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03/28/2017 HYU News > Academics


Impact of Nickel on Frog Embryos

Gye Myung-chan (Department of Life Science)


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Environmental pollution permeates many lives of animals and humans and lowers the quality of life due to causes that consist of not only diseases but surprisingly of malformations as well. Professor Gye Myung-chan of the Department of Life Science specializes in the embryology of mammals and amphibians, and the harmful effects of environmental pollutants, such as heavy metals and endocrine-disrupting chemicals (EDC). Graduated from both HYU and its graduate school, he was given many awards and president of various academic societies, such as Korean Society of Environmental Biology. His recently published paper called “Nickel affects gill and muscle development in oriental fire-bellied toad (Bombina orientalis) embryo” observes nickel’s adverse influence to frog’s embryos.
Gye is interested in embryology, which is a field of study that observes the early stages of life including the formation of sperm, ovum, and embryo.

Even though amphibians include most endangered animals compared to other species, there is not enough research about frogs. This situation applies to studies about how organisms are affected by environmental pollutants occurred by artificial causes, such as nickel and other heavy metals, which is being researched by a lot of scholars.
Searching for his own domain of studies, Gye decided to conduct an experiment regarding how nickel can negatively affect Bombina orientalis, a common widespread frog that lives in Korea. Due to its mild disposition, big and thus easily observable eggs, and the small body size being the advantage of handling with ease, the frog was chosen for the subject of Gye’s studies. “I also wanted to show that Korean frogs can be used as an important biological resource.” Gye included.
To begin with, Gye let the frog’s embryos grow in multiple amount of nickel for 168 hours and found out the sublethal and lethal concentrations of the substance. “Sublethal concentration, which is about 1~10 uM (the 1,000,000/1 of 1 mole) is where embryos survive to display various abnormalities, such as underdevelopment of gills, tail dysplasia, bent trunk, and abdominal blister. On the other hand, lethal concentration, approximately 100 uM, is where death of embryos disenable the observation of their malformation,” said Gye.
Various deformations of tadpoles under sublethal nickel concentration.
(Photo courtesy of Gye)

The period where the embryos were most sensitive to nickel was the ‘pre-muscular response to muscular response stages’. These stages are when the embryos develop to use their muscles to make their tail move. “Like the thalidomide incident where the babies of women who take doses of the medicine to reduce nausea in the early stage of their pregnancy became deformed, there is a much more sensitive period of certain substance’s adverse effects, ” explained Gye.
The deformation of the embryo's tail during ‘pre-muscular response to muscular response stages’. The stage is where the tadpole starts to move its tail using its muscles.
(Photo courtesy of Gye)

Seeing that the tadpoles displayed signs of deformations, especially the abnormality of tail muscles, he cloned their DNA that controls the development of the muscles to find out the exact causes for the malformations. “DNA transcripts RNA, and it makes proteins. Proteins that are needed for composing muscles is then selectively turned on by hormones. Next, the signals of the hormones are caught by the transcription factors that help produce RNA,” Gye described. Then, he discovered that nickel prevented the activation of the transcription factors such as myogenic regulatory factor 4 mRNA, thus inhibiting the development of muscle proteins.
Gye also found out that exogenous calcium reacts oppositely to nickel’s adverse effects. “The composition of calcium is similar to that of nickel. They compete against each other and then calcium replaces nickel, “ Gye mentioned. Gye found out that calcium’s substitution of nickel restores some of its negative effects to the embryos by re-increasing protein levels and calcium-dependent kinase activities, which has the role of changing the structures of proteins.
“The dangers of nickel and other heavy metals apply not only to frog embryos, but also to other species and humans. The only solution to the problem is to reduce and prevent the spills of nickel caused by mining and industrial production, and law enforcement that regulates the spills is necessary,” Gye explained. Greatly interested in environment and the humans that live in it, Gye is currently leading the Enterprise Organization for Development of Alternative Chemicals of EDC of the Ministry of Science, ITC, and Future Planning. “I hope, through my research that I could realize Hanyang’s founding philosophy, Love in Deed, by enabling people to live healthier. I wish I could benefit the society by conducting useful and practical research,” Gye said.  
"I want to realize the founding philosophy of Hanyang by heightening the quality of life through my research."

Jang Soo-hyun
Photos by Choi Min-ju
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