Turbellarian taxonomic database

Record # 23243

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Zadesenets KS, Schärer L, Rubtsov NB (2017)
New insights into the karyotype evolution of the free-living flatworm Macrostomum lignano (Platyhelminthes, Turbellaria).
Scientific Reports, Vol 7: 6066

Abstract / Notes

"The free-living flatworm Macrostomum lignano is a model organism for evolutionary and developmental biology
studies. Recently, an unusual karyotypic diversity was revealed in this species. Specifically, worms are
either 'normal' 2n = 8, or they are aneuploid with one or two additional large chromosome(s) (i.e. 2n = 9 or
2n = 10, respectively). Aneuploid worms did not show visible behavioral or morphological abnormalities and
were successful in reproduction. In this study, we generated microdissected DNA probes from chromosome 1
(further called MLI1), chromosome 2 (MLI2), and a pair of similar-sized smaller chromosomes (MLI3, MLI4). FISH
using these probes revealed that MLI1 consists of contiguous regions homologous to MLI2-MLI4, suggesting that
MLI1 arose due to the whole genome duplication and subsequent fusion of one full chromosome set into one large
metacentric chromosome. Therefore, one presumably full haploid genome was packed into MLI1, leading to hidden
tetraploidy in the M. lignano genome. The study of Macrostomum sp. 8 - a sibling species of M. lignano -
revealed that it usually has one additional pair of large chromosomes (2n = 10) showing a high homology to
MLI1, thus suggesting hidden hexaploidy in its genome. Possible evolutionary scenarios for the emergence of
the M. lignano and Macrostomum sp. 8 genomes are discussed."

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