Recently, in order to advance biological technology and increase the number of elite dogs that possess unique abilities, researchers have put more focus on cloning superior dogs that have been acknowledged in their respective fields. These experiments depend on the known fact that cloned dogs will be both physically and psychologically similar to those that provided the somatic cells. However, little research has focused on whether it is genetic or posteriori factors that influence abilities to accomplish tasks. In this experiment, cloned beagles that have been produced from one somatic cell and thus have the same genetic information were tested on learning and memory behaviours. This experiment was performed to investigate the similarity in behavioural patterns between these cloned individuals (n = 6). A Y-maze test, which is commonly applied for evaluating learning and memory, was performed using 12 Beagles, 6 of which were cloned dogs and the other 6 were naturally bred controls (n = 6). One snack was placed at the end of each arm of the Y-maze. The snack that was placed in the east arm was accessible to the dogs, whereas the other was blocked using a plastic fence. All 12 dogs were trained before the experiment, where they were sent through the maze 10 times and allowed to obtain the snack. Following this training period, the dogs were retested 3 times to assess learning and working memory. The first trial (Day 0) was performed 1 day after the training period, while the second (Day 7) and third (Day 14) trials were performed at 1-week intervals. In each trial, the dog was given 60 s to make a choice between the east or west arm of the Y-maze. If correct, the dog received a feed reward. After consuming the reward, the dog was picked up by the experimenter and placed outside in preparation for the next dog. In every trial, each dog was sent through the Y-maze 5 times. Using the Harvard Panlab software and a live video image, the latency to choice was measured. All cloned dogs reached the performance criterion with 100% correction on Day 0 of acquisition. However, all naturally bred dogs reached the performance criterion (85% correction) at a lower rate than those of cloned dogs. Correct choices were maintained in all experimental dogs during re-assessment time. Mean latency to choice showed no significant differences between naturally bred controls and cloned dogs. Interestingly, when the standard deviation (s.d.) of the latency to reach the target was compared, the s.d. within the cloned group was significantly lower than that within the control group only on the first assessment (Day 0). However, no significant differences were shown during the second (Day 7) and third (Day 14) trials. Therefore, it appears that genetically identical cloned dogs do not show greater consistency in their learning and memory behaviour than litters of naturally bred control dogs. The learning and memory ability of cloned dogs were not different from those of naturally bred control dogs.
This research was supported by the SNU Undergraduate Research Program.
Academic and Professional Preparedness: Outcomes of Undergraduate Research in the Humanities, Arts, and Social Sciences
