A Microsatellite Genetic Linkage Map for XiphophorusSequence data from this article have been deposited with the EMBL/GenBank Data Libraries under accession nos. AY258640, AY258896.

Abstract

Interspecies hybrids between distinct species of the genus Xiphophorus are often used in varied research investigations to identify genomic regions associated with the inheritance of complex traits. There are 24 described Xiphophorus species and a greater number of pedigreed strains; thus, the number of potential interspecies hybrid cross combinations is quite large. Previously, select Xiphophorus experimental crosses have been shown to exhibit differing characteristics between parental species and among the hybrid fishes derived from crossing them, such as widely differing susceptibilities to chemical or physical agents. For instance, genomic regions harboring tumor suppressor and oncogenes have been identified via linkage association of these loci with a small set of established genetic markers. The power of this experimental strategy is related to the number of genetic markers available in the Xiphophorus interspecies cross of interest. Thus, we have undertaken the task of expanding the suite of easily scored markers by characterization of Xiphophorus microsatellite sequences. Using a cross between Xiphophorus maculatus and X. andersi, we report a linkage map predominantly composed of microsatellite markers. All 24 acrocentric chromosome sets of Xiphophorus are represented in the assembled linkage map with an average intergenomic distance of 7.5 cM. Since both male and female F 1 hybrids were used to produce backcross progeny, these recombination rates were compared between "male" and "female" maps. Although several genomic regions exhibit differences in map length, male-and female-derived maps are similar. Thus Xiphophorus, in contrast to zebrafish, Danio rerio, and several other vertebrate species, does not show sex-specific differences in recombination. The microsatellite markers we report can be easily adapted to any Xiphophorus interspecies and some intraspecies crosses, and thus provide a means to directly compare results derived from independent experiments.

A Genetic Linkage Map of the Hermaphrodite Teleost Fish Sparus aurata L.

“…In the Japanese flounder, the male sex has an unusually high recombination rate, which is 7.4 times higher than that in females (Coimbra et al 2003). In other fish species, such as the swordtail (Walter et al 2004), where ZW as well as XY systems have been reported, and tilapia (Lee et al 2005), where a major locus for sex determination seems to be present, no significant difference is found between the overall lengths of male and female maps, although sex-specific recombination rates appear to vary across linkage groups and within the same linkage group. A similar situation is observed in the gilthead sea bream.…”

Marine Organism Cell Biology and Regulatory Sequence Discoveryin Comparative Functional Genomics

“…Membrane transporters that are the sites of action of diuretic drugs were first cloned from specialized organs in marine species (Gamba et al 1993;Xu et al 1994). Mutagenesis studies in bony fish generated a spectrum of biologically relevant and distinct phenotypes (Naruse et al 2004;Walter et al 2004). Large-scale genetic screens produced more than 500 zebrafish mutants, many with phenotypes similar to human disorders (Dooley and Zon 2000).…”

A RAD-Tag Genetic Map for the Platyfish (Xiphophorus maculatus) Reveals Mechanisms of Karyotype Evolution Among Teleost Fish

“…We constructed the meiotic map from a backcross-mapping panel generated by crossing female platyfish (X. maculatus) to male swordtail (X. hellerii) using swordtail as the recurring parent. The platyfish genetic map contains 16,114 polymorphic markers scored on 267 individuals localized along the 24 platyfish chromosomes (Walter et al 2004;Schartl et al 2013). Because the platyfish genetic map utilized polymorphisms detected by single nucleotide polymorphisms (SNPs) present in sequence tags adjacent to restriction enzyme cut sites (RAD-tags) (Miller et al 2007;Baird et al 2008;Amores et al 2011), the sequences in mapped markers can be associated readily to contigs in the genome sequence assembly .…”