Effects of overtraining on extinction in newts (Cynops pyrrhogaster).

Seasonal and geographical changes of spontaneous skin papillomas in the Japanese newt Cynops pyrrhogaster.

The occurrence of spontaneous skin papillomas in Japanese newts (Cynops pyrrhogaster) from Niigata prefecture in Northern Japan was monitored over four seasons covering a period of 2 years. Of 13,613 newts, 249 were found to possess papillomas. The percentage of newts with papillomas was highest in autumn, ranging from 1.93 to 5.45% of the total average. These values were more than four times a...

Imorin: a sexual attractiveness pheromone in female red-bellied newts (Cynops pyrrhogaster)

The male red-bellied newt (Cynops pyrrhogaster) approaches the female's cloaca prior to performing any courtship behaviour, as if he is using some released substance to gauge whether she is sexually receptive. Therefore, we investigated whether such a female sexual attractiveness pheromone exists. We found that a tripeptide with amino acid sequence Ala-Glu-Phe is secreted by the ciliary cells i...

Effects of overtraining on extinction in newts (

Induction of ocular tumor by nickel subsulfide in the Japanese common newt, Cynops pyrrhogaster.

Chemically induced ocular tumors in amphibians have not been reported previously. In the present study, nickel subsulfide (Ni3S2) was administered to lentectomized Japanese common newts, Cynops pyrrhogaster, by a single injection into the posterior chamber of the right eye (40-100 micrograms Ni3S2/newt). Control newts received a similar injection of vehicle. Malignant melanoma-like tumors devel...

Spontaneous epidermal tumor in an adult newt, Cynops pyrrhogaster.

Reports of spontaneous tumors occurring in urodele amphibians are rare (1-7, 9, 11, 13-15), and it has been suggested that animals that regenerate well, such as newts, retain powerful morphogenetic fields capable of controlling any aberrant cells that arise (8, 10, 12). It is certainly surprising that there are very few reports of spontaneous skin tumors in urodeles since, of all tumors, these ...