Dil and diO: versatile fluorescent dyes for neuronal labelling and pathway tracing

Area of Science:

• Neuroscience
• Cell Biology
• Developmental Biology

Background:

• Fluorescent carbocyanine dyes DiI and DiO, widely used in cell biology, have recently emerged as valuable neuronal tracers.
• Initial studies in 1985 demonstrated their efficacy in tracing neuronal connections in developing nervous systems.

Purpose of the Study:

• To review the properties, uses, and advantages of carbocyanine dyes as neuronal tracers.
• To highlight their application in developmental neurobiology research.

Main Methods:

• Utilized DiI and DiO dyes for retrograde and anterograde tracing in developing neuronal systems.
• Investigated dye retention, labeling patterns (cell bodies and processes), and toxicity in cultured neurons.
• Examined dye translocation mechanisms, proposing lateral membrane diffusion over axonal transport.

Main Results:

• Carbocyanine dyes were found to be excellent retrograde and anterograde tracers.
• Dyes were retained in cultured neurons, labeling both cell bodies and processes with apparent non-toxicity.
• Evidence supported lateral membrane diffusion as the primary translocation mechanism, further validated by fixed-tissue labeling.

Conclusions:

• Carbocyanine dyes offer a versatile and effective tool for neuronal tracing in developmental neurobiology.
• Their mechanism of membrane diffusion allows for labeling in various experimental conditions, including fixed tissues.
• These dyes have facilitated significant advancements in understanding neuronal development.