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David T. Gauthier

Publications and source records attributed to David T. Gauthier.

4 recordsLinked to original sources
USGS2007

Mycobacterial infections in striped bass from Delaware Bay

Eighty striped bass Morone saxatilis were obtained from Delaware Bay using commercial gill nets set adjacent to Woodland Beach (n = 70) and Bowers Beach (n = 10) in December 2003. Fish were examined for gross lesions. Total lengths (TLs) and eviscerated weights were determined to calculate condition factors (K). Portions of spleens were aseptically harvested for bacterial culture, and portions of spleens, kidneys (anterior and posterior), livers, and gonads were obtained for histological examination. The size distribution of the striped bass was relatively homogeneous; the mean TL was about 600 mm for all samples. Mean K exceeded 0.95 in all samples and was not significantly different (P > 0.05) among samples. Significant differences in mycobacterial infection prevalence (P ??? 0.05) were observed among samples; samples obtained at Woodland Beach (WB) on December 10 (53.8%, n = 13) and December 17 (7.1%, n = 42) exhibited the most striking differences in prevalence. Mycobacterial infection intensity ranged from 1 ?? 102 to 1 ?? 107 colony-forming units per gram of spleen. Acanthocephalan infection prevalence and intensity, non-acid-fast bacterial infection prevalence, and fish sex ratio were also significantly different among the samples (P ??? 0.05). Similar to the mycobacterial infections, differences in sex ratio, acanthocephalan infection, and non-acid-fast bacterial infection were observed between the WB samples taken on December 10 and 17. However, no significant associations (P > 0.05) were observed between sex ratio or these infections and mycobacterial infection. The differences in bacterial and parasite infection prevalence and intensity and fish sex ratio in some samples indicate that these fish had a different history and that the epizootiology of mycobacterial infection in striped bass from Delaware Bay may be relatively complex. ?? Copyright by the American Fisheries Society 2007.

Journal of Aquatic Animal Health↗
USGS2003

Measurement of in vitro leucocyte mitogenesis in fish: ELISA based detection of the thymidine analogue 5'-bromo-2'-deoxyuridine

In this study we present a method for the measurement of in vitro mitogenesis in fish leucocytes that is based on the incorporation of the thymidine analogue 5′-bromo-2′-deoxyuridine (BrdU) into the DNA of replicating cells, followed by ELISA-based detection. This technique, adapted from methods developed for mammalian cells, operates on a similar biological principle to 3 H-thymidine incorporation, but circumvents the logistical and safety issues inherent with the radioactive label. Because it directly measures DNA proliferation, the assay has advantages over other colorimetric methods that may be strongly influenced by leucocyte metabolic status. Using BrdU incorporation followed by ELISA, we evaluate the responsiveness of rainbow trout ( Oncorhynchus mykiss [Walbaum]) leucocytes to the mammalian T-cell mitogen Concanavalin A (Con A) as well as the differential response of white perch ( Morone americana [Gmelin]) leucocytes to Con A and pokeweed mitogen. Specific considerations intrinsic to the assay system are discussed, including the implications of utilising enzyme-based detection.

Fish and Shellfish Immunology↗
USGS2003

Experimental mycobacteriosis in striped bass Morone saxatilis

Striped bass Morone saxatilis were infected intraperitoneally with approximately 10 5 Mycobacterium marinum, M. shottsii sp. nov., or M. gordonae. Infected fish were maintained in a flow-through freshwater system at 18 to 21°C, and were examined histologically and bacteriologically at 2, 4, 6, 8, 17, 26, 36 and 45 wk post-infection (p.i.). M. marinum caused acute peritonitis, followed by extensive granuloma development in the mesenteries, spleen and anterior kidney. Granulomas in these tissues underwent a temporal progression of distinct morphological stages, culminating in well-circumscribed lesions surrounded by normal or healing tissue. Mycobacteria were cultured in high numbers from splenic tissue at all times p.i. Standard Ziehl-Neelsen staining, however, did not demonstrate acid-fast rods in most early inflammatory foci and granulomas. Large numbers of acid-fast rods were present in granulomas beginning at 8 wk p.i. Between 26 and 45 wk p.i., reactivation of disease was observed in some fish, with disintegration of granulomas, renewed inflammation, and elevated splenic bacterial densities approaching 10 9 colony-forming units g -1 . Infection with M. shottsii or M. gordonae did not produce severe pathology. Mild peritonitis was followed by granuloma formation in the mesenteries, but, with 1 exception, granulomas were not observed in the spleen or anterior kidney. M. shottsii and M. gordonae both established persistent infections in the spleen, but were present at densities at least 2 orders of magnitude less than M. marinum at all time points observed. Granulomas in the mesenteries of M. shottsii- and M. gordonae-infected fish resolved over time, and no reactivation of disease was observed.

Diseases of Aquatic Organisms↗