Hostname: page-component-848d4c4894-tn8tq Total loading time: 0 Render date: 2024-06-15T22:59:02.534Z Has data issue: false hasContentIssue false

Intra- and inter-specific variation in nuclear ribosomal internal transcribed spacer 1 of the Schistosoma japonicum species complex

Published online by Cambridge University Press:  01 April 1998

L. VAN HERWERDEN
Affiliation:
Zoology Department, James Cook University, Townsville, Queensland 4811, Australia
D. BLAIR
Affiliation:
Zoology Department, James Cook University, Townsville, Queensland 4811, Australia
T. AGATSUMA
Affiliation:
Department of Bioresource Chemistry, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido 080, Japan

Abstract

The first internal transcribed spacer (ITS1) of the nuclear ribosomal DNA repeat was sequenced for members of the Schistosoma japonicum species complex (S. malayensis, S. mekongi and 2 geographical isolates of S. japonicum). The ITS1 is composed of 3 distinct regions: the 5′ end (23 nucleotides); a tract of approximately 90–140 nucleotides, which occurs up to 7 times in tandem, the number varying even within an individual in all species investigated in this study; the 3′ region (378 nucleotides), which lacks repeats. There is size and sequence variation among copies of the ITS1 repeat within a single individual. The relative abundances of size variants of ITS1 in S. japonicum have been ascertained by hybridizing genomic digests with an ITS1 probe. Multiple repeats and intra-individual variation in numbers and abundance of these is a feature of the Asian schistosomes, but not generally of African schistosomes. Possible reasons for this difference in ITS1 between African and Asian schistosomes are discussed. The ITS1 repeat sequences described for African schistosomes are different to, and cannot be aligned with, those from the Asian species described here, whereas the remainder of the ITS1 can be aligned quite easily.

Type
Research Article
Copyright
1998 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)