Gene organization and expression of the divalent cation transporter Nramp in the protistan parasite Perkinsus marinus

Area of Science:

• Parasitology
• Molecular Biology
• Marine Biology

Background:

• Perkinsus marinus infects eastern oysters, Crassostrea virginica, residing within host hemocytes.
• Host divalent cation transporters, like Nramp1, influence intracellular parasite survival.
• Limited knowledge exists on parasite Nramp family genes and their role in host defense evasion.

Purpose of the Study:

• To characterize the Nramp gene from Perkinsus marinus (PmNramp).
• To investigate the evolutionary relationship of PmNramp with other Nramp family members.
• To explore preliminary functional aspects of PmNramp related to parasite survival.

Main Methods:

• Obtained PmNramp cDNA sequence using PCR and rapid amplification of cDNA ends.
• Analyzed the gene structure, including exons, introns, and splicing signals.
• Performed phylogenetic analysis to determine evolutionary relationships.
• Conducted preliminary in vitro studies on PmNramp expression.

Main Results:

• A 2,082-bp cDNA sequence for PmNramp was obtained, encoding a 558-amino acid protein.
• PmNramp is a single-copy gene with 7 exons and 6 short introns.
• Phylogenetic analysis suggests a common ancestor for P. marinus and apicomplexan Nramp genes, with apicomplexan Nramps being highly divergent.
• Preliminary data indicate that PmNramp expression is modulated by metals and oxidative stress.

Conclusions:

• The characterization of PmNramp provides a molecular basis for understanding its role in P. marinus survival.
• PmNramp's evolutionary position suggests unique adaptations within the Nramp family.
• Further research into PmNramp function could reveal novel targets for controlling oyster diseases.