Comment on "Synthesis of ultra-incompressible superhard rhenium diboride at ambient pressure"

Chung et al. (Reports, 20 April 2007, p. 436) reported the synthesis of superhard rhenium diboride (ReB2) at ambient pressure. We show that ReB2, first synthesized at ambient pressure 45 years ago, is not a superhard material. Together with the high cost of Re, this makes the prospect for large-scale industrial applications of ReB2 doubtful.     

Genetic loci affecting resistance to human malaria parasites in a West African mosquito vector population

Successful propagation of the malaria parasite Plasmodium falciparum within a susceptible mosquito vector is a prerequisite for the transmission of malaria. A field-based genetic analysis of the major human malaria vector, Anopheles gambiae, has revealed natural factors that reduce the transmission of P. falciparum. Differences in P. falciparum oocyst numbers between mosquito isofemale families fed on the same infected blood indicated a large genetic component affecting resistance to the parasite, and genome-wide scanning in pedigrees of wild mosquitoes detected segregating resistance alleles. The apparently high natural frequency of resistance alleles suggests that malaria parasites (or a similar pathogen) exert a significant selective pressure on vector populations.     

The calicheamicin gene cluster and its iterative type I enediyne PKS

The enediynes exemplify nature's ingenuity. We have cloned and characterized the biosynthetic locus coding for perhaps the most notorious member of the nonchromoprotein enediyne family, calicheamicin. This gene cluster contains an unusual polyketide synthase (PKS) that is demonstrated to be essential for enediyne biosynthesis. Comparison of the calicheamicin locus with the locus encoding the chromoprotein enediyne C-1027 reveals that the enediyne PKS is highly conserved among these distinct enediyne families. Contrary to previous hypotheses, this suggests that the chromoprotein and nonchromoprotein enediynes are generated by similar biosynthetic pathways.     

Pest management programmes in vineyards using male mating disruption

Israeli vine growers have been reluctant to adopt the mating disruption technique for control of the European vine moth, Lobesia botrana Den. & Schiff. Since the chemically controlled honeydew moth, Cryptoblabes gnidiella Mill., coexists with the European vine moth, growers have maintained that the use of mating disruption would fail to bring about a significant reduction in pesticide use. In this study, the efficacy of mating disruption techniques against C. gnidiella was tested, as well as the effect of these methods on pesticide use and damage to clusters when the method was employed against both of the pests in wine grapes. Comparisons were made between plots treated with (1) L. botrana mating disruption pheromone, (2) L. botrana and C. gnidiella mating disruption pheromones and (3) control plots. A significant difference in the number of clusters infested with the developmental stages of the moths was seen between pheromone-treated plots and controls, while no such difference was observed between plots treated with one versus two pheromones. A similar pattern was observed in the number of insecticide applications; the greatest number of applications was used in control plots, followed by plots treated with L. botrana mating disruption pheromone and by plots treated with pheromones against both pests, in which no pesticides were applied.