Don’t let the sun go down on me
An article from the weird side of science, via the ever amusing NCBI ROFL blog. Some intrepid scientists wondered what happens to microorganisms during a total solar eclipse. Researchers at the Institute of Medical Sciences, Mangalore, India waited until a total solar eclipsed occurred in their vicinity. On 15 January, 2010, their patience was rewarded with an eclipse that lasted for several hours, with a period of totality of around 10 minutes.
The experiment was simple: they took nutrient agar slants of Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Candida albicans, and exposed them to sunlight (very dim) during the eclipse, and to normal sunlight. Following exposure, cultures were streaked onto blood agar to isolate single colonies. These colonies were then assayed for antimicrobial sensitivity to a panel of 6 antibiotics using the Kirby-Bauer assay.
|Antibiotics||Normal sunlight (mm)||Solar eclipse phase (mm)|
|Aztreonam (30 μg)||24||22|
|Amikacin (30 μg)||24||22|
|Piperacillin (100 μg)||24||21|
|Ceftazidime (30 μg)||25||25|
|Ciprofloxacin (5 μg)||40||37|
Well, as you can see, there’s not much difference. I didn’t notice any standard error notations in the table, and the methods doesn’t give an indication of replicates in the study. The researchers indicate that there were “morphological” changes in the appearance of organism by microscopy, but do not include any photographs in the report.
An experiment was performed with the yeast, Candida albicans, which they call a comet assay to analyze the integrity of DNA using a method I am not familiar with. With this assay, they were unable to detect any significant changes in the yeast DNA, and end their results with this comforting statement:
which indicates that there may be no major impact of solar eclipse on human beings.
Good to know there, because in May 2012 (2012!!!!!) there will be a partial eclipse over most of the southern half of North America. I was planning on being in Europe then, just in case.
BONUS: Click through to the Pubmed article linked above. Find something, anything that might lead you to have a problem with the study.