title: Characterization of highly and moderately repetitive 500 bp Eco RI fragments from Xenopus laevis DNA.
abstract: Three different types of repetitive Eco RI fragments, which comigrate within a visible band of approximately 500 bp at gel electrophoresis of Xenopus laevis DNA Eco RI digests have been cloned and sequenced. These sequences are designated as Repetitive Eco RI Monomers: REM 1, REM 2 and REM 3. The sequences contain direct repeats, inverted repeats and palindromic elements. Genomic organization of the most abundant sequence (REM 1; 0.4% of total DNA) is that of an interspersed sequence. REM 2 (0.08%) is partly organized as an interspersed element and partly found in tandem arrangement, whereas REM 3 (0.02%) represents the tandemly repeated monomeric unit of a satellite DNA. In situ hybridization has shown that REM 1 and REM 2 sequences are found on most chromosomes, REM 1 being preferentially located on specific chromosomal loci. REM 3 is located near the centromere region of only one chromosome pair (presumably number 1). Hybridization of Northern blots from RNAs of different developmental stages revealed that REM 1, REM 2 and REM 3 sequences are transcribed and that transcription is under developmental control.
mesh_terms: D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000502:physiology; D002875:Chromosomes / Q000032:analysis; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification; D004262:DNA Restriction Enzymes; D015246:Deoxyribonuclease EcoRI; D005260:Female; D008938:Mitosis; D009693:Nucleic Acid Hybridization; D014176:Protein Biosynthesis; D012091:Repetitive Sequences, Nucleic Acid; D014981:Xenopus
chemical_list: D004247:DNA; D004262:DNA Restriction Enzymes; D015246:Deoxyribonuclease EcoRI