Spatio-temporal dynamics of willow beetle (Phratora vulgatissima) in short-rotation coppice willows grown as monocultures or a genetically diverse mixture

1 Phratora vulgatissima (Chrysomelidae) is the major pest of short-rotation coppice willows in the U.K., capable of causing severe defoliation in monoculture plantations. As this beetle shows feeding preferences between willow clones, knowledge of the spatio-temporal dynamics of P. vulgatissima is needed in order to assess the effects of mixed clonal plantings on the management of this pest. 2 Distribution patterns of adult P. vulgatissima were monitored over a season at a spatial scale of every tree or every other tree in single clone plantings (monocultures) of three willow clones and in a regular row mixture of these clones. 3 Distribution indices (deviation from Complete Spatial Randomness) demonstrated that P. vulgatissima adults were spatially aggregated on favourable clones in the monocultures and the mixture. The degree of aggregation (measured by the k-parameter of the negative binomial) differed between willow clones. Beetles were highly aggregated at the start of the season, but less so later. 4 Dispersal studies of P. vulgatissima adults over time showed a pattern of beetle infestation along rows of the preferred clones in a regularly structured mixture. In the monocultures, movement was less directional. 5 Plantation design offers some potential for more effective non-chemical pest management for P. vulgatissima. Monitoring of the pest must take account of our findings that adults occur in mobile aggregations.     

Consequences of Piñon-Juniper Woodland Fuel Reduction: Prescribed Fire Increases Soil Erosion While Mastication Does Not

Ecosystems - Fire suppression has increased fuel load and the risk of catastrophic wildfire in forest and woodland ecosystems across the Western United States. In an effort to reduce fuel load and...     

Effects of dnats genes on the replication of plasmids in Bacillus subtilis

An essential region (2.3 kb) for the replication of a low-copy-number plasmid, pBS-2, has been identified and cloned into plasmid pHV60 in Bacillus subtilis. The resultant plasmid, pKW1, and two other plasmids, pC194 (medium copy number) and pTP5 (high copy number), were examined by double radio-labelling and gel electrophoresis to determine which host functions are required for their replication in B. subtilis. Replication of pKW1 requires the functions of most dna genes, in particular dnaB, C, E, F, G and H; pC194 requires only dnaG and H; and pTP5 requires dnaE, F, G and H. Thus dnaG and dnaH are required for the replication of all three plasmids tested, even though each plasmid showed a different spectrum of dependency on other host functions. Because of its greater dependence on host functions and its low copy number, pKW1 should be a useful model with which to investigate the function of host genes in the replication of DNA in B. subtilis. pKW1 should also be a useful shuttle vector for cloning of genes in B. subtilis in cases when high gene dosage might be a problem.     

HGF/SF Induces Mesothelial Cell Migration and Proliferation by Autocrine and Paracrine Pathways

Mesothelial repair differs from that of other epithelial-like surfaces as healing does not occur solely by centripetal in-growth of cells as a sheet from the wound margins. Mesothelial cells lose their cell-cell junctions, divide, and adopt a fibroblast-like morphology while scattering across and covering the wound surface. These features are consistent with a cellular response to hepatocyte growth factor/scatter factor (HGF/SF). In this study, we examined the ability of mesothelial cells to secrete HGF/SF and investigated its possible role as an autocrine regulator of mesothelial cell motility and proliferation. We found that human primary mesothelial cells expressed HGF/SF mRNA and secreted active HGF/SF into conditioned medium as determined by ELISA and in a scattering bioassay. These cells also expressed the HGF/SF receptor, Met, as shown by RT-PCR and by Western blot analysis and immunofluorescence. Incubation of mesothelial cells with neutralizing antibodies to HGF/SF decreased cell migration to 25% of controls, whereas addition of HGF/SF disrupted cell-cell junctions and induced scattering and enhanced mesothelial cell migration. Furthermore, HGF/SF showed a small but significant mitogenic effect on all mesothelial cell lines examined. In conclusion, HGF/SF is produced by mesothelial cells and induces both motility and proliferation of these cells. These data are consistent with HGF/SF playing an autocrine role in mesothelial healing.     

Energy-dependent formation of free ATP in yeast submitochondrial particles, and its stimulation by oligomycin

Yeast submitochondrial particles, in a P_i- and NADH-dependent reaction, produced low concentrations of free ATP in the absence of added ADP. This formation of free ATP, as measured by the luciferin-luciferase method, was strongly stimulated by oligomycin. For maximal stimulation, oligomycin was to be added not earlier than 5–10 min after the addition of NADH. Upon addition of antimycin or FCCP the system was completely inhibited. The amount of free ATP formed corresponded to one-third of the amount of bound ATP in submitochondrial particles. The stimulatory effect of oligomycin disappeared if the submitochondrial particles were spun down after oligomycin stimulation and then resuspended in the reaction medium, whereas submitochondrial particles with no oligomycin added initially were stimulated by oligomycin after the same procedure. A different picture emerged with addition of ADP. If the submitochondrial particles were preenergized with NADH in the presence of oligomycin before the addition of ADP the formation of free ATP upon subsequent addition of ADP was inhibited by oligomycin. In the presence of oligomycin, but lacking preenergization with NADH, a stimulation of free ATP formation was achieved with added ADP. A possible explanation for the stimulating effect of oligomycin on ATP formation in the absence of added ADP is that it enhances the release of bound ATP in an energy-requiring process. The release of only about one-third of the bound ATP could indicate that one of three nucleotide-binding subunits involved in the mechanism of ATP formation by ATP synthase is in a state suitable for such an energy-dependent release of ATP.