Effects of light on hamster activity patterns

 This experiment is a synopsis of an article by J. Cheverton and F. Ebling (1997).  For additional information and complete instructions, please refer to:

 Cheverton, J. and Ebling, F.  (1997) "Datalogging hamster activity rhythms", Journal of Biological Education, 31,11-16.

 Background:

            Eukaryotic organisms have internal timing mechanisms that regulate physiological, morphological, and behavioral adaptations in response to changes in surrounding environment.  Daily behavioral activity patterns are synchronized by the organism’s light and dark cycles (Moore, 1992; Chadwick and Ackrill, 1995). 

 Materials:

            The recommended experimental subject is a young (2-3 months) male Dwarf Russian (Phodopus sungorus) or Golden (Mesocricetus auratus) hamster.  Experimental trials should be conducted in a series of connected hamster cages that are large enough to hold food and water for 3 days and an appropriately sized exercise wheel.  Attach a datalogger® to the wheel that will record each activity session as one event and the time of the activity.  Place the subject and cage with sufficient food and water in a controlled light room with no natural light; then set up a dim red light (photographer’s safe light) and a white light on timed switches to control the photoperiod.  

 Methods:

            Trial 1 - Set the white light and the red light to shine alternately for 12 hour periods.  Expose the subject to this 12 hour light and dark schedule for at least 72 hours.  Do not disturb the subject except to check on food and water status.  Make sure that the data logger is recording activity events.

            Trial 2 - Set the red light to 24 hours and zero hours for the white light.  Expose the subject to this photoperiod for at least 72 hours.

            Trial 3 - The results of trials 1 and 2 should suggest a strong internal clock which regulates most activity to nocturnal periods.  This internal clock can be altered by small changes in light cues.  Set the red light to 23 hours and white light to one hour after the onset of normal nocturnal activity.  Over a period of time on this schedule, the initiation of activity should begin to initiate at an earlier time.  Once the subject has adapted to the earlier activity period, the light period can be set ahead an additional hour which should cause the subject to initiate activity earlier.  This alteration of behavior in response to light can be used to show how organisms respond to environmental cues.

 Refer to Cheverton and Ebling (1997) for additional trials. 

 Literature Cited:

 Chadwick, D. J. and Ackrill, K.  (1995) Circadian clocks and their adjustment.  Ciba Foundation Symposium 183.  Chichester, W. Sussex:  John Wiley & Sons.   

Suppliers:

The DL+ Datalogger® and Datadisk® software is available from Philip Harris Education, Lynn Lane, Shenstone, Lichfield, Staffs.  WS14 0EE. Tel: 01543-480068.

'Sense and Control'® equipment is available from Data Harvest, Wooburn Lodge, Waterloo Rd, Linslade, Leighton Buzzzard, Beds. LU7 7NR.  Tel: 01525-373666.