Assignment of the gene locus for human α-l-fucosidase to chromosome 1 by analysis of somatic cell hybrids

The -l-fucosidases (EC 3.2.1.51) from human and mouse cells could be separated by isoelectric focusing of neuraminidase-treated cell extracts in acrylamide slab gels. Fourteen hybrid clones derived from the fusion of mouse and human cultured fibroblasts and 37 hybrid clones derived from the fusion of human long-term lymphoid lines with mouse RAG cells were tested for expression of human -l-fucosidase. A strong correlation between the expression of the human enzyme and the presence or absence of human chromosome 1 was found. The presence of human -l-fucosidase in clones scored as positive by isoelectric focusing was confirmed by Ouchterlony double immunodiffusion against IgG from rabbits immunized with purified human -l-fucosidase. It is concluded that the structural gene locus for human -l-fucosidase is located on chromosome 1.     

Two cell-surface markers for human chromosome 1 in interspecies hybrids

Monoclonal antibodies AbAJ9 and AbT87 define two distinct human cell-surface antigen systems (1, 2). Both antibodies react with a wide variety of cultured human cell types but not with rodent cell lines. AbAJ9 identifies a glycoprotein of 140,000 mol wt and AbT87 identifies a glycoprotein of 60,000 mol wt. The genetic control of antigen expression was studied in rodent-human somatic cell hybrids containing different subsets of the entire human chromosome complement, using an immune rosetting assay for serological analysis and hybrid selection. The presence of human chromosome 1 was found to be both necessary and sufficient for expression of antigens AJ9 and T87 in hybrid cells. Two independent gene loci on chromosome 1, designated MSK-1 for AJ9 and MSK-2 for T87, control the expression of these antigens. We have assigned MSK-1 to region 1 cen-p22 and MSK-2 to region 1 q32-qter, using hybrids containing only fragments of human chromosome 1.     

应用光谱核型分析技术诊断复杂染色体畸变

目的探讨光谱核型分析技术（spectral karyotyping，SKY）在诊断复杂染色体畸变中的应用价值。方法选取4例常规G显带染色体核型分析未能确诊的染色体畸变病例，按SKY操作常规进行制片杂交，并通过相应的计算机软件分析结果。结果通过SKY技术，明确1例涉及3条染色体复杂易位病例的诊断；协助2例不明来源衍生染色体诊断为染色体自身的部分重复；但对染色体自身倒位和染色体畸变断裂点的诊断帮助不大。结论SKY技术对于诊断复杂的染色体易位或重排、微小的染色体结构畸变以及不明来源的衍牛染色体等方面有较大的优越性．是常规染仁．体核型分析的有益补充。     

Characterization of somatic cell hybrids by bivariate flow karyotyping and fluorescencein situ hybridization

We report on the use of flow karyotyping and fluorescence in situ hybridization (FISH) to characterize the human chromosomes in somatic cell hybrids. The identity, DNA content, and relative frequency of human chromosomes are derived from flow karyotypes, i.e., measurements of Hoechst and chromomycin fluorescence intensities of chromosomes by dual beam flow cytometry. Chromosome integrity is assessed by comparing the peak position of a human chromosome in the flow karyotypes of a hybrid cell line and its human donor. When human donor cells are unavailable, the peak position of a human chromosome in a hybrid line is compared to the range of peak positions among normal individuals. The relative frequency of human chromosomes in subclones or hybrids grown in culture is monitored using the volumes of peaks in flow karyotypes. FISH with biotinylated human genomic DNA or chromosome-specific repeat sequences as probe is used in conjunction with flow karyotyping to confirm the number of human chromosomes in hybrids. Some small rearrangements are detected by flow karyotyping and not by FISH. On the other hand, translocations between human and rodent chromosomes are detected by FISH and not always by flow karyotyping. Flow karyotyping and FISH were used to characterize over 100 hybrid lines donated by other laboratories. A hybrid set useful for the construction of chromosome-enriched gene libraries is presented. In this set, each of the 24 human chromosome types is present and intact, as judged by these techniques, in a line containing little or no other human material.     

Application of bacterial artificial chromosome array-based comparative genomic hybridization and spectral karyotyping to the analysis of glioblastoma multiforme

Identification of genetic losses and gains is valuable in analysis of brain tumors. Locus-by-locus analyses have revealed correlations between prognosis and response to chemotherapy and loss or gain of specific genes and loci. These approaches are labor intensive and do not provide a global view of the genetic changes within the tumor cells. Bacterial artificial chromosome (BAC) arrays, which cover the genome with an average resolution of less than 1 MbP, allow defining the sum total of these genetic changes in a single comparative genomic hybridization (CGH) experiment. These changes are directly overlaid on the human genome sequence, thus providing the extent of the amplification or deletion, reflected by a megabase position, and gene content of the abnormal region. Although this array-based CGH approach (CGHa) seems to detect the extent of the genetic changes in tumors reliably, it has not been robustly tested. We compared genetic changes in four newly derived, early-passage glioma cell lines, using spectral karyotyping (SKY) and CGHa. Chromosome changes seen in cell lines under SKY analysis were also detected with CGHa. In addition, CGHa detected cryptic genetic gains and losses and resolved the nature of subtle marker chromosomes that could not be resolved with SKY, thus providing distinct advantages over previous technologies. There was remarkable general concordance between the CGHa results comparing the cell lines to the original tumor, except that the magnitude of the changes seen in the tumor sample was generally suppressed compared with the cell lines, a consequence of normal cells contaminating the tumor sample. CGHa revealed changes in cell lines that were not present in the original tumors and vice versa, even when analyzed at the earliest passage possible, which highlights the adaptation of the cells to in vitro culture. CGHa proved to be highly accurate and efficient for identifying genetic changes in tumor cells. This approach can accurately identify subtle, novel genetic abnormalities in tumors directly linked to the human genome sequence. CGHa far surpasses the resolution and information provided by conventional metaphase CGH, without relying on in vitro culture of tumors for metaphase spreads.     

Assignment of a human gene for tryptophanyl-tRNA synthetase to chromosome 14 using human-mouse somatic cell hybrids

Human tryptophanyl-tRNA synthetase (Trp-RS, EC 6.1.1.2) can be separated from its mouse counterpart by Cellogel electrophoresis. Analysis of the presence or absence of human Trp-RS and other human enzyme markers in eleven independently derived cell lines of human-mouse somatic cell hybrids revealed that the expression of Trp-RS is correlated with the expression of human nucleoside phosphorylase (NP, EC 2.4.2.1). The syntenic relationship between Trp-RS and NP permits the assignment of the structural gene for Trp-RS to human chromosome 14. Karyotype and isozyme analysis of these hybrid clones rules out other linkage assignments.     

Characterization and use of somatic cell hybrids with interspecific translocations involving the human X chromosome

Two hybrid cell lines, whose only human material was a portion of the X translocated on to a mouse chromosome, have been characterized by cytogenetics, in situ hybridization and Southern blotting. In one hybrid (HORL911R8B) the region Xpter to Xq2(2–4) was identified. In the other (PIP) the single human fragment was found to contain sequences from two separate X chromosomal regions (corresponding approximately to Xp11.4–Xp22.1 and Xq26–Xqter). These two hybrids in combination with a third (WAG 8) retaining Xqter to Xp21 as a human X-autosome translocation chromosome, form a mapping panel for rapid subregional assignments to the human X chromosome. This mapping panel has been used to provide information about the order of DNA sequences derived from the X chromosome and to provide an assignment for an anonymous DNA segment, M201γ, to Xp11.4–Xp21.1.     

Expression of fragile X chromosome in human-rodent somatic cell hybrids

The fragile X chromosome, associated with a common form of X-linked mental retardation, is cytologically observed most often as a gap or fragile site near the distal end of the long arm in band Xq28. Expression of this site is variable and dependent upon lowered thymidylate pools. In order to examine the behavior of this fragile site in a foreign genetic background, interspecific somatic cell hybrids were isolated from crosses of hamster cells and lymphoblastoid cells derived from male patients with fragile X-linked mental retardation. Three hybrid cell lines containing the human X chromosome were analyzed. Following induction with 5-fluorodeoxyuridine, all three hybrids expressed the fragile site in approximately 10% of the metaphases examined. Our data indicate that expression of the fragile site in band Xq27 is dependent neither on the integrity of the human genome nor on the expression of human autosomal genes.     

Analysis of tumor suppressor gene on human chromosome 9 in mouse x human somatic cell hybrids

Deletions of the short arm of human chromosome 9 (9p) are common in human leukemia and solid tumors. The minimum region of overlap of these deletions, located between the interferon genes and the methylthioadenosine phosphorylase gene, is partially syntenic with a region of mouse chromosome 4 that has tumor suppressor activity. Somatic cell hybrids between tumorigenic, MTAP-deficient, mouse L cells, and MTAP-competent human cells containing either a normal copy of 9p or a 9p with a deletion involving band 9p21 were selected in culture conditions that require MTAP activity for continued growth. Somatic cell hybrids that contained a normal copy of 9p rarely formed tumors in nude mice. Cells from the rare tumors that grew had lost the normal 9p. Hybrid cells that contained a 9p with deletions formed tumors more frequently, and cells from these tumors retained the 9p deletion chromosome. These results provide evidence that a tumor suppressor gene (or genes) is located on human chromosome 9 within the region of deletion.     

An evaluation of the inactive mouse X chromosome in somatic cell hybrids

The expression of mouseZfx, Rps4, Ube1x, andXist was evaluated in hamstermouse somatic cell hybrids containing either an active or an inactive mouse X chromosome using polymerase chain reaction of reverse transcribed RNA (RT-PCR). The results showed thatZfx, Rps4, andUbe1x are expressed exclusively from the active mouse X, whileXist is expressed exclusively from the inactive X. These findings confirm the pattern of X inactivation for these mouse genes reported previously based on expression in somatic tissues of F₁ females from interspecific crosses. These results demonstrate the existence of differences between human and mouse X inactivation, as the corresponding human genes,ZFX, RPS4X, andUBE1 escape X inactivation.     

光谱染色体核型分析技术在胰腺癌研究中的应用

胰腺癌发病隐匿,仅20%左右的患者有手术机会,5年生存率不足5%,且发病率呈逐年上升趋势.寻找并确定可用于早期诊断的遗传学标记,是有效治疗胰腺癌的重要前提之一.     

Identification of an unusual marker chromosome by spectral karyotyping

We ascertained a newborn girl with multiple congenital anomalies including severe hypotonia, cardiovascular defects, hearing loss, central nervous system anomalies, and facial anomalies. The infant died at 12 days. Cytogenetic analysis showed a de novo supernumerary marker chromosome. Fluorescence in situ hybridization (FISH) with a combination of chromosome specific alpha-satellite probes and an all-human centromere probe failed to show hybridization to the marker, indicating that the marker chromosome lacked detectable alpha satellite sequences. Spectral karyotyping (SKY) was performed and showed that the marker was chromosome 15 in origin. This was confirmed by FISH with a 15q specific subtelomeric probe, which showed hybridization to both ends of the marker chromosome. Based on FISH information and G-banding pattern, the marker was determined to be an inverted duplication of 15q25-qter, leading to partial tetrasomy for chromosome 15. Although the marker chromosome lacked detectable centromeric alpha-satellite sequences, it seemed to have a functional centromere as it is mitotically stable. This observation is consistent with previous studies on acentric marker chromosomes, which suggested that the DNA sequence at the breakpoint could function similarly to alpha-satellite sequences once activated through marker formation. Am. J. Med. Genet. 80:368–372, 1998. © 1998 Wiley-Liss, Inc.     

Expression of human hepatic genes in somatic cell hybrids

Four diploid human cell types (lymphocytes, fibroblasts, amniotic fluid cells, and hepatocytes) were fused to mouse hepatoma cells, HH. HH synthesized and secreted several liver-specific gene products including albumin, transferrin, and alpha-fetoprotein. The resulting interspecific hybrids were compared to determine whether or not the pattern of human hepatic gene expression was similar when these various cells were fused with the mouse hepatoma line. The expression of six human hepatic genes was examined, including albumin, alpha-fetoprotein, ceruloplasmin, transferrin, alpha-l-antitrypsin, and haptoglobin. Albumin was most frequently expressed while alpha-fetoprotein was not detected in any of the hybrids studied. The patterns of expression of human serum proteins differed between the hybrid series. Hybrids derived from human fibroblasts produced primarily albumin, while those derived from lymphoblastoid cells and amniocytes had a higher frequency of clones secreting alpha-l-antitrypsin. The findings reported here suggest that the frequency of hybrid clones expressing human hepatic gene products and the array of proteins produced are influenced by the histogenetic state of the human parental cell type.     

Detection of unidentified chromosome abnormalities in human neuroblastoma by spectral karyotyping (SKY)

Spectral karyotyping (SKY) is a novel technique based on the simultaneous hybridization of 24 fluorescently labeled chromosome painting probes. It provides a valuable addition to the investigation of many tumors that can be difficult to define by conventional banding techniques. One such tumor is neuroblastoma, which is often characterized by poor chromosome morphology and complex karyotypes. Ten primary neuroblastoma tumor samples initially analyzed by G-banding were analyzed by SKY. In 8/10 tumors, we were able to obtain additional cytogenetic information. This included the identification of complex rearrangements and material of previously unknown origin. Structurally rearranged chromosomes can be identified even in highly condensed metaphase chromosomes. Following the SKY results, the G-banding findings were reevaluated, and the combination of the two techniques resulted in a more accurate karyotype. This combination allows identification not only of material gained and lost, but also of breakpoints and chromosomal associations. The use of SKY is therefore a powerful tool in the genetic characterization of neuroblastoma and can contribute to a better understanding of the molecular events associated with this tumor.     

The selection of somatic cell hybrids between human lymphoma cell lines

Somatic cell hybrids have been selected between three pairs of established human lymphoid cell lines producing pure lines of proliferating hybrid cells: Raji/Namalwa, Raji/Daudi, and Raji/BJAB. The hybrid cell lines have been characterized with respect to isozyme pattern, volume, and karyotype.Paper 1 of the series, Somatic cell hybrids between human lymphoma cell lines.     

Combined spectral karyotyping and DAPI banding analysis of chromosome abnormalities in myelodysplastic syndrome.

Spectral karyotyping (SKY) is a new molecular cytogenetic technique that allows simultaneous visualization of each chromosome in a different color. We have used SKY for comprehensive analysis of 20 myelodysplastic syndromes (MDSs) (13 primary MDSs, 3 therapy-related MDSs, and 4 acute leukemias developed from MDS, including 1 cell line established from a secondary leukemia), previously analyzed by G-banding. To locate the chromosomal breakpoints, DAPI-counterstained band images from all metaphases were transformed to G-band-like patterns. By using SKY, it was possible to identify the origin and organization of all clonal marker chromosomes (mar), as well as the origin of all abnormalities defined as additional material of unknown origin (add) or homogeneously staining regions (hsr) by G-banding. In total, SKY identified the chromosomal basis of 38 mar, add, and hsr, corrected 8 abnormalities misidentified by G-banding, and revealed 6 cryptic translocations in 5 cases. Total or partial chromosomal loss (mainly of -5/5q- and -7/7q-) is the most frequent cytogenetic abnormality in MDS. In 3 of 11 cases with -5/5q- and in 4 of 8 with -7/7q-, lost material was detected by SKY in unbalanced translocations. A total of 60 chromosomal losses were identified by G-banding in 16 cases with multiple chromosome abnormalities involving at least 3 chromosomes. For 26 of these losses (43%), SKY analysis suggested that the losses were not complete, but had been translocated to a variety of partner chromosomes. Moreover, SKY analysis revealed that a ring chromosome in a case of acute leukemia developed from MDS contained three to six segments that originated from chromosome 21 material. Fluorescence in situ hybridization showed the amplification of the AML1 gene on regions derived from chromosome 21, providing the first evidence of amplification involving this gene in MDS. Genes Chromosomes Cancer 26:336-345, 1999.     

Gene targeting for somatic cell manipulation: rapid analysis of reduced chromosome hybrids by Alu-PCR fingerprinting and chromosome painting.

The techniques of reverse genetics rely heavily on parasexual methods for manipulating the human genome. However, the application of somatic cell genetics is severely limited by the availability of suitable endogenous selectable markers in the genome. We have addressed this problem by targeting a universally selectable marker into a predetermined region of the genome, using a stringent selection for homologous recombination. Correct gene targeting to human chromosome 7q11 was screened for by Southern blotting and confirmed by fluorescent in situ hybridization. Reduced chromosome 7 hybrids were generated by chromosome mediated gene transfer and selection for the neo gene. The resultant transgenomes were characterized by a combination of L1 fingerprinting, locus specific marker analysis, Alu-PCR and chromosome 'painting'. Alu-PCR and L1 'fingerprints' are complementary and mutually consistent. Chromosome 'painting' reflects and extends the results obtained for specific marker co-transfer. Thus Alu-PCR 'fingerprinting' and 'painting' combine to rapidly provide an accurate picture of transgenome content and complexity. Gene targeting, chromosome tagging and subsequent isolation can be applied to any region of the genome for which a molecular probe is available.