# Mature Erythrocytes of Iguana iguana (Squamata, Iguanidae) Possess Functional Mitochondria

## TL;DR

This study shows that mature red blood cells in iguanas have functional mitochondria, which is unusual in most vertebrates.

## Contribution

The paper demonstrates functional mitochondria in mature erythrocytes of Iguana iguana, challenging common biological assumptions.

## Key findings

- Mitochondria are present in mature erythrocytes of Iguana iguana with well-structured cristae.
- Erythrocyte mitochondria are polarized and localized in a perinuclear region.
- Red blood cells consume oxygen, indicating functional oxidative phosphorylation.

## Abstract

Electron microscopy analyses of Iguana iguana blood preparations revealed the presence of mitochondria within erythrocytes with well-structured cristae. Fluorescence microscopy analyses upon incubation with phalloidin-FITC, Hoechst 33342 and mitochondrial transmembrane potential (Δψm)-sensitive probe MitoTracker Red indicated that mitochondria i) widely occur in erythrocytes, ii) are polarized, and iii) seem to be preferentially confined at a "perinuclear" region, as confirmed by electron microscopy. The analysis of NADH-dependent oxygen consumption showed that red blood cells retain the capability to consume oxygen, thereby providing compelling evidence that mitochondria of Iguana erythrocytes are functional and capable to perform oxidative phosphorylation.