title: Segmental paleotetraploidy revealed in sterlet (Acipenser ruthenus) genome by chromosome painting.
abstract: BACKGROUND
  Acipenseriformes take a basal position among Actinopteri and demonstrate a striking ploidy variation among species. The sterlet (Acipenser ruthenus, Linnaeus, 1758; ARUT) is a diploid 120-chromosomal sturgeon distributed in Eurasian rivers from Danube to Enisey. Despite a high commercial value and a rapid population decline in the wild, many genomic characteristics of sterlet (as well as many other sturgeon species) have not been studied.
  
  
  RESULTS
  Cell lines from different tissues of 12 sterlet specimens from Siberian populations were established following an optimized protocol. Conventional cytogenetic studies supplemented with molecular cytogenetic investigations on obtained fibroblast cell lines allowed a detailed description of sterlet karyotype and a precise localization of 18S/28S and 5S ribosomal clusters. Localization of sturgeon specific HindIII repetitive elements revealed an increased concentration in the pericentromeric region of the acrocentric ARUT14, while the total sterlet repetitive DNA fraction (C0t30) produced bright signals on subtelomeric segments of small chromosomal elements. Chromosome and region specific probes ARUT1p, 5, 6, 7, 8 as well as 14 anonymous small sized chromosomes (probes A-N) generated by microdissection were applied in chromosome painting experiments. According to hybridization patterns all painting probes were classified into two major groups: the first group (ARUT5, 6, 8 as well as microchromosome specific probes C, E, F, G, H, and I) painted only a single region each on sterlet metaphases, while probes of the second group (ARUT1p, 7 as well as microchromosome derived probes A, B, D, J, K, M, and N) marked two genomic segments each on different chromosomes. Similar results were obtained on male and female metaphases.
  
  
  CONCLUSIONS
  The sterlet genome represents a complex mosaic structure and consists of diploid and tetraploid chromosome segments. This may be regarded as a transition stage from paleotetraploid (functional diploid) to diploid genome condition. Molecular cytogenetic and genomic studies of other 120- and 240-chromosomal sturgeons are needed to reconstruct genome evolution of this vertebrate group.
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia ; Novosibirsk State University, Novosibirsk, Russia.
authors.forename: Svetlana A
authors.initials: SA
authors.lastname: Romanenko
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia.
authors.forename: Larisa S
authors.initials: LS
authors.lastname: Biltueva
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia.
authors.forename: Natalya A
authors.initials: NA
authors.lastname: Serdyukova
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia.
authors.forename: Anastasia I
authors.initials: AI
authors.lastname: Kulemzina
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia.
authors.forename: Violetta R
authors.initials: VR
authors.lastname: Beklemisheva
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia.
authors.forename: Olga L
authors.initials: OL
authors.lastname: Gladkikh
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia.
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Lemskaya
authors.affiliation: Novosibirsk Branch of the Federal State Budgetary Scientific Institution "State Scientific-and-Production Centre for Fisheries (Gosrybcenter)", Novosibirsk, Russia ; Tomsk State University, Tomsk, Russia.
authors.forename: Elena A
authors.initials: EA
authors.lastname: Interesova
authors.affiliation: Federal State Budgetary Scientific Institution "State Scientific-and-Production Centre for Fisheries (Gosrybcenter)", Tyumen, Russia.
authors.forename: Marina A
authors.initials: MA
authors.lastname: Korentovich
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia ; Novosibirsk State University, Novosibirsk, Russia.
authors.forename: Nadezhda V
authors.initials: NV
authors.lastname: Vorobieva
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia ; Novosibirsk State University, Novosibirsk, Russia.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Graphodatsky
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, Russia.
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Trifonov
keywords: Acipenseriformes; Banding; FISH; Fish cell line; Microdissection; Satellite DNA; Telomeric repeat; rRNA