Open AccessStructural organization of the two main rDNA size classes ofAscaris lumbricoides
Author(s) -
Eduard Back,
Fritz Müller,
Heinz Tobler
Publication year - 1984
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/12.3.1313
Subject(s) - biology , ascaris lumbricoides , gene , genetics , coding region , ribosomal rna , genome , 18s ribosomal rna , genome size , zoology , helminths
The two main rDNA size classes in the genome of Ascaris lumbricoides consist of 8.8 kb and 8.4 kb long repeating units present in a quantitative ratio of roughly 10:1. They both contain the genes coding for 18 , 5.8S and 26S ribosomal RNAs. The length heterogeneity is due to a 450 bp long spacer region localized in the longer repeating unit which begins 870 bp upstream of the 5'-end 18S gene. A few additional microheterogeneities in base sequence occur at the 5'-end of the 26S gene. The 18S, 5.8S and 26S coding regions have been mapped on both the 8.8 kb and 8.4 kb repeating units and the localization of the 5'- and 3'-ends of the 18S and 26S genes has been performed by S1 protection. No intervening sequences are present in either coding region of the two main rDNA size classes.