[permaculture] BBC NEWS | Science & Environment | DNA clue to honey bee deaths
Lawrence F. London, Jr.
lflj at intrex.net
Tue Aug 25 12:18:03 EDT 2009
Page last updated at 20:57 GMT, Monday, 24 August 2009 21:57 UK
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DNA clue to honey bee deaths
By Judith Burns
Science and Environment reporter, BBC News
Multiple viruses may act together to cause colony collapse
Scientists say that mass bee deaths may be caused by viruses that disrupt gene expression.
The team analysed which genes were turned on and which were turned off in healthy bees and those from hives with colony
collapse disorder (CCD).
Since 2006, CCD has caused the catastrophic loss of US bee hives and is implicated in bee deaths elsewhere.
Writing in PNAS journal, the team say they used "whole genome microarrays" to compare cells from bees' guts.
Lead scientist May Berenbaum from the University of Illinois told BBC News that the research was made possible by
publication of the bee genome in 2006.
We talk about a smoking gun. We have the bullet hole!
Professor May Berenbaum
"It's an incredibly useful repository of information which allowed the construction of the microarray - a slide which
has all 10,000 bee genes on it," she said.
"We used it to compare colony collapse disorder bees with healthy ones and looked at the differences. There are of
course 10,000 genes. So there were a whole lot of differences but we could rule out many of them."
The team concentrated on analysing gene expression from cells in the bees' guts because this is the primary site of
pesticide detoxification and immune defence.
Previous theories for CCD have included pesticide poisoning as well as infection and mite infestation.
But the team's genetic analysis of the bees' guts failed to reveal elevated expression of pesticide response genes.
In addition, genes involved in immune response showed no clear expression pattern despite the increased prevalence of
viruses and other pathogens in CCD colonies.
What did show up in the guts of the CCD bees was an abundance of fragments from the ribosome, a structure which is the
cell's protein making factory.
According to the researchers, this finding suggests that protein production is likely to be compromised in bees from CCD
Previous research shows that the viruses that bees carry all attack the ribosome.
The microbes in question are known as "picorna-like" viruses. The word derives from pico, which means little, and RNA
"These picorna-like viruses all attack at the same spot," said Professor Berenbaum.
"What they do is to work their way into the ribosome and instead of making honey bee protein they make virus proteins.
"So maybe what's happening is basically the ribosome wears out. So we looked to see if the CCD bees have more of these
viruses than healthy bees. And they do.
The viruses in question include "deformed wing virus" and "Israeli acute paralysis virus".
The scientists believe that if a number of similar picorna-like viruses attack simultaneously, they may be able to
overwhelm the ribosome.
"We talk about a smoking gun. We have the bullet hole!" said May Berenbaum.
"We now need to look for how multiple viruses might interact on the ribosome."
The honey bee is the US's key agricultural pollinator. As such it is worth $14bn to the country's economy.
CCD was first identified in 2006. In the winter of 2007-8 more than a third of US bees were lost.
Similar losses have been reported in Europe, giving rise to fears that CCD is a global problem.
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12 Feb 08 | Magazine
RELATED INTERNET LINKS
University of Illinois Dept of Entomology
Bee Research Laboratory, US dept of agriculture
British Beekeepers association
The BBC is not responsible for the content of external internet sites
-------- Original Message --------
Subject: [SANET-MG] Changes in transcript abundance relating to colony collapse disorder in honey bees
Date: Mon, 24 Aug 2009 21:53:31 -0400
From: jcummins <jcummins at UWO.CA>
To: SANET-MG at LISTS.IFAS.UFL.EDU
Investigations such as th one below on perimortem changes in RNA
transcripts in CCD may prove useful .However, the comments on
pesticide response proteins and the immune response seem premature.
The pesticide response of the bee transcripts are not currently
available in the scientific literature. The gens effected in honey bee
by neonicotinoid pesticides, for example are not yet fully identified.
or at least published on. The immune response of honey bee to bacterial
pathogens are pretty well characterized but the immune response to
viruses is less fully identified. Nevertheless, the work described below
provides a useful start to clearing up the molecular biology of CCD.
PNAS published online before print August 24, 2009,
Changes in transcript abundance relating to colony collapse disorder in
honey bees (Apis mellifera)
1. Reed M. Johnsona,1,
2. Jay D. Evansb,
3. Gene E. Robinsona and
4. May R. Berenbauma,2
Colony collapse disorder (CCD) is a mysterious disappearance of honey
bees that has beset beekeepers in the United States since late 2006.
Pathogens and other environmental stresses, including pesticides, have
been linked to CCD, but a causal relationship has not yet been
demonstrated. Because the gut acts as a primary interface between the
honey bee and its environment as a site of entry for pathogens and
toxins, we used whole-genome microarrays to compare gene expression
between guts of bees from CCD colonies originating on both the east and
west coasts of the United States and guts of bees from healthy colonies
sampled before the emergence of CCD. Considerable variation in gene
expression was associated with the geographical origin of bees, but a
consensus list of 65 transcripts was identified as potential markers for
CCD status. Overall, elevated expression of pesticide response genes was
not observed. Genes involved in immune response showed no clear trend in
expression pattern despite the increased prevalence of viruses and other
pathogens in CCD colonies. Microarray analysis revealed unusual
ribosomal RNA fragments that were conspicuously more abundant in the
guts of CCD bees. The presence of these fragments may be a possible
consequence of picorna-like viral infection, including deformed wing
virus and Israeli acute paralysis virus, and may be related to arrested
translation. Ribosomal fragment abundance and presence of multiple
viruses may prove to be useful diagnostic markers for colonies afflicted
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