Teresa Zavanella

Natural variation in the limb skeletal pattern of the crested newt, Triturus carnifex (amphibia: Salamandridae)

The forelimb skeletal patterns of two geographically isolated populations of Triturus carnifex, one from northern Italy (Rosate, Milano) and one from central Italy (Bagnaia, Perugia) were studied. A total of 1,018 limbs were examined. Limb skeletal variants, generally consisting either of a reduced number of carpals and/or of an alternate phalangeal formula, were commonly observed, as has been reported for other amphibian species. The population from northern Italy showed a greater variability than that from central Italy. Skeletal variants were present in 34% and 12% of the limbs, respectively (i.e., in 48% and 20% of the newts). In the Rosate population, the majority of variants consisted of fusions of radiale and prepollicis and of the phalangeal formula 1‐2‐3‐2. Severe skeletal defects were also found in 3% of the limbs of the newts from Rosate and in 1% of the limbs of those from Bagnaia. At present, no conclusion can be drawn about the evolutionary significance of the limb skeletal variation observed in the two populations, because of the paucity of data on intra‐ and interpopulation variations in other species of the genus Triturus.

Abnormal limb regeneration in adult newts exposed to the fungicide maneb 80. A histological study

The effects of the fungicide Maneb 80 (manganese ethylenebisdithiocarbamate, 80% active ingredient) on the regenerating limb of the adult crested newt, Triturus cristatus carnifex, was studied. Female newts were exposed percutaneously to 5 ppm Maneb 80. One group of control newts was exposed to the inert ingredients of Maneb 80 (sodium lignin sulfonate and n-butylnaphthalene sulfonate), and another control group was kept in tap water. The limbs were examined histologically at weekly intervals throughout the regeneration period and at the end of the experiment (10-12 wk postamputation). The regenerating limbs of all the animals exposed to Maneb 80 showed growth retardation and skeletal abnormalities. Histological examination provided evidence that vascular disturbances are important for the genesis of the developmental abnormalities induced by Maneb 80. The inert ingredients had a promoting effect on limb growth and had no teratogenic effects under our experimental conditions. There were no histological differences between the two control groups.

Age-related cell proliferation and apoptosis in the kidney of male Fischer 344 rats with observations on a spontaneous tubular cell adenoma

Cell proliferation rate and apoptosis were examined in archival kidneys from young, middle-aged, and old male F344 rats. Immunohistochemical expression of proliferating cell nuclear antigen (PCNA) and apoptosis were quantified in the same cell populations of the proximal tubule epithelium. A total of 79 kidneys from 40 rats were examined. There was a progressive increase in cell proliferation rates in rats from 4 and 6-10 months of age. In 23-month-old rats, proliferative activity appeared to be reduced. No age-related variations in apoptotic indices were found. One of the 16 rats aged 23 months had a tubular cell adenoma. In the tumor-affected kidney, cell proliferation rate was dramatically higher than in the contralateral kidney as well as in all the other kidneys examined. This high proliferative activity was not balanced by variation in cell death.

The toxicity of manganese ethylenebisdithiocarbamate to the adult newt, Triturus cristatus.

SummaryThe toxicity of ethylenebisdithiocarbamate (maneb), a widely used agricultural fungicide, to the adult newt (Triturus cristatus carnifex) was evaluated after percutaneous exposure. Maneb was lethal to all the animals at the 50 ppm level within fifteen days. Male newts seem to be less resistant to the toxicant than females. At concentrations as low as 25 ppm all males died within 25 days, whereas some of the females were still alive after 5 months. Microscopic examination showed that the skin and the kidney were the most severely affected organs. It has been hypothesized that an osmoregulatory breakdown and an impairment of cutaneous respiratory exchanges play a role in the death of the animals. Renal failure must also be taken into account. However, additional mechanisms can not be ruled out at present.

Environmental temperature and metastatic spread of melanoma in the crested newt

The influence of environmental temperature on tumor growth in newts injected subcutaneously with melanoma cell suspensions was studied. No signs of tumor growth were observed in animals kept at 4 degrees C, even after 1 year, whereas animals kept at 30 degrees C died after 2-4 weeks of widespread metastatic disease. In newts kept at both 17 degrees C and 27 degrees C and killed 25 days after the tumor grafting, blood-borne tumor emboli were often found. However, widespread metastases were present only in those kept at 27 degrees C. These findings suggest that by operating at a proper environmental temperature to slow down tumor growth, melanoma of the crested newt could serve as a useful experimental model for study of the different steps of metastatic spread.

Tumor-initiating activity of the beta-blocker ZAMI 1305 in the liver of the female Wistar rat.

A 1-week treatment with the hepatocarcinogen beta-blocker DL-1-(2-nitro-3-methyl-phenoxy)-3-tert-butylamino-propan-2-ol (ZAMI 1305) induces the appearance of preneoplastic liver lesions--oval cell hyperplasia, basophilic and gamma-glutamyltranspeptidase positive (GGT+) foci--in female Wistar rats, as evidenced by the Solt and Farber short-term test of carcinogenesis. ZAMI 1305-treatment also induces liver DNA damage, as evaluated by alkaline sucrose gradient analysis. The data suggest that the oncogenic B-blocker ZAMI 1305 has initiating activity in the liver of the female Wistar rat.

Toxicity of 2-methyl-4-chlorophenoxyacetic acid to the adult crested newt

The toxicity of the herbicide Agroxone 3, a commercial formulation of the sodium salt of 2-methyl-4-chlorophenoxyacetic acid (MCPA), in the adult newt (Triturus cristatus carnifex) was tested after percutaneous exposure. At the concentration of 3200 ppm, the LT50 values were 17 and 21 hr for male and female newts. At 1600 ppm, the LT50 values were 35 and 45.5 hr. At 800 ppm, most of the animals were still alive after the 3 months of experimentation. There were no deaths at 400 and 200 ppm. Severe neuromuscular disorders were observed in animals exposed to lethal concentrations.

SKIN DAMAGE IN ADULT AMPHIBIANS AFTER CHRONIC EXPOSURE TO ULTRAVIOLET RADIATION

Abstract— The effects of repeated UV exposure on the skin of the European crested newt, Triturus cristatus carnifex, have been investigated. The animals were irradiated 3 times per week with a Westing‐house FS40T12 fluorescent sun lamp (wavelength spectrum 275–350 nm). Two groups of animals received the same total fluence of 1.3 × 105 J/m2 in single fluences of either 1570 J/m2 (group A) or 9430 J/m2 (group C), and one group received a total fluence of 2.6 × 105 J/m2 in single fluences of 4710 J/m2 (group B). All the animals were killed 7 months after the first UV exposure, but at different intervals after the last exposure. Striking epidermal hyperplasia was found in the newts irradiated at the lower fluence rate (group A). In the animals given the higher total fluence (group B), the most prominent skin changes were dermal fibrosis and irregular thinning and thickening of the epidermis. No significant skin changes were found in group C., in which if there had been UV lesions, they had been repaired during the 5 month interval between the last irradiation and the killing of the animals. No skin tumors developed in any experimental group.

Teratological evaluation of the phenoxyacid herbicide MCPA in the regenerating forelimb of the adult newt

The effects of a commercial formulation of the phenoxyacid herbicide 2-methyl-4-chlorophenoxyacetic acid sodium salt (MCPA) on the regenerating forelimb of the adult crested newt were studied. The animals were exposed percutaneously to 0, 200, 400, or 800 ppm of MCPA for 4 days a week throughout the regeneration period and were sacrificed 11 weeks after amputation. The concentrations tested did not cause histologically detectable toxic lesions of the examined organs. Exposure to MCPA resulted in a significant retardation of the morphogenetic process as evidenced by skeletal examination. At the highest concentration tested, a significant growth delay was also evident during the regeneration period. No significant differences in the frequency of skeletal malformations were observed between control and treated newts, although the frequency was higher in the latter.

The toxicity of 2,4-dichlorophenoxyacetic acid to the adult crested newt

The toxicity of the herbicide Agroxone 5, a commercial formulation of the iso-octyl ester of 2,4-dichlorophenoxyacetic acid (2,4-D), in the adult crested newt (Triturus cristatus carnifex) was tested after percutaneous exposure. The compound was lethal to all the animals within 72 hr at concentrations of 100, 125, and 150 ppm. Males appeared to be more susceptible than females to the toxic effects of 2,4-D, since the LT50 values at 75 ppm were 102 and 132 hr for male and female newts, respectively. At 50 ppm, all the males died within 31 days of exposure, whereas the females were still alive at the end of the 3-month experiment. Only one male died at 25 ppm after 21 days. Vacuolar degeneration of liver parenchyma and necrosis of kidney tubules were found at lethal concentrations of 2,4-D. The severity of the lesions was related to the duration of exposure more than to the concentration of the herbicide.