Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
J Appl Toxicol
2023 Mar 01;433:431-445. doi: 10.1002/jat.4393.
Show Gene links
Show Anatomy links
Influence of systemic copper toxicity on early development and metamorphosis in Xenopus laevis.
Fort DJ
,
Todhunter KJ
,
Wolf JC
,
Long K
,
Poland CA
,
McGrath M
,
Baken S
,
Mackie C
.
???displayArticle.abstract???
The primary objective of the present study was to examine the influence of early systemic toxicity resulting from copper (Cu) exposure on metamorphic processes in Xenopus laevis. A 28-day exposure study with copper, initiated at developmental stage 10, was performed using test concentrations of 3.0, 9.0, 27.2, 82.5, and 250 μg Cu/L. The primary endpoints included mortality, developmental stage, embryo-larval malformation, behavioral effects, hindlimb length (HLL), growth (snout-vent length [SVL] and wet body weight), and histopathology. The 28-day LC50 value with 95% confidence intervals was 61.2 (51.4-72.9) μg Cu/L with 250 μg Cu/L resulting in complete lethality. Developmental arrest in the 82.5 and delay in the 27.2 μg Cu/L treatments was observed as early as study day 10 continuing throughout the remainder of exposure. SVL-normalized HLL, body weight, and SVL in the 27.2 and 82.5 μg Cu/L treatments were significantly decreased relative to control. At 82.5 μg Cu/L, and thyroid gland size was markedly reduced when compared with controls consistent with the stage of developmental and growth arrest. Concentration-dependent findings in the intestine, liver, gills, eyes, and pharyngeal mucosa were consistent with non-endocrine systemic toxicity. These were prevalent in the 9.0 and 27.2 μg Cu/L treatment groups but were minimally evident or absent in the 82.5 μg/L group, which was attributed to developmental arrest. In conclusion, developmental delay in larvae exposed to 27.2 and 82.5 μg Cu/L was the result of systemic toxicity occurring in early development prior hypothalomo-pituitary-thyroid axis (HPT)-driven metamorphosis and was not indicative of endocrine disruption.
FIGURE 1
Effects of 28-day Cu exposure initiated at Nieuwkoop and Faber stage 10 on survival in X. laevis. The 28-day LC50 with 95% confidence interval provided in text box.
Effects of 28-day Cu exposure on development and growth in X. laevis. From top to bottom: 0.00 (control), 3.0, 9.0, 27.2, and 82.5 μg Cu/L
FIGURE 3
Effect of copper on developmental stage in X. laevis tadpoles exposed for 28-day from NF stage 10. Note in premetamorphic stages NF 45â53, the thyroid has developed, but plasma TH is low, and in prometamorphic stages NF 54â58, the thyroid is more active and plasma TH levels rise (Leloup & Buscagalia, 1977; Shi, 2000). Arrow denotes the beginning of developmental stage separation noting that it occurs during premetamorphosis, and most likely independent of the thyroid axis.
FIGURE 4
Effect of 28-day Cu exposure on hindlimb length (mm). Data points represent meanâ±âSEM. Gray coloration represents significant decreasing trend (JonckheereâTerpstra test, pâ=â0.0034).
FIGURE 5
Effect of 28-day Cu exposure on SVL-normalized hindlimb length. Data points represent meanâ±âSEM. Gray coloration represents significant decreasing trend (JonckheereâTerpstra test, pâ=â0.0034).
FIGURE 6
Effect of 28-day Cu exposure on SVL. Data points represent meanâ±âSEM. Gray coloration represents significant decreasing trend (JonckheereâTerpstra test, pâ=â0.0162).
FIGURE 7
Effect of 28-day Cu exposure on wet body weight. Data points represent meanâ±âSEM. Gray coloration represents significant decreasing trend (JonckheereâTerpstra test, pâ=â0.0092).
FIGURE 8
(A) Thyroid from a control tadpole. (B) Thyroid from a tadpole exposed to 9.0 μg Cu/L. (C) Thyroid from a tadpole exposed to 27.2 mg Cu/L. (D) Left and right thyroids from a tadpole exposed to 82.5 μg Cu/L. (E) Eye from a control tadpole (aâ=âanterior chamber, câ=âcornea, lâ=âlens, pâ=âposterior chamber, râ=âretina). (F) Eye from a tadpole exposed to 27.2 μg Cu/L. AâD, barâ=â25âmm. EâF, barâ=â100âmm.
FIGURE 9
(A) Gill from a control tadpole. (B) Gill from a tadpole exposed to 27.2 mg Cu/L. (C) Liver from a control tadpole. (D) Liver from a tadpole exposed to 27.2 μg Cu/L. (E) Small (s) and large (l) intestines from a control tadpole. (F) Small (s) and large (l) intestines from a tadpole exposed to 27.2 μg Cu/L. AâD, barâ=â25âmm. EâF, barâ=â50âmm.
