A while back, I wrote of my curiosity for genomics
, and understanding the hands-on aspects of collecting and analyzing DNA. I’d like to explore that topic in the next few posts, with this one focusing on collecting a hair sample, and subsequent posts following it through to the laboratory.
First observed in the late 1800s by Swiss biochemist Frederich Miescher, DNA (or deoxyribonucleic acid if you want to sound sciencey) is found in the nucleus and mitochondria of eukaryotic cells. It’s essentially the how-to manual for how an organism develops, survives and reproduces (though it’s generally a little more sophisticated than the instructions we get with unassembled furniture).
One of the most common ways to collect DNA in livestock production is through hair samples, which aren’t as easy to analyze as television dramas may have us believe.
Hair growth occurs in the follicle, formed by keratinocytes, which synthesize the protein keratin, one of the key structural components of hair. Over time, these cells die a ‘programmed death’ leading to the disappearance of their nuclei and cytoplasmic organelles. The hair shaft thus emerges from its protective bulb unliving. The process whereby the keratinocytes die and are converted from cells into tough, horny material is called cornification
In some instances keratinocytes may not complete differentiation, allowing fragments of nuclear DNA to be present in a sample. But in most cases, deriving DNA from a hair without its root is not possible.
For producers hoping to submit hair samples, most laboratories will provide guidelines similar to those outlined by the Beef Cattle Research Council’s blog
First, clean the tail switch to remove debris, then comb or brush to remove any dead hair. Wrap 5-10 strands around a finger and pull sharply against the direction of growth, inspecting to ensure the hairs have follicles attached (you should see tiny white/grey bulbs at the base of the hair). Once you’ve collected the necessary number, secure with tape roughly one inch from the follicles and place in a labeled envelope. Seal, wash hands and repeat.
Some laboratories will also accept DNA in the form of blood (either in a vile or on a special absorbent sheet), tissue or semen samples. I’ve chosen to talk about hair because of its surprising complexity, and its popularity in the Alberta-based Delta Genomics
Next week, we’ll look at where that sample ends up and how it’s analyzed.
Delta Genomics is the first DNA lab specializing in livestock in western Canada. Born of industry collaboration, the lab became an independent company in November of 2014.
Debra Murphy is a part-time farmhand and full-time field editor for RealAgriculture. She lives in Alberta, where she has never intentionally pulled hair from a cow. At least, not yet.