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At least 235 records · Page 13Linked to original sources
PubMed2000

A microsatellite linkage map of rainbow trout (Oncorhynchus mykiss) characterized by large sex-specific differences in recombination rates.

We constructed a genetic linkage map for a tetraploid derivative species, the rainbow trout (Oncorhynchus mykiss), using 191 microsatellite, 3 RAPD, 7 ESMP, and 7 allozyme markers in three backcross families. The linkage map consists of 29 linkage groups with potential arm displacements in the female map due to male-specific pseudolinkage arrangements. Synteny of duplicated microsatellite markers was used to identify and confirm some previously reported pseudolinkage arrangements based upon allozyme markers. Fifteen centromeric regions (20 chromosome arms) were identified with a half-tetrad analysis using gynogenetic diploids. Female map length is approximately 10 M, but this is a large underestimate as many genotyped segments remain unassigned at a LOD threshold of 3.0. Extreme differences in female:male map distances were observed (ratio F:M, 3.25:1). Females had much lower recombination rates (0.14:1) in telomeric regions than males, while recombination rates were much higher in females within regions proximal to the centromere (F:M, 10:1). Quadrivalent formations that appear almost exclusively in males are postulated to account for the observed differences.

Animals↗
PubMed2004

A molecular linkage map of olive (Olea europaea L) based on RAPD, microsatellite, and SCAR markers.

An integrated molecular linkage map of olive (Olea europaea L.) was constructed based on randomly amplified polymorphic DNA (RAPD), sequence characterized amplified region (SCAR), and microsatellite markers using the pseudo-testcross strategy. A mapping population of 104 individuals was generated from an F1 full-sib family of a cross between 'Frantoio' and 'Kalamata'. The hybridity of the mapping population was confirmed by genetic similarity and nonmetric multidimensional scaling. Twenty-three linkage groups were mapped for 'Kalamata', covering 759 cM of the genome with 89 loci and an average distance between loci of 11.5 cM. Twenty-seven linkage groups were mapped for 'Frantoio', covering 798 cM of the genome with 92 loci and an average distance between loci of 12.3 cM. For the integrated map, 15 linkage groups covered 879 cM of the genome with 101 loci and an average distance between loci of 10.2 cM. The size of the genomic DNA was estimated to be around 3000 cM. A sequence characterized amplified region marker linked to olive peacock disease resistance was mapped to linkage group 2 of the integrated map. These maps will be the starting point for studies on the structure, evolution, and function of the olive genome. When the mapping progeny pass through their juvenile phase and assume their adult characters, mapping morphological markers and identification of quantitative trait loci for adaptive traits will be the primary targets.

Chromosome Mapping↗
PubMed1993

A linkage map of human chromosome 15 with an average resolution of 2 cM and containing 55 polymorphic microsatellites.

We have constructed a 2.0 centiMorgan (cM) resolution genetic linkage map for chromosome 15q that contains 55 polymorphic satellites and 3 RFLPs that have placed on the map with odds for order of at least 1,000:1. Genotypes from 67 polymorphic loci (64 polymorphic microsatellites) were used to construct the map. Nine genes are included in the 1,000:1 map and 37 markers have heterozygosities of at least 70%. The sex-equal map length is 128 cM and the largest genetic interval is 11 cM (15.5 cM on the female map). The female and male map lengths are 150 cM and 106 cM, respectively. The map was constructed with 'MultiMap' and is based on the CEPH reference pedigrees and includes over 12,000 new genotypes. A sub-set of 12 markers spanning the length of the linkage map were genotyped in a somatic cell hybrid panel with breakpoints that divided 15q into five segments. Cytogenetic placement agreed with the linkage positions for each of the microsatellites tested with the exception of one (ACTC) which failed to give consistent results. Ten spontaneous new mutations were identified from a subset of 42 polymorphic microsatellites (out of a total of 20,420 transmissions), giving an apparent observed spontaneous mutation rate of 5 x 10(-4) per locus. An integrated map of chromosome 15q was also constructed with the microsatellite markers described here and previously genotyped RFLP-based markers. The sex average map spans 144.7 cM with an average distance between unique map locations of 3.5 cM and a maximum intermarker distance of 11.5 cM. These genetic linkage maps can be considered baseline maps for 15q which will be useful for physical mapping and the localization of disease genes and other genes of interest.

Base Sequence↗
PubMed1996

Alignment of the PiGMaP and USDA linkage maps of porcine chromosomes 3 and 9.

The European Pig Gene Mapping Project (PiGMaP) and United States Department of Agriculture (USDA) porcine linkage maps for chromosomes 3 and 9 have been aligned by typing three USDA microsatellites from chromosome 3 and five from chromosome 9 on the PiGMaP reference families. Using the CRIMAP linkage analysis package, revised multipoint linkage maps were constructed for chromosome 3 and 9. Inclusion of these USDA markers in the multipoint analysis resulted in an increase in length of 47% and 33% respectively for these two PiGMaP linkage groups. This increase in size is mainly the result of extension of the ends of both linkage groups.

Animals↗
PubMed1996

Intensive linkage mapping in a wasp (Bracon hebetor) and a mosquito (Aedes aegypti) with single-strand conformation polymorphism analysis of random amplified polymorphic DNA markers.

The use of random amplified polymorphic DNA from the polymerase chain reaction (RAPD-PCR) allows efficient construction of saturated linkage maps. However, when analyzed by agarose gel electrophoresis, most RAPD-PCR markers segregate as dominant alleles, reducing the amount of linkage information obtained. We describe the use of single strand conformation polymorphism (SSCP) analysis of RAPD markers to generate linkage maps in a haplodiploid parasitic wasp Bracon (Habrobracon) hebetor and a diploid mosquito. Aedes aegypti. RAPD-SSCP analysis revealed segregation of codominant alleles at markers that appeared to segregate as dominant (band presence/band absence) markers or appeared invariant on agarose gels. Our SSCP protocol uses silver staining to detect DNA fractionated on large thin polyacrylamide gels and reveals more polymorphic markers than agarose gel electrophoresis. In B. hebetor, 79 markers were mapped with 12 RAPD primers in six weeks; in A aygpti, 94 markers were mapped with 10 RAPD primers in five weeks. Forty-five percent of markers segregated as codominant loci in B. hebetor, while 11% segregated as codominant loci in A. aegypti. SSCP analysis of RAPD-PCR markers offers a rapid and inexpensive means of constructing intensive linkage maps of many species.

Aedes↗
PubMed1998

A primary male autosomal linkage map of the horse genome.

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.

Animals↗
PubMed2003

Preliminary linkage map of the turkey (Meleagris gallopavo) based on microsatellite markers.

The turkey is an agriculturally important species for which, until now, there is no published genetic linkage map based on microsatellite markers--still the markers most used in the chicken and other farm animals. In order to increase the number of markers on a turkey genetic linkage map we decided to map new microsatellite sequences obtained from a GT-enriched turkey genomic library. In different chicken populations more than 35-55% of microsatellites are polymorphic. In the turkey populations tested here, 43% of all turkey primers tested were found to be polymorphic, in both commercial and wild type turkeys. Twenty linkage groups (including the Z chromosome) containing 74 markers have been established, along with 37 other unassigned markers. This map will lay the foundations for further genetic mapping and the identification of genes and quantitative trait loci in this economically important species. Genome comparisons, based on genetic maps, with related species such as the chicken would then also be possible. All primer information, polymerase chain reaction (PCR) conditions, allele sizes and genetic linkage maps can be viewed at http://roslin.thearkdb.org/. The DNA is also available on request through the Roslin Institute.

Animals↗
PubMed2002

Megagametophyte-derived linkage maps of white spruce ( Picea glauca) based on RAPD, SCAR and ESTP markers.

We have constructed linkage maps for two parents of white spruce [ Picea glauca (Moench) Voss]. Haploid megagametophytes from 92 and 96 seeds of parents M2 and 80132, respectively, were analysed with RAPD, SCAR and ESTP markers. Fragments segregating in a 1:1 Mendelian ratio were classified and mapped using MAPMAKER, GMENDEL and JOINMAP. For M2, the analysis with JOINMAP resulted in 165 loci (152 RAPDs, 3 SCARs and 10 ESTPs) mapping to 23 linkage groups and covering 2,059.4 cM(Kosambi function, K). For 80132, the analysis resulted in 144 loci (137 RAPDs, 1 SCAR and 7 ESTPs) mapping to 19 linkage groups and covering 2,007.7 cM(K). The maps covered 87 and 73% of the entire genome of parents M2 and 80132, respectively. Similar results were obtained with MAPMAKER and GMENDEL. A comparison was made between the two individual maps and 16 loci were shared between the two maps.

Journal Article↗
PubMed1997

A second-generation linkage map of the bovine genome.

We report a bovine linkage map constructed with 1236 polymorphic DNA markers and 14 erythrocyte antigens and serum proteins. The 2990-cM map consists of a sex-specific, X chromosome linkage group and 29 sex-averaged, autosomal linkage groups with an average interval size of 2.5 cM. The map contains 627 new markers and 623 previously linked markers, providing a basis for integrating the four published bovine maps. Orientation and chromosomal assignment of all the linkage groups, except BTA20 and BTA22, was provided by 88 markers that were assigned previously to chromosomes. This map provides sufficient marker density for genomic scans of populations segregating quantitative trait loci (QTL) and subsequent implementation of marker-assisted selection (MAS) mating schemes.

Animals↗
PubMed1997

Comparative linkage mapping of human chromosome 13 and bovine chromosome 12.

A comparative linkage map of human chromosome 13 and bovine chromosome 12 was constructed using eight polymorphic microsatellite markers associated with six specific genes. Linkage of these was also examined relative to five previously mapped anonymous microsatellite markers. Seven gene-linked markers were developed from bovine large-insert genomic clones containing one of five genes of interest (serotonin receptor subtype 2, fms-related tyrosine kinase, coagulation factor 10, retinoblastoma susceptibility gene, collagen type IV alpha 1), and one additional marker was developed from a microsatellite resident within an intron of the bovine dopachrome tautomerase gene. Four of these loci were previously assigned to bovine chromosome 12 by analysis of a somatic cell hybrid panel. This study provides linkage information for examining gene order in this conserved synteny group. The comparative linkage mapping results indicate that the q arm of human chromosome 13 is almost entirely conserved in bovine chromosome 12. One intrachromosomal rearrangement was detected in this linkage group relative to human, and this rearrangement was confirmed by fluorescence in situ hybridization results.

Animals↗
PubMed1990

A molecular genetic linkage map of mouse chromosome 13 anchored by the beige (bg) and satin (sa) loci.

A molecular genetic linkage map of mouse chromosome 13 was constructed using cloned DNA markers and interspecific backcross mice from two independent crosses. The map locations of Ctla-3, Dhfr, Fim-1, 4/12, Hexb, Hilda, Inhba, Lamb-1.13, Ral, Rrm2-ps3, and Tcrg were determined with respect to the beige (bg) and satin (sa) loci. The map locations of these genes confirm and extend regions of homology between mouse chromosome 13 and human chromosomes 5 and 7, and identify a region of homology between mouse chromosome 13 and human chromosome 6. The molecular genetic linkage map of chromosome 13 provides a framework for establishing linkage relationships between cloned DNA markers and known mouse mutations and for identifying homologous genes in mice and humans that may be involved in disease processes.

Animals↗
PubMed1994

Genetic linkage maps of Eucalyptus grandis and Eucalyptus urophylla using a pseudo-testcross: mapping strategy and RAPD markers.

We have used a "two-way pseudo-testcross" mapping strategy in combination with the random amplified polymorphic DNA (RAPD) assay to construct two moderate density genetic linkage maps for species of Eucalyptus. In the cross between two heterozygous individuals many single-dose RAPD markers will be heterozygous in one parent, null in the other and therefore segregate 1:1 in their F1 progeny following a testcross configuration. Meiosis and gametic segregation in each individual can be directly and efficiently analyzed using RAPD markers. We screened 305 primers of arbitrary sequence, and selected 151 to amplify a total of 558 markers. These markers were grouped at LOD 5.0, theta = 0.25, resulting in the maternal Eucalyptus grandis map having a total of 240 markers into 14 linkage groups (1552 cM) and the paternal Eucalyptus urophylla map with 251 markers in 11 linkage groups (1101 cM) (n = 11 in Eucalyptus). Framework maps ordered with a likelihood support > or = 1000:1 were assembled covering 95% of the estimated genome size in both individuals. Characterization of genome complexity of a sample of 48 mapped random amplified polymorphic DNA (RAPD) markers indicate that 53% amplify from low copy regions. These are the first reported high coverage linkage maps for any species of Eucalyptus and among the first for any hardwood tree species. We propose the combined use of RAPD markers and the pseudo-testcross configuration as a general strategy for the construction of single individual genetic linkage maps in outbred forest trees as well as in any highly heterozygous sexually reproducing living organisms. A survey of the occurrence of RAPD markers in different individuals suggests that the pseudo-testcross/RAPD mapping strategy should also be efficient at the intraspecific level and increasingly so with crosses of genetically divergent individuals. The ability to quickly construct single-tree genetic linkage maps in any forest species opens the way for a shift from the paradigm of a species index map to the heterodox proposal of constructing several maps for individual trees of a population, therefore mitigating the problem of linkage equilibrium between marker and trait loci for the application of marker assisted strategies in tree breeding.

Base Sequence↗
PubMed1994

Drawing genetic linkage maps via email.

We describe a service that permits users to draw a genetic linkage map by email. The map that is produced displays loci at their relative positions along a chromosome and can be varied in a number of ways to suit individual needs. The user sends a text file via email and receives by return email a postscript file. This file, when sent to a postscript printer, will produce a genetic linkage map.

Animals↗
PubMed2003

Construction of a mitotic linkage map of Fusarium oxysporum based on Foxy-AFLPs.

Construction of the first mitotic linkage map of the asexual fungus Fusarium oxysporum, based on a population of 32 parasexual fusion products, is reported. Molecular markers were developed using a modified AFLP technique which combines a Foxy-specific primer with standard adapter primers. The retroposon Foxy is abundantly present and highly variable in location in F. oxysporum isolates: 43% of the Foxy-AFLP markers tested appeared to be polymorphic between the strains Fol004 and Fol029. Of the 102 Foxy markers obtained, 83 segregated in a 1:1 ratio. The remaining fragments showed a skewed segregation pattern in which the Fol004 derived Foxy fragments were overrepresented. Foxy markers were observed to be clustered, suggesting that active Foxy elements may not transpose very far from their initial insertion sites, or that hotspots for insertion may exist. Linkage analysis revealed 23 linkage groups. Physical linkage between segregating markers predicted to be 20 cM apart was confirmed, indicating that the mitotic linkage map is reliable.

Cloning, Molecular↗
PubMed2000

An integrated SSR and RFLP linkage map of Sorghum bicolor (L.) Moench.

We report the development, testing, and use (for genetic mapping) of a large number of polymerase chain reaction (PCR) primer sets that amplify DNA simple sequence repeat (SSR) loci of Sorghum bicolor (L.) Moench. Most of the primer sets were developed from clones isolated from two sorghum bacterial artificial chromosome (BAC) libraries and three enriched sorghum genomic-DNA (gDNA) libraries. A few were developed from sorghum DNA sequences present in public databases. The libraries were probed with radiolabeled di- and trinucleotide oligomers, the BAC libraries with four and six oligomers, respectively, and the enriched gDNA libraries with four and three oligomers, respectively. Both types of libraries were markedly enriched for SSRs relative to a size-fractionated gDNA library studied earlier. However, only 2% of the sequenced clones obtained from the size-fractionated gDNA library lacked a SSR, whereas 13% and 17% of the sequenced clones obtained from the BAC and enriched gDNA libraries, respectively, lacked a SSR. Primer sets were produced for 313 SSR loci. Two-hundred sixty-six (85%) of the loci were amplified and 165 (53%) of the loci were found to be polymorphic in a population composed of 18 diverse sorghum lines. (AG/TC)n and (AC/TG)n repeats comprised 91% of the dinucleotide SSRs and 52% of all of the SSRs at the polymorphic loci, whereas four types of repeats comprised 66% of the trinucleotide SSRs at the loci. Primer sequences are reported for the 165 polymorphic loci and for eight monomorphic loci that have a high degree of homology to genes. Also reported are the genetic map locations of 113 novel SSR loci (including four SSR-containing gene loci) and a linkage map composed of 147 SSR loci and 323 RFLP (restriction fragment length polymorphism) loci. The number of SSR loci per linkage group ranges from 8 to 30. The SSR loci are distributed relatively evenly throughout approximately 75% of the 1406-cM linkage map, but segments of five linkage groups comprising about 25% of the map either lack or contain few SSR loci. Mapping of SSR loci isolated from BAC clones located to these segments is likely to be the most efficient method for placing SSR loci in the segments.

Alleles↗
PubMed2004

A linkage map of Atlantic salmon (Salmo salar) reveals an uncommonly large difference in recombination rate between the sexes.

A genetic linkage map of the Atlantic salmon (Salmo salar) was constructed, using 54 microsatellites and 473 amplified fragment length polymorphism (AFLP) markers. The mapping population consisted of two full-sib families within one paternal half-sib family from the Norwegian breeding population. A mapping strategy was developed that facilitated the construction of separate male and female maps, while retaining all the information contributed by the dominant AFLP markers. By using this strategy, we were able to map a significant number of the AFLP markers for which all informative offspring had two heterozygous parents; these markers then served as bridges between the male and female maps. The female map spanned 901 cM and had 33 linkage groups, while the male spanned 103 cM and had 31 linkage groups. Twenty-five linkage groups were common between the two maps. The construction of the genetic map revealed a large difference in recombination rate between females and males. The ratio of female recombination rate vs. male recombination rate was 8.26, the highest ratio reported for any vertebrate. This map constitutes the first linkage map of Atlantic salmon, one of the most important aquaculture species worldwide.

Animals↗
PubMed2004

[Linkage map construction and mapping of a dominant genic male sterility gene (Ms) in Brassica napus].

A backcross population derived from a cross between the dominant genic male sterile line Rs1046A and the double-low cultivar 'Samourai' was used for linkage map construction in Brassica napus. A linkage map with a total length of 2 646 cM was developed using 138 AFLP markers, 83 SSR markers and one morphology trait, which were distributed over 18 major linkage groups, two triplets and one linkage pair. 11.7% of the mapped markers distorted from the expected 1:1 ratio. The dominant genic male sterility gene (Ms) was mapped in LG10 and surrounded by five closely linked AFLP markers. Meanwhile,two evident marker segregation distortion regions were observed in both LG8 and LG16. The map constructed in the present study and the mapping of Ms gene are highly valuable in designing marker-assisted breeding program for the genic male sterile two-type line in Brassica napus. They are also important to map-based cloning of the Ms gene and to better understanding of the mechanism of genic male sterility at molecular level.

Brassica napus↗
PubMed2003

A linkage map of meadow fescue ( Festuca pratensis Huds.) and comparative mapping with other Poaceae species.

A genetic linkage map has been constructed for meadow fescue ( Festuca pratensis Huds.) (2n=2 x=14) using a full-sib family of a cross between a genotype from a Norwegian population (HF2) and a genotype from a Yugoslavian cultivar (B14). The two-way pseudo-testcross procedure has been used to develop separate maps for each parent, as well as a combined map. A total number of 550 loci have been mapped using homologous and heterologous RFLPs, AFLPs, isozymes and SSRs. The combined map consists of 466 markers, has a total length of 658.8 cM with an average marker density of 1.4 cM/marker. A high degree of orthology and colinearity was observed between meadow fescue and the Triticeae genome(s) for all linkage groups, and the individual linkage groups were designated 1F-7F in accordance with the orthologous Triticeae chromosomes. As expected, the meadow fescue linkage groups were highly orthologous and co-linear with Lolium, and with oat, maize and sorghum, generally in the same manner as the Triticeae chromosomes. It was shown that the evolutionary 4AL/5AL translocation, which characterises some of the Triticeae species, is not present in the meadow fescue genome. A putative insertion of a segment orthologous to Triticeae 2 at the top of 6F, similar to the rearrangement found in the wheat B and the rye R genome, was also observed. In addition, chromosome 4F is completely orthologous to rice chromosome 3 in contrast to the Triticeae where this rice chromosome is distributed over homoeologous group 4 and 5 chromosomes. The meadow fescue genome thus has a more ancestral configuration than any of the Triticeae genomes. The extended meadow fescue map reported here provides the opportunity for beneficial cross-species transfer of genetic knowledge, particularly from the complete genome sequence of rice.

Chromosome Mapping↗