Testing the applicability of tagging the Great crested newt (Triturus cristatus) using passive integrated transponders.

Tracking individual animals with small-sized passive integrated transponder tags (PIT tags) has become a popular and widespread method, one which can be used for investigating life history traits, including dispersal patterns of small protected animals such as newts. In this study, we tested the applicability of PIT tag usage for individual marking with the Great crested newt (Triturus cristatus) as a model amphibian species, and to test the detection of the newts in nature using a passive telemetry system. Clove oil was used as an anaesthetic before surgery. We implanted PIT tags under the skin of 140 newts. The survival rate of newts was 98.57%. X-ray images were taken to check the exact positions of the PIT tags. Since approximately 15.71% of the newts were capable of expelling the tag from their bodies, tag loss has to be accounted for in future behavioural studies dealing with newts and other amphibians potentially capable of frequent tag expulsion. Lastly, we detected by passive telemetry 97 individuals out of 100 released into a natural breeding pond. Males had higher activity (13 detected males vs 7 females per hour) than females, thus males could be detected if present with more certainty. The result of the movement behaviour showed that e.g. the male of T. cristatus in a breeding pond can travel up to 20 m in 78 seconds. In summary, this promising method could allow the automatic data collection of marked newts in aquatic as well as in terrestrial biotopes, providing data on their dispersal, diurnal activity and movement behaviour.

Analysis of morphogenetic potential of caudal spinal cord in Triturus carnifex adults (Urodele amphibians) subjected to repeated tail amputations.

The present research was aimed at testing whether the extraordinary morphogenetic and histogenetic potential exhibited in the regenerating new tail remains constant even after repeated amputation or whether it changes as a result of the mechanisms responsible for the regenerative process. Particular attention was focused on regeneration of the spinal cord and ganglia. For this purpose, tail regeneration in adult specimens of Triturus carnifex subjected to repeated amputation (up to 7 times) was compared with that of control animals subjected to a single amputation. Results show that although it slowed down the morphogenetic and differentiative phase, repeated amputation did not significantly alter either the morphogenetic or the histogenetic potential of the ependymal layer of the regenerating spinal cord. The latter result leads to hypothesized that the cells of the ependymal layer of the stump, which are responsible for the formation of the apical ampulla and the ependymal tubule inside the regenerative blastema, do not derive from undifferentiated reserve elements triggered after tail amputation but rather from differentiated ependymal elements that dedifferentiate after the trauma and re-acquire embryonic potential. If this regeneration were actually to take place at the expense of the reserve elements, the continual regenerative processes induced by the repeated amputation would lead to the increasing depletion of these elements and a consequent reduction in regenerative capacity.