Spleen index and mannose-binding lectin levels in four channel catfish families exhibiting different susceptibilities to Flavobacterium columnare and Edwardsiella ictaluri.

Edwardsiella ictaluri and Flavobacterium columnare are two bacterial pathogens that affect channel catfish Ictalurus punctatus aquaculture. At the Catfish Genetics Research Unit (U.S.

Expression of leptin-like peptide (LLP) mRNA in channel catfish (Ictalurus punctatus) is induced by exposure to Edwardsiella ictaluri but is independent of energy status.

Leptin is a key pleiotropic cytokine involved in regulation of energy homeostasis and immunity in mammals. In channel catfish, the presence of a partial messenger RNA sequence that encodes a leptin-like peptide (LLP) has been identified and investigated. The objectives of the present studies were to clone and characterize full-length catfish LLP gene, examine tissue expression of LLP mRNA, and determine effects of prolonged fasting and exposure to Edwardsiella ictaluri (E.

Edwardsiella ictaluri encodes an acid-activated urease that is required for intracellular replication in channel catfish (Ictalurus punctatus) macrophages.

Genomic analysis indicated that Edwardsiella ictaluri encodes a putative urease pathogenicity island containing the products of nine open reading frames, including urea and ammonium transporters. In vitro studies with wild-type E. ictaluri and a ureG::kan urease mutant strain indicated that E.

Validation of a whole-body cortisol extraction procedure for channel catfish (Ictalurus punctatus) fry.

We validated a whole-body cortisol extraction technique for channel catfish, Ictalurus punctatus, fry. Three volume enhancement methods were tested: CAL method (zero calibrator A diluent added to lipid extract), PBS method (phosphate buffered saline added to lipid extract), and VO method (food grade vegetable oil added to lipid extract). The volume enhancement extracts were evaluated using a commercial radioimmunoassay kit.

Proteomic analysis of head kidney tissue from high and low susceptibility families of channel catfish following challenge with Edwardsiella ictaluri.

A study was performed to compare proteomic profiles of channel catfish from families with high and low susceptibility to Edwardsiella ictaluri following an immersion challenge. Total protein was isolated from head kidney samples, collected at 2 and 6h postexposure, and analyzed by 2-D-gel electrophoresis coupled with peptide mass fingerprint analysis by matrix-assisted laser desorption/ionization and time of flight tandem mass spectrometry. Comparisons were made between proteomic profiles from infected and uninfected fish from high and low susceptibility families.

Signature-tagged mutagenesis of Edwardsiella ictaluri identifies virulence-related genes, including a salmonella pathogenicity island 2 class of type III secretion systems.

Edwardsiella ictaluri is the leading cause of mortality in channel catfish culture, but little is known about its pathogenesis. The use of signature-tagged mutagenesis in a waterborne infection model resulted in the identification of 50 mutants that were unable to infect/survive in catfish. Nineteen had minitransposon insertions in miscellaneous genes in the chromosome, 10 were in genes that matched to hypothetical proteins, and 13 were in genes that had no significant matches in the NCBI databases.

RecA and RadA proteins of Brucella abortus do not perform overlapping protective DNA repair functions following oxidative burst.

Very little is known about the role of DNA repair networks in Brucella abortus and its role in pathogenesis. We investigated the roles of RecA protein, DNA repair, and SOS regulation in B. abortus.