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Science News You Can Use —David Chu

Replacing fin clipping with skin swabbing for DNA When you think about it, working with zebrafish isn’t all that different than working with mice. You must provide zebrafish with a proper life support system, adequate opportunities for expressing normal behaviors, and use them in a humane fashion. Regarding the latter, taking a biopsy sample for DNA analysis is very much so like how it’s done in mice but instead of taking a small bit of tail tip, in laboratory fish you take a small piece of the caudal fin. Fish scale is a type of modified skin and normally are covered with a mucus layer full of cells and antimicrobial properties. Swabbing surface of fish can pick up these cells and this method of DNA collection is already being used in field studies and aquaculture. Recently, scientists at University of Leicester reported in Zebrafish (volume 13, number 6; DOI 10.1089/zeb.2016.1348) that this non-invasive method is also valid for working with small laboratory fish such as zebrafish and three-spined sticklebacks. Body swabs allow scientists to quickly sample fish for DNA without use of anesthetics or causing physical damage to the fish themselves. Amazingly, even though there was a perceived possibility of DNA cross contamination (ie multiple fish living in the same recirculating rack), Carl Breacker and colleagues reported that there was no evidence of cross contamination using body swab method.

Restraining an awake stickleback for skin swabbing.

Treating mouse ulcerative dermatitis scientifically validated You’ve seen it, we’ve all seen it. A mouse starts to scratch itself seemingly out of the blue and diagnostics show no evidence of external parasites and no ointments and topical remedies help to alleviate that mouse’s itch.

Mouse restrainer schematics.

It’s called murine ulcerative dermatitis or MUD. By now most everyone is using nail trim as a low cost, high efficacy method to treat valuable mice exhibiting MUD. This method was developed more than a decade ago and slowly gained acceptance through word of mouth, anecdotes, and meeting poster presentations. Recently, Sean Adams and colleagues demonstrated in PLoS ONE (volume 11, number 1; DOI 10.1371/ journal.pone.0144871) with scientific certainty that trimming the back toe nails just once has over a 90% chance of saving that poor itchy mouse. Unfortunately, this method does not work for lesion under the neck or on the sides of the body. NCB-AALAS member Ben Franco modified a common 50mL conical tube and converted it into a handy dandy mouse restrainer and was perfect for back toe nail trims. Visit the journal site for a video demonstration