Effects of incubation temperature on the dose-survival time relationship of Trichoplusia ni larvae infected with Autographa californica nucleopolyhedrovirus.

The interaction between virus multiplication and host development was studied by determining the survival time of Trichoplusia ni larvae inoculated with a wide range of doses of Autographa californica nucleopolyhedrovirus and incubated at five different temperatures spanning the biologically relevant range. The results support earlier findings that the course of baculovirus infection follows the mathematical description of the birth-death model. Both in vivo rate of virus increase and larval growth rate increased linearly with increasing temperature from 14 to 29 degrees C; developmental zeros for virus replication and larval growth were estimated from these data to be 10.2 and 10.4 degrees C, respectively. The data were used to generate a description of the combined effects of dose and temperature on median survival time at doses greater than the LD(50). Implications of the lag times before onset of viral replication and between cessation of replication and larval death with respect to model-based estimation of the critical population level (i.e., amount of virus in the host just prior to death) are discussed.

N-Linked glycosylation of a baculovirus-expressed recombinant glycoprotein in insect larvae and tissue culture cells.

The potential of insect cell cultures and larvae infected with recombinant baculoviruses to produce authentic recombinant glycoproteins cloned from mammalian sources was investigated. A comparison was made of the N-linked glycans attached to secreted alkaline phosphatase (SEAP) produced in four species of insect larvae and their derived cell lines plus one additional insect cell line and larvae of one additional species. These data survey N-linked oligosaccharides produced in four families and six genera of the order Lepidoptera. Recombinant SEAP expressed by recombinant isolates of Autographa californica and Bombyx mori nucleopolyhedroviruses was purified from cell culture medium, larval hemolymph or larval homogenates by phosphate affinity chromatography. The N-linked oligosaccharides were released with PNGase-F, labeled with 8-aminonaphthalene-1-3-6-trisulfonic acid, fractionated by polyacrylamide gel electrophoresis, and analyzed by fluorescence imaging. The oligosaccharide structures were confirmed with exoglycosidase digestions. Recombinant SEAP produced in cell lines of Lymantria dispar (IPLB-LdEIta), Heliothis virescens (IPLB-HvT1), and Bombyx mori (BmN) and larvae of Spodoptera frugiperda, Trichoplusia ni , H.virescens , B.mori , and Danaus plexippus contained oligosaccharides that were structurally identical to the 10 oligosaccharides attached to SEAP produced in T.ni cell lines. The oligosaccharide structures were all mannose-terminated. Structures containing two or three mannose residues, with and without core fucosylation, constituted more than 75% of the oligosaccharides from the cell culture and larval samples.

Placebo-controlled comparison of the efficacy and tolerability of once-daily moxonidine and enalapril in mild-to-moderate essential hypertension.

OBJECTIVES: To compare the antihypertensive efficacy and tolerability of the imidazoline I1 receptor agonist moxonidine, a centrally acting antihypertensive, with the angiotensin converting enzyme inhibitor enalapril. DESIGN: An 8-week, double-blind, randomized, placebo-controlled study involving 140 outpatients with mild-to-moderate essential hypertension. METHODS: Outpatients with WHO stage I or II hypertension were enrolled in the study. After a 4-week placebo-controlled stabilization phase patients were allocated randomly to placebo, 0.2 mg moxonidine once a day or 5 mg enalapril once a day for 2 weeks. Dosages were then doubled to 0.4 mg moxonidine once a day or 10 mg enalapril once a day for a further 6 weeks. Blood pressure responses to therapy were measured by conventional office techniques and by 24 h ambulatory blood pressure monitoring. RESULTS: The mean reduction in sitting blood pressure with moxonidine was similar to that with enalapril (19.5 +/- 16.0/12.3 +/- 8.7 versus 18.9 +/- 13.7/11.8 +/- 8.0 mmHg) and significantly superior to that with placebo (-4.6 +/- 12.3/-4.7 +/- 6.8 mmHg, P< 0.001). In addition to reducing blood pressure during conventional measurements, moxonidine administration reduced blood pressure throughout 24 h ambulatory measurements. The trough:peak ratio for moxonidine was 0.7. Both moxonidine and enalapril were tolerated well. CONCLUSIONS: Moxonidine is an effective and well-tolerated antihypertensive, at least as good as other established forms of antihypertensive medication. The trough:peak ratio of 0.7 indicates that the drug will be effective administered once a day.

Antioxidant responses to simulated acid rain and heavy metal deposition in birch seedlings.

This study measured the responses of different anti-oxidants in 2-year-old birch (Betula pendula Roth) seedlings subjected to simulated acid rain (pH 4.0) and heavy metals (Cu/Ni), applied alone or in combination for 2 months. The applied concentrations of pollutants did not significantly affect seedling biomass or total glutathione levels. Acid rain alone increased superoxide dismutase (SOD) activity both in leaves and roots, while heavy metals alone inhibited SOD activity in roots. Both acid rain and heavy metals applied singly increased ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) activities in leaves but decreased activities in roots. In contrast, acid rain and heavy metal treatments increased glutathione reductase (GR) activity in roots but not in leaves. Spraying birch seedlings with a mixture of acid rain and heavy metals increased SOD, APX and GPX activities in leaves and GR activity in roots. However, the effects of mixed pollutants on enzyme activities usually were less than the summed effects of individual pollutants. Enzyme responses also depended on where pollutants were applied: spraying pollutants onto the shoots initiated higher responses in SOD, APX and GPX than did application to the soil surface, while the opposite was true for GR.

In vivo production, stabilization, and infectivity of baculovirus preoccluded virions.

Wild-type and polyhedrin-negative isolates of Autographa californica nuclear polyhedrosis virus were replicated in fifth-instar Trichoplusia ni larvae. Insect tissues infected with wild-type virus contained two types of virions that are highly infectious when ingested, those occluded in polyhedra and preoccluded virions. Tissue infected with the polyhedrin-negative virus contained only preoccluded virions. The relative potencies of the two types of infected tissue were determined by dose-mortality bioassays by using the neonate droplet feeding procedure. On a fresh weight basis, preparations of tissues infected with the polyhedrin-negative virus were approximately four times more potent than equivalent preparations of tissue infected with wild-type virus. Approximately half of the observed potency of the wild-type-virus preparations was due to polyhedra, and the remaining activity was due to preoccluded virions present in the tissue. The potency of the polyhedrin-negative preparations was not reduced significantly by lyophilization. The polyhedrin-negative isolate produced about 60% more infectious virus per unit of larval weight than did the wild-type isolate. The ability to produce large amounts of high-potency viral preparations in larvae and the convenience of being able to lyophilize the preparations for long-term storage shows promise for the use of preoccluded virus preparations as biopesticides.

Limitations of the Cornell - Mcguirre earthquake risk method - an engineering viewpoint for Australia

The need to consider earthquake loading as an important element in building desing in Australia, especially when undertaking desings for emergency and critical facilities and high - occupancy type structures, is now accepted. For the purpose of integrating such earthquake load parameters into desings, recommendations in the form of regulations or as a code are required. Thesetechnical and indeed legally binding regulations have received little attention in the pastbecause of the perception that Australia has "low" seismicity and hence a "low" risk (AU)

Engineering implications for continental earthquakes inferences from the 1989 Newcastle, Australia earthquake

This paper considers the engineering implications based upo the Newcastle Earthquake of 1989, for continental earthquake in an area were little or no preparation was considered necessary. The lack of structural adequacy of building to withstand loadings other than gravity loads has never been fully tested in Australia before in a major urban environment the size of Newcastle. The consequences of what similarevents occurring in sydney, Brisbane or Melbourne could cause, a far greater scale, are lessons from the Newcastle Earthquake (AU)

Influence of ozone air pollution on plant-herbivore interactions. Part 2: Effects of ozone on feeding preference, growth and consumption rates of monarch butterflies (Danaus plexippus).

Effects of ozone fumigation of Asclepias curassavica L. and A. syriaca L. on feeding preference, growth, development, and nutritional indices of monarch larvae were investigated in conjunction with changes in specific leaf metabolites. While foliar chemistry was quite variable, fumigation generally decreased sugars and proteins, and increased amino acids and phenolics in A. curassavica. Effects were similar in A. syriaca except that sugars were generally increased while amino acids were usually not affected. On A. curassavica, 3rd instar larvae preferred ozone-treated leaves while 4th instars showed no preference; conversely, on A. syriaca, 3rd instars showed no preference while 4th instars preferred control leaves. Relative growth rate and relative consumption rate of 5th instars were greater on fumigated plants of both species, but other nutritional indices were unaffected. Larvae developed more rapidly on intact fumigated plants of both species than on the respective controls. The results suggest that enhanced feeding stimulation may be the primary cause of the altered behavior and performance on ozone-fumigated plants.

Influence of ozone air pollution on plant-herbivore interactions. Part 1: Biochemical changes in ornamental milkweed (Asclepias curassavica L.; asclepiadaceae) induced by ozone.

A series of fumigation experiments was conducted with bloodflower (Asclepias curassavica L.) in continuous-flow stirred reactors (CSTRs) to elucidate the effects of ozone on foliar concentrations of several primary and secondary plant metabolites relevant to herbivores. Plants 8 weeks of age were subjected to different ozone levels ranging from 0 to 134 nl liter(-1) for exposure periods up to 16 days. Leaves were analyzed for concentration of soluble carbohydrates, starch, free amino acids, soluble protein, total phenolics, and total cardenolides. Significant interactions between the linear effects of ozone concentration and exposure time were found for soluble carbohydrates, amino acids, cardenolides and phenolics. No significant treatment effects could be observed on foliar starch and protein concentration. The metabolic responses of plants to fumigation appeared to be altered by overall plant nutrition. It is possible that the metabolic changes observed in the host plant represent important changes in nutritional quality to insects.

Co-occlusion and persistence of a baculovirus mutant lacking the polyhedrin gene.

A co-occlusion process was evaluated as a commercially and ecologically acceptable strategy for the development of genetically improved baculovirus insecticides. Coinfection of Spodoptera frugiperda (IPLB-SF-21) tissue culture cells with Autographa californica nuclear polyhedrosis virus (AcMNPV) and an AcMNPV mutant (Ac-E10) lacking the polyhedrin gene resulted in occlusion of both virus types within polyhedra. The amount of occluded Ac-E10 virions in progeny polyhedra populations during serial passage in Trichoplusia ni larvae was evaluated. Maintenance of the mutant in progeny polyhedra required polyhedra inocula containing equal numbers of the two virus types at a high dose. A significant reduction in occluded mutant nucleocapsids occurs with inoculum levels below a 100% lethal dose. At inoculum levels below a 30% lethal dose, the majority of fourth-instar larvae were infected with only one type of virus. The commercial application and ecological advantages of the co-occlusion process are discussed.

Rate of increase of Autographa californica nuclear polyhedrosis virus in Trichoplusia ni larvae determined by DNA:DNA hybridization.

The rate of increase and doubling time of the HOB clone of Autographa californica nuclear polyhedrosis virus (AcMNPV-HOB) in neonate Trichoplusia ni larvae was determined by measuring the increase in viral DNA through time following inoculation with average doses of 50 or 17,400 occlusion bodies per larva. Changes in total DNA and viral DNA through time were followed by fluorescence spectroscopy and quantitative slot-blot DNA:DNA hybridization, respectively. Total DNA content (i.e., larval DNA and viral DNA) of larvae infected with the intermediate dose lagged behind that of noninfected larvae 30 hr post-inoculation (p.i), reached a maximum at 51 hr p.i., and stayed constant thereafter. The total DNA content of larvae inoculated with the high dose lagged behind that of the control group from 18 hr p.i. and increased slowly until death of the larvae (ca. 48 hr p.i.). The amount of viral DNA in larvae inoculated with the intermediate dose increased exponentially between 15 and 42 hr p.i., reached a maximum at 48 hr p.i., and stayed constant until 68 hr p.i., by which time most larvae had died. The amount of viral DNA in larvae inoculated with the high dose did not increase exponentially; initially the rate of increase was the same as that for larvae inoculated with the intermediate dose but became progressively lower after 13 hr p.i. Calculations of the rate of increase for AcMNPV-HOB in neonate T. ni larvae inoculated with the intermediate dose and incubated at 29 degrees C resulted in a value of 0.264 hr-1 (doubling time: 2.63 hr).(ABSTRACT TRUNCATED AT 250 WORDS)

Rate of increase and critical amount of nuclear polyhedrosis virus in lepidopterous larvae estimated from survival time assay data with a birth-death model.

A birth-death model developed for pathogens of vertebrates was used to estimate the in vivo rate of increase (alpha) and the doubling time (td) from survival time assay data. Host-pathogen combinations used in this study were two Autographa californica nuclear polyhedrosis virus isolates in Trichoplusia ni and Heliothis zea NPV in H. zea. The alpha's, estimated as he negative reciprocal of the slope of the linearly decreasing section of the plot of median survival times against the logarithm of inoculum concentration, were calculated in two ways. First, simple regression was used to fit a line through the linearly decreasing part using data points selected by eye; secondly, a three-phase segmented linear regression model was used and alpha was estimated from the slope of the middle segment. Estimates of alpha (and td) were 0.338 (2.05), 0.274 (2.53) and 0.243 h-1 (2.85 h) using the simple regression method, and 0.385 (1.80), 0.305 (2.27) and 0.223 h-1 (3.11 h) using the 3-phase segmented linear regression model for AcMNPV-1A, AcMNPV-HOB and HzSNPV, respectively. Although AcMNPV-HOB killed larvae faster (6 to 13 h) than AcMNPV-1A, it multiplied more slowly. Estimates for the critical number ranged from 4.8 x 10(9) to 4.5 x 10(14) genome copies for HzSNPV in H. zea larvae and AcMNPV-1A in T. ni larvae, respectively. The significance of the calculated critical numbers is discussed.

Inhibition by purines of the inotropic action of isoprenaline in rat atria.

The effects of a series of adenosine derivatives were examined on the catecholamine-stimulated electrically-driven rat left atrium in vitro. All the purines tested reduced the positive inotropic action of isoprenaline, 0.1 microM, with the potency order: L-N6-phenlylisopropyladenosine (L-PIA) greater than 5'-N-ethylcarboxamide adenosine (NECA) greater than D-PIA greater than 2-chloroadenosine greater than adenosine. Dipyridamole did not change the IC50 of adenosine. The adenosine deaminase inhibitor, 2'deoxycoformycin, produced a small but nonsignificant shift to the left of the adenosine concentration-response curve. The cardiac depressant effects of these purines were reversed by theophylline and the IC50 values were unchanged in the presence of atropine or in atria taken from reserpine-treated rats. It is concluded that the purine receptor mediating these effects should not be classified on the A1/A2 system. The relationship between functionally characterized purine receptors and those originally defined as modulating adenylate cyclase is discussed.

Inhibitory action of gamma-aminobutyric acid on the excitatory but not inhibitory innervation of the rat anococcygeus muscle.

1 The effects of gamma-aminobutyric acid (GABA), ethylenediamine, 3-aminopropane sulphonic acid and (+/-)-baclofen have been examined on the responses to stimulation of the adrenergic excitatory and non-adrenergic non-cholinergic inhibitory innervation of the rat anococcygeus muscle in vitro. 2 GABA produced a dose-related depression of the contractile responses to field stimulation. Ethylenediamine and baclofen also depressed the contractile responses, though they were less potent than GABA. 3-Aminopropane sulphonic acid was almost inactive. The inhibitory action of GABA was not modified by phentolamine, propranolol or bicuculline methylbromide. 3 GABA did not affect the contractile responses of the anococcygeus muscle to noradrenaline, phenylephrine or carbachol in untreated muscles or those treated with 6-hydroxydopamine in vitro. 4 In preparations in which tone was raised by continuous perfusion with carbachol in the presence of phentolamine, field stimulation relaxed the muscle. GABA had no effect on this inhibitory response, and did not itself produce any relaxation. 5 It is concluded that GABA exerts a presynaptic inhibitory action on the excitatory adrenergic but not on the inhibitory innervation of the anococcygeus muscle, and that the GABA receptor involved exhibits properties of the previously described GABAB site.

Western pine beetle: specificity among enantiomers of male and female components of an attractant pheromone.

The flight response of both sexes of Dendroctonus brevicomis to the mixture of myrcene, racemic frontalin, and (1R,5S,7R)-(+)-exo-brevicomin and to the mixture of myrcene, (1S,5R)-(-)-frontalin and racemic exo-brevicomin was significantly greater than the response to the same mixtures in which the antipodes were substituted. The flight response to these two mixtures was also greater than the response to the ternary mixture of myrcene, racemic frontalin, and racemic exo-brevicomin (MFE). The walking response of both sexes to the mixture of myrcene, racemic frontalin, and (+)-exo-brevicomin was not different from the response to MFE. Substitution of the antipode lowered the response when compared to that of MFE. When evaporated with ponderosa pine turpentine, (-)-frontalin was active in the field while its antipode was not.

Selective production of cis- and trans-verbenol from (-)-and (+)-alpha by a bark beetle.

A unique biological system whereby optical isomers are selectively transformed to geometrical isomers is demonstrated in Ips paraconfusus. Exposure of adult male and female beetles to vapor of (-)-alpha-pinene resulted in the production of (+)-cis-verbenol, a pheromone of this species, whereas (+)-alpha-pinene was oxidized to (+)-trans-verbenol. It appears, therefore, that the ability of a bark beetle to produce its aggregation pheromone can be governed by the chirality of a precursor in the host tree.