Three retrotransposon families in the genome of Giardia lamblia: Two telomeric, one dead

AUTOR(ES)

Arkhipova, Irina R.

FONTE

The National Academy of Sciences

RESUMO

Transposable elements inhabiting eukaryotic genomes are generally regarded either as selfish DNA, which is selectively neutral to the host organism, or as parasitic DNA, deleterious to the host. Thus far, the only agreed-upon example of beneficial eukaryotic transposons is provided by Drosophila telomere-associated retrotransposons, which transpose directly to the chromosome ends and thereby protect them from degradation. This article reports the transposon content of the genome of the protozoan Giardia lamblia, one of the earliest-branching eukaryotes. A total of three non-long terminal repeat retrotransposon families have been identified, two of which are located at the ends of chromosomes, and the third one contains exclusively dead copies with multiple internal deletions, nucleotide substitutions, and frame shifts. No other reverse transcriptase- or transposase-related sequences were found. Thus, the entire genome of this protozoan, which is not known to reproduce sexually, contains only retrotransposons that are either confined to telomeric regions and possibly beneficial, or inactivated and completely nonfunctional.

Documentos Relacionados

• Chromosome-size variation in Giardia lamblia: the role of rDNA repeats.
• Spontaneous chromosome rearrangements in the protozoan Giardia lamblia: estimation of mutation rates.
• Giardia lamblia: haploid genome size determined by pulsed field gel electrophoresis is less than 12 Mb.
• Attachment of the flagellate Giardia lamblia: role of reducing agents, serum, temperature, and ionic composition.
• The cysteine-rich protein gene family of Giardia lamblia: loss of the CRP170 gene in an antigenic variant.