Human elastin gene: new evidence for localization to the long arm of chromosome 7.

In this study we have utilized human elastin cDNAs in molecular hybridizations to establish the chromosomal location of the human elastin gene. First, in situ hybridizations were performed with metaphase chromosomes from phytohemagglutinin-stimulated human peripheral blood lymphocytes. In three separate experiments using two different regions of human elastin cDNAs, the distribution of grains was found to be concentrated on the long arm of chromosome 7 within the [q11.1-21.1] region, and the peak number of grains coincided with the locus 7q11.2. Second, hybridizations with a panel of human-rodent cell hybrids showed concordance with human chromosome 7. Third, PCR analyses with elastin-specific primers of DNA from a hybrid cell line containing chromosome 7 as the only human chromosome yielded a product of the expected size, while DNA containing human chromosome 2, but not chromosome 7, did not result in a product. The results indicate that the human elastin gene is located in the proximal region of the long arm of chromosome 7. The precise localization of the elastin gene in the human genome is useful in establishing genetic linkage between inheritance of an allele with a mutated elastin gene and a heritable disorder.     

Chromosome balance and the control of malignancy.

The Giemsa banding pattern of the chromosomes has been analyzed in a line of transformed golden hamster cells, revertant and re-revertant cells and their tumors. The transformed and re-revertant cells were malignant in vivo and had gained an additional chromosome 5(7). Revertants with a suppression of malignancy lost this additional chromosome 5(7) and gained an additional chromosome 7(2). The tumors produced by segregants from the revertant cells were malignant, although to a lower degree than transformed and re-revertant cells. These tumors had lost the additional chromosome 7(2) found in revertants and gained one or two 5(12) chromosomes. The results support the hypothesis that the balance between genes for expression and suppression controls malignancy. The data indicate that chromosome 7(2) carries genes for suppression and that chromosomes 5(7) and 5(12) carry genes for expression of malignancy. The genes on chromosome 5(7) seem to result in a greater degree of expression than the genes on chromosome 5(12). The chromosome balance that controlled malignancy in these cells, also controlled the expression and suppression of transformed properties in vitro.     

Physical map of the centromeric region of human chromosome 7: relationship between two distinct alpha satellite arrays.

A long-range physical map of the centromeric region of human chromosome 7 has been constructed in order to define the region containing sequences with potential involvement in centromere function. The map is centered around alpha satellite DNA, a family of tandemly repeated DNA forming arrays of hundreds to thousands of kilobasepairs at the primary constriction of every human chromosome. Two distinct alpha satellite arrays (the loci D7Z1 and D7Z2) have previously been localized to chromosome 7. Detailed one- and two- locus maps of the chromosome 7 centromere have been constructed. Our data indicate that D7Z1 and D7Z2 arrays are not interspersed with each other but are both present on a common Mlu I restriction fragment estimated to be 3500 kb and 5500 kb on two different chromosome 7's investigated. These long-range maps, combined with previous measurements of the D7Z1 and D7Z2 array lengths, are used to construct a consensus map of the centromere of chromosome 7. The analysis used to construct the map provides, by extension, a framework for analysis of the structure of DNA in the centromeric regions of other human and mammalian chromosomes.     

Consensus and comprehensive linkage maps of bovine chromosome 7

The objective of this project was to integrate the currently available linkage maps for bovine chromosome 7 (BTA7) by combining data sets from eight research groups. A total of 54 unique markers were typed in eight pedigrees. Multilocus linkage analysis with CRI-MAP produced a bovine chromosome 7 consensus framework map of 27 loci ordered with odds greater than 1000:1. Furthermore, we present a bovine chromosome 7 comprehensive map integrating 54 loci. The locus order is in general agreement with the recently published linkage maps except for one discrepancy. The order of loci BM9289, BMS713, and ILSTS001 was reversed in the consensus framework map relative to the published USDA-MARC bovine chromosome 7 linkage map.     

Identification and regional localization of DNA markers on chromosome 7 for the cloning of the cystic fibrosis gene

To facilitate mapping of the cystic fibrosis locus (CF) and to isolate the corresponding gene, we have screened a flow-sorted chromosome 7-specific library for additional DNA markers in the 7q31-q32 region. Unique ("single-copy") DNA segments were selected from the library and used in hybridization analysis with a panel of somatic cell hybrids containing various portions of human chromosome 7 and patient cell lines with deletion of this chromosome. A total of 258 chromosome 7-specific single-copy DNA segments were identified, and most of them localized to subregions. Fifty three of these corresponded to DNA sequences in the 7q31-q32 region. Family and physical mapping studies showed that two of the DNA markers, D7S122 and D7S340, are in close linkage with CF. The data also showed that D7S122 and D7S340 map between MET and D7S8, the two genetic markers known to be on opposite sides of CF. The study thus reaffirms the general strategy in approaching a disease locus on the basis of chromosome location.     

Assignment of MHC in swine to chromosome 7 by in situ hybridization and serological typing

Mapping of the MHC in swine (SLA) was achieved by direct in situ hybridization to chromosome preparations. We took advantage of the fact that the cDNA probe coding for class I HLA-B7 antigen cross-hybridizes with swine genomic DNA. By nick-translation, 35S nucleotides were incorporated to a specific activity of 2,7 10(7) cpm/ug. Analysis of 91 randomly selected labeled metaphases revealed highly significant labeling on chromosome 7. The SLA complex is most probably located at the proximal half of the long arm, as indicated in families carrying a modified chromosome 7 and heterozygous for SLA. The abnormal chromosome was always inherited with a specific haplotype whereas the other parental haplotypes were found in association with the normal 7.     

A molecular genetic linkage map of mouse chromosome 7

The homology between mouse chromosome 7 and human chromosomes 11, 15, and 19 was examined using interspecific backcross animals derived from mating C3H/HeJ-gld/gld and Mus spretus mice. In an earlier study, we reported on the linkage relationships of 16 loci on mouse chromosome 7 and the homologous relationship between this chromosome and the myotonic dystrophy gene region on human chromosome 19. Segregation analyses were used to extend the gene linkage relationships on mouse chromosome 7 by an additional 21 loci. Seven of these genes (Cyp2a, D19F11S1h, Myod-1, Otf-2, Rnu1p70, Rnu2pa, and Xrcc-1) were previously unmapped in the mouse. Several potential mouse chromosome 7 genes (Mel, Hkr-1, Icam-1, Pvs) did not segregate with chromosome 7 markers, and provisional chromosomal assignments were made. This study establishes a detailed molecular genetic linkage map of mouse chromosome 7 that will be useful as a framework for determining linkage relationships of additional molecular markers and for identifying homologous disease genes in mice and humans.     

Regional assignment of 41 human DNA fragments on chromosome 7 by means of a somatic cell hybrid panel

Summary To detect new restriction fragment length polymorphisms that would cover human chromosome 7 with a network of genetic landmarks, a chromosome 7-specific phage gene library was screened for human single-copy fragments. With use of a somatic cell hybrid panel containing defined regions of human chromosome 7, 41 cloned human single-copy sequences were assigned to five regions of this chromosome. Of special importance are the cell hybrid clones GM1059Rag5 and 7851Rag10-1, derived from human cells with interstitial deletions spanning the bands 7q22-q32, within which the cystic fibrosis gene is located. Twelve new probes are described in 7q22-q32, five of which detect a total of six RFLPs.     

The quantitative analysis of polymorphism on human chromosomes 1, 9, 16, and Y

Summary A paracentric inversion of chromosome 5 was detected after RHG banding in a subject affected by Klinefelter's syndrome. The inversion was also observed in the patient's mother, and was confirmed by QFQ-and RBA-banding techniques.A second paracentric inversion affecting chromosome 7 was detected in a woman with Turner's syndrome. The same structural anomaly was found in her father and her half-brother.The possible relationship between sex chromosome nondisjunction and paracentric inversion is discussed.Furthermore, the inversion of chromosome 7 reproduces exactly the chromosome 7 of the gorilla, which is presumed to be ancestral to the human 7. This therefore appears to be the first reported case of reverse chromosomal mutation.     

Paternal isodisomy for chromosome 7 is compatible with normal growth and development in a patient with congenital chloride diarrhea.

Uniparental disomy for maternal chromosome 7 has been described in three patients with recessive disorders. Short stature in each of these patients has been explained by the effect of imprinting of growth-related genes on maternal chromosome 7. Alternatively, although less likely, all these patients may be homozygous for a rare recessive mutation. Here we report both paternal isodisomy for chromosome 7 and normal growth in a patient with a recessive disorder, congenital chloride diarrhea. She had inherited only paternal alleles at 10 loci and was homozygous for another 10 chromosome 7 loci studied. Her physical status and laboratory tests were normal except for a mild high-frequency sensorineural hearing loss. As the patient has normal stature, it is likely that the paternal chromosome 7 lacks the suggested maternal imprinting effect on growth. Paternal isodisomy for human chromosome 7 may have no phenotypic effect on growth.     

Genetic induction of chromosomal rearrangements in barley chromosome 7H added to common wheat

Chromosome 2C of Aegilops cylindrica induces chromosomal rearrangements in alien chromosome addition lines, as well as in euploid lines, of common wheat. To induce chromosomal rearrangements in barley chromosome 7H, reciprocal crosses were made between a mutation-inducing common wheat line that carries a pair of 7H chromosomes and one 2C chromosome and a 7H disomic addition line of common wheat. Many shrivelled seeds were included in the progeny, which was an indication of the occurrence of chromosome mutations. The chromosomal constitution of the viable progeny was examined by FISH (fluorescence in situ hybridization) using the barley subterminal repeat HvT01 as a probe. Structural changes of chromosome 7H were found in about 15% of the progeny of the reciprocal crosses. The aberrant 7H chromosomes were characterized by a combination of N-banding, FISH and genomic in situ hybridization. Mosaicism for aberrant 7H chromosomes was observed in seven plants. In total, 89 aberrant 7H chromosomes were identified in 82 plants, seven of which had double aberrations. More than half of the plants carried a simple deletion: four short-arm telosomes, one long-arm telosome, and 45 terminal deletions (23 in the short arm, 21 in the long arm, and one involving both arms). About 40% of the aberrations represented translocations between 7H and wheat chromosomes. Twenty of the translocations had wheat centromeres, 12 the 7H centromere, with translocation points in the 7HS (five) and in the 7HL (seven), and the remaining four were of Robertsonian type, three involving 7HS and one with 7HL. In addition, one translocation had a barley segment in an intercalary position of a wheat chromosome, and two were dicentric. The breakpoints of these aberrations were distributed along the entire length of chromosome 7H.     

Mapping of locus for X-linked congenital stationary night blindness (CSNB1) proximal to DXS7.

A recombinant chromosome in a male affected with X-linked congenital stationary night blindness (CSNB1) provides new information on the location of the CSNB1 locus. A four-generation family with five males affected with X-linked CSNB was analyzed with five polymorphic markers for four X-chromosome loci spanning the region OTC (Xp21.1) to DXS255 (Xp11.22). Four of the males inherited the same X chromosome; one male inherited a chromosome that from OTC to DXS7, inclusive, was derived from the normal X chromosome of his unaffected grandfather and that from a location between DXS7 and DXS426 proximally was derived from the chromosome carrying the CSNB1 locus. This recombinant maps the CSNB1 locus in this family to a region on the short arm of the X chromosome proximal to the DXS7 locus.     

Proliferation enhancement by spontaneous multiplication of chromosome 7 in rheumatic synovial cells in vitro

Mosaic trisomy of chromosome 7 is known to occur in a variety of non-neoplastic hyperproliferative disorders. In long-term cell cultures established from rheumatic synovium with mosaic trisomy 7, we observed a continuous increase in the proportion of cells with trisomy 7 to over 50% by the 10th in vitro passage. Simultaneous in situ hybridization with a repetitive chromosome-7-specific DNA probe and fluorescent Ki-67 labelling showed a strong correlation between trisomy 7 and an elevated proliferation index in cultured rheumatic synovial cells. Moreover, we observed a fraction of rapidly proliferating cells with up to eight copies of chromosome 7 as the sole cytogenetic change. Frequent somatic pairing of centromeres of two chromosomes 7 in interphase nuclei suggests either atypical non-disjunction with a persisting centromere or selective endoreduplication of chromosome 7.     

A microsatellite sequence from the rice blast fungus (Magnaporthe grisea) distinguishes between the centromeres of Hordeum vulgare and H. bulbosum in hybrid plants.

A TC/AG-repeat microsatellite sequence derived from the rice blast fungus (Magnaporthe grisea) hybridized to all of the centromeres of Hordeum vulgare chromosomes, but hybridized faintly or not at all to the chromosomes of Hordeum bulbosum. Using this H. vulgare centromere-specific probe, the chromosomes of four F1 hybrids between H. vulgare and H. bulbosum were analyzed. The chromosome constitution in the root tips of the hybrids was mosaic, i.e., 7 (7v, H. vulgare) and 14 (7v + 7b H. bulbosum), or 14 (7v + 7b) and 27 (14v + 13b), or 7 (7v), 14 (7v + 7b), and 27 (14v + 13b). The 27-chromosome tetraploid hybrid cells were revealed to have the NOR (nucleolus organizer region) bearing chromosome of H. bulbosum in a hemizygous state, which might indicate some role for this chromosome in the chromosome instability of the hybrid condition. The chromosomal distribution showed that the chromosomes of H. vulgare were concentric and chromosomes of H. bulbosum were peripheral in the mitotic squash. This non-random chromosome distribution and the centromere-specific repeated DNA differences in the two species were discussed in relation to H. bulbosum chromosome elimination. Meiotic chromosome analyses revealed a high frequency of homoeologous chromosome pairing in early prophase. However, this chromosome pairing did not persist until later meiotic stages and many univalents and chromosome fragments resulted. These were revealed to be H. bulbosum by fluorescence in situ hybridization (FISH) analysis with the H. vulgare centromere-specific probe. Because the chromosome segregation of H. vulgare and H. bulbosum chromosomes at anaphase I of meiosis was random, the possibility for obtaining chromosome substitution lines in diploid barley from the diploid hybrid was discussed.     

Structural organization of an alien Thinopyrum intermedium group 7 chromosome in U.S. soft red winter wheat (Triticum aestivum L.).

Barley yellow dwarf virus (BYDV) resistance in soft red winter wheat (SRWW) cultivars has been achieved by substituting a group 7 chromosome from Thinopyrum intermedium for chromosome 7D. To localize BYDV resistance, a detailed molecular genetic analysis was done on the alien group 7 Th. intermedium chromosome to determine its structural organization. Triticeae group 7 RFLP markers and rye specific repetitive sequences used in the analysis showed that the alien chromosome in the P29 substitution line has distinguishing features. The 350-480 bp rye telomeric sequence family was present on the long arm as determined by Southern and fluorescence in situ hybridization. However, further analysis using a rye dispersed repetitive sequence indicated that this alien chromosome does not contain introgressed segments from the rye genome. The alien chromosome is homoeologous to wheat chromosomes 7A and 7D as determined by RFLP analysis. Presence of the waxy gene on chromosomes 7A, 7B, and 7D but its absence on the alien chromosome in P29 suggests some internal structural differences on the short arm between Th. intermedium and wheat group 7 chromosomes. The identification of rye telomeric sequences on the alien Thinopyrum chromosome and the homoeology to wheat chromosomes 7A and 7D provide the necessary information and tools to analyze smaller segments of the Thinopyrum chromosome and to localize BYDV resistance in SRWW cultivars.     

Requirement of human chromosomes 19, 6 and possibly 3 for infection of hamster x human hybrid cells with baboon M7 type C virus.

The replication pattern of the endogenous baboon type C virus M7 was studied in 29 primary Chinese hamster × human hybrid clones generated with leukemic cells from two different patients with acute lymphoblastic or myeloblastic leukemia. There was no evidence of viral particulate RDDP or M7 antigen before viral infection. M7 virus replicated in human and some hybrid cells but not in Chinese hamster cells, indicating that M7 requires dominantly expressed human gene(s) for replication. Enzyme and cytogenetic analyses show that a gene(s) coded for by human chromosome 19 is necessary for M7 infection of these hybrids. Detailed cytogenetic correlations revealed, however, that the chromosome 19+/M7 + hybrid clones with intact chromosomes also had copies of chromosomes 3 and 6. Previously, Bevi, the putative integration site for M7 virus, has been assigned to human chromosome 6. Many clones with various combinations of chromosomes 3 and 6 lacked chromosome 19, however, and failed to replicate exogenously applied M7 virus, while tests of 27 secondary clones showed that M7 markers co-segregated with chromosome 19 markers. These findings all confirm the need for a chromosome 19-coded function in Chinese hamster × human hybrids. In addition, the yield of viral particulate RDDP produced into the culture fluid was 50–100 fold less per viral antigen-positive cell in the hybrids compared with human cells. Thus some form of regulation of viral components exists in the hybrid cells. When the virus replicating in hybrid cells was transferred back to human cells, this regulation was relaxed and the yield of RDDP per FA(+) cell greatly increased. We conclude that human chromosomes 6 and 19 code for functions involved in M7 virus metabolism, and we cannot exclude a function coded for by chromosome 3.     

Linkage and physical mapping of prolactin to porcine chromosome 7

Comparative mapping studies between human and pig have shown that there is conserved synteny between human chromosome 6 and pig chromosomes 1 and 7, but some gene locations are not well established. Prolactin ( PRL ), an anterior pituitary hormone, has been mapped to human chromosome 6, and has tentatively mapped to pig chromosome 7 using Southern-RFLP analysis with a limited number of meioses. To confirm the assignment of prolactin to porcine chromosome 7 by physical and linkage analysis, pig cDNA and human genomic DNA sequences were used to design pig-specific PCR primers. The primers amplified a fragment of ≈2·8 kb. Two polymorphic restriction sites were identified within this fragment with the restriction endonuclease Bst UI. Prolactin was significantly linked to six markers on the published PiGMaP map of pig chromosome 7. Prolactin was physically mapped using a pig × rodent somatic cell hybrid panel. An analysis of these data placed PRL on pig 7p1·1–p1·2 with 100% concordance and was in complete agreement with the linkage data. Both mapping techniques placed PRL in a conserved order with the loci in the syntenic region of human chromosome 6.     

Sublocalization of an invasion-inducing locus and other genes on human chromosome 7.

By somatic cell fusion studies between noninvasive mouse T-lymphoma cells and invasive human activated normal T-cells we have previously shown that the genetic information responsible for the induction of invasive and metastatic potential in interspecies T-cell hybrids is located on human chromosome 7. Apparently, genes derived from normal activated T-cells are dominantly expressed in the hybrids and control the invasive and, as a consequence, metastatic potential of these T-lymphoma cells. To sublocalize the invasion-inducing locus on chromosome 7 we have generated hybrids that harbor only specific regions of human chromosome 7 with or without a small fragment of human chromosome 21. Analysis of these hybrids revealed that the invasion-inducing locus maps to 7p12----cen. The human DNA complement of the hybrids was confirmed by Southern blot analysis using a large panel of chromosome 7-specific DNA probes. Several of these genes could be further sublocalized. These included: ARAF2 to 7p12----cen, D7S21 to 7pter----p12, ACTB to 7p15----p12, EGFR to 7p12, MDH2 to 7cen----q22, and PDGFA to 7pter----p15.     

Comparison of genetic and physical maps of group 7 chromosomes from Triticum aestivum L.

We present a high density physical map of homoeologous group 7 chromosomes from Triticum aestivum L. using a series of 54 deletion lines, 6 random amplified polymorphic DNA (RAPD) markers and 91 cDNA or genomic DNA clones from wheat, barley and oat. So far, 51 chromosome segments have been distinguished by molecular markers, and 54 homoeoloci have been allocated among chromosomes 7A, 7B and 7D. The linear order of molecular markers along the chromosomes is almost identical in the A- B- and D-genome of wheat. In addition, there is colinearity between the physical and genetic maps of chromosomes 7A, 7B and 7D from T. aestivum, indicating gene synteny among the Triticeae. However, comparison of the physical map of chromosome 7D from T. aestivum with the genetic map from Triticum tauschii some markers have been shown to be physically allocated with distortion in more distal chromosome regions. The integration of genetic and physical maps could assist in estimating the frequency and distribution of recombination in defined regions along the chromosome. Physical distance did not correlate with genetic distance. A dense map facilitates the detection of multiple rearrangements. We present the first evidence for an interstitial inversion either on chromosome arm 7AS or 7DS of Chinese Spring. Molecularly tagged chromosome regions (MTCRs) provide landmarks for long-range mapping of DNA fragments.