• Molecules and Cells
• /
• v.22 no.3
• /
• pp.360-363
• /
• 2006

Human endogenous retroviruses (HERVs) contribute to various kinds of genomic instability via rearrangement and retrotransposition events. In the present study the formation of a new human-specific solo-LTR belonging to the HERV-H family (AP001667; chromosome 21q21) was detected by a comparative analysis of human chromosome 21 and chimpanzee chromosome 22. The solo-LTR was formed as a result of an equal homologous recombination excision event. Several evolutionary processes have occurred at this locus during primate evolution, indicating that mammalian-wide interspersed repeat (MIR) and full-length HERV-H elements integrated into hominoid genomes after the divergence of Old World monkeys and hominoids, and that the solo-LTR element was created by recombination excision of the HERV-H only in the human genome.

• The Plant Pathology Journal
• /
• v.16 no.2
• /
• pp.105-109
• /
• 2000

The Pi-b is the rice gene conferring race specific resistance to the blast fungus Magnaporthe grisea race having a corresponding avirulence gene, AVR-Pi-b. All resistant cultivars have two copies of the Pi-b gene, but susceptible cultivars have a single copy of the gene. About 1 Kbp insertion sequence was detected in the open reading frame of the Pi-b gene from the susceptible cv. Nipponbare. The nature of insertion sequence was identified as a solo long terminal repeat (LTR) of new rice Tyl-copia-like retrotransposon. LTR was widely distributed in the rice genome. Various types of different patterns of restriction fragment length polymorphism of LTR were detected in indica cultivars, whereas a single type was detected from japonica cultivars. The insertion of LTR sequence in the Pi-b gene in the susceptible cultivar suggested that retrotransposon-mediated insertional mutation might played an important role in the resistance breakdown as well as evolution of resistance genes in rice.

• The Plant Pathology Journal
• /
• v.19 no.1
• /
• pp.57-63
• /
• 2003

An insertion sequence identified as a solo long terminal repeat (LTR) of a new rice copia-like retrotransposon was detected in the ORE of the Pi-b gene from the rice cv. Nipponbare, and was designated as Osr1. Osr1 consists of a 6386 bp nucleotide sequence including 965 bp LTRs on both ends with an 82％ nucleotide sequence identity to the wheat Tarl retrotransposon on reverse transcriptase. Nucleotide divergence was noted among the individual LTRs, as well as the coding region of Osr1. Various restriction fragment length polymorphism (RFLP) of LTR were detected in indica cultivars, whereas, only a few could be detected in the japonica cultivars. The population of Osr1 is lower in the wild-type rice compared with that in the domesticated cultivars. The insertion of LTR sequence in the h-b gene in the susceptible cultivar suggested that retro-tyansposon-mediated insertional mutation might play an important role in the resistance breakdown, as well as in the evolution of resistance genes in rice.