A Novel Interspersed Type of Organization of Satellite DNAs in Tribolium Madens Heterochromatin

Analysis of arrangement of satellite DNA sequences in Tribolium madens (Insecta, Coleoptera) by Southern analysis of pulsed-field blots and two colour FISH on extended chromosomes and DNA fibres revealed a novel type of heterochromatin organization. Two satellite DNAs, distributed over the whole pericentromeric heterochromatin of all chromosomes form clusters, ranging in size from 150 kb up to several Mb. Within the clusters, both satellites are in the form of highly interspersed, short homogeneous arrays which vary in size with a lowest length limit of only few kb. The longest arrays composed of a single satellite are relatively short, up to 70 kb for satellite I, and up to 45 kb for satellite II. Only a small fraction of about 15% of satellite II is organized in long tandem repeats, while the rest is in the form of only a few repeats intermingled with satellite I. The results indicate that large clusters composed of interspersed arrays of both satellites represent a major component of T. madens heterochromatin, which is mostly devoid of long regions of other sequences. The same organizational pattern probably also includes a region of the functional centromere. We propose that such an organizational pattern of DNA sequences in heterochromatin might be common in genomes characterized by a high rate of interchromosomal exchange. This pattern of organization is different from that in other animal as well as plant species analysed up to now, in which every satellite in heterochromatin is organized in a small number of large separate domains. This revised version was published online in August 2006 with corrections to the Cover Date.     

Incontinentia pigmenti: XXY male with a family history

We report on the case of a male who from the start of life displayed vesicular lesions; on the trunk these were clustered and on the limbs they adopted a linear configuration. After biopsy of one such lesion, the histopathological study was compatible with a diagnosis of incontinentia pigmenti (IP). In the following months, hyperkeratotic lesions appeared which later became pigmented. The mother and other female members of the family also showed different degrees of alteration related to the same disease. The karyotype study showed the existence of 47,XXY (Klinefelter syndrome). The exceptional nature of this case is that although it is the third case reported in the literature of a male affected by incontinentia pigmenti with a previous family history, it is the only one combining this characteristic with the presence of a 47,XXY karyotype.     

系列染色法分析人－（人－鼠）杂交瘤C8的染色体

Ｃ８杂交瘤分泌人的ＩｇＭ（λ）单克隆抗体，是具有肾综合征出血热病毒抗原内影像作用的Ａｂ２（β）我们用常规Ｇｉｅｍｓａ染色、Ｇ－分带和Ｃ－分带的系列染色法对Ｃ８杂交瘤细胞的染色体进行分析，发现除了小鼠染色体外，还含有人的１，２，５，７，９，１２，１６，１７，１８，１９，２０，２１和２２号染色体及大量标记染色体，人染色体中以较短的染色体出现频率较高。用系列染色法分析人－鼠杂交瘤中的染色体比单独用Ｇ分带法更易得到可靠的结论。     

Two-phase short-term culture method for cytogenetic investigations from human prostate carcinoma

An improved technique for primary short-term culture of prostate carcinoma cells in two phases, with and without serum, for subsequent cytogenetic analysis is reported and compared with four other methods. After mechanical disaggregation and a brief collagenase treatment of tumor specimens, cell clusters were seeded in RPMI 1640 and 15% fetal calf serum (FCS) without any other supplement in the first phase. The culture medium was changed to a serum-free medium supplemented with bovine pituitiary extract (BPE) and epidermal growth factor (EGF) when the first outgrowth became apparent. During this second phase, fibroblast growth could be virtually abolished within 48 hr. The epithelial and prostatic origin of the cultured cells was confirmed by immunocytochemical methods in each culture. Metaphase analysis revealed chromosome aberrations in over 80% of cases (both clonal and nonclonal alterations) indicating the presence of neoplastic cells. Clonal numerical chromosome aberrations, found by conventional cytogenetic analysis, were used to provide the reliability of the culture system in interphase nuclei of corresponding uncultured tumor tissue by fluorescence in situ hybridization (FISH). The main points of the described method are: 1) combined mechanical/enzymatic disaggregation, 2) seeding of the disaggregated cell clumps rather than of single cells, 3) initialization of the cultures in RPMI 1640 medium with 18% FCS without any other supplements, and (4) stimulating of selective epithelial proliferation by changing the culture conditions through serum-free medium. © 1994 Wiley-Liss, Inc.     

Molecular genetic studies of natives on Easter Island: evidence of an early European and Amerindian contribution to the Polynesian gene pool

Most archaeological and linguistic evidence suggest a Polynesian origin of the population of Easter Island (Rapanui), and this view has been supported by the identification of Polynesian mitochondrial DNA (mtDNA) polymorphisms in prehistoric skeletal remains. However, some evidence of an early South American contact also exists (the sweet potato, bottle gourd etc.), but genetic studies have so far failed to show an early Amerindian contribution to the gene pool on Easter Island. To address this issue, we analyzed mtDNA and Y chromosome markers and performed high-resolution human leukocyte antigen (HLA) genotyping of DNA harvested from previously collected sera of 48 reputedly nonadmixed native Easter Islanders. All individuals carried mtDNA types and HLA alleles previously found in Polynesia, and most men carried Y chromosome markers of Polynesian origin, providing further evidence of a Polynesian origin of the population of Easter Island. A few individuals carried HLA alleles and/or Y chromosome markers of European origin. More interestingly, some individuals carried the HLA alleles A*0212 and B*3905, which are of typical Amerindian origin. The genealogy of some of the individuals carrying these non-Polynesian HLA alleles and their haplotypic backgrounds suggest an introduction into Easter Island in the early 1800s, or earlier. Thus, there may have been an early European and Amerindian contribution to the Polynesian gene pool of Easter Island.     

Pallister-Killian syndrome: tetrasomy of 12pter-->12p11.22 in a boy with an analphoid, inverted duplicated marker chromosome

Supernumerary marker chromosomes (SMCs) without detectable alphoid DNA are predicted to have a neocentromere and have been referred to as mitotically stable neocentromere marker chromosomes (NMCs). Here we report the molecular cytogenetic characterization of a new case of Pallister-Killian syndrome (PKS) in a boy with an analphoid, inverted duplicated NMC derived from 12pter-->12p11.22 in his fibroblasts by using high-resolution comparative genetic hybridization (HR-CGH), multiplex fluorescent in situ hybridization (FISH) and bacterial artificial chromosome (BAC)-FISH mapping analyses with various alpha-satellite DNA probes, subtelomere probes and BAC-DNA probes. Precise identification of SMCs and NMCs is of essential importance in genetic counseling. HR-CGH is a more informative and often a faster way of precisely identifying the origin of SMCs. This case is the third report of PKS with an NMC containing an inverted duplication of partial 12p with available clinical data. These observations may help to determine the critical region for PKS and the mechanisms leading to the origin of the NMC derived from 12pter-->12p11.22 - a region that appears to be susceptible to the formation of neocentromeres. The use of subtelomeric probe PCP12p in buccal cells appears superior to the use of the centromere probe D12Z3 for the diagnosis of the PKS.     

Identification of origin of unknown derivative chromosomes by array-based comparative genomic hybridization using pre- and postnatal clinical samples

Microarray-based comparative genomic hybridization (array CGH) is a high-resolution and comprehensive method for detecting both genome-wide and chromosome-specific copy-number imbalance. We have developed an array CGH analysis system (consisting of an array CGH chip plus its exclusive analysis software) for constitutional genetic diagnosis and have evaluated the suitability of our system for molecular diagnosis using pre- and postnatal clinical samples. In a blind study, each of the 264 sample karyotypes identified by array CGH analysis was consistent with that identified by traditional karyotype analysis – with one exception, case (47, XXX) – and we were able to identify origins, such as small supernumerary marker chromosomes, which cannot be determined by conventional cytogenetics. We also acquired very accurate, fast and reliable results using a diminutive amount of clinical samples. Taken together, the array CGH platform developed in this study is a rapid, powerful and sensitive technology for pre- and postnatal diagnosis using a very small amount of clinical sample. J. Choe, J.-K. Kang, C.-J. Bae and D.-S. Lee contributed equally to this work.     

Analysis of isodicentric Ph chromosomes in chronic myeloid leukemia blast crisis北大核心CSCD

Objective To explore the genetic and clinical characteristics of isodicentric Ph chromosomes [idic(Ph)] in lymphoid blast crisis of chronic myeloid leukemia (CML-BLC). Methods Bone marrow aspirates of 2 patients withCML-BLC were analyzed by R banding after 24 hours of culturing. Genomic copy number variations (CNV) wereanalyzed by single nucleotide polymorphism array (SNP array) in case 1. The results were confirmed withfluorescence in situ hybridization (FISH). Variations of acute lymphoblastic leukemia-related genes includingCDKN2A/AB and PAX5 were detected by multiplex ligation-dependent probe amplication (MLPA). Results Deletionsand duplications on derivative chromosome 9 detected by FISH were confirmed by SNP array analysis. Thedistances between the BCR/ ABL fusion signals on the idic(Ph) chromosomes in the two patients have differedgreatly. The idic(Ph) in the second patient was supposed to be formed by two Ph chromosomes joined at their qterminals, where as the idic(Ph) in the first patient have been shown to be fused at the satellite regions oftheir p arms. Conclusion The idic(Ph) chromosomes presented in CML-BLC may predict resistance to Imatinib andresponse to Dasatinib.     

Constitutive ERK1/2 activation contributes to production of double minute chromosomes in tumour cells

Double minute chromosomes (DMs) are extrachromosomal cytogenetic structures found in tumour cells. As hallmarks of gene amplification, DMs often carry oncogenes and drug‐resistance genes and play important roles in malignant tumour progression and drug resistance. The mitogen‐activated protein kinase (MAPK) signalling pathway is frequently dysregulated in human malignant tumours, which induces genomic instability, but it remains unclear whether a close relationship exists between MAPK signalling and DMs. In the present study, we focused on three major components of MAPK signalling, ERK1/2, JNK1/2/3 and p38, to investigate the relationship between MAPK and DM production in tumour cells. We found that the constitutive phosphorylation of ERK1/2, but not JNK1/2/3 and p38, was closely associated with DMs in tumour cells. Inhibition of ERK1/2 activation in DM‐containing and ERK1/2 constitutively phosphorylated tumour cells was able to markedly decrease the number of DMs, as well as the degree of amplification and expression of DM‐carried genes. The mechanism was found to be an increasing tendency of DM DNA to break, become enveloped into micronuclei (MNs) and excluded from the tumour cells during the S/G₂ phases of the cell cycle, events that accompanied the reversion of malignant behaviour. Our study reveals a linkage between ERK1/2 activation and DM stability in tumour cells. © 2014 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Cytogenetic study of 105 children with acute lymphoblastic leukemia

Cytogenetic analysis was performed on 105 children with acute lymphoblastic leukemia (ALL). Adequate mitoses for study were obtained in 79 of the cases (71%). A normal karyotype was found in 18 patients (23%), while clonal chromosomal abnormalities were detected in 61 patients (77%). The karyotypes fell into five categories according to modal number: normal (18 patients), pseudodiploid (27 patients), hypodiploid (3 patients), hyperdiploid with 47-50 chromosomes (11 patients), and hyperdiploid with greater than or equal to 51 chromosomes (20 patients). Structural chromosome changes were found in 50 patients (63%); translocations were encountered in 15 of these patients (19%). The chromosome most often participating in translocations was number 19. Modal number was found to be an independent prognostic factor. Modal numbers 47-50 were associated with the poorest prognosis. The hyperdiploid clone with more than 50 chromosomes and the normal karyotype had the best prognosis.