Location: Warmwater Aquaculture Research UnitTitle: Molecular responses of calreticulin genes to iron overload and bacterial challenge in channel catfish Ictalurus punctatus Author
|Waldbieser, Geoffrey - Geoff|
Submitted to: Developmental and Comparative Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2010
Publication Date: N/A
Citation: N/A Interpretive Summary: Losses to disease are a major limitation in catfish production, and understanding the catfish immune system would help researchers and breeders identify mechanisms and strategies for limiting mortality in catfish production. This research built upon previous experiments that showed calreticulin gene expression was strongly increased after experimental exposure to E. ictaluri, a major bacterial pathogen. The present research revealed catfish contain at least three calreticulin genes, and expression of these three genes increased after exposure to bacteria or iron. These experiments revealed the calreticulin genes as candidate loci for the identification of genetic variation in disease responses in catfish populations.
Technical Abstract: Infection and inflammation are often accompanied by oxidative stress caused by the accumulation of reactive oxygen species which can be deleterious to the health of the host. Antioxidant defense mechanisms and components are crucial in limiting cellular and tissue-level damage and restoring homeostasis. In mammals, calreticulin is a 46-kDa multifunctional calcium binding protein of the endoplasmic reticulum that has many critical functions in the eukaryotic cell including regulation of intracellular calcium homoeostasis, lectin binding and chaperoning, and oxidative stress responses. In previous studies from our lab, the calreticulin gene was observed to be strongly upregulated in catfish during challenge with infectious Gram-negative bacteria. However, little is known about the function of this gene in teleost fish. The objective of this study, therefore, was to characterize the calreticulin gene from channel catfish, to determine its genomic organization, to profile its patterns of tissue expression, and to establish its potential for physiological antioxidant and immune responses in catfish after bacterial infection with Edwardsiella ictaluri and iron treatment. Our results indicate that there are at least three calreticulin related genes in the catfish genome. The three calreticulin genes are widely expressed in various tissues under homeostatic conditions and their expression showed significant upregulation following infection and/or iron level changes.