Group-I introns with unusual sequences occur at three sites in nuclear 18S rRNA genes of Acanthamoeba lenticulata.
Seven of eleven isolates of Acanthamoeba lenticulata were found to have group-I introns located at one of three positions within the 18S rRNA gene. The introns are 636-721-bp long and are absent from mature rRNA. They lack open reading frames that could encode any known endonucleases. Sequences of introns from the same site in different isolates are 86.0-98.9% identical, while from different sites they are 24.2-29.8% identical. The most closely related introns from other organisms are in the 18S rRNA genes of several green algae where the 17.0-23.6% identity is mostly limited to a highly conserved core of base pairs including P, Q, R and S. Because the A. lenticulata introns only occur in one Acanthamoeba lineage, they were probably acquired after the divergence of this species.
Schroeder-Diedrich
J M
JM
Department of Molecular Genetics, The Ohio State University, 484 W 12th Avenue, Columbus, OH 43210-1292, USA.
Fuerst
P A
PA
Byers
T J
TJ
D000048:Acanthamoeba / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D016054:DNA, Protozoan / Q000737:chemistry*; D004275:DNA, Ribosomal / Q000737:chemistry; D019143:Evolution, Molecular; D007438:Introns; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid
D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S