin, seven-segmented antennal flagellum, unsegmented endopod of maxilla and three cincinnuli on the endopods of pleopods. Two zoeal morphological features described in this study and other studies (i.e., the absence of lateral spines on carapace [vs. their presence in species of Uca, Afruca and Ocypode in the Ocypodinae] and the presence of a maximum of four pairs of inner setae on the telson of pleon [vs. presence of more than four pairs of setae in species of Uca, Afruca and Ocypode]) support the taxonomic amendment of transferring Uca spp. and Afruca spp. crabs from Gelasiminae to Ocypodinae.

Effect of varenicline on aspects of inhibitory control in smokers.

RATIONALE: Varenicline, a partial agonist at α4ß2 nicotinic receptors (nAChRs) aids smoking cessation by reducing craving. Successful quitting may be associated with greater inhibitory control but the effectiveness of varenicline in this regard is unknown. OBJECTIVES: This study aimed to investigate the effect of varenicline on aspects of inhibitory control in smokers. METHODS: A double-blind, placebo-controlled study investigating the effect of varenicline 1 mg (or matched placebo) in satiated and abstinent smokers. Tests included Rapid Visual Information Processing (RVIP), Stop-Signal (SS), Prospective Memory (PM) and the Cambridge Gambling Task (CGT). RESULTS: Smoking enhanced RVIP accuracy and latency to respond. Varenicline did not alter RVIP performance, nor the effect of smoking, suggesting that these effects were unrelated to α4ß2 nAChRs. Smoking increased the number of errors during SS and increased the stop latency, indicating that smoking decreased inhibitory control. Varenicline partially mimicked this effect of smoking but also reduced the smoking-induced increase, indicating a role for α4ß2 nAChRs. Likewise, smoking increased the number of points bet following a win during CGT and varenicline blocked this effect. There was no effect of smoking or varenicline on PM target detection per se. However, smoking protected the target detection rate in the ongoing task when a concurrent intention was introduced. Varenicline improved response speed in both satiated and abstinent smokers. CONCLUSIONS: Some aspects of inhibitory control may be mediated by α4ß2-related mechanisms and blockade of smoking-induced disinhibition may contribute towards the action of varenicline as an aid to smoking cessation.

Mechanisms of attention to conditioned stimuli predictive of a cigarette outcome.

Attention to stimuli associated with a rewarding outcome may be mediated by the incentive motivational properties that the stimulus acquires during conditioning. Other theories of attention state that the prediction error (the discrepancy between the expected and the actual outcome) during conditioning guides attention; once the outcome is fully predicted, attention should be abolished for the conditioned stimulus. The current study examined which of these mechanisms is dominant in conditioning when the outcome is highly rewarding. Allocation of attention to stimuli associated with cigarettes (the rewarding outcome) was tested in 16 smokers, who underwent a classical conditioning paradigm, where abstract visual stimuli were paired with a tobacco outcome. Stimuli were associated with 100% (stimulus A), 50% (stimulus B), or 0% (stimulus C) probability of receiving tobacco. Attention was measured using an eye-tracker device, and the appetitive value of the stimuli was measured with subjective pleasantness ratings during the conditioning process. Dwell time bias (duration of eye gaze) was greatest overall for the A stimulus, and increased over conditioning. Attention to stimulus A was dependent on the ratings of pleasantness that the stimulus evoked, and on the desire to smoke. These findings appear to support the theory that attention for conditioned stimuli is dominated by the incentive motivational qualities of the outcome they predict, and implicate a role for attention in the maintenance of addictive behaviours like smoking.

Mechanisms of attention for appetitive and aversive outcomes in Pavlovian conditioning.

Different mechanisms of attention controlling learning have been proposed in appetitive and aversive conditioning. The aim of the present study was to compare attention and learning in a Pavlovian conditioning paradigm using visual stimuli of varying predictive value of either monetary reward (appetitive conditioning; 10p or 50p) or blast of white noise (aversive conditioning; 97 dB or 102 dB). Outcome values were matched across the two conditions with regard to their emotional significance. Sixty-four participants were allocated to one of the four conditions matched for age and gender. All participants underwent a discriminative learning task using pairs of visual stimuli that signalled a 100%, 50%, or 0% probability of receiving an outcome. Learning was measured using a 9-point Likert scale of expectancy of the outcome, while attention using an eyetracker device. Arousal and emotional conditioning were also evaluated. Dwell time was greatest for the full predictor in the noise groups, while in the money groups attention was greatest for the partial predictor over the other two predictors. The progression of learning was the same for both groups. These findings suggest that in aversive conditioning attention is driven by the predictive salience of the stimulus while in appetitive conditioning attention is error-driven, when emotional value of the outcome is comparable.

In vitro comparison of antimicrobial activity of iodine and silver dressings against biofilms.

OBJECTIVE: To compare the antimicrobial effectiveness of silver- and iodine-containing wound dressings against preformed mature biofilms of pathogenic wound bacteria grown in vitro. METHOD: Biofilms of Pseudomonas aeruginosa and Staphylococcus aureus were grown within an in vitro flat bed perfusion biofilm model. Mature biofilms were removed and exposed to wound dressings containing either silver or iodine (Aquacel Ag and Iodozyme) within a static diffusion method, for up to 24 hours. This method was designed to reflect certain key features that determine antimicrobial activity within the wound. The numbers of viable bacteria surviving in the biofilms were determined at set time intervals over the test period. RESULTS: Both test dressings exerted an antimicrobial effect against the target species biofilms, although the iodine dressing was more efficacious under the experimental conditions employed. CONCLUSION: There are large and potentially significant differences (as measured in vitro) in the effectiveness of wound dressings containing broad-spectrum antimicrobial agents such as silver and iodine against specific types of bacterial biofilms.

In vitro method to assess the antimicrobial activity and potential efficacy of novel types of wound dressings.

AIMS: To develop a simple, reproducible in vitro static diffusion method using cellulose disks and defined species to test antimicrobial efficacy of wound dressings. METHODS AND RESULTS: Cellulose disks were inoculated by immersion in cell suspensions of target species Staphylococcus epidermidis, Candida albicans and Fusobacterium nucleatum. Test and control wound dressings were cut into equal sized squares (25 x 25 mm) and applied to the surface of 10-mm thick tryptone yeast extract agar on test beds. Following a 2-h equilibration period, inoculated cellulose disks were inserted (one per dressing) at the interface between dressing and agar surface and a small weight applied over each square. At various sampling times, disks were removed and surviving cells enumerated by viable counts. Disk to disk variation for microbial loading was assessed using S. epidermidis for both initial (n = 16) and standard treatment (n = 16) conditions. The coefficient of variation was low (<5%) indicating good reproducibility for cell loading and treatment position on the test bed. Replicate assays (n = 6) using S. epidermidis and oxyzyme gels produced similar kill rates with low scatter (R2 > 0.9) indicating good reproducibility between assays. Significant differences (P < 0.05) in kill rates were observed for different target species, types of dressing and test bed conditions (+/-blood and nutrients). CONCLUSIONS: The method is reproducible and useful in tracking the death kinetics of test species, enabling the comparison of different types of dressing. SIGNIFICANCE AND IMPACT OF THE STUDY: The reported method has significant advantages over established test procedures; it can be applied equally across a wide range of target species (including anaerobes and yeasts), a wide range of conditions, and different types of surface dressings, including those relying upon oxygen diffusion.

Production of human tissue factor using the Pichia pastoris expression system.

Tissue factor plays an important role in the initiation of the blood coagulation cascade resulting in the formation of a fibrin clot. The extracellular domain of human tissue factor has been expressed in the protease-deficient strain of the methylotrophic yeast Pichia pastoris, SMD1168. Tissue factor was expressed with a human influenza hemagglutinin tag fused at the C-terminus under control of the regulatory sequences from the Pichia AOX1 gene. Expressed protein was secreted in a soluble form at levels of up to 10 mg L-1 and correct processing of the PHO1 signal sequence was confirmed by N-terminal amino acid sequence analysis. Tissue factor was produced in Pichia as three discrete forms which appeared as three bands in the range 37-45 kDa by SDS-PAGE. These were all recognized by an anti-tissue factor monoclonal antibody. Deglycosylation studies using Endo H showed that the three forms were the result of differences in glycosylation of the protein. The low levels of secreted proteins produced by P. pastoris make this an efficient host for producing biologically active recombinant tissue factor requiring little purification.

Inhibition and covalent modification of rape seed (Brassica napus) enoyl ACP reductase by phenylglyoxal.

The NADH-dependent enoyl-ACP reductase from oil seed rape (Brassica napus) was inactivated by treatment with phenylglyoxal, a reagent which specifically modifies arginine residues. The inhibition at various phenylglyoxal concentrations shows pseudo-first-order kinetics, with an apparent second-order rate constant of 14.2 M-1.min-1 for inactivation. The protective ability of several substrates and substrate analogues was investigated in order to ascertain if the inhibition was directed towards the active site of the enzyme. NADH and NAD+ did not protect but acyl carrier protein (ACP) and reduced coenzyme A, along with various derivatives, did protect. 9 microM ACP gave 35% protection from inactivation and 10 mM reduced coenzyme A gave 98% protection. The effectiveness of various subfragments of coenzyme A in protecting against inhibition indicates that the phosphate group is essential for preventing the binding of phenylglyoxal. The idea that phenylglyoxal is inhibiting by binding at the active site is further supported by the observation that the incorporation of 14C-labelled phenylglyoxal is directly related to the loss of activity. Extrapolation of the amount of label incorporated to give total inhibition shows that 4 mol of phenylglyoxal would be incorporated per mol of enzyme. This corresponds to the modification of two arginine side-chains with equal reactiveness towards the reagent. These results are consistent with there being two arginine residues either at the active site of the enzyme or in an environment which is protected from phenylglyoxal by a conformational change induced by coenzyme A binding.