This is the first research by using suppression subtractive hybridization (SSH) to analysis the gene expression in marine macroalga Ulva fasciata Delile against excess copper toxicity, and it gives us a comprehensive understanding of the tolerant mechanism while macroalgae face to the excess copper. Suppression subtractive hybridization was used to identify genes differentially expressed following exposure to 50 £gM CuSO4 for 6- 12h in a marine macroalga Ulva fasciata Delile. In this work, 69 genes were identified, of which 55 were up-regulated and 14 were down-regulated. According to the database of Gene Ontology (GO), these genes were classified into 10 categories as follows: 1. Transcription; 2. Translation, ribosomal structure and biogenesis; 3. Posttranslational modification, protein turnover, chaperones; 4. Photosynthesis; 5. Cell redox homeostasis; 6. Stress; 7. Metabolism; 8. Energy production and conversion; 9. Transport; 10. Function unknown. According to the results, we suggest that the responses of U. fasciata against excess copper toxicity are mainly through increase of the energy production for providing sufficient energy to many metabolic pathways, and control of the Fe homeostasis and redox form of thiol groups for maintaining the cellular redox homeostasis, moreover, expression of photosynthetic genes for letting the photosynthesis work. In addition, to scavenge the ROS is by expression of stress-related genes, meanwhile, the proteins, DNA and lipids damaged by ROS (reactive oxygen species) and copper are repaired by expression of the other categorical genes. Over and above, the genes expressing in the metabolism category might maintain the amino acids homeostasis and increase the purine content, and subsequently increase the tolerant capacity of U. fasciata against excess copper toxicity. In addition, the concentrations of antioxidants and the activities and gene expression of antioxidant enzymes were determined in Ulva fasciata Delile by a 4-day exposure to 0, 5, 10, 20 and 50 £gM CuSO4. These results demonstrate that the maintenance of antioxidant homeostasis and the induction of activities of antioxidant enzymes via enhanced gene expression are used by U. fasciata to cope with the Cu-induced oxidative stress, but the defense capacity cannot sufficiently alleviate oxidative damage occurring under the condition of higher Cu concentrations. Moreover, according to the results from the expression of genes involved in the control of redox homeostasis and antioxidant defense was studied in macroalga Ulva fasciata Delile in response to CuSO4 (5 and 50 £gM) and ROS (H2O2 and O2£»-), we suggest that ROS involved in up-regulation of antioxidant defense-related genes and the expression of genes of antioxidant defense enzymes and UfMsrA (methionine sulfoxide reductase A) are associated with long-term adaptation of U. fasciata to Cu excess and transcription of redox- related genes and UfGr (glutathione reductase) is up-regulated for short-term acclimation. Promoters play a key role in regulating gene expression. Based on the analysis of cis-acting elements on UfMsr promoters, we suggested that the signal transduction pathway of copper stress in U. fasciata is related to that of other stresses and of defense-related plant hormones, however, Ca2+ and calmodulin might participate in it. To sum up, U. fasciata could resist oxidative damage caused by excessive copper through the regulation on the molecular level.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-1228109-120140 |
| Date | 28 December 2009 |
| Creators | Wu, Tsung-meng |
| Contributors | Hao-Jen Huang, Zin-Huang Liu, Kuo-Chen Yeh, Ming-Tsair Chan, Yi-Ting Hsu, Tse-Min Lee, Ching-Huei Kao |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-1228109-120140 |
| Rights | off_campus_withheld, Copyright information available at source archive |
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