Malgorzata Jankun

Ribosomal genes in Coregonid fishes (Coregonus lavaretus, C. albula and C. peled) (Salmonidae): single and multiple nucleolus organizer regions

Major rDNA loci, i.e. nucleolus-organizing regions (NORs), were assigned using chromomycin-A3 (CMA3) staining followed by sequential silver (Ag) staining and in situ hybridization (ISH) with a rDNA probe to the chromosomes of the European whitefish (Coregonus lavaretus), the peled (Coregonus peled) and the vendace (Coregonus albula), three closely related coregonine salmonid fishes. One pair of NOR-bearing chromosomes was found in the peled karyotype. Multichromosomal, but stable, locations of rDNA sites on three pairs of chromosomes were observed in the European whitefish karyotype. Multichromosomal polymorphic locations, both in site and number, were observed in the karyotype of the vendace. Several Ag-, CMA3- and ISH-positive regions were found which defined up to seven cytotypes of five NOR-bearing chromosomes. All positive Ag-NORs detected corresponded both to rDNA-ISH- and CMA3-positive signals, which suggests extensive structural polymorphism in the locations of rDNA sites. Stable NOR sites were found at the same location on both homologous elements of the chromosome no. 9 in all individuals, while the remaining NORs were quite variable between individuals, and often present in heterozygous condition. The apparently similar and parallel evolutionary rDNA differentiation patterns in the subfamilies Coregoninae and Salmoninae (family Salmonidae) are observed and discussed.

A Population Analysis of the Structure and Variability of NOR in Salmo Trutta by Ag, CMA3 and ISH

An analysis of the variation in the number and location of rDNA genes has been carried out in two populations of brown trout (Salmo trutta) from Poland by using Ag and CMA3-staining, and rDNA in situ hybridisation. We observed an interindividual variation in arm number with NF = 100, 101, and 102. This variation was connected with the size polymorphism of the short (NOR-bearing) arm of the chromosome pair 11. The population studied showed a multichromosomal distribution of active NORs. Atypical Ag-NORs consisted of rDNA genes, as evidenced by rDNA-ISH. In addition to individuals with standard NORs, specimens with extra NORs as well as others with only one active NOR and single interphase nucleolus were observed.

Chromosomal Characteristics of rDNA in European Grayling Thymallus thymallus (Salmonidae)

The chromosomal characteristics, locations and variations of two classes of ribosomal DNA (5S and 18S) were studied in European grayling karyotype (Thymallus thymallus, Salmonidae). Major rDNA sites as revealed by sequential CMA3/Ag staining and confirmed by in situ hybridization with a 18S rDNA probe were situated in two loci and were found to be polymorphic in size and displaying several distinct forms. The 5S rDNA was located by PRINS on three pairs of subtelocentric chromosomes, additional minor signal was present at the centromere of one metacentric element. 5S sites were not associated with NORs. The dosage compensation mechanism was proposed as an explanation of high frequency of lethal rDNA-deleted forms of the NOR-bearing chromosomes. Double variable pattern in the number and location of NORs supported the bi-directional evolution of salmonid rDNA loci.

Chromosome polymorphism in Salmo trutta morpha lacustris from Poland, Wdzydze Lake population: Variation in the short arm length of chromosome eleven

Abstract: A population of Salmo trutta m. lacustris from Lake Wdzydze was karyotyped using C-banding and fluorochrome staining techniques. The chromosome number was 2n = 80, and the chromosome arm number (NF) was 100-102. Variation in the size of the short arm of chromosome pair eleven was observed: the presence of heterochromatin on this arm was confirmed by C-banding and DAPI staining. Chromomycin A3 and silver stainings revealed the presence of nucleolar organizer region (NOR) on this arm. Additional CMA3-positive regions were observed on two acrocentric chromosomes. The polymorphism of chromosome pair eleven observed in Salmo trutta m. lacustris probably resulted from deletions or multiplications of heterochromatin connected to NOR. The karyotype and observed polymorphism of the NOR-bearing chromosome pair was the same as observed in other ecological forms of Salmo trutta.

Pericentromeric location of the telomeric DNA sequences on the European grayling chromosomes

AbstractThe chromosomal characteristics, locations and variations of the C-band positive heterochromatin and telomeric DNA sequences were studied in the European grayling karyotype (Thymallus thymallus, Salmonidae) using conventional C-banding, endonucleases digestion banding, silver nitrate (AgNO3), chromomycin A3 and 4′,6-diamidino-2-phenylindole staining techniques as well as fluorescence in situ hybridization (FISH) and primed in situ labelling. Original data on the chromosomal distribution of segments resistant to AluI restriction endonuclease and identification of the C-banded heterochromatin presented here have been used to characterize the grayling karyotype polymorphism. Structural and length polymorphism of the chromosome 21 showing a conspicuous heterochromatin block adjacent to the centromere seems to be the result of the deletion and inversion. Two pairs of nuclear organizer regions (NOR)-bearing chromosomes were found to be polymorphic in size and displaying several distinct forms. FISH with telomeric peptide nucleic acid probe enabled recognition of the conservative telomeric DNA sequences. The karyotype of the thymallid fish is thought to experienced numerous pericentric inversions and internal telomeric sites (ITSs) observed at the pericentromeric regions of the six European grayling metacentric chromosomes are likely relics of the these rearrangements. None of the ITS sites matched either chromosome 21 or NOR bearing chromosomes.

Localization of 5S rRNA loci in three coregonid species (Salmonidae).

In the present study the chromosome distribution of the 5S rDNA loci and its relation to the major rDNA genes were investigated in three Coregonid species (Salmonidae): Coregonus lavaretus, Coregonus peled and Coregonus albula, a family which has experienced large karyotype rearrangements along its evolution starting from a tetraploid ancestor. 5S PRINS/CMA3 sequential staining together with previous data enabled us to locate 5S rRNA genes and nucleolar organizer regions (NORs) in the three species analyzed. PRINS revealed the 5S rDNA cluster at the distal part of the long arm of a similar submetacentric chromosome pair in the three species. Our data indicate that 5S rDNA clusters have probably conserved chromosomal location in the genus Coregonus, whereas 45S rDNA (NOR) sites are clearly differentiated, from a single locus in C. peled, to multiple loci in C. lavaretus and highly polymorphic multichromosomal location in C. albula.

rRNA genes map to chromosomes 10, 11 and 12 in European whitefish (Coregonus lavaretus) and to chromosomes 1, 5, 9 and 10 in vendace (Coregonus albula)

Previous NOR studies with Agand CMA3staining has demonstrated a multichromosomal position of NORs in the karyotypes of Coregonus albula (vendace) [1] and Coregonus lavaretus (European white¢sh) [2]. Chromosome preparations were obtained according to Jankun et al. [3]. The plasmid pB180, which includes a long fragment of the human rDNA transcription unit, namely the promoter and most of the 18S gene, was used as a probe for ISH. rDNA probe was labelled with biotin 16-dUTP using a commercially available Biotin Nick Translation Mix (Boehringer). The hybridization procedure was performed as described by Kerstens et al. [4] with slight modi¢cations. Chromosomes were counterstained with Harris haematoxylin. In-situ hybridization in European white¢sh chromosomes showed six signals on three small subtelocentric chromosomes (pairs 10, 11 and 12, according to Jankun et al. [3]; Figure 1a), the main one on pair 10. In vendace, the main signal was found on chromosome pair 9, although minor signals were detected on one or both homologues from different chromosome pairs (pairs 1, 5, 10, according to Jankun et al. [1]; Figure 1b). This study was supported by the project No. 5 P06D 024 17 ¢nanced by KBN for M.J., the project S5045011 by CAS for P.R. and M.R.

Genetic characterization of Polish cultured brook trout, Salvelinus fontinalis (Mitchill), based on microsatellite DNA analysis

Genetic characterization of Polish cultured brook trout, Salvelinus fontinalis (Mitchill), based on microsatellite DNA analysis The genetic variability of two farmed strains of brook trout, Salvelinus fontinalis (Mitchill), was examined using six microsatellite DNA loci. The objective of the present study was to evaluate locus-specific genetic markers in brook trout strains cultured in Poland and to assess their levels of genetic diversity. The average number of alleles at all loci in the studied stocks differed between the two groups: 2.20 in the Rutki strain and 7.20 in the Canada strain. For the microsatellites examined, the number of alleles per locus ranged from 1 (locus Ssa-171 in the Canada strain) to 24 (locus Sfo-292 in the Canada strain). The results suggested that the Canada strain had higher gene diversity than the Rutki strain. The molecular analysis described in the present study will be useful for monitoring long-term genetic variation and for the identification of suitable parents for the development of stocks with suitable gene diversity in cultured Polish brook trout. Charakterystyka genetyczna pstrąga źródlanego (Salvelinus fontinalis Mitchill) hodowanego w Polsce przy zastosowaniu mikrosatelitarnych fragmentów DNA Przedmiotem opisywanych badań była analiza genetyczna dwóch stad pstrąga źródlanego Salvelinus fontinalis. Głównym celem badań było zidentyfikowanie alleli w wybranych loci mikrosatelitarnego DNA, charakterystycznych dla dwóch stad pstrąga źródlanego, pochodzących z Zakładu Hodowli Ryb Łososiowatych w Rutkach Instytutu Rybactwa Śródlądowego w Olsztynie. Średnia liczba alleli w analizowanych loci u badanych ryb wynosiła od 2,20 (stado Rutki) do 7,20 (stado Canada). Liczba alleli w badanych loci wynosiła od 1 (locus Ssa-171 dla stada Canada) do 24 (locus Sfo-292 dla stada Canada). W wyniku przeprowadzonych analiz stwierdzono, iż stado Canada charakteryzowało się wyższą zmiennością genetyczną w porównaniu do stada Rutki. Opisaną metodę przy zastosowaniu markerów mikrosatelitarnego DNA można wykorzystać do monitoringu genetycznego w trakcie prowadzenia prac hodowlanych.

Chromosome number and erythrocyte nuclei length in triploid Siberian sturgeon Acipenser baeri Brandt

Abstract The chromosome preparation and erythrocyte nuclei measurements were used to determine the ploidy in Siberian sturgeon (Acipenser baeri Brandt): normal and after heat shock. The results show that the increase of chromosome number is highly correlated to increase of erythrocytes major axis.

Cytogenetic Characterization of Sea Trout (Salmo trutta) from Poland

Cytogenetic analysis of two local populations of sea trout (Salmo trutta) revealed a diploid chromosome number (2n) of 80 and a diploid chromosome arm number (NF) of 102. Two heteromorphic chromosome pairs were identified, based on Cbanding and DAPIand CMA3-staining: NOR-bearing pair 11 and metacentric pair 6. The study was designed to search for chromosome markers enabling separation of fish from one of the Pomeranian rivers (Slupia River) compared to those from the Vistula River. Frequencies of the heteromorphic chromosome pairs identified genetic differences between the two groups.