A Primary Male Autosomal Linkage Map of the Horse Genome

Abstract

A primary male autosomal linkage map of the domestic horse (Equus caballus) has been developed by segregation analysis of 140 genetic markers within eight half-sib families. The family material comprised four Standardbred trotters and four Icelandic horses, with a total of 263 offspring. The marker set included 121 microsatellite markers, eight protein polymorphisms, five RFLPs, three blood group polymorphisms, two PCR–RFLPs, and one single strand conformation polymorphism (SSCP). One hundred markers were arranged into 25 linkage groups, 22 of which could be assigned physically to 18 different chromosomes (ECA1, ECA2, ECA3, ECA4, ECA5, ECA6, ECA7, ECA9, ECA10, ECA11, ECA13, ECA15, ECA16, ECA18, ECA19, ECA21, ECA22, and ECA30). The average distance between linked markers was 12.6 cM and the longest linkage group measured 103 cM. The total map distance contained within linkage groups was 679 cM. If the distances covered outside the ends of linkage groups and by unlinked markers were included, it was estimated that the marker set covered at least 1500 cM, that is, at least 50% of the genome. A comparison of the relationship between genetic and physical distances in anchored linkage groups gave ratios of 0.5–0.8 cM per Mb of DNA. This would suggest that the total male recombinational distance in the horse is 2000 cM; this value is lower than that suggested by chiasma counts. The present map should provide an important framework for future genome mapping in the horse.

The First-Generation Whole-Genome Radiation Hybrid Map in the Horse Identifies Conserved Segments in Human and Mouse Genomes

“…Significant strides have since been made in expanding the gene map of the horse (Equus caballus; ECA, reviewed in Chowdhary and Raudsepp 2000). Currently ∼1200 markers have been mapped/assigned to various equine chromosomes using approaches such as synteny analysis (Caetano et al 1999a,b;Shiue et al 1999), genetic linkage mapping (Lindgren et al 1998;Guérin et al 1999Guérin et al , 2003Swinburne et al 2000a), and fluorescent in situ hybridization (FISH; e.g., Raudsepp et al 1999;Godard et al 2000;Lear et al 2001;Mariat et al 2001;Milenkovic et al 2002). Among the recent prominent developments are the generation of preliminary radiation hybrid (RH) maps for chromosomes ECA1 and ECA10 (Kiguwa et al 2000) and RH and comparative maps for some of the other equine chromosomes Raudsepp et al 2002).…”

“…A distribution of the number of anchor markers by chromosome is presented in Table 2. The remaining 13 RH groups were placed using available genetic linkage information (Lindgren et al 1998;Swinburne et al 2000a;Guérin et al 2003) and the RH2pt data for end markers with markers in the adjacent RH groups (Fig. 1, enclosed poster; see linkage groups with white bars).…”

A Microsatellite Linkage Map of Barramundi, Lates calcarifer

“…Because of their high abundance and polymorphism as well as the ease of scoring by PCR, microsatellites have been extensively used in the construction of linkage maps (Murray et al 1994;Kappes et al 1997;Lindgren et al 1998). Linkage maps based on microsatellites in fish are relatively scarce (Gates et al 1999;Chistiakov et al 2005;Lee et al 2005).…”

Mapping the horse genome and its impact on equine genomics for identification of genes for monogenic and complex traits – a review

“…GODARD et al (1997) assigned 36 new horse microsatellites, 11 of them from plasmid libraries and 25 from a cosmid library. The first equine linkage map included 140 markers (LINDGREN et al, 1998) and a more extensive linkage map consisted of 161 loci in 29 linkage groups for 26 autosomes . The first map covering all autosomes and the sexchromosomes using 353 microsatellite-markers was generated by SWINBURNE et al (2000).…”