Abstract
Model fish species such as sticklebacks and zebrafish are frequently used in studies that require DNA to be collected from live animals. This is typically achieved by fin clipping, a procedure that is simple and reliable to perform but that can harm fish. An alternative procedure to sample DNA involves swabbing the skin to collect mucus and epithelial cells. Although swabbing appears to be less invasive than fin clipping, it still requires fish to be netted, held in air and handled—procedures that can cause stress. In this study we combine behavioural and physiological analyses to investigate changes in gene expression, behaviour and welfare after fin clipping and swabbing. Swabbing led to a smaller change in cortisol release and behaviour on the first day of analysis compared to fin clipping. It also led to less variability in data suggesting that fewer animals need to be measured after using this technique. However, swabbing triggered some longer term changes in zebrafish behaviour suggesting a delayed response to sample collection. Skin swabbing does not require the use of anaesthetics and triggers fewer changes in behaviour and physiology than fin clipping. It is therefore a more refined technique for DNA collection with the potential to improve fish health and welfare.
Highlights
Changes to the health and welfare of animals can alter their behaviour and p hysiology[1]
We measured changes in gene expression, behaviour and condition indicators at various time points after manipulation to investigate whether skin swabbing represents a less invasive method of collecting DNA from live fish than fin clipping
Groups of sticklebacks treated with MS-222 displayed reduced opercular beat rate (OBR) compared to the other manipulations, suggesting that immersion in anaesthetic decreased ventilation (Fig. 1a)
Summary
Changes to the health and welfare of animals can alter their behaviour and p hysiology[1]. The initial stress of netting a fish and exposing it to air can cause elevated cortisol levels[23,24], and zebrafish actively avoid exposure to anaesthetics such as MS-222 and benzocaine[25] which can trigger stress responses[26] Since such changes can dramatically affect the quality of experimental data[5], efforts to improve and refine techniques for DNA collection have increased[27,28]. Developing an alternative to fin clipping will benefit the health and welfare of fish but may improve the reliability, and the repeatability, of scientific data c ollected[29] with the potential to reduce the number of animals used
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