3D gold in situ labelling in the EM

Area of Science:

• Cell Biology
• Microscopy Techniques
• Plant Science

Background:

• Traditional in situ hybridization methods for electron microscopy often lack sufficient sensitivity and can compromise ultrastructure.
• Studying the 3D organization of molecular components within cells requires high-resolution imaging and labeling techniques.

Purpose of the Study:

• To develop and validate a novel pre-embedding in situ hybridization (ISH) labeling method for enhanced sensitivity and ultrastructural preservation in electron microscopy (EM).
• To apply this method for investigating the 3D organization of ribosomal DNA (rDNA) in pea root tissue.

Main Methods:

• Developed a pre-embedding ISH protocol involving vibratome sectioning of plant tissue.
• Applied 1 nm gold-conjugated antibodies for labeling, followed by silver enhancement.
• Embedded labeled sections in resin for standard electron microscopy processing and imaging.
• Utilized stereo-pair recording, tomographic reconstruction, and serial sectioning for 3D analysis.

Main Results:

• Achieved significantly higher sensitivity and labeling levels compared to previous EM ISH methods.
• Maintained excellent ultrastructural preservation of plant tissues.
• Demonstrated the capability to study the 3D arrangement of labeled targets throughout the specimen depth.
• Successfully applied the method to visualize rDNA organization in pea root cells.

Conclusions:

• The novel pre-embedding ISH method offers a substantial improvement in sensitivity and resolution for EM studies.
• This technique enables detailed 3D visualization of molecular organization within intact cellular structures.
• The method is effective for studying complex nuclear organizations, such as rDNA, in plant tissues.