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Encyclopedia of Genetics, Genomics, Proteomics and Informatics

pp 1155-1155

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Mariner

Probably the smallest transposable element in eukaryotes (1,286 bp). It has not been observed in Drosophila melanogaster but has been detected in African species of the D. melanogaster subgroup, D. sechellia (1–2 copies), D. simulans (usually 2 copies), D. yakuba (about 4 copies), D. teissieri (10 copies), and D. mauritiana (20 to 30 copies). Mariner-like element has been detected also in soybeans.

Mariner contains 28-bp inverted terminal repeats and a single open reading frame (1,038-bp) beginning with an ATG codon at position 172 and termination with an ochre (TAA). Overlapping AATAA bases may serve as polyadenylation signal (see Fig. M20).
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Figure M20.

Mariner transposable element

The target in the untranslated leader of the w pch is 5′- TGGCGTA↓TAAACCG-3′. The arrow marks the insertion and the TATA indicate probably the target site duplication. Mariner is different from other transposable elements inasmuch as inducing a high frequency of somatic sectors (4 × 10−3) at the w pch (white peach) locus. Germline mutation is about 2 to 4 × 10−3, with about twice as high in the males than females (no sex difference in somatic mutation).

Before the transposable element was recognized, the somatic instability was attributed to the factor named Mos in chromosome 3. This element also causes dysgenesis but it does not dis-play the reciprocal difference observed in the P – M and I – R systems, however, mariner trans-mitted through the egg shows higher rates of somatic excisions. Mariner homologs occur in other species too, including humans but the (human) sequences are pseudogenic although in-crease unequal crossing over in human chromosome 17p11.2-p12. The mariner type DNA-based transposons are most common in the human genome, representing ∼1.6% of it. The mariner sequences are also expressed in Leishmania and Caenorhabditis. hybrid dysgenesis, transposable elements, Charcot-Marie-Tooth syndrome, neuropathy, HNPP, unequal crossingover, MLE, MITE, Leishmania , sleeping beauty; Hartl DL et al 1997 Annu Rev Genet 31:337; Zhang L et al 2001 Nucleic Acids Res 29:3566; Feschotte C, Wessler SR 2002 Proc Natl Acad Sci USA 99:280.

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