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The isolation of retinal outer segment fragments
Abstract:
Bovine retinal outer segment fragments were isolated by density gradient centrifugation in a high centrifugal field. Assays of the final preparation for enzymes of the mitochondrial respiratory chain indicated mitochondrial contamination not in excess of 1 per cent. Glucose-6-phosphatase and TPNH-cytochrome c reductase activities, presumably diagnostic for microsomes, were also absent. Electron micrographs did not disclose the presence of significant numbers of particles other than fragments of the outer segment discs. The red fragments were characterized by an ascorbate-oxidizing system and a high lipid content.
Insights
Researchers isolated bovine retinal outer segment fragments using density gradient centrifugation. The purified preparation showed minimal mitochondrial or microsomal contamination, confirming its suitability for further biochemical studies.
Area of Science:
- Biochemistry
- Cell Biology
- Ophthalmology
Background:
- Bovine retinal outer segments are crucial for visual phototransduction.
- Accurate isolation of outer segments is essential for studying their biochemical properties.
- Previous isolation methods may have suffered from significant contamination.
Purpose of the Study:
- To isolate highly purified bovine retinal outer segment fragments.
- To assess and minimize contamination from other cellular organelles.
- To characterize the biochemical properties of the isolated fragments.
Main Methods:
- Isolation of bovine retinal outer segments via density gradient centrifugation.
- Enzyme assays to quantify mitochondrial respiratory chain contamination.
- Assays for microsomal markers (Glucose-6-phosphatase, TPNH-cytochrome c reductase).
- Electron microscopy for morphological assessment of purity.
Main Results:
- The isolation method yielded purified bovine retinal outer segment fragments.
- Mitochondrial contamination was less than 1%.
- Absence of significant microsomal enzyme activity.
- Electron microscopy confirmed the presence of outer segment discs with minimal other particles.
- Isolated fragments exhibited an ascorbate-oxidizing system and high lipid content.
Conclusions:
- Density gradient centrifugation effectively isolates highly purified bovine retinal outer segments.
- The preparation is suitable for biochemical studies due to minimal organelle contamination.
- The characterized ascorbate-oxidizing system and lipid content provide insights into outer segment function.