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Assignment of 112 microsatellite markers to 23 chromosome 11 subregions delineated by somatic hybrids: comparison with the genetic map.

Using a panel of 25 somatic cell hybrids, we have regionally localized 112 microsatellite markers generated by Généthon and assigned to chromosome 11. A genetic map of 74 of them was produced using linkage analysis of the eight largest CEPH (Centre d'Etude du Polymorphisme Humain) families. They could be ordered on chromosome 11 with an average distance of 2.1 cM. The tight correlation observed between the genetic order and the physical assignment of these microsatellites reinforces the genetic map data. These newly localized markers identified by the PCR method using a standardized protocol represent useful tools for mapping YAC clones and establishing YAC contigs and for studying genetic diseases or cancers associated with specific genes and/or germinal/somatic rearrangements of chromosome 11.

Animals↗

An integrated genetic map for linkage analysis.

Here I describe an Internet accessible database containing interpolated genetic map positions for 12917 marker loci. These are estimated via locally weighted linear regression (loess) from the Build 35.1 physical map position and the linkage map of Kong, X., and coworkers (2004) Am. J. Hum. Genet. 75:1143-1148. For the pseudoautosomal region, I have interpolated a male map based on the sperm typing data of Lien, S., and coworkers (2000) Am. J. Hum. Genet. 66:557-566.

Chromosome Mapping↗

Cosmid-derived markers anchoring the bovine genetic map to the physical map.

The mapping strategy for the bovine genome described in this paper uses large insert clones as a tool for physical mapping and as a source of highly polymorphic microsatellites for genetic typing, and was one objective of the BovMap Project funded by the European Union (UE). Eight-three cosmid and phage clones were characterized and used to physically anchor the linkage groups defining all the bovine autosomes and the X Chromosome (Chr). By combining physical and genetic mapping, clones described in this paper have led to the identification of the linkage groups corresponding to Chr 9, 12, 16, and 25. In addition, anchored loci from this study were used to orient the linkage groups corresponding to Chr 3, 7, 8, 9, 13, 16, 18, 19, and 28 as identified in previously published maps. Comparison of the estimated size of the physical and linkage maps suggests that the genetic length of the bovine genome may be around 4000 cM.

Animals↗

The human obese (OB) gene: RNA expression pattern and mapping on the physical, cytogenetic, and genetic maps of chromosome 7.

The recently identified mouse obese (ob) gene apparently encodes a secreted protein that may function in the signaling pathway of adipose tissue. Mutations in the mouse ob gene are associated with the early development of gross obesity. A detailed knowledge concerning the RNA expression pattern and precise genomic location of the human homolog, the OB gene, would facilitate examination of the role of this gene in the inheritance of human obesity. Northern blot analysis revealed that OB RNA is present at a high level in adipose tissue but at much lower levels in placenta and heart. OB RNA is undetectable in a wide range of other tissues. Comparative mapping of mouse and human DNA indicated that the ob gene is located within a region of mouse chromosome 6 that is homologous to a portion of human chromosome 7q. We mapped the human OB gene on a yeast artificial chromosome (YAC) contig from chromosome 7q31.3 that contains 43 clones and 19 sequence-tagged sites (STSs). Among the 19 STSs are eight corresponding to microsatellite-type genetic markers, including seven (CA)n repeat-type Genethon markers. Because of their close physical proximity to the human OB gene, these eight genetic markers represent valuable tools for analyzing families with evidence of hereditary obesity and for investigating the possible association between OB mutations and human obesity.

Adipose Tissue↗

A primary genetic map of chromosome 13q.

We have constructed a primary genetic map spanning most of human chromosome 13. A total of 14 polymorphic DNA sequences and one protein polymorphism provided, after construction of haplotypes, seven markers for the long arm of this chromosome. A panel of cell lines from 30 three-generation families with large sibship size served as the sample set. Pairwise cross analysis of the inheritance patterns of the marker loci established that six of the seven loci constituted a single linkage group; the seventh was localized by physical means. Significantly higher recombination rates were found in female than in male meioses in several intervals. The six closely linked loci were arranged, based on the two-point data, in three clusters, and a number of alternate gene orders were excluded by three-point linkage tests. The order and spacing of the individual loci were refined by linkage analyses that considered five loci jointly.

Chromosome Banding↗

Genetic mapping in Streptomyces clavuligerus by protoplast fusion.

The development of a protoplast manipulation protocol for the industrially important bacterium Streptomyces clavuligerus, which produces the beta-lactamase inhibitor clavulanic acid, made possible a preliminary genetic mapping study based on protoplast fusion crosses. A preliminary position for 11 markers on the S. clavuligerus genetic map is proposed. Fusion progeny were characterized by random spore analysis because the markers present in the strains were not amenable to the conventional four-on-four selection procedure. Whilst the resulting map is similar to that derived by conjugation for S. clavuligerus and S. coelicolor, further analysis of the markers is required to confirm these observations.

Alleles↗

Comparison of the genetic maps of variola and vaccinia viruses.

The complete genetic map of the variola major virus strain India-1967 is built basing on the sequence data. The suggested map is compared with the maps of the sequenced genomic regions of Copenhagen and Western Reserve strains of vaccinia virus and Harvey strain of variola major virus. The principle differences revealed in the genomic organization of these viruses are discussed.

DNA, Viral↗

A centromere-based genetic map of the short arm of human chromosome 6.

A genetic map of the short arm of chromosomes 6 (6p) has been constructed with 20 genetic markers that define 16 loci, including a locus at the centromere. The 40 CEPH families and, for 4 loci, 13 additional Utah families were genotyped. All 16 loci form a single linkage group extending from near the telomeric region to the centromere, covering 159 cM (Haldane) on the female map and 94 cM on the male map. Sex differences in recombination frequencies are noted for the 6p map, with an excess occurring in males at the distal end. The genetic order of loci is consistent with their physical localization on 6p. Proximal to the three most distal loci on the map, markers are especially dense, providing an extended region on 6p useful for localizing genes of interest.

Blotting, Southern↗

Chiasma-based genetic maps of chromosome 21.

The available cytogenetic data on meiotic chiasmata have been used to construct sex-specific genetic maps, showing the genetic distances and recombination fractions along the length of 21q. The male maps are based on direct observations of spermatocytes, while the female maps are derivations related to the increased chromosome length in oocytes. The male chiasma data have also been used as a frame of reference for ordering and positioning loci on the physical map with D21S110 as a fixed point.

Chromosome Mapping↗

Genetic mapping of Dn7, a rye gene conferring resistance to the Russian wheat aphid in wheat.

The Russian wheat aphid is a significant pest problem in wheat and barley in North America. Genetic resistance in wheat is the most effective and economical means to control the damage caused by the aphid. Dn7 is a rye gene located on chromosome 1RS that confers resistance to the Russian wheat aphid. The gene was previously transferred from rye into a wheat background via a 1RS/1BL translocation. This study was conducted to genetically map Dn7 and to characterize the type of resistance the gene confers. The resistant line '94M370' was crossed with a susceptible wheat cultivar that also contains a pair of 1RS/1BL translocation chromosomes. The F(2) progeny from this cross segregated for resistance in a ratio of 3 resistant: 1 susceptible, indicating a single dominant gene. One-hundred and eleven RFLP markers previously mapped on wheat chromosomes 1A, 1B and 1D, barley chromosome 1H and rye chromosome 1R, were used to screen the parents for polymorphism. A genetic map containing six markers linked to Dn7, encompassing 28.2 cM, was constructed. The markers flanking Dn7 were Xbcd1434 and XksuD14, which mapped 1.4 cM and 7.4 cM from Dn7, respectively. Dn7 confers antixenosis, and provides a higher level of resistance than that provided by Dn4. The applications of Dn7 and the linked markers in wheat breeding are discussed.

Animals↗

Integration of chicken cytogenetic and genetic maps: 18 new polymorphic markers isolated from BAC and PAC clones.

As an approach to integrate the chicken genetic and cytogenetic maps, bacterial artificial chromosome (BAC) and P1-derived artificial chromosome (PAC) clones were localized by fluorescence in situ hybridization (FISH) on chromosomes and by genetic mapping on the East Lansing and Compton reference families. Some of the clones used in this study were previously selected for the presence of potentially polymorphic (CA)n repeats and a microsatellite marker was developed when possible for genetic mapping. For other clones, a single strand conformational polymorphism (SSCP) was developed and used for this purpose. Between the two approaches, 18 markers linking the cytogenetic and genetic maps, seven on macrochromosomes and 11 on microchromosomes, were generated. Our results enabled the assignment and orientation of a linkage group to chromosome 3, together with the assignment of linkage groups to eight different microchromosomes, a fraction of the genome lacking mapping data and for which the degree of coverage by the genetic map was not well estimated previously.

Animals↗

Molecular basis of mutations at the waxy locus of maize: correlation with the fine structure genetic map.

More than 40 mutant alleles of the waxy (Wx) locus of maize are available for molecular analysis. Previous studies have examined the nature of phenotypically unstable Wx mutant alleles caused by insertion of the maize transposable activator (Ac) and dissociation (Ds) elements. In this study we have used Southern blot analysis to characterize the locus in 22 strains harboring wx alleles with stable mutant phenotypes. Of these mutations, 17 are of spontaneous origin, 4 were induced by gamma rays, and 1 was induced by ethyl methanesulfonate. Of these 22 alleles, we find that 13 have either insertions or deletions within the Wx transcription unit. The insertions range in size from 150 base pairs to 6.1 kilobases. For 4 of the 6 deletions identified, the two breakpoints are within the Wx gene. For 9 other alleles we can detect no obvious lesions within or around the transcription unit. Evidence is presented that the insertions and deletions result in the mutant phenotype and are not polymorphisms. This conclusion is based on two findings: (i) a survey of inbred lines revealed only a single instance of polymorphism within the transcription unit, whereas all of the lesions described alter the transcription unit; and (ii) there is an excellent correlation between the position of these lesions on the physical map and their relative position on a fine structure genetic map of the locus.

Alleles↗

Single pass sequencing and physical and genetic mapping of human brain cDNAs.

We have performed single pass sequencing of 1,024 human brain cDNAs, over 900 of which seem to represent new human genes. Library prescreening with total brain cDNA significantly reduced repeated sequencing of highly represented cDNAs. A subset of sequenced cDNAs were physically mapped to their chromosomal locations using gene-specific STS primers derived from 3' untranslated regions. We have also determined that human brain cDNAs represent a rich source of gene-associated polymorphic markers. Microsatellite-containing cDNAs can be physically mapped and converted to highly informative genetic markers, thus facilitating integration of the human physical, expression and genetic maps.

Base Sequence↗

High-throughput microsatellite analysis using fluorescent dUTPs for high-resolution genetic mapping of the mouse genome.

The use of fluorescent end-labeled primers has proved successful for rapid, semiautomated genotyping of microsatellite loci. However, custom synthesis is expensive and costs can be prohibitive when a wide range of markers is to be analyzed for only a few genotypings. This particularly applies to high-resolution genetic mapping in the mouse either in the construction of global maps or in the production of local high-resolution genetic maps for positional cloning. We demonstrate here the use of fluorescent dUTPs for cost-effective, high-throughput microsatellite genotyping in the mouse. This alternative to the use of fluorescent end-labeled primers for semiautomated genotyping is potentially applicable to the construction of linkage maps in other species.

Animals↗

Physical and genetic map of the Pasteurella multocida A:1 chromosome.

A physical and genetic map of the Pasteurella multocida A:1 genome was generated by using the restriction enzymes ApaI, CeuI, and NotI. The positions of 23 restriction sites and 32 genes, including 5 rrn operons, were localized on the 2.35-Mbp single circular chromosome. This report presents the first genetic and physical map for this genus.

Chromosome Mapping↗

A genetic map of Dictyostelium discoideum based on mitotic recombination.

A genetic map of the cellular slime mold Dictyostelium discoideum is presented in which 42 loci are ordered on five of the seven linkage groups. Although most of the loci were ordered using standing mitotic crossing-over techniques in which recessive selective markers were employed, use was also made of unselected recombined haploid strains. Consistent with cytological studies in which the chromosomes appear to be acrocentric, only a single arm has been found for each of the five linkage groups studied. The mating-type locus, matA, has been located in the tsgE-sprA interval on linkage group I on the basis of studies on diploids formed between strains of opposite mating type that have escaped from vegetative incompatibility.

Chromosome Mapping↗

Characterization and genetic mapping of a short, highly repeated, interspersed DNA sequence from rice (Oryza sativa L.).

A short, highly repeated, interspersed DNA sequence from rice was characterized using a combination of techniques and genetically mapped to rice chromosomes by restriction fragment length polymorphism (RFLP) analysis. A consensus sequence (GGC)n, where n varies from 13-16, for the repeated sequence family was deduced from sequence analysis. Southern blot analysis, restriction mapping of repeat element-containing genomic clones, and DNA sequence analysis indicated that the repeated sequence is interspersed in the rice genome, and is heterogeneous and divergent. About 200,000 copies are present in the rice genome. Single copy sequences flanking the repeat element were used as RFLP markers to map individual repeat elements. Eleven such repeat elements were mapped to seven different chromosomes. The strategy for characterization of highly dispersed repeated DNA and its uses in genetic mapping, DNA fingerprinting, and evolutionary studies are discussed.

Amino Acid Sequence↗