Molecular cloning of major histocompatibility complex class I cDNAs from Atlantic salmon (Salmo salar).
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Amino Acid Sequence↗
Biomedical subjects
I Olsaker
Publications and source records attributed to I Olsaker.
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.
Animals↗
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.
Abomasum↗
Homology between cryptic plasmid from Neisseria gonorrhoeae and genomic DNA from Neisseria meningitidis.
The human pathogenic Neisseria species N. gonorrhoeae and N. meningitidis are closely related. In contrast to N. meningitidis, however, almost all clinical isolates of N. gonorrhoeae harbour a phenotypically cryptic plasmid. In some gonococcal strains regions of the cryptic plasmid have been found in the gonococcal genome and it has been suggested that large segments of the cryptic plasmid can be integrated into the gonococcal chromosome of both plasmid-bearing and plasmid-free strains. Here we report homology between parts of the cryptic gonococcal plasmid and genomic DNA from four different N. meningitidis strains from systemic disease isolates in which no plasmids have been found with the applied methods. Serogroup B strains, causing many of the cases of meningococcal disease in Norway, hybridized strongly to the cryptic plasmid probe, in contrast to serogroup A and C strains. Clones hybridizing to the cryptic plasmid were isolated from a meningococcal genomic lambda EMBL3 DNA library and characterized by restriction mapping. When using one such clone as a probe the parts of the cryptic plasmid showing homology to the genomic meningococcal DNA were confined to two small separate regions of 420 and 88 bp.
DNA, Bacterial↗
High levels of linkage disequilibria between serologically defined class I bovine lymphocyte antigens (BoLA-A) and class II DQB restriction fragment length polymorphism (RFLP) in Norwegian cows.
Serum defined BoLA-A antigens, together with BoLA-DQB RFLP patterns, were determined in 87 almost unrelated Norwegian cattle. Statistical analysis revealed strong linkage disequilibria between these loci at the population level. A total of 13 haplotypes were found to be present at frequencies significantly greater than those predicted on the basis of their component gene frequencies. Among these, the subgroups 1A and 1B of the DQ1 haplotype were found to be closely associated with the class I antigens A11 and w16, respectively. The association between A11 and DQ1A is of particular interest, as two independent studies, one employing class I serology, and the other RFLP analysis of the class II locus DQ, have previously indicated that A11 and DQ1A confer relative susceptibility to mastitis.
Alleles↗
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.
Animals↗
Immunomagnetic isolation of cells for serological BoLA typing.
This paper describes a totally new immunomagnetic (IM) technique adapted to serological BoLA typing. The basic technique has recently been developed by Vartdal et al. (1986) for serological HLA typing. The main advantage is that bovine mononuclear cells (e.g. T-cells and possibly their subsets, B-cells and monocytes) can be quickly and specifically isolated with high yield and viability from whole blood in a one-step procedure. This is achieved by magnetic separation of rosettes formed between the cells and superparamagnetic monosized polystyrene microspheres (Dynabeads TM) coated with cross-species reactive monoclonal antibodies (MAbs) specific for various human T-cell antigens or for HLA class II monomorphic epitopes. The cells are isolated within 5 min after a 5-min incubation at 4 degrees C. Magnetic separation of rosettes with a strong cobalt-samarium magnet eliminates all the laborious centrifugation steps necessary with conventional procedures. The isolated cells, still attached to the particles, are available for microcytotoxic assay. This is carried out within 55 min, including a two-step application of alloantiserum and complement and addition of acridine orange/ethidium bromide for the staining of viable (green) and dead (red) cells. The high viability of isolated cells gives a very low background kill compared with the conventional cytotoxic assay. The IM typing technique is also superior in sensitivity to the conventional technique as standardized for the international BoLA comparison test. The IM technique is likely to have its greatest impact on class II typing; class II positive cells being separated very efficiently. Polymorphic HLA class II MAbs detected likely polymorphic BoLA class II epitopes.
Animals↗
Genetic diversity and population structure of 20 North European cattle breeds.
Blood samples were collected from 743 animals from 15 indigenous, 2 old imported, and 3 commercial North European cattle breeds. The samples were analyzed for 11 erythrocyte antigen systems, 8 proteins, and 10 microsatellites, and used to assess inter- and intrabreed genetic variation and genetic population structures. The microsatellites BoLA-DRBP1 and CSSM66 were nonneutral markers according to the Ewens-Watterson test, suggesting some kind of selection imposed on these loci. North European cattle breeds displayed generally similar levels of multilocus heterozygosity and allelic diversity. However, allelic diversity has been reduced in several breeds, which was explained by limited effective population sizes over the course of man-directed breed development and demographic bottlenecks of indigenous breeds. A tree showing genetic relationships between breeds was constructed from a matrix of random drift-based genetic distance estimates. The breeds were classified on the basis of the tree topology into four major breed groups, defined as Northern indigenous breeds, Southern breeds, Ayrshire and Friesian breeds, and Jersey. Grouping of Nordic breeds was supported by documented breed history and geographical divisions of native breeding regions of indigenous cattle. Divergence estimates between Icelandic cattle and indigenous breeds suggested a separation time of more than 1,000 years between Icelandic cattle and Norwegian native breeds, a finding consistent with historical evidence.
Alleles↗
Frequencies of genes for coat colour and horns in Nordic cattle breeds.
Gene frequencies of coat colour and horn types were assessed in 22 Nordic cattle breeds in a project aimed at establishing genetic profiles of the breeds under study. The coat colour loci yielding information on genetic variation were: extension, agouti, spotting, brindle, dun dilution and colour sided. The polled locus was assessed for two alleles. A profound variation between breeds was observed in the frequencies of both colour and horn alleles, with the older breeds generally showing greater variation in observed colour, horn types and segregating alleles than the modern breeds. The correspondence between the present genetic distance matrix and previous molecular marker distance matrices was low (r = 0.08 - 0.12). The branching pattern of a neighbour-joining tree disagreed to some extent with the molecular data structure. The current data indicates that 70% of the total genetic variation could be explained by differences between the breeds, suggesting a much greater breed differentiation than typically found at protein and microsatellite loci. The marked differentiation of the cattle breeds and observed disagreements with the results from the previous molecular data in the topology of the phylogenetic trees are most likely a result of selection on phenotypic characters analysed in this study.
Journal Article↗