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The behaviour of a multiple sex chromosome system in Dundocoris flavilineatus (Heteroptera: Aradidae: Carventinae) that originated by autosome-sex chromosome fusion.

The nominate subspecies of Dundocoris flavilineatus Jacobs occurs in indigenous evergreen forests over a wide area in KwaZulu-Natal and the Eastern Cape Province of South Africa. It has a chromosome number of 2n male = 28XY, which is the ancestral number for the genus. D. flavilineatus ndabeniensis, which comprises an isolated sibling population at Ndabeni forest in northern KwaZulu-Natal, possesses a multiple sex chromosome system, presumably a X1X2Y system and has a chromosome number of 2n male = 27X1X2Y. The system probably originated when an autosome and the Y-chromosome of the 28XY karyotype fused. In contrast to the situation previously described in the XY1Y2 system of D. nodulicarinus the autosomal and original Y-chromosome parts of the neo-Y chromosome seem to have a reciprocal influence on each other in terms of structure and staining intensity during prophase 1. The autosomal part of the neo-Y adopts a granulate, heteropycnotic, linear structure while the original Y part is less globular than usual in structure. The neo-X chromosome (= X2) behaves like, and stays isopycnotic with the autosomes. It is connected to the neo-Y by terminal association--probably a terminal chiasma. The sex chromosome system is post-reductional and a sex chromosome trivalent is present in all metaphase II cells. The origin and behaviour of the neo-X1X2Y sex chromosome system in D. flavilineatus ndabeniensis are described, discussed, illustrated with photomicrographs and compared to the XY1Y2 system in D. nodulicarinus. Idiograms of the karyotypes of the two subspecies of D. flavilineatus are also presented.

Animals↗

Detection of Y-chromosomal DNA with marker chromosomes in Turner's syndrome.

Patients with clinical features of Turner's syndrome may have a 45,X/46,X + mar or 46,X + mar karyotype. It is estimated that phenotypic females or intersexuals with a Y chromosome and gonadal dysgenesis have a 20% risk of developing gonadoblastoma, so it is crucial to know whether Turner's syndrome patients have a Y chromosome. We studied the chromosomal make-up of four patients with Turner's syndrome using the polymerase chain reaction (PCR). Nine Y-chromosomal loci including four loci (PABY, SRY, ZFY, DYS14) on the short arm, one loci (DYZ3) on the centromere, and four loci (DYS132, DYS1, DYZ1, DYZ2) on the long arm were amplified to determine the origin of marker chromosomes. Three patients were identified as having Y chromosome DNA. Patient 1 contained the presumed gonadoblastoma locus (DYS132) and a prophylactic gonadectomy was carried out. DNA extracted from dysgenetic gonads did not show Y chromosome DNA. A rapid, highly sensitive and isotope-free method for detection of abnormal Y chromosomes in Turner's syndrome patients has been developed. Chromosome in situ hybridization analysis is required to confirm the PCR results, to provide further evidence for molecular organization of these marker chromosomes.

Adult↗

Chromosomal mapping of 18S-28S rRNA genes and 10 cDNA clones of human chromosome 1 in the musk shrew (Suncus murinus).

The direct R-banding fluorescence in situ hybridization (FISH) method was used to map 18S-28S ribosomal RNA genes and 10 human cDNA clones on the chromosomes of the musk shrew (Suncus murinus). The chromosomal locations of 18S-28S ribosomal RNA genes were examined in the five laboratory lines and wild animals captured in the Philippines and Vietnam, and the genes were found on chromosomes 5, 6, 9, and 13 with geographic variation. The comparative mapping of 10 cDNA clones of human chromosome 1 demonstrated that human chromosome 1 consisted of at least three segments homologous to Suncus chromosomes (chromosomes 7, 10, and 14). This approach with the direct R-banding FISH method is useful for constructing comparative maps between human and insectivore species and for explicating the process of chromosomal rearrangements during the evolution of mammals.

Animals↗

Application of fluorescence in situ hybridisation to study the relationship between cytotoxicity, chromosome aberrations, and changes in chromosome number after treatment with the topoisomerase II inhibitor amsacrine.

Amsacrine (4'-(9-acridinylamino)methanesulphon-m-anisidide) is an antileukemic drug which inhibits topoisomerase II (topo II) enzymes. We studied effects of two concentrations of amsacrine on the GM10115A cell line. This is a Chinese hamster line containing a single human chromosome 4, which can be readily visualised using fluorescence in situ hybridisation (FISH). The low amsacrine concentration slowed cell growth but did not cause significant arrest in the G2 phase of the cell cycle, while a higher concentration caused more long-term effects on the growth of the cells and caused G2 arrest. Either concentration led to chromosomal fragments which were lost with increasing time after treatment, and chromosomal translocations which appeared stable for at least 8 days after treatment. At the low concentration, the loss or gain of a single chromosome was a common event. The higher concentration led to polyploid cells, usually containing an uneven number of chromosome 4. We propose two mechanisms for aneuploidy by amsacrine (or related topo II poisons), either of which can be readily detected using FISH. At low drug concentrations, aneuploidy may occur directly through, for example, a failure to resolve catenated chromatids prior to anaphase. However, there has been considerable interest in the role of the cell division control (cdc) kinase and cyclins in regulating the mammalian cell cycle, and these may also be involved in the response of cells to high concentrations of topo II poisons. Cdc2 proteins and cyclins are involved in coordinating diverse activities during the M phase of the cell cycle, including catalysis of chromosome condensation and reorganisation of microtubules to allow chromosome separation during mitosis. Chromosome damage by topo II poisons will lead to G2 arrest, which allows the cells time to repair the damage. During this time, cyclin A and cdc2 levels will fall, preventing the cell from entering mitosis and effectively resetting the clock to G1 and the ploidy to tetraploid. Aneuploid cells will derive from polyploid cells through loss of extra chromosomes.

Amsacrine↗

Molecular studies of the sex chromosomes in human testicular cancer: pronounced changes in X and Y chromosome dosage in some tumors.

Nine males with testicular germ cell tumors were studied by Southern blotting using probes recognizing different regions of the X and Y chromosomes. In the tumors of three patients, an imbalance was noted with a relative deficiency of DNA of Y-chromosomal and a concurrent excess of that of X-chromosomal origin. The X:Y signal ratios were 4, 4, and 2, respectively, in tumor DNA relative to normal DNA, and the ratios of Y to an autosomal locus were 0.4, 0.6, and 0.7, respectively, in the same tumors. Several loci on both arms of the Y chromosome were similarly involved. No structural abnormalities of Y chromosome DNA could be demonstrated. The X/Y change occurred in two of the three patients with nonseminomatous tumors and in two of the three patients with metastatic disease. To account for the results, two alternative models are discussed: first, loss of the Y chromosome and increase in X chromosome number in some but not all tumor cells; second, polyploidization with one Y chromosome and several X chromosomes.

Adult↗

A fluorescence in situ hybridization map of human chromosome 21 consisting of 30 genetic and physical markers on the chromosome: localization of 137 additional YAC and cosmid clones with respect to this map.

A fluorescence in situ hybridization (FISH) map of human chromosome 21 was compiled using yeast artificial chromosome (YAC) DNA probes that encode 28 markers physically and/or genetically mapped on the chromosome. Probes that recognize the centromere and rDNA repeat sequences in the p arm were also placed as reference markers on the FISH map. For each probe, the location of the fluorescence hybridization signal was measured on metaphase chromosomes with respect to fractional chromosome length (FL) from p-ter. The location of the markers was established with a standard error of +/- 1.9 Mb using from 9 to 63 FL measurements for each probe. The relative order and separation of the markers as determined by FISH are shown to correspond well to those of other maps of the chromosome. Fifty-one additional YAC and 86 cosmid clones were also localized by FISH with respect to the 30 markers on the chromosome. The cosmids, chosen at random from a flow-sorter chromosome 21 cosmid library, show some biases in chromosome distribution.

Chromosome Mapping↗

Allelic deletion mapping on chromosome 6q and X chromosome inactivation clonality patterns in cervical intraepithelial neoplasia and invasive carcinoma.

OBJECTIVE: Loss of heterozygosity (LOH) profiles and X chromosome inactivation patterns are analyzed in 42 patients with cervical intraepithelial neoplasias (CIN), including low-grade (CIN1) and high-grade (CIN2, CIN3) lesions, and 22 patients with invasive cervical carcinomas. METHOD: Laser capture microdissection was utilized to procure pure matched normal and lesional cells from each case. Sixteen microsatellite markers on four chromosomal arms, 6q21-q25.1, 8p21, 13q12.3--q13, and 17q12--q21, were amplified for LOH, as well as the HUMARA locus for X chromosome inactivation analysis. Eight additional markers spanning the long arm of chromosome 6 were utilized in all cases showing LOH on this arm and in which further tissue material was available for microdissection. RESULTS: Fifty-five percent of carcinomas showed deletions on chromosome bands 6q21--q25.1, 43% on 13q12.3--q13, and 40% on 17q12--q21. Deletions on 6q were identified in CIN3 (40%), CIN2 (37%), and CIN1 (10%), on 13q in CIN3 (33%) and CIN2 (33%), and rarely on chromosomal arm 17q. Finer 6q mapping revealed that marker D6S310 (q22) represented the centromeric and marker D6S255 (q25--q16) the telomeric boundary of deletion. A second, telomeric area of deletion at marker D6S281 (q27) was also identified. Monoclonal X chromosome inactivation patterns were identified in 12/13 cancers, 13/14 CIN3, 5/10 CIN2, and 0/6 CIN1. CONCLUSIONS: Two areas of deletion on chromosome 6q were identified in cervical tumors, suggesting the presence of tumor suppressor gene(s) inactivated in this neoplasia. LOH on this arm were identified early during cervical tumor progression. LOH on 13q and 17q also occur in cervical cancers. X chromosome inactivation patterns suggest that CIN develops into a monoclonal lesion during progression from CIN1 to CIN3.

Chromosome Mapping↗

Partner choice in heterologous chromosome segregation of the Y chromosome in competitive situations in the oocyte of Drosophila melanogaster.

Heterologous segregation of the Y chromosome and secondary non-disjunction of the X chromosomes in female meiosis of Drosophila melanogaster was investigated in ten different crosses where different constellations of translocation/inversion or translocation/translocation systems of the large autosomes were present in the female parent. It appeared that the Y chromosome always segregates from the shortest of the possible heterologous pairing partners. This may be due to size-dependent mechanism of so-called 'distributive disjunction' or to the possibility that the shorter the chromosome element is, the more easily it moves in the nucleus of the oocyte. Secondary non-disjunction of the X chromosomes appeared to be lower the more possible autosomal pairing partners the Y chromosome had, suggesting that the autosomes effectively compete with the X chromosomes for pairing with the Y chromosome. An alternative explanation is that, due to interchromosomal effect on recombination, crossing over in the X chromosomes was different in different experiments.

Animals↗

Sperm chromosome analysis in a man heterozygous for a paracentric inversion of chromosome 7 (q11q22).

Human sperm chromosomes were studied in a man heterozygous for a paracentric inversion of chromosome 7 (q11q22). The pronuclear chromosomes were analysed after in vitro penetration of golden hamster (Mesocricetus auratus) eggs. Ninety-four sperm chromosome spreads were examined, of which 34 contained the normal number 7 chromosome and 59 the inverted 7. This segregation was significantly different from the expected 1:1 ratio. The number of X- to Y-bearing sperm was 48 and 46 respectively. No sperm contained a recombinant chromosome caused by a crossover within the inversion. The frequency of chromosomal abnormalities in other chromosomes was 9.6%, which is not significantly different from the frequency observed in normal donors (8.9%) in our laboratory. These results suggest that the risk of chromosomally unbalanced sperm is not high for this paracentric inversion.

Animals↗

Stabilization of chromosomes by DNA intercalators for flow karyotyping and identification by banding of isolated chromosomes.

A number of structurally unrelated DNA intercalators have been studied as stabilizers of mitotic chromosomes during isolation from rodent and human metaphase cells. Seven out of the nine intercalators tested were found to be useful as chromosome stabilizing agents. Chromosome suspensions prepared in this way could be preserved for long periods of time. After isolation the chromosomal DNA was longer than 150 kb. With intercalated chromosomes high resolution flow karyotypes could be obtained as illustrated for the non-fluorescent intercalators 9-methylene-(1,3-dimethyl-2,4-dionepyrimidine-5-yl)-phenanthrid in iumchloride and 4'-aminomethyl-4,5', 8-trimethylpsoralen combined with DAPI and 33258 Hoeschst for fluorescent staining and for the fluorescent intercalator propidium iodide used as a stabilizer and as a fluorochrome. Passage of the intercalated chromosomes through the laser beam had no measurable effect on the length of the chromosomal DNA subsequently isolated. After flow analysis and collection on slides human chromosomes could easily be banded by Giemsa staining methods with the same resolution as obtained in conventional metaphase spreads. This allowed a ready identification of about 80 percent of all chromosomes in the unfractionated suspension collected after passage through the laser beam.

Animals↗

Direct analysis of radiation-induced chromosome fragments and rings in unstimulated human peripheral blood lymphocytes by means of the premature chromosome condensation technique.

Development of the procedure to stimulate peripheral blood lymphocytes has greatly facilitated the understanding of chromosome aberration formation and repair mechanisms in human cells. Yet, because radiation induces far more initial chromosome breaks than are observed as aberrations in metaphase, it has not been possible to examine the kinetics of primary chromosome breakage and rejoining with this procedure. An improved method to induce premature chromosome condensation in unstimulated lymphocytes has been used to study primary chromosome breakage, rejoining, and ring formation at various times after irradiation with up to 800 rad of X-rays. The dose-response relations for chromosome fragments analyzed immediately or 1, 2, or 24 h after exposure were found to be linear. Rapid rejoining of chromosome fragments, which takes place in the first 3 h after X-ray exposure, was not correlated with a simultaneous increase in the formation of rings. The yield of rings per cell scored 24 h after irradiation, however, increased significantly and fit a linear quadratic equation. Both chromosome fragment rejoining and ring formation were completed about 6 h after irradiation. The frequency distributions of rings among cells followed a Poisson distribution, whereas chromosome fragments were overdispersed.

Animals↗

Characterization of an analphoid, neocentromere-positive inv dup 8p marker chromosome using multiplex whole chromosome and sub-telomere FISH analyses.

A 30-year-old male patient with mild mental retardation was found to have a small supernumerary marker chromosome (SMC) in 90% of his peripheral blood cells and in 100% of his fibroblast cells. Multiplex whole chromosome and sub-telomere FISH analyses were used to determine that this SMC is an inverted duplicated distal chromosome 8p fragment. Although it was negative for alpha-DNA sequences, this marker had a functional kinetochore (neocentromere) demonstrated by a positive signal with a CENP-C antibody. Apparently intact 8p telomeres at the marker's ends were demonstrated by using a telomere repeat FISH probe. The patient's phenotypically normal mother on G-banding analysis had a small marker chromosome in 8% of her peripheral blood cells in two cultures of the first specimen studied. The marker was not seen in any subsequent maternal peripheral blood or fibroblast specimens. Although it was impossible to further characterize the maternal SMC, it was suggested that the mother had the same marker as the one seen in the proband. Inverted duplicated chromosomal fragments are the most frequent type of analphoid markers. Stable inverted duplicated 8p marker chromosomes were previously reported in three other patients. They all apparently occurred de novo and were found to be positive for kinetochore-associated proteins. Evidence for the possible inheritance of an inverted-duplicated, analphoid SMC was not shown to-date. This study also demonstrates a practical, straightforward approach for analphoid marker characterization in clinical laboratory settings, using whole chromosome multiplex and subtelomere-specific FISH analyses. FISH probes for all sub-telomere chromosomal regions are commercially available and the large majority of analphoid marker chromosomes involve telomere regions.

Adult↗

Chromosomal assignment of human genes for gastrin, thyrotropin (TSH)-beta subunit and C-erbB-2 by chromosome sorting combined with velocity sedimentation and Southern hybridization.

Human genes for gastrin, thyrotropin (THS)-beta subunit and c-erbB-2 were assigned to specific chromosomes using a single-laser cell sorter. For this purpose, condensed human chromosomes prepared from a karyotypically normal lymphoblastoid cell line were preliminarily fractionated by velocity sedimentation, and then sorted using a fluorescence-activated cell sorter. DNA was then extracted from the chromosomes, cleaved by restriction enzymes, and subjected to Southern hybridization using gene-specific radioactive probes. When the assignment of specific chromosomes was not possible due to chromosomal size overlapping, sorted chromosomes from cell lines carrying chromosomal translocation or from hybrid cells carrying known human chromosomes were used in addition. The results indicate that human genes for gastrin, TSH-beta, and c-erbB-2 are located on chromosomes 17, 1 and 17, respectively.

Cell Fractionation↗

Chromosomal abnormality and Y chromosome microdeletion in Chinese patients with azoospermia or severe oligozoospermia.

Chromosomal abnormality and Y chromosome microdeletion are regarded as two frequent genetic causes associated with spermatogenic failure in Caucasian population. To investigate the distribution of the two genetic defects in Chinese patients with azoospermia or severe oligozoospermia, karyotype analysis by G-banding was carried out in 358 idiopathic infertile men, including 256 patients with azoospermia and 102 patients with severe oligozoospermia, and screening of AZF region microdeletion of Y chromosome by multiplex PCR was performed in those patients without detectable chromosomal abnormality and 100 fertile controls. Of 358 patients, 39(10.9%) were found to have chromosomal abnormalities in which Klinefelter's syndrome (47, XXY) was the most common chromosomal aberration. The incidence of sex chromosomal abnormality in patients with azoospermia was significantly higher than that in patients with severe oligozoospermia (12.1% vs 1%). Among the rest of the 319 patients with normal karyotype, 46 (14.4%) were found to have microdeletions in AZF region. The prevalence rates of AZF microdeletion was 15% and 13.1% in patients with azoospermia and severe oligozoospermia respectively. The microdeletion in AZFc was the most frequent deletion and all the microdeletions in AZFa were found in azoospermic patients. No microdeletion in AZF region was detected in fertile controls. In conclusion, chromosomal abnormality and AZF region microdeletion of Y chromosome might account for about 25% of Chinese infertile patients with azoospermia or severe oligozoospermia, suggesting the two abnormalities are important genetic etiology of spermatogenic failure in Chinese population and it is essential to screen them during diagnosis of male infertility before in vitro assisted fertilization by introcytoplasmic sperm injection.

Adult↗

Telomere-telomere (end to end) fusion of chromosomes 7 and 22 with an interstitial deletion of chromosome 7p11.2-->p15.1: phenotypic consequences and possible mechanisms.

We report a rare case of a de novo end to end fusion of chromosomes 7 and 22 in conjunction with an interstitial deletion of chromosome 7p11.2p15.1 in a newborn with congenital anomalies. The proband presented for chromosome analysis with bilateral cataracts, dysmorphic facies and distal limb abnormalities. Chromosome analysis showed a 45,XY,der(22)psu dic(22;7)(p13;p22.3)del(7)(p11.2p15.1) karyotype. This short arm to short arm fusion of chromosomes 7 and 22 resulted in a pseudodicentric chromosome. The interstitial deletion in the short arm of chromosome 7 was likely a result of breakage and reunion related to instability of the dicentric chromosome. Loss of genetic material in this region of chromosome 7p has been implicated in the pathophysiology of craniosynostosis and cephalopolysyndactyly syndromes.

Abnormalities, Multiple↗

Carcinogen-specific targeting of chromosome 12 for loss of heterozygosity in mouse lung adenocarcinomas: implications for chromosome instability and tumor progression.

Genotoxic carcinogens exert their tumorigenic effects in part by inducing genomic instability. We recently showed that loss of heterozygosity (LOH) on chromosome 12 associates significantly with the induction of chromosome instability (CIN) by the likely human lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and vinyl carbamate (VC) during mouse lung carcinogenesis. Here, we demonstrate the carcinogen specificity of this event and its effect on lung tumor evolution. LOH on chromosome 12 was observed in 45% of NNK-induced, 59% of VC-induced, 58% of aflatoxin B1 (AFB1)-induced, 14% of N-ethyl-N-nitrosourea (ENU)-induced and 12% of spontaneous lung adenocarcinomas. The frequency of LOH in each of the carcinogen-induced groups, except ENU, was significantly higher than in the spontaneous group (P<0.001). Deletion mapping revealed four potential candidate regions of 1-4 centiMorgans suspected to contain targeted tumor suppressor genes, with at least one expected to have a role in CIN. The relationship between LOH on chromosome 12 and additional chromosomal alterations occurring during lung tumor progression was also examined. LOH on chromosomes 1 and 14 were moderately frequent during malignant progression in tumors from all treatment groups, occurring in 21-35 and 18-33% of tumors. However, these alterations showed significant concurrence with LOH on chromosome 12 in VC-, NNK- and AFB1-induced tumors (P<0.05). The results suggest that a carcinogen-selective mechanism of lung cancer induction involves the frequent inactivation of genes on chromosome 12, including a stability gene that evidently promotes the evolutionary selection of additional chromosomal alterations during malignant progression.

Adenocarcinoma↗

The mitotic chromosome is an assembly of rigid elastic axes organized by structural maintenance of chromosomes (SMC) proteins and surrounded by a soft chromatin envelope.

The structure of mitotic chromosomes is still poorly understood. Here we describe the use of a novel approach based on elasticity measurements of a single chromosome for studying the organization of these objects. The data reveal that mitotic chromosomes exhibit a non-homogenous structure consisting of rigid elastic axes surrounded by a soft chromatin envelope. The chemical continuity of DNA, but not RNA, was required for the maintenance of these axes. The axes show a modular structure, and the structural maintenance of chromosomes (SMC) proteins participate in their organization. Topoisomerase II was not involved in either the organization of the axes or the maintenance of the mitotic chromosomes. A model for the assembly and the structure of the mitotic chromosome is proposed. According this model, the chromosome axes are dynamic structures that assemble at the onset and disassemble the end of mitosis, respectively. The SMC proteins, in addition to maintaining axis elasticity, are essential for the determination of the rod-like chromosome shape. The extreme compaction of mitotic chromosomes is determined mainly by the high amount of bivalent ions bound to DNA at mitosis.

Animals↗

Genomewide search for type 2 diabetes-susceptibility genes in French whites: evidence for a novel susceptibility locus for early-onset diabetes on chromosome 3q27-qter and independent replication of a type 2-diabetes locus on chromosome 1q21-q24.

Despite recent advances in the molecular genetics of type 2 diabetes, the majority of susceptibility genes in humans remain to be identified. We therefore conducted a 10-cM genomewide search (401 microsatellite markers) for type 2 diabetes-related traits in 637 members of 143 French pedigrees ascertained through multiple diabetic siblings, to map such genes in the white population. Nonparametric two-point and multipoint linkage analyzes-using the MAPMAKER-SIBS (MLS) and MAXIMUM-BINOMIAL-LIKELIHOOD (MLB) programs for autosomal markers and the ASPEX program for chromosome X markers-were performed with six diabetic phenotypes: diabetes and diabetes or glucose intolerance (GI), as well as with each of the two phenotypes associated with normal body weight (body-mass index<27 kg/m(2)) or early age at diagnosis (<45 years). In a second step, high-resolution genetic mapping ( approximately 2 cM) was performed in regions on chromosomes 1 and 3 loci showing the strongest linkage to diabetic traits. We found evidence for linkage with diabetes or GI diagnosed at age <45 years in 92 affected sib pairs from 55 families at the D3S1580 locus on chromosome 3q27-qter using MAPMAKER-SIBS (MLS = 4.67, P=.000004), supported by the MLB statistic (MLB-LOD=3.43, P=.00003). We also found suggestive linkage between the lean diabetic status and markers APOA2-D1S484 (MLS = 3. 04, P=.00018; MLB-LOD=2.99, P=.00010) on chromosome 1q21-q24. Several other chromosomal regions showed indication of linkage with diabetic traits, including markers on chromosome 2p21-p16, 10q26, 20p, and 20q. These results (a) showed evidence for a novel susceptibility locus for type 2 diabetes in French whites on chromosome 3q27-qter and (b) confirmed the previously reported diabetes-susceptibility locus on chromosome 1q21-q24. Saturation on both chromosomes narrowed the regions of interest down to an interval of <7 cM.

Age of Onset↗