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Genetic mapping in the red mason bee implicates ANTSR as an ancient sex-determining locus in bees and ants.

Haplodiploid inheritance, in which females are diploid and males are haploid, is found in all species of Hymenoptera. Sex in haplodiploids is commonly determined by the alleles present at a complementary sex determination (CSD) locus, with heterozygosity triggering the female developmental pathway. The identity of this locus differs among taxa and is only known in a few species. Here, we map a single CSD locus to a 2 kbp region in the genome of the red mason bee Osmia bicornis. It overlaps the long noncoding RNA ANTSR, which has been identified as the sex-determining gene in the invasive ant Linepithema humile. This locus is homozygous in diploid males and exhibits extremely high levels of haplotype diversity, consistent with the action of frequency-dependent selection. The elevated levels of heterozygosity in the CSD locus enable us to fine-map potentially functional genetic variation within it. We also identify elevated levels of genetic diversity in the ortholog of the CSD locus in five other bee and ant genera, suggesting that it may govern sex determination widely in Hymenoptera. Our data are consistent with the hypothesis that ANTSR evolved a role in sex determination over 150 million years ago and is the ancestral sex-determination locus of bees and ants.

Animals↗

Physical and genetic mapping of the dipeptidase gene DPEP1 to 16q24.3.

We report the subregional physical and genetic mapping on chromosome 16q of a cDNA clone selected as a potential tumor/growth suppressor sequence. By DNA sequencing and RNA expression pattern, this clone was identified as part of the renal dipeptidase gene (DPEP1). Using somatic cell hybrids carrying either different human chromosomes or chromosome 16 segments, we confirm and refine the physical mapping of DPEP1 to the chromosome 16 subregion q24.3. Two RFLPs, a biallelic polymorphism detected by TaqI and a VNTR detected by BamHI, EcoRI, and BglII, are described. Using the VNTR polymorphism, DPEP1 was shown to be linked to D16S7 with a maximum lod score of 5.8 at a recombination fraction of 0.03.

Animals↗

An intersubspecific genetic map of Lens.

A Lens map was developed based on the segregational analysis of five kinds of molecular and morphological genetic markers in 113 F(2) plants obtained from a single hybrid of Lens culinaris ssp. culinaris x L. c. ssp. orientalis. A total of 200 markers were used on the F(2) population, including 71 RAPDs, 39 ISSRs, 83 AFLPs, two SSRs and five morphological loci. The AFLP technique generated more polymorphic markers than any of the others, although AFLP markers also showed the highest proportion (29.1%) of distorted segregation. At a LOD score of 3.0, 161 markers were grouped into ten linkage groups covering 2,172.4 cM, with an average distance between markers of 15.87 cM. There were six large groups with 12 or more markers each, and four small groups with two or three markers each. Thirty-nine markers were unlinked. A tendency for markers to cluster in the central regions of large linkage groups was observed. Likewise, clusters of AFLP, ISSR or RAPD markers were also observed in some linkage groups, although RAPD markers were more evenly spaced along the linkage groups. In addition, two SSR, three RAPD and one ISSR markers segregated as codominant. ISSR markers are valuable tools for Lens genetic mapping and they have a high potential in the generation of saturated Lens maps.

Chromosome Mapping↗

Identification and genetic mapping of 151 dispersed members of 16 ribosomal protein multigene families in the mouse.

More than 150 individual members of 16 ribosomal protein multigene families were identified as DNA restriction fragments and genetically mapped. The ribosomal protein gene-related sequences are widely dispersed throughout the mouse genome. Map positions were determined by analysis of 144 progeny mice from both an interspecific (C57BL/6J x SPRET/Ei)F1 x SPRET/Ei and an intersubspecific (C57BL/6J x CAST/Ei)F1 x C57BL/6J backcross. In addition, 30 members of the multigene families encoding PGK1 ODC, and TPI, including five new loci for ODC and one new locus for TPI, were characterized and mapped. Interspecific backcross linkage data for 29 nonecotropic murine leukemia retroviruses endogenous to C57BL/6J mice are also reported. Transmission ratio distortions and recombination frequencies are compared between the two backcrosses.

Animals↗

The genetic map of finger millet, Eleusine coracana.

Restriction fragment length polymorphism (RFLP), amplified fragment length polymorphism (AFLP), expressed-sequenced tag (EST), and simple sequence repeat (SSR) markers were used to generate a genetic map of the tetraploid finger millet (Eleusine coracana subsp. coracana) genome (2n = 4x = 36). Because levels of variation in finger millet are low, the map was generated in an inter-subspecific F(2) population from a cross between E. coracana subsp. coracana cv. Okhale-1 and its wild progenitor E. coracana subsp. africana acc. MD-20. Duplicated loci were used to identify homoeologous groups. Assignment of linkage groups to the A and B genome was done by comparing the hybridization patterns of probes in Okhale-1, MD-20, and Eleusine indica acc. MD-36. E. indica is the A genome donor to E. coracana. The maps span 721 cM on the A genome and 787 cM on the B genome and cover all 18 finger millet chromosomes, at least partially. To facilitate the use of marker-assisted selection in finger millet, a first set of 82 SSR markers was developed. The SSRs were identified in small-insert genomic libraries generated using methylation-sensitive restriction enzymes. Thirty-one of the SSRs were mapped. Application of the maps and markers in hybridization-based breeding programs will expedite the improvement of finger millet.

Chromosome Mapping↗

Genetic mapping of the spinocerebellar ataxia 2 (SCA2) locus on chromosome 12q23-q24.1.

A refined genetic map of the spinocerebellar ataxia 2 locus was constructed through linkage and haplotype analysis of 11 large pedigrees from the Holguín SCA2 family collective. Three-point analysis makes a localization of the SCA2 mutation in the 6-cM interval D12S84-D12S79 likely. This is consistent with haplotype results indicating a crossover event between two branches of the SCA2 family Rs and placing the mutation on the telomeric side of D12S84. The microsatellite D12S105 within this interval shows a peak two-point lod score of Z = 16.14 at theta = 0.00 recombination and complete linkage disequilibrium among affected individuals. These data together with the observation of a common disease haplotype among all family ancestors support the notion of an SCA2 founder effect in Holguín province.

Adolescent↗

Construction of a high-resolution genetic map encompassing the hotfoot locus.

Hotfoot (ho) is a mutation affecting posture and movement. We report a new allele associated with the insertion of a transgene and its high-resolution mapping. Analysis of the transgene revealed that two complete and two truncated copies are inserted at the ho locus. The ho locus cosegregated with D6Mit299 in 702 meioses and is confined to a 1.1-cM region between the markers D6Mit122 and D6Mit174. If the order and distances between markers are consistent with previously published mapping data, the position of the ho locus must be revised and placed approximately 30 cM from the centromere. This high-resolution genetic map is the first step towards the positional cloning of the ho mutation.

Alleles↗

Localization of the Escherichia coli rnt gene encoding RNase T by using a combination of physical and genetic mapping.

The rnt gene encoding RNase T was cloned on a 13-kilobase BamHI fragment. Restriction analysis of the fragment and comparison of it with the Escherichia coli restriction map localized rnt to kilobase coordinates 1733 to 1746, corresponding to about 36 min on the genetic map. The map location was confirmed by cotransduction with the nearby zdg-229::Tn10 and ksgB1 markers.

Escherichia coli↗

A genetic mapping system in Caenorhabditis elegans based on polymorphic sequence-tagged sites.

We devised an efficient genetic mapping system in the nematode Caenorhabditis elegans which is based upon the differences in number and location of the transposable element Tc1 between the Bristol and Bergerac strains. Using the nearly completed physical map of the C. elegans genome, we selected 40 widely distributed sites which contain a Tc1 element in the Bergerac strain, but not in the Bristol strain. For each site a polymerase chain reaction assay was designed that can distinguish between the Bergerac Tc1-containing site and the Bristol "empty" site. By combining appropriate assays in a single reaction, one can score multiple sites within single worms. This permits a mutation to be rapidly mapped, first to a linkage group and then to a chromosomal subregion, through analysis of only a small number of progeny from a single interstrain cross.

Animals↗

Physical and genetic mapping of the muscle phosphofructokinase gene (PFKM): reassignment to human chromosome 12q.

Phosphofructokinase (PFK) is a key rate-limiting enzyme in glycolysis and represents a major control point in the metabolism of glucose. There are at least three known isoforms of PFK in humans, referred to as the muscle, platelet, and liver forms, each of which is differentially expressed in various tissues. The gene for muscle phosphofructokinase, PFKM, is mutated in Tarui disease and conceivably contributes to non-insulin-dependent diabetes mellitus (NIDDM). Based on physical and genetic mapping, we have found that the gene for PFKM does not map to chromosome 1 as previously described, but instead maps to chromosome 12. PCR analysis with a somatic cell hybrid mapping panel using primers derived from intron 6 and exon 18 of the PFKM gene showed consistent amplification of cell lines containing chromosome 12 (concordance, 100%). Fluorescence in situ hybridization analysis with CEPH YAC 762G4, isolated with exon 18 primers, indicated that this clone maps to 12q13, centromeric to the diacylglycerol kinase gene (DAGK) at 12q13. 3. A highly informative genetic marker isolated from YAC 762G4 was used to map PFKM genetically between the CHLC framework markers D12S1090 and D12S390. This placement for 762G4 was significantly proximal to the recently reported locus for a third gene for maturity onset diabetes of the young (MODY). The PFKM-associated microsatellite will be a valuable tool in the evaluation of PFKM in diabetic populations as well as in linkage analysis in families with Tarui disease.

Blotting, Southern↗

Genetic mapping of the Salmonella typhimurium pncB locus.

The nicotinic acid phosphoribosyltransferase locus pncB was located on the Salmonella typhimurium linkage map counterclockwise relative to pyrC. P22 and P1 transductional analyses revealed linkage of pncB with aroA and pyrD, indicating a pncB map position of approximately 20 map units. The results of these cotransduction experiments also indicated that the genetic map distance between gal and pyrD is greater than the published 2.2 map units.

Chromosome Mapping↗

Genetic mapping and QTL analysis of fiber-related traits in cotton ( Gossypium).

Cotton, the leading natural fiber crop, is largely produced by two primary cultivated allotetraploid species known as Upland or American cotton ( Gossypium hirsutum L.) and Pima or Egyptian cotton ( G. barbadense L.). The allotetraploid species diverged from each other and from their diploid progenitors (A or D genome) through selection and domestication after polyploidization. To analyze cotton AD genomes and dissect agronomic traits, we have developed a genetic map in an F2 population derived from interspecific hybrids between G. hirsutum L. cv. Acala-44 and G. barbadense L. cv. Pima S-7. A total of 392 genetic loci, including 333 amplified fragment length polymorphisms (AFLPs), 47 simple sequence repeats (SSRs), and 12 restriction fragment length polymorphisms (RFLPs), were mapped in 42 linkage groups, which span 3,287 cM and cover approximately 70% of the genome. Using chromosomal aneuploid interspecific hybrids and a set of 29 RFLP and SSR framework markers, we assigned 19 linkage groups involving 223 loci to 12 chromosomes. Comparing four pairs of homoeologous chromosomes, we found that with one exception linkage distances in the A-subgenome chromosomes were larger than those in their D-subgenome homoeologues, reflecting higher recombination frequencies and/or larger chromosomes in the A subgenome. Segregation distortion was observed in 30 out of 392 loci mapped in cotton. Moreover, approximately 29% of the RFLPs behaved as dominant loci, which may result from rapid genomic changes. The cotton genetic map was used for quantitative trait loci (QTL) analysis using composite interval mapping and permutation tests. We detected seven QTLs for six fiber-related traits; five of these were distributed among A-subgenome chromosomes, the genome donor of fiber traits. The detection of QTLs in both the A subgenome in this study and the D subgenome in a previous study suggests that fiber-related traits are controlled by the genes in homoeologous genomes, which are subjected to selection and domestication. Some chromosomes contain clusters of QTLs and presumably contribute to the large amount of phenotypic variation that is present for fiber-related traits.

Chromosome Mapping↗

Construction of a rat genetic map by using randomly amplified microsatellite polymorphism (RAMP) markers.

Many rat strains have been employed in the genetic study of quantitative traits such as blood pressure. In such genetic studies, it is essential to prepare rat genetic maps fine enough to identify the genes regulating quantitative traits. However, it is not an easy task to isolate a sufficient number of genetic markers polymorphic between a particular pair of rat strains. In this study, we applied the randomly amplified microsatellite polymorphism (RAMP) method, a simple method to identify co-dominant markers (Wu et al. Nucleic Acids Res 22, 3257, 1994), to isolate markers polymorphic between the stroke-prone spontaneously hypertensive rat and the Wistar-Kyoto rat, a genetically hypertensive strain and its normotensive control strain, which share a common genetic background. We successfully identified 111 RAMP markers distributed throughout the rat genome after screening 3046 sets of primers. We also showed that we could isolate ordinary simple-sequence-length-polymorphism markers by cloning RAMP markers. The RAMP method is a simple and efficient way to identify co-dominant genetic markers on mammalian genomes.

Animals↗

Orientation of nonsense codons on the genetic map of the lac operon.

Intracodon recombination is used to orient the nonsense codons UGA, UAG, and UAA on the genetic map of the (lactose) lac operon of Escherichia coli. The 5'-end of these triplets is toward the operator end of the operon. A hypothesis is presented to explain the fact that the frequency of recombination between adjacent nucleotides is many times lower than expected.

Chromosome Mapping↗

Location of the maltose A and B loci on the genetic map of Escherichia coli.

Schwartz, Maxime (Institut Pasteur, Paris, France). Location of the maltose A and B loci on the genetic map of Escherichia coli. J. Bacteriol. 92:1083-1089. 1966.-All of the mutations impairing maltose metabolism that have been found in Escherichia coli map in one of the two loci, malA and malB. The position of malA in relation to the streptomycin, diaminopimelic acid + homoserine, and glycerol D loci were established both by sexual crosses and by P1 transduction. A new biotin marker was also shown to be located in this region. The position of malB was studied in relation to the loci for arginine F, methionine A, ultraviolet radiation A, and the origin of transfer of Hfr P10.

Amino Acids↗