Theses and Dissertations


Title: TRANSLATIONAL MACHINERY OF CHANNEL CATFISH: COMPLEMENTARY DNA AND EXPRESSION OF THE COMPLETE SET OF 47 60S RIBOSOMAL PROTEINS

Name: Patterson, Andrea

Degree: MS

Chair: Zhanjiang Liu

Resides:

University: Auburn University

Location: Auburn, Alabama

Date: 2001

Pages: 68

Keywords: Channel catfish,ribosomal protein,DNA,RNA,genes

Abstract:

Ribosomal protein genes have become widely used as markers for phylogenetic studies and comparative genomics. In fish, however, they have not been available for wide evolutionary study applications although fish represent the largest group of vertebrates. Thus, we have cloned and sequenced the complete set of all 47 60S ribosomal protein cDNAs from channel catfish (Ictalurus punctatus), of which 43 included the complete protein encoding regions. This set of ribosomal protein gene sequences represents one of the most complete sets from any single organism and will aid in fish phylogenetic and comparative genomic studies. Most ribosomal protein mRNAs in channel catfish were highly conserved as compared to their mammalian counterparts, however, L4, L14, and L29 were significantly shorter in channel catfish than in mammals due to deletions in the carboxyl terminus of the corresponding genes. Two distantly related L5 cDNAs, L5a and L5b, were found in channel catfish, an unusual phenomenon in that only one type of cDNA was found for all other ribosomal protein genes. L5a was similar to L5 in other vertebrates, whereas L5b showed significant levels of divergence, suggesting independent evolution of the two L5-encoding genes. Three types of mRNAs were found for L31 derived from alternative polyadenylation. The 47 ribosomal protein genes are generally highly expressed and together account for 12.3%-14.9% of overall gene expression, depending on the tissues. Expression levels were highly variable both within a single tissue among different ribosomal protein genes, and among tissues with regard to a single ribosomal protein gene. Strong tissue preference was also observed for the expression of some ribosomal proteins. Taken together, these data suggest strong post-transcriptional regulation of ribosomal protein gene expression, particularly in consideration of the equimolar stoichiometry of their representation in ribosomes.

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