Effect of light energy on alkali-released virions from Anagrapha falcifera nucleopolyhedrovirus

We compared the insecticidal activities of occluded and nonoccluded AfMNPV baculovirus obtained by dissolving the occlusion bodies (OB) with sodium carbonate. Droplet feeding and cotton leaf feeding bioassay techniques were used to determine the dose response against neonate Trichoplusia ni (Hübner) and loss of insecticidal activity when the virus was exposed to simulated sunlight from a xenon light source. Using droplet bioassays to determine a dose response, nonoccluded virus (NOV) was 20 times more active (LC(50) = 4.8 x 10(3) OB/ml, dissolved) than occluded virus (LC(50) = 9.6 x 10(4) OB/ml) when the samples remained wet. However, NOV lost activity when air dried before being tested by droplet (LC(50) > 1.0 x 10(6) OB/ml) or leaf feeding (LC(50) > 3.0 x 10(6) OB/ml) bioassays. Adding sucrose to NOV prevented the loss of insecticidal activity when samples were dried. The activity of NOV with 2% sucrose was similar to that of occluded virus samples, with or without sucrose, in both droplet feeding and leaf feeding assays. These results indicate that the OB protected the insecticidal activity of virions from the detrimental effects of drying. The OB also provided some protection from the detrimental effects of simulated sunlight (xenon) exposure. NOV samples exposed to xenon light had significantly greater loss of insecticidal activity than did similar samples of occluded virus. Without advancement in technologies, such as formulations, possible benefits of increased insecticidal activity from the use of nonoccluded virus is probably not sufficient to offset the rapid loss of activity due to drying or light exposure.     

Adsorption of thermomonospora fusca E(5) cellulase on silanized silica

The adsorption kinetics and dodeceyltrimethylammonium-bromide-mediated elution of Thermomonospora fusca E(5) cellulase were recorded in situ, at hydrophobic, silanized silica. Experiments were performed at different solution concentrations, ranging from 0.001 to 0.70 mg/mL. Plateau values of adsorbed mass generally increased with increasing solution concentration, with the adsorbed layer being only partially eluted by buffer. Treatment with surfactant removed more of the adsorbed enzyme in each case, with the remaining adsorbed mass varying little among experiments. Adsorption of E(5) into this nonremovable state was suggested to occur early in the adsorption process and continue until some critical surface concentration was reached. Beyond this critical value of adsorbed mass, adsorption progressed with the protein adopting more loosely bound states. Adsorption kinetic data were interpreted with reference to an adsorption mechanism allowing for irreversible adsorption into two dissimilar states. These states were distinguished by differences in occupied interfacial area, and binding strength, presumably a result of differences in structure. Comparison of the data to the kinetic model based on this mechanism showed that the fraction of adsorbed molecules present in the more tightly bound state decreased as adsorption occurred from solutions of increasing concentration. However, the absolute values of more tightly bound molecules were less dependent on adsorption conditions.     

TOPAL 2.0: improved detection of mosaic sequences within multiple alignments

MOTIVATION: The Dss statistic was proposed by McGuire et al. (Mol. Biol. Evol., 14, 1125-1131, 1997) for scanning data sets for the presence of recombination, an important step in some phylogenetic analyses. The statistic, however, could not distinguish well between among-site rate variation and recombination, and had no statistical test for significant values. This paper addresses these shortfalls. RESULTS: A modification to the Dss statistic is proposed which accounts for rate variation to a large extent. A statistical test, based on parametric bootstrapping, is also suggested. AVAILABILITY: The TOPAL package (version 2) may be accessed from http:/ /www.bioss.sari.ac.uk/frank/Genetics and by anonymous ftp from typ://ftp.bioss.sari.ac.uk in the directory pub/phylogeny/topal. CONTACT: frank@bioss.sari.ac.uk     

Effectiveness of thiamethoxam-coated spheres against blueberry maggot flies (Diptera: Tephritidae)

Studies were conducted to evaluate the mortality of blueberry maggot, Rhagoletis mendax Curran, flies exposed to thiamethoxam- and imidacloprid-coated biodegradable (8-cm-diameter) red spheres, under both laboratory and field conditions. Laboratory studies with spheres coated with 0.1-2.0% (AI) of thiamethoxam indicated that they are effective against R. mendax; however, no dose-dependent response was observed. Studies on the effect of visitation time on thiamethoxam-coated spheres showed a decrease in R. mendax mortality as the duration of visitation time decreased from 60 to 10 s. Under field conditions, significantly more flies were captured on Plexiglas panes below the 2% (AI) thiamethoxam-coated spheres when compared with similar panes below untreated spheres. In field evaluations of thiamethoxam- and imidacloprid-coated spheres, imidacloprid-coated spheres (2.0% [AI]) were found to be significantly more effective than thiamethoxam-coated spheres (0.5-4.0% [AI]). Field trials to characterize the levels of mortality associated with aging pesticide-coated spheres revealed that the effectiveness of treated spheres decreased with increasing age of sphere, and this reduction in effectiveness is greater in thiamethoxam-coated spheres than in imidacloprid-coated spheres. These results provide comparative data on the effectiveness of thiamethoxam- and imidacloprid-coated spheres and support the potential of using pesticide-treated spheres for control of blueberry maggot flies.     

Hot water treatment and insecticidal coatings for disinfesting limes of mealybugs (Homoptera: Pseudococcidae)

Hot water immersion and insecticidal coatings were tested to determine if they could be used to disinfest Persian limes, Citrus latifolia Tanaka, of the mealybug pests Planococcus citri Risso and Pseudococcus odermatti Miller & Williams. A 20-min 49 degrees C hot water immersion treatment is effective in killing mealybugs and all other arthropods tested found externally on limes, or under the calyx. No insects or mites were found to survive after the 20-min hot water treatment. In this test, 7,200 limes were treated with 1,308 insects killed and zero survivors. Treatment at 49 degrees C for 20 min did not significantly affect quality when treated fruit were compared with untreated control fruit. Four coatings were tested at a 3% rate: two petroleum-based oils (Ampol and Sunspray oil), a vegetable oil (natural oil), and a soap (Mpede). The coatings gave up to 94% kill (Ampol) of mealybugs, which is not sufficient to provide quarantine security. The coatings might be effective as a postharvest dip before shipment.     

Sunlight persistence and rainfastness of spray-dried formulations of baculovirus isolated from Anagrapha falcifera (Lepidoptera: Noctuidae)

Nuclear polyhedrosis viruses such as the one isolated from the celery looper, Anagrapha falcifera (Kirby) (AfMNPV), have the potential to be successful bioinsecticides if improved formulations can prevent rapid loss of insecticidal activity from environmental conditions such as sunlight and rainfall. We tested 16 spray-dried formulations of AfMNPV to determine the effect of different ingredients (e.g., lignin, corn flour, and so on) on insecticidal activity after simulated rain and simulated sunlight (at Peoria, IL) and natural sunlight exposures (at Tifton, GA). The most effective formulation contained pregelatinized corn flour and potassium lignate, which retained more than half of its original activity after 5 cm of simulated rain, and almost full activity after 8 h of simulated sunlight. In Georgia, formulations made with and without lignin were compared for persistence of insecticidal activity when exposed to natural sunlight. In addition, the effect of fluorescent brighteners as formulation components and spray tank additives was tested. Results showed that the formulations with lignin had more insecticidal activity remaining after sunlight exposure than formulations without lignin. The inclusion of brighteners in the formulation did not improve initial activity or virus persistence. However, a 1% tank mix significantly enhanced activity and improved persistence. Scanning electron micrographs revealed discreet particles, and transmission electron micrographs showed virus embedded within microgranules. Results demonstrated that formulations made with natural ingredients could improve persistence of virus-based biopesticides.     

ATM mutations and phenotypes in ataxia-telangiectasia families in the British Isles: expression of mutant ATM and the risk of leukemia, lymphoma, and breast cancer.

We report the spectrum of 59 ATM mutations observed in ataxia-telangiectasia (A-T) patients in the British Isles. Of 51 ATM mutations identified in families native to the British Isles, 11 were founder mutations, and 2 of these 11 conferred a milder clinical phenotype with respect to both cerebellar degeneration and cellular features. We report, in two A-T families, an ATM mutation (7271T-->G) that may be associated with an increased risk of breast cancer in both homozygotes and heterozygotes (relative risk 12.7; P=. 0025), although there is a less severe A-T phenotype in terms of the degree of cerebellar degeneration. This mutation (7271T-->G) also allows expression of full-length ATM protein at a level comparable with that in unaffected individuals. In addition, we have studied 18 A-T patients, in 15 families, who developed leukemia, lymphoma, preleukemic T-cell proliferation, or Hodgkin lymphoma, mostly in childhood. A wide variety of ATM mutation types, including missense mutations and in-frame deletions, were seen in these patients. We also show that 25% of all A-T patients carried in-frame deletions or missense mutations, many of which were also associated with expression of mutant ATM protein.     

Activity losses among T4 lysozyme variants after adsorption to colloidal silica

Maintaining a specific molecular conformation is essential for the proper functioning of an enzyme. A substantial loss of catalytic activity can occur from the displacement caused by even a single amino acid substitution. Activity may also be lost as an enzyme undergoes a conformational change during adsorption. In this study, we investigated the effect of thermostability on the activities of three T4 lysozyme variants after adsorption to 9 nm colloidal silica particles. Less-stable T4 lysozyme variants lost more activity after adsorption than did more stable variants, apparently because they experienced more extensive structural alteration.