Five regional localizations to the sheep genome: first assignments to chromosomes 5 and 12

The regional localization of five reference loci to sheep chromosomes is reported. The newly mapped loci are the T-cell receptor, beta ( TCRB ), coagulation factor X ( F10 ), laminin gamma 1 ( LAMC1 ), cyclic GMP rod phosphodiesterase, alpha ( PDEA ) and fibroblast growth factor 2 ( FGF2 ). The assignments of PDEA and LAMC1 to chromosomes 5q23–q31 and 12q22–q24 respectively provide the first markers physically assigned to these chromosomes. They also allow the provisional assignment of sheep syntenic group U19 to chromosome 5 and U1 to chromosome 12. The mapping of FGF2 to chromosome 17q23–q25 anchors the unassigned linkage group 'A' to chromosome 17, and the assignment of TCRB to chromosome 4q32–qter facilitates the orientation of a linkage group on sheep chromosome 4. The mapping of F10 to sheep chromosome 10q23–qter supports the recent assignment of bovine syntenic group U27 to cattle chromosome 12, as sheep chromosome 10 and cattle chromosome 12 are banded homologues.     

Assignment of the HOX2 and HOX3 gene clusters to the bovine chromosome regions 19q17-qter and 5q14-23

The homeobox 2 (HOX2) and homeobox 3 (HOX3) clusters have been chromosomally assigned in cattle by in situ hybridization. The probes employed were a murine probe for the mapping of HOX2 to 19q17-qter and human probes for the mapping of HOX3 to 5q14-q23. These assignments confirm the chromosomal assignment of two syntenic groups, consisting of loci located on human chromosome 12 (bovine chromosome 5) and the long arm of human chromosome 17 (bovine chromosome 19).     

Synteny mapping in the bovine: genes from human chromosome 5.

In an effort to generate a more complete bovine syntenic map of Type I comparative anchor loci, seven homologs to genes found on HSA5 were mapped using a panel of bovine x rodent hybrid somatic cells. Five HSA5 genes, CSF2, RPS14, PDGFRB, FGFA, and CSF1R, were assigned to bovine syntenic group U22 (chromosome 7), while two others, C9 and HGMCR, mapped to U10 and U5, respectively. Previous studies had assigned the HSA5 marker SPARC to bovine syntenic group U22. The mapping of genes spanning the length of HSA5 in cattle and also in mouse permits syntenic comparisons between prototypic genomes of three mammalian orders, providing insight into the evolutionary history of this region of the ancestral mammalian genome.     

Syntenic conservation between humans and cattle. II. Human chromosome 12

Bovine X hamster and bovine X mouse hybrid somatic cells have been used to investigate the syntenic relationship of nine loci in the bovine that have homologous loci on human chromosome 12. Eight loci, including A2M, GLI, HOX3, IFNG, INT1, KRAS2, NKNB, and PAH, were assigned to the previously identified bovine syntenic group U3 represented by GAPD. However, a single locus from the q-terminus of HSA 12, ALDH2, mapped to a new, previously unidentified autosomal syntenic group. These results indicate the existence of a very large ancestral syntenic group spanning from the p-terminus to q24 of HSA 12 and containing over 4% of the mammalian genome. Additionally, the results predict that ALDH2 is distal to PAH and IFNG on HSA 12, the type II keratin gene complex will reside between q11 and q21 of HSA 12, A2M will map to MMU 6, and LALBA and GLI will map to MMU 15.     

Gene assignment in the spider monkey (Ateles paniscus chamek--APC): APE-MYH7 to 2q; AR-GLA-F8C to the X chromosome.

Comparative gene assignment between the spider monkey species Ateles paniscus chamek (APC) and man (HSA) showed conserved syntenic associations despite extensive karyotypic rearrangement between species. Two HSA 14q genes were allocated to APC 2q, being syntenic to other HSA 14q and HSA 15q markers previously assigned to APC 2q, and to HSA 12q genes previously assigned to APC 2p. These findings were consistent with A. geoffroyi chromosome painting with human whole-chromosome probes, indicating that the genus Ateles is karyotypically very rearranged. On the other hand, three human X-linked markers were assigned to the Ateles X chromosome, indicating that this chromosome is evolutionary stable.     

Somatic cell mapping and restriction fragment analysis of bovine genes for fibronectin and gamma crystallin

DNAs from cow-hamster and cow-mouse somatic hybrid cells segregating bovine chromosomes have been analyzed by Southern blotting and hybridization with human fibronectin and gamma crystallin probes. Concordancy of retention of these bovine genes was compared to cattle isozyme loci representing previously described syntenic groups. Bovine fibronectin (FNI) and gamma crystallin (CRYG) fragments were concordant with each other and with isocitrate dehydrogenase 1 (IDH1), representing the bovine syntenic group U17. The syntenic relationship of these genes is conserved on human chromosome 2q and also on mouse chromosome 1. In addition, bovine RFLPs were identified with both fibronectin and gamma crystallin probes. These polymorphisms will be used to study recombination between the syntenic loci in pedigreed herds and to mark a segment of the bovine genome that is likely homologous to the Lsh region of mouse chromosome 1, which confers resistance in mice to several intracellular parasites.     

Chromosomal localization and detection of DNA polymorphisms in the bovine polymeric immunoglobulin receptor gene

Polymeric immunoglobulin receptor (PIGR) mediates transcellular transport of secretory antibodies in glandular and mucosal epithelial cells. By use of a bovine-rodent somatic cell hybrid panel the bovine PIGR locus has been assigned to syntenic group U1. Using in situ hybridization, PIGR was localized to bovine chromosome 16, segment q13, thus confirming the recent assignment of syntenic group U1 to this chromosome. Two common restriction fragment length polymorphisms (RFLPs) with the enzymes Bam HI and MspI were detected using the PIGR cDNA as probe. Direct PCR sequencing of a segment in the PIGR coding region (nucleotides 162–413) from 13 bulls of Norwegian Cattle revealed single nucleotide exchanges at two positions. An efficient PCR-RFLP method for detection of these mutations was developed.     

Syntenic assignments of visual transduction genes in cattle.

To establish syntenic relationships of phototransduction genes, we have mapped the genes encoding the alpha-, beta-, and gamma-subunits of rod cGMP phosphodiesterase (PDE) (PDEA, PDEB, PDEG), the alpha'-subunit of cone PDE (PDEA2), and the rod cGMP-gated channel (CNCG) to bovine syntenic groups. The rod cGMP PDE alpha-, beta-, and gamma-subunit genes map to bovine syntenic groups U22, U15 (chromosome 6), and U21 (chromosome 19), respectively. The rod cGMP-gated channel gene also maps to syntenic group U15, and the bovine cone alpha'-subunit gene maps to U26 (chromosome 26). With the exception of the cone PDE alpha'-subunit gene, which has not been mapped in other mammals, all of these genes have been assigned to conserved chromosomal regions shared among bovine, human, and mouse. A compilation of currently known syntenic assignments and predictions regarding future assignments of phototransduction genes in human, mouse, and cattle is presented.     

Assignment of five polymorphic ovine microsatellites to bovine syntenic groups

A panel of bovine somatic cell hybrids was used to map ovine microsatellites. Five of seven microsatellites were assigned to five bovine syntenic groups. These microsatellites were designated D5S10 (MAF23), D1S4 (MAF46), D13S1 (MAF18), D4S3 (MAF50), and DXS2 (MAF45), mapped to syntenic groups U3 (chromosome 5), U10 (chromosome 1), U11, U13, and the X chromosome, respectively. Two remaining sheep microsatellites amplified rodent DNA in the hybrid somatic cell panel, and were not assigned to bovine syntenic groups. Assignment of ovine-derived microsatellites to bovine syntenic groups provides additional evidence of the usefulness of microsatellites for mapping closely related species. The use of ovine and bovine microsatellites will aid in development of comparative genomic maps for these two species.     

Somatic cell mapping of T-cell receptor CD3 complex and CD8 genes in cattle

Bovine genes encoding T-cell receptor, CD3, and CD8 molecules have been mapped to syntetic groups using bovine × rodent hybrid somatic cells. T-cell receptor and chains were assigned to bovine syntenic group U5, and the and genes were syntenic with each other and with markers on U13. CD3E and CD3D genes were syntenic with each other and located to bovine syntenic group U19. CD8 was most concordant with markers of syntenic group U16, although the concordancy was only 85% and the assignment must be regarded as tentative. The comparative gene maps of human chromosome 7, bovine syntenic group U13, and mouse chromosomes 6 and 13 suggest extensive evolutionary conservation.     

Syntenic conservation of HSP70 genes in cattle and humans

A phage library of bovine genomic DNA was screened for hybridization with a human HSP70 cDNA probe, and 21 positive plaques were identified and isolated. Restriction mapping and blot hybridization analysis of DNA from the recombinant plaques demonstrated that the cloned DNAs were derived from three different regions of the bovine genome. One region contains two tandemly arrayed HSP70 sequences, designated HSP70-1 and HSP70-2, separated by approximately 8 kb of DNA. Single HSP70 sequences, designated HSP70-3 and HSP70-4, were found in two other genomic regions. Locus-specific probes of unique flanking sequences from representative HSP70 clones were hybridized to restriction endonuclease-digested DNA from bovine-hamster and bovine-mouse somatic cell hybrid panels to determine the chromosomal location of the HSP70 sequences. The probe for the tandemly arrayed HSP70-1 and HSP70-2 sequences mapped to bovine chromosome 23, syntenic with glyoxalase 1, 21 steroid hydroxylase, and major histocompatibility class I loci. HSP70-3 sequences mapped to bovine chromosome 10, syntenic with nucleoside phosphorylase and murine osteosarcoma viral oncogene (v-fos), and HSP70-4 mapped to bovine syntenic group U6, syntenic with amylase 1 and phosphoglucomutase 1. On the basis of these data, we propose that bovine HSP70-1,2 are homologous to human HSPA1 and HSPA1L on chromosome 6p21.3, bovine HSP70-3 is the homolog of an unnamed human HSP70 gene on chromosome 14q22-q24, and bovine HSP70-4 is homologous to one of the human HSPA-6,-7 genes on chromosome 1.     

Synteny mapping in the bovine: genes from human chromosome 4.

Genes homologous to those located on human chromosome 4 (HSA4) were mapped in the bovine to determine regions of syntenic conservation among humans, mice, and cattle. Previous studies have shown that two homologs of genes on HSA4, PGM2 and PEPS, are located in bovine syntenic group U15 (chromosome 6). The homologous mouse genes, Pgm-1 and Pep-7, are on MMU5. Using a panel of bovine x hamster hybrid somatic cells, we have assigned homologs of 11 additional HSA4 loci to their respective bovine syntenic groups. D4S43, D4S10, QDPR, IGJ, ADH2, KIT, and IF were assigned to syntenic group U15. This syntenic arrangement is not conserved in the mouse, where D4s43, D4s10, Qdpr, and Igj are on MMU5 while Adh-2 is on MMU3. IL-2, FGB, FGG, and F11, which also reside on MMU3, were assigned to bovine syntenic group U23. These data suggest that breaks and/or fusions of ancestral chromosomes carrying these genes occurred at different places during the evolution of humans, cattle, and mice.     

Genomic analysis of the major bovine milk protein genes.

The genomic arrangement of the major bovine milk protein genes has been determined using a combination of physical mapping techniques. The major milk proteins consist of the four caseins, alpha s1 (CASAS1), alpha s2 (CASAS2), beta (CASB), and kappa (CASK), as well as the two major whey proteins, alpha-lactalbumin (LALBA) and beta-lactoglobulin (LGB). A panel of bovine X hamster hybrid somatic cells analyzed for the presence or absence of bovine specific restriction fragments revealed the genes coding for the major milk proteins to reside on three chromosomes. The four caseins were assigned to syntenic group U15 and localized to bovine chromosome 6 at q31-33 by in situ hybridization. LALBA segregated with syntenic group U3, while LGB segregated with U16. Pulsed-field gel electrophoresis confirmed genetic mapping results indicating tight linkage of the casein genes. The four genes reside on less than 200 kb of DNA in the order CASAS1-CASB-CASAS2-CASK. Multiple restriction fragment length polymorphisms were also found at the six loci in three breeds of cattle.     

Mapping of bovine prolactin and rhodopsin genes in hybrid somatic cells

The genes encoding bovine prolactin and rhodopsin were assigned to syntenic groups on the basis of hybridization of DNA from a panel of bovine-hamster hybrid somatic cell lines with cloned prolactin and rhodopsin gene probes. Prolactin was found to be syntenic with previously mapped glyoxalase, BoLA and 21-hydroxylase genes, establishing a syntenic conservation with human chromosome 6. The presence of bovine rhodopsin sequences among the various hybrid cell lines was not concordant with any gene previously assigned to one of the 23 defined autosomal syntenic groups. Thus, rhodopsin marks a new bovine syntenic group, U24, leaving only five cattle autosomes unmarked by at least one biochemical or molecular marker.     

Regional localization of the fibronectin and gamma-crystallin genes to bovine chromosome 8

The genes for isocitrate dehydrogenase-1, fibronectin, and gamma-crystallin are syntenic in man, mouse, and cow. In an effort to assign this bovine syntenic group to a specific chromosome and to allow a cytological comparison of the conserved chromosomal region containing these genes in their respective species, we have localized the fibronectin and gamma-crystallin genes to bovine chromosome 8, region 1.1-1.4. This study incorporates the techniques of hybrid somatic cell analysis and in situ hybridization and the use of a Robertsonian-translocated marker chromosome from a related species for regional assignment of genes to a specific bovine chromosome. The regions on human chromosome 2q, mouse chromosome 1, and cow chromosome 8 that contain these genes are cytologically similar, perhaps representing evolutionary conservation at the cytogenetic level as well as at the gene level for this group of loci.     

Four human Chromosome 3q and four human Chromosome 21 loci map onto sheep Chromosome 1q

Eight new loci have been assigned to sheep Chromosome (Chr) 1q by use of a chromosomally characterized minipanel of sheep x hamster cell hybrids. Four loci, which have been mapped to the distal region of human Chr 3q, are ceruloplasmin (CP), sucrase isomaltase (SI), glucose transporter 2 (GLUT2), and ectopic viral integration site 1 (EVI1). The other four loci, on human Chr 21, include interferon alpha receptor (IFNAR); interferon inducible protein p78, murine (MX1); collagen type VI, alpha 1 (COL6A1); and S100 protein, beta polypeptide (S100B). All of these loci, except GLUT2 and MX1, have been mapped onto bovine Chr 1 or are syntenic with loci on this chromosome. The in situ localization of transferrin (TF) to sheep Chr 1q42-q45 confirms our previous assignment of this locus and independently anchors the eight new syntenic loci to sheep Chr 1q.     

Synteny mapping of human chromosome 8 loci in cattle

Four genes having homologous loci on the short arm of human chromosome 8 have been mapped to two different bovine syntenic groups. The gene coding for the tissue-type plasminogen activator mapped with GSR, a human chromosome 8 marker, of syntenic group U14 while lipoprotein lipase and the medium and light neurofilament polypeptide genes were shown to be syntenic with the human chromosome 9 marker GGTB2 of syntenic group U18.     

Assignment of bovine synteny group U2 to chromosome 9

One cosmid containing a microsatellite (INRA144, D9S14) was assigned to bovine synteny group U2 by somatic cell genetics and localized to bovine chromosome 9q25 by fluorescent in situ hybridization. These results permitted the assignment of one more synteny group to a bovine chromosome. There are now 22 out of 31 bovine synteny groups which are related to a chromosome. The mapping data have been entered in the BovMap database, Jouy-en-Josas, France.     

Localization on pig chromosome 6 of markers GPI, APOE, and ENO1, carried by human chromosomes 1 and 19, using in situ hybridization

In the pig, the linkage group around the halothane gene (HAL), composed of S-GPI-HAL-H-A1BG-PGD, has been assigned to bands p1.2----q2.2 of chromosome 6. In man, ENO1-PGD and APOE-GPI constitute two syntenic groups situated on different chromosomes (1 and 19, respectively). Since GPI and PGD are linked in the pig, we have hybridized the human cDNA probes for ENO1 and APOE to pig chromosomes. These markers were assigned to pig chromosome 6, in the q2.2----q2.4 and cen----q2.1 regions, respectively, using in situ hybridization. Since GPI and APOE are situated in the same region, we combined the use of high resolution chromosome analysis and in situ hybridization to give a more precise localization in the q1.2 and q1.2----q2.1.2 regions of chromosome 6. A possible linear order of these genes is proposed.     

Syntenic conservation between humans and cattle. I. Human chromosome 9

Bovine X hamster hybrid somatic cells have been used to investigate the syntenic relationship of nine loci in the bovine that have homologous loci on human chromosome 9. Six loci, ALDH1, ALDOB, C5, GGTB2, GSN, and ITIL, were assigned to the previously identified bovine syntenic group U18 represented by ACO1, whereas the other three loci, ABL, ASS, and GRP78, mapped to a new, previously unidentified autosomal syntenic group. Additionally, a secondary locus, ABLL, which cross-hybridized with the ABL probe, was mapped to bovine syntenic group U1 with the HSA 1 loci PGD and ENO1. The results predict that ACO1 will map proximal to ALDH1; GRP78 distal to ITIL and C5; GSN proximal to AK1, ABL, and ASS on HSA 9; GRP78 to MMU 2; and ITIL and GSN to MMU 4.