Cytogenetical characterization of hatchery stocks and natural populations of Sea and Brown Trout from northwestern Spain

A dense brown trout (Salmo trutta) linkage map reveals recent chromosomal rearrangements in theSalmogenus and the impact of selection on linked neutral diversity

“…Our results suggest that no fusion polymorphism occurs between the two brown trout lineages. This is consistent with the lack of speciesspecific chromosomal rearrangement following speciation with the Atlantic salmon (Figure 4), and the stable chromosome number previously observed in brown trout (Hartley and Horne 1984;Martinez et al 1991;Phillips and Ráb 2001). Therefore, the lineage-averaged recombination distances provided here are probably not affected by potential interchromosomal rearrangements within the S. trutta species.…”

“…However, BT-11 was likely a metacentric chromosome based on its correspondence with the Atlantic salmon LG Ssa5 (Figure 3), and BT-17, BT-27, and BT-37 were likely acrocentric chromosomes due to single correspondences with acrocentric chromosomes of the Atlantic salmon and brook charr linkage maps (Table 1). This represents a total number of chromosome arms ranging from 88 to 90, which is lower but quite close to the 96-104 interval previously estimated in S. trutta (Martinez et al 1991;Phillips and Ráb 2001). Our assessment of chromosome type did not perfectly match the results from Gharbi et al (2006), since the three metacentric chromosomes identified here were found to be either acrocentric or undetermined in their study.…”

“…Natural brown trout populations have been intensely studied using molecular markers (e.g., Hansen et al 2000;Sanz et al 2006;Thaulow et al 2014;Berrebi 2015;Leitwein et al 2016), but previous population genetics and phylogeography studies that usually relied on a limited number of markers did not integrate linkage map information (but see Hansen and Mensberg 2009;Hansen et al 2010). The microsatellite linkage map available until now in brown trout (Gharbi et al 2006) contains $300 markers (288 microsatellites and 13 allozymes), distributed over 37 of the 40 linkage groups (LGs) expected in this species (2n = 80, Martinez et al 1991;Phillips and Ráb 2001). In order to follow the tendency toward an increasing number of markers in brown trout genetic studies (Leitwein et al 2016), a higher density linkage map is needed to increase mapping resolution and provide positional information for genome scans and association studies.…”

Basic and molecular cytogenetics in freshwater Cichlidae (Osteichthyes, Perciformes). Karyotypic conservationism and divergence

“…Among fish (PENDAS et al 1993; GALETTI }R. 1998; ALMEIDA-TOLEDO 1998;VICARI et al 2003;2005) and amphibians (ScHMID 1982), NORs generally present themselves as positive sites for the GC-specific fluorochromes such as chromomycin and mitramycin. Nevertheless, it is also known that regions stained with chromomycin/ mitramycin may not correspond to rDNA loci, but only to GC-rich heterochromatin (MARTINEZ et al 1991;ARTONI and BERTOLLO 1999). In the present case, in both Geophagus and Cichlasoma, a heterochromatic block situated directly underneath the NOR site in chromosomes 6 and 8, respectively (Figures 1, 4) is identified, showing that the ribosomal genes are not interspersed with heterochromatin but located adjacent to it, in a fashion similar to a few other fish species (ARTONI and BERTOLLO 1999).…”

The stability of telomereless chromosome fragments in adult androgenetic rainbow trout

“…Cytogenetic analysis Metaphase chromosomes were obtained according to the standard air-dry procedure (Rab and Roth, 1988) or short-term culture of blood cells (Martinez et al, 1991). To estimate the chromosome number, metaphase plates were stained with 10% Giemsa solution (Sigma, Poznan, Poland) for 10·min.…”