Question

After six hours, the plants were frozen in liquid nitrogen, before being put on Tom photographic film to make the autoradiograph. Suggest why the plants must be frozen quickly.

Answer 1

Answer:

Microautoradiography (MAR) is a conventional imaging method based on the daguerreotype. The technique is used to visualize the distribution of radionuclide-labeled compounds within a tissue section. However, application of the classical MAR method to plant tissue sections is associated with several difficulties. In this study, we report an MAR method applicable to fresh-frozen plant sections. Our method had two features: (i) the sample was kept frozen from plant tissue collection to radioisotope detection, making it possible to fix solutes without solvent exchange; and (ii) 1.2 µm thick polyphenylene sulfide film was inserted between the fresh-frozen plant section and the photosensitive nuclear emulsion to separate the section from the emulsion before autoradiography was conducted, which significantly improved the quality of the section until microscopic detection, the quality of the MAR image and the success rate. Then, the passage of cadmium (Cd) through vegetative rice stem tissue after 24 h of (109)Cd absorption was described for the first time using the MAR method. MAR clearly revealed the distribution of (109)Cd at the tissue level with high resolution. The (109)Cd concentration in phloem cells was found to be particularly high, whereas the xylem cells contained only small amounts of (109)Cd. The MAR method was also applicable for detecting (109)Cd and [(33)P]phosphate in roots. The MAR method developed here is expected to provide distribution images for a variety of compounds and ions in plant tissue.

Explanation:

Answer 2

The plants must be frozen quickly to preserve them and stop them from getting spoilt.

• An autoradiograph is a photograph of an object produced by radiation from radioactive material in the object.
• This technique is widely used in biology for various purposes like measuring the rate of DNA replication and detection of protein phosphorylation.
• Autoradiographs can also be viewed as digital images due to the advancement in technology that humans have achieved.
• The plants are frozen in liquid nitrogen to make sure that the leaves are preserved.
• As freezing slows down the process of decaying and also freezes the plant which helps during autoradiography.
• Thus, the plants must be frozen quickly to preserve them and stop them from getting spoilt.

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