博士 / 國立中山大學 / 海洋生物研究所 / 101 / The aim of this study was to determine the lens crystallin diversity of fishes living in varied environmental habitats under different light conditions. We employed state-of-the-art proteomics methodologies to investigate proteomic change associated with the evolution of fish lenses particularly concerning the functional loss of lenses in eyes of fishes living under an environment of perpetual darkness.
The experiments were divided into three parts: the first part is to analyze the degenerative eye lenses of nocturnal rice eel and catfish as compared to diurnal zebrafish; the second part is to analyze and compare the different electrophoretic protein spots of albino-type fish (Corydoras aeneus var.) and wild-type fish (Corydoras aeneus); the third part is to analyze the crystallin distribution in the eye lenses of ten piscine species from epipelagic to bathypelagic environments.
Fish lenses were collected and homogenized to extract total soluble proteins. The protein mixtures were separated by one- and two-dimensional gel electrophoresis (1-D or 2-D gel), samples of the first-part study were analyzed by the newer gel-free shotgun proteomic strategy, followed by in-gel digestion and the digested protein bands or spots subjected to liquid chromatography coupled with tandem mass spectrometry. The proteomics data were analyzed and compared based on the proteomics databank of zebrafish. The validation and comparison of various crystallin families, e.g., α-, β-, and γ-crystallins were based on 1-D and 2-D sodium dodecyl sulfate–polyacrylamide gel electrophoresis.
In rice eel’s lenses, β- and γ-crystallins comprised more than 98% of total lens proteins whereas very little or almost no α-crystallin was detected. It was of interest to note that α-crystallin showing obvious differences in protein contents between the nocturnal fishes of rice eel and catfish in spite of the similarity in their living habitat.
For the wild type and albino mutant of Corydoras aeneus’s eye lenses, it was found that the crystallin content is very similar between the two. However the 2-D gel show that α-crystallin region of Corydoras aeneus lenses containing 3 protein spots, which was different from that of Corydoras aeneus var. lenses containing 6 spots.
For experiments on lens protein variation in fishes from environments of different light exposure such as fishes living in the epipelagic, mesopelagic and bathypelagic zones, the content of α-crystallin decreased, and γ-crystallin increased with the ocean depths of piscine living habitats.
The total numbers of α-, β-, and γ-crystallins in the piscine species examined by the current proteomics methodology clearly indicate the complexity and diversity of crystallin species present in different fish species. It is noteworthy that only small amount of α-crystallin was present in the degenerative eye lenses of rice eel and bathydemersal fish species (i.e., Lophiomus setigerus), which points to the fact that this crystallin acting as a chaperone protein may be essential in vertebrate species to protect lens proteins from aggregation and to maintain functional transparency of the lens under varied environmental conditions. A detailed study on the correlation between the chaperone function and lens development warrants future investigation.
| Identifer | oai:union.ndltd.org:TW/101NSYS5270017 |
| Date | January 2013 |
| Creators | Yi-Reng Lin, 林怡礽 |
| Contributors | Hin-Kiu Mok, Shyh-Horng Chiou, 莫顯蕎, 邱式鴻 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 210 |
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