Utilisation of phosphorus nutrient content in industrial scale plasmid DNA production: a waste minimisation study

Human gene therapy is currently seeing an increase in the use of plasmid (pDNA)-based vectors as a preferred choice of vehicle for delivery of the therapeutic gene into the body. In this regard, the environmental impacts of the waste streams from the possible industrial scale manufacture of pDNA require more detailed assessment. In this study, an initial assessment was made of the nutrient phosphorus (P) inputs to four fermentation processes recommended for the industrial scale production of pDNA for the purposes of gene therapy. Phosphorus inputs to each of the four selected fermentation processes ranged from approximately 60 mg l^?1 up to 3000 mg l^?1 in the fresh media. However, the spent media waste from each of the processes exhibited only a minor reduction in the phosphorus concentrations indicating minimal uptake of P by the microorganisms. This unutilised excess level of phosphorus nutrient within the waste streams poses a strong potential for environmental impact. Waste minimisation studies were undertaken on one model fermentation process with the aim of reducing unnecessary phosphorus input. An optimised media containing a 98% reduction in added P to the media was developed. This phosphorus-minimised media had little quantitative effect upon cell biomass produced and no effect upon the quantity or quality of pDNA produced, relative to the control media. The reduction in P requirement results in an overall cost savings of 12% per fermentation batch, would simplify subsequent wastewater treatment and would contribute to slowing the depletion rate of a valuable, finite natural resource.     

Food threshold territoriality in a water strider (Gerris remigis)

Summary Summer generation 3rd, 4th and 5th instar nymphs plus adults of Gerris remigis were satiated for 2 days in a laboratory tray then deprived of food. Within 1/2–2 days, 19 of 27 nymphs and 10 of 30 adults began to exhibit territoriality, continued being so for 3–9 days, then ceased shortly before becoming quiescent. In the field, muscid flies fed to different territorial striders at a rate of 0, 1, 2, or 3 flies/day, resulted in 8 of 10 striders (at 2 flies/day) and 10 of 10 striders (at 3 flies/day) ceasing territoriality, whereas 5 of 8 controls (at 0 flies/day) remained territorial. Thus, lower and upper food thresholds were demonstrated, the upper threshold approached both from above (laboratory study) and below (field study).     

Chemical defense: incorporation of diet-derived pyrrolizidine alkaloid into the integumental scales of a moth (<Emphasis Type="Italic">Utetheisa ornatrix</Emphasis>)

Summary. Evidence is presented that pyrrolizidine alkaloid acquired by Utetheisa ornatrix (Lepidoptera, Arctiidae) as a larva from Crotalaria foodplants is incorporated in part into the scales of the adult. A single forewing of a male or female moth may contain in the order of 6 to 13 g monocrotaline in its scale cover or about 1 to 2% of the moths systemic monocrotaline content. Based on estimates of the number of scales per forewing, the monocrotaline content of individual scales is calculated to be in the order of 0.1 and 0.2 ng monocrotaline per male and female scale, respectively. This amounts to concentrations of about 1 and 3%, values roughly at a par with the average systemic concentration (0.5-0.6%) previously determined for monocrotaline in Utetheisa. It is argued that the presence of pyrrolizidine alkaloid in the moths scale coating could account for the promptness with which adult Utetheisa are rejected by spiders. It is suggested further that chemical impregnation of scales with substances deterrent to predators may be more widespread among insects than generally assumed.     

Systemic retention of ingested cantharidin by frogs

Summary Frogs(Rana pipiens) fed on blister beetles (Meloidae) or cantharidin, retain cantharidin systemically. After cessation of feeding, they void the compound relatively quickly. Systemic cantharidin does not protect frogs against ectoparasitic feeding by leeches(Hirudo medicinalis) or predation by snakes(Nerodia sipedon). As suggested by our data, and from reports in the early literature, ingestion of cantharidin-containing frogs can pose a health threat to humans.Paper no. 95 of the seriesDefense Mechanisms of Arthropods; no. 94 is LaMunyon & Eisner, Psyche (in press)     

An equilibrium theory of queen production in honeybee colonies preparing to swarm

Summary An equilibrium model is developed which seeks to explain the regulation of queen rearing in honeybee colonies preparing to swarm. The model postulates that there is a balance between nurse bees becoming inhibited from queen rearing and nurses losing their inhibition, and that whether a colony does or does not rear queens reflects the equilibrium percentage of inhibited nurses. This model leads to a quantitative prediction about the size of a conoly's nurse population at which queen rearing should start. Comparing the model's predictions with empirical observations pinpoints data needed for a more complete explanation of control of queen rearing. In particular, the model suggests a central regulatory role for density-dependent changes in the behaviors involved in queen substance dispersal.     

Nitrogen uptake and growth of the germlings and mature thalli of Fucus distichus

Fucus distichus L. was collected near Vancouver, Canada, in late fall and early winter, 1981. The effects of the forms of nitrogen (nitrate, ammonium or urea) and periodic exposure to air on growth, rhizoid development and nitrogen uptake in germlings was investigated. Gamete release, fertilization, germination and germling growth had no requirement for a specific form of nitrogen. Periodic exposure to air increased secondary rhizoid development twofold. Nitrate and ammonium uptake rates of the germlings were higher than for the mature thalli (20 to 40 times for nitrate and 8 times for ammonium), while the halfsaturation constant (K _s) values for nitrate were similar (1 to 5 M). The germlings showed saturable uptake kinetics but the mature thalli did not. When germlings were exposed to air it caused a 70% decrease in nitrate uptake, but not change in ammonium uptake. Ammonium uptake in the mature thalli was proportional to the ambient ammonium concentration. Nitrate uptake in the mature thalli appeared to follow saturation kinetics at low nitrate concentrations, but showed a non-saturable component at concentrations greater than 10 M. Presence of ammonium inhibited nitrate uptake by the mature plants but not by the germlings.     

Evaluation of XRF and LIBS technologies for on-line sorting of CCA-treated wood waste

Contamination of wood waste with chromated copper arsenate greatly limits recycling opportunities for the wood waste as a whole. Separation of CCA-treated wood from other wood types is one means by which such contamination can be removed. The purpose of the current study was to evaluate two detector technologies for sorting CCA-treated wood from other wood types. The detector technologies evaluated included X-ray fluorescence spectroscopy (XRF) and laser induced breakdown spectroscopy (LIBS). The XRF detector system utilized in this study was capable of rapidly detecting the presence of CCA in painted wood, wet wood, heartwood, sapwood, and at portions of the wood containing knots. Furthermore, the XRF system was capable of distinguishing between CCA-treated wood and wood treated with alternative wood treatment preservatives, but was limited by the fact that it was not designed for on-line operation so tests were conducted in a batch mode on a conveyor. The analysis time used in this study (3 s) can be decreased significantly for an XRF system designed specifically for on-line operation. The LIBS system developed for this study was found to effectively identify CCA-treated wood for pieces ranging in thickness from 1 to 8 cm. High sorting efficiencies were noted when 10 laser shots were taken on a piece of wood. Furthermore, the LIBS system was found to be effective for identifying wood that has been coated with stains and paints in addition to identifying wood that has been CCA treated. The major drawback with the LIBS system developed in this study was the limited laser pulse energy. With an increase in laser pulse energy it is anticipated that the working focal length of the LIBS system can be increased to enable the monitoring of wood samples of more variable thicknesses. Limitations associated with analysis of very rotted pieces of wood and wet wood can also be overcome by using a higher pulse energy laser. Overall, both technologies show incredible promise for sorting CCA-treated wood from other wood types. The next recommended step would be to run an improved full-scale operation at one facility to document sorting efficiencies and fine-tune the improvements proposed in the current study. Such a study could potentially open-the-door for more widespread sorting of wood waste.     

Assessment of sampling and chemical analysis of source-separated organic household waste

The quality of the waste sampling procedure and chemical analysis was evaluated in a research program on characterization of organic waste obtained after disc screening of source-separated organic household waste. The sampling procedures focused on a truckload of waste and involved several steps of subsampling including shredding, mixing, blending, high-speed-blending, drying and milling prior to analysis of the organic waste with respect to ash content, crude fibers, crude fat, crude protein, sugar, starch, enzyme-digestible organic matter, P, N, C, H, S and calorific value. The statistical evaluation of the procedures involved 10 samples of the same truckload of waste obtained by splitting the sample at each level in the procedure according to a staggered, incomplete nested statistical design. Furthermore, one sample was analysed six times over a period of approximately one year. The statistical evaluation showed that no single step in the sampling procedure contributed with excessive variance and that the variance caused by the sampling procedure was approximately the same as the variance in the chemical analysis observed over a year. The variance varied with the analytical parameter but for most parameters the uncertainty was satisfactorily low (of the order of 3-10% expressed as the relative standard deviation, which is considered to be satisfactory for waste characterization).     

The living environment and children's fears following the Indonesian tsunami

The tsunami that struck South-east Asia on 26 December 2004 left more than 500,000 people in Aceh, Indonesia, homeless and displaced to temporary barracks and other communities. This study examines the associations between prolonged habitation in barracks and the nature of fears reported by school-age children and adolescents. In mid-2007, 30 months after the tsunami, the authors interviewed 155 child and parent dyads. Logistic regression analysis was used to compare the fears reported by children and adolescents living in barracks with those reported by their peers who were living in villages. After adjusting for demographic factors and tsunami exposure, the data reveals that children and adolescents living in barracks were three times more likely than those living in villages to report tsunami-related fears. The study demonstrates that continued residence in barracks 30 months after the tsunami is associated with higher rates of reporting tsunami-related fears, suggesting that barracks habitation has had a significant impact on the psychological experience of children and adolescents since the tsunami.