Assessing the Risk Posed by Transgenic Virus-Resistant Trifolium Repens to Native Grasslands in Southeast Australia

In Australia, comprehensive environmental risk assessments must be performed on transgenic plants (GMOs) prior to their commercial release. A key element is the determination of whether the release of a particular GMO poses any weediness threat to the environment or other agricultural systems, which can occur by means of direct invasion or by introgression of transgenes into wild populations of the same or closely related species. For transgenic pasture plants this question could be of added importance because many of these species have been selected for traits encouraging long-term persistence and competitiveness in complex plant communities (Godfree et al., 2004a). In situations where native vegetation is of high conservation value, such as Australia, the potential for transgenic pasture plants to invade native plant communities must therefore be quantified and analysed within a rigorous risk assessment framework. Over the past three years we have investigated the level of risk posed by transgenic virus-resistant (VR) Trifolium repens (white clover) to native grasslands and woodlands in the subalpine and montane regions of southeastern Australia. We have focused on identifying the viruses present in white clover populations in the subalpine zone, on determining the floristic composition of the communities that are most at risk, and on quantifying the likely selective advantage of VR T. repens in these environments

Comparative noise performance of a coded aperture spectral imager

Novel types of spectral sensors using coded apertures may offer various advantages over conventional designs, especially the possibility of compressive measurements that could exceed the expected spatial, temporal or spectral resolution of the system. However, the nature of the measurement process imposes certain limitations, especially on the noise performance of the sensor. This paper considers a particular type of coded-aperture spectral imager and uses analytical and numerical modelling to compare its expected noise performance with conventional hyperspectral sensors. It is shown that conventional sensors may have an advantage in conditions where signal levels are high, such as bright light or slow scanning, but that coded-aperture sensors may be advantageous in low-signal condition

Clinically relevant atovaquone-resistant human malaria parasites fail to transmit by mosquito.

Long-acting injectable medications, such as atovaquone, offer the prospect of a "chemical vaccine" for malaria, combining drug efficacy with vaccine durability. However, selection and transmission of drug-resistant parasites is of concern. Laboratory studies have indicated that atovaquone resistance disadvantages parasites in mosquitoes, but lack of data on clinically relevant Plasmodium falciparum has hampered integration of these variable findings into drug development decisions. Here we generate atovaquone-resistant parasites that differ from wild type parent by only a Y268S mutation in cytochrome b, a modification associated with atovaquone treatment failure in humans. Relative to wild type, Y268S parasites evidence multiple defects, most marked in their development in mosquitoes, whether from Southeast Asia (Anopheles stephensi) or Africa (An. gambiae). Growth of asexual Y268S P. falciparum in human red cells is impaired, but parasite loss in the mosquito is progressive, from reduced gametocyte exflagellation, to smaller number and size of oocysts, and finally to absence of sporozoites. The Y268S mutant fails to transmit from mosquitoes to mice engrafted with human liver cells and erythrocytes. The severe-to-lethal fitness cost of clinically relevant atovaquone resistance to P. falciparum in the mosquito substantially lessens the likelihood of its transmission in the field

Selective synthesis of natural benzaldehyde by hydrolysis of cinnamaldehyde using novel hydrotalcite catalyst

A novel Al–Mg hydrotalcite catalyst was synthesized by using combustion synthesis with glycerol as fuel. It was fully characterized. It was used in the hydrolysis of cinnamaldehyde to produce natural benzaldehyde. This is the first report of using a heterogeneous hydrotalcite for making natural benzaldehyde. The effects of different parameters on rate of hydrolysis were studied systematically to establish the kinetics of reaction. The reaction follows pseudo first order kinetics at a fixed catalyst loading with apparent activation energy of 10.00 kcal/mol. The reaction is intrinsically kinetically controlled. The maximum conversion obtained at optimum conditions was 70% in 4 h with 100% selectivity towards natural benzaldehyde. The catalyst can be reused several times without loss of activity. Both the catalyst synthesis and application in retro-aldol reaction are novel aspects of the current work

Atom-economical selective-ring-opening reaction of glycidol with 1-naphthol catalyzed by magnesium silicate of a biogenic silica source

Ring-opening reaction is one of the most important processes in organic transformations wherein selectivity of the desired product is dependent on a number of parameters. Selective ring opening of glycidol with 1-naphthol was studied to make propanolol glycol [or 3-(1-naphthyloxy)propane-1,2-diol] over magnesium silicate as a heterogeneous catalyst. Propanolol glycol is used in the treatment of hypertension. Magnesium silicate catalyst was produced by combusting a biogenic silica source material such as rice hulls to give rich hull ash (RHA), and it was characterized by using several techniques such as X-ray diffraction, scanning electron microscopy, temperature-programmed desorption, and Brunauer–Emmett–Teller N2 adsorption. The catalyst was highly active in ring-opening reaction, and 3-(1-naphthyloxy)propane-1,2-diol was the only product. The reaction was 100% atom selective. The effects of different kinetic parameters on the rate of ring opening of glycidol with 1-naphthol were studied systematically to establish the kinetics of the reaction. Magnesium silicate derived from RHA exhibited better catalytic behavior in the production of propanolol glycol with conversions of up to 80% in 3 h with 90% selectivity. The catalyst was characterized after the reaction and found to be robust without any loss of activity

Enemy release after introduction of disease-resistant genotypes into plant–pathogen systems

Predicting the magnitude of enemy release in host–pathogen systems after introduction of novel disease resistance genes has become a central problem in ecology. Here, we develop a general quantitative framework for predicting changes in realized niche size and intrinsic population growth rate after introgression of disease resistance genes into wild host populations. We then apply this framework to a model host–pathogen system targeted by genetically modified and conventionally bred disease-resistant host lines (Trifolium repens lines expressing resistance to Clover yellow vein potyvirus) and show that, under a range of ecologically realistic conditions, the introduction of novel pathogen resistance genes into host populations can pose a quantifiable risk to associated nontarget native plant communities. In the host–pathogen system studied, we predict that pathogen release could result in an increase in the intrinsic rate of population growth of up to 15% and the expansion of host populations into some marginal environments. This approach has general applicability to the ecological risk assessment of all novel disease-resistant plant genotypes that target coevolutionary host–pathogen systems for improvement of agricultural productivity

Sulphur and nitrogen nutrition influence the response of chickpea seeds to an added, transgenic sink for organic sulphur

In order to increase the concentration of the nutritionally essential sulphur amino acids in seed protein, a transgene encoding a methionine- and cysteine-rich protein, sunflower seed albumin (SSA), was transferred to chickpeas (Cicer arietinum L). Transgenic seeds that accumulated SSA contained more methionine and less oxidized sulphur than the controls, suggesting that additional demand for sulphur amino acids from the expression of the transgene stimulated sulphur assimilation. In addition, the activity of trypsin inhibitors, a known family of endogenous, sulphur-rich chickpea seed proteins, was diminished in transgenic, SSA-containing seeds compared with the non-transgenic controls. Together, these results indicate that the reduced sulphur sequestered into SSA was supplied partly by additional sulphur assimilation in the developing transgenic seeds, and partly by some diversion of sulphur amino acids from endogenous seed proteins. Growth of chickpeas on nutrient with a high sulphur-to-nitrogen ratio increased the total seed sulphur content and the accumulation of sulphur amino acids in the seeds, and partly mitigated the effect of SSA accumulation on the trypsin inhibitor amount. The results suggest that free methionine and O-acetylserine (OAS) acted as signals that modulated chickpea seed protein composition in response to the variation in sulphur demand, as well as in response to variation in the nitrogen and sulphur status of the plant

Long-acting injectable atovaquone nanomedicines for malaria prophylaxis

Chemoprophylaxis is currently the best available prevention from malaria, but its efficacy is compromised by non-adherence to medication. Here we develop a long-acting injectable formulation of atovaquone solid drug nanoparticles that confers long-lived prophylaxis against Plasmodium berghei ANKA malaria in C57BL/6 mice. Protection is obtained at plasma concentrations above 200 ng ml-1 and is causal, attributable to drug activity against liver stage parasites. Parasites that appear after subtherapeutic doses remain atovaquone-sensitive. Pharmacokinetic–pharmacodynamic analysis indicates protection can translate to humans at clinically achievable and safe drug concentrations, potentially offering protection for at least 1 month after a single administration. These findings support the use of long-acting injectable formulations as a new approach for malaria prophylaxis in travellers and for malaria control in the field