(full paper is archived in the Miller Library)
Title: Identification of suspected Carnobacteria sp.
isolated from the brains of beached Salmon sharks (Lamna
ditropis).
Student Author(s): Schaffer, Paula
Faculty Advisor(s): Palumbi, Stephen
Pages: 18
Location: Final Papers Biology 199H
Date: June 2004
Abstract: Juvenile salmon sharks beach yearly along the
California coast during late summer and early fall. To determine the
epidemiological condition of beached animals, frozen and formalin
fixed beached specimens were collected from various Fish and Game
facilities for examination and freshly beached specimens were also
examined when possible. Histology revealed meningoencephalitis with
intralesional bacteria in almost all of the specimens, including the
freshly beached sharks, suggesting that this infection plays a role
in this unusual behavior. The pathogenic bacteria was cultured from
four separate shark specimens, and each isolate was characterized
serologically and biochemically as belonging to the genus
Carnobacteria. In order to identify the species, we sequenced
~540 bp of the 16s ribosomal DNA and a similarly sized portion of the
large ribosomal DNA intergenic spacer (ITS or ISR). The 16s
sequences obtained from all samples were identical and 99% similar to
C. piscicola. The ISR sequences obtained from all samples
were also identical to each other, but were only 92% homologous to
C. piscicola, and did not match closely with any other
sequence in GenBank. This is the first report of
Carnobacterium infection in any shark species, though the
identity of the pathogenic bacteria remains uncertain.