A Y/15 translocation in a 45,X male with Prader-Willi syndrome

We report a male neonate with a 45 X karyotype; the long arm of a chromosome 15 was translocated onto the proximal long arm of the Y chromosome. Breakpoints were identified by in situ fluorescence hybridization (FISH) on the proximal 15q13 and Yq11.2. The derivative chromosome has no primary centromere. Clinical features were compatible with Prader-Willi syndrome. This is the first report case ofmonosomy 15q and Yq deletion with Prader-Willi syndrome.     

A 45,X male with evidence of a translocation of Y euchromatin onto chromosome 15

Summary A 19-year-old male with azoospermia was found to have a 45,X karyotype with additional euchromatic material on 15p. The parents' karyotypes are normal. The cytogenetic data, the positive H-Y-typing, and the presence of Yp-specific restriction fragments detected in the proband's genome by molecular DNA probes suggest that the short arm of the Y chromosome, including part of the centromere, is translocated onto the nucleolus organizer region (NOR) of chromosome 15.     

De novo (11;13) translocation.

A male infant is described with unusual facial appearance, clubfeet, and moderate hydrocephalus internus without obvious deficiency in mental and physical development. Cytogenetic studies revealed a karyotype of 45,XY,--C,--D,+t(C;D). A chromosome 11 and a 13 are involved in the formation of the translocation chromosome. The long arm of chromosome 13 is linearly attached to the end of the long arm of chromosome 11 (tandem translocation). Chromosome material of the distal part of the long arm of chromosome 11, as well as the short arm plus the centromere of chromosome 13 seem to have been lost.     

A study of cryptic terminal chromosome rearrangements in recurrent miscarriage couples detects unsuspected acrocentric pericentromeric abnormalities

Fifty chromosomally normal couples with three or more miscarriages were examined using fluorescent in situ hybridisation (FISH) and a library of subtelomere-specific probes together with alphoid repeats mapping to the acrocentric centromeres. Six abnormalities were found. Firstly, a cryptic reciprocal subtelomere translocation between the long arm of a chromosome 3 and the short arm of a chromosome 10. The other five cryptic abnormalities involved the acrocentric chromosome pericentromeric regions and in one case also Yp. Two patients had a rearranged chromosome 13, where the centromeric region was found to be derived from the short arm, centromere and proximal long arm of chromosome 15. Another two patients had a derived chromosome 22, where the centromere was replaced by two other centromeres, one derived from chromosome 14 and the other from either chromosome 13 or 21, while one patient had the subtelomere region of Yp translocated onto the short arm of a chromosome 21. These abnormalities may be the underlying cause of the recurrent miscarriages, because they may result in abnormal pairing configurations at meiosis leading to non-disjunction of whole chromosomes at metaphase I. The frequency of rearrangements seen in the recurrent miscarriage patient population was significantly different from that in the control group ( P=0.0096, Fisher's exact test) due to the acrocentric pericentromeric abnormalities.     

Ring (15) chromosome

Summary Cytogenetic studies on lymphocytes from a girl aged 3 years and 10 months revealed a ring chromosome 15. Several banding methods showed the r(15) chromosome not to have any apparent deletion of the long arm. The silver staining technique for nucleolar organizer regions showed an NOR positive region (band p12). In only a few cells was a chromosome 15 missing. The size of the r(15) was found to be constant. Comparison with 11 previous reported cases in the literature shows that the clinical manifestations in the different patients with ring chromosome 15 are constant although not clinically identifiable and it appears likely to attribute them to a significantly retarded intrauterine and postnatal growth instead of presumed deficiency in the long arm and mosaic configurations.     

RFLP and physical mapping with an rDNA-specific endonuclease reveals that nucleolus organizer regions of Arabidopsis thaliana adjoin the telomeres on chromosomes 2 and 4

Ribosomal RNA genes are organized in tandem arrays called nucleolus organizer regions (NORs). In a prior study, RFLP mapping on pulsed-field gels placed NOR2 at the northern tip of Arabidopsis thaliana chromosome 2. New polymorphisms have allowed the other NOR, NOR4 , to be mapped to the northern tip of chromosome 4. To map NOR-associated loci, rDNA-specific cleavage by I- Ppo I, an endonuclease with a 15 nucleotide recognition sequence involved in rDNA-homing of a mobile, self-splicing Group I intron in Physarum was exploited. I- Ppo digestion of A. thaliana genomic DNA liberated two telomere-containing fragments no larger than 13 kbp, and telomere polymorphisms identified using I- Ppo I co-segregated with NOR2 and NOR4 . Restriction mapping suggested that telomere-proximal rRNA genes are oriented with their 5' ends nearest the chromosome ends and their 3' ends nearest the centromere. This orientation was confirmed using the polymerase chain reaction to clone one of the telomere—rDNA junctions, most likely the junction on chromosome 4. The telomeric repeats join the terminal rRNA gene downstream of its promoter, suggesting that this first gene is inactive. Subtelomeric repetitive DNAs are absent at the telomere—rDNA junction. Localization of NOR2 , NOR4 and their associated telomeres, TEL2N and TEL4N , respectively, provides end points for the genetic and physical maps of chromosomes 2 and 4.     

rDNA and acrocentric chromosomes in man

Summary A malformed female infant was found to have a 46,XX complement with a chromosome 8 shorter than normal with a secondary constriction and satellites on the short arm. Chromosome studies on the clinically normal father showed a balanced translocation between chromosome 8 and 13, i.e., 46,XY,t(8;13) (p21 p12). The proposita, carrier of the unbalanced form of the translocation, resulted partially monosomic for short arm of chromosome 8 (8p-) and partially trisomic for short arm of chromosome 13.The levels of DNA complementary to rRNA (normal in the father who had 10 NOR and increased in the proposita who had 11 NOR) confirmed our interpretation of the rearrangement.     

Trisomy 8p: unusual origin detected by fluorescence in situ hybridization

Summary Chromosomal analysis of a neonate with brain and heart abnormalities revealed trisomy for 8p. The mother's karyotype showed 47 chromosomes with one chromosome 8 being represented as two separate chromosomes, an acrocentric 8p and a telocentric 8q. Gbanding and silver staining revealed a satellite and nucleolus organizing region (NOR) on the 8p. Centromericspecific probes to the centromeres of chromosomes 8, 15, 13/21, 22 and the acrocentric chromosomes revealed that only the 8q centromere was of chromosome-8 origin, while the 8p centromere was of chromosome-14 origin.     

Molecular cytogenetic characterization of Thinopyrum intermedium-derived wheat germplasm specifying resistance to wheat streak mosaic virus

Thinopyrum intermedium is a promising source of resistance to wheat streak mosaic virus (WSMV), a devastating disease of wheat. Three wheat germplasm lines possessing resistance to WSMV, derived from Triticum aestivum×Th. intermedium crosses, are analyzed by C-banding and genomic in situ hybridization (GISH) to determine the amount and location of alien chromatin in the transfer lines. Line CI15092 was confirmed as a disomic substitution line in which wheat chromosome 4A was replaced by Th. intermedium chromosome 4Ai?2. The other two lines, CI17766 and A29-13-3, carry an identical Robertsonian translocation chromosome in which the complete short arm of chromosome 4Ai?2 was transferred to the long arm of wheat chromosome 4A. Fluorescence in situ hybridization (FISH) using ABD genomic DNA from wheat as a probe and S genomic DNA from Pseudoroegneria stipifolia as the blocker, and vice versa, revealed that the entire short arm of the translocation was derived from the short arm of chromosome 4Ai?2 and the breakpoint was located at the centromere. Chromosomal arm ratios (L/S) of 2.12 in CI17766 and 2.15 in A29-13-3 showed that the translocated chromosome is submetacentric. This translocated chromosome is designated as T4AL?? 4Ai?2S as suggested by Friebe et al. (1991).     

A Radiation Hybrid Map of 95 STSs Spanning Human Chromosome 13q

We have constructed a high-resolution physical map of the long arm of human chromosome 13 using a panel of 94 radiation hybrids. A comprehensive map of 95 chromosome 13-specific sequence tagged sites (STSs) spanning 13q from the presumed centromere at D13Z1 to the known telomere was obtained by multipoint maximum likelihood statistical methods. The 95 markers have an average retention frequency of 10%, with markers closer to the centromere having much greater retention frequencies (22-49%) than distal 13q markers (2-12%) The most likely radiation hybrid map localized the 95 STSs into 54 unique map positions, 34 with odds of 1000:1 or greater; the comprehensive map localized all but 17 STSs with odds exceeding 10:1. The total map length of 13q was 1302 cR₉₀₀₀ (range 6.4-94.4 cR₉₀₀₀) and a physical distance of 98 Mb, so that 1% breakage in the RH panel corresponds to 75 kb. A comparison of the comprehensive RH map to genetic maps of chromosome 13q shows identical locus orders for the common markers, with two exceptions over 1-cM distances. We discuss the possible relationships between the genetic and the radiation hybrid maps.     

Centromere function and nondisjunction are independent components of the maize B chromosome accumulation mechanism

Supernumerary or B chromosomes are selfish entities that maintain themselves in populations by accumulation mechanisms. The accumulation mechanism of the B chromosome of maize (Zea mays) involves nondisjunction at the second pollen mitosis, placing two copies of the B chromosome into one of the two sperm. The B chromosome long arm must be present in the same nucleus for the centromere to undergo nondisjunction. A centromere, containing all of the normal DNA elements, translocated from the B chromosome to the short arm of chromosome 9 was recently found to be epigenetically silenced for centromeric function. When intact B chromosomes were added to this genotype, thus supplying the long arm, the inactive centromere regained the property of nondisjunction causing the translocation chromosome 9 to be differentially distributed to the two sperm or resulted in chromosome breaks in 9S, occasionally producing new translocations. Translocation of the inactive B centromere to chromosome 7 transferred the nondisjunction property to this chromosome. The results provide insight into the molecular and evolutionary basis of this B chromosome accumulation mechanism by demonstrating that nondisjunction is caused by a process that does not depend on normal centromere function but that the region of the chromosome required for nondisjunction resides in the centromeric region.     

Mosaicism for an ectopic NOR at 8pter and a complex rearrangement of chromosome 8 in a patient with severe psychomotor retardation

We describe a 3-year-old girl with severe delays in mental and motor skills, a history of generalized seizures, and subtle dysmorphic features. Conventional cytogenetics revealed a mosaic karyotype. A de novo ectopic NOR at the telomeric region of the short arm of one chromosome 8 (8ps) was found in 90% of lymphocyte and in 98% of fibroblast metaphases. A small NOR-bearing marker chromosome and a large derivative chromosome 8 without short arm satellites (der(8)) were present in the remaining cells. FISH with a probe specific for centromeres 14 and 22 labeled both the telomeric region of 8ps and the small marker centromere. Der(8) included an inverted duplication of 8p and a rearranged duplication of 8q but lacked a second centromere. A subtelomeric probe for 8p revealed a cryptic deletion in 8ps and der(8). Thus, the karyotype represents a combination of submicroscopic partial monosomy 8pter and mosaic trisomy 8.     

Cytological identification of an isotetrasomic in rice and its application to centromere mapping

The aneuploid with isochromosome or telochromosome is ideal material for exploring the position of centromere in lingkage map.For obtaining these aneuploids in rice,the primary trisomics from triplo-1 to triplo-12 and the aneuploids derived from a triploid of indica rice variety Zhongxiao 3037 were carefully investigated.From the offsprings of triplo-10,a primary trisomic of chromosome 10 of the variety,an isotetrasomic “triplo-10-1” was obtained.Cytological investigation revealed that a pair of extra isochromosomes of triplo-10-1 were come from the short arm of chromosome 10.In the offsprings of the isotetrasomic,a secondary trisomic “triplo-10-2”,in which the extra-chromosome was an isochromosome derived from the short arm of chromosome 10,was identified.With the isotetrasomic,secondary trisomic,primary trisomic and diploid of variety Zhongxiao 3037,different molecular markers were used for exploring the position of the centromere of chromosome 10.Based on the DNA dosage effect,it was verified that the molecular markers G1125,G333 and L169 were Located on the short arm,G1084 and other 16 available molecular markers were on the long arm of chromosome 10.So the centromere of chromosome 10 was located somewhere between G1125 and G1084 according to the RFLP linkage map given by Kurata et al[1].The distance from G1125 to G1084 was about 3.2cM.     

Banding studies and synaptonemal complex analysis of an X-autosome translocation in the domestic pig

In a litter of nine domestic pigs, a translocation between the X-chromosome and chromosome 13 was found in six individuals: four males and two females. The translocation was presumed to have originated in the dam. Banding studies indicated that the breaks preceding the translocation had occurred in a distal GTG-negative band of the long arm of the X, 15-30% of the length of Xq from the telomere, and proximally in chromosome 13, 15-25% from the centromere. The normal X of the females invariably replicated its DNA late. Synaptonemal complex analysis of spermatocytes demonstrated a quadrivalent in 75 of 85 analyzable cells (88.2%), and in 10 cells (11.8%) one trivalent and one univalent were found. Extensive nonhomologous pairings were visualized in the pachytene stage by applying an 'overlap' test measuring the sex chromosomes and collating their pairings. An arrest in male meiosis was verified histologically; no meiotic stages later than pachytene developed. This resulted in sterility, with considerable testicular hypoplasia. The records of female fertility were available only for the dam and did not show any deviations from the average of the herd.     

A tdic(5;15)(p31;p11) chromosome showing variation for constriction in the centromeric regions in a patient with the cri du chat syndrome.

Some dicentric chromosomes show only one primary constriction at metaphase and behave in cell division as if they are monocentric. The few previous reports of tdic (translocation dicentric) chromosomes showing one morphologic indicate that among the cells of an individual the same centromere consistently shows the primary constriction. The present case deals with a tdic(5;15)(p13;p11) chromosome that is an exception to this pattern. Scoring 98 GTG-, C-, and QFQ-banded metaphases specifically for primary constrictions revealed 15 (15%) containing a tdic chromosome with a single primary constriction. Among these chromosomes, 8 (8%) were at the chromosome 15 centromere and 7 (7%) were at the chromosome 5 centromere. The remaining 83 (85%) tdic chromosomes showed two primary constrictions. We analyzed a total of 172 metaphases from peripheral blood, and all except 3 (1.7%) contained the tdic chromosome. Among these three cells, the tdic chromosome was broken in two and absent in one, which indicates that there was some unstable separation of this dicentric in cell division. In two metaphases, there was a chromatid gap at the site of one centromere. Possibly, the absence of certain primary constrictions was associated with deletion of centromeres. This mechanism may be a continual source for additional centromere inactivation during the life of this patient. This case demonstrates that for some dicentrics either centromere may become nonfunctional and inactivation can occur more than once within an individual. The karyotype of this patient was 45,XX,tdic(5;15)(p31;p11). Thus, she was monosomic for about 3/4 of the chromosome 5 short arm. Clinically, this infant had a shrill catlike cry and facies of the cri du chat syndrome.     

Physical mapping of three fruit ripening genes：Endopolygalacturonase,ACC oxidase and ACC synthase from apple（Malus x domestica） in an apple rootstock A106（Malus sieboldii

The apple rootstock,A106(Malus sieboldii),had 17 bivalents in pollen mother cells at meiotic metaphase 1,and 17 chromosomes in a haploid pollen cell.Karyotypes were prepared from root-tip cells with 2n=34 chromosomes,Seven out of 82 karyotypes(8.5%) showed one pari of satellites at the end of the short arm of chromosome 3.C-bands were shown on 6 pairs of chromosomes 2,4,6,8,14,and 16 near the telomeric regions of short arms.Probes for three ripening-related genes from Malus x domestica:endopolygalacturonase(EPG,0.6kb),ACC oxidase(1.2kb),and ACC synthase(2kb)were hybridized in situ to metaphase chromosomes of A106.Hybridization sites for the EPG gene were observed on the long arm of chromosome 14 in 15 out of 16 replicate spreads and proximal to the centromere of chromosomes 6 and 11.For the ACC oxidase gene,hylridization sites were observed in the telomeric region of the short arm of chromosomes 5 and 11 in 87% and 81% of 16 spreads respectively,proxiaml to the centromere of chromosome 1 in 81% of the spreads,and on the long arm of chromosome 13 in 50% of the spreads. Physical mapping of three fruit ripening genes in an apple rootstock A106.Twenty five spreads were studied for the ACC synthase gene and hybridization sites were observed in the telomeric region of the short arm of chromosome 12 in 96% of the spreads.chromosomes 9 and 10 in 76% of the spreads,and chromosome 17 in 56% of the spreads.     

A hemicentric inversion in the maize line knobless Tama flint created two sites of centromeric elements and moved the kinetochore-forming region

A maize line, knobless Tama flint (KTF), was found to contain a version of chromosome 8 with two spatially distinct regions of centromeric elements, one at the original genetic position and the other at a novel location on the long arm. The new site of centromeric elements functions as the kinetochore-forming region resulting in a change of arm length ratio. Examination of fluorescence in situ hybridization markers on chromosome 8 revealed an inversion between the two centromere sites relative to standard maize lines, indicating that this chromosome 8 resulted from a hemicentric inversion with one breakpoint approximately 20 centi-McClintocks (cMc) on the long arm (20% of the total arm length from the centromere) and the other in the original cluster of centromere repeats. This inversion moved the kinetochore-forming region but left the remainder of the centromere repeats. In a hybrid between a standard line (Mo17) and KTF, both chromosome 8 homologues were completely synapsed at pachytene despite the inversion. Although the homologous centromeres were not paired, they were always correctly oriented at anaphase and migrated to opposite poles. Additionally, recombination on 8L was severely repressed in the hybrid.     

Cytogenetic and in situ DNA-hybridization studies in intracranial tumors of a patient with central neurofibromatosis

Summary We have studied a meningioma and an acoustic neurinoma of a patient with central neurofibromatosis. In the meningioma cells, one chromosome 22 was replaced by an almost metacentric, bisatellited marker chromosome that appeared monocentric after CBG-staining. In situ hybridization with a chromosome 22 centromere specific DNA probe (p22hom48.4) revealed specific signals in the pericentromeric region of the marker chromosome, indicating the presence of at least the short arm and the centromere of chromosome 22. The pericentromeric localization of the hybridization signals suggests the marker consists of an isoformation of the short arm of chromosome 22, resulting in a monosomy for the long arm of chromosome 22. In contrast to these finding in meningioma cells, no chromosomal abnormality could be detected in acoustic neurinoma cells. Our finding provide further evidence that loss of genetic material on the long arm of chromosome 22 is associated with the development of central neurofibromatosis.     

A molecular cytogenetic map of sorghum chromosome 1. Fluorescence in situ hybridization analysis with mapped bacterial artificial chromosomes

We used structural genomic resources for Sorghum bicolor (L.) Moench to target and develop multiple molecular cytogenetic probes that would provide extensive coverage for a specific chromosome of sorghum. Bacterial artificial chromosome (BAC) clones containing molecular markers mapped across sorghum linkage group A were labeled as probes for fluorescence in situ hybridization (FISH). Signals from single-, dual-, and multiprobe BAC-FISH to spreads of mitotic chromosomes and pachytene bivalents were associated with the largest sorghum chromosome, which bears the nucleolus organizing region (NOR). The order of individual BAC-FISH loci along the chromosome was fully concordant to that of marker loci along the linkage map. In addition, the order of several tightly linked molecular markers was clarified by FISH analysis. The FISH results indicate that markers from the linkage map positions 0.0-81.8 cM reside in the short arm of chromosome 1 whereas markers from 81.8-242.9 cM are located in the long arm of chromosome 1. The centromere and NOR were located in a large heterochromatic region that spans approximately 60% of chromosome 1. In contrast, this region represents only 0.7% of the total genetic map distance of this chromosome. Variation in recombination frequency among euchromatic chromosomal regions also was apparent. The integrated data underscore the value of cytological data, because minor errors and uncertainties in linkage maps can involve huge physical regions. The successful development of multiprobe FISH cocktails suggests that it is feasible to develop chromosome-specific "paints" from genomic resources rather than flow sorting or microdissection and that when applied to pachytene chromatin, such cocktails provide an especially powerful framework for mapping. Such a molecular cytogenetic infrastructure would be inherently cross-linked with other genomic tools and thereby establish a cytogenomics system with extensive utility in development and application of genomic resources, cloning, transgene localization, development of plant "chromonomics," germplasm introgression, and marker-assisted breeding. In combination with previously reported work, the results indicate that a sorghum cytogenomics system would be partially applicable to other gramineous genera.     

利用高灵敏的TSA-FISH在玉米中定位bz1、bz2基因(英文)

植物中 ,程序性细胞死亡 (PCD)发生在植物生殖和发育的许多方面 ,已有的研究表明 ,在玉米种子的发育过程中 ,胚乳组织经历了程序性细胞死亡的过程。bz1 (bronze)和bz2是与种子的糊粉层发育相关的花青素生物合成基因 ,在玉米基因组中 ,bz1基因所在区域是重组热点 ,bz2与类黄酮的酰化、糖基化、转运、沉积等有关 ,基因的物理定位有利于基因的分离和克隆。TSA FISH (Tyramidesignalamplificationfluorescenceinsituhybridization)是一种新颖的高灵敏度的荧光原位杂交技术 ,它的主要反应原理是辣根过氧化物酶催化过氧化氢和标记的酪胺分子 (tyramide)的苯环部分反应 ,使荧光标记的酪胺分子在直接带有或间接带有HRP报告分子的探针周围沉积 ,信号因此得以极大的放大 ,从而大大提高了荧光原位杂交技术的灵敏度 ,90年代中期开始引入动物和人类组织化学和细胞遗传学研究中 ,2 0 0 1年才应用于植物细胞遗传学的研究。利用这一技术 ,我们将bz1基因定位于玉米的第 9染色体的短臂和第 1染色体的长臂上 ,其信号点距着丝粒的百分距离分别为 40 .2 ,75 .4;bz2基因定位于玉米的第 1染色体的长臂和第 5染色体的短臂上 ,其信号点距着丝粒的百分距离分别为2 1 .6,1 5 .3。本文讨论了TSA FISH技术在植物中小的、低拷贝的DNA序