Abstract
The effects of toxic exposures on the susceptibility of rainbow trout (Oncorhynchus mykiss) to saprolegniosis were evaluated. Fish were exposed to sublethal concentrations of copper (0.25 mg/liter), cyanide (0.07 mg/liter), ammonia (0.5 mg/liter), and nitrite (0.24 mg/liter) for 24 h. After exposure, the fish were challenged by Saprolegnia parasitica (3.6 x 10(sup6) zoospores per liter) for 10 min. Cortisol and cholesterol were used to indicate stress response. Similar increases of cortisol were found for the four tested chemicals. All fish with cortisol levels higher than 370 ng/ml developed the disease, while only 24% of the fish with cortisol levels lower than 370 ng/ml were infected. Cholesterol levels remained unchanged after toxic exposure. Increased susceptibilities to the pathogen were observed for ammonia (71%), copper (57%), nitrite (50%), and cyanide (33%). The increases in susceptibility as a result of cyanide and nitrite exposure could be explained by the stress response. For copper and ammonia, the combination of two different effects, the stress response and specific impairments of the defense mechanism of trout against saprolegniosis, should be considered.
Full Text
The Full Text of this article is available as a PDF (278.5 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Arakawa H., Maeda M., Tsuji A. Chemiluminescence enzyme immunoassay of cortisol using peroxidase as label. Anal Biochem. 1979 Sep 1;97(2):248–254. doi: 10.1016/0003-2697(79)90352-x. [DOI] [PubMed] [Google Scholar]
- Carballo M., Muñoz M. J. Effect of sublethal concentrations of four chemicals on susceptibility of juvenile rainbow trout (Oncorhynchus mykiss) to saprolegniosis. Appl Environ Microbiol. 1991 Jun;57(6):1813–1816. doi: 10.1128/aem.57.6.1813-1816.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ewing M. S., Ewing S. A., Zimmer M. A. Sublethal copper stress and susceptibility of channel catfish to experimental infections with Ichthyophthirius multifiliis. Bull Environ Contam Toxicol. 1982 Jun;28(6):674–681. doi: 10.1007/BF01605635. [DOI] [PubMed] [Google Scholar]
- Hetrick F. M., Knittel M. D., Fryer J. L. Increased susceptibility of rainbow trout to infectious hematopoietic necrosis virus after exposure to copper. Appl Environ Microbiol. 1979 Feb;37(2):198–201. doi: 10.1128/aem.37.2.198-201.1979. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Huey D. W., Beitinger T. L., Wooten M. C. Nitrite-induced methemoglobin formation and recovery in channel catfish (Ictalurus punctatus) at three acclimation temperatures. Bull Environ Contam Toxicol. 1984 Jun;32(6):674–681. doi: 10.1007/BF01607555. [DOI] [PubMed] [Google Scholar]
- Nolard-Tintigner N. Etude expérimentale sur l'épidémiologie et la pathogénie de la saprolégniose chez Lebistes reticulatus Peters et Xiphophorus helleri Heckel. Acta Zool Pathol Antverp. 1973 Mar;57:1–127. [PubMed] [Google Scholar]
- Pickering A. D., Christie P. Changes in the concentrations of plasma cortisol and thyroxine during sexual maturation o the hatchery-reared brown trout, Salmo trutta L. Gen Comp Endocrinol. 1981 Aug;44(4):487–496. doi: 10.1016/0016-6480(81)90337-3. [DOI] [PubMed] [Google Scholar]
- Richmond W. Preparation and properties of a cholesterol oxidase from Nocardia sp. and its application to the enzymatic assay of total cholesterol in serum. Clin Chem. 1973 Dec;19(12):1350–1356. [PubMed] [Google Scholar]
- Sohnle P. G., Chusid M. J. Defense against infection with filamentous fungi in rainbow trout. Comp Biochem Physiol A Comp Physiol. 1983;74(1):71–76. doi: 10.1016/0300-9629(83)90714-4. [DOI] [PubMed] [Google Scholar]