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Biomedical subjects

M Breen

Publications and source records attributed to M Breen.

At least 37 records · Page 2Linked to original sources
PubMed2000

Genomic structures and sequences of two closely linked genes (AMT, TCTA) on dog chromosome 20q15.1-->q15.2.

Analysis of genomic sequence from canine chromosome 20q15.1-->q15.2 revealed the presence of two closely linked genes. The two genes represent the corresponding canine orthologs of human aminomethyltransferase (AMT) and the human T-cell leukemia translocation associated (TCTA) gene. Aminomethyltransferase or glycine cleavage system T-protein is an important enzyme in glycine metabolism. The reported canine AMT gene spans 5 kb and consists of nine exons. It encodes a protein of 403 amino acids with 88% identity to human aminomethyltransferase. Human TCTA is located on 3p21 near the breakpoint of a t(1;3) translocation observed in some cancer cell lines. The 4-kb canine TCTA gene consists of three exons and probably represents a pseudogene. It is located adjacent to AMT and very close to DAG1 and BSN.

Aminomethyltransferase↗
PubMed1999

Reciprocal chromosome painting reveals detailed regions of conserved synteny between the karyotypes of the domestic dog (Canis familiaris) and human.

The domestic dog is increasingly being recognized as a useful model for human disease. The aim of this study was to conduct the first detailed whole-genome comparison of human and dog using bidirectional heterologous chromosome painting (reciprocal Zoo-FISH) analysis. We used whole-chromosome paint probes produced from degenerate oligonucleotide-primed PCR amplification of high-resolution bivariate flow-sorted human and dog chromosomes. No fewer than 68 evolutionarily conserved segments were identified between the dog and the human karyotypes. The use of elongated metaphase chromosomes for both species allowed the boundaries of each evolutionarily conserved segment to be determined to subband resolution. The distribution of conserved segments is discussed, as are the applications of these data in refining the current status of the dog genome map.

Animals↗
PubMed1999

Molecular characterization and chromosomal assignment of the canine protein C gene.

Protein C is a precursor to a serine protease present in the plasma that plays an important physiological role in the regulation of blood coagulation. Mutations in the human protein C gene have been linked to some cases of Morbus Perthes disease, a thrombophilic condition that results in aseptic necrosis of the femur head and neck. We have cloned the canine protein C gene to investigate whether Morbus Perthes disease in dogs is also caused by mutations within this gene. A genomic lambdaFIXII clone was isolated, and 11, 420 bp of DNA sequence were determined containing the complete protein C gene (Acc No. AJ001979). As in humans, the gene consists of nine exons with the translation start codon located in the second exon. The 1.7-kb mRNA contains a 1368-bp open reading frame coding for 456 amino acids. With the genomic protein C clone as a probe in a FISH experiment, the canine protein C gene was assigned to Chromosome (Chr) 19q21-q22. To search for possible mutations, we amplified genomic DNA from one healthy and 15 clinically and pathohistologically confirmed Morbus Perthes patients. Sequence analysis did not reveal any amino acid differences between the affected dogs and the normal control. Several nucleotide polymorphisms were detected, which however, did not result in an amino acid exchange. From these data we conclude that in contrast to human, canine Morbus Perthes disease is most likely not caused by mutations within the protein C gene.

Animals↗
PubMed1999

Chromosomal localization of acidic and basic keratin genes of the domestic dog.

Our laboratories are interested in characterizing genes involved in the myriad of heritable diseases affecting the domestic dog, Canis lupus familiaris, and in development of detailed genetic and physical maps of the canine genome. Included in these efforts is examination of conservation of the genetic organization, structure, and function of gene families involved in diseases of the canine skin, skeleton, and eye. To that end, study of the highly conserved keratin gene family was undertaken. Keratins belong to the superfamily of intermediate filaments and are the major structural proteins of the epidermis, hair, and nail. The keratins are highly conserved throughout vertebrate evolution both at the DNA and amino acid sequence levels. Mutations in genes encoding epithelial keratins are known to cause various diseases in humans, and similar histopathological presentations have been reported in the dog. The keratins are divided into two groups, type I (acidic) and type II (basic). In the human, the genes encoding the acidic and basic keratins are clustered on Chrs 17 and 12, respectively. The same genetic arrangement is seen in the mouse with the acidic and basic keratin gene clusters found on Chrs 11 and 15, respectively. Reported here are the chromosomal localization of acidic and basic canine keratin genes as well as supportive sequence data. Fluorescence in situ hybridization (FISH) experiments with clones isolated from a canine genomic library suggest that the acidic keratin gene cluster resides on CFA9 and the basic keratin gene cluster is located on CFA27.

Amino Acid Sequence↗
PubMed1999

Molecular analysis of a spontaneous dystrophin 'knockout' dog.

We have determined the molecular basis for skeletal myopathy and dilated cardiomyopathy in two male German short-haired pointer (GSHP) littermates. Analysis of skeletal muscle demonstrated a complete absence of dystrophin on Western blot analysis. PCR analysis of genomic DNA revealed a deletion encompassing the entire dystrophin gene. Molecular cytogenetic analysis of lymphocytes from the dam and both dystrophic pups confirmed a visible deletion in the p21 region of the affected canine X chromosome. Utrophin is up-regulated in the skeletal muscle, but does not appear to ameliorate the dystrophic canine phenotype. This new canine model should further our understanding of the physiological and biochemical processes in Duchenne muscular dystrophy.

Animals↗
PubMed1999

Localization and characterization of nucleotide sequences from the canine Y chromosome.

We previously reported the identification of a male-specific 658-bp DNA sequence in dogs. We used a specific primer pair designed for PCR amplification of this fragment with DNA samples from 238 dogs, 6 dingoes and 12 wolves. All 133 male samples amplified the 658-bp sequence, whereas all female samples did not. The sequence was not amplified from male DNA samples representing other wild canids (jackals, coyotes, foxes). A lambda phage was isolated from a canine male genomic library that contained an insert of approximately 15 kb of canine genomic DNA, including the male-specific 658-bp sequence. This lambda phage was used in fluorescence in-situ hybridization experiments. It hybridized to the canine Y chromosome together with a lambda clone containing a segment of the SRY gene and a cosmid clone containing a portion of the pseudoautosomal region. The male-specific 658-bp sequence was located at the end opposite to the pseudoautosomal region while the SRY gene sequence hybridized near the centromere. Additionally, two (CA)-repeat sequences were identified in the lambda clone that contained the 658-bp sequence. Specific primer pairs were designed to amplify each of the repeats. Primer pair MS34 amplified three different alleles from 13 unrelated canine male DNA samples with a PIC value of 0.40. Primer pair MS41 amplified five alleles with a PIC value of 0.71. These microsatellites are the first reported polymorphic sequences in the dog located in the non-recombining portion of the Y chromosome.

Animals↗
PubMed1999

The DAPI banded karyotype of the domestic dog (Canis familiaris) generated using chromosome-specific paint probes.

The domestic dog (Canis familiaris) is widely used as a model in the study of human disease. However, many of the 78 chromosomes comprising the canine karyotype are extremely difficult to identify reliably by classical cytogenetics. This has been a major hindrance to molecular cytogenetic studies of this species. The Animal Health Trust and the Sanger Centre have developed a set of canine whole chromosome-specific fluorescence in situ hybridisation (FISH) probes (chromosome paints). We have used these chromosome paints to identify unequivocally each chromosome in a metaphase spread. An increasing number of laboratories are making use of cooled CCD cameras and sophisticated software for FISH mapping. Consequently, there is a major trend towards the use of DAPI banding for concurrent chromosome identification during FISH analyses in a range of species. Here we present, for the first time, a complete DAPI banded karyotype of the dog in which each chromosome has been accurately placed, together with a 460-band DAPI ideogram. These data will facilitate the accurate assignment of FISH-mapped loci to all chromosomes comprising the karyotype and form the basis for an agreed standard of the dog karyotype.

Animals↗
PubMed1999

Genetic mapping of the copper toxicosis locus in Bedlington terriers to dog chromosome 10, in a region syntenic to human chromosome region 2p13-p16.

Abnormal hepatic copper accumulation is recognized as an inherited disorder in man, mouse, rat and dog. The major cause of hepatic copper accumulation in man is a dysfunctional ATP7B gene, causing Wilson disease (WD). Mutations in the ATP7B genes have also been demonstrated in mouse and rat. The ATP7B gene has been excluded in the much rarer human copper overload disease non-Indian childhood cirrhosis, indicating genetic heterogeneity. By investigating the common autosomal recessive copper toxicosis (CT) in Bedlington terriers, we have identified a new locus involved in progressive liver disease. We examined whether the WD gene ATP7B was also causative for CT by investigating the chromosomal co-localization of ATP7B and C04107, using fluorescence in situ hybridization (FISH). C04107 is an anonymous microsatellite marker closely linked to CT. However, BAC clones containing ATP7B and C04107 mapped to the canine chromosome regions CFA22q11 and CFA10q26, respectively, demonstrating that WD cannot be homologous to CT. The copper transport genes CTR1 and CTR2 were also excluded as candidate genes for CT since they both mapped to canine chromosome region CFA11q22. 2-22.5. A transcribed sequence identified from the C04107-containing BAC was found to be homologous to a gene expressed from human chromosome 2p13-p16, a region devoid of any positional candidate genes.

Adenosine Triphosphatases↗
PubMed1999

Zoo-FISH analysis of dog chromosome 5: identification of conserved synteny with human and cat chromosomes.

Conserved segments of synteny between the human genome and chromosome 5 (CFA 5) of the domestic dog (Canis familiaris) have been identified by reciprocal chromosome painting analysis. A CFA 5 paint probe was applied to human metaphase spreads, revealing distinct hybridisation sites on human (HSA) chromosomes 1, 11, 16, and 17. Paint probes for these human chromosomes were then hybridised to dog metaphase spreads, identifying the regions of CFA 5 with which homology is shared with the corresponding human chromosome. Application of the CFA 5 paint probe to metaphase spreads of the domestic cat (Felis catus, FCA) demonstrated hybridisation to cat chromosomes C1, D1, E1, and E2. Dog PCR primers for type 1 markers known to lie in the corresponding regions of HSA 11, 16, and 17 were used to isolate dog BAC clones representing four genes. Fluorescence in situ hybridisation analysis confirmed their localisation to CFA 5 and suggested that two of the conserved segments lie in opposing orientations on CFA 5, compared to the human chromosome concerned. A third segment appears to lie in the same orientation on both human and dog chromosomes. No suitable gene markers were available for analysis of the fourth segment. The significance of these findings is discussed with reference to current and future dog genome mapping efforts.

Animals↗
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↗
PubMed1997

Genetical and physical assignments of equine microsatellites--first integration of anchored markers in horse genome mapping.

Twenty equine microsatellites were isolated from a genomic phage library, and their genetical and physical localization was sought by linkage mapping and fluorescent in situ hybridization (FISH). Nineteen of the markers were found to be polymorphic with, in most cases, heterozygosities exceeding 50%. The markers were mapped in a Swedish reference family for gene mapping, comprising eight half-sib families from Standardbred and Icelandic horse sires. Segregation was analyzed against a set of 35 other markers typed in the pedigree. Thirteen of the microsatellites showed linkage to at least one other marker, with a total of 21 markers being involved in these linkages. In parallel, 18 of the microsatellites could be assigned to their chromosomal region by FISH. These assignments involved eight equine autosomes: ECA1, 2, 4, 6, 9, 10, 15, and 16. The genetical and physical mappings revealed by this study represent a significant extension of the current knowledge of the equine genome map.

Alleles↗