A transmission electron microscopic (TEM) method for determining structural colors reflected by lizard iridophores

Area of Science:

• Biophysics
• Structural Biology
• Animal Coloration

Background:

• Iridescent tissue colors are attributed to iridophores utilizing thin-layer interference.
• Structural parameters like platelet width and spacing dictate reflected light wavelengths.

Purpose of the Study:

• To test a thin-layer interference model using transmission electron microscopy (TEM) measurements of lizard iridophores.
• To validate the model's ability to predict tissue color based on ultrastructure, accounting for TEM artifacts.

Main Methods:

• Transmission electron microscopy (TEM) was used to measure iridophore structural parameters in three lizard species.
• A thin-layer interference model was applied to predict light reflectance.
• Pigment contributions were factored into the analysis.

Main Results:

• The study found that tissue color corresponded with predicted iridophore reflectances when pigment contributions were considered.
• The model successfully predicted reflected wavelengths based on TEM-derived structural data.
• The research provides a method to calculate cytoplasmic shrinkage caused by TEM processing.

Conclusions:

• The thin-layer interference model, despite TEM-induced artifacts, accurately predicts iridophore-based coloration in lizards.
• This validates the model and its underlying assumptions for studying structural color mechanisms.
• The study offers insights into quantifying TEM processing effects on biological ultrastructure.