> I wrote: > Looks like the astronauts have been lucky so far and > in retrospect justifies the extremes of quarantine > post-return (well, and pre-flight too) from > missions: <snip>
I'd meant to look up a more technical article for those so-inclined; here is one: http://www.sciencedaily.com/releases/2007/09/070924151126.htm ...Their results, published in the journal Proceedings of the National Academy of Sciences, reveal a key role for a master regulator, called Hfq, in triggering the genetic changes that show an increase in the virulence of Salmonella as a result of spaceflight..."We chose to measure gene expression at the mRNA level since the technique to do this, called microarray analysis, is a highly advanced and convenient way to quantitatively measure the expression of every gene in a single experiment," said Wilson, who coordinated the team's molecular profiling efforts for the Nickerson lab, and played a central role in the performance of these experiments, including data analysis. "It is a very powerful technique that was very applicable to the spaceflight experiment. The isolation of mRNA poses particular challenges since it is very sensitive to degradation, but we designed the experiment using a fixative that preserved the mRNA very well." ...The study discovered that an important regulatory protein, Hfq, may be a key molecule responsible for the increased virulence due to space flight. "Hfq is a protein that binds to and regulates a number of regulatory RNAs, which in turn, control gene expression," said Nickerson. "Our studies suggest that there may be a role for these regulatory RNAs in the cellular response to the physical and mechanical forces found in spaceflight, which are relevant to conditions that cells encounter here on Earth during the normal course of their lifecycles." These results have important implications for human health since Salmonella (and other gut-related bacterial pathogens) are a leading cause of food-borne illness and infectious disease, especially in the developing world. Nickerson's group further highlights Hfq as a potential therapeutic target, since no vaccine currently exists for Salmonella food-borne infections in humans. In addition, the space flight studies may shed new light on why Salmonella has become increasingly resistant to antibiotic treatment... This one adds some interesting info too: http://www.the-scientist.com/news/home/53627/ ...Some research has indicated that Hfq expression should increase with increasing virulence, making the decrease in Hfq "particularly puzzling," according to Lionello Bossi of the National Center of Scientific Research in France, who was not a co-author. But other work has shown that bacterial virulence can sometimes increase when classic virulence genes are down-regulated, Nickerson said. "This suggests exciting new insight in terms of how these pathogens are causing disease in our body." It's thought that the space between microvilli protrusions on intestinal cells creates a free-fall environment much like that encountered in outer space, explained co-author Kerstin Höner zu Bentrup of Tulane University Health Sciences Center in New Orleans. "We can actually mimic now what's going on in an environment that Salmonella sees in your gut shortly before it infects the cells." According to Laura Frost of the University of Alberta in Canada, who was not involved in the study, activation of Hfq-controlled genes is good evidence that stress responses are activated in bacteria grown in space. "The interesting thing about this experiment is that low gravity appears to be a stress that the bacteria can detect." The authors also found that flight samples showed evidence of increased biofilm formation, which could help explain their increased virulence, said Höner zu Bentrup. "Biofilm formation is a major player in virulence," largely because bacteria aggregated in biofilms are less susceptible to host defense mechanisms, she told The Scientist... There's a list of lots more articles at the end of that, as well as a disagreement from a PhD about the conclusion. It makes sense to me that gene expression could change under zero-gee, as adaptation (of behavior, of growth requirements, eventually by gene-selectio) is pretty much what all living things must do when their environmnet changes. Debbi Worms In Space Maru ____________________________________________________________________________________ Be a better Globetrotter. Get better travel answers from someone who knows. Yahoo! Answers - Check it out. http://answers.yahoo.com/dir/?link=list&sid=396545469 _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
