The Developmental Effects of the Time and Duration of Exposure on Xenopus laevis Embryos by Sodium Selenate
Date
2-14-2024
Faculty Mentor
James Rayburn, Biology
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Submission Type
Conference Proceeding
Location
8:15-8:25am | Houston Cole Library, 11th Floor
Description
Amphibians play critical roles in the environment's wellbeing. Selenium (Se) can be found in organic and inorganic forms in nature. Many different fertilizers, pesticides, insecticides, and fungicides have sodium selenate in them. The range selenium has between deficiency and toxicity is narrow, meaning excess exposure could cause various adverse effects in aquatic organisms. From previous experiments using Xenopus laevis embryos with sodium selenate after a 4-day exposure to 100 mg/L concentration had a 100% mortality rate that occurred at day 4. Xenopus laevis is a standard model for developmental toxicity due to being minimal maintenance, cost efficient, and having transparent embryos. The observation of mortality occurring suddenly on day 4 of the experiment lead to the question of why, was it accumulation of sodium selenate or possibly related to developmental stage. The objective in this study is to determine if accumulated exposure to sodium selenate or developmental timing was most important in explaining why mortality did not occur till day 4. This was investigated by exposing 4 petri dishes of 20 embryos each to 8 mls of 100 mg/L. Each set of 4 petri dishes contained either 100 mg/L Se and were exposed to 7 various times and exposure lengths and 1 set of negative controls. A single experiment used a total of 640 embryos. The experiment was repeated three times for a total of 1,920 embryos. For each experiment a different pair of frogs were used to account for genetic variation. Mortalities were counted for each day. Mortalities and malformations were counted on the last day of the assay and embryo length were measured. Results showed that embryos exposed for 48-96 hours perished. The time of development within the embryos that were exposed for 24 hours at a time played a role in mortality that occurred. Embryos that were exposed for 24 hours between days 2-3 and 3-4 were deceased and severely malformed. Malformations such as stunted growth, edemas, loose gut, hemorrhages, bent notochords, and kinked tails were seen throughout each experiment. Embryos that were exposed for 24 hours between days 0-1 and 1-2 barely showed any mortalities or malformations.
Overall, time of exposure / developmental stage seemed more important than duration for the developmental toxicity to Xenopus laevis. The sodium selenate impacted the embryos more at the 2-3;3-4 day exposure than the 0-1;1-2 day exposure. Future testing could pinpoint what part of the embryo is developing at certain times to determine what is being affected by the sodium selenate.
Keywords
student research, biology
Rights
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Disciplines
Biology
Recommended Citation
Wolfram, Shelby, "The Developmental Effects of the Time and Duration of Exposure on Xenopus laevis Embryos by Sodium Selenate" (2024). JSU Student Symposium 2024. 38.
https://digitalcommons.jsu.edu/ce_jsustudentsymp_2024/38