Cyndy Masada has worked as a molecular biologist and microbiologist at the NWFSC since 1993. She joined the Utilization Research Division (now the Resource Enhancement and Utilization Technologies Division) as a National Research Council postdoctoral associate after receiving a Ph. D. from the Department of Microbiology and Molecular Genetics at UCLA in 1993, where her dissertation work focused on prokaryotic RNA processing, degradation, and anti-sense RNA control of the mobile genetic element, Tn10. Her postdoctoral research involved studying the bacterial pathogenesis of Aeromonas hydrophila, a Gram-negative organism that causes disease in amphibians, reptiles, fish, and humans. Currently, her research efforts focus on A. salmonicida, a Gram-negative fish pathogen that causes the disease furunculosis in salmonids.
Aeromonas salmonicida is an opportunistic and ubiquitous fish pathogen that causes furunculosis in salmonids. A number of individual extracellularly secreted proteins and bacterial surface factors have been implicated in the virulence and pathogenesis of A. salmonicida. Current research is aimed at determining whether type IV pili, surface structures that have been shown to be important virulence determinants of many Gram-negative pathogens, are involved in A. salmonicida pathogenesis. We isolated and characterized a four-gene cluster, tapABCD, which encodes proteins homologous to components required for type IV pilus biogenesis. One of the genes, tapA, encodes a type IV pilin subunit. When we mutated the tapA gene, we found that this defective A. salmonicida strain was slightly less pathogenic than wild type for juvenile Oncorhynchus mykiss (rainbow trout) when delivered by intraperitoneal injection and it is also less pathogenic than wild type for juvenile Oncorhynchus tshawytscha (chinook salmon) when delivered by immersion. These studies are geared towards eventually developing a vaccine against A. salmonicida.
As a member of the Fish Health/Microbiology Team's disease diagnostic support staff, I am also involved with the ESA Captive Broodstock Program and a US Army Corps of Engineers project studying delayed mortality of juvenile chinook salmon smolts in the Columbia River Basin.