Geology topics

Deborah D. Cartwright

Publications and source records attributed to Deborah D. Cartwright.

3 recordsLinked to original sources

USGS2004

Comparative susceptibility of Atlantic salmon, lake trout and rainbow trout to Myxobolus cerebralis in controlled laboratory exposures

The susceptibility of lake trout Salvelinus namaycush , rainbow trout Oncorhynchus mykiss and Atlantic salmon Salmo salar to Myxobolus cerebralis , the causative agent of whirling disease, was compared in controlled laboratory exposures. A total of 450 (225 for each dose) fry for each species were exposed to a low (200 spores per fish) or high (2000 spores per fish) dose of the infective triactinomyxon. At 22 wk post-exposure, 60 fish from each group, as well as controls for each species, were examined for clinical signs (whirling behavior, blacktail, deformed heads and skeletal deformities), microscopic lesions, and presence of spores. Rainbow trout were highly susceptible to infection, with 100% being positive for spores and with microscopic pathological changes in both exposure groups. Rainbow trout were the only species to show whirling behavior and blacktail. Atlantic salmon were less susceptible, with only 44 and 61% being positive for spores, respectively, in the low and high dose groups, while 68 and 75%, respectively, had microscopic pathology associated with cartilage damage. Rainbow trout heads contained mean spore concentrations of 2.2 (low dose) or 4.0 (high dose) × 10 6 spores g tissue -1 . The means for positive Atlantic salmon (not including zero values) were 1.7 (low) and 7.4 (high) × 10 4 spores g tissue -1 . Lake trout showed no clinical signs of infection, were negative for spores in both groups and showed no histopathological signs of M. cerebralis infection.

Diseases of Aquatic Organisms↗

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↗

USGS2001

A comparison of susceptibility to Myxobolus cerebralis among strains of rainbow trout and steelhead field and laboratory trials

Three strains of rainbow trout and steelhead Oncorhynchus mykiss were evaluated for the presence of whirling disease in field and laboratory trials. In the field exposures, fingerling Salmon River steelhead and Cayuga Lake and Randolph strains of rainbow trout were placed in wire cages in an earthen, stream-fed pond in New York State that was known to harbor Myxobolus cerebralis. Control fish were held at another hatchery that was free of whirling disease. In the controlled trials at the National Fish Health Research Laboratory, fingerling steelhead and Cayuga Lake and Mount Lassen rainbow trout were exposed to triactinomyxons at low (200 triactinomyxons/fish) or high (2,000 triactinomyxons/fish) levels for 2 h. Controls of each group were sham-exposed. Following an incubation period of 154 d for laboratory trials and 180 d for field trials, cranial tissue samples were taken for spore enumeration (field and laboratory trials) and histological analyses (laboratory only). Clinical signs of disease, including whirling behavior, blacktail, and skeletal deformities, were recorded for each fish in the laboratory trial at the terminal sampling. No clinical evidence of disease was noted among fish in the field trials. Clinical signs were noted among all strains in the laboratory trials at both exposure levels, and these signs were consistently greatest for the Mount Lassen strain. Whirling and skeletal deformities were more evident in the steelhead than in the Cayuga Lake rainbow trout; blacktail was more common in the Cayuga Lake fish. In both field and laboratory trials, spore counts were significantly higher for Cayuga Lake rainbow trout than in steelhead. In laboratory trials, moderate to marked cranial tissue lesions predominated in all three strains.

New York↗