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United States Department of Agriculture

Agricultural Research Service

Title: Genetic Selection and Molecular Analysis of Domesticated Rainbow Trout for Enhanced Growth on Alternative Diet Sources.

Authors
item Overturf, Kenneth
item Lapatra, Scott - CLEAR SPRINGS BUHL, ID
item Hardy, Ron - UOFID, HAGERMAN, ID
item Bullock, Daniel

Submitted to: Environmental Geology and Water Sciences
Publication Type: Book / Chapter
Publication Acceptance Date: July 1, 2003
Publication Date: June 1, 2004
Citation: Overturf, K.E., Lapatra, S., Hardy, R., Bullock, D.G. 2004. Genetic selection and molecular analysis of domesticated rainbow trout for enhanced growth on alternative diet sources.. Environmental Geology and Water Sciences. Environmental Biology of Fishes 69:409-418.

Interpretive Summary: Molecular analysis of gene expression was used to monitor the transcription level of specific genes and determine how change in their expression level relates to diet, metabolism and immune response. In order to gain a better understanding of precise genetic changes related to physical differences observed in different strains of fish, groups of fish were experimentally tested by the following different criteria being fed diets with varied protein levels, vitamin availability, and immune response to determine if a change in gene expression of presumed response genes could be found and hence used for the monitoring of related phenotypic changes. This could then be used as an analysis method for selection and incorporated with genetic selection studies. It was found that the expression of certain genes found in muscle correlated highly with protein intake and season change. Other growth and metabolic genes showed lower levels of significance in correlating with planes of nutrition and varied upon experimental protocol. But a difference for one metabolic relevant gene was found in early tests done with animals receiving a vitamin-reduced diet. For factors relating health status after exposure to infection with microbes it was found that several factors correlated with dose of the microbe. Association of microbe dose with levels of immune health were much less pronounced when fish were tested with bacterial microbes instead of viruses. Incorporation of this work with selected of enhanced strains on cereal grain diets should allow a more precise method of analyzing specific traits during selection.

Technical Abstract: Real-time polymerase chain reaction (PCR) was used to monitor the expression of specific genes and determine how change in their expression level relates to diet, metabolism and immune response. In order to gain a better understanding of precise genetic changes related to physical differences observed in different strains of fish, groups of fish were experimentally challenged either via different planes of nutrition, vitamin availability, and pathogenic microorganisms to determine if a correlative change in gene expression of presumed response genes could be found and hence used for the monitoring of related phenotypic changes. This could then be used as an analysis method for selection and incorporated with genetic enhancement studies. It was found that the expression of certain genes such as myosin in muscle correlated highly with protein intake and season change. Other growth and metabolic genes such as insulin like growth factor and pyruvate kinase showed lower levels of significance in correlating with planes of nutrition and varied upon experimental protocol. But differences for pyruvate kinase were found in early tests done with animals receiving a vitamin-reduced diet. For factors relating immunological status after infection with microbiological pathogens it was found that several factors such as the interferon MX-1 and CD-8 correlated with dose of the viral pathogen infectious haematopoeitic necrosis virus. Association of pathogen dose with immunological expression level was much less pronounced when fish were tested with bacterial microorganisms. Incorporation of this work with genotyping of selected strains on cereal grain diets should allow a more precise method of analyzing specific traits during selection.

Last Modified: 12/22/2014
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