Sex pheromone biology and behavior of the cowpea weevilCallosobruchus maculatus (Coleoptera: Bruchidae)

Female cowpea weevils,Callosobruchus maculatus (F.), emitted a pheromone which excited males. Pheromone release began soon after emergence and continued for one week. Synchronization of pheromone release with calling behavior was demonstrated. Mating reduced pheromone release but not male response. Pheromone obtained by aeration collection was utilized for determining a quantitative dose-response relationship.Mention of a commercial product does not constitute an endorsement by the USDA.Visiting scholar on leave from Shanghai Institute of Entomology, PRC.     

Structural analysis of substrate binding by the molecular chaperone DnaK

DnaK and other members of the 70-kilodalton heat-shock protein (hsp70) family promote protein folding, interaction, and translocation, both constitutively and in response to stress, by binding to unfolded polypeptide segments. These proteins have two functional units: a substrate-binding portion binds the polypeptide, and an adenosine triphosphatase portion facilitates substrate exchange. The crystal structure of a peptide complex with the substrate-binding unit of DnaK has now been determined at 2.0 angstroms resolution. The structure consists of a beta-sandwich subdomain followed by alpha-helical segments. The peptide is bound to DnaK in an extended conformation through a channel defined by loops from the beta sandwich. An alpha-helical domain stabilizes the complex, but does not contact the peptide directly. This domain is rotated in the molecules of a second crystal lattice, which suggests a model of conformation-dependent substrate binding that features a latch mechanism for maintaining long lifetime complexes.     

Interaction of the Hsp70 molecular chaperone, DnaK, with its cochaperone DnaJ

Chaperones of the Hsp70 family bind to unfolded or partially folded polypeptides to facilitate many cellular processes. ATP hydrolysis and substrate binding, the two key molecular activities of this chaperone, are modulated by the cochaperone DnaJ. By using both genetic and biochemical approaches, we provide evidence that DnaJ binds to at least two sites on the Escherichia coli Hsp70 family member DnaK: under the ATPase domain in a cleft between its two subdomains and at or near the pocket of substrate binding. The lower cleft of the ATPase domain is defined as a binding pocket for the J-domain because (i) a DnaK mutation located in this cleft (R167H) is an allele-specific suppressor of the binding defect of the DnaJ mutation, D35N and (ii) alanine substitution of two residues close to R167 in the crystal structure, N170A and T173A, significantly decrease DnaJ binding. A second binding determinant is likely to be in the substrate-binding domain because some DnaK mutations in the vicinity of the substrate-binding pocket are defective in either the affinity (G400D, G539D) or rate (D526N) of both peptide and DnaJ binding to DnaK. Binding of DnaJ may propagate conformational changes to the nearby ATPase catalytic center and substrate-binding sites as well as facilitate communication between these two domains to alter the molecular properties of Hsp70.     

Initial stability of a modular uncemented, porous-coated femoral stem: a mechanical study

A versatile modular hip system was used to evaluate the initial stability of a cementless femoral stem in anatomically consistent composite bones. Four implant bone configurations of varying proximal and distal fit/fill were tested. The implanted femurs were tested on an Instron 1331 materials testing machine in neutral loading and flexion loading; both translational micromotions and rotations of the implant relative to the bone were recorded on all three axes of motion, accounting for all 6 degrees of freedom of joint motion. Implants were then sectioned, and both endosteal canal fit and intramedullary canal fill were measured. Results indicate that (1) loading the implant in flexion by out-of-plane forces significantly increases both relative translation and rotation at the interface, (2) increasing the proximal fit reduces implant rotation about its longitudinal axis in flexion loading and (3) increasing the distal canal fit and fill increases prosthesis rotation about its longitudinal axis in flexion loading. These results indicate that the femoral stem is more unstable in out-of-plane loading, such as during stair climbing, and that increasing the proximal fit may enhance the initial rotational stability of an uncemented femoral stem.     

An iterative physical optics approach for analyzing theelectromagnetic scattering by large open-ended cavities

A formulation based on the high frequency asymptotic principles of physical optics is developed for analyzing the scattering by relatively arbitrary open-ended waveguide cavities containing complex interior terminations. A magnetic field integral equation (MFIE) is obtained for the equivalent currents on the interior cavity walls and is solved using an iterative physical optics (IPO) algorithm which iteratively applies physical optics to account for multiple reflections inside the cavity. The number of iterations required for convergence is related to the expected number of important reflections. The IPO method is more approximate than a matrix solution of the MFIE, but it is quite accurate for electrically large cavities and is much more efficient. Numerical results are presented which demonstrate the convergence and accuracy of the method by comparison with modal reference solutions     

Mattesia trogodermae infection rates as influenced by mode of transmission, dosage and host species

Specificity of infection by Mattesia trogodermae Canning was tested on six species of Trogoderma. Exposure of insects to similar numbers of spores indicated infections are always fatal in T. sternale Jayne, T. simplex Jayne, T. glabrum (Herbst) and T. inclusum LeConte. Rates of mortality (LT₅₀'s) were similar among the susceptible species and infection always reached 100 per cent in exposed insects. Trogoderma grassmani Beal and T. variabile Ballion were not infected at the dosages studied.

When eggs were seeded on to medium containing spores, the number of adults produced from such cultures was reduced by 50 per cent with an inoculation rate of 50 spores/g medium. Five thousand spores/g were necessary to infect all larvae before reaching the adult stage, however, this effect could be achieved with fewer total spores per jar if they were concentrated in the upper 1/5 of medium in the culture container. Infected larvar, when introduced into cultures, also cause infection of newly hatched larvae and subsequent reduction of adult production. A single infected larva reduced adult production by 25 per cent; 100 per cent infection of larvae was effected with 25–50 infected larvae per 50 g medium.

Adult T. glabrum males externally contaminated with Mattesia were able to transmit infective spores to females. Spore presence on the adults was determined by feeding the freeze-killed insects to larvae and inspecting the larvae for infection several weeks later. Male beetles were initially contaminated by being drawn to a corrugated cardboard inoculation device treated with pheromone ((Z)-14-methyl-8-hexadecen-1-ol) and dusted with Mattesia powder. Pheromone-baited inoculation devices resulted in contamination of 96 per cent of test insects placed in the arena whereas only 56 per cent picked up spores from inoculation devices containing only Mattesia spores (no pheromone).     

Analysis of EM penetration into and scattering by electricallylarge open waveguide cavities using Gaussian beam shooting

Gaussian beam (GB) representation methods are used to analyze the electromagnetic coupling into and the scattering by a large nonuniform cavity. The aperture field in the cavity is decomposed into beams using the Gabor expansion, and shooting techniques are then employed. The method is illustrated only for the two-dimensional (2-D) case. The GBs are tracked axially using the rules of beam optics which ignore any beam distortion upon reflection at the walls. The effects of beam distortion are not significant for relatively slowly varying waveguide cavities. The field scattered into the exterior by the termination within the cavity is found using a reciprocity integral formulation which requires a knowledge of the beam fields near the termination. Numerical results based on this GB approach are presented and compared with results based on an independent reference solution     

Association of crescentic glomerulonephritis with membranous glomerulonephropathy: a report of three cases

Association of membranous glomerulonephropathy with crescentic glomerulonephritis is apparently extremely rare. We report three patients who had this combination. One patient had biopsy-proven membranous glomerulonephropathy thirteen months prior to sudden and rapid decline in renal function necessitating hemodialysis. A repeat renal biopsy showed a superimposed crescentic nephritis and antiglomerular (GBM) antibodies were demonstrable in the serum. A second patient had proteinuria of unknown duration and then developed renal failure. Renal biopsy showed crescentic nephritis with a fine granular glomerular immunofluorescence for IgG typical of membranous glomerulonephropathy. Anti-GBM antibodies were present in this patient's serum. The third patient presented with acute renal failure of moderate severity. A renal biopsy revealed crescentic nephritis, granular deposits of immunoglobulins, and epimembranous electron-dense deposits typical of membranous glomerulonephropathy. Although his creatinine clearance improved spontaneously, nephrotic syndrome has persisted and a repeat renal biopsy showed a progression of the membranous glomerulonephropathy with the disappearance of the crescentic lesions. The reason for this peculiar association of membranous glomerulonephropathy and crescentic glomerulonephritis is unclear. It is possible that deposition of immune-complexes along glomerular basement membrane may render the glomerulus more susceptible to additional injury from a variety of other agents. Alternatively, depostis formed in one disease could initiate release of normal or altered basement membrane material and lead to formation of anti-GBM antibodies and subsequent development.     

Behavior of the lesser grain borerRhyzopertha dominica (Coleoptera: Bostrichidae)

Adult males of the lesser grain borer,Rhyzopertha dominica (F.), produce a pheromone that attracts both sexes. The volatiles from males collected on filter paper or Porapak-Q were attractive in two laboratory bioassays. The mating behavior is described and the function of the phen infested with the borer.Mention of a commercial product does not constitute an endorsement by the USDA.     

Interspecific response to sex pheromones,and calling behavior of severalAttagenus species (Coleoptera: Dermestidae)

Females of severalAttagenus species demonstrated calling behaviors similar to those previously reported forA. elongatulus. Attagenus rufipennis females did not call until they were 12–14 days old. OtherAttagenus species called at approx. 4 days of age. All species exhibited diurnal periods of calling activity. Interspecific pheromone responses were tested, withA. megatoma megatoma, A. megatoma canadensis, A. megatoma japonicus, andA. schaefferi spurcus showing equal cross-responses. Male response to females was demonstrated inA. rufipennis andA. bicolor. Attagenus rufipennis, bicolor, andelongatulus males responded only to female extracts of their own species.Mention of a proprietary product does not constitute an endorsement by the USDA.