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Construction of a high-throughput rat genetic mapping system with 466 arbitrarily primed-representational difference analysis markers.

Linkage mapping of quantitative trait loci (QTLs) requires genetic markers that can be efficiently genotyped for a large number of individuals. To isolate genetic markers suitable for this purpose, we previously established the arbitrarily primed RDA (AP-RDA) method. Dot-blotting AP-PCR products (AP-amplicons) onto filters at a high density and hybridization of the filters with the AP-RDA markers made it possible to genotype a large number of individuals simultaneously for multiple loci. In this study, by using 25 primers or primer combinations, we isolated a total of 419 AP-RDA markers by subtracting the AP-amplicon of BUF rats from that of ACI rats, and vice versa. By combining 47 previously isolated markers, a rat genetic map was drawn with 466 AP-RDA markers. Between two given strains of rats other than ACI and BUF, the average informativeness of the markers was 38%. As for the intercross of ACI and BUF rats, 12 selected primers served to genotype 259 loci. In addition, the amounts and quality of genomic DNA to be used for AP-PCR were examined to guarantee reliable genotyping. Now, initial genome scanning of the rat for linkage analysis can be performed efficiently using this mapping system with AP-RDA markers.

Animals↗

Genetic mapping of ecotropic murine leukemia virus-inducing loci in six inbred strains.

Mendelian segregation analysis was used to map chromosomal genes for the induction of endogenous N- and B-tropic ecotropic retroviruses (V loci) in high and low leukemic mouse strains. Patterns of virus expression were determined for mice of various inbred strains, congenic lines carrying single V loci, and the linkage testing stocks used in mapping studies. Segregation analysis resulted in the genetic mapping of V loci from six inbred strains to five mouse chromosomes. The V locus of A/J was mapped to chromosome 5 and shown to be allelic with that of BALB/cJ and C3H/HeJ (Cv); this suggests that Cv-represents a stable ancestral V locus present in Bagg albino stocks before the separation of inbred lines. The single, poorly inducible V locus of C57BL/10J and one of the four high virus loci of C58/Lw were mapped to the same region of chromosome 8 and may represent an allelic pair with different patterns of expression. An N-tropic V locus of the SEA/GnJ mouse was mapped to chromosome 9, and one of the three V loci of C3H/FgLw was mapped to chromosome 7. The endogenous B-tropic virus of B10.BR/SgLi was mapped to chromosome 11. These studies provide further evidence that endogenous ecotropic V loci are present at different chromosomal sites in unrelated mouse strains and emphasize the role of germ line reinfections in the generation of this diversity.

Alleles↗

Genetic map location of the Escherichia coli dnaG gene.

The dnaG locus of Escherichia coli K-12 has been mapped at about 60 min on the genetic map by three-factor crosses using P1 transduction. In crosses selecting for dnaG+, the cotransduction frequency with the tolC marker is 15% and that with the uxaC marker is 49%. The gene order is tolC dnaG uxaC.

Chromosome Mapping↗

Cytogenetic assignment of 53 microsatellites from the USDA-MARC porcine genetic map.

This study provides 53 new fluorescent in situ hybridization cytogenetic assignments for microsatellite markers linked on the swine genetic map. Forty microsatellites are physically assigned for the first time. The chromosomal locations of eight markers were either confirmed or refined, while five loci were assigned to locations different from those given in previous reports. Markers were selected to provide physical anchors based on their presumed proximity to centromeres or telomeres and at approximately 30 cM intervals across the genetic map. The number of physical anchors for pig (SSC) chromosomes 8, 15, and 18 linkage groups was significantly improved. Centromeric regions were localized to areas less than 10 cM for SSC 1, 2, 3, 6, 7, 8, and 9. Although the recombination rate was generally higher across small biarmed chromosomes and lowest for large acrocentric chromosomes, two regions with particularly low (1q2.1-->q2.9 and 13q2.3-->q4.1) and three regions with extremely high (5p1.5-->p1.2, 6p1.4-->p1.3, and 12p1.5-->p1.4) rates of recombination were detected. These assignments represent an overall 10% increase in the number of physically assigned markers in Sus scrofa and more than a 20% increase in the number of Type II loci assigned to the pig cytogenetic map.

Animals↗

Development of the genetic map of the yeast Saccharomycopsis lipolytica.

Tetrad and random spore analyses have been used to further develop the genetic map of Saccharomycopsis lipolytica. Mutations in 23 new nuclear genes have been isolated. Eight genes have been located on linkage fragment 1, 4 on fragment 2, 2 on fragment 5 and 3 on fragment 6. Linkage fragments 3 and 4 have been shown to be linked, and this fragment now contains 12 markers. A tentative map of the linkage fragments 1 and 3 is presented (Fig. 1). Markers exhibiting possible centromere linkage have been identified. Interference estimates suggest that there is little interference in S. lipolytica.

Ascomycota↗

A comparison of genetic maps constructed from haploid and BC1 mapping populations from the same crossing between Gossypium hirsutum L. and Gossypium barbadense L.

Simple sequence repeat (SSR) genetic maps have been separately constructed based on doubled haploid (DH) and (or) haploid and BC1 populations from the same cross between Gossypium hirsutum L. 'TM-1' and Gossypium barbadense L. 'Hai7124'. The BC1 population was produced by pollinating individual plants of the 'TM-1' x 'Hai7124' F1 with 'TM-1', whereas the DH and (or) haploid population developed from the offspring of Vsg x ('TM-1' x 'Hai7124'). Vsg is a virescently marked semigamy line of Gossypium barbadense L. Pima. The BC1 map included 34 linkage groups with an average distance between markers of 9.80 cM (Kosambi, K) and covered 4331.2 cM (K) or approximately 78.7% of the tetraploid cotton genome constructed using 440 SSR and 2 morphological marker genes. Among them, 26 were assigned to 20 chromosomes, 7 to A or D subgenomes, and 1 was unassigned. The haploid map comprised 444 SSR markers mapped to 40 linkage groups with an average distance of 7.35 cM (K) between markers, covering 3262.9 cM (K) or approximately 60.0% of the tetraploid genome. Twenty-nine linkage groups were assigned to all 19 identified chromosomes, 10 to A or D subgenomes, and 1 was unassigned. Fairly good collinearity of marker order was observed along most of the chromosomes or linkage groups. Significant differences in recombination between maps was observed at the chromosomal and genomic level and possible reasons were discussed. Map comparison and combined data provided an essential basis for further mapping of interested genes and QTLs and for studies of diversity, population structure, and phylogeny in Gossypium species.

Chromosome Mapping↗

[Genetic mapping in relation to disease susceptibility].

The search for chromosome regions that potentially harbour susceptibility genes for diseases by investigating the inheritance of disease and DNA markers in groups of patients is the initial step in the identification of the specific genes involved. The identification of genes involved in disease susceptibility is one of the main research strategies for unravelling the etiology and pathophysiology of many common diseases. However, such diseases often have a complex etiology which makes the genetic mapping of the involved disease genes very difficult. Fortunately, a number of different methods exist for genetic mapping of disease genes.

Chromosome Mapping↗

Genetic map of the human pseudoautosomal region reveals a high rate of recombination in female meiosis at the Xp telomere.

This paper describes the genetic map of the pseudoautosomal region bounded by the telomere of the short arms of the X and Y chromosomes. In males, meiotic exchange on Xp/Yp is confined to this region, leading to highly elevated recombination rates. The map was constructed using 11 pseudoautosomal probes (six of which are new) and typing individuals from 38 CEPH families. All markers have been physically mapped, thus providing the opportunity to compare genetic distance to physical distance through all intervals of the map. This comparison reveals an unexpected high rate of recombination in female meiosis between loci DXYS20 and DXYS78, within 20-80 kb from the telomere. Within this telomere-adjacent region no differences in male and female recombination rates are seen. Furthermore, data from this genetic map support the hypothesis of a linear gradient of recombination across most of the region in male meiosis and provide densely spaced anchor points for linkage studies especially in the telomeric portion of the pseudoautosomal region.

Alleles↗

TraitMap: an XML-based genetic-map database combining multigenic loci and biomolecular networks.

MOTIVATION: Most ordinary traits are well described by multiple measurable parameters. Thus, in the course of elucidating the genes responsible for a given trait, it is necessary to conduct and integrate the genetic mapping of each parameter. However, the integration of multiple mapping results from different publications is prevented by the fact that they are conventionally published and accumulated in printed forms or graphics which are difficult for computers to reuse for further analyses. RESULTS: We have defined an XML-based schema as a container of genetic mapping results, and created a database named TraitMap containing curator-checked data records based on published papers of mapping results in Homosapiens, Mus musculus, and Arabidopsis thaliana. TraitMap is the first database of mapping charts in genetics, and is integrated in a web-based retrieval framework: termed Genome <--> Phenome Superhighway (GPS) system, where it is possible to combine and visualize multiple mapping records in a two-dimensional display. Since most traits are regulated by multiple genes, the system associates every combination of genetic loci to biomolecular networks, and thus helps us to estimate molecular-level candidate networks responsible for a given trait. It is demonstrated that a combined analysis of two diabetes-related traits (susceptibility to insulin resistance and non-HDL cholesterol level) suggests that molecular-level relationships such as the interaction among leptin receptor (Lepr), peroxisome proliferators-activated receptor-gamma (Pparg) and insulin receptor substrate 1 (Irs1), are candidate causal networks affecting the traits in a multigenic manner. AVAILABILITY: TraitMap database and GPS are accessible at http://omicspace.riken.jp/gps/

Chromosome Mapping↗

Comparison of a Brassica oleracea genetic map with the genome of Arabidopsis thaliana.

Brassica oleracea is closely related to the model plant, Arabidopsis thaliana. Despite this relationship, it has been difficult to both identify the most closely related segments between the genomes and determine the degree of genome replication within B. oleracea relative to A. thaliana. These difficulties have arisen in part because both species have replicated genomes, and the criteria used to identify orthologous regions between the genomes are often ambiguous. In this report, we compare the positions of sequenced Brassica loci with a known position on a B. oleracea genetic map to the positions of their putative orthologs within the A. thaliana genome. We use explicit criteria to distinguish orthologous from paralogous loci. In addition, we develop a conservative algorithm to identify collinear loci between the genomes and a permutation test to evaluate the significance of these regions. The algorithm identified 34 significant A. thaliana regions that are collinear with >28% of the B. oleracea genetic map. These regions have a mean of 3.3 markers spanning 2.1 Mbp of the A. thaliana genome and 2.5 cM of the B. oleracea genetic map. Our findings are consistent with the hypothesis that the B. oleracea genome has been highly rearranged since divergence from A. thaliana, likely as a result of polyploidization.

Arabidopsis↗

Physical and genetic maps of the deafwaddler region on distal mouse Chr 6.

The deafwaddler (dfw) mutation, displaying motor ataxia and profound deafness, arose spontaneously in a C3H/HeJ colony and was mapped previously to distal mouse Chr 6. In this study, a high-resolution genetic map was generated by positioning 10 microsatellite markers and 5 known genes on a 968-meioses intersubspecific backcross segregating for dfw [(CAST/Ei(-)+/+ x C3HeB/ FeJ-dfw/dfw) x C3HeB/FeJ-dfw/dfw], giving the following marker order and sex-averaged distances: D6Mit64-(0.10 + 0.10 cM)-Pang-(1.24 + 0.36 cM)-Itpr1-(0.62 + 0.25 cM)-D6Mit108-(0.52 + 0.23 cM)-D6Mit54-(0.21 + 0.15 cM)-D6Mit23, D6Mit107, D6Mit328-(0.72 + 0.27 cM)-D6Mit11-(0.21 + 0.15 cM)-dfw-(0.93 + 0.31 cM)-Gat4, D6Mit55-(0.10 + 0.10 cM)-D6Mit63-(0.31 + 0.18 cM)-Syn2-(0.62 + 0.25 cM)-D6Mit44 (Rho). Female and male genetic maps are similar immediately surrounding the dfw locus, but show marked differences in other areas. A yeast artificial chromosome-based physical map suggests that the closest markers flanking the dfw locus, D6Mit11 (proximal) and Gat4, D6Mit55 (distal), are contained within 650-950 kb. The human homologues of the flanking loci Itpr1 (proximal) and Syn2 (distal) map to chromosome 3p25-p26, suggesting that the human homologue of the dfw gene is located within this same region.

Animals↗

Recombinants between temperature-sensitive mutants of rauscher murine leukemia virus and BALB:virus-2: genetic mapping of the Rauscher murine leukemia virus genome.

Recombinant viruses were generated in tissue culture between Rauscher murine leukemia virus (MuLV) temperature-sensitive (ts) mutants restricted at different steps in virus replication and a mouse endogenous xenotropic virus, BALB:virus-2. Mutants used included ts 28, a late mutant which releases noninfectious viruses at 39 degrees C, and ts 29, a double mutant with a ts lesion in its reverse transcriptase and a late block affecting virus budding. Immunological typing of the translational products of clonal recombinant viruses made it possible to establish their partial genetic maps and localize regions of the viral genome affected by different ts lesions. Recombinants involving Rauscher MuLV ts 28 invariably contained BALB-virus-2 p15, p12, and p30 proteins, localizing the late defect in replication by this mutant to the 5' moiety of the viral gag gene. All ts 29-derived recombinants contained the entire BALB:virus-2 gag and pol genes. Substitution of the pol gene is in agreement with the reported thermolability of Rauscher MuLV ts 29 reverse transcriptase (Tronick et al., J. Virol. 16:1476-1482, 1975). Substitution of the gag gene suggests that internal structural proteins are actively involved in the virus budding processing. Rauscher MuLV recombinants were used to establish the genetic map of the Rauscher MuLV genome by T1 oligonucleotide fingerprinting analysis. Detection of Rauscher MuLV T1 oligonucleotides in representative recombinant viruses, whose protein phenotypes were established by immunological techniques, permitted their assignment to specific regions of the viral genome. The genetic map of Rauscher MuLV generated in these studies should be useful for identifying and characterizing the viral gene(s) involved in leukemogenesis.

Animals↗

Comparing EST-based genetic maps between Pinus sylvestris and Pinus taeda.

A genetic map of Pinus sylvestris was constructed using ESTP (expressed sequence tag polymorphism) markers and other gene-based markers, AFLP markers and microsatellites. Part of the ESTP markers (40) were developed and mapped earlier in Pinus taeda, and additional markers were generated based on P. sylvestris sequences or sequences from other pine species. The mapping in P. sylvestris was based on 94 F(1) progeny from a cross between plus-tree parents E635C and E1101. AFLP framework maps for the parent trees were first constructed. The ESTP and other gene sequence-based markers were added to the framework maps, as well as five published microsatellite loci. The separate maps were then integrated with the aid of AFLPs segregating in both trees (dominant segregation ratios 3:1) as well as gene markers and microsatellites segregating in both parent trees (segregation ratios 1:1:1:1 or 1:2:1). The integrated map consisted of 12 groups corresponding to the P. taeda linkage groups, and additionally three and six smaller groups for E1101 and E635C, respectively. The number of framework AFLP markers in the integrated map is altogether 194 and the number of gene markers 61. The total length of the integrated map was 1,314 cM. The set of markers developed for P. sylvestris was also added to existing maps of two P. taeda pedigrees. Starting with a mapped marker from one pedigree in the source species resulted in a mapped marker in a pedigree of the other species in more than 40% of the cases, with about equal success in both directions. The maps of the two species are largely colinear, even if the species have diverged more than 70 MYA. Most cases of different locations were probably due to problems in identifying the orthologous members of gene families. These data provide a first ESTP-containing map of P. sylvestris, which can also be used for comparing this species to additional species mapped with the same markers.

Base Sequence↗

Development of nuclear gene-derived molecular markers linked to legume genetic maps.

The systematic identification of the orthologous features of related organisms greatly facilitates comparative genomics, including research on genome evolution and comparative genetic mapping. In this study, we selected 274 unique gene sequences for the development of PCR-based genetic markers across fifteen legume genomes, representing six crop or model legume species from the phaseoloid and inverted repeat loss clades (IRLC). DNA sequence analysis demonstrated that 129 of the amplified fragments represented single copy loci across most target diploid genomes. The majority of these markers are intron-spanning (70.5%) and linked to legume genetic maps (85.3%). The markers were grouped into four main categories: (1) intron-spanning relatively conserved, (2) intron-spanning diverged, (3) exon-derived conserved, and (4) exon-derived diverged. The extent of sequence divergence within each category indicates that the corresponding markers may have utility for assessing phylogenetic relationships at different, but overlapping, taxonomic levels. We tested marker performance on genomes that had not been previously sampled, representing 95 different species that span the diversity of the Fabaceae. Phylogenetic analyses support the orthology of amplified sequences, with the notable exception of an ambiguous affiliation of Lotus relative to the IRLC and phaseoloid clades.

Amino Acid Sequence↗

Genetic mapping: X chromosome.

Starting with the male chiasma distribution for chromosome 2, a significantly better fit is obtained to lod scores for the X chromosome if terminalization of distal chiasmata is assumed. The linkage data are not consistent with a uniform distribution of chiasmata, absence of terminalization, or restriction of terminalization to the distal band. As information about the genetic map of the X chromosome increases, the map will be freed from assumptions about chiasma distribution. At present, however, even fragmentary data on the male are useful to construct a genetic map that, by converting physical assignments to equivalent genetic recombinations, has no inconsistencies between genetic and physical map orders.

Chromosome Mapping↗

Genetic mapping of mutations in independently isolated nontoxinogenic mutants of Vibrio cholerae.

Conjugal mating experiments were performed between donor strains of Vibrio cholerae carrying the vibrio sex plasmid P and recipient strains lacking the P plasmid. Donor and recipient genotypes differed with respect to toxinogenicity (tox), nutritional requirements, and antibiotic susceptibilities. Recombinants carrying selected donor and recipient markers were produced at low frequencies in conjugal matings. Mapping of tox markers was accomplished by scoring for the frequency of coinheritance of the donor tox allele with selected and unselected donor markers. Four independently isolated tox markers were analyzed. Each of these four tox markers was shown to be linked to the his-1 site in linkage group I on the genetic map of V. cholerae. In matings between a recipient strain carrying the tox-1 marker and donor strains carrying either tox-2, tox-3, or tox-4, all selected his+ recombinants remained nontoxinogenic. Matings between multiply marked strains demonstrated that the position of tox-1 with respect to other genetic loci in linkage group I is as follows: met-2--trp-1--asp-1--nal-1--his-1--tox-1. These findings demonstrate that a chromosomal determinant linked to his-1 in linkage group I on the genetic map of V. cholerae is essential for toxinogenesis and suggest that tox-1,tox-2, tox-3, and tox-4 may be alleles of a single tox gene.

Cholera Toxin↗

Genetic architecture of qualitative and quantitative Melampsora larici-populina leaf rust resistance in hybrid poplar: genetic mapping and QTL detection.

In order to elucidate the genetic control of resistance to Melampsora larici-populina leaf rust in hybrid poplars, a Populus deltoides x P. trichocarpa F(1) progeny was analysed for qualitative and quantitative rust resistances. This progeny was evaluated for three components of quantitative resistance (latent period, uredinia number and uredinia size) to seven M. larici-populina strains in controlled conditions, and for one component of field susceptibility (rust colonization on the most infected leaf). One qualitative resistance locus inherited from P. deltoides, R(1), was localized on the genetic map. It segregates 1 : 1 in the F(1) progeny and is effective against four of the studied strains. QTL analysis was performed separately on R(1) and r(1) genotype subsets. An additional detection was conducted on the entire F(1) progeny for the three strains able to overcome R(1) and for MAX2. A total of nine QTLs were detected. Two had large, broad-spectrum effects. One (R(US)) is inherited from the P. trichocarpa parent; the other is inherited from P. deltoides and colocalized with R(1). Seven QTLs had only limited and specific effects. Significant interaction effects were detected mainly between the two major QTLs. Implications of these results for durable resistance breeding strategies, and possible benefits from the Populus genome sequence, are discussed.

Basidiomycota↗

A genetic map of chromosome 20q12-q13.1: multiple highly polymorphic microsatellite and RFLP markers linked to the maturity-onset diabetes of the young (MODY) locus.

Multiple highly polymorphic markers have been used to construct a genetic map of the q12-q13.1 region of chromosome 20 and to map the location of the maturity-onset diabetes of the young (MODY) locus. The genetic map encompasses 23 cM and includes 11 loci with PIC values > .50, seven of which have PICs > .70. New dinucleotide repeat polymorphisms associated with the D20S17, PPGB, and ADA loci have been identified and mapped. The dinucleotide repeat polymorphisms have increased the PIC of the ADA locus to .89 and, with an additional RFLP at the D20S17 locus, the PIC of the D20S17 locus to .88. The order of the D20S17 and ADA loci determined genetically (cen-ADA-D20S17-qter) was confirmed by multicolor fluorescence in situ hybridization. The previously unmapped PPGB marker is closely linked to D20S17, with a two-point lod score of 50.53 at theta = .005. These markers and dinucleotide repeat markers associated with the D20S43, D20S46, D20S55, D20S75, and PLC1 loci and RFLPs at the D20S16, D20S17, D20S22, and D20S33 have been used to map the MODY locus on chromosome 20 to a 13-cM (sex averaged) interval encompassing ADA, D20S17, PPGB, D20S16, and D20S75 on the long arm of chromosome 20 and to create a genetic framework for additional genetic and physical mapping studies of the region. With these multiple highly polymorphic loci, any MODY family of appropriate size can be tested for the chromosome 20 linkage.

Base Sequence↗