Effects of 2,4,6-Trinitrotoluene in a Holistic Environmental Exposure Regime on a Terrestrial Salamander, Ambystoma tigrinum

Abstract

ABSTRACT2,4,6-Trinitrotoluene (TNT) is a defense-related environmental contaminant present at high concentrations in soil at some military installations. Tiger salamanders (Ambystoma tigrinum, family Ambystomatidae) were exposed to TNT in a soil matrix and fed earthworms that had also been exposed to TNT via contaminated soil. Such exposure was previously shown to result in significant accumulation of both TNT and TNT metabolites by salamanders. Following 14 days of combined oral and dermal exposures, salamanders were evaluated for signs of toxicity. Control and TNT-exposed salamanders gained weight (p < 0.025). In addition, organ to body weight ratios (kidney, liver, and spleen) were not affected by treatment. The function of splenic phagocytic cells was evaluated because these cells are sensitive to certain environmental chemical exposures. Neither the chemiluminescence response (H 2 O 2 production) nor the phagocytic capacity of such cells were different between controls and treatment groups. In like manner, no changes were seen in the peripheral hematologic parameters investigated. Histopathologic evaluations were inconclusive, yet the liver revealed the presence of heavily pigmented iron-rich phagocytes (melanomacrophages). This investigation presents a realistic approach and preliminary data for investigating the effects of xenobiotic exposure in a soil matrix on a terrestrial vertebrate.

Evaluation of Two Methods for Measuring Nonspecific Immunity in Tiger Salamanders (Ambystoma Tigrinum)

“…Their methodology involved using supplemented RPMI medium and incubating cells at room temperature for 45 min. In contrast to findings by other researchers (Rosenkranz et al, 1992;Johnson et al, 2000), hydrogen peroxide production in our pilot studies was not enhanced by adding PMA. This lack of response may have been due to the use of thioglycollate to elicit the migration of neutrophils into the peritoneal cavity.…”

“…The mammalian assay was modified for use with amphibian cells by decreasing the incubation temperature from 37 to 27 C and changing the culture medium from phosphate-buffered saline with calcium and magnesium to APBS. Other published protocols (Rosenkranz et al, 1992;Johnson et al, 2000) recommend adding 0.1 nM-1.0 M phorbol 12-myristate 13-acetate (PMA; Sigma-Aldrich) to the culture medium to stimulate hydrogen peroxide production. In initial trials with cells from tiger salamanders stimulated with i.p.…”

Soils contaminated with explosives: Environmental fate and evaluation of state-of-the-art remediation processes (IUPAC Technical Report)

“…Skin was concluded to be important in the primary reduction of TNT. When salamanders were exposed to TNT in soil (1 mg/kg) and fed earthworms exposed to TNT in the same soil, no difference between control and treated animals were observed for weight gain, organ-to-body-weight ratios, function of spleenic phagocytic cells, nor peripheral hematological parameters [219]. However, the liver exhibited heavily pigmented iron-rich phagocytes (melanomacrophages) and growth rate was slower during treatment.…”

“…The salamander (Ambystoma tigrinum) has been suggested as a bioindicator of effects in the evaluation of toxicity of explosives at contaminated sites [217][218][219]. Dermal exposure was determined to be the most important exposure pathway for uptake of TNT from contaminated soil by the salamander.…”

Impact of Cadmium on Liver Pigmentary System of the Frog Rana ridibunda

“…Numerous studies suggest that MMCs are involved in scavenging of various catabolites and exogenous foreign material (Meseguer et al, 1994). Johnson et al (2000) concluded that MMCs in Ambystoma tigrinum may be associated with in#ammatory responses, including phagocytosis. Other researchers reported scavenging cytotoxic substances, such as ions and free radicals (Sichel, 1988;Zuasti et al, 1989).…”