The structure of a conserved region of porcine genome, represented in human genome by chromosome 17

Radiation mapping of nine genes (H3F3B, HLR1, MYL4, STAT5B, THRA1, TOP2A, MCP1, NF1, and MPO) to porcine chromosome 12 was carried out. Also, subchromosomal location of the NF1 gene along with the two loci containing the DNA sequences homologous to the DNA of the two human BAC clones was determined. The NF1 position was ascertained via microdissection of chromosome 12 with subsequent PCR amplification of the gene fragment with specific primers. BAC clones were mapped using FISH. Comparative analysis of the gene order in porcine chromosome 12 and in the homologous human chromosome 17 was performed. It was demonstrated that the gene orders in these chromosomes differed relative to the position of the MPO gene.     

Localization of vicilin genes via polymerase chain reaction on microisolated field bean chromosomes

A new technique is reported for the physical mapping of low copy DNA sequences on plant chromosomes. Individual chromosomes were microisolated and their DNA used as the target for the polymerase chain reaction in order to identify the chromosome carrying a specific gene sequence. The use of defined translocation chromosomes further refined the resolution of the method to a subchromosomal level. To demonstrate the applicability of the procedure genes have been localized coding for vicilin seed storage proteins on the field bean Vicia faba L. in a region which includes the centromere and the proximal parts of the short and the long arms of chromosome II.     

Six genes of the human connexin gene family coding for gap junctional proteins are assigned to four different human chromosomes

Connexin genes code for proteins that form cell-to-cell channels known as gap junctions. The genes for the known connexins 26, 32, 43, and 46 have been assigned to human chromosomes, 13, X, 6, and 13, respectively, by analysis of a panel of human-mouse somatic cell hybrids using rat cDNA probes. A pseudogene of connexin 43 that lacks an intron of the cx43 gene has been located on human chromosome 5. Furthermore, the genes of the two new connexins 37 and 40 have both been assigned to human chromosome 1. Thus the human chromosomes 1 and 13 each carry at least two different connexin genes. Their exact location on these chromosomes is not yet known. From our results subchromosomal assignments can be deduced for the human cx32 gene to Xq13-p11, the human cx37 gene as well as the human cx40 gene to 1pter-q12, and the human cx43 gene to 6q14-qter. The generation of the connexin multigene family from a hypothetical ancestral connexin gene is discussed.     

Human genes involved in lipolysis of plasma lipoproteins: mapping of loci for lipoprotein lipase to 8p22 and hepatic lipase to 15q21

We have used cDNA probes for lipoprotein lipase and hepatic lipase to determine the chromosomal and subchromosomal locations of the human genes for these lipolytic enzymes. Southern blot analysis of genomic DNA from 17 independent mouse-human somatic cell hybrids demonstrated the presence of the gene for human lipoprotein lipase on chromosome 8, whereas the gene for hepatic lipase was on chromosome 15. Regional mapping of the genes by in situ hybridization to human chromosomes indicated that the lipoprotein lipase gene (LPL) resides in the p22 region of chromosome 8, while hepatic lipase gene (HL) resides in the q21 region of chromosome 15. We previously reported, on the basis of nucleotide and amino acid homologies, that these genes are members of a gene family of lipases, and, thus, the present findings indicate that the members of this family are dispersed. The results are also of significance with respect to disorders involving deficiencies of the enzymes. In particular, they suggest that certain rare combined deficiencies of both enzymes do not involve mutations of the structural loci.     

Regional mapping of the human placental alkaline phosphatase gene (ALPP) to 2q37 by in situ hybridization

In order to determine the subchromosomal location of the gene for human placental alkaline phosphatase (ALPP; EC 3.1.3.1.), a cDNA probe encompassing most of the ALPP translated sequences was hybridized in situ to metaphase chromosomes. Our results confirm previous assignment of the gene to chromosome 2 and allow its regional mapping to band q37.     

The Structure of a Conserved Region of Porcine Genome,Represented in Human Genome by Chromosome 17

Radiation mapping of nine genes (H3F3B, HLR1, MYL4,STAT5B, THRA1, TOP2A, MCP1, NF1, and MPO) to porcine chromosome 12 was carried out. Also, subchromosomal location of the NF1 gene along with the two loci containing the DNA sequences homologous to the DNA of the two human BAC clones was determined. The NF1 position was ascertained via microdissection of chromosome 12 with subsequent PCR amplification of the gene fragment with specific primers. BAC clones were mapped using FISH. Comparative analysis of the gene order in porcine chromosome 12 and in the homologous human chromosome 17 was performed. It was demonstrated that the gene orders in these chromosomes differed relative to the position of the MPO gene.     

Use of PCR markers for mapping swine chromosome 12

Using PCR analysis of pig-mink and pig-Chinese hamster hybrid cell lines and heterologous and homologous primers of various types, chromosomal and subchromosomal mapping of genes TOP2A, THRA, BRCA1, GAS, HLR1, MYL4, LIS1, MCP1, ENO3, CRYB1, P4HB, STAT5B, and H3F3B to pig chromosome 12 was carried out. The efficiency of using different types of heterologous primers for pig chromosome mapping was compared.     

Cytological, genetic and evolutionary functions of chiasmata based on chiasma graph analysis.

The nature of the chiasma as a cytological parameter for analysing cross-over was reexamined quantitatively by an improved chiasma graph method. It was reconfirmed in Mus platythrix (n =13) that interstitial chiasmata at diakinesis are distributed randomly and almost uniformly along bivalents except for the centromere and telomere regions. The size of these chiasma blank regions was consistently 0.8% of the total length of haploid autosomes in all chromosomes. There was a minimum value of chiasma interference distance between two adjacent chiasmata, which was constantly 1.8% in all chromosomes. The chiasma frequency at diakinesis was 20.1+/-2. 0 by the conventional method including terminal chiasmata. However, the primed in situ labeling technique revealed that terminal chiasmata were mostly telomere-telomere associations. From these data and also from recent molecular data we concluded that the terminal chiasma is cytologically functional for ensuring the normal disjunction of bivalents at anaphase I, but genetically non-functional for shuffling genes. The chiasma frequency excluding terminal chiasmata was 14.6+/-1.8. Reexamination of the chiasma frequency of 106 animal species revealed that the chiasma frequency increased linearly in proportion to the haploid chromosome number in spite of remarkable difference in their genome size. The increase in chiasma frequency would be evolution-adaptive, because gene shuffling is expected to be accelerated in species with high chromosome numbers.     

Anchoring of genetic linkage maps to the chromosome complement of Vicia faba L.

Using amplification of marker sequences with DNA from a set of distinct microdissected Vicia faba L. chromosomes covering the entire genome, we could unambiguously show that the linkage group I.B, which includes the pseudogene of legumin B4 (ψ1) and was previously ascribed to the metacentric chromosome I, actually belongs to chromosome IV. By considering the breakpoints of the translocated BKH chromosomes III and IV, even the subchromosomal position of loci LG085 and CNGC4 could be inferred. Anchoring all linkage groups to distinct faba bean chromosomes will facilitate quantitative trait locus fine mapping and gene identification using synteny, and will boost the development of efficient markers for selection in breeding programs.     

Gene-rich chromosome regions and autosomal trisomy

Summary Cases of autosomal trisomy and trisomy mosaicism among liveborn infants are reviewed, and a second case of chromosome 3 trisomy mosaicism is described. The occurrence of autosomal trisomy for a particular chromosome is in general negatively correlated with the number of genes which have been localized to that chromosome. It is also positively related to the Q-brightness of the chromosome, which reflects its content of intercalary heterochromatin. Furthermore there are significantly fewer autosomal trisomics for chromosomes which contain hot spots for mitotic chiasmata in Bloom syndrome (chromosomes 1, 3, 6, 11, 12, 17, 19, and 22), compared with similar-sized control chromosomes 2, 4, 7, 9, 10, 18, 20, and 21. This is interpreted as further evidence for the gene richness of the hot spots which, being active, are extended in interphase and are therefore available for mitotic crossing over. The gene richness of these short Q-dark regions is also borne out by the scarcity of trisomic abortions for the chromosomes involved (the embryo dies before the abortion is recognized) and by the higher number of genes localized to these chromosomes compared with the control chromosomes.     

Genome mapping in silver fox. Syntenic genes in Carnivora

Hamster X fox somatic cell hybrids segregating individual fox chromosomes in different combinations were used to assign seven structural loci to fox chromosomes. The gene for ME1 was mapped on the VFU1 chromosome, the genes for ADK and PP being located on the VFU4 chromosome. The gene for GSR was assigned to the VFU7 chromosome and the genes for MPI and COT1 were assigned to the VFU15 chromosome. Localization of these genes enhances the established fox genetic map and extends the known syntenic homologies between the fox and other mammalian. The comparison of data on gene mapping has provided basis for suggestion that there are significant differences in rates of karyotypic evolution in many mammalian taxa.     

A large inverted duplication allows homologous recombination between chromosomes heterozygous for the proximal t complex inversion

We have examined the molecular organization of a region of mouse chromosome 17 that allows homologous recombination between wild-type and t haplotype chromosomes across a large inversion. We have used a combination of genetic mapping of restriction fragment length polymorphisms, molecular characterization of cloned regions isolated on overlapping cosmids, and subchromosomal restriction mapping using the pulsed field gel technique. Our analyses show that the wild-type form of chromosome 17 contains an inverted duplication of an element of at least 650 kb that is present in only one copy in the t haplotype form. Two chromosomes, th45 and tAE5, arose by homologous recombination across the element that is present in both chromosomal variants in the same orientation.     

Assignment of the human urokinase receptor gene (PLAUR) to 19q13.

Through in situ hybridization of a cDNA probe to metaphase chromosomes, we localized the gene for the human urokinase receptor (PLAUR) on chromosome 19. RBG-banding permitted subchromosomal localization of the PLAUR gene to 19q13.     

Distribution of chiasmas in the 2d and 6th chromosomes involved in Robertsonian translocations in male mice

The distribution of chiasmata in 2 and 6 chromosomes in males homozygous for Rb(2.6)4Iem and Rb(8.17)1Iem was studied. Chiasmata were shown to distribute along chromosomes non-randomly, exchanges occurring in telomeric regions. Chiasmata distribution is substantially different for the cases of one and two chiasmata per bivalent. The main cause for these differences is supposed to be strong positive chiasmata interference (the position of the first chiasma may determine the position of the second one). The centromere blocks this effect, so chiasma in one arm does not interfere with that in the second arm. It has been shown that the frequency of double exchanges depended on not only the distance between markers under study, but also on marker position in the chromosome.     

Physical characterization of the homoeologous group 5 chromosomes of wheat in terms of rice linkage blocks, and physical mapping of some important genes.

The wheat homoeologous Group 5 chromosomes were characterized physically in terms of rice linkage blocks using a deletion mapping approach. All three chromosomes, 5A, 5B, and 5D, were shown to have a similar structure, apart from the 4A-5A translocation on the distal end of chromosome arm 5AL. The physical mapping of rice markers on the deletion lines revealed that the whole of rice chromosome 9 is syntenous to a large block, proximal to the centromere, on the long arm. Likewise, a small segment of the distal end of the long arm showed conserved synteny with the distal one-third end of the long arm of rice chromosome 3. In between those conserved regions, there is a region on the long arm of the Group 5 chromosomes which shows broken synteny. The proximal part of the short arms of the Group 5 chromosomes showed conserved synteny with a segment of the short arm of rice chromosome 11 and the distal ends showed conserved synteny with a segment of rice chromosome 12. The physical locations of flowering time genes (Vrn and earliness per se) and the gene for grain hardness (Ha) on the Group 5 chromosomes were determined. These results indicate that comparative mapping using the deletion mapping approach is useful in the study of genome relationships, the physical location of genes, and can determine the appropriate gene cloning strategy.     

Conservation of avian Z chromosomes as revealed by comparative mapping of the Z-linked aldolase B gene

A chicken Z-linked BAC probe containing the aldolase B gene was used for fluorescence in-situ hybridization (FISH) mapping in four different avian species. The biotinylated BAC clone showed distinct unique hybridization sites on the structurally different Z chromosomes. This result, together with previous data, lends credence to the notion that, despite undergoing structural rearrangements, the gene content of the avian Z chromosome remained conserved during evolution. Our study also demonstrates the feasibility of using large genomic clones for comparative mapping of Z-linked genes in birds.     

Isolation of a human chromosome 14-only somatic cell hybrid: analysis using Alu and LINE-based PCR.

Interspecific somatic cell hybrids containing single human chromosomes are valuable reagents for localization of cloned genes and DNA fragments to specific chromosomes, for the development of chromosome-specific libraries, and for generation of hybrid cell lines containing subchromosomal regions. A CHO somatic cell hybrid containing a single, intact human chromosome 14 (MHR14) was developed and confirmed by LINE PCR amplification gel pattern, by Alu-517 PCR product dot blot hybridization, and by cytogenetic analysis. MHR14 will serve as the chromosome source for the development of a radiation map of human chromosome 14.     

Conservation of the syntenies between porcine chromosome 7 and human chromosomes 6, 14 and 15 demonstrated by radiation hybrid mapping and linkage analysis

Comparative mapping studies facilitate the identification of genes located in quantitative trait locus (QTL) regions in domestic animals by utilizing information from the human genome. Radiation hybrid (RH) mapping is effective for this purpose because of its high resolution in ordered gene mapping on chromosomes. We constructed an RH map of pig chromosome 7, by adding 23 markers associated with genes. This RH map clearly demonstrated the mosaic of homology between pig chromosome 7 (SSC7) and human chromosomes 6, 14 and 15 at a 'gene' level, and was confirmed by linkage analysis. Clarification of the homology of SSC7 to human chromosomes will contribute to the elucidation of the gene(s) responsible for QTL detected on this chromosome.     

Mapping genes affecting flowering time and frost resistance on chromosome 5B of wheat

Two populations of single chromosome recombinant lines were used to map genes controlling flowering time on chromosome 5B of wheat, and one of the populations was also used to map a new frost resistance gene. Genetic maps were developed, mainly using microsatellite markers, and QTL analysis was applied to phenotypic data on the performance of each population collected from growth-room tests of flowering time and frost tolerance. Using a recombinant substitution-line mapping population derived from a cross between the substitution-line 'Chinese Spring' ('Cheyenne' 5B) and 'Chinese Spring' (CS), the gene Vrn-B1, affecting vernalization response, an earliness per se locus, Eps-5BL1, and a gene, Fr-B1, affecting frost resistance, were mapped. Using a 'Hobbit Sib' ('Chinese Spring' 5BL) x 'Hobbit Sib' recombinant substitution line mapping population, an earliness per se locus, Eps-5BL2 was mapped. The Vrn-B1 locus was mapped on the distal portion of the long arm of chromosome 5B, to a region syntenous with the segments of chromosomes 5A and 5D containing Vrn-A1 and Vrn-D1 loci, respectively. The two Eps-5BL loci were mapped close to the centromere with a 16-cM distance from each other, one in agreement with the position of a homoeologous locus previously mapped on chromosome 5H of barley, and suggested by the response of 'Chinese Spring' deletion lines. The Fr-B1 gene was mapped on the long arm of chromosome 5B, 40 cM from the centromeric marker. Previous comparative mapping data with rice chromosome 9 would suggest that this gene could be orthologous to the other Fr genes mapped previously by us on chromosomes 5A or 5D of wheat, although in a more proximal position. This study completes the mapping of these homoeoallelic series of vernalization requirement genes and frost resistance genes on the chromosomes of the homoeologous group 5 in wheat.