title: Evidence of discontinuous transcription in the trypanosomatid Crithidia fasciculata.
abstract: In an effort to exploit the advantages of Crithidia fasciculata for detailed analysis of the mechanisms of discontinuous transcription in the trypanosomatid family, we have cloned, sequenced, and characterized the mini-exon gene repeat in Crithidia and mapped the termini of its primary transcript. We find that Crithidia contains approximately 500 mini-exon genes, present almost exclusively as tandemly repeated arrays on a single chromosome. Transcripts derived from these genes are approximately 90 bases in length with heterogeneity at both the 5' and 3' ends. Primer extension experiments reveal a putative splicing intermediate. Specific inhibition of in vitro translation of Crithidia mRNAs by an oligonucleotide complementary to the mini-exon suggests that all Crithidia mRNAs contain the mini-exon at their 5' termini. Comparison of mini-exon gene sequences from various trypanosomatids reveals several regions of conservation that imply functional constraints on the transcription of mini-exon genes and the processing of their transcripts.
authors: Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
authors: A
authors: A
authors: Gabriel
authors: S S
authors: SS
authors: Sisodia
authors: D W
authors: DW
authors: Cleveland
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003421:Crithidia / Q000235:genetics*; D005091:Exons; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic