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Assessing the Quantity and Downstream Performance of DNA Isolated from Beluga (Delphinapterus leucas) Blow Samples
Abstract: Blow (exhale) sampling in cetaceans may provide a minimally invasive alternative to biopsy sampling for genetic analyses that may be favored in vulnerable populations. However, the utility of single-exhale blow samples has not been evaluated, and the relationship between the number of exhales collected and DNA yield and its subsequent performance during polymerase chain reaction (PCR) is unknown. DNA was extracted from 98 blow samples collected from 11 aquarium-housed and 29 wild belugas in Bristol Bay, Alaska. Blow samples consisted of one, two, or four successive exhales, with at least nine samples per type from both aquarium-housed and wild belugas. DNA concentration and purity was assessed with a spectrophotometer, and PCR performance was assessed through the amplification of a fragment of the mitochondrial DNA control region or a nuclear marker of sex. Measurable DNA was recovered from 96 samples (98%), although DNA yield varied widely, both by sample (range: 0 to 4,406 ng, mean = 701.5, SD = 1,033.7) and by number of exhalations (ng DNA/exhale) (range: 0 to 3,723, mean = 427.1, SD = 721.8). The amount of DNA extracted per exhale was greater for aquarium samples than for wild samples, but total yield was not proportional with the number of exhales for either group. Successful beluga-specific PCR amplification occurred in 56/59 of the aquarium samples (23/25 single-exhale samples) and 28/39 of the wild samples tested (7/10 of the single-exhale samples). The forcefulness of the breath and chance collection of large pieces of cellular debris likely shaped the relationship between the number of exhales and the DNA yield. Using these methods, a single, forceful exhale should yield enough DNA to perform multiple experiments. This technique is immediately applicable to live-stranded belugas such as the temporary mass strandings that occasionally occur in Cook Inlet, Alaska, and has the potential to increase genetic sampling in protected populations with less disturbance than direct tissue sampling.
Key Words: blow, exhale, respiratory vapor, genetic sampling, beluga, Delphinapterus leucas
Document Type: Research Article
Page Numbers: 398-408