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United States Department of Agriculture

Agricultural Research Service

Research Project: Integrated Aquatic Animal Health Strategies

Location: Aquatic Animal Health Research

Title: Gene expression profiling of a fish parasite Ichthyophthirius multifiliis: insights into development and senescence-associated avirulence

Authors
item Abernathy, Jason -
item Xu, Dehai
item Peatman, Eric -
item Kucuktas, Huseyin -
item Klesius, Phillip
item Liu, Zhanjiang -

Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 10, 2011
Publication Date: August 16, 2011
Repository URL: http://hdl.handle.net/10113/55523
Citation: Abernathy, J., Xu, D., Peatman, E., Kucuktas, H., Klesius, P.H., Liu, Z. 2011. Gene expression profiling of a fish parasite Ichthyophthirius multifiliis: insights into development and senescence-associated avirulence. Comparative Biochemistry and Physiology. Part D 6:382-392.

Interpretive Summary: The protozoan Ichthyophthirius multifiliis (Ich) is one of the most widespread ciliate parasites of freshwater fish worldwide, causing white spot disease that leads to heavy economic losses to aquaculture and ornamental industries. Despite its economic importance, molecular studies examining fundamental processes such as life stage regulation and infectivity have been scarce. In this study, we developed an oligo microarray platform using all available I. multifiliis expressed sequence tag (EST) information as well as probes designed through comparative genomics to other protozoa. Gene expression profiling for developmental and virulence factors was conducted using this platform. For the developmental study, the microarray was used to examine gene expression profiles between the three major life stages of Ich: infective theront, parasitic trophont, and reproductive tomont. A total of 135 putative I. multifiliis genes were found to be differentially expressed among all three life-stages. Examples of differentially expressed transcripts among life stages include immobilization antigens and epiplasmin, as well as various other transcripts involved in developmental regulation and host-parasite interactions. I. multifiliis has been shown to lose infectivity at later cell divisions potentially due to cellular senescence. Therefore, the microarray was also used to explore expression of senescence-associated genes as related to the passage number of the parasite. In this regard, comparison between tomont early and late passages yielded 493 differently expressed genes; 1478 differentially expressed genes were identified between trophont early and late passages. The EST-derived oligo microarray represents a first generation array of this ciliate and provided reproducible expression data as validated by quantitative RT-PCR.

Technical Abstract: The ciliate parasite Ichthyophthirius multifiliis (Ich) infects many freshwater fish, causing white spot disease that leads to heavy economic losses to aquaculture and ornamental industries. Despite its economic importance, molecular studies examining fundamental processes such as life stage regulation and infectivity have been scarce. In this study, we developed an oligo microarray platform using all available I. multifiliis expressed sequence tag (EST) information as well as probes designed through comparative genomics to other protozoa. Gene expression profiling for developmental and virulence factors was conducted using this platform. For the developmental study, the microarray was used to examine gene expression profiles between the three major life stages of Ich: infective theront, parasitic trophont, and reproductive tomont. A total of 135 putative I. multifiliis genes were found to be differentially expressed among all three life-stages. Examples of differentially expressed transcripts among life stages include immobilization antigens and epiplasmin, as well as various other transcripts involved in developmental regulation and host-parasite interactions. I. multifiliis has been shown to lose infectivity at later cell divisions potentially due to cellular senescence. Therefore, the microarray was also used to explore expression of senescence-associated genes as related to the passage number of the parasite. In this regard, comparison between tomont early and late passages yielded 493 differently expressed genes; 1478 differentially expressed genes were identified between trophont early and late passages. The EST-derived oligo microarray represents a first generation array of this ciliate and provided reproducible expression data as validated by quantitative RT-PCR.

Last Modified: 11/23/2014
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