An alternative flavin-dependent mechanism for thymidylate synthesis

Although deoxythymidylate cannot be provided directly by ribonucleotide reductase, the gene encoding thymidylate synthase ThyA is absent from the genomes of a large number of nonsymbiotic microbes. We show that ThyX (Thy1) proteins of previously unknown function form a large and distinct class of thymidylate synthases. ThyX has a wide but sporadic phylogenetic distribution, almost exclusively limited to microbial genomes lacking thyA. ThyX and ThyA use different reductive mechanisms, because ThyX activity is dependent on reduced flavin nucleotides. Our findings reveal complexity in the evolution of thymidine in present-day DNA. Because ThyX proteins are found in many pathogenic microbes, they present a previously uncharacterized target for antimicrobial compounds.     

An alternative pathway for meiotic chromosome segregation in yeast

In meiosis I of most organisms, homologous chromosomes pair, recombine, and then segregate to opposite poles of the cell. Crossing-over is normally necessary to ensure the proper segregation of the homologs. Recently developed techniques have made it possible to study meiosis with highly defined artificial chromosomes. These techniques were used to demonstrate the existence of a system capable of segregating pairs of nonrecombined artificial chromosomes, regardless of the extent of their sequence homology. This system may contribute to the high fidelity of meiosis by mediating the segregation of pairs of natural chromosomes that have failed to recombine.     

Biofumigation: An alternative strategy for the control of plant parasitic nematodes

Plant-parasitic nematodes wreak havoc on the yield and quality of crops worldwide. Damage from these pests is estimated to exceed US$100 billion annually but is likely higher due to misdiagnosis. Nematode damage may be catastrophic, but historically the solution has been damaging as well. Use of the synthetic nematicide methyl bromide(MBr) poses risks to the environment and to human health. Biofumigation, the use of plant material and naturally produced compounds to control pests, is an increasingly feasible method of pest management. The process acts through the growth or incorporation of plant material into the soil, that, over the course of its degradation, releases glucosinolates that break down into nematotoxic isothiocyanates. These secondary plant metabolites exist naturally in commonly grown plants, most of which belong to the Brassicaceae family. Research endeavors have increasingly explored the potential of biofumigation. The reaction of target pests, the selection of biofumigant, and ideal environments for efficacy continue to be evaluated. This review seeks to provide a cost and benefit assessment of the status of biofumigation for the control of plant-parasitic nematodes as an alternative to conventional methyl bromide usage.