title: Characterisation of three chromosomal ends of Leishmania major reveals transcriptional activity across arrays of reiterated and unique sequences.
abstract: The 36 chromosomes of the parasite Leishmania major range in size from 200 kb to approximately 2.5 Mb and variation between homologues seems to be restricted to the telomeric and subtelomeric regions. We have isolated three cosmids carrying the telomere hexameric repeat and assigned them to the extreme location of chromosomes 3, 7 and 20. When considering the distribution of repetitive sequences, Southern analysis of the three chromosomal ends indicated the existence of at least two classes of chromosomal extremities: one of them is composed almost exclusively of unique sequences and the other is characterised by patches of both reiterated and unique sequences. We devised a transfection-based strategy that allowed the determination of a map of transcripts in each of the regions examined. Sequencing of the chromosome 20 cosmid revealed the existence of a novel class of reiterated sequence, LST-R378, and 10 ORFs drawing a map of putative genes compatible with the map of transcripts.
authors.affiliation: Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900 14049-900, SP, Ribeirão Preto, Brazil.
authors.forename: A L
authors.initials: AL
authors.lastname: Pedrosa
authors.forename: J C
authors.initials: JC
authors.lastname: Ruiz
authors.forename: L R
authors.initials: LR
authors.lastname: Tosi
authors.forename: A K
authors.initials: AK
authors.lastname: Cruz
mesh_terms: D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D003360:Cosmids; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004706:Endodeoxyribonucleases; D005786:Gene Expression Regulation; D015698:Genomic Library; D018320:Leishmania major / Q000235:genetics*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016053:RNA, Protozoan / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D016615:Telomere / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D016054:DNA, Protozoan; D016053:RNA, Protozoan; D004706:Endodeoxyribonucleases; C038407:exonuclease Bal 31