Resilience and elasticity of intertidal communities in response to harvesting of the alien mussel Mytilus galloprovincialis

Besides the direct impacts of exploitation on target species, indirect effects on non-target species are unavoidable and find expression in changes in community structure. We quantified the effects of experimental harvesting of Mytilus galloprovincialis on intertidal communities on the South African west coast. In the mid- and low-shore, four months of harvesting at intensities greater than F = 0.3 and F = 0.6 respectively, resulted in significant changes in community composition. These changes were driven by progressively greater spatial dominance by the macroalgae Cladophora flagelliformis, Porphyra capensis and Ulva species as harvesting intensity increased. Four months after cessation of harvesting, community structure had not recovered and even areas subjected to as little as F = 0.3 supported significantly altered communities in both zones. The fact that substantial community changes were induced by even low-intensity exploitation is indicative of low resilience to harvesting. The densities and cover of the dominant taxa returned to a pre-harvest state 16 months after the cessation of harvesting, but multivariate analyses indicated that the overall community composition required 32 months for Cover Letter full recovery. Although these communities displayed elasticity within three years, it is recommended that should a M. galloprovincialis fishery be established in the region, harvesting be implemented at a maximum intensity of F = 0.3. This approach would maximise yields and protect associated intertidal communities.     

Phosphatidylinositol-4-kinase type II alpha contains an AP-3-sorting motif and a kinase domain that are both required for endosome traffic

The adaptor complex 3 (AP-3) targets membrane proteins from endosomes to lysosomes, lysosome-related organelles and synaptic vesicles. Phosphatidylinositol-4-kinase type II alpha (PI4KIIalpha) is one of several proteins possessing catalytic domains that regulate AP-3-dependent sorting. Here we present evidence that PI4KIIalpha uniquely behaves both as a membrane protein cargo as well as an enzymatic regulator of adaptor function. In fact, AP-3 and PI4KIIalpha form a complex that requires a dileucine-sorting motif present in PI4KIIalpha. Mutagenesis of either the PI4KIIalpha-sorting motif or its kinase-active site indicates that both are necessary to interact with AP-3 and properly localize PI4KIIalpha to LAMP-1-positive endosomes. Similarly, both the kinase activity and the sorting signal present in PI4KIIalpha are necessary to rescue endosomal PI4KIIalpha siRNA-induced mutant phenotypes. We propose a mechanism whereby adaptors use canonical sorting motifs to selectively recruit a regulatory enzymatic activity to restricted membrane domains.     

EVIDENCE FOR INCREASES IN ANTARCTIC BLUE WHALES BASED ON BAYESIAN MODELLING

Antarctic blue whales ( Balaenoptera musculus intermedia ) are the largest and formerly most abundant blue whale subspecies, but were hunted to near extinction last century. Estimated whaling mortality was unsustainable from 1928 to 1972 (except during 1942–1944), depleting them from 239,000 (95% interval 202,000–311,000) to a low of 360 (150–840) in 1973. Obtaining statistical evidence for subsequent increases has proved difficult due to their scarcity. We fitted Bayesian models to three sighting series (1968–2001), constraining maximum rates of increase to 12% per annum. These models indicated that Antarctic blue whales are increasing at a mean rate of 7.3% per annum (1.4%–11.6%). Informative priors based on blue whale biology (4.3%, SD = 1.9%) and a Bayesian hierarchical meta-analysis of increase rates in other blue whale populations (−3%, SD = 11.6%), suggest plausible increase rates are lower (although the latter has wide intervals), but a meta-analysis of other mysticetes obtains similar rates of increase (6.7%, SD = 4.0%). Possible biases affecting the input abundance estimates are discussed. Although Antarctic blue whales appear to have been increasing since Sovier illegal whaling ended in 1972, they still need to be protected-their estimated 1996 population size, 1,700 (860–2,900), was just 0.7% (0.3%–1.3%) of the pre-exploitation level.     

Non-Faradaic electrochemical detection of protein interactions by integrated neuromorphic CMOS sensors

Electronic detection of the binding event between biotinylated bovine serum albumen (BSA) and streptavidin is demonstrated with the chemoreceptive neuron MOS (CnuMOS) device. Differing from the ion-sensitive field-effect transistors (ISFET), CnuMOS, with the potential of the extended floating gate determined by both the sensing and control gates in a neuromorphic style, can provide protein detection without requiring analyte reference electrodes. In comparison with the microelectrode arrays, measurements are gathered through purely capacitive, non-Faradaic interactions across insulating interfaces. By using a (3-glycidoxypropyl)trimethoxysilane (3-GPS) self-assembled monolayer (SAM) as a simple covalent link for attaching proteins to a silicon dioxide sensing surface, a fully integrated, electrochemical detection platform is realized for protein interactions through monotone large-signal measurements or small-signal impedance spectroscopy. Calibration curves were created to coordinate the sensor response with ellipsometric measurements taken on witness samples. By monitoring the film thickness of streptavidin capture, a sensitivity of 25ng/cm2 or 2A of film thickness was demonstrated. With an improved noise floor the sensor can detect down to 2ng/(cm2mV) based on the calibration curve. AC measurements are shown to significantly reduce long-term sensor drift. Finally, a noise analysis of electrochemical data indicates 1/f(alpha) behavior with a noise floor beginning at approximately 1Hz.     

Detection of viral bioagents using a shear horizontal surface acoustic wave biosensor

Viruses are of high medical and biodefense concern and their detection at concentrations well below the threshold necessary to cause health hazards continues to be a challenge with respect to sensitivity, specificity, and selectivity. Ideally, assays for accurate and real time detection of viral agents would not necessitate any pre-processing of the analyte, which would make them applicable for example to bodily fluids (blood, sputum) and man-made as well as naturally occurring bodies of water (pools, rivers). We describe herein a robust biosensor that combines the sensitivity of surface acoustic waves (SAW) generated at a frequency of 325MHz with the specificity provided by antibodies for the detection of viral agents. A lithium tantalate-based SAW transducer with silicon dioxide waveguide sensor platform featuring three test and one reference delay lines was used to adsorb antibodies directed against either Coxsackie virus B4 or the category A bioagent Sin Nombre virus (SNV), a member of the genus Hantavirus, family Bunyaviridae, negative-stranded RNA viruses. Rapid detection (within seconds) of increasing concentrations of viral particles was linear over a range of order of magnitude for both viruses, although the sensor was approximately 5 x 10(5)-fold more sensitive for the detection of SNV. For both pathogens, the sensor's selectivity for its target was not compromised by the presence of confounding Herpes Simplex virus type 1. The biosensor was able to detect SNV at doses lower than the load of virus typically found in a human patient suffering from hantavirus cardiopulmonary syndrome (HCPS). Further, in a proof-of-principle real world application, the SAW biosensor was capable to selectively detect SNV agents in complex solutions, such as naturally occurring bodies of water (river, sewage effluent) without analyte pre-processing. This is the first study that reports on the detection of viral agents using an antibody-based SAW biosensor that has the potential to be used as a hand-held and self-contained device for rapid viral detection in the field.     

Adaptive Remodelling by FliN in the Bacterial Rotary Motor

Sensory adaptation in the Escherichia coli chemosensory pathway has been the subject of interest for decades, with investigation focusing on the receptors that process extracellular inputs. Recent studies demonstrate that the flagellar motors responsible for cell locomotion also play a role, adding or subtracting FliM subunits to maximise sensitivity to pathway signals. It is difficult to reconcile this FliM remodelling with the observation that partner FliN subunits are relatively static fixtures in the motor. By fusing a fluorescent protein internally to FliN, we show that there is in fact significant FliN remodelling. The kinetics and stoichiometry of FliN in steady state and in adapting motors are investigated and found to match the behaviour of FliM in all respects except for timescale where FliN rates are about 4 times slower. We notice that motor adaptation is slower in the presence of the fluorescent protein, indicating a possible source for the difference. The behaviour of FliM and FliN is consistent with a kinetic and stoichiometric model that contradicts the traditional view of a packed, rigid motor architecture.     

Patterns in the benthic communities on the shelf of the sub-Antarctic Prince Edward Islands

Summary Benthic communities at the sub-Antarctic Prince Edward Islands were sampled qualitatively with an epi-benthic sled at 57 stations over a five year period. Additional information on these communities was obtained from replicate underwater photographs. In total, 546 macrofaunal species were found. Despite the extreme isolation and geological youth of the islands, there seems to have been a diverse colonisation. A cluster-analysis based on species abundance aggregated most stations into 8 groups. Each of these groups had a unique depth and substratum combination. Thourella variabilis (Octocoralea), and Cabarea darwinii (Bryozoa) characterised deep rocky assemblages and Serpula vermicularis, Lanice conchilega (Polychaeta) and Magellania kerguelenensis (Brachiopoda) characterised soft substrata. Indicator species separating each of the 8 clusters are given. Trends in percentage cover and densities of major taxa with respect to depth and substratum, as shown by photographs, are described. Deep, rocky substrata were dominated by Porifera, Bryozoa and Cnidaria, while soft-substrata were dominated by Polychaeta, Bivalvia and Brachiopoda. Errant forms consisted predominantly of Echinodermata, with Crustacea being important in shallower habitats. Filter-feeders dominated the benthos of the islands in all habitats.     

Immunolocalisation of aspartic proteinases in the developing human stomach

The distribution and time of appearance in the developing human stomach of the 4 aspartic proteinases, pepsinogen, progastricsin, slow-moving protease and cathepsin D, all present in gastric carcinoma, has been determined by the peroxidase-antiperoxidase method on formalin fixed paraffin embedded sections of fetal stomach. Slow-moving protease appears to be the dominant enzyme from 12 weeks gestation onward, although progastricsin is also present at this time. Pepsinogen and cathepsin D do not appear until 17-18 weeks.     

Mycotic dermatitis in captive carpet snakes (Morelia spilotes variegata)

Geotrichum candidum was isolated from necrotic skin lesions in one of three captive carpet snakes (Morelia spilotes variegata). Hyphae and arthrospores morphologically consistent with this organism were present in histological preparations of lesions from the three snakes.     

Incidence of Uraemia and Requirements for Maintenance Haemodialysis

The biochemistry laboratory records of a 400-bed general hospital serving a population of about 120,000 showed that during the three-year period 1966-8 inclusive 487 patients had at some stage during their admission a blood urea of 100 mg/100 ml or more. Ninety per cent. were aged 50 or over, 79% were 60 or over, and 52% were 70 or over.The case notes of all patients with renal failure admitted during 1966 and 1967 were examined together with those of patients under 60 admitted during 1968. Three observers agreed about the most likely cause of the renal failure in 90% of patients whose case notes were available, or 74% of the total. The raised blood urea was thought to be due to “prerenal” factors in 60% of the patients, to acute tubular necrosis in 80%, to obstructive uropathy in 12%, and to “intrinsic” renal disease in 20%. Renal failure precipitated by such factors as cardiac failure, chest infections, cerebrovascular accidents, and shock was particularly common in old people.The hospital survey and replies to a questionnaire sent to all general practitioners in the area suggest that in the three-year period 14 patients may have been suitable for treatment by maintenance haemodialysis or renal transplantation. This represents a rate of about 39 per million per year under the age of 60 and 28 per million per year under 50.