Instructions for Wildlife samples
Instructions for Gamefarm samples

Types of Samples

Hair Samples are easy to obtain, have simple storage requirements and can routinely produce excellent data. For these reasons the majority of the samples that we handle are hair. If you are pulling hair samples out of an animal, look for coarse hairs that are clean and hard to remove. For example, the white, tail hairs from white-tailed deer are a very reliable sample type. With a good hair sample, a person with good eyesight will be able to hold the hairs up to the light and clearly see root bulbs. Store hair samples dry in unwaxed paper envelopes.

Bone and Antler Samples can be a good source of DNA assuming that they have not decayed while they dried out. Collect samples by drilling into the core of the bone or antler to the full depth of a 3mm (1/8") drill bit. Don't burn the sample! The shavings can be collected in a paper envelope and stored dry.

Fresh Meat is very easy to work with, and will produce lots of DNA. However, meat samples deteriorate rapidly if not stored properly. To assess the quality of the sample, just take a whiff; if it smells rotten, it probably won't work. Store several cubic mm of meat in a 2 ml tube of ethanol, or dry it in the oven at low temperature.

Ear Tissue is as easy as meat to work with, but less prone to rotting. Some styles of ear tags require removal of a disk of ear material for insertion; this disk is an outstanding DNA sample. For small mammals clip a piece of ear tissue several mm square. Ear tissue can be stored dry or frozen, or immersed in ethanol.

Semen Straws are a well preserved, generous source of DNA, even when the count is too low for use in AI. Used straws can also yield adequate quantities of DNA, but please ask the AI technician not to push the plug all the way through. With used straws you will also need to send us a sample of the female that the straw was used on as she will have contaminated the straw; we need to know which data came from her. Store used straws dry.

Feathers and Avian Blood are some of the most reliable sources of DNA that we have handled. Both can be stored in ethanol or dry.

Mammalian Blood is also a good source of DNA, but it requires more processing in the lab which will be reflected in pricing. Make sure to thoroughly mix vacutainers after drawing blood, and keep samples in the fridge, or frozen if they won't be used for several months. Lay the tubes on their sides so that they don’t crack while freezing. Purple-top tubes (EDTA) are preferred.

Scat is more difficult to work with than many other types of samples, but can routinely yield results in mtDNA analyses of species identity and, with enough data replication and reduced success rates, provide reliable individual identifications. Please don't send us entire logs – a 2 ml volume of dry material will suffice for carnivore scats, or a half dozen pellets for cervids.

Sample Storage

The goal behind any sample storage strategy is to limit the damage done to DNA through the activity of enzymes that are naturally present in the sample or that are produced by growing microorganisms. Since these enzymes normally function in a liquid, aqueous (water-based) environment, three common strategies for sample storage are freezing, drying or immersion in liquids that inhibit enzyme activity.

Drying is the strategy used most often by our customers. Drying is particularly practical with minute quantities of tissue, such as the follicle material attached to the base of a hair. Drying can also be applied to larger-volume samples like scat, meat and blood, but care must be taken to ensure that degradation does not occur during the drying process. The most convenient way to store dry samples is in uncoated (breathable) paper envelopes.

To ensure that moisture from the environment does not reach your samples (e.g. during shipping), you may wish to place several tablespoons of desiccant in an extra envelope (or other breathable container) and then place all of the envelopes, including the one containing the desiccant, in a sealed plastic bag. Desiccant is available at low cost from craft stores and flower shops where it is sold for drying flowers.

There is no need to freeze samples that have been dried; they will be stored at room temperature once they reach the lab.

Freezing is an effective strategy for a wide variety of tissues. The main problem with freezing is that freeze-thaw cycles can be damaging, and degradation can be rapid, even with partial thawing. This means that temperatures well below freezing must be maintained in situations like power outages, and shipping.

If you freeze liquids, especially vacutainers, lay the tubes on their sides and leave plenty of airspace to prevent the container from cracking during freezing.

Ethanol is our preferred liquid storage medium. In long-term storage experiments, we have had much better preservation of DNA with ethanol than with other solutions like salt-saturated DMSO. We have had excellent results with almost all types of samples stored in ethanol, including scat and avian blood.

Samples stored in ethanol should be no more than a few mm thick, and should be kept in screw-top vials (~2 ml volume is good) with a good rubber seal. Use good quality vials because the samples will not be preserved if the ethanol leaks out. The final concentration of ethanol should be 70% to 95%. By keeping the volumes low there will be fewer problems associated with shipping this flammable liquid.

Vacutainers are a good way to collect blood samples. Please mix thoroughly to prevent clotting, and store cool or frozen (taking care to prevent tubes from cracking during freezing).

Contamination with Human DNA

Unless your study species is a primate, the microsatellite markers that we use will not work on human DNA. If you are working on a primate then we have run enough human samples to be able to recognize when contamination with human DNA is taking place. While gender-determination markers are more prone to giving false results due to contamination with human DNA, we have put a major effort into developing markers that do not work on humans, and have tested those markers to make sure that they do not work on our own DNA. In short, we do not feel that it is necessary to wear gloves or a face mask while handling samples.