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United States Department of Agriculture

Agricultural Research Service

Research Project: AQUATIC ANIMAL DIAGNOSTICS, PATHOGENESIS AND APPLIED EPIDEMIOLOGY Title: Transcriptomic profiling of Ichthyophthirius multifiliis reveals polyadenylation of the large subunit ribosomal RNA

Authors
item Abernathy, Jason - AUBURN UNIVERSITY
item Xu, Dehai
item Li, Ping - AUBURN UNIVERSITY
item Klesius, Phillip
item Kucuktas, Huseyin -
item Liu, Zhanjiang - AUBURN UNIVERSITY

Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 20, 2009
Publication Date: March 18, 2009
Repository URL: http://hdl.handle.net/10113/43621
Citation: Abernathy, J.W., Xu, D., Li, P., Klesius, P.H., Kucuktas, H., Liu, Z. 2009. Transcriptomic profiling of Ichthyophthirius multifiliis reveals polyadenylation of the large subunit ribosomal RNA. Comparative Biochemistry and Physiology. Part D: Genomics and Proteomics. 4(3): 179-186.

Interpretive Summary: The ciliate teleost parasite Ichthyophthirius multifiliis (Ich) is an important fish pathogen which infects most species of fresh water fish world wide and causes high fish mortalities. Polyadenylation of eukaryotic transcripts is usually restricted to messenger RNA (mRNA). Recently polyadenylated transcripts have also been discovered in ribosomal RNA (rRNA) in some eukaryotes including humans and yeast. However, no information on polyadenylated rRNAs is available for parasite Ich. In this study, we report the discovery of polyadenylated rRNAs in parasite Ich. Analysis using multiple sequence alignments revealed four potential polyadenylation sites including three internal regions and the 3’ end of the rRNA. Further analysis using polyadenylation test and Northern blot confirmed the presence of polyadenylated rRNA in this organism. These results are critically important for understanding the functions of polyadenylation of rRNA in this organism, pathogenesis, and virulence of the parasite. This study will aid in developing methods to prevent or control this severe fish parasite.

Technical Abstract: Polyadenylation of eukaryotic transcripts is usually restricted to mRNA, whereby providing transcripts with stability from degradation by nucleases. Conversely, an RNA degradation pathway can be signaled through poly (A) tailing in prokaryotic, archeal, and organeller biology. Recently polyadenylated transcripts have also been discovered in rRNA in some eukaryotes including humans and yeast. Here we report the discovery of polyadenylated rRNAs in the ciliate teleost parasite Ichthyophthirius multifiliis, an important fish pathogen. Through large-scale analysis of ESTs, a large contig composed of the 28S rRNA with poly A tails were identified. Analysis using multiple sequence alignments revealed four potential polyadenylation sites including three internal regions and the 3’ end of the rRNA. Further analysis using a polyadenylation test, resequencing, and gene-specific PCR using primers flanking the presumed poly (a) sites confirmed the presence of polyadenylated rRNA in this organism. The extent of polyadenylated rRNA was estimated to be 1-2% of the total rRNA in the parasite. The functions of polyadenylation of rRNA in this organism is largely unknown at present, but the presence of internal polyadenylation sites, along with the presence of truncated segments of the rRNA may suggest a role of the polyadenylation in the degradation pathway, a function typical of prokaryotes, archaea, and organelles. These results are in congruence with reports of a similar phenomenon in humans and yeast.

Last Modified: 11/22/2014
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