bluuebunny/crossref_metadata_2025 huggingface dataset:
A Method to Produce Radiation Hybrids for the D-Genome Chromosomes of Wheat (Triticum aestivum L.)
Authors: Riera-Lizarazu O. , Leonard J.M. , Tiwari V.K. , Kianian S.F.
Published: July 2010

Radiation hybrid (RH) mapping is based on radiation-induced chromosome breakage rather than meiotic recombination, as a means to induce marker segregation for mapping. To date, the implementation of this mapping approach in hexaploid (Triticum aestivum L.; 2n = 6x = 42; AABBDD) and tetraploid (T. turgidum L.; 2n = 4x = 28; AABB) wheat has concentrated on the production of mapping panels for individual chromosomes. In order to extend the usefulness of this approach, we have devised a method to produce panels for the simultaneous mapping of all chromosomes of the D subgenome of hexaploid wheat. In this approach, seeds of hexaploid wheat (AABBDD) are irradiated and the surviving plants are crossed to tetraploid wheat (AABB) to produce a mapping panel based on quasi-pentaploids (AABBD). Chromosome lesions in the A and B genomes are largely masked in the quasi-pentaploids due to the presence of A- and B-genome chromosomes from the tetraploid parent. On the other hand, the chromosomes from the D-genome are present in one copy (hemizygous) and allow radiation hybrid mapping of all D-genome chromosomes simultaneously. Our analyses showed that transmission of D-genome chromosomes was apparently normal and that radiation-induced chromosome breakage along D-genome chromosomes was homogeneous. Chromosome breakage levels between D-genome chromosomes were comparable except for chromosome 6D which suffered greater chromosome breakage. These results demonstrate the feasibility of constructing D-genome radiation hybrids (DGRHs) in wheat.
Recent and Frequent Insertions of Chloroplast DNA into Maize Nuclear Chromosomes
Authors: Roark L.M. , Hui A.Y. , Donnelly L. , Birchler J.A. , Newton K.J.
Published: July 2010

Organellar DNA transfer into the nucleus and incorporation into chromosomes are continuing processes. We have examined chloroplast DNA insertions in maize chromosomes using fluorescence in situ hybridization (FISH). Probes to detect the nuclear-plastid sequences (NUPTs) were generated using 14 overlapping fragments of the chloroplast genome. Using current FISH methods, detection of NUPTs on mitotic metaphase chromosomes requires relatively large insertions (>3 kb) with strong sequence similarity to chloroplast DNA. In the B73 inbred line, hybridization of each fragment separately resolved a total of 49 NUPT sites; fewer sites (30) were detectable when all the probes were combined. The combined set of probes was hybridized to 10 genetically useful maize inbred lines and identified 19–30 NUPTs in each line. In all but two of the lines, a prominent NUPT was present on the long arm of chromosome 5. Collectively, the number of NUPTs exceeds the number of nuclear-mitochondrial (NUMT) sites identified within the same set of inbred lines. A majority of the NUPTs are found at sites that are different from the NUMTs. Like NUMTs, the positions of the NUPTs vary greatly among the lines, suggesting that the transfers are recent as well as frequent. Thus, insertions of large segments of chloroplast and mitochondrial DNA are components of the dynamic fraction of maize nuclear genomes.
Single Integration and Spread of a Copia-Like Sequence Nested in rDNA Intergenic Spacers of Allium cernuum (Alliaceae)
Authors: Chester M. , Sykorova E. , Fajkus J. , Leitch A.R.
Published: July 2010

The 35S ribosomal DNA (rDNA) intergenic spacer (IGS) of Allium cernuum is examined. Initial sequencing of IGS clones revealed that some rDNA units contain a truncated retrotransposon sequence most similar to members of the Copia superfamily. Fluorescence in situ hybridisation (FISH) to metaphase chromosomes indicates that this element is dispersed along both pairs of major rDNA arrays. Southern hybridisation confirmed the presence of this ‘relic’ Copia-like element in more than 10% of 35S rDNA units, in the same position within the IGS. To measure the intragenomic divergence of the relic retroelement and its flanking sequences amongst different rDNA units, a 1.1-kb region was amplified and cloned. These data collectively point to a single origin for units containing the putative retrotransposon fragment. It is likely that units containing the putative retroelement increased in copy number and dispersed via rDNA homogenisation mechanisms, rather than by multiple retrotransposition events.
Development of Chromosome-Specific BAC Resources for Genomics of Bread Wheat
Authors: Šafář J. , Šimková H. , Kubaláková M. , Číhalíková J. , Suchánková P. , Bartoš J. , Doležel J.
Published: July 2010

The large bread wheat genome (1C ∼ 17 Gbp) contains a preponderance of repetitive DNA and the species is polyploid. These characteristics together serve to hamper the molecular analysis of the wheat genome. Its complexity can, however, be reduced by using flow cytometry to isolate individual chromosomes, and these can be exploited to construct chromosome-specific BAC libraries. Such libraries simplify the task of physical map construction, positional cloning and the targeted development of genetic markers. Rapid improvements in the efficiency and cost of DNA sequencing provide an opportunity to contemplate sequencing the wheat genome by preparing sequence-ready physical maps for each chromosome or chromosome arm in turn. The quality of the chromosome-specific libraries depends on their chromosome coverage and the mean insert size. First-generation libraries suffered from a relatively low mean insert size, but improvements to the protocol have generated a second wave of libraries with a significantly increased mean insert size and better chromosome coverage. Each chromosome (arm)-specific library is composed of a manageable number of clones, and so represents a practical tool in the area of wheat genomics.
Hypoxia-Ischemia Induces an Endogenous Reparative Response by Local Neural Progenitors in the Postnatal Mouse Telencephalon
Authors: Dizon Maria , Szele Francis , Kessler John A.
Published: July 2010

Perinatal hypoxia-ischemia in the preterm neonate commonly results in white matter injury for which there is no specific therapy. The subventricular zone (SVZ) of the brain harbors neural stem cells and more committed progenitors including oligodendroglial progenitor cells that might serve as replacement cells for treating white matter injury. Data from rodent models suggest limited replacement of mature oligodendroglia by endogenous cells. Rare newly born mature oligodendrocytes have been reported within the striatum, corpus callosum and infarcted cortex 1 month following hypoxia-ischemia. Whether these oligodendrocytes arise in situ or emigrate from the SVZ is unknown. We used a postnatal day 9 mouse model of hypoxia-ischemia, BrdU labeling of mitotic cells, immunofluorescence and time-lapse multiphoton microscopy to determine whether hypoxia-ischemia increases production of oligodendroglial progenitors within the SVZ with emigration toward injured areas. Although cells of the oligodendroglial lineage increased in the brain ipsilateral to hypoxic-ischemic injury, they did not originate from the SVZ but rather arose within the striatum and cortex. Furthermore, they resulted from proliferation within the striatum but not within the cortex. Thus, an endogenous regenerative oligodendroglial response to postnatal hypoxia-ischemia occurs locally, with minimal long-distance contribution by cells of the SVZ.
FISH Applications for Genomics and Plant Breeding Strategies in Tomato and Other Solanaceous Crops
Authors: Szinay D. , Bai Y. , Visser R. , de Jong H.
Published: July 2010

This paper describes the use of advanced fluorescence in situ hybridization (FISH) technologies for genomics and breeding of tomato and related Solanum species. The first part deals with the major determinants of FISH technology: (1) spatial resolution, which depends on the diffraction limit of the microscope and the type of chromosome, chromatin or isolated DNA fibres as target for the hybridisation; (2) the detection sensitivity, which is limited by the sensitivity and dynamic range of the CCD camera and the quality of the microscope, and the amplification system of the weak signals from tiny probe molecules; (3) simultaneous detection of multiple probes labelled directly or indirectly with up to 5 different fluorophores, whether or not in different combinations and/or mixed at different ratios. The power and usability of such multicolour FISH is indispensable when large numbers of bacterial artificial chromosomes (BACs) or other vectors with genomic DNA are available. Mapping of multiple BACs on chromosomes are powerful instruments confirming their assumed genetic position, whereas pooled BACs for a given chromosome arm will reveal the gaps between the BACs or derived contigs of their physical maps. Tandem and dispersed repeats, which are abundant in the genomes of most species, can be analysed in repeat bar coding FISH, showing the major blocks of repeats in heterochromatin and euchromatin areas. Repeat-rich areas of the chromosomes can also be demonstrated by hybridisation of probed Cot fractions of sheared genomic DNA; a powerful method to elucidate the heterochromatin domains for genomic studies. In addition, unlabelled Cot DNA, as blocking agent in BAC-FISH painting, suppresses repetitive sequences from the BACs to hybridise on the chromosomes. Cross-species BAC-FISH painting with labelled probes from tomato and potato BACs and hybridised on the chromosomes of related species, under appropriate conditions, is a powerful instrument to demonstrate chromosomal rearrangements, including inversions and translocations. The technology not only supports phylogenetic studies between the taxa under study but can also be helpful in breeding programs with crops containing introgressed regions from related species when linkage drag or meiotic pairing disturbances between the homoeologues are assumed. In the next steps in comparative genomics, we now can detect smaller chromosomal and DNA rearrangements, diminutions and amplifications of repeats and changes of the epigenetic status of introgressed regions.
A Comparative Analysis of Chromosome Pairing at Metaphase I in Interspecific Hybrids between Durum Wheat (Triticum turgidum L.) and the Most Widespread Aegilops Species
Authors: Cifuentes M. , Garcia-Agüero V. , Benavente E.
Published: July 2010

Homoeologous metaphase I (MI) associations in hybrids between durum wheat and its wild allotetraploid relatives Aegilops neglecta, Ae. triuncialis and Ae. ventricosa have been characterized by a genomic in situ hybridization procedure that allows simultaneous discrimination of A, B and wild species genomes. Earlier results in equivalent hybrids with the wild species Ae. cylindrica and Ae. geniculata have also been considered to comparatively assay the MI pairing pattern of the durum wheat × Aegilops interspecific combinations more likely to occur in nature. The general picture can be drawn as follows. A and B wheat genomes pair with each other less than the 2 wild constituent genomes do in any of the hybrid combinations examined. Interspecific wheat-wild associations account for 60–70% of total MI pairing in all hybrids, except in that derived from Ae. triuncialis, but the A genome is always the wheat partner most frequently involved in MI pairing with the wild homoeologues. Hybrids with Ae. cylindrica, Ae. geniculata and Ae. ventricosa showed similar reduced levels of MI association and virtually identical MI pairing patterns. However, certain recurrent differences were found when the pattern of homoeologous pairing of hybrids from either Ae. triuncialis or Ae. neglecta was contrasted to that observed in the other durum wheat hybrid combinations. In the former case, a remarkable preferential pairing between the wild species constituent genomes Ut and Ct seems to be the reason, whereas a general promotion of homoeologous pairing, qualitatively similar to that observed under the effect of the ph1c mutation, appears to occur in the hybrid with Ae. neglecta. It is further discussed whether the results reported here can be extrapolated to the corresponding bread wheat hybrid combinations.
Chromosome Dynamics in Meiotic Prophase I in Plants
Authors: Ronceret A. , Pawlowski W.P.
Published: July 2010

Early stages of meiotic prophase are characterized by complex and dramatic chromosome dynamics. Chromosome behavior during this period is associated with several critical meiotic processes that take place at the molecular level, such as recombination and homologous chromosome recognition and pairing. Studies to characterize specific patterns of chromosome dynamics and to identify their exact roles in the progression of meiotic prophase are only just beginning in plants. These studies are facilitated by advances in imaging technology in the recent years, including development of ultra-resolution three-dimensional and live microscopy methods. Studies conducted so far indicate that different chromosome regions exhibit different dynamics patterns in early prophase. In many species telomeres cluster at the nuclear envelope at the beginning of zygotene forming the telomere bouquet. The bouquet has been traditionally thought to facilitate chromosome pairing by bringing chromosome ends into close proximity, but recent studies suggest that its main role may rather be facilitating rapid movements of chromosomes during zygotene. In some species, including wheat and Arabidopsis, there is evidence that centromeres form pairs (couple) before the onset of pairing of chromosome arms. While significant advances have been achieved in elucidating the patterns of chromosome behavior in meiotic prophase I, factors controlling chromosome dynamics are still largely unknown and require further studies.
Chiasma Frequency Is Region Specific and Chromosome Conformation Dependent in a Rye Chromosome Added to Wheat
Authors: Naranjo T. , Valenzuela N.T. , Perera E.
Published: July 2010

In many plant species synapsis starts at, or close to, the chromosome ends and this has been considered to be related to the distal location of chiasmata. In this regard we have studied the meiotic behavior of rye chromosome pair 5R in a wheat background using fluorescence in situ hybridization. The use of different DNA probes allowed the identification of the 2 rye homologues, their centromeres and subtelomeric heterochromatic chromomeres, and the telomeres of all chromosomes in prophase I and metaphase I. Three types of plants were analyzed: homozygotes for the standard chromosome 5R, homozygotes for a deficient chromosome 5R (del5R) with only the proximal 30% of its long arm (del5RL) and heterozygotes. Synapsis of the deficient chromosome arm pair del5RL was completed in most meiocytes at pachytene but the number of chiasmata formed was much lower than in the intact 5RL arm. Deletion facilitated the migration of the telomere of the accompanying chromosome arm 5RS during bouquet organization. This was followed by an increase of synapsis and chiasma frequency in this arm with regard to its counterpart of the intact chromosome. Results demonstrate that crossover formation depends on the DNA sequence or the chromatin organization of each chromosome region and that homologous alignment, synapsis and chiasma formation may be conditioned by chromosome conformation.
An Easy Protocol for Studying Chromatin and Recombination Protein Dynamics during Arabidopsisthaliana Meiosis: Immunodetection of Cohesins, Histones and MLH1
Authors: Chelysheva L. , Grandont L. , Vrielynck N. , le Guin S. , Mercier R. , Grelon M.
Published: July 2010

Plant meiosis studies have enjoyed a fantastic boom in recent years with the use of Arabidopsis thaliana as a model not only for molecular genetics and genomics but also for cytogenetics. In this article we describe a new protocol for immunolabelling meiotic proteins that allows the detection of a large range of proteins on strongly spread chromosomes throughout the entire meiotic process. We used this method to immunodetect MLH1, a crucial component of the meiotic recombination machinery, and found that it can be visualised as foci from pachytene to diakinesis, where it co-localises with chiasmata. The mean MLH1 foci number per meiotic cell at diakinesis was 8.4 for WS-4 and 9.95 for Col-0, with the number of foci per bivalent ranging from 1 to 5. We also analysed MLH1 distribution within bivalents and found that they were not restricted to specific chromosomal regions. The analysis of MLH1 foci formation in the Atzip4 mutant, where class I crossover (CO) formation is prevented, revealed that residual chiasmata were not labelled by MLH1, strongly suggesting that MLH1 antibodies only label class I COs in Arabidopsis. It thus appears that the ‘obligatory CO’ is systematically labeled by MLH1 and is generated through the class I pathway.
Behavior of Centromeres in Univalents and Centric Misdivision in Wheat
Authors: Lukaszewski A.J.
Published: July 2010

Centromeres are responsible for the proper behavior of chromosomes in cell divisions. In meiosis the process is more complicated than in mitosis, as each chromosome in a bivalent has 2 sister centromeres and their behavior has to be strictly coordinated. Here, the behavior of sister centromeres in univalents in wheat is examined, showing that by metaphase I they often lose their coordination. This loss accelerates with the progression of anaphase I, leading to stable bipolar attachment and frequent separation of sister chromatids or to misdivision. Depending on the orientation of a univalent and its sister centromeres, misdivision may occur across the centromere region or across the pericentric chromatin. Chromosome fragments consisting of only the centromere region did not survive to the next generation. Midget chromosomes composed of the centromeres and parts of the pericentric chromatin did survive, but their transmission rates were low and appeared related to the amount of pericentric chromatin, probably because only the pericentric chromatin provides sister chromatid cohesion. As the cohesion of sister chromatids appears to be a function of the proximity to the kinetochore region, the definition of the centromere need not include pericentric regions.
Autologous Hematopoietic Stem Cell Transplantation for Acute Myeloid Leukemia in First Complete Remission: A Meta-Analysis of Randomized Trials
Authors: Wang Jing , Ouyang Jian , Zhou Rongfu , Chen Bing , Yang Yonggong
Published: July 2010

Background: For those patients who are not candidates for allogeneic stem cell transplantation (SCT) or who do not have an HLA-matched donor, it is unclear whether consolidation therapy with autologous SCT results in a survival benefit compared with further intensive post-remission non-myeloablative chemotherapy or no further therapy. Methods: A meta-analysis evaluating autologous SCT versus further chemotherapy or no treatment for acute myeloid leukemia (AML) in first complete remission (CR1) was completed. The search used the following combined search terms in Medline, Embase, the Cochrane Controlled Trials Register, the Cochrane Library, the Web of Science and the China National Knowledge Infrastructure. Results: Overall, 13 studies of 12 randomized controlled trials were identified. Four studies were in pediatric patients and 9 were in adults. For adults, AML in CR1 compared with non-SCT, lower relapse and higher transplantation-related mortality were associated with autologous SCT, a significant disease-free survival benefit of autologous SCT was documented, and there was no difference in overall survival when studies were pooled. For pediatric AML in CR1, there were no differences in relapse, transplantation-related mortality, disease-free survival and overall survival. Significantly less survival from relapse impairment was found for autologous SCT. Conclusion: Our results support the conclusion that autologous SCT should not be considered as the first-line post-remission therapy for AML patients in CR1.
The Ph1 Locus from Wheat Controls Meiotic Chromosome Pairing in Autotetraploid Rye (Secale cereale L.)
Authors: Lukaszewski A.J. , Kopecký D.
Published: July 2010

The Ph1 locus on chromosome 5B enforces strictly bivalent pairing in polyploid wheat, but the exact mechanism of its action remains unknown. Pairing restriction involves not only wheat homoeologues and all alien introgressions but also differentiated homologues. In this study we show that chromosome 5B with its Ph1 locus also controls chromosome pairing in autotetraploid rye by apparently restricting chiasma formation between dissimilar homologues. Unlike in wheat, the effect appears to be dosage-dependent, which may be a reflection of an interaction between Ph1 and the rye chromosome pairing control system. With 2 doses of Ph1 present, chiasmate pairing was severely restricted resulting in a significantly higher number of univalents and bivalents per cell than in the controls. The restrictions imposed by Ph1 virtually eliminated MI pairing of chromosome arms polymorphic for their C-band patterns and did not appear to affect arms with similar patterns. If the polymorphism for C-bands is taken as a measure of the overall chromosome similarity/divergence, such differences were recognized and acted upon by the Ph1 locus. The fact that Ph1 operates in rye in the same fashion as in polyploid wheats suggests that it controls some basic mechanism of chromosome recognition.
Silene latifolia: The Classical Model to Study Heteromorphic Sex Chromosomes
Authors: Kejnovsky E. , Vyskot B.
Published: July 2010

This review summarizes older as well as recent data about the model dioecious plant Silene latifolia. This plant has been the subject of more than one hundred years of research efforts and its most conspicuous property is huge and well differentiated heteromorphic sex chromosomes, XX in females and XY in males. Due to this property the S. latifolia sex chromosomes have been often used for cytogenetic studies as well as for flow sorting and laser microdissection. Nowadays S. latifolia is the focus of genomic studies, molecular mapping, phylogenetic and population genetics analyses.
Neocentrics and Holokinetics (Holocentrics): Chromosomes out of the Centromeric Rules
Authors: Guerra M. , Cabral G. , Cuacos M. , González-García M. , González-Sánchez M. , Vega J. , Puertas M.J.
Published: July 2010

The centromere appears as a single constriction at mitotic metaphase in most eukaryotic chromosomes. Holokinetic chromosomes are the exception to this rule because they do not show any centromeric constrictions. Holokinetic chromosomes are usually forgotten in most reviews about centromeres, despite their presence in a number of animal and plant species. They are generally linked to very intriguing and unusual mechanisms of mitosis and meiosis. Holokinetic chromosomes differ from monocentric chromosomes not only in the extension of the kinetochore plate, but also in many other peculiar karyological features, which could be understood as the ‘holokinetic syndrome’ that is reviewed in detail. Together with holokinetic chromosomes we review neocentromeric activity, a similarly intriguing case of regions able to pull chromosomes towards the poles without showing the main components reported to be essential to centromeric function. A neocentromere is a chromosomal region different from the true centromere in structure, DNA sequence and location, but is able to lead chromosomes to the cell poles in special circumstances. Neocentromeres have been reported in plants and animals showing different features. Both in humans and Drosophila, neocentric activity appears in somatic cells with defective chromosomes lacking a functional centromere. In most cases in plants, neocentromeres appear in chromosomes which have normal centromeres, but are active only during meiosis. Because of examples such as spontaneous or induced neocentromeres and holokinetic chromosomes, it is becoming less surprising that different structures and DNA sequences of centromeres appear in evolution.
A Common Founder Mutation in the EDA-A1 Gene in X-Linked Hypodontia
Authors: Kurban Mazen , Michailidis Eleni , Wajid Muhammad , Shimomura Yutaka , Christiano Angela M.
Published: July 2010

Background: X-linked recessive hypohidrotic ectodermal dysplasia (XLHED; OMIM 305100) is a rare genodermatosis characterized clinically by developmental abnormalities affecting the teeth, hair and sweat glands. Mutations in the EDA-A1 gene have been associated with XLHED. Recently, mutations in the EDA-A1 gene have also been implicated in isolated X-linked recessive hypodontia (XLRH; OMIM 313500). Methods: We analyzed the DNA from members of 3 unrelated Pakistani families with XLRH for mutations in the EDA-A1 gene through direct sequencing and performed haplotype analysis. Results: We identified a common missense mutation in both families designated c.1091T→C (p.M364T). Haplotype analysis revealed that this is a founder mutation in the 3 families. Conclusion: XLHED is a syndrome with variable clinical presentations that contain a spectrum of findings, including hypodontia. We suggest that XLRH should be grouped under XLHED as both share several phenotypic and genotypic similarities.
Development of a Molecular Cytogenetic Recombination Assay for Barley
Authors: Phillips D. , Nibau C. , Ramsay L. , Waugh R. , Jenkins G.
Published: July 2010

Distal localisation of chiasmata is common to many cereals and grasses, which consigns many genes of the complement to recombination backwaters. Releasing this potential untapped genetic variation for use in advanced breeding programmes is an ambitious and technically demanding challenge, necessitating controlled shifts in the distribution of crossover events. As part of a collaborative programme to manipulate recombination in barley, we are developing a robust and reliable molecular cytogenetic assay for recombination in this species, which will be used to gauge the success of our forward and reverse genetic interventions. Single-locus bacterial artificial chromosome clones and rDNA probes identify the 7 somatic chromosomes of the complement. Meiocytes at pachytene of meiosis were embedded in polyacrylamide and hybridised in situ with centromere and telomere probes, followed by immunolocalisation of the synaptonemal complex-associated protein Asy1 which highlights the bivalents’ axes. Optical sectioning, deconvolution and image analysis of the z-stacks of the nuclei allowed the disentanglement of each bivalent and the construction of an accurate meiotic ideogram. The landing of single-locus bacterial artificial chromosomes and the detection of late recombination proteins will complete the assay and provide a means of discerning subtle changes in recombination in this species.
Diversity of Chromosomal Karyotypes in Maize and Its Relatives
Authors: Albert P.S. , Gao Z. , Danilova T.V. , Birchler J.A.
Published: July 2010

Maize is a highly diverse species on the gene sequence level. With the recent development of methods to distinguish each of the 10 pairs of homologues in somatic root tip spreads, a wide collection of maize lines was subjected to karyotype analysis to serve as a reference for the community and to examine the spectrum of chromosomal features in the species. The core nested association mapping progenitor collection and additional selections of diversity lines were examined. Commonly used inbred lines were included in the analysis. The centromere 4 specific repeat and ribosomal RNA loci were invariant. The CentC centromere repeat exhibited extensive differences in quantity on any particular chromosome across lines. Knob heterochromatin was highly variable with locations at many sites in the genome. Lastly, representative examples from other species in the genus Zea (teosintes) were examined, which provide information on the evolution of chromosomal features.
Karyotyping in Melon (Cucumis melo L.) by Cross-Species Fosmid Fluorescence in situ Hybridization
Authors: Liu C. , Liu J. , Li H. , Zhang Z. , Han Y. , Huang S. , Jin W.
Published: July 2010

Chromosome identification is critical for cytogenetic research and will accelerate studies on genetic variation and breeding, especially for those species with relatively little sequence information. So far, no reliable cytological landmarks have been developed to distinguish individual chromosomes in melon. In this study, using FISH (fluorescence in situ hybridization) combined with comparative genome information, we selected 21 cucumber fosmids anchored by SSR markers as chromosome-specific cytological markers for melon chromosomes. Moreover, with the help of melon centromeric satellite DNA repeats CentM, 45S rDNA and 5S rDNA, sequential FISH with 3 sets of multi-fosmid cocktails were conducted on the same metaphase cell, which allowed us to simultaneously identify each of the 12 metaphase chromosomes of melon and a standardized melon karyotype of somatic metaphase chromosomes was constructed. Finally, we compared the distribution of 21 FISH-mapped fosmids between melon and cucumber chromosomes, which allows a better understanding of the evolutionary process shaping these 2 species. Our study provides a basis for cytological characterization of the melon genome and comparative genomics of Cucurbitaceae.
Constructing Defined Chromosome Segmental Duplications in Maize
Authors: Yu C. , Danilova T. , Zhang J. , Birchler J. , Peterson T.
Published: July 2010

We describe the production of chromosome segmental duplications and deletions of defined length in maize. The method utilizes a collection of previously isolated transposon-induced reciprocal translocations with sequence-defined breakpoints. These balanced translocations involve a first common breakpoint at the site of transposon Ac/fAc insertions on chromosome 1S, and a second variable endpoint elsewhere in the genome. Stocks containing translocations with different endpoints on the same chromosome arms were crossed together to generate heterozygous combinations. Subsequent meiotic segregation generates gametes that contain the original balanced translocations, or pairs of translocation chromosomes that are genetically unbalanced; i.e., they contain a duplication or deletion of the affected segment. Self-pollination produces progeny plants that are genetically balanced, or that contain 0 to 4 copies of the affected segment. The chromosome constitution of progeny plants can be determined using PCR primers flanking the translocation breakpoints. In addition, plants segregating genetically unbalanced gametes exhibit significant pollen grain abnormalities and thus can be easily detected in the field. In this way, we constructed 4 different segmental tetrasomic stocks involving genomic regions of approximately 7.8, 18.7, 21, and 42.6 Mb on chromosomes 5S, 5L, 5L, and 4L, respectively. FISH analysis using specific probes located within the affected segments confirms their aneuploid composition. These and similar lines containing precisely defined segmental duplications and deletions may be useful to study the genetic impact of gene dosage.
A Cytological Map of the Short Arm of Rye Chromosome 1R Constructed with 1R Dissection Stocks of Common Wheat and PCR-Based Markers
Authors: Gyawali Y.P. , Nasuda S. , Endo T.R.
Published: July 2010

The short arm of rye chromosome 1R (1RS) is introduced into many common wheat cultivars because of its agronomic importance. The gametocidal system has been used to produce dissection lines carrying segments of rye chromosome 1R. We focused on establishing more dissection lines for 1RS and on obtaining PCR-based markers specific to 1RS. We established 66 1RS dissection lines carrying 1RS segments of chromosome 1R derived from a common wheat cultivar ‘Burgas 2’ and obtained 27 markers. We conducted a PCR analysis using the dissection lines and markers, and divided 1RS into 17 regions separated by the breakpoints. Comparison of the ‘Burgas 2’ 1RS map with another map of 1RS derived from ‘Imperial’ rye implied a restructuring between the 2 1RS chromosomes.
Higher Organization and Histone Modification of the Plant Nucleus and Chromosome
Authors: Wako T. , Fukui K.
Published: July 2010

Plants have a wide range of genome sizes. The length of each DNA molecule is usually much longer than the diameter of the cell and the length of each metaphase chromosome is effectively shortened to progress through mitosis. Thus some questions arise, such as: How is genomic DNA folded and shortened into chromosomes? What kind of proteins and/or their modifications contribute to chromosome structure? Are there any upper limits for the ratio of DNA volume to nuclear volume? This review attempts to answer these questions based on recent advances in chromosome research. Genomic DNA is first folded into nucleosomal fibers and then superfolded into metaphase chromosomes to sufficiently shorten its length to less than the upper limit for normal progression of cell division. Nucleosomes play structural roles, not only for DNA folding, but also for determination of euchromatin, heterochromatin, and centromeres, together with post-translational modifications and replacement of core histones with histone variants, and for the regulation of their structure and transcriptional status. More than 200 proteins of human metaphase chromosomes have been identified, including 5 types of nucleosome histones. They are categorized into 4 groups, and a 4-layer model of the human metaphase chromosome has been developed. There are upper limits for DNA volume. In all plants examined to date the DNA volume does not exceed 3% of the nuclear volume. Histone modification also has an impact on the spatial distribution of chromosomes within a nucleus, which seems to be related to the plant genome size. These points are discussed as well, as they are essential to maintain proper nuclear functions.
Integration of Genetic, Physical, and Cytogenetic Maps for Brassica rapa Chromosome A7
Authors: Xiong Z. , Kim J.S. , Pires J.C.
Published: July 2010

Bacterial artificial chromosome (BAC) contigs have been genetically mapped to the 10 linkage groups of Brassica rapa by BAC end sequences (BES). To integrate the genetic, physical, and cytogenetic maps, fluorescence in situ hybridization (FISH) was used to anchor the assembly of BAC contigs onto Brassica chromosomes using representative BACs. This BAC-FISH approach can be used to identify chromosome arms on separate mitotic metaphase chromosomes or to map multiple BACs to single long pachytene chromosomes. As part of an international consortium that is sequencing the B. rapa genome, we integrated the linkage and physical maps with the B. rapa cytogenetic map for chromosome A7 by hybridizing BACs to mitotic chromosomes and along the length of pachytene chromosome spreads. A total of 31 BACs that were putatively located on A7 were used as probes for FISH analyses; however, only 19 BACs mapped unambiguously to A7 while the remaining BACs either mapped to other chromosomes or hybridized to multiple locations. We then created a multicolor FISH cocktail of 16 BAC probes to simultaneously hybridize the entire length of the A7 chromosome. We successfully applied the 16 A7 BAC probe mix to B. rapa, B. oleracea, and domesticated and resynthesized genotypes of B. napus to demonstrate that this approach can facilitate studies of genome evolution by integrating the genetic, physical, and cytogenetic maps among closely related species of Brassica.
Skin and Nail Responses after 1 Year of Infliximab Therapy in Patients with Moderate-to-Severe Psoriasis: A Retrospective Analysis of the EXPRESS Trial
Authors: Reich Kristian , Ortonne Jean-Paul , Kerkmann Urs , Wang Yanxin , Saurat Jean-Hilaire , Papp Kim , Langley Richard , Griffiths Christopher E.M.
Published: July 2010

Background: The EXPRESS study demonstrated the initial efficacy of infliximab in psoriasis affecting the skin and nails. Objective: To further assess how patients with a positive initial response to infliximab respond to 1 year of continuous infliximab treatment. Methods: A retrospective analysis of patients with moderate-to-severe plaque and nail psoriasis who initiated and continued infliximab treatment up to week 46 was conducted. Results: Among all nail psoriasis patients receiving 1 year of infliximab (n = 186), 74.6 and 54.1% achieved at least 75 or 90% improvement in the Psoriasis Area and Severity Index (PASI) at week 50. These PASI-75 (n = 138) and PASI-90 (n = 100) responders had respective mean improvements from baseline to week 50 of 93.6 and 97.3% for the PASI, 90.6 and 94.1% for the Dermatology Life Quality Index (DLQI) and 78.2 and 80.3% for the Nail Psoriasis Severity Index (NAPSI). Conclusions: Infliximab treatment for 1 year produced sustained improvement in PASI, DLQI and NAPSI scores.
A Gender Comparison of Postobstructive Injury in the Rat Kidney
Authors: Quinlan Mark R. , Cronin Peter , Daly Padraig J. , Watson Ronald W.G. , Manucha Walter , Docherty Neil G. , Fitzpatrick John M.
Published: July 2010

Background/Aims: Unilateral ureteral obstruction (UUO) results in renal injury. Studies report increased injury indices in male rats following UUO. Our study examined whether this gender-based renal response to UUO was reflected in sustained differences following relief of obstruction. Methods: Adult male/female rats (200–400 g) were subjected to either sham surgery (S/RN) or UUO (UUO/RN). At 24 h, obstruc- tion was relieved and all animals underwent contralateral nephrectomy. Five days after initial surgery, animals were placed in metabolic cages and given water ad libitum for 24 h followed by a 24-hour period of complete water restriction. On day 7, animals were euthanized and samples harvested. Tubular injury, urinary volume/osmolality, creatinine clearance, plasma arginine vasopressin, renal medullary V2 receptor and aquaporin 2 (AQP2) expression were measured. Results: Male UUO/RN rats showed increased renal apoptotic injury and reduced creatinine clearance rates (glomerular filtration rate) vs. females. No gender-dependent differences were observed in urinary osmolality or concentrating ability. AQP2 expression increased post-obstruction. Conclusion: Increased injury in males following UUO remains manifest during early recovery after release of obstruction. Despite this, the grade of postobstructive diuresis is not significantly altered between sexes. This may reflect reduced glomerular filtration rate and elevated AQP2 in male rats.
Cardiogenic Shock due to Tachycardiomyopathy after Heart Transplantation: Successful Treatment with Ivabradine
Authors: Zwicker C. , Becker M. , Lepper W. , Koch K.C. , Westenfeld R.
Published: July 2010

Tachycardia-induced cardiomyopathy refers to an impairment in left-ventricular function due to chronic or prolonged tachycardia. We describe a heart transplant patient who developed cardiogenic shock due to tachycardia-induced cardiomyopathy. Low-output failure was further aggravated by administration of a short-acting β-blocker during invasive hemodynamic monitoring. In contrast, heart rate control by administration of increasing doses of ivabradine supported recovery from cardiogenic shock and led to an improvement in the patient’s clinical condition as well as left-ventricular function during follow-up.
Sumoylation of Drosophila Transcription Factor STAT92E
Authors: Grönholm Juha , Ungureanu Daniela , Vanhatupa Sari , Rämet Mika , Silvennoinen Olli
Published: July 2010

STAT92E is an essential transcription factor in Drosophila melanogaster for the development of several organs and the immune system. The JAK/STAT pathway employs different evolutionary conserved regulatory mechanisms to control biological processes. Numerous transcription factors in both mammals and invertebrates have been shown to be either activated or inhibited by a covalent modification with a small ubiquitin-like modifier (Sumo). Here, we show that Drosophila STAT92E is modified by Sumo at a single lysine residue 187 in S2 cells. Mutation of Lys187 increases the transcriptional activity of STAT92E, thus suggesting that sumoylation of STAT92E has a repressive role in the regulation of the JAK/STAT pathway in Drosophila melanogaster.
Prospective Study of Obstructive Sleep Apnea and Incident Coronary Heart Disease and Heart Failure
Authors: Gottlieb Daniel J. , Yenokyan Gayane , Newman Anne B. , O'Connor George T. , Punjabi Naresh M. , Quan Stuart F. , Redline Susan , Resnick Helaine E. , Tong Elisa K. , Diener-West Marie , Shahar Eyal
Published: July 2010

Background—

Clinic-based observational studies in men have reported that obstructive sleep apnea is associated with an increased incidence of coronary heart disease. The objective of this study was to assess the relation of obstructive sleep apnea to incident coronary heart disease and heart failure in a general community sample of adult men and women.

Methods and Results—

A total of 1927 men and 2495 women ≥40 years of age and free of coronary heart disease and heart failure at the time of baseline polysomnography were followed up for a median of 8.7 years in this prospective longitudinal epidemiological study. After adjustment for multiple risk factors, obstructive sleep apnea was a significant predictor of incident coronary heart disease (myocardial infarction, revascularization procedure, or coronary heart disease death) only in men ≤70 years of age (adjusted hazard ratio 1.10 [95% confidence interval 1.00 to 1.21] per 10-unit increase in apnea-hypopnea index [AHI]) but not in older men or in women of any age. Among men 40 to 70 years old, those with AHI ≥30 were 68% more likely to develop coronary heart disease than those with AHI <5. Obstructive sleep apnea predicted incident heart failure in men but not in women (adjusted hazard ratio 1.13 [95% confidence interval 1.02 to 1.26] per 10-unit increase in AHI). Men with AHI ≥30 were 58% more likely to develop heart failure than those with AHI <5.

Conclusions—

Obstructive sleep apnea is associated with an increased risk of incident heart failure in community-dwelling middle-aged and older men; its association with incident coronary heart disease in this sample is equivocal.
Mineralocorticoid Accelerates Transition to Heart Failure With Preserved Ejection Fraction Via “Nongenomic Effects”
Authors: Mohammed Selma F. , Ohtani Tomohito , Korinek Josef , Lam Carolyn S.P. , Larsen Katarina , Simari Robert D. , Valencik Maria L. , Burnett John C. , Redfield Margaret M.
Published: July 2010

Background—

Mechanisms promoting the transition from hypertensive heart disease to heart failure with preserved ejection fraction are poorly understood. When inappropriate for salt status, mineralocorticoid (deoxycorticosterone acetate) excess causes hypertrophy, fibrosis, and diastolic dysfunction. Because cardiac mineralocorticoid receptors are protected from mineralocorticoid binding by the absence of 11-β hydroxysteroid dehydrogenase, salt-mineralocorticoid–induced inflammation is postulated to cause oxidative stress and to mediate cardiac effects. Although previous studies have focused on salt/nephrectomy in accelerating mineralocorticoid-induced cardiac effects, we hypothesized that hypertensive heart disease is associated with oxidative stress and sensitizes the heart to mineralocorticoid, accelerating hypertrophy, fibrosis, and diastolic dysfunction.

Methods and Results—

Cardiac structure and function, oxidative stress, and mineralocorticoid receptor–dependent gene transcription were measured in sham-operated and transverse aortic constriction (studied 2 weeks later) mice without and with deoxycorticosterone acetate administration, all in the setting of normal-salt diet. Compared with sham mice, sham plus deoxycorticosterone acetate mice had mild hypertrophy without fibrosis or diastolic dysfunction. Transverse aortic constriction mice displayed compensated hypertensive heart disease with hypertrophy, increased oxidative stress (osteopontin and NOX4 gene expression), and normal systolic function, filling pressures, and diastolic stiffness. Compared with transverse aortic constriction mice, transverse aortic constriction plus deoxycorticosterone acetate mice had similar left ventricular systolic pressure and fractional shortening but more hypertrophy, fibrosis, and diastolic dysfunction with increased lung weights, consistent with heart failure with preserved ejection fraction. There was progressive activation of markers of oxidative stress across the groups but no evidence of classic mineralocorticoid receptor–dependent gene transcription.

Conclusions—

Pressure-overload hypertrophy sensitizes the heart to mineralocorticoid excess, which promotes the transition to heart failure with preserved ejection fraction independently of classic mineralocorticoid receptor–dependent gene transcription.
Enalapril in Infants With Single Ventricle
Authors: Hsu Daphne T. , Zak Victor , Mahony Lynn , Sleeper Lynn A. , Atz Andrew M. , Levine Jami C. , Barker Piers C. , Ravishankar Chitra , McCrindle Brian W. , Williams Richard V. , Altmann Karen , Ghanayem Nancy S. , Margossian Renee , Chung Wendy K. , Border William L. , Pearson Gail D. , Stylianou Mario P. , Mital Seema
Published: July 2010

Background—

Angiotensin-converting enzyme inhibitor therapy improves clinical outcome and ventricular function in adults with heart failure. Infants with single-ventricle physiology have poor growth and are at risk for abnormalities in ventricular systolic and diastolic function. The ability of angiotensin-converting enzyme inhibitor therapy to preserve ventricular function and improve somatic growth and outcomes in these infants is unknown.

Methods and Results—

The Pediatric Heart Network conducted a double-blind trial involving 230 infants with single-ventricle physiology randomized to receive enalapril (target dose 0.4 mg · kg
−1
· d
−1
) or placebo who were followed up until 14 months of age. The primary end point was weight-for-age
z
score at 14 months. The primary analysis was intention to treat. A total of 185 infants completed the study. There were 24 and 21 withdrawals or deaths in the enalapril and placebo groups, respectively (
P
=0.74). Weight-for-age
z
score was not different between the enalapril and placebo groups (mean±SE −0.62±0.13 versus −0.42±0.13,
P
=0.28). There were no significant group differences in height-for-age
z
score, Ross heart failure class, brain natriuretic peptide concentration, Bayley scores of infant development, or ventricular ejection fraction. The incidence of death or transplantation was 13% and did not differ between groups. Serious adverse events occurred in 88 patients in the enalapril group and 87 in the placebo group.

Conclusions—

Administration of enalapril to infants with single-ventricle physiology in the first year of life did not improve somatic growth, ventricular function, or heart failure severity. The results of this randomized trial do not support the routine use of enalapril in this population.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00113087.