Frog iron storage protein gene linked to fighting off bacterial infections

Jenn Hoskins
17th December, 2025

Frog iron storage protein gene linked to fighting off bacterial infections

Rana dybowskii

Photo adapted from: Сергей Грабчак / CC BY (Source)

Key Findings

  • In Northeast China’s frog Rana dybowskii, the study cloned and analyzed the Fer-H gene, finding high similarity to other frog species
  • Following bacterial infection with Aeromonas hydrophila, the frog showed increased activity of some antioxidant enzymes, indicating oxidative stress
  • The Fer-H gene expression significantly increased in tissues like the liver and muscle after infection, suggesting a role in the frog’s immune response
Iron is essential for life, playing a critical role in numerous biological processes. However, free iron is toxic, so organisms have evolved mechanisms to store and manage it safely. Ferritin is a key protein involved in this process, acting as an iron reservoir and also participating in immune responses. Researchers at Harbin Normal University and Versiti Blood Research Institute recently investigated the role of ferritin in the frog Rana dybowskii[1]. This study aimed to understand how ferritin contributes to the frog’s defense against bacterial infections. The research team started by isolating the gene coding for the ferritin heavy chain (Fer-H) from R. dybowskii. This was achieved using a technique called polymerase chain reaction (PCR), which allows scientists to amplify specific DNA sequences. Once isolated, the gene was analyzed using bioinformatics – computational tools to understand its structure and function. The Fer-H gene was found to be 534 base pairs long and encodes a protein of 177 amino acids, containing a recognizable ‘Ferritin domain’ – the part of the protein responsible for iron storage. Comparing this gene to those of other species revealed the highest similarity with the ferritin gene of Rana temporaria (94% identical). To understand the Fer-H gene’s function, the researchers created an inflammation model by infecting frogs with the bacterium Aeromonas hydrophila (Ah). They then examined tissues for signs of oxidative stress, a type of cellular damage caused by an imbalance of reactive molecules. They measured the activity of several antioxidant enzymes – proteins that protect cells from oxidative damage. The results showed a significant increase in the activity of superoxide dismutase (SOD) and catalase (CAT), enzymes that break down harmful molecules. However, the activity of glutathione peroxidase (GSH-Px) decreased, indicating that the bacterial infection was causing significant oxidative damage to the frogs. Further analysis confirmed that the Fer-H gene is active in all tissues tested within R. dybowskii. Importantly, the amount of Fer-H gene expression increased substantially after bacterial infection. This was confirmed using quantitative real-time PCR (qRT-PCR), a sensitive method for measuring gene expression levels, and Western blot analysis, which detects the amount of the Fer-H protein present. The increased expression was particularly noticeable in the liver and muscle tissues. These findings suggest that the Fer-H gene plays a crucial role in the frog’s immune response to bacterial infection. The increase in Fer-H expression likely helps the frog store iron safely and combat the oxidative stress caused by the infection. This ties into broader understanding of ferritin function, as described in earlier studies[2], which demonstrated ferritin’s cytoprotective role against oxidative damage across various eukaryotic organisms. The study also builds upon previous research identifying ferritins as key players in immune defense[3]. The upregulation of the PcFer gene in crayfish tissues after exposure to heavy metals and lipopolysaccharide (a component of bacterial cell walls) mirrors the increased RdFer-H expression observed in infected frogs. This suggests a common mechanism of ferritin activation in response to microbial challenges across different species. Furthermore, the structure of ferritins, with their eight hydrophilic channels facilitating iron entry[4], provides a physical basis for their role in managing iron levels during an immune response. The di-Fe(III) peroxo intermediate formation at the ferroxidase site, and subsequent mineral core formation, highlights the complex process of iron storage within the protein shell, and how this process may be modulated during infection. The research team hypothesizes that the Fer-H gene contributes to R. dybowskii’s immune response during bacterial infection, expanding the knowledge base for exploring anti-infection immune mechanisms in amphibians.

HealthGeneticsAnimal Science

References

Main Study

1) Identification of Rana dybowskii Ferritin-Heavy chain gene and analysis of its role during bacterial infection

Published 16th December, 2025

https://doi.org/10.1371/journal.pone.0337205

Related Studies

2) The importance of eukaryotic ferritins in iron handling and cytoprotection.

https://doi.org/10.1042/BJ20150787

3) A ferritin gene from Procambarus clarkii, molecular characterization and in response to heavy metal stress and lipopolysaccharide challenge.

https://doi.org/10.1016/j.fsi.2017.02.025

4) Mineralization in ferritin: an efficient means of iron storage.

Journal: Journal of structural biology, Issue: Vol 126, Issue 3, Jun 1999


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