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A T Bowling

Publications and source records attributed to A T Bowling.

At least 19 recordsLinked to original sources
PubMed2003

The second generation of the International Equine Gene Mapping Workshop half-sibling linkage map.

A low-density, male-based linkage map was constructed as one of the objectives of the International Equine Gene Mapping Workshop. Here we report the second generation map based on testing 503 half-sibling offspring from 13 sire families for 344 informative markers using the CRIMAP program. The multipoint linkage analysis localized 310 markers (90%) with 257 markers being linearly ordered. The map included 34 linkage groups representing all 31 autosomes and spanning 2262 cM with an average interval between loci of 10.1 cM. This map is a milestone in that it is the first map with linkage groups assigned to each of the 31 automosomes and a single linkage group to all but three chromosomes.

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PubMed2003

Genetic variation in Przewalski's horses, with special focus on the last wild caught mare, 231 Orlitza III.

In our continuing efforts to document genetic diversity in Przewalski's horses and relatedness with domestic horses, we report genetic variation at 22 loci of blood group and protein polymorphisms and 29 loci of DNA (microsatellite) polymorphisms. The loci have been assigned by linkage or synteny mapping to 20 autosomes and the X chromosome of the domestic horse (plus four loci unassigned to a chromosome). With cumulative data from tests of 568 Przewalski's horses using blood, hair or tooth samples, no species-defining markers were identified, however a few markers were present in the wild species but not in domestic horses. Inheritance patterns and linkage relationships reported in domestic horses appeared to be conserved in Przewalski's horses. A derived type for the last wild caught mare 231 Orlitza III provided evidence for markers apparently not found in (or not currently available by descent from) the other species founders that were captured at the end of the nineteenth century. This information has been critical to the development of parentage analyses in the studbook population of Przewalski's horses at Askania Nova, at one time the largest herd of captive animals and the source of stock for reintroduction efforts. Some horses in the study showed genetic incompatibilities with their sire or dam, contradicting published studbook information. In many cases alternative parentage could be assigned from living animals. To assist in identification of correct parentage, DNA marker types for deceased horses were established from archived materials (teeth) or derived from offspring. Genetic markers were present in pedigreed animals whose origin could not be accounted for from founders. Genetic distance analysis of erythrocyte protein, electrophoretic and microsatellite markers in Przewlaski's horses and ten breeds of domestic horse place the Przewalski's horse as an outgroup to domestic horses, introgression events from domestic horses not withstanding.

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PubMed2001

The cream dilution gene, responsible for the palomino and buckskin coat colours, maps to horse chromosome 21.

The colour locus historically referred to as C in the horse is linked to microsatellites markers on horse chromosome 21. Preliminary results demonstrated linkage of Ccr, thought to be the cream dilution variant of the C locus, to HTG10. An analysis of horse chromosome 21 using additional families confirmed and established a group of markers linked to Ccr. This work also improved the resolution of previously reported linkage maps for this chromosome. Linkage analysis unambiguously produced the map order: SGCV16-(19.1 cM)-HTG10-(3.8 cM)-LEX60/COR73-(1.3 cM)-COR68-(4.5 cM)- Ccr-(11.9 cM)-LEX31. Comparative and synteny data suggested that the horse C locus is not tyrosinase (TYR).

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PubMed2000

Synteny and regional marker order assignment of 26 type I and microsatellite markers to the horse X- and Y-chromosomes.

The hypothesis that the conservation of sex-chromosome-linked genes among placental mammals could be extended to the horse genome was tested using the UCDavis horse-mouse somatic cell hybrid (SCH) panel. By exploiting the fluorescence in-situ hybridization (FISH) technique to localize an anchor locus, X-inactivation-specific transcript (XIST) on the horse X chromosome, together with the fragmentation and translocation of the X- and Y-chromosome fragments in a somatic cell hybrid panel, we regionally assigned 13 type I and 13 type II (microsatellite) markers to the horse X- and Y-chromosomes. The synteny groups that correspond to horse X- and Y-chromosomes were identified by synteny mapping of sex-specific loci zinc finger protein X-linked (ZFX), zinc finger protein Y-linked (ZFY) and sex-determining region Y (SRY) on the SCH panel. A non-pseudoautosomal gene in the human steroid sulfatase (STS) was identified in both X- and Y-chromosome-containing clones. The regional order of the X-linked type I markers examined in this study, from Xp- to Xq-distal, was [STS-X, the voltage-gated chloride channel 4 (CLCN4)], [ZFX, delta-aminolevulinate synthase 2 (ALAS2)], XIST, coagulation factor IX (F9) and [biglycan (BGN), equine F18, glucose-6-phosphate dehydrogenase (G6PD)] (precise marker order could not be determined for genes within the same brackets). The order of the Y-linked type I markers was STS-Y, SRY and ZFY These orders are the same arrangements as reported for the human X- and Y-chromosomes, supporting the conservation of genomic organization between the human and the horse sex chromosomes. Regional ordering of X-linked type I and microsatellite markers provides the first integration of type I and type II markers in the horse X chromosome.

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PubMed2000

A pedigree-based study of mitochondrial D-loop DNA sequence variation among Arabian horses.

Through DNA sequence comparisons of a mitochondrial D-loop hypervariable region, we investigated matrilineal diversity for Arabian horses in the United States. Sixty-two horses were tested. From published pedigrees they traced in the maternal line to 34 mares acquired primarily in the mid to late 19th century from nomadic Bedouin tribes. Compared with the reference sequence (GenBank X79547), these samples showed 27 haplotypes with altogether 31 base substitution sites within 397 bp of sequence. Based on examination of pedigrees from a random sampling of 200 horses in current studbooks of the Arabian Horse Registry of America, we estimated that this study defined the expected mtDNA haplotypes for at least 89% of Arabian horses registered in the US. The reliability of the studbook recorded maternal lineages of Arabian pedigrees was demonstrated by haplotype concordance among multiple samplings in 14 lines. Single base differences observed within two maternal lines were interpreted as representing alternative fixations of past heteroplasmy. The study also demonstrated the utility of mtDNA sequence studies to resolve historical maternity questions without access to biological material from the horses whose relationship was in question, provided that representatives of the relevant female lines were available for comparison. The data call into question the traditional assumption that Arabian horses of the same strain necessarily share a common maternal ancestry.

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PubMed1999

Comparative mapping of 18 equine type I genes assigned by somatic cell hybrid analysis.

Polymerase chain reaction primers designed from horse cDNA sequences and from consensus sequences highly conserved in mammalian species were used to amplify markers for synteny mapping 18 equine type I genes. These markers were used to screen a horse-mouse somatic cell hybrid panel (UCDavis SCH). Fourteen primer sets amplified horse-specific fragments, while restriction enzyme digests of PCR products were used to distinguish the fragments amplified from horse and mouse with four primer sets. Synteny assignments were made based on correlation values between each marker tested and other markers in the UCDavis SCH panel database. The 18 horse genes were assigned to previously established synteny groups. Synteny mapping of two genes previously mapped in the horse by FISH was used to anchor two UCD synteny groups to horse chromosomes. Previous chromosome assignments of three equine loci by FISH were confirmed. Comparative mapping analysis based on published human-horse Zoo-FISH data and the synteny mapping of 14 horse genes confirmed the physical assignment of 12 synteny groups to the respective horse chromosomes and was used to infer the physical location of one synteny group.

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PubMed1999

Equine synteny mapping of comparative anchor tagged sequences (CATS) from human Chromosome 5.

Comparative anchor tagged sequences (CATS) from human Chromosome 5 (HSA5) were used as PCR primers to produce molecular markers for synteny mapping in the horse. Primer sets for 21 genes yielded eight horse-specific markers, which were mapped with the UC Davis horse-mouse somatic cell hybrid panel into two synteny groups: UCD14 and UCD21. These data, in conjunction with earlier human chromosome painting studies of the horse karyotype and synteny mapping of horse microsatellite markers physically mapped by FISH, confirm the assignment of UCD21 to ECA21 and suggest that UCD14 is located on ECA14. In addition, our results can be used to substantiate previously published data which indicate that ECA21 contains material orthologous to HSA5p and HSA5q, and to propose an approximate region for an evolutionary chromosomal rearrangement event.

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PubMed1999

A synteny map of the horse genome comprised of 240 microsatellite and RAPD markers.

To generate a domestic horse genome map we integrated synteny information for markers screened on a somatic cell hybrid (SCH) panel with published information for markers physically assigned to chromosomes. The mouse-horse SCH panel was established by fusing pSV2neo transformed primary horse fibroblasts to either RAG or LMTk mouse cells, followed by G418 antibiotic selection. For each of the 108 cell lines of the panel, we defined the presence or absence of 240 genetic markers by PCR, including 58 random amplified polymorphic DNA (RAPD) markers and 182 microsatellites. Thirty-three syntenic groups were defined, comprised of two to 26 markers with correlation coefficient (r) values ranging from 0.70 to 1.0. Based on significant correlation values with physically mapped microsatellite (type II) or gene (type I) markers, 22 syntenic groups were assigned to horse chromosomes (1, 2, 3, 4, 6, 9, 10, 11, 12, 13, 15, 18, 19, 20, 21, 22, 23, 24, 26, 30, X and Y). The other 11 syntenic groups were provisionally assigned to the remaining chromosomes based on information provided by heterologous species painting probes and work in progress with type I markers.

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PubMed1999

Report of the International Equine Gene Mapping Workshop: male linkage map.

The goal of the First International Equine Gene Mapping Workshop, held in 1995, was the construction of a low density, male linkage map for the horse. For this purpose, the International Horse Reference Family Panel (IHRFP) was established, consisting of 12 paternal half-sib families with 448 half-sib offspring provided by 10 laboratories. Blood samples were collected and DNA extracted in each laboratory and sent to the Lexington laboratory (KY, USA) for dispatch in aliquots to 14 typing laboratories. In total, 161 markers (144 microsatellites, seven blood groups and 10 proteins) were tested for all families for which the sire was heterozygous. Genealogies and typing data were sent for analysis to the INRA laboratory (Jouy-en-Josas, France) according to a specific format and entered into a database with input verification and output processes. Linkage analysis was performed with the CRIMAP program. Significant linkage was detected for 124 loci, of which 95 were unambiguously ordered using a multipoint analysis with an average spacing of 14.2 CM. These loci were distributed among 29 linkage groups. A more comprehensive analysis including synteny group data and FISH data suggested that 26 autosomes out of 31 are covered. The complete map spans 936 CM.

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PubMed1999

A comparative gene map of the horse (Equus caballus).

A comparative gene map of the horse genome composed of 127 loci was assembled based on the new assignment of 68 equine type I loci and on data published previously. PCR primers based on consensus gene sequences conserved across mammalian species were used to amplify markers for assigning 68 equine type I loci to 27 horse synteny groups established previously with a horse-mouse somatic cell hybrid panel (SCHP, UC Davis). This increased the number of coding genes mapped to the horse genome by over 2-fold and allowed refinements of the comparative mapping data available for this species. In conjunction with 57 previous assignments of type I loci to the horse genome map, these data have allowed us to confirm the assignment of 24 equine synteny groups to their respective chromosomes, to provisionally assign nine synteny groups to chromosomes, and to further refine the genetic composition established with Zoo-FISH of two horse chromosomes. The equine type I markers developed in this study provide an important resource for the future development of the horse linkage and physical genome maps.

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