TY - JOUR

T1 - Chromosome evolution in the free-living flatworms

T2 - First evidence of intrachromosomal rearrangements in karyotype evolution of macrostomum lignano (platyhelminthes, macrostomida)

AU - Zadesenets, Kira S.

AU - Ershov, Nikita I.

AU - Berezikov, Eugene

AU - Rubtsov, Nikolay B.

PY - 2017/10/30

Y1 - 2017/10/30

N2 - The free-living flatworm Macrostomum lignano is a hidden tetraploid. Its genome was formed by a recent whole genome duplication followed by chromosome fusions. Its karyotype (2n = 8) consists of a pair of large chromosomes (MLI1), which contain regions of all other chromosomes, and three pairs of small metacentric chromosomes. Comparison of MLI1 with metacentrics was performed by painting with microdissected DNA probes and fluorescent in situ hybridization of unique DNA fragments. Regions of MLI1 homologous to small metacentrics appeared to be contiguous. Besides the loss of DNA repeat clusters (pericentromeric and telomeric repeats and the 5S rDNA cluster) from MLI1, the difference between small metacentrics MLI2 and MLI4 and regions homologous to them in MLI1 were revealed. Abnormal karyotypes found in the inbred DV1/10 subline were analyzed, and structurally rearranged chromosomes were described with the painting technique, suggesting the mechanism of their origin. The revealed chromosomal rearrangements generate additional diversity, opening the way toward massive loss of duplicated genes from a duplicated genome. Our findings suggest that the karyotype of M. lignano is in the early stage of genome diploidization after whole genome duplication, and further studies on M. lignano and closely related species can address many questions about karyotype evolution in animals.

AB - The free-living flatworm Macrostomum lignano is a hidden tetraploid. Its genome was formed by a recent whole genome duplication followed by chromosome fusions. Its karyotype (2n = 8) consists of a pair of large chromosomes (MLI1), which contain regions of all other chromosomes, and three pairs of small metacentric chromosomes. Comparison of MLI1 with metacentrics was performed by painting with microdissected DNA probes and fluorescent in situ hybridization of unique DNA fragments. Regions of MLI1 homologous to small metacentrics appeared to be contiguous. Besides the loss of DNA repeat clusters (pericentromeric and telomeric repeats and the 5S rDNA cluster) from MLI1, the difference between small metacentrics MLI2 and MLI4 and regions homologous to them in MLI1 were revealed. Abnormal karyotypes found in the inbred DV1/10 subline were analyzed, and structurally rearranged chromosomes were described with the painting technique, suggesting the mechanism of their origin. The revealed chromosomal rearrangements generate additional diversity, opening the way toward massive loss of duplicated genes from a duplicated genome. Our findings suggest that the karyotype of M. lignano is in the early stage of genome diploidization after whole genome duplication, and further studies on M. lignano and closely related species can address many questions about karyotype evolution in animals.

KW - Flatworms

KW - Intrachromosomal rearrangements

KW - Karyotype evolution

KW - Macrostomum lignano

KW - Whole genome duplication

KW - karyotype evolution

KW - flatworms

KW - CONSEQUENCES

KW - whole genome duplication

KW - POLYPLOIDY

KW - WHOLE-GENOME DUPLICATION

KW - intrachromosomal rearrangements

UR - http://www.scopus.com/inward/record.url?scp=85033439016&partnerID=8YFLogxK

U2 - 10.3390/genes8110298

DO - 10.3390/genes8110298

M3 - Article

C2 - 29084138

AN - SCOPUS:85033439016

VL - 8

JO - Genes

JF - Genes

SN - 2073-4425

IS - 11

M1 - 298

ER -