# Ferritin, N-Acetylated α-Linked Acidic Dipeptidase 2, and Cytoplasmic Aconitate Hydratase Are Associated with Iron Metabolism and Regulate Iron Content in the Razor Clam, Sinonovacula constricta

## TL;DR

This study identifies genes involved in iron metabolism in razor clams, showing how they regulate iron levels in response to environmental changes.

## Contribution

The study reveals the role of ScFER, ScNAALAD2, and SccAH in iron regulation in the razor clam, particularly highlighting ScFER's central function.

## Key findings

- ScFER expression increases with higher iron exposure, suggesting a role in iron storage.
- Knocking down SccAH leads to increased ScFER expression and iron content.
- ScNAALAD2 and SccAH activity decreases under iron stress, indicating transport and regulatory roles.

## Abstract

Iron is a vital nutrient, but how mollusks manage iron in their bodies is not well understood. This study aimed to identify the key genes controlling iron levels in the razor clam. We focused on three genes, namely, ScFER, ScNAALAD2, and SccAH, involved in iron storage, transport, and regulation, respectively. When razor clams were exposed to more iron, the iron level rose in their hepatopancreas. At the same time, the activity of the storage gene increased, while the activities of the transport and regulatory genes decreased. Further experiments showed that reducing the activity of the regulatory gene led to higher activity of the storage gene and increased iron content. These results suggest that the iron storage gene ScFER likely plays a central role in controlling iron levels in the razor clam. This research helps us understand how mollusks process iron, which can inform strategies to improve mollusk nutrition and monitor environmental health.

Iron is an important trace element, but there are few studies on iron metabolism in mollusks, and the key genes regulating iron content are still unclear. Our previous experiments have found that higher iron content was detected in the hepatopancreas and kidney of razor clam (Sinonovacula constricta). To clarify the key genes regulating the iron content in S. constricta, we focused on three candidates: Ferritin (ScFER), responsible for iron storage; N-acetylated α-linked acidic dipeptidase 2 (ScNAALAD2), involved in iron transport; Cytoplasmic aconitate hydratase (SccAH), which may participate in the post-transcriptional regulation of ScFER and ScNAALAD2. Furthermore, their expression patterns and gene regulation under iron stress were further explored. When the external iron concentration increased, the iron content was at its highest levels in the hepatopancreas, and the expression of ScNAALAD2 and SccAH decreased to the lowest levels, while the expression of ScFER increased. This suggests the possible transport and storage functions of these three genes in iron metabolism. In addition, after knocking down SccAH, the expression levels of ScFER increased, and the iron content also increased, further confirming the potential relationship between ScFER and iron content. Overall, we speculated that ScFER may play an important role in regulating the iron content of S. constricta. This study provides reference data for improving the iron metabolism pathway and exploring the main genes affecting iron content in mollusks.