Direct detection of repetitive,whole chromosome paint and telomere DNA probes by immunogold electron microscopy

Biotinylated repetitive, whole chromosome paint and telomere DNA probes were investigated at the electron microscope level after non-isotopicin situ hybridization and direct immunogold detection. The protocol described allowed the visualization of a biotinylated chromosome 1 specific satellite DNA probe in the light microscope without silver intensification. This sensitive method was exploited to analyse factors contributing to signal strength in immunogold chromosome painting. Furthermore, it allowed us to investigate the distribution of (TTAGGG)n telomere repeats in human metaphase chromosomes and interphase nuclei. Telomeric and internal (TTAGGG)n repeats were detected at high spatial resolution in human metaphase chromosomes. In the periphery of lymphocyte interphase nuclei, two types of telomere hybridization signals were observed. They differed remarkably in compactness, indicating two types of chromatin conformation present at the interphase telomeresin situ.     

Detection of Trisomy 12 and Centromeric Alterations in CLL by Interphase- and Metaphase-FISH

We have studied trisomy 12 in chronic lymphocytic leukemia (CLL) by fluorescence in situ hybridization (FISH) with an -satellite centromeric probe for chromosome 12 on both dividing and non-dividing cells. Trisomy for chromosome 12 was demonstrated in four of these patients (15.3%) using FISH on interphase cells. The percentage of trisomic cells ranged from 10% to 65% of nuclei. The hybridization signals in the trisomic and disomic nuclei were of a broadly similar size and nature. Interestingly, three of the remaining CLL patients, who exhibited disomy for chromosome 12, showed a marked difference in size of the hybridization signals in interphase nuclei. This was also demonstrated in metaphase spreads. In addition, metaphase FISH studies revealed a supernumerary marker chromosome in three out of 26 patients with CLL.     

Ordered mapping of three alpha satellite DNA subsets on human chromosome 22

We report the physical order of three alphoid DNA subsets on human chromosome 22 determined by a combination of low- and high-resolution cytological mapping. Multicolor fluorescencein situ hybridization was performed on metaphase chromosomes, interphase nuclei and extended chromatin preparations. The results visually demonstrate the presence of three distinct alphoid DNA domains at the centromeric region of chromosome 22. Two domains appear adjacent by extended chromatin hybridization, while the third one is separated by DNA that does not hybridize with any of our probes. Our data demonstrate the applicability of interphase mapping for ordering alpha satellite DNA repeat arrays. However, in our experiments, the relationship between the extremities of repeat arrays could only be studied by extended chromatin experiments.     

Detection of monosomy in interphase nuclei and identification of marker chromosomes using biotinylated alpha-satellite DNA probes.

Nonradioactive in situ hybridization with chromosome-specific highly repetitive DNA probes is a fast and easy method for the detection of the number of chromosome copies in nonmitotic cells. In this study, we report the use of four biotinylated probes of the human alpha-satellite family recognizing the (peri)centromeric regions of chromosomes 3, 10, 16, and 17. The reliability of the probes was tested by hybridizations to metaphase chromosomes and interphase nuclei of normal blood lymphocytes, which showed a two signal score in 85%-94% and 82%-86% of the cells, respectively. In situ hybridization experiments with nuclei and metaphase spreads derived from the LXFS-650 cell line indicated monosomy for chromosomes 10 and 16 and the presence of two derivative chromosomes 17. These results were in accordance with the cytogenetic data obtained with GTG-banding and confirmed the monoclonality of the cell line. Furthermore, with this method the origin of an unclassified marker chromosome could be identified as a derivative of chromosome 3. Our results show that fluorescence in situ hybridization can be a useful tool in cancer cytogenetics for the detection of numerical aberrations in interphase nuclei and for the classification of marker chromosomes in addition to conventional cytogenetic techniques.     

Detection and analysis of origin of i(12p), a diagnostic marker of human male germ cell tumors, by fluorescence in situ hybridization.

The i(12p) chromosome marker has been shown to be a diagnostic and prognostic marker of human male germ cell tumors (GCTs). An analysis of the i(12p) and chromosome 12 aneuploidy was performed in five primary cell cultures and three established cell lines derived from human male GCTs by fluorescence in situ hybridization (FISH) with a chromosome 12 centromere-specific alpha-satellite DNA probe. Distinct differences in the centromeric signals originating from the i(12p) and normal chromosome 12 were detected, which were found to be useful for unambiguous distinction between the i(12p) and normal chromosomes 12 at interphase as well as at metaphase in these cultures. This method can be used for rapid screening of large numbers of interphase cells, eliminating the main limitation of conventional karyotypic analysis, namely, frequent inability to obtain sufficient numbers of dividing cells in direct preparations or in short-term culture of fresh biopsies. Our analysis of chromosome 12 centromeric signal size along with karyotypic data and results of analysis of restriction fragment length polymorphisms (RFLPs) on 12q in four GCTs suggested that the i(12p)s are formed by nonreciprocal centromeric interchanges between nonsister chromatids of homologous chromosomes.     

Rapid differential diagnosis of myxoid liposarcoma by fluorescence in situ hybridisation on cytological preparations

In two cases of suspected myxoid liposarcoma, where chromosomal metaphase preparations were not available, fluorescence in situ hybridisation was performed on interphase nuclei of cytological preparations for the detection of the specific translocation, t(12;16), characteristic of this tumour and of trisomy 8, which is the most frequent secondary chromosome aberration. Probes directed against chromosomes 12 and 16 and against the centromeres of chromosomes 12 and 8 were hybridised on cell brushings and cytocentrifuge preparations. The finding of three painting domains of both chromosomes 12 and 16 and of only two signals with the centromeric probe directed against chromosome 12, suggested the presence of t(12;16) in both cases. In one case trisomy 8 was inferred from the occurrence of three centromere 8 signals. This approach can be used to detect specific chromosomal abnormalities when an urgent differential diagnosis is requested or when chromosome preparations are not available, or both.     

Interphase molecular cytogenetic analysis of epithelial ovarian carcinomas.

Karyotype information on ovarian carcinomas has been limited because the tumors are often difficult to culture and the resultant metaphases can have complex numerical and structural chromosomal anomalies. Fluorescent in situ hybridization is a rapid method of determining centromere copy number in metaphase cells and interphase nuclei. Fluorescent in situ hybridization was used to determine the numerical centromere complement of chromosomes X, 8, 12, and 17 and HER-2/neu gene amplification within interphase nuclei of 25 primary epithelial ovarian carcinomas. Touch preparations of the carcinomas were hybridized with two-color combinations of directly labeled alpha-satellite centromeric chromosome enumeration probes and a directly labeled HER-2/neu probe. Modal centromere copy numbers for each of the four chromosomes were used to determine numerical abnormalities relative to the flow cytometric DNA ploidy level for each tumor. Four cases were found to be normal with respect to the four chromosomes studied. In the remaining 21 cases a relative loss of chromosomes 17 (16 cases) and X (nine cases) and a relative gain of chromosomes 12 (10 cases) and 8 (nine cases) were the most common findings. In addition, the HER-2/neu gene was amplified in two of the 25 tumors. In conclusion, fluorescent in situ hybridization is an excellent method for rapid determination of numerical abnormalities and gene amplification in ovarian carcinomas.     

Chromosome healing by addition of telomeric repeats in wheat occurs during the first mitotic divisions of the sporophyte and is a gradual process

Alien gametocidal chromosomes cause extensive chromosome breakage prior to S-phase in the first mitotic division of gametophytes lacking the alien chromosome. The broken chromosomes may be healed either by addition of telomeric repeats in the gametophyte or undergo fusions to form dicentric or translocation chromosomes. We show that dicentric chromosomes undergo breakage–fusion–bridge (BFB) cycles in the first few mitotic divisions of the sporophyte, are partially healed before the germ line differentiation regimen, and are healed completely in the ensuing gametophytic stage. The gametocidal factor on chromosome 4M_g of Aegilops geniculata was used to induce dicentrics involving the satellite chromosomes1B and 6B of wheat, Triticum aestivum. The dicentrics 1BS·1BL-2AL·2AS and 6BS·6BL-4BL·4BS initiated BFB cycles that ceased 2 to 4 weeks after seed germination. At the end of the BFB cycles, we observed deficient 1B and 6B chromosomes with breakpoints in proximal regions of the 1BL and 6BL arms. The process of chromosome healing was analyzed in root tip meristems, at meiotic metaphase I, and in the derived progenies by fluorescence in-situ hybridization analysis using a telomeric probe pAtT4. The results show that chromosome healing in wheat occurs during very early mitotic divisions in the sporophyte by de-novo addition of telomeric repeats and is a gradual process. Broken chromosome ends have to pass through several cell divisions in the sporophyte to acquire the full telomeric repeat length.     

Visualization of interphase chromosomes in postmitotic cells of the human brain by multicolour banding (MCB)

Molecular cytogenetics offers the unique possibility of investigating numerical and structural chromosomal aberrations in interphase nuclei of somatic cells. Previous fluorescence in-situ hybridization (FISH) investigations gave hints of numerical chromosomal imbalances in the human brain, present as low-level mosaicism. However, as precise identification of aneuploidy rates in somatic tissues faces major difficulties due to the limitations of FISH using whole chromosome painting or centromeric probes, in this study low-level mosaicism in the human brain was addressed for the first time using microdissection-based multicolour banding (MCB) probe sets. We demonstrated that MCB is suitable for this application and leads to more reliable results than the use of centromeric probes in parallel on the same samples. Autosomes and the active X chromosome appear as discrete metaphase chromosome-like structures, while the inactive X chromosome is condensed in more than 95% of interphase nuclei. The frequency of stochastic aneuploidy was found to be 0.2–0.5% (mean 0.35%) per autosome pair, 2% for the X chromosome in the female brain, and 0.4% in the male brain, giving a cumulative frequency of aneuploidy of approximately 10% in the adult brain. Moreover, MCB as well as multi-probe FISH using centromeric probes revealed associated signals in a large proportion of brain cells (10–40%). While co-localized signals could not be discriminated from numerical chromosome imbalances after FISH using centromeric probes, interphase MCB allows such differentiation. In summary, MCB is the only approach available at present that provides the possibility of characterizing the chromosomal integrity of arbitrary interphase cell populations. Thus, cytogenetics is no longer limited in its application to dividing cells, which is a great step forward for brain research.     

Multiple repetitive DNA sequences in the paracentromeric regions of Arabidopsis thaliana L.

Nine repetitive DNA sequences, present in the haploid Arabidopsis thaliana genome in 7–300 copies, were hybridized in situ to metaphase and interphase chromosomes. Every sequence was detected on all five chromosome pairs, but was not evenly dispersed over the genome. Clusters of signals were found in particular regions of the centromeric heterochromatin, and each sequence showed a characteristic distribution pattern. Some sequences hybridized more strongly on different chromosomes, reflecting chromosome-specific amplification or the presence of homologous sequences. No hybridization signals could be detected on euchromatic regions. In situ hybridization on extended chromatin fibres showed that the pAL1 repeats are interrupted by another repetitive DNA sequence. A cosmid subclone (74A) contained a (GA)₃₈ microsatellite motif, and hybridization with a (GA) oligonucleotide revealed that most of the hybridization sites of 74A correspond to the distribution of this microsatellite motif. The results show that the paracentromeric heterochromatin of A. thaliana chromosomes is composed not only of the tandemly arranged 180-bp repeat family pAL1/pAtMr, but also of some other repetitive sequences, thus giving a better understanding of the organization of sequences at the centromeres of A. thaliana.This revised version was published online in November 2005 with corrections to the Cover Date.     

Benzene increases aneuploidy in the lymphocytes of exposed workers: a comparison of data obtained by fluorescence in situ hybridization in interphase and metaphase cells

Benzene is an established human leukemogen that increases the level of chromosome aberrations in lymphocytes of exposed workers. Numerical aberrations (aneusomy) can be observed by fluorescence in situ hybridization (FISH) in both interphase and metaphase cells. Whereas interphase FISH allows nondividing cells to be analyzed, one advantage of metaphase FISH is that it can also detect structural changes. The present study compares the abilities of metaphase and interphase FISH to detect aneusomy of chromosomes 7 and 8 in healthy benzene-exposed human subjects. Metaphase and interphase cells from the peripheral blood of 43 workers exposed to benzene (median = 31 ppm, 8-hr TWA) and 44 frequency-matched controls were analyzed by FISH. Normal diploid cells contained two hybridization signals, whereas those that were potentially monosomic contained one, trisomic 3 and tetrasomic 4. The frequency of cells with one hybridization signal for chromosome 7 in metaphase spreads rose from 2.72 +/- 0.19 (%, mean +/- SE) in controls to 3.79 +/- 0.63 in workers exposed to 31 or fewer ppm benzene and 5.9 +/- 0.85 in those exposed to more than 31 ppm (P(trend) < 0.0001). No similar dose-dependent increase in the frequency of cells with one hybridization signal was observed by interphase FISH, probably because of probe overlap artifact. Although significant dose-dependent increases in the frequency of cells with three hybridization signals for chromosome 7 were detected by both methods in the higher-exposed group, a larger, more significant difference was detected by metaphase FISH between controls and workers exposed to 31 or fewer ppm. Similar data were obtained for chromosome 8. Interphase and metaphase FISH were moderately correlated for three hybridization signals but not for one hybridization signal in chromosome 7 or 8. In general, metaphase FISH was more sensitive in detecting both monosomy and trisomy in the lymphocytes of exposed workers.     

Unusual distribution pattern of telomeric repeats in the shrews <Emphasis Type="Italic">Sorex araneus</Emphasis> and <Emphasis Type="Italic">Sorex granarius</Emphasis>

Sorex araneus and Sorex granarius are sibling species within the Sorex araneus group with karyotypes composed of almost identical chromosome arms. S. granarius has a largely acrocentric karyotype, while, in S. araneus, various of these acrocentrics have combined together by Robertsonian (Rb) fusions to form metacentrics, with the numbers and types of metacentrics differing between chromosomal races. Our studies on telomeric sequences in S. araneus and S. granarius revealed differences between chromosomes and between species. In S. araneus (the Novosibirsk race), hybridization signals were present on the telomeres of all the chromosomes after FISH with a PCR-generated telomeric probe. In addition, hybridization signals were observed at high frequencies in the pericentric regions of some but not all metacentrics formed by Rb fusion. There were fewer signals on those metacentrics formed earlier in the evolution of S. araneus. This suggests that S. araneus chromosomes retain at least some telomeric repeats during Rb fusion, but that these repeats are lost or modified over time. These results are critical for the interpretation of the well-studied hybrid zones between chromosomal races of S. araneus, given that Rb fission has been postulated in such hybrid zones and that the likelihood of Rb fission will relate to presence/absence of telomeric sequences at the centromeres of metacentrics. In S. granarius, there were strong signals at the proximal (centromeric) telomeres of the acrocentrics after FISH with a DNA telomeric probe. FISH with a PNA telomeric probe on S. granarius acrocentrics showed that the proximal telomeres were 213 kb on average, while the length of the distal telomeres was 3.8 kb on average. Two-colour FISH, using a telomeric DNA probe and a microdissected probe generated from the pericentric regions of the S. granarius chromosomes a and b, revealed regions on distinct chromatin fibres where telomeric and microdissected probes were colocalized or localized sequentially. The proximal telomeres of S. granarius are highly unusual both in their large size and their heterogeneous structure relative to the telomeres of other mammals.     

一种能精确检测人间期细胞核中21号染色体拷贝数的DNA探针

目的制备能精确检测人类间期细胞核中２１号染色体拷贝数的ＦＩＳＨ探针。方法利用万能引物ＰＣＲ法,从定位于人２１ｑ１１的ＹＡＣ克隆８８１Ｄ２分离制备ＤＮＡ探针,并用于与８例正常人和５例２１三体患者的外周血淋巴细胞中期相和间期核,及经细胞松弛素Ｂ（ｃｙｔｏｃｈａｌａｓｉｎＢ）诱导的双核细胞进行ＦＩＳＨ分析。结果该探针具有以下特点：（１）长度集中于３５０～７５０ｂｐ;（２）其靶序列位于２１号染色体长臂上且紧靠着丝粒;（３）特异性强;（４）杂交信号明亮,容易辨认;（５）对中期相及间期细胞核中２１号染色体的检出率分别高达９９．６０％和９８．４０％。结论制备的ＤＮＡ探针能精确检测人类间期细胞核中２１号染色体的拷贝数,且适用于细胞分裂时２１号染色体分离情况的研究     

Nature of B chromosomes in the harvest mouse Reithrodontomys megalotis by fluorescence in situ hybridization (FISH)

Using fluorescence in situ hybridization, we examined the characteristics of two types of B chromosomes in harvest mice of the genus Reithrodontomys. B chromosomes were interrogated with rDNA, telomeric repeat, LINE element and centromeric heterochromatin probes. The two types of B chromosomes share the following features: (a) telomeres present on the ends of both arms; (b) hybridization to LINE probes; (c) absence of hybridization to the ribosomal gene probes; (d) C-band-positive centromeric regions; and (e) euchromatic arms. They differ as follows: (a) the larger B element hybridizes to the centromeric heterochromatin (pMeg-1) probe whereas the smaller B element does not; (b) the amount of C-band-positive material is reduced in the smaller B chromosome relative to that present on the larger B chromosome; and (c) the smaller element is reduced in size by about a third. It is concluded that the larger B chromosome arose as a leftover centromere from centric fusion, whereas the smaller element has a different origin — perhaps as an intact fragment or as an amplified region from the A chromosomes. The presence of euchromatic regions on B chromosomes may account for their survival in the karyotype.This revised version was published online in November 2005 with corrections to the Cover Date.     

Telomeric and interstitial telomeric sequences in holokinetic chromosomes of Lepidoptera: Telomeric DNA mediates association between postpachytene bivalents in achiasmatic meiosis of females

Telomeres, besides their main role in the protection and maintenance of chromosome ends, have several other vital functions in the cell cycle. We studied their role in the achiasmatic meiosis of female Lepidoptera, insects with holokinetic chromosomes. By fluorescence in-situ hybridization (FISH) with the insect telomeric probe, (TTAGG) _n , we mapped the distribution of telomeric and interstitial telomeric sequences (ITS) in female meiotic chromosomes of two species, Orgyia antiqua with a reduced chromosome number (2n=28) and Ephestia kuehniella mutants, possessing a radiation-induced chromosome fusion in the genome (2n=59). In addition to the strong typical telomeric signals, O. antiqua displayed weaker hybridization signals in interstitial sites of pachytene bivalents. The observed ITS most probably reflect remnants of chromosomal rearrangements and support the hypothesis that the Orgyia karyotype had arisen by multiple fusions of ancestral chromosomes. On the other hand, the absence of ITS in the chromosome fusion of Ephestia indicated the loss of telomeres before the two original chromosomes fused. When the telomeric probe was amplified by enzymatic reaction with tyramid, the number of ITS observed increased in Orgyia, and a few ITS were also observed in several chromosomes of Ephestia but not in the fused chromosome. This suggests that the genomes of both species also contain ITS other than those originating from chromosome fusions. The analysis of female meiotic prophase I revealed non-homologous associations of postpachytene bivalents mediated by telomeric DNA, which were not observed in the pachytene stage. Surprisingly, in early postpachytene nuclei the telomeric associations also involved ITS, whereas later postpachytene nuclei displayed chains of bivalents interconnected only by true telomeres. This finding favours a hypothesis that telomeric associations between bivalents play a role in chromosome segregation in the achiasmatic meiosis of female Lepidoptera. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic effects of petroleum fuels: II. Analysis of chromosome loss and hyperploidy in peripheral lymphocytes of gasoline station attendants

Molecular cytogenetic methods were applied to investigate the effect of the occupational exposure to low concentrations of benzene and petroleum fuels on genomic stability. Twelve male gasoline station attendants (average benzene exposure of 0.32 mg/m³ as 8h TWA) and 12 age- and smoking-matched unexposed controls were selected for the study. The incidence of hyperploidy and polyploidy in peripheral lymphocytes was evaluated through in situ hybridization of interphase cells, harvested 24 hr after stimulation, with centromeric probes of chromosomes 7, 11, 18, and X. For half of the subjects, metaphases harvested 24 hr later were analyzed. The incidence of chromosome loss in vitro was determined in cytokinesis-blocked cells, harvested at 66 hr, through the hybridization of micronuclei with a pancentromeric probe. Ten thousand chromosomes (more than 200 metaphases equivalent) and 2,000 binucleated cells/person were scored for hyperploidy and micronucleus analysis, respectively. The results obtained did not show any exposure-related excess of hyperploidy or micronucleus formation. Conversely, the age of the subjects was significantly correlated with several markers of genomic instability, such as the incidence of chromosome X and chromosome 18 hyperploidy, total hyperploidy and polyploidy, and close to statistical significance with chromosome loss. Smoking habits did not appear to contribute significantly to the effects measured. The parallel analysis of hyperploidy and polyploidy in interphase nuclei in 24-hr cultures and in metaphase cells harvested 24 hr later showed basically similar incidences of aneuploid cells, indicating that no significant selection against hyperploid and polyploid types occurred during the first cell cycle in vitro. Environ. Mol. Mutagen. 32:130–138, 1998 © 1998 Wiley-Liss, Inc.     

Detection of karyotype changes in interphase cells: oligonucleotide-primed in situ labelling versus fluorescence in situ hybridization

Interphase cytogenetics is a rapidly developing technique which is usually performed by fluorescence in situ hybridization (FISH). Recently, oligonucleotide-primed in situ synthesis (PRINS) has become established as a method of labelling centromeric regions of chromosomes in metaphase spreads. We tested the suitability of PRINS in detecting the exact copy number of chromosomes 1, 3, 7 and 8 in intact interphase cells of 17 cytological preparations derived from normal and neoplastic tissues. Control procedures consisted in preparation of metaphase spreads of lymphocytes of healthy donors, conventional cytogenetics in some of the specimens, and omission of the primers or Taq polymerase from the reaction mixture. All specimens were additionally examined by FISH and analysed blind by two experienced observers. Both PRINS and FISH revealed a corresponding distribution of hybridization signals for all chromosomes examined in specimens of normal bone marrow (n = 5), normal liver cells (n = 5), three samples of acute nonlymphocytic leukaemia in which conventional chromosome analyses had shown monosomy 7 or trisomy 8, and in four hepatocellular carcinomas that displayed trisomy 1. Overall, statistical analysis revealed no significant difference in the signal distribution between the two techniques. Our results demonstrate that PRINS is as reliable as FISH for detecting chromosome copy numbers in interphase nuclei of intact cells. The PRINS method, however, is easier to perform, faster and less expensive, holding great potential for future applications in diagnostic pathology.     

Genomic distribution of 5' TTCCA 3' repeat motif and its diagnostic potential in human Y-chromosome-related anomalies

We have studied genomic distribution of a simple repeat motif 5' TTCCA 3' derived from the DYZ1 fraction of the human Y chromosome employing restriction fragment length polymorphism and in situ hybridization techniques. This has led us to develop a synthetic DNA based genetic marker specific to human genome. Randomly selected human genomic DNA from both sexes, digested with a total of 16 restriction enzymes, hybridized with OAT20Y probe comprising four repeat units of 5' TTCCA 3' motif failed to reveal fragment length polymorphisms. In contrast, with most of the enzymes, several multilocus monomorphic bands and with a few enzymes, smeary signals were detected. In situ hybridization of the OAT20Y probe with human chromosomes revealed grains on the long arm of the Y chromosome, whereas the X-chromosome and autosomes showed random distribution of the grains without any preferential labeling in the centromeric or telomeric regions. The OAT20Y probe uncovers a 3.4 kb isomorphic band exclusively in the human male DNA digested with Hae III enzyme. Using the OAT20Y probe, we have detected the presence of Y chromosome in mosaic cell populations of Turner's patients with dysgenetic gonads and high levels of LS/FSH. The presence of Y chromosome in these patients has been associated with an increased risk of gonadoblastoma. The OAT20Y probe offers sensitivity and accuracy for the detection of Y-chromosome-bearing cells in a mosaic cell population and, consequently, help in better management of the patients.     

Detection of an i(17q) chromosome by fluorescent in situ hybridization with a chromosome 17 alpha satellite DNA probe.

An isochromosome for the long arm of chromosome 17,i(17q), is frequently found as an additional chromosome aberration to the Ph with advanced disease in the chronic myelocytic leukemia (CML). We studied an i(17q) in blood samples from two patients with CML in blast crisis with a biotinylated chromosome 17 specific alpha satellite deoxyribonucleic acid probe. G-banded karyotypes of these patients showed a dicentric i(17q), dic(17)(p11.2). Fluorescence in situ hybridization (FISH) delineated one normal chromosome 17 and one i(17q) among metaphase chromosomes; the latter showed a dicentric pattern. In most interphase nuclei of both patients, two fluorescence spots were observed. In some interphase nuclei, including mature neutrophils, the dicentric chromosome was discernible by its size and shape of the fluorescent spots. Three fluorescent spots were observed in a small proportion of interphase cells, and existence of a subclone with two normal chromosome 17 and an i(17q) was confirmed by examining a large number of metaphase plates. The results of FISH provided us with information of numerical and structural aberrations of chromosome 17 in interphase cells.     

应用荧光原位杂交检测人喉癌中EGFR基因扩增

目的 检测人喉癌Ｈｅｐ－２细胞系和５个喉癌组织中表皮生长因子受体（ｅｐｉｄｅｒｍａｌ ｇｒｏｗｔｈ ｆａｃｔｏｒ ｒｅｃｅｐｔｐｒ,ＥＧＦＲ）基因扩增。方法 荧光原位杂交技术。结果 在Ｈｅｐ－２细胞和２例喉癌组织中期染色体和间期细胞核中,检测到明显的集中成簇和多个斑点分散排布的杂效信号,另３例喉癌组织间期细胞核中杂交信号未见增强或数目增加。结论 以正常二倍休 色体和间期细胞核为对照,在喉癌Ｈｅｐ－