Physical and linkage mapping of the bovine bone morphogenetic protein 1 on the evolutionary break region of BTA 8

Bone morphogenetic protein 1 (BMP1) has been proposed as a regulatory molecule involved in the binding or activation of other BMP molecules. It has been described as being identical to the enzyme C-proteinase that processes procollagens to fibrillar collagens. A fragment containing an exon of the bovine BMP1 gene was amplified from an adapter-ligated genomic DNA library. The isolated bovine BMP1 fragment was assigned by fluorescence in situ hybridization (FISH) to bovine (BTA) chromosome 8q21, a region containing an evolutionary breakpoint between homology to human (HSA) chromosomes 8 and 9. The assignment to BTA 8 was confirmed by using a hybrid somatic cell panel. The 3' intron region of the amplified genomic BMP1 fragment showed a SSCP polymorphism, and linkage analysis in the International Bovine Reference Panel (IBRP) of families confirmed the boundary position of this gene. The BMP1 gene presents total linkage (theta = 0.00, Z = 3.61) with the lipoprotein lipase gene on BTA 8 and HSA 8 and a larger recombination fraction (theta = 0.11, Z = 5.03) with the marker GGTB2 on BTA 8 and HSA 9. Physical and genetic mapping of the bovine BMP1 gene contribute to narrow the boundary between the HSA 8 and HSA 9 homology segments on BTA 8 and to the comparative mapping between BTA 8, murine chromosome MMU 14, and HSA 8.

Sequence analysis of MHC class I alpha 2 domain exon variants in one diploid and two haploid Atlantic salmon pedigrees

Genetic diversity in the second domain exon of Atlantic salmon (Salmo salar) major histocompatibility complex (Mhc) class I was investigated in two dams and nine of their haploid offspring by means of polymerase chain reaction (PCR) and DNA sequence analysis. A similar study was also performed on nine diploid offspring from one of these dams. The complex segregation patterns and sequence similarities between variants make definitive allele, haplotype and locus assignments difficult. There are, however, indications of six Mhc-Sasa class I loci and a fairly well-defined haplotype of four variants. One non-polymorphic variant present in most specimens could be a salmon analogue to the human non-classical loci.

Segregation studies and linkage analysis of Atlantic salmon microsatellites using haploid genetics

A genetic marker map of Atlantic salmon would facilitate the identification of loci influencing economically important traits. In the present paper we describe five new Atlantic salmon microsatellites. Segregation studies and linkage analysis of these and previously published microsatellites were carried out in pedigrees consisting of diploid dams and haploid gynogenetic offspring. We confirm earlier reports that salmon microsatellites tend to have a higher number of repeat units than those of mammals. Linkage analysis revealed that three microsatellites belong to a linkage group spanning approximately 50 cM of the genome, whereas the remaining 10 markers seem to be unlinked.

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.

FISH mapping of three bovine cosmids to cattle, goat, sheep and buffalo X chromosomes

Contrary to extensive banding similarities of the autosomes, there are variations in the morphology as well as banding patterns of the X chromosomes of various species of bovidae family. We used three bovine X chromosome specific cosmid clones for fluorescence in situ hybridization mapping on cattle, goat, sheep, and river buffalo chromosomes to identify homologous regions in the genomes of the four species. The three cosmids (cIOBT 314, 945, and 1489) mapped to well spaced locations on buffalo X, and both arms of cattle X chromosome. However, of the three probes, cosmids cIOBT 314 and 1489 showed no hybridization signal on any of the goat-sheep chromosomes. Incidentally, the two cosmids show correspondence to those regions of the buffalo X chromosome which are proposed to be lost during the structural reshuffle of the latter, leading to sheep/goat X chromosomes. The lack of hybridization signal of the two cosmids in sheep and goat, therefore, indicates that these DNA sequences are most likely absent in the two genomes and probably correspond to the segments lost during evolution of their X chromosomes.

Comparative FISH mapping of bovine cosmids to reindeer chromosomes demonstrates conservation of the X-chromosome

Three X chromosome-specific bovine cosmids were used for fluorescence in situ hybridization mapping on reindeer (Rangifer tarandus) chromosomes, to test whether such large genomic clones could be used for comparative mapping across distantly related species. All three cosmids showed distinct unique hybridization sites on the reindeer X. Comparative map locations of these cosmids, together with the relative C-banding and genome size data on the X chromosomes of the two species, provide preliminary indications that the short and long arms of bovine X correspond, respectively, to the long and short arms of the reindeer X. The study also demonstrates that cosmid clones can be used successfully for comparative mapping across species that diverged 35 million years ago.

Combined Q-banding and fluorescence in situ hybridization for the identification of bovine chromosomes 1 to 7

Eleven probes were assigned to bovine chromosomes 1 to 7 by fluorescence in situ hybridization (FISH). The identification of chromosomes was based on QFQ-banding prior to in situ hybridization and comparison with the Reading Conference (1976) and ISCNDA (1989) standards. The probes used for FISH can now be utilized as identification and discrimination features for bovine chromosomes 1 to 7 and particularly for chromosomes 4 and 6, which are difficult to distinguish. Comparison of our mapping data with previous assignments and of the standard chromosome banding patterns prompt us to propose a change in the ISCNDA nomenclature: ISCNDA chromosome 4 should be named chromosome 6 and vice versa. Chromosome 4 is marked by the ribosomal RNA cluster RNR3, and chromosome 6 is characterized by the casein gene cluster and an anonymous satellite (D6Z1).

A study of variability in the MHC class II beta 1 and class I alpha 2 domain exons of Atlantic salmon, Salmo salar L

Variability in the most extracellular exons of Atlantic salmon MHC-Sasa class I and class II was studied by polymerase chain reaction (PCR) amplification followed by sequencing. The domains studied were class I alpha 2 and class II beta 1. The material used was genomic DNA of fish, mainly derived from the major Norwegian breeding pool, supplemented with some material from a minor breeder and a local river strain. The analysis revealed extensive variation, most individuals being heterozygous with at least two variants.

Distribution and hybridization patterns of the insertion element IS900 in clinical isolates of Mycobacterium paratuberculosis

Reference strains and 31 clinical isolates of M. paratuberculosis, mainly from goats, were analysed for restriction fragment length polymorphism (RFLP). Restriction digests of bacterial DNA were hybridized with a repetitive insertion sequence, IS900, to obtain banding patterns for comparison of strains. Twenty-five of the 31 field-strains hybridized with IS900, and five hybridization patterns were identified. It was not possible to identify specific patterns for goat strains of M. paratuberculosis. Four hybridization patterns were similar, whereas the fifth pattern of a sheep strain diverged considerably in position and number of bands. Six goat strains failed to hybridize with IS900, and the absence of IS900 was verified by the polymerase chain reaction and hybridization with an oligonucleotide probe. The six IS900-negative goat strains had diverging phenotypic properties, and the identification of these strains is discussed. The present study shows that M. paratuberculosis strains infecting goats are genetically similar to cattle strains and that IS900 is a specific genetic element for identification of M. paratuberculosis.

Isolation and sequence determination of porcine class II DRB alleles amplified by PCR

The first domain exon of a porcine DRB gene was amplified by the polymerase chain reaction (PCR), and the nucleotide sequence was determined. In a material consisting of 10 unrelated animals, five different alleles were identified, all probably belonging to a single locus designated DRB1. In addition, a non-expressed locus, designated DRB2, was coamplified with DRB1. This pseudogene, containing a single base deletion, also exhibited some variation, but at a very restricted level compared with DRB1. In pairwise comparisons of DRB1 alleles, the number of amino acid substitutions ranged between 6 and 21 out of 83 positions compared.

High lysozyme activity in a Norwegian bovine family co-segregates with a restriction fragment length polymorphism

Analysis of restriction fragment length polymorphism (RFLP) of the lysozyme gene cluster was performed in a Norwegian bovine family segregating a single dominant Mendelian factor for high lysozyme activity in serum. An RFLP site with allelic bands of 16kb and 5.9 kb turned out to be linked to the locus for the high lysozyme activity factor with a lod score of 6.8 at a recombination fraction of 3.4%. This implies that we have revealed a genetic marker for the high lysozyme activity trait.

A fast and highly sensitive method for detecting freemartinism in bovine twins using immunomagnetic beads and Y-specific PCR primers

A method for detecting male cells in the blood of the female calf in bovine heterosexual twin pregnancies has been established. Nucleated cells were isolated from full blood by immunomagnetic separation, lysed by boiling and then subjected to polymerase chain reaction (PCR) amplification with Y chromosome specific primers. Diagnosis was achieved within one day. The method was successfully used on blood samples that had been stored at +4 degrees C for more than one month. Dilution of male blood in female blood showed that XY cells were detectable down to a concentration of 0.1%. This method should be amenable to automatization and can be adapted to any PCR-based genetic test.

Characterization of a set of variable number of tandem repeat markers conserved in bovidae

Screening purpose-built libraries with minisatellite probes, we have isolated 36 bovine variable number of tandem repeat markers (VNTRs) characterized by a mean heterozygosity of 59.3 within the American Holstein breed. Matching probabilities and exclusion powers were estimated by Monte-Carlo simulation, showing that the top 5 to 10 markers could be used as a very efficient DNA-based system for individual identification and paternity diagnosis. The isolated VNTR systems should contribute significantly to the establishment of a bovine primary DNA marker map. Linkage analysis, use of somatic cell hybrids, and in situ hybridization demonstrate that these bovine VNTRs are scattered throughout the bovine genome, without evidence for proterminal confinement as in the human, and that at least some of them are organized as clusters. Moreover, Southern blot analysis and in situ hybridization demonstrate conservation of sequence and map location of minisatellites within Bovidae.

The major histocompatibility complex of reindeer

The major histocompatibility complex (MHC) is a system of closely linked genes showing an extremely high degree of polymorphism. These genes are major elements in the government of specific immune reactions. Consequently they may represent a genetic marker system well suited to investigate variability in selective pressure from disease agents on different populations. On this background we have started investigation of the MHC complex in reindeer (Rangifer tarandus L). The MHC complex consist of polymorphic regions as well as regions conserved during evolution which should allow the use of cross-species reagents. We have shown that human MHC gene probes hybridize with genomic DNA from reindeer, and thus can be used as a tool in reindeer MHC research. By RFLP (restriction fragment length polymorphism) analysis using these probes we have also been able to show polymorphism in MHC related genes from reindeer.