Submitted to: Aquaculture Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/1/2007
Publication Date: 2/26/2007
Citation: Zhang, Y., Shoemaker, C.A., Klesius, P.H., Arias, C. 2007. Differential gene expression of putative virulence genes in flavobacterium columnare. Aquaculture Conference Proceedings.Aquaculture 2007. February 26 - March 2, 2007 San Antonio , Texas. p. 34.
Technical Abstract: A shot-gun genomic library of the Flavobacterium columnare ALG-530 virulent strain has been constructed and more than 3,000 clones have been sequenced to date (800 contigs). Based on sequence identity with putative known virulence genes from related species, seven genes were selected for differential expression analysis. These genes are: transmembrane rod-shape determining protein gene (rod), ferrochelatase gene (hemH), glycosyltransferase gene (gtf), thioredoxin gene (trx), thiamine biosynthesis protein gene (thiC), nitric-oxide reductase gene (norB), and two gliding genes (homlologous to Flavobacterium johnsoniae gldB and gldC, respectively). A collection of 31 F. columnare isolates were tested for the presence of these seven genes. Not all the isolates contained all the genes; however, isolates belonging to the same genomovar presented almost an identical gene profile. Ten isolates of F. columnare (from both genomovars I and II) were chosen for gene expression study. The expression profile of the genes tested varied when all strain were grown in vitro under identical conditions. ALG-530 was chosen for gene expression comparison when grown in normal broth, iron-limited broth and catfish skin presence conditions. Expression of the thiamine gene, glycosyltransferase gene, and gliding gene (gldB) was not detected under any conditions. The remaining five genes were strongly expressed within 2h incubation in normal Shieh broth, but the expression under iron-limited conditions varied. Gene expression level in the presence of catfish skin was lower than under other conditions. To our knowledge, this is the fist time differential gene expression in F. columnare has been shown. Our study opens the door to further studies on F. columnare gene expression.