Meiotic confirmation of the identification of chromosomes 9 and 13 in T(9; 19)163H,T(5; 13)264 Ca,and T(1; 13)70H stocks in Mus musculus

Quinacrine fluorescent banding patterns of chromosomes 9 and 13 are very similar in mitotic preparations of Mus musculus. Meiotic studies were carried out in male and female mice heterozygous for two translocations involving these chromosomes to determine whether the translocations have a common chromosome. The results indicate that chromosome 9 is involved in the T163H translocation but not in either the T70H or T264Ca translocations. The T70H and T264Ca translocations, but not the T163H, have chromosome 13 in common. These results support the interpretations based on mitotic studies.     

Mass Production of Intergeneric Chromosomal Translocations through Pollen Irradiation of Triticum durum-Haynaldia villosa Amphiploid

Haynaldia villosa possesses a lot of important agronomic traits and has been a powerful gene resource for wheat improvement. However, only several wheat-H, villosa translocation lines have been reported so far. In this study, we attempted to develop an efficient method for inducing wheat-H, villosa chromosomal translocations. Triticum durum- Haynaldia villosa amphiploid pollen treated with 1 200 rad ^60Co-y-rays was pollinated to Triticum aestivum cv. ＇Chinese Spring＇. Ninety-eight intergeneric translocated chromosomes between T. durum and H. villosa were detected by genomic in situ hybridization in 44 of 61 M1 plants, indicating a translocation occurrence frequency of 72.1%; much higher than ever reported. There were 26, 62 and 10 translocated chromosomes involving whole arm translocations, terminal translocations, and intercarlary translocations, respectively. Of the total 108 breakage-fusion events, 79 involved interstitial regions and 29 involved centric regions. The ratio of small segment terminal translocations （W.W-V） was much higher than that of large segment terminal translocations （W-V.V）. All of the M1 plants were self-sterile, and their backcross progeny was all obtained with ＇Chinese Spring＇ as pollen donors. Transmission analysis showed that most of the translocations were transmittable. This study provides a new strategy for rapid mass production of wheat-alien chromosomal translocations, especially terminal translocations that will be more significant for wheat improvement.     

Trigenomic chromosomes by recombination of <Emphasis Type="Italic">Thinopyrum intermedium </Emphasis>and <Emphasis Type="Italic">Th. ponticum </Emphasis>translocations in wheat

Rusts and barley yellow dwarf virus (BYDV) are among the main diseases affecting wheat production world wide for which wild relatives have been the source of a number of translocations carrying resistance genes. Nevertheless, along with desirable traits, alien translocations often carry deleterious genes. We have generated recombinants in a bread wheat background between two alien translocations: TC5, ex-Thinopyrum (Th) intermedium, carrying BYDV resistance gene Bdv2; and T4m, ex-Th. ponticum, carrying rust resistance genes Lr19 and Sr25. Because both these translocations are on the wheat chromosome arm 7DL, homoeologous recombination was attempted in the double hemizygote (TC5/T4m) in a background homozygous for the ph1b mutation. The identification of recombinants was facilitated by the use of newly developed molecular markers for each of the alien genomes represented in the two translocations and by studying derived F₂, F₃ and doubled haploid populations. The occurrence of recombination was confirmed with molecular markers and bioassays on families of testcrosses between putative recombinants and bread wheat, and in F₂ populations derived from the testcrosses. As a consequence it has been possible to derive a genetic map of markers and resistance genes on these previously fixed alien linkage blocks. We have obtained fertile progeny carrying new tri-genomic recombinant chromosomes. Furthermore we have demonstrated that some of the recombinants carried resistance genes Lr19 and Bdv2 yet lacked the self-elimination trait associated with shortened T4 segments. We have also shown that the recombinant translocations are fixed and stable once removed from the influence of the ph1b. The molecular markers developed in this study will facilitate selection of individuals carrying recombinant Th. intermedium–Th. ponticum translocations (Pontin series) in breeding programs. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A strategy for generation and balancing of autosome: Y chromosome translocations

We describe a method for generation and maintenance of translocations that move large autosomal segments onto the Y chromosome. Using this strategy we produced (2;Y) translocations that relocate between 1.5 and 4.8 Mb of the 2^nd chromosome.. All translocations were easily balanced over a male-specific lethal 1 (msl-1) mutant chromosome. Both halves of the translocation carry visible markers, as well as P-element ends that enable molecular confirmation. Halves of these translocations can be separated to produce offspring with duplications and with lethal second chromosome deficiencies . Such large deficiencies are otherwise tedious to generate and maintain.     

Cytogenetically balanced translocations are associated with focal copy number alterations

Current cytogenetic methods (e.g., G-banding and multicolor chromosomal painting) allow detection of translocation events but lack the resolution to (a) locate the breakpoints precisely at the chromosome band level or (b) discriminate balanced translocations from translocations with copy number alterations not previously reported, or imperfectly balanced translocations. In this study, we demonstrate that cytogenetically balanced translocations are in fact frequently associated with segmental gain or loss of DNA. The recent development of a whole genome tiling path BAC array has enabled tiling resolution analysis of genomic segmental copy number status. Combining tiling resolution BAC array comparative genomic hybridization (array CGH) with G-Banding analysis and multicolor chromosomal painting approaches such as spectral karyotyping (SKY) facilitates high-resolution mapping of genomic alterations associated with imperfectly balanced translocations. Using a refined version of our CGH array we have deduced the copy number status throughout the genomes of three cytogenetically well-characterized prostate cancer cell lines (PC3, DU145, LNCaP) to determine whether translocations are associated with focal gains and losses of DNA. At 78 kb tiling resolution we identified the boundaries of 170, 80, and 34 known and novel copy number alterations (CNA) in these cell line genomes, respectively. Thirty-three of the 36 known translocations (92%, P < 0.001) in DU145 were associated with segmental CNA. Likewise, 80% (P < 0.001) of the known translocations showed association in LNCaP. Although many translocation breakpoints exhibit segmental alteration in PC3, the pattern of chromosomal rearrangements is too complex for use in comprehensive association with CNA boundaries. Our results reveal that imperfectly balanced translocations in tumor genomes are a phenomenon that occurs at frequencies much higher than previously demonstrated. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Centromere structure and function analysis in wheat–rye translocation lines

1RS.1BL translocations are centric translocations formed by misdivision and have been used extensively in wheat breeding. However, the role that the centromere plays in the formation of 1RS.1BL translocations is still unclear. Fluorescence in situ hybridization (FISH) was applied to detect the fine structures of the centromeres in 130 1RS.1BL translocation cultivars. Immuno‐FISH, chromatin immunoprecipitation (ChIP)‐qPCR and RT‐PCR were used to investigate the functions of the hybrid centromeres in 1RS.1BL translocations. New 1R translocations with different centromere structures were created by misdivision and pollen irradiation to elucidate the role that the centromere plays in the formation of 1RS.1BL translocations. We found that all of the 1RS.1BL translocations detected contained hybrid centromeres and that wheat‐derived CENH3 bound to both the wheat and rye centromeres in the 1RS.1BL translocation chromosomes. Moreover, a rye centromere‐specific retrotransposon was actively transcribed in 1RS.1BL translocations. The frequencies of new 1RS hybrid centromere translocations and group‐1 chromosome translocations were higher during 1R misdivision. Our study demonstrates the hybrid nature of the centromere in 1RS.1BL translocations. New 1R translocations with different centromere structures were created to help understand the fusion centromere used for wheat breeding and for use as breeding material for the improvement of wheat.     

A method for accurate detection of translocation junctions in ewing family of tumors

The Ewing family of tumors (ET) generally contain translocations involving the EWS gene and the FLI or ERG genes. Identification of the translocation confirms the diagnosis of ET. Currently, diagnosis of the translocation is made by several methods. In general, these methods require different primer sets for amplifying different translocations and subsequent efforts to identify the amplified product. The need to employ different sets of primers to amplify different translocation junctions presents some limitations. We have developed a method based on PCR with consensus primers followed by direct automated sequencing of the amplified product. With this method we have correctly determined known as well as unknown ET-associated EWS-FLI and EWS-ERG translocations in appropriate specimens. Use of our consensus primers eliminates the need for separate PCRs to amplify EWS-FLI and EWS-ERG translocation junctions, and because direct sequencing is used for confirming the identity of the amplification product, the accuracy of detection becomes 100%. The method might also accurately diagnose ET-associated translocations other than EWS-FLI and EWS-ERG translocations.     

Genetic sexing of Anopheles stephensi with the larval morphological mutant Bl

The development of two genetic sexing systems for Anopheles stephensi based on the visible mutant black larvae (Bl) are reported. Two Y-linked translocations, T(Y-3)20 and T(Y-3)24, induced by 5 Krads X-ray irradiation were found to have breakpoints almost completely linked to Bl, showing recombination frequencies of less than 0.05% and 0.9% respectively. These strains can be maintained as stable inbreeding populations in which males are easily selected at the late 3rd or 4th larval instar by their half-black appearance, which is distinct from the full black phenotype of the females.A third Y-linked translocation, T(Y-3)9, in which the breakpoint showed only 0.7% recombination with an adult morphological mutant, short palpi (sp) was also isolated. Linkage between the breakpoint of 5 Y-linked translocations and the DDT resistance gene locus (DDT) was established providing incentive for further studies. Only two translocations showing poor linkage between the breakpoint and the dieldrin resistance gene locus (Dl) were identified. Linkage data and cytology indicated that each of the Y-chromosone 3 translocations studied involved the 3R arm, and not 3L where Dl is located.     

Viability of X-autosome translocations in mammals: an epigenomic hypothesis from a rodent case-study

X-autosome translocations are highly deleterious chromosomal rearrangements due to meiotic disruption, the effects of X-inactivation on the autosome, and the necessity of maintaining different replication timing patterns between the two segments. In spite of this, X-autosome translocations are not uncommon. We here focus on the genus Taterillus (Rodentia, Gerbillinae) which provides two sister lineages differing by two autosome–gonosome translocations. Despite the recent and dramatic chromosomal repatterning characterising these lineages, the X-autosome translocated species all display intercalary heterochromatic blocks (IHBs) between the autosomal and the ancestral sexual segments. These blocks, composed of highly amplified telomeric repeats and rDNA clusters, are not observed on the chromosomes of the non-translocated species, nor the Y1 and Y2 of the translocated species. Such IHBs are found in all mammals documented for X-autosome translocation. We propose an epigenomic hypothesis which explains the viability of X-autosome translocations in mammals. This posits that constitutive heterochromatin is probably selected for in X-autosome translocations since it may (1) prevent facultative heterochromatinization of the inactivated X from spreading to the autosomal part, and (2) allow for the independent regulation of replication timing of the sex and autosomal segments.     

Test of a possible correlation between cross-linking and chromosome breaking abilities of chemical mutagens

Summary The frequencies of sex-linked lethals and translocations were measured in the progeny ofDrosophila injected with either ethylene oxide or diepoxybutane. The ratio of translocations to lethals was the same after either type of treatment. This lends no support to the idea that the difference in carcinostatic activity between monofunctional and polyfunctional alklating agents is due to the cross-linking action of the latter type of compound on the chromosomes. Diepoxybutane did, in fact, inducefewer translocations than expected on the square dose-effect law for large rearrangements. Possible causes for this finding are discussed.With 1 Figure in the Text     

Automated brightfield break-apart in situ hybridization (ba-ISH) application: ALK and MALT1 genes as models

Cancer diagnosis can be a complex process, which takes consideration of histopathological, clinical, immunophenotypic, and genetic features. Since non-random chromosomal translocations are specifically involved in the development of various cancers, the detection of these gene aberrations becomes increasingly important. In recent years, break-apart (or split-signal) fluorescence in situ hybridization (FISH) has emerged as an advantageous technique to detect gene translocations on tissue sections. However, FISH assays are technically challenging and require specialized fluorescence microscopes. Furthermore, the FISH signal is not stable for long term archiving due to photo bleaching. Our objective was to demonstrate the feasibility of brightfield break-apart in situ hybridization (ba-ISH) for anaplastic lymphoma kinase (ALK) and mucosa-associated lymphoid tissue translocation protein 1 (MALT1) genes as models. ALK or MALT1 break-apart probes were labeled with digoxigenin (DIG) or 2,4-dinitrophenyl (DNP) on both sides of a known gene breakpoint region and the hybridization sites were visualized with the combination of alkaline phosphatase (AP)-based blue and red detection. Therefore, normal genes are detected as purple dots by mixing blue and red colors while translocated genes are detected as isolated blue or red dots. Formalin-fixed, paraffin-embedded tonsil was used as control for the co-localized 5′ and 3′ probes. Gene translocations of ALK or MALT1 were detected as separate blue and red dots on ALCL and MALT lymphoma cases. Thus, ISH analyses of gene translocations can be conducted with a regular light microscope and the long term archiving of break-apart ISH slides can be achieved.     

The effect of reciprocal translocations on segregation and multivalent formation in autotetraploids of rye,Secale cereale

Chromosomal segregation, and the frequency of large multivalents in Secale cereale were studied in autotetraploid duplex translocation heterozygotes. Models for estimating expected segregations and frequencies of multivalents were developed incorporating the probabilities of different chromosomal segments being bound by chiasmata. It appeared that the segregation of the two translocations tested fitted quite well the expected corrected segregation ratio of approximately 1: 11.5: 1, suggesting that induced preferential pairing was not strong enough to enhance preferential segregation resulting from random translocation segregation. Interspecific hybrids with S. montanum carrying the same translocations showed strong preferential pairing, i.e. significant deviation from the expected ratios.Three translocations tested (two not tested for segregation) showed a decrease in multivalent frequency mainly attributable to preferential pairing, especially in cases where the breakpoint was near one chromosome end. Possible reasons why preferential pairing is expressed here and not in the segregations are discussed.     

Linkage group-chromosome correlation in Podospora anserina

Summary Two reciprocal translocations have been studied in an attempt to establish a one-to-one assignment of the seven linkage groups of P. anserina to specific chromosomes. Genetical data demonstrated clearly the relationships of the two translocations with three linkage groups. Cytological observations at meiosis in crosses heterozygous for the chromosomal interchanges showed the characteristic cross-like figures and confirmed the fact that the two translocations had one chromosome in common. The correspondence of the three largest chromosomes, including the one bearing the nucleolar organizer, with three well known linkage groups has thus been established. Evidence is also given that loci exhibiting a percentage of second division segregation as high as 98% are not at the end of the chromosomes.     

An efficient screening for terminal deletions and translocations of barley chromosomes added to common wheat

As a prerequisite to determine physical gene distances in barley chromosomes by deletion mapping, a reliable, fast and inexpensive approach was developed to detect terminal deletions and translocations in individual barley chromosomes added to the chromosome complement of common wheat. A refined fluorescence in situ hybridization (FISH) technique subsequent to N-banding made it possible to detect subtelomeric repeat sequences (HvT01) on all 14 chromosome arms of barley. Some chromosome arms could be distinguished individually based on the number of FISH signals or the intensity of terminal FISH signals. This allowed the detection and selection of deletions and translocations of barley chromosomes (exemplified by 7H and 4HL), which occurred in the progeny of the wheat lines containing a pair of individual barley chromosomes (or telosomes) and a single so-called gametocidal chromosome (2C) of Aegilops cylindrica. This chromosome is known to cause chromosomal breakage in the gametes in which it is absent. Terminal deletions and translocations in barley chromosomes were easily recognized in metaphase and even in interphase nuclei by a decrease in the number of FISH signals specific to the subtelomeric repeat. These aberrations were verified by genomic in situ hybridization. The same approach can be applied to select deletions and translocations of other barley chromosomes in wheat lines that are monosomic for the Ae. cylindrica chromosome 2C.     

Strukturheterozygotie beiVicia faba

Summary The karyotypes and the meiotic behaviour of two spontaneous reciprocal translocations and one pericentric inversion are described. One of these translocations was characterized by chiasma-formation in the interstitial-segments, the other was not. The types of orientation and distribution of the chromosomes from the chain-configurations in meta-anaphase I are specified, compared mutually and with those of translocation rings and chains in maize and the similarities and differences are pointed out. In the range of the heterozygous pericentric inversion there was no pairing in meiotic prophase and therefore no chiasma formation and sterility. It will be tried to cross especially one of the translocations with the inversion-type in order to rebuild the karyotype ofVicia faba. In this case it would be possible to distinguish between all five pairs of small chromosomes according to their morphological structure, a possibility very important in localizing chromosome aberrations on the chromosomes ofVicia faba.

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Beyond the beneficial effects of translocations as an effective tool for the genetic restoration of isolated populations

Translocations are becoming increasingly popular as appropriate management strategies for the genetic restoration of endangered species and populations. Although a few studies have shown that the introduction of novel alleles has reversed the detrimental effects of inbreeding over the short-term (i.e., genetic rescue), it is not clear how effective such translocations are for both maintaining neutral variation that may be adaptive in the future (i.e., genetic restoration) and increasing population viability over the long-term. In addition, scientists have expressed concerns regarding the potential genetic swamping of locally adapted populations, which may eliminate significant components of genetic diversity through the replacement of the target population by the source individuals used for translocations. Here we show that bird translocations into a wild population of greater prairie-chickens (Tympanuchus cupido pinnatus) in southeastern Illinois were effective in both removing detrimental variation associated with inbreeding depression as well as restoring neutral genetic variation to historical levels. Furthermore, we found that although translocations resulted in immediate increases in fitness, the demographic recovery and long-term viability of the population appears to be limited by the availability of suitable habitat. Our results demonstrate that although translocations can be effective management tools for the genetic restoration of wild populations on the verge of extinction, their long-term viability may not be guaranteed unless the initial conditions that led to most species declines (e.g., habitat loss) are reversed.     

Differences between genetic and physical centromere distances in the case of two genes for male sterility in barley

Summary Linkage studies with thirty translocations (one of the two chromosomes involved being number 4) in relation to msg24 (chromosome 4) and thirteen translocations (one of the two chromosomes involved being number 6) in relation to msg6 (chromosome 6) show without exception close linkage for all combinations tested. The results indicate that both genes are located genetically in or close to the centromere regions of their chromosomes.Cytological analysis of two BTT stocks (balanced tertiary trisomics) ascertained the respective chromosome arms (both msg24 and msg6 on the short arms) and revealed marked differences between genetic and physical centromere distances. The reason is obviously the high content of centromeric heterochromatin occupying both the chromosome arms involved.     

Does the Introduction of a New Player,the Endoplasmic Reticulum,Create More or Less Confusion in Understanding the Mechanism(s) of Pigmentary Organelle Translocations?

In 1925, Wilson listed, in his classic third edition of Cell in Development and Heredity, four theories for the morphological and physiological characteristics of cytoplasm; each theory provided some sort of explanation as to the mechanism(s) of organelle translocations. During the past twenty years, cell biologists have focused their attentions on the cell's cytoskeleton, microtrabecular lattice, and associated mechanochemical motors which drive organelles along cytoskeletal tracks. A number of cell types have been used to study organelle translocations, but chromatophores, pigment cells, from cold-blooded vertebrates have been one of the more popular models. This article reviews some of the research findings during the past twenty years, particularly those involving cytoplasmic elements: i.e, microfilaments, intermediate filaments, microtubules, and mechanochemical motors. In addition, it contrasts the proposed involvement of these elements in organelle translocations with the endoplasmic reticulum, a tubulovesicular organelle, which we recently demonstrated is responsible, through its elongation or retraction, for the translocations of carotenoid droplets in goldfish xanthophores and swordtail fish erythrophores. Here, the carotenoid droplets are not free in the cytoplasm and do not translocate via cytoskeletal tracks, but instead are attached to or are a part of the endoplasmic reticulum. On the other hand, carotenoid droplets of squirrel fish erythrophores are free in the cytoplasm and appear to translocate via microtubules. Finally, the rates of pigmentary organelle translocations are reviewed in light of the participation of the cytoskeletal elements with the endoplasmic reticulum.     

Non-reciprocal chromosomal bridge-induced translocation (BIT) by targeted DNA integration in yeast

Several experimental in vivo systems exist that generate reciprocal translocations between engineered chromosomal loci of yeast or Drosophila, but not without previous genome modifications. Here we report the successful induction of chromosome translocations in unmodified yeast cells via targeted DNA integration of the KAN^R selectable marker flanked by sequences homologous to two chromosomal loci randomly chosen on the genome. Using this bridge-induced translocation system, 2% of the integrants showed targeted translocations between chromosomes V-VIII and VIII-XV in two wild-type Saccharomyces cerevisiae strains. All the translocation events studied were found to be non-reciprocal and the fate of their chromosomal fragments that were not included in the translocated chromosome was followed. The recovery of discrete-sized fragments suggested multiple pathway repair of their free DNA ends. We propose that centromere-distal chromosome fragments may be processed by a break-induced replication mechanism ensuing in partial trisomy. The experimental feasibility of inducing chromosomal translocations between any two desired genetic loci in a eukaryotic model system will be instrumental in elucidating the molecular mechanism underlying genome rearrangements generated by DNA integration and the gross chromosomal rearrangements characteristic of many types of cancer.Electronic Supplementary Material Supplementary material is available for this article at     

Identification by Giemsa technique of the translocations separating cultivated rye from three wild species of Secale

Complete identification of the translocations involved in evolution of S. vavilovii, S. africanum and S. cereale from S. montanum was attained by meiotic analysis after Giemsa banding technique. Based on the original mitotic karyotype of S. montanum, the different chromosome arms were determined by centromere position and banding pattern of chromosomes for the four species and all of the possible interspecific hybrids. This first consistent scheme of cytogenetic relationships reveals: one translocation each, separating S. montanum from S. vavilovii and S. africanum, two translocations each, separating S. cereale from S. vavilovii and S. africanum, and three translocations each, separating S. cereale from S. montanum and S. africanum, respectively.