Characterization of fifteen key genes involved in iron metabolism and their responses to dietary iron sources in yellow catfish Pelteobagrus fulvidraco

Abstract

Background: Iron is an essential metal element for organisms, whose metabolism is regulated by many genes and also dietary iron sources. However, the characterization, distribution and the responses of iron metabolism-related genes to different iron sources were not clear in fish.

Methods: The full-length cDNA sequences of fifteen iron metabolism-relevant genes (tf, tfr1, hp, fpn1, ho1, ho2, tfr2, hjv, hepcidin, fth, ftl, ftm, irp1, irp2 and hif2α.) were obtained via 3' and 5' RACE PCR from yellow catfish, a widely distributed freshwater teleost in China and other Asian countries. Their molecular characterizations were analyzed via the bioinformatic methods. Real-time quantitative PCR was used to explore their mRNA distribution in nine tissues. Their mRNA expression responses in four tissues (heart, brain, kidney and gill) were explored in yellow catfish fed diets with five iron sources, including ferrous sulfate (FeSO₄), ferrous bisglycinate (Fe-Gly), ferrous chloride (FeCl₂), ferric citrate (Fe-CA) and ferric oxide nanoparticles (Fe₂O₃NPs).

Results: Compared with mammals and other teleost, these members shared similar domains. Their mRNAs were expressed in nine tested tissues, but mRNA levels varied. Yellow catfish fed the diets containing Fe-Gly and Fe₂O₃NPs had higher iron contents in heart, brain, kidney and gill. Meantime, different dietary iron sources addition affected their mRNA expression differentially in brain, heart, kidney and gill. It should be pointed out that only three biological replicate tanks were used in the present feeding treatment, and more biological replicate tanks (more than five) should be emphasized in further researches.

Conclusion: Taken together, our study identified fifteen iron metabolism-relevant genes, explored their mRNA expression in nine tissues, and their mRNA expression in the responses to different dietary iron sources in four tissues, indicating their important regulatory function in iron metabolism and homeostasis.

Keywords: Dietary iron sources; Iron homeostasis; Molecular characterization; Pelteobagrus fulvidraco; Tissue mRNA expression.