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The assembly of the DNA complex present in chick embryo cell cytosol
Insights
Researchers identified early DNA and RNA complexes in chick embryo cytosol, which increase in molecular weight over time. This suggests a specific cytosolic DNA complex, not an artifact of cell culturing, can be distinguished from artefactual material.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Cytosolic DNA and RNA interactions are crucial for cellular processes.
- Understanding the nature and origin of DNA-RNA complexes in the cytosol is important.
- Previous studies have not fully elucidated the dynamic behavior of these complexes.
Purpose of the Study:
- To investigate the presence and characteristics of DNA and RNA complexes in chick embryo fibroblast cytosol.
- To determine if these complexes are specific cellular components or artifacts of cell culture.
- To track the molecular weight changes of these complexes over time.
Main Methods:
- Chromatographic separation of cytosol from chick embryo fibroblasts labeled with [3H]thymidine or [3H]uridine.
- Analysis of eluting fractions based on relative molecular mass.
- Comparison of cytosol from cultured cells versus whole, amniotically labeled chick embryos.
Main Results:
- Early-labeled DNA and RNA were detected, eluting at a relative molecular mass of approximately 1.5 x 10^5.
- These DNA-RNA complexes progressively shifted to a higher molecular weight peak (approximately 10^6).
- Similar patterns were observed in both cultured cells and whole embryos, indicating the complex is not a cell culture artifact.
Conclusions:
- A specific cytosolic DNA complex exists and exhibits dynamic molecular weight changes.
- The observed complex is not an artifact solely due to cell culturing techniques.
- Methods exist to differentiate between specific and artefactual DNA material within the cytosol.
Abstract:
Chromatography of chick embryo fibroblast cytosol labelled with [3H]thymidine or [3H]uridine precursors has shown the presence of early labelled DNA and RNA eluting at a position corresponding to a relative molecular mass of approximately 1.5-10(5). The early DNA-RNA (heteroduplex?) then moves progressively to a higher molecular weight peak, relative molecular mass approximately 10(6). The process appears similar in cytosol from cultured cells and from whole amniotically labelled chick embryos: consequently the cytosolic DNA complex is not an artefact of cell culturing. The relative contribution of artefactual and specific cytosol-associated DNA material is discussed: it is concluded that while both are present in cytosol as prepared, it is possible to discriminate between specific and artefactual DNA material.