Electron microscopic visualization of fatty acids in tissues.

Area of Science:

• Biochemistry
• Cell Biology
• Histology

Background:

• Long-chain fatty acids are vital amphipathic molecules with significant structural and metabolic roles in tissues.
• Their derivation from triacylglycerol-rich particles and intracellular stores via tissue lipases is established.
• Conventional ultrastructural techniques have faced challenges in identifying and localizing fatty acids within tissues.

Purpose of the Study:

• To present novel ultrastructural techniques for studying fatty acid transport and localization in tissues.
• To demonstrate lipase activity and fatty acid generation from triacylglycerol in aldehyde-fixed tissues.
• To identify the ultrastructural forms of fatty acid accumulation in tissues.

Main Methods:

• Development and application of overlapping ultrastructural techniques.
• Analysis of aldehyde-fixed tissue sections and freeze-fracture replicas.
• Utilizing fatty acid ionization properties combined with freeze-fracture for molecular localization.

Main Results:

• Fatty acid accumulations appear as lamellar structures (40-50 Å periodicity) in resin-embedded sections.
• Hydrated myelin figures are observed in freeze-fracture replicas of both unfixed and fixed tissues.
• A new method successfully localized fatty acids to specific leaflets of membrane bilayers.

Conclusions:

• Novel ultrastructural methods enable the study of fatty acid transport and localization.
• Fatty acids form distinct ultrastructural arrangements within tissues.
• Fatty acids are precisely localized to membrane bilayers using ionization-based techniques.