Vegetation and ghost crabs in coastal dunes as indicators of putative stressors from tourism

Coastal dunes provide important ecosystem services and are susceptible to human disturbance such as vehicle traffic and human trampling. Notwithstanding, on several Australian beaches dunes serves as camping areas, where camping sites are located on the primary dunes landwards of the foredunes. Because these activities have the potential to impact on the biota of the foredunes directly adjoining the camping zones, sustainable management of dunes for multiple uses requires that putative impacts are identified. Consequently, we quantified: (1) effects of dune camping on the vegetation in the foredunes abutting the camping zones, (2) ghost crab (Ocypode cordimana) abundance, distribution, body size, and body condition as biological indicators of human stressors, and (3) the degree to which habitat attributes are correlated with ghost crab abundance. Two percent of the foredune surface was disturbed by human activity (vehicle tracks, trampling, dog prints, litter). Camping in the primary dunes had some minor effects on the vegetation of the foredunes, but widespread changes in plant assemblages were not detected. Ghost crabs were attracted to camp sites, significantly changing their distribution across the dune field and increasing their body condition near camp sites—presumably a trophic subsidy from food scraps. Except for vegetation height which had a positive influence on crab density, there were no other strong and consistent predictors of ghost crab density either in terms of physical habitat attributes (e.g. dune width and height) or vegetation characteristics (e.g. plant cover, diversity). Because coastal managers must increasingly reconcile multiple uses of the environment with its protection, robust data on the type, extent and magnitude of impacts are critical to formulate efficient management strategies for dunes. Monitoring the efficacy of such strategies requires robust indicators, and we show that ghost crabs may be good candidate species for this.     

Strontium Diffusion in Magnetron Sputtered Gadolinia‐Doped Ceria Thin Film Barrier Coatings for Solid Oxide Fuel Cells

Strontium (Sr) diffusion in magnetron sputtered gadolinia‐doped ceria (CGO) thin films is investigated. For this purpose, a model system consisting of a screen printed (La,Sr)(Co,Fe)O_3?δ (LSCF) layer, and thin films of CGO and yttria‐stabilized zirconia (YSZ) is prepared to simulate a solid oxide fuel cell. This setup allows observation of Sr diffusion by observing SrZrO₃ formation using X‐ray diffraction while annealing. Subsequent electron microscopy confirms the results. This approach presents a simple method for assessing the quality of CGO barriers without the need for a complete fuel cell test setup. CGO films with thicknesses ranging from 250 nm to 1.2 μm are tested at temperatures from 850 °C to 1000 °C which yields an in‐depth understanding of Sr diffusion through CGO thin films that may be of high scientific and technical interest for implementation of novel fuel cell materials. Sr is found to diffuse along column/grain boundaries in the CGO films but by modifying the film thickness and microstructure the breaking temperature of the barrier can be increased.     

Dihydrotestosterone blocks fetal lung fibroblast-pneumonocyte factor at a pretranslational level

Fibroblast pneumonocyte factor (FPF) synthesis by fetal rat lung fibroblasts is augmented during gestation in the presence of cortisol. The control and cortisol-augmented levels of FPF production, as determined by FPF ability to stimulate saturated phosphotidylcholine synthesis by lung epithelial Type II cells, is delayed during development in fibroblasts derived from male fetuses as compared to those derived from female fetuses. The mechanism by which this delay occurs has been addressed. Pregnant rats treated in vivo with dihydrotestosterone (DHT) showed decreased FPF activity from control or cortisol-treated fibroblasts derived from 20-day-old male or female fetuses. In vitro translated proteins of size-fractionated lung RNA from 19-day-old fibroblasts that were pretreated with DHT in vitro showed decreased FPF activity compared to nontreated samples. This decreased FPF activity was present even if the DHT-pretreated cells were stimulated with cortisol prior to RNA preparation. Using a mouse model of testicular feminization that contains no receptors for androgens showed no change in the cortisol augmented FPF activity when the fibroblasts were pretreated with DHT. These data taken together suggest that the delayed FPF production of male-derived lung fibroblasts is a physiologic process which requires androgen receptors, and the mechanism by which androgens inhibit FPF production appears to affect events occurring mainly at a pretranslational level.     

Improving macromolecular electrostatics calculations.

Electrostatic interactions play a key role in many aspects of protein engineering. Consequently, much effort has been put into the design of software for calculating electrostatic fields around macromolecules. We show that optimization of hydrogen bonding networks can improve both the results of pK(a) calculations and the results of electrostatic calculations performed by commonly used programs such as DelPhi. Further optimization can often be achieved by flipping the side chains of asparagine, histidine and glutamine around their chi2, chi2 and chi3 torsion angles, respectively, when this improves the local hydrogen bonding network. These optimizations are applied to some well characterized proteins: BPTI, hen egg white lysozyme and superoxide dismutase. A search for flipped residues in the PDB revealed that significant improvements in electrostatic calculations in or near the active site of enzymes can be expected for about one quarter of all enzymes in the PDB.     

Decreased Number of Benzodiazepine Receptors in Frontal Cortex of Rat Brain Following Long-Term Lithium Treatment

Chronic administration of lithium led to a decreased number of benzodiazepine receptors (ca. 20%) in frontal cortex of rat brain, whereas no change was observed in the binding characteristics in the remaining part of the cortex and in the hippocampus and the cerebellum. Long-term lithium treatment did not change the binding of [3H]lysergic acid diethylamide and [3H]quinuclidinyl benzilate to membranes of various brain regions in the rat. We concluded that the effect of lithium on the benzodiazepine receptor is brain region specific and cannot be explained as a consequence of a reduced gamma-aminobutyric acid-ergic stimulation of benzodiazepine receptor, as the change in receptor binding was due to a change in the number of receptors rather than in the affinity constant.     

AIDS awareness among rural Utah physicians.

Studies of physicians'' attitudes and knowledge of the acquired immunodeficiency syndrome (AIDS) and the clinical precautions they take against exposure to the human immunodeficiency virus (HIV) have focused on urban physicians. To determine rural physicians'' knowledge and attitudes about AIDS, a questionnaire was mailed to 321 physicians practicing in rural Utah. Of the 169 physicians who completed questionnaires, 96% thought that their community or area of service had only a minor or no problem with AIDS; 89%, however, thought that their chance of seeing a patient who was HIV-positive was fair to moderate. Of the 169 respondents, 3% were not sure whether they would even treat a patient who had AIDS, 67% said they would, and 30% said they would not. Although all physicians are at risk of seeing a patient who has had exposure to HIV and other blood-borne diseases such as hepatitis B, only 55% of the respondents felt a need to take clinical precautions to prevent their exposure to the virus. Our study shows the need for all rural Utah physicians to reevaluate their risk of exposure to HIV, to increase precautionary measures for their own protection, to consider the ethical responsibility of treating AIDS patients, and to take a more active role in teaching their patients how to protect themselves from exposure to the virus.     

Sucrose metabolism in cold-stored potato tubers with decreased expression of sucrose phosphate synthase

Transfer of potato tubers to low temperature leads after 2–4 d to a stimulation of sucrose synthesis, a decline of hexose-phosphates and a change in the kinetic properties, and the appearance of a new form of sucrose phosphate synthase (SPS). Antisense and co-suppression transformants with a 70–80% reduction in SPS expression have been used to analyse the contribution of SPS to the control of cold sweetening. The rate of sucrose synthesis in cold-stored tubers was investigated by measuring the accumulation of sugars, by injecting labelled glucose of high specific activity into intact tubers, and by providing 50 mol m^–3 labelled glucose to fresh tuber slices from cold-stored tubers. A 70–80% decrease of SPS expression resulted in a reproducible but non-proportional (10–40%) decrease of soluble sugars in cold-stored tubers, and a non-proportional (about 25%) inhibition of label incorporation into sucrose, increased labelling of respiratory intermediates and carbon dioxide, and increased labelling of glucans. The maximum activity of SPS is 50-fold higher than the net rate of sugar accumulation in wild-type tubers, and decreased expression of SPS in the transformants was partly compensated for increased levels of hexose-phosphates. It is concluded that SPS expression per se does not control sugar synthesis. Rather, a comparison of the in vitro properties of SPS with the estimated in vivo concentrations of effectors shows that SPS is strongly substrate limited in vivo . Alterations in the kinetic properties of SPS, such as occur in response to low temperature, will provide a more effective way to stimulate sucrose synthesis than changes of SPS expression.