title: Evidence for Karyotype Polymorphism in the Free-Living Flatworm, Macrostomum lignano, a Model Organism for Evolutionary and Developmental Biology.
abstract: Over the past decade, the free-living flatworm Macrostomum lignano has been successfully used in many areas of biology, including embryology, stem cells, sexual selection, bioadhesion and aging. The increased use of this powerful laboratory model, including the establishment of genomic resources and tools, makes it essential to have a detailed description of the chromosome organization of this species, previously suggested to have a karyotype with 2n = 8 and one pair of large and three pairs of small metacentric chromosomes. We performed cytogenetic analyses for chromosomes of one commonly used inbred line of M. lignano (called DV1) and uncovered unexpected chromosome number variation in the form of aneuploidies of the largest chromosomes. These results prompted us to perform karyotypic studies in individual specimens of this and other lines of M. lignano reared under laboratory conditions, as well as in freshly field-collected specimens from different natural populations. Our analyses revealed a high frequency of aneuploids and in some cases other numerical and structural chromosome abnormalities in laboratory-reared lines of M. lignano, and some cases of aneuploidy were also found in freshly field-collected specimens. Moreover, karyological analyses were performed in specimens of three further species: Macrostomum sp. 8 (a close relative of M. lignano), M. spirale and M. hystrix. Macrostomum sp. 8 showed a karyotype that was similar to that of M. lignano, with tetrasomy for its largest chromosome being the most common karyotype, while the other two species showed a simpler karyotype that is more typical of the genus Macrostomum. These findings suggest that M. lignano and Macrostomum sp. 8 can be used as new models for studying processes of partial genome duplication in genome evolution.
authors.affiliation: Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland.|Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation.
authors.forename: Kira S
authors.identifier: http://orcid.org/0000-0001-7228-2973
authors.initials: KS
authors.lastname: Zadesenets
authors.affiliation: Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland.
authors.forename: Dita B
authors.initials: DB
authors.lastname: Vizoso
authors.affiliation: Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland.
authors.forename: Aline
authors.initials: A
authors.lastname: Schlatter
authors.affiliation: Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation.
authors.forename: Irina D
authors.initials: ID
authors.lastname: Konopatskaia
authors.affiliation: Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation.|European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Eugene
authors.identifier: http://orcid.org/0000-0002-1145-2884
authors.initials: E
authors.lastname: Berezikov
authors.affiliation: Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Schärer
authors.affiliation: Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation.|Novosibirsk State University, Novosibirsk, Russian Federation.
authors.forename: Nikolay B
authors.initials: NB
authors.lastname: Rubtsov
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002875:Chromosomes; D020732:Cytogenetic Analysis; D015342:DNA Probes / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D059785:Karyotype; D008677:Metaphase; D010986:Platyhelminths / Q000235:genetics* / Q000254:growth & development
chemical_list: D015342:DNA Probes