No abstract

Over the past 50 years, many millions of European honey bee (Apis mellifera) colonies have died as the ectoparasitic mite, Varroa destructor, has spread around the world. Subsequent studies have indicated that the mite's association with a group of RNA viral pathogens (Deformed Wing Virus, DWV) correlates with colony death. Here, we propose a phenomenon known as superinfection exclusion that provides an explanation of how certain A. mellifera populations have survived, despite Varroa infestation and high DWV loads. Next-generation sequencing has shown that a non-lethal DWV variant ‘type B' has become established in these colonies and that the lethal ‘type A' DWV variant fails to persist in the bee population. We propose that this novel stable host-pathogen relationship prevents the accumulation of lethal variants, suggesting that this interaction could be exploited for the development of an effective treatment that minimises colony losses in the future.

No abstract

A new strictly anaerobic bacterium (strain BAL-lT) has been isolated from a reed bed at Ballarat Goldfields in Australia. A number of different bacteria are able to protect themselves from arsenic. They do so by first reducing arsenate [As(V)] that has entered the cell to arsenite [As(III)] and then transporting the arsenite out of the cell; arsenate reduction does not appear to support growth (7,20). Reduction of arsenate to arsenite in anoxic environments has also been demonstrated (3, 15), but until recently the organisms responsible for this reduction and the mechanisms used were not known.

No abstract