Responses of the saucer scallop Amusium balloti to potential predators

A high natural mortality rate has been documented for the saucer scallop Amusium balloti, an Australian scallop found on sediment bottoms at 30–60 m deep, but little is known about the causes of mortality. We studied escape responses of A. balloti to five consumers common in the bycatch of the scallop fishery as a means of identifying potential predators. The scallop showed a negligible to weak response when touched with the sea star Pentaceraster regulus and the red portunid crab Portunus rubromarginatus. The response was similar to that observed when the scallop was touched with a plastic object. In contrast, A. balloti showed a consistent and vigorous swimming response to contact with the slipper lobster Thenus orientalis, the blue swimmer crab Portunus pelagicus and the coral crab Charybdis cruciata. This was not a generalized response to crustaceans, given the scallop's weak response to the red portunid crab. This is the first report of a scallop that has a strong swimming escape response to contact with decapod crustacean predators.     

TLR4-initiated and cAMP-mediated abrogation of bacterial invasion of the bladder

The remarkable resistance of the urinary tract to infection has been attributed to its physical properties and the innate immune responses triggered by pattern recognition receptors lining the tract. We report a distinct TLR4 mediated mechanism in bladder epithelial cells (BECs) that abrogates bacterial invasion, a necessary step for successful infection. Compared to controls, uropathogenic type 1 fimbriated Escherichia coli and Klebsiella pneumoniae invaded BECs of TLR4 mutant mice in 10-fold or greater numbers. TLR4 mediated suppression of bacterial invasion was linked to increased intracellular cAMP levels which negatively impacted Rac-1 mediated mobilization of the cytoskeleton. Artificially increasing intracellular cAMP levels in BECs of TLR4 mutant mice restored resistance to type 1 fimbriated bacterial invasion. This finding reveals a novel function for TLR4 and another facet of bladder innate defense.     

Bioenergy production via microbial conversion of residual oil to natural gas

World requirements for fossil energy are expected to grow by more than 50% within the next 25 years, despite advances in alternative technologies. Since conventional production methods retrieve only about one-third of the oil in place, either large new fields or innovative strategies for recovering energy resources from existing fields are needed to meet the burgeoning demand. The anaerobic biodegradation of n-alkanes to methane gas has now been documented in a few studies, and it was speculated that this process might be useful for recovering energy from existing petroleum reservoirs. We found that residual oil entrained in a marginal sandstone reservoir core could be converted to methane, a key component of natural gas, by an oil-degrading methanogenic consortium. Methane production required inoculation, and rates ranged from 0.15 to 0.40 micromol/day/g core (or 11 to 31 micromol/day/g oil), with yields of up to 3 mmol CH(4)/g residual oil. Concomitant alterations in the hydrocarbon profile of the oil-bearing core revealed that alkanes were preferentially metabolized. The consortium was found to produce comparable amounts of methane in the absence or presence of sulfate as an alternate electron acceptor. Cloning and sequencing exercises revealed that the inoculum comprised sulfate-reducing, syntrophic, and fermentative bacteria acting in concert with aceticlastic and hydrogenotrophic methanogens. Collectively, the cells generated methane from a variety of petroliferous rocks. Such microbe-based methane production holds promise for producing a clean-burning and efficient form of energy from underutilized hydrocarbon-bearing resources.     

Purification and characterization of subcomponent C1q of the first component of bovine complement

Bovine C1q, a subcomponent of the first component of complement, was purified in high yield by a combination of euglobulin precipitation, and ion-exchange and molecularsieve chromatography on CM-cellulose and Ultrogel AcA 34. Approx. 12-16mg can be isolated from 1 litre of serum, representing a yield of 13-18%. The molecular weight of undissociated subcomponent C1q, as determined by equilibrium sedimentation, is 430000. On sodium dodecyl sulphate/polyacrylamide gels under non-reducing conditions, subcomponent C1q was shown to consist of two subunits of mol.wts. 69000 and 62000 in a molar ratio of 2:1. On reduction, the 69000-mol.wt. subunit gave chains of mol.wts. 30000 and 25000 in equimolar ratio, and the 62000-mol.wt. subunit decreased to 25000. The amino acid composition, with a high value for glycine, and the presence of hydroxyproline and hydroxylysine, suggests that there is a region of collagen-like sequence in the molecule. This is supported by the loss of haemolytic activity and the degradation of the polypeptide chains of subcomponent C1q when digested by collagenase. All of these molecular characteristics support the structure of six subunits, each containing three different polypeptide chains, with globular heads connected by collagen triple helices as proposed by Reid & Porter (1976) (Biochem. J.155, 19-23) for human subcomponent C1q. Subcomponent C1q contains approx. 9% carbohydrate; analysis of the degree of substitution of the hydroxylysine residues revealed that 91% are modified by the addition of the disaccharide unit Gal-Glc. Bovine subcomponent C1q generates full C1 haemolytic activity when assayed with human subcomponents C1r and C1s.     

Response of lake phytoplankton communities to in situ manipulations of light intensity and colour

Phytoplankton preferences for light intensity and colour weredetermined in field experiments using coloured plexiglass cubessuspended at different depths in Heney Lake, Québec.Diatoms and green algae favoured intensities greater than 1%I_o (surface irradiance) contrary to dinoflagellates and otherflagellates that preferred lower intensity. Red radiation usuallyincreased the relative proportion of blue-greens, diatoms andgreen algae, whereas it reduced that of dinoflageilates. Wepropose that differential utilization of the light gradientallows certain phytoplankton taxa to partition the water column,thereby reducing potential competition. This is supported bythe general agreement between our findings and the known depthdistribution of algae in lakes.     

Patterns and drivers of Araucaria araucana forest growth along a biophysical gradient in the northern Patagonian Andes: Linking tree rings with satellite observations of soil moisture

Araucaria araucana (Araucaria) is a long‐lived conifer growing along a sharp west–east biophysical gradient in the Patagonian Andes. The patterns and climate drivers of Araucaria growth have typically been documented on the driest part of the gradient relying on correlations with meteorological records, but the lack of in situ soil moisture observations has precluded an assessment of the growth responses to soil moisture variability. Here, we use a network of 21 tree‐ring width chronologies to investigate the spatiotemporal patterns of tree growth through the entire gradient and evaluate their linkages with regional climate and satellite‐observed surface soil moisture variability. We found that temporal variations in tree growth are remarkably similar throughout the gradient and largely driven by soil moisture variability. The regional spatiotemporal pattern of tree growth was positively correlated with precipitation (r = 0.35 for January 1920–1974; P < 0.01) and predominantly negatively correlated with temperature (r = ?0.38 for January–March 1920–1974; P < 0.01) during the previous growing season. These correlations suggest a temporally lagged growth response to summer moisture that could be associated with known physiological carry‐over processes in conifers and to a response to moisture variability at deeper layers of the rooting zone. Notably, satellite observations revealed a previously unobserved response of Araucaria growth to summer surface soil moisture during the current rather than the previous growing season (r = 0.65 for 1979–2000; P < 0.05). This new response has a large spatial footprint across the mid‐latitudes of the South American continent (35°–45°S) and highlights the potential of Araucaria tree rings for palaeoclimatic applications. The strong moisture constraint on tree growth revealed by satellite observations suggests that projected summer drying during the coming decades may result in regional growth declines in Araucaria forests and other water‐limited ecosystems in the Patagonian Andes.     

Parallel tandem: a program for parallel processing of tandem mass spectra using PVM or MPI and X!Tandem

A method for the rapid correlation of tandem mass spectra to a list of protein sequences in a database has been developed. The combination of the fast and accurate computational search algorithm, X!Tandem, and a Linux cluster parallel computing environment with PVM or MPI, significantly reduces the time required to perform the correlation of tandem mass spectra to protein sequences in a database. A file of tandem mass spectra is divided into a specified number of files, each containing an equal number of the spectra from the larger file. These files are then searched in parallel against a protein sequence database. The results of each parallel output file are collated into one file for viewing through a web interface. Thousands of spectra can be searched in an accurate, practical, and time effective manner. The source code for running Parallel Tandem utilizing either PVM or MPI on Linux operating system is available from http://www.thegpm.org. This source code is made available under Artistic License from the authors.     

Prevention of meningo/encephalomyelitis due to Sarcocystis neurona infection in mice is mediated by CD8 cells

Immunodeficient CD8 knockout mice were infected with Sarcocystis neurona merozoites, in order to determine the role of CD8 cells in protective immunity. Using a direct agglutination test, all infected mice seroconverted by selected time points. Infected mice developed splenomegaly and bilateral lymphadenopathy. Histological changes included marked follicular development in the spleen, endothelitis and moderate perivascular inflammation in the liver, and meningoencephalitis in the brain. Infected brains were positive for S. neurona by polymerase chain reaction. Corresponding to histopathological changes, there were decreased numbers of B-cells in the spleen. The mice did not have significant memory (CD44hi/CD4) or effector (CD45RBhi/CD4) populations present at the time of euthanasia. Flow cytometry confirmed the lack of CD8 cells. Taken together, these data support previous studies suggesting a critical role for CD8 cells in the prevention of menigoencephalitis in S. neurona-infected mice.     

Characterization of moorland vegetation and the prediction of bird abundance using remote sensing

Aims To characterize and identify upland vegetation composition and height from a satellite image, and assess whether the resulting vegetation maps are accurate enough for predictions of bird abundance. Location South‐east Scotland, UK. Methods Fine‐taxa vegetation data collected using point samples were used for a supervised classification of a Landsat 7 image, while linear regression was used to model vegetation height over the same image. Generalized linear models describing bird abundance were developed using field‐collected bird and vegetation data. The satellite‐derived vegetation data were substituted into these models and efficacy was examined. Results The accuracy of the classification was tested over both the training and a set of test plots, and showed that more common vegetation types could be predicted accurately. Attempts to estimate the heights of both dwarf shrub and graminoid vegetation from satellite data produced significant, but weak, correlations between observed and predicted height. When these outputs were used in bird abundance–habitat models, bird abundance predicted using satellite‐derived vegetation data was very similar to that obtained when the field‐collected data were used for one bird species, but poor estimates of vegetation height produced from the satellite data resulted in a poor abundance prediction for another. Conclusions This pilot study suggests that it is possible to identify moorland vegetation to a fine‐taxa level using point samples, and that it may be possible to derive information on vegetation height, although more appropriate field‐collected data are needed to examine this further. While remote sensing may have limitations compared with relatively fine‐scale fieldwork, when used at relatively large scales and in conjunction with robust bird abundance–habitat association models, it may facilitate the mapping of moorland bird abundance across large areas.