Daphnia in Pharmacology Outreach to School-Age Children

Maria Fernandes1, Julie Keeble1, Zoe Gaffen2, Ann Pitcher2, Mark Gadd3, Ken Gadd3. 1Institute of Pharmaceutical Science, King's College London, London, UK, 2School of Biomedical and Health Sciences, King's College London, London, UK, 34Science, Salisbury, UK

Daphnia magna, a species of freshwater water flea, is widely used in ecotoxicity testing. It is simple to culture and cost effective. Daphnia can be easily obtained from aquatic shops. We have used the water fleas in pharmacology demonstrations for school children in various contexts.

The transparent bodies of Daphnia enable the clear visualisation of the heart using a standard bench top microscope at low magnification (maximum x10 required). This makes it a useful preparation for the study of heart rate changes in response to various compounds and a good introduction to ‘in vivo’ pharmacology for school pupils.

Recently, a ‘Drug Discovery’ day was held at King’s College London in collaboration with the BPS where Daphnia were used to look at the ‘in vivo’ properties of a nitric oxide donor (sodium nitroprusside; 50 μM) for the treatment of hypertension. More recently, this preparation has been used by King’s in collaboration with GlaxoSmithKline in their educational programme, Scientists in Sport1, to determine the cardiovascular effects of drugs that are banned in sport, including adrenaline (100 μM) and the β-blocker, propranolol (1 mM). This approach has been used within multiple universities, Big Bang fairs and Cheltenham Science festival.

Students were given one Daphnia to put in a concave slide and view on their microscope. They were instructed as to how to locate the heart. Resting heart rates were taken for fifteen seconds and then multiplied to give beats per minute. The students then used plastic Pasteur pipettes to drop up to 3 drops of drug of interest onto the coverslip. 3 minutes thereafter, students took the heart rate as before, and noted the change in heart rate. The effect of sodium nitroprusside or propranolol was enhanced with pre-treatment of Daphnia with adrenaline.

Feedback from students strongly suggested that they enjoyed the practical. Students who were hesitant to participate were affected by the use of a live organism, prompting an ethical discussion on the treatment of the Daphnia. This practical is considered highly interactive and is of low cost and efficient to run.

In conclusion, the Daphnia heart rate practical is a very simple way to bring pharmacology to school pupils. It enabled us to demonstrate the effects of various widely known compounds on heart rate, one of the simplest cardiovascular parameters to measure and understand. We easily and successfully demonstrated this ‘in vivo’ practical at minimal cost, and it was very well received by both school children and teachers, most of who were learning about pharmacology for the first time.

1 www.scientistsinsport.com