TY - JOUR

T1 - New insights into the karyotype evolution of the free-living flatworm Macrostomum lignano (Platyhelminthes, Turbellaria)

AU - Zadesenets, Kira S.

AU - Schärer, Lukas

AU - Rubtsov, Nikolay B.

PY - 2017/7/20

Y1 - 2017/7/20

N2 - 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.

AB - 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.

KW - Animals

KW - Cestode Infections/parasitology

KW - Chromosomes

KW - Evolution, Molecular

KW - In Situ Hybridization, Fluorescence

KW - Karyotype

KW - Turbellaria/classification

KW - CELLS

KW - WHOLE-GENOME DUPLICATION

KW - COMMON CARP

KW - CYPRINUS-CARPIO

KW - ANEUPLOIDY

KW - CHROMOSOME

KW - GENES

KW - FISH

KW - SUBFUNCTIONALIZATION

KW - SIMULTANEOUS HERMAPHRODITE

UR - http://www.scopus.com/inward/record.url?scp=85025449752&partnerID=8YFLogxK

U2 - 10.1038/s41598-017-06498-0

DO - 10.1038/s41598-017-06498-0

M3 - Article

C2 - 28729552

AN - SCOPUS:85025449752

VL - 7

JO - Scientific Reports

JF - Scientific Reports

SN - 2045-2322

IS - 1

M1 - 6066

ER -