Radiation-force assisted targeting facilitates ultrasonic molecular imaging

Ultrasonic molecular imaging employs contrast agents, such as microbubbles, nanoparticles, or liposomes, coated with ligands specific for receptors expressed on cells at sites of angiogenesis, inflammation, or thrombus. Concentration of these highly echogenic contrast agents at a target site enhances the ultrasound signal received from that site, promoting ultrasonic detection and analysis of disease states. In this article, we show that acoustic radiation force can be used to displace targeted contrast agents to a vessel wall, greatly increasing the number of agents binding to available surface receptors. We provide a theoretical evaluation of the magnitude of acoustic radiation force and show that it is possible to displace micron-sized agents physiologically relevant distances. Following this, we show in a series of experiments that acoustic radiation force can enhance the binding of targeted agents: The number of biotinylated microbubbles adherent to a synthetic vessel coated with avidin increases as much as 20-fold when acoustic radiation force is applied; the adhesion of contrast agents targeted to alpha(v)beta3 expressed on human umbilical vein endothelial cells increases 27-fold within a mimetic vessel when radiation force is applied; and finally, the image signal-to-noise ratio in a phantom vessel increases up to 25 dB using a combination of radiation force and a targeted contrast agent, over use of a targeted contrast agent alone.     

Life table for Leptoglossus occidentalis Heidemann (Heteroptera: Coreidae) and prediction of damage in lodgepole pine seed orchards

Abstract 1 Fecundity, egg hatch and nymphal survivorship of Leptoglossus occidentalis Heidemann were determined and used to develop a damage prediction formula for seed bugs in lodgepole pine seed orchards. 2 A single overwintered L. occidentalis female may lay up to 80 eggs during early and mid‐season cone development. 3 Up to 83.4% of eggs that were attached to branches with tape hatched successfully, compared with 53.5% of eggs attached to needles with wire. Egg parasitism was only observed in egg masses attached with wire. 4 Egg masses attached with wire suffered approximately 30% mortality from parasitism, primarily by Gryon pennsylvanicum (Ashmead). 5 Approximately 15.1 and 2.5% of first instars survived to adulthood in 2000 and 2001, respectively. Survival of caged nymphs that were protected from predators was 14.5 and 17.8%, respectively. 6 A composite survival table indicated that 9.3% of eggs laid by L. occidentalis are expected to survive to adulthood. 7 Based on previously determined damage estimates for each life stage of feeding during three periods of cone development, a hypothetical density of one seed bug per tree early in the season will result in an expected seed loss of approximately 310 seeds.     

Sulcatol: population aggregation pheromone in the scolytid beetle, Gnathotrichus sulcatus

The population aggregation pheromone produced by males of Gnathotrichus sulcatus, a timber pest, has been identified from boring dust as a $\text{65}\text{35}$ mixture of the (S)-(+) and the (R)-(?) enantiomers of 6-methyl-5-hepten-2-ol. In field studies beetles were attracted in a 2·65 female: 1 male ratio by racemic synthetic pheromone.     

The Inheritance of Enzyme Variants for Tyrosine Aminotransferase, Nadp-Dependent Malate Dehydrogenase, Nadp-Dependent Isocitrate Dehydrogenase, and Tetrazolium Oxidase in TETRAHYMENA PYRIFORMIS, Syngen 1

The isozymic patterns of tyrosine aminotransferase, NADP malate dehydrogenase, NADP isocitrate dehydrogenase, and tetrazolium oxidase were examined by starch-gel electrophoresis in Tetrahymena pyriformis, syngen 1. The genetics of the alleles controlling these enzymes was studied through a breeding program. Each enzyme locus was shown to assort vegetatively, as do other loci in this organism. A detailed analysis of the assortment process for the tyrosine aminotransferase locus indicated that the rate of stabilization of heterozygotes into pure types was essentially identical to previously-reported rates for other loci.     

Close-range, in-flight integration of olfactory and visual information by a host-seeking bark beetle

A long‐standing controversy questions whether foraging bark beetles assess the suitability of individual host trees using cues at close range while flying or engage in random landing followed by contact assessment. In most cases, visual discrimination mechanisms are ignored. We show that pheromone‐responding mountain pine beetles (MPB), Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae), can visually discriminate between ‘host’ (black) and ‘non‐host’ (white) traps arranged in small clusters, in the absence of additional host olfactory information, and that males (but not females) demonstrate a greater preference for combined host visual and olfactory cues. However, white, non‐host traps baited with a host volatile were as attractive as unbaited, black host traps. Our results support the hypotheses that when deciding to land, the MPBs integrate visual and olfactory information and can process cues in both sensory modes at relatively close range (≤2 m). Thus, host selection mechanisms in this species are unlikely to be random with respect to either sensory mode.     

Atmospheric microbiology in the northern Caribbean during African dust events

Between July 2000 and August 2001 forty-threeair samples were collected in the northernCaribbean: Twenty-six in the US VirginIslands, and 17 samples aboard ship during two1-week cruises. Samples were collected duringAfrican dust events and non-dust conditions andscreened for the presence of culturablebacteria and fungi. A total of 3,652 liters ofair were collected during non-dust conditions,with 19 bacteria and 28 fungi being recovered.During dust conditions a total of 2,369 litersof air were screened resulting in the recoveryof 171 bacteria and 76 fungi. A statisticallysignificant difference was found between thetwo data sets. These results support previousAfrican dust research and further demonstratethat dust particles can serve as a vessel forthe global dispersion of bacteria and fungi.Dustborne microorganisms may play a significantrole in the ecology and health of downwindecosystems.     

Inter‐kingdom signaling — symbiotic yeasts produce semiochemicals that attract their yellowjacket hosts

In recent studies, the yeast species Hanseniaspora uvarum and Lachancea thermotolerans were isolated from the digestive tract of four North American yellowjacket species (Hymenoptera: Vespidae), and attraction of yellowjackets to brewer's yeast, Saccharomyces cerevisiae (all Saccharomycetaceae), growing on fruit powder was demonstrated. We tested the hypothesis that Vespula spp. are attracted to cultures of H. uvarum and L. thermotolerans and their respective volatiles. In field experiments, we found that H. uvarum and L. thermotolerans are attractive to three species of yellowjacket, but only when grown on grape juice‐infused yeast peptone dextrose (YPD) agar. Using gas chromatography‐mass spectrometry, we analyzed the headspace volatiles produced by these yeasts, and field tested an 18‐component yeast synthetic semiochemical blend. This synthetic blend attracted western yellowjackets, Vespula pensylvanica (Saussure), but no other yellowjacket species. Acetic acid or ethanol added to the synthetic blend at biologically relevant doses either had no effect or significantly lowered trap captures. Our results demonstrate that yeast symbionts isolated from the digestive tract of yellowjackets are attractive to their hosts. Further research is needed to identify the volatiles mediating attraction of species other than V. pensylvanica to the yeast cultures.     

Enhanced nitrogen mineralization in mowed or glyphosate treated cover crops compared to direct incorporation

Information on how management by mowing and herbicide alter residue quality and nitrogen (N) inputs would be valuable to improve prediction of N availability. Mowing and glyphosate application are widely used by growers to limit cover crop growth and facilitate incorporation. A mixture of cover crops, hairy vetch (Vicia villosa L.), oriental mustard (Brassica junceaL.) and cereal rye (Secale cerealeL.), was investigated as a means to improve soil quality and optimize N availability. There is limited information on how mowing or glyphosate application influence cover crop decomposition and N mineralization from these heterogeneous residues. A rye cover crop was grown in the field over the winter and transferred to containers as an intact soil profile to conduct a greenhouse study. Management treatments (mowing and glyphosate) were imposed eight days before incorporation. Plant and soil N dynamics were monitored. The experiment was repeated with the addition of a tri-mixture cover crop. Inorganic NO₃^– in bare soil ranged from 6 to 10 g N g soil^–1 over 39 days. Similar or lower levels of soil NO₃^– were observed after rye residue incorporation, from 2 to 6 g N g^–1; consistent with N-immobilization. Application of untreated, mixed cover crop residues generally was associated with higher levels of soil inorganic NO₃^–, from 3 to 11 g N g^–1. For both rye and mixed residues, management by mowing or glyphosate enhanced N mineralization by 10 to 100%, compared to untreated residues. At the same time, application of mowing or glyphosate 8 days before cover crop incorporation seemed to reduce the amount of residues by about half compared to untreated controls. Belowground biomass was reduced more than aboveground, although recovery of senescent roots may have been incomplete. Management by glyphosate or mowing enhanced soil inorganic N availability in the short-term while simultaneously reducing carbon and N inputs.