Friday, September 04, 2009

genomic study yields plausible cause of colony collapse disorder


Infection Research | Researchers report that they have found a surprising but reliable marker of colony collapse disorder (CCD), a baffling malady that in 2007-2008 killed off more than a third of commercial honey bees in the U.S. Their study, in the Proceedings of the National Academy of Sciences, is the first to identify a single, objective molecular marker of the disorder, and to propose a data-driven hypothesis to explain the mysterious disappearance of American honey bees.

The new study made use of the genome and a genome-based tool, the microarray, to look for differences in gene expression in the guts of healthy honey bees and in those from hives afflicted by CCD. Such microarray analyses normally identify only active genes. But Reed Johnson, a University of Illinois doctoral student in entomology and first author on the study, noticed that the microarrays were turning up large quantities of fragmented ribosomal RNA (rRNA) in the bees affected by CCD.

Ribosomes are the factories in which proteins are made, but Johnson observed that this rRNA contained adenosine-rich sequences not seen in normal ribosomes. Such "polyadenylation" is believed to be a sign of ribosome degradation. "The one consistent indicator of CCD across samples collected at multiple times and in multiple places was the overabundance of ribosomal fragments," entomology professor and department head May Berenbaum said.

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