REPAIR OF TISSUE AND DNA DAMAGE IN ZEBRAFISH EYES POST FRACTIONATED GAMMA IRRADIATION

• Main Author: Tetriana, Devita
• Format: Theses
• Language: Indonesia
• Subjects: Ilmu hayati ; Biologi
• Online Access: https://digilib.itb.ac.id/gdl/view/36184
• Institution: Institut Teknologi Bandung

Radiotherapy is one of the effective treatment in cancer therapy, utilizing ionizing radiation sources, such as gamma rays, which have great energy that can penetrate body tissues. The radiation dose to the radiotherapy is given in stages, and called fractionation. Effect of fractionation dose radiation therapy with the ability of normal cells to repair the damage, has not been used in the cancer treatment Therefore, we conducted a study to investigate the repair of tissue damage DNA damage. In this study, the eyes were as a model of normal cells and zebrafish were used as an animal model. Zebrafish treated with fractionated gamma radiation as much as one to five times, at a dose of 2 Gy and the dose rate 231.20 Gy / h was given once a day . Parameters measured were repair in the retinal tissue through histological preparations with HE staining, repairing of DNA damage was evaluated by analysis the profile of DNA fragmentation using the TUNEL assay with Image-J and analysis of gadd45, rad51, and xrcc6 gene relative expression profile in zebrafish eyes with qPCR method. The evaluation gene expression was gadd45 genes induced by the presence of DNA damage as well as the relative expression of DNA repair gene rad51 and xrcc6. Observations were made one and seven days post fractionated gamma irradiation. On histological evaluation shows that at one day after fractionated irradiation any changes in the eye's retina layer structure characterized by reduced density of cells in the lining of the retina, especially the retinal pigmented epithelium layer (RPE) and the outer nuclear layer (ONL). Seven days post-fractionated irradiation, there was an increase in cell density and there were grouped cells in ONL layer retinal tissue, that that were suspected as proliferate cells and will replace the damaged cells. This was thought to occur because of the regeneration of cells to repair tissue damaged by radiation. This suggests that tissue repair may occur within seven days. One day post-fractionated irradiation, the highest number of DNA fragmentation was occurred in three times fractionation as many as 480 cells and then fell until 167 cells in five times fractionation. This was thought to occur because of the repair response of cells exposed to radiation. Seven days post-fractionated irradiation, the number of cells with DNA fragmentation decreased, was expected to have occurred a DNA repairing process. The increasing frequency of fractination the higher gadd45 gene relative expression, which indicates that the higher protection level to DNA damage. The highest upregulation expression of rad51 gene occurred on seven days post twice fractionated irradiation, with the value of the relative frequency of 5.427 times higher than the expression of the control. xrcc6 expression was highest at one day post-four times fractionated irradiation, with the value of the relative expression was 4.756 times higher than the expression of the control. This suggests that DNA repair processes may occur within one day. Differences in the pattern of relative expression of DNA repair genes, rad51 and xrcc6, indicated associated with the cell cycle in which both genes were working on different repair pathways. From the results of this study, it could be concluded that repair damage to the ONL layer retina of the eye of zebrafish occur through the process of cell regeneration in seven days. rad51 and xrcc6 gene plays a role in DNA damage repair zebrafish eyes, where the relative expression of genes xrcc6 more dominant, and the DNA repair process occur within one day.