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Littérature scientifique sur le sujet « Structure du chromosome »

Auteur : Grafiati
Publié le 21 décembre 2024

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Articles de revues sur le sujet "Structure du chromosome"

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Tamang, Sonam. « Principles and Applications of Fetal Chromosome Number and Structure Analysis ». Sriwijaya Journal of Obstetrics and Gynecology 1, no 2 (20 décembre 2023) : 39–43. http://dx.doi.org/10.59345/sjog.v1i2.83.

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A crucial diagnostic technique employed in prenatal diagnosis is examining the quantity and arrangement of fetal chromosomes. The fundamental premise of this study is to determine the chromosomal count in the fetal cells and detect any genetic or chromosomal abnormalities that may be present. A total of 46 chromosomes are typically present in the human body, organized into 23 pairs. These pairs include one pair of sex chromosomes and 22 pairs of autosomal chromosomes. This study enables the identification of chromosomal abnormalities, such as trisomy (the presence of an additional chromosome) and monosomy (the absence of a chromosome), which can have an impact on the health of the fetus. In addition to determining the number of chromosomes, this examination can also detect structural chromosome abnormalities like translocations, deletions, and duplications, which might potentially affect the health of the fetus. This investigation's findings provide significant insights to both patients and clinicians, enabling them to make more informed choices about continuing the pregnancy and receiving appropriate medical attention if genetic abnormalities are detected. This study can also be utilized for the identification of particular genetic illnesses associated with specific gene mutations, thereby aiding in treatment strategizing and postnatal readiness.
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Gasser, Susan M. « Chromosome Structure : Coiling up chromosomes ». Current Biology 5, no 4 (avril 1995) : 357–60. http://dx.doi.org/10.1016/s0960-9822(95)00071-6.

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Eidelman, Yuri, Ilya Salnikov, Svetlana Slanina et Sergey Andreev. « Chromosome Folding Promotes Intrachromosomal Aberrations under Radiation- and Nuclease-Induced DNA Breakage ». International Journal of Molecular Sciences 22, no 22 (10 novembre 2021) : 12186. http://dx.doi.org/10.3390/ijms222212186.

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The long-standing question in radiation and cancer biology is how principles of chromosome organization impact the formation of chromosomal aberrations (CAs). To address this issue, we developed a physical modeling approach and analyzed high-throughput genomic data from chromosome conformation capture (Hi-C) and translocation sequencing (HTGTS) methods. Combining modeling of chromosome structure and of chromosomal aberrations induced by ionizing radiation (IR) and nuclease we made predictions which quantitatively correlated with key experimental findings in mouse chromosomes: chromosome contact maps, high frequency of cis-translocation breakpoints far outside of the site of nuclease-induced DNA double-strand breaks (DSBs), the distinct shape of breakpoint distribution in chromosomes with different 3D organizations. These correlations support the heteropolymer globule principle of chromosome organization in G1-arrested pro-B mouse cells. The joint analysis of Hi-C, HTGTS and physical modeling data offers mechanistic insight into how chromosome structure heterogeneity, globular folding and lesion dynamics drive IR-recurrent CAs. The results provide the biophysical and computational basis for the analysis of chromosome aberration landscape under IR and nuclease-induced DSBs.
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Matsunaga, Sachihiro, et Kiichi Fukui. « The chromosome peripheral proteins play an active role in chromosome dynamics ». BioMolecular Concepts 1, no 2 (1 août 2010) : 157–64. http://dx.doi.org/10.1515/bmc.2010.018.

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AbstractThe chromosome periphery is a chromosomal structure that covers the surface of mitotic chromosomes. The structure and function of the chromosome periphery has been poorly understood since its first description in 1882. It has, however, been proposed to be an insulator or barrier to protect chromosomes from subcellular substances and to act as a carrier of nuclear and nucleolar components to direct their equal distribution to daughter cells because most chromosome peripheral proteins (CPPs) are derived from the nucleolus or nucleus. Until now, more than 30 CPPs were identified in mammalians. Recent immunostaining analyses of CPPs have revealed that the chromosome periphery covers the centromeric region of mitotic chromosomes in addition to telomeres and regions between two sister chromatids. Knockdown analyses of CPPs using RNAi have revealed functions in chromosome dynamics, including cohesion of sister chromatids, kinetochore-microtubule attachments, spindle assembly and chromosome segregation. Because most CPPs are involved in various subcellular events in the nucleolus or nuclear at interphase, a temporal and spatial-specific knockdown method of CPPs in the chromosome periphery will be useful to understand the function of chromosome periphery in cell division.
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Spell, R. M., et C. Holm. « Nature and distribution of chromosomal intertwinings in Saccharomyces cerevisiae ». Molecular and Cellular Biology 14, no 2 (février 1994) : 1465–76. http://dx.doi.org/10.1128/mcb.14.2.1465-1476.1994.

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To elucidate yeast chromosome structure and behavior, we examined the breakage of entangled chromosomes in DNA topoisomerase II mutants by hybridization to chromosomal DNA resolved by pulsed-field gel electrophoresis. Our study reveals that large and small chromosomes differ in the nature and distribution of their intertwinings. Probes to large chromosomes (450 kb or larger) detect chromosome breakage, but probes to small chromosomes (380 kb or smaller) reveal no breakage products. Examination of chromosomes with one small arm and one large arm suggests that the two arms behave independently. The acrocentric chromosome XIV breaks only on the long arm, and its preferred region of breakage is approximately 200 kb from the centromere. When the centromere of chromosome XIV is relocated, the preferred region of breakage shifts accordingly. These results suggest that large chromosomes break because they have long arms and small chromosomes do not break because they have small arms. Indeed, a small metacentric chromosome can be made to break if it is rearranged to form a telocentric chromosome with one long arm or a ring with an "infinitely" long arm. These results suggest a model of chromosomal intertwining in which the length of the chromosome arm prevents intertwinings from passively resolving off the end of the arm during chromosome segregation.
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Spell, R. M., et C. Holm. « Nature and distribution of chromosomal intertwinings in Saccharomyces cerevisiae. » Molecular and Cellular Biology 14, no 2 (février 1994) : 1465–76. http://dx.doi.org/10.1128/mcb.14.2.1465.

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To elucidate yeast chromosome structure and behavior, we examined the breakage of entangled chromosomes in DNA topoisomerase II mutants by hybridization to chromosomal DNA resolved by pulsed-field gel electrophoresis. Our study reveals that large and small chromosomes differ in the nature and distribution of their intertwinings. Probes to large chromosomes (450 kb or larger) detect chromosome breakage, but probes to small chromosomes (380 kb or smaller) reveal no breakage products. Examination of chromosomes with one small arm and one large arm suggests that the two arms behave independently. The acrocentric chromosome XIV breaks only on the long arm, and its preferred region of breakage is approximately 200 kb from the centromere. When the centromere of chromosome XIV is relocated, the preferred region of breakage shifts accordingly. These results suggest that large chromosomes break because they have long arms and small chromosomes do not break because they have small arms. Indeed, a small metacentric chromosome can be made to break if it is rearranged to form a telocentric chromosome with one long arm or a ring with an "infinitely" long arm. These results suggest a model of chromosomal intertwining in which the length of the chromosome arm prevents intertwinings from passively resolving off the end of the arm during chromosome segregation.
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Uchida, Tetsuya, Naoto Ishihara, Hiroyuki Zenitani, Keiichiro Hiratsu et Haruyasu Kinashi. « Circularized Chromosome with a Large Palindromic Structure in Streptomyces griseus Mutants ». Journal of Bacteriology 186, no 11 (1 juin 2004) : 3313–20. http://dx.doi.org/10.1128/jb.186.11.3313-3320.2004.

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ABSTRACT Streptomyces linear chromosomes display various types of rearrangements after telomere deletion, including circularization, arm replacement, and amplification. We analyzed the new chromosomal deletion mutants Streptomyces griseus 301-22-L and 301-22-M. In these mutants, chromosomal arm replacement resulted in long terminal inverted repeats (TIRs) at both ends; different sizes were deleted again and recombined inside the TIRs, resulting in a circular chromosome with an extremely large palindrome. Short palindromic sequences were found in parent strain 2247, and these sequences might have played a role in the formation of this unique structure. Dynamic structural changes of Streptomyces linear chromosomes shown by this and previous studies revealed extraordinary strategies of members of this genus to keep a functional chromosome, even if it is linear or circular.
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Pelttari, Jeanette, Mary-Rose Hoja, Li Yuan, Jian-Guo Liu, Eva Brundell, Peter Moens, Sabine Santucci-Darmanin et al. « A Meiotic Chromosomal Core Consisting of Cohesin Complex Proteins Recruits DNA Recombination Proteins and Promotes Synapsis in the Absence of an Axial Element in Mammalian Meiotic Cells ». Molecular and Cellular Biology 21, no 16 (15 août 2001) : 5667–77. http://dx.doi.org/10.1128/mcb.21.16.5667-5677.2001.

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ABSTRACT The behavior of meiotic chromosomes differs in several respects from that of their mitotic counterparts, resulting in the generation of genetically distinct haploid cells. This has been attributed in part to a meiosis-specific chromatin-associated protein structure, the synaptonemal complex. This complex consist of two parallel axial elements, each one associated with a pair of sister chromatids, and a transverse filament located between the synapsed homologous chromosomes. Recently, a different protein structure, the cohesin complex, was shown to be associated with meiotic chromosomes and to be required for chromosome segregation. To explore the functions of the two different protein structures, the synaptonemal complex and the cohesin complex, in mammalian male meiotic cells, we have analyzed how absence of the axial element affects early meiotic chromosome behavior. We find that the synaptonemal complex protein 3 (SCP3) is a main determinant of axial-element assembly and is required for attachment of this structure to meiotic chromosomes, whereas SCP2 helps shape the in vivo structure of the axial element. We also show that formation of a cohesin-containing chromosomal core in meiotic nuclei does not require SCP3 or SCP2. Our results also suggest that the cohesin core recruits recombination proteins and promotes synapsis between homologous chromosomes in the absence of an axial element. A model for early meiotic chromosome pairing and synapsis is proposed.
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Anderson, Lorinda K., Naser Salameh, Hank W. Bass, Lisa C. Harper, W. Z. Cande, Gerd Weber et Stephen M. Stack. « Integrating Genetic Linkage Maps With Pachytene Chromosome Structure in Maize ». Genetics 166, no 4 (1 avril 2004) : 1923–33. http://dx.doi.org/10.1093/genetics/166.4.1923.

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Abstract Genetic linkage maps reveal the order of markers based on the frequency of recombination between markers during meiosis. Because the rate of recombination varies along chromosomes, it has been difficult to relate linkage maps to chromosome structure. Here we use cytological maps of crossing over based on recombination nodules (RNs) to predict the physical position of genetic markers on each of the 10 chromosomes of maize. This is possible because (1) all 10 maize chromosomes can be individually identified from spreads of synaptonemal complexes, (2) each RN corresponds to one crossover, and (3) the frequency of RNs on defined chromosomal segments can be converted to centimorgan values. We tested our predictions for chromosome 9 using seven genetically mapped, single-copy markers that were independently mapped on pachytene chromosomes using in situ hybridization. The correlation between predicted and observed locations was very strong (r2 = 0.996), indicating a virtual 1:1 correspondence. Thus, this new, high-resolution, cytogenetic map enables one to predict the chromosomal location of any genetically mapped marker in maize with a high degree of accuracy. This novel approach can be applied to other organisms as well.
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Wolf, Klaus Werner, Karel Novák et František Marec. « Chromosome structure in spermatogenesis of Anabolia furcata (Trichoptera) ». Genome 35, no 1 (1 février 1992) : 46–52. http://dx.doi.org/10.1139/g92-008.

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The structure of metaphase chromosomes was analysed in spermatogonia and spermatocytes of the caddis-fly, Anabolia furcata (Trichoptera: Limnephilidae), using ultrathin serial sections and electron microscopy. In metaphase spermatogonia, about 40% of the chromosomal length was covered with a compact kinetochore plate. Subjectively estimated, secondary spermatocytes were not significantly different in this respect. However, in primary spermatocytes, each bivalent showed four kinetochores, two at each poleward surface, connected with the chromosome. The kinetochores were not located at the chromosome portions most proximal to the spindle poles, but attached laterally in a more equatorial position. When the orientation of individual kinetochore plates in metaphase I bivalents was not roughly at right angles with respect to the spindle axis, gaps and holes were visible in the plates. This possibly indicates the presence of compound kinetochores in A. furcata. The center of the bivalents contains less dense material than the periphery. The structural features of chromosomes in this Trichoptera species are very similar to those described in Lepidotera species with a comparable chromosome number. Taken together with similarities in other karyotype characteristics, such as female heterogamety and the lack of chiasmata in female meiosis, this further corroborates the notion that Lepidoptera and Trichoptera have strong phylogenetic affinities.Key words: caddis-fly, metaphase chromosomes, kinetochore, microtubules, spindle.
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Thèses sur le sujet "Structure du chromosome"

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Patra, Gurudatt. « Structure of mitotic chromosome and the role of condensin protein in the structural organization of chromosomes ». Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAJ020.

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Au cours de la mitose, la chromatine interphasique subit une compaction massive en structures en forme de bâtonnets. Les condensines sont des complexes protéiques dont on sait qu'ils jouent un rôle majeur dans l'organisation des chromosomes mitotiques. Les eucaryotes possèdent deux complexes de condensines conservés, à savoir les condensines 1 et 2. Des études in vitro sur des modèles d'ADN nus montrent que les condensines ont une activité d'extrusion de boucles dans l'organisation des chromosomes. Cependant, il reste encore beaucoup à explorer en ce qui concerne l'étude de la fonction des condensines dans l'environnement encombré de la chromatine. Nous avons utilisé la technologie halo tag où le domaine SMC2 des condensines est marqué par fluorescence à l'aide d'un ligand halo TMR. Cette approche nous aide à localiser les régions riches en condensines dans les chromosomes mitotiques partiellement décondensés en utilisant la cryo-microscopie en lumière à l'intérieur des chromosomes vitrifiés pour les études de cryo-tomographie électronique. Nos tomographies montrent les complexes de condensine dans l'environnement chromatinien. Cela ouvre une fenêtre sur l'étude de l'activité de liaison à l'ADN de la condensine, l'oligomérisation ou le regroupement de la condensine et son interaction avec d'autres composants non histoniques des chromosomes mitotiques
During mitosis, the interphase chromatin undergoes a massive round of compaction into rod-shaped structures. Condensins are protein complexes that have been known to play a major role in mitotic chromosome organization. Eukaryotes have two conserved condensin complexes, namely condensin 1 and 2. In vitro studies on naked DNA templates show evidence for loop extrusion activity of condensins in chromosome organization. However, there is still a lot to explore regarding the study of condensin function inside the crowded chromatin environment. We have used halo tag technology where the SMC2 domain of condensins is tagged to fluorescently label using a halo TMR ligand. This approach helps us to locate condensin-rich regions in partially decondensed mitotic chromosomes using cryo-light microscopy inside the vitrified chromosomes for cryo-electron tomography studies. Our tomograms show condensin complexes inside the chromatin environment. This opens up a window into the study of DNA binding activity of condensin, the oligomerization or clustering of condensin and its interaction with other non-histone components of mitotic chromosomes
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Stear, Jeffrey Hamilton. « Studies of chromosome structure and movement in C. elegans / ». Thesis, Connect to this title online ; UW restricted, 2003. http://hdl.handle.net/1773/5056.

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Francki, Michael G. « The midget chromosome as a model to study cereal chromosome structure / ». Title page, contents and summary only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phf823.pdf.

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Woodward, Jessica Christina. « Cell-lineage-specific chromosomal instability in condensin II mutant mice ». Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/22921.

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In order to equally segregate their genetic material into daughter cells during mitosis, it is essential that chromosomes undergo major restructuring to facilitate compaction. However, the process of transforming diffuse, entangled interphase chromatin into discrete, highly organised chromosomal structures is extremely complex, and currently not completely understood. The complexes involved in chromatin compaction and sister chromatid decatenation in preparation for mitosis include condensins I and II. Mutations in condensin subunits have been identified in human tumours, reflecting the importance of accurate cell division in the prevention of aneuploidy and tumour formation. Most mutations described in TCGA (The Cancer Genome Atlas) and COSMIC (Catalogue of Somatic Mutations in Cancer) are missense, and therefore likely to only partially affect condensin function. Most functional genetic studies of condensin, however, have used loss of function systems, which typically cause severe chromosome segregation defects and cell death. Mice carrying global hypomorphic mutations within the kleisin subunit of the condensin II complex develop T cell lymphomas. The Caph2nes/nes mouse model is therefore a good system for understanding how condensin dysfunction can influence tumourigenesis. However, little is known about which cellular processes are affected in mutant cells before transformation. I therefore set out to use the Caph2nes/nes mouse model to study the consequences of the condensin II deficiency on cell cycle regulation in several different hematopoietic lineages. The Caph2nes/nes mice are viable and fertile, with no obvious abnormalities other than the thymus, which is drastically reduced in size. Previous studies reported greater than a hundred-fold reduction in the number of CD4+ CD8+ thymocytes. I set out to understand why the alteration of a ubiquitously expressed protein which functions in a fundamental cellular process would result in such a cell-type specific block in development. To achieve this, I investigated the possibility that condensin II is involved in interphase processes as well as in mitosis. In addition, I studied the aspects of T cell development that may make this lineage particularly vulnerable to condensin II deficiency. Finally, I carried out a preliminary investigation into the biochemical properties of the condensin complexes. During my PhD., I found strong evidence to suggest that the Caph2nes/nes T cell-specific phenotype arises due to abnormal cell division. However, I was unable to find any evidence to support the hypothesis that the phenotype is a consequence of abnormal interphase processes. Upon systematic analysis of several stages of hematopoietic differentiation, I found that at a specific stage of T cell development, the mutation results in an increased proportion of cells with abnormal ploidy, followed by a drastic reduction in cell numbers. Erythroid cells revealed a similar increase in the frequency of hyperdiploid cells, but no reduction in cell numbers. B cells and hematopoietic precursors did not reveal an increase in hyperdiploidy, or a reduction in cell numbers in wildtype relative to mutant. Subsequently, I found preliminary evidence to suggest that the T cell-specificity may be due to more rapid progression of CD4+ CD8+ T cells from S phase to M phase, relative to other hematopoietic stages. Finally, a preliminary investigation into the biochemical properties of the condensin complex revealed apparent imbalances in the expression of condensin subunits in T, B and erythroid cells. The sedimentation profile of CAP-H2 from whole-thymus extract did not exclude the possibility that condensin subunits might be forming heavier-weight complexes with non-SMC proteins. Further work must be carried out to determine whether this sedimentation pattern is unique to T cells.
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Dadon, Daniel Benjamin. « 3D chromosome structure and chromatin proteomics ». Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104174.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Biology, 2016.
Cataloged from PDF version of thesis. "May 2016."
Includes bibliographical references.
The selective interpretation of the genome through transcription enables the production of every cell type's distinct gene expression program from a common genome. Transcription takes place within, and is controlled by, highly organized three-dimensional (3D) chromosome structures. The first part of the work presented here describes the generation of 3D chromosome regulatory landscape maps of human naive and primed embryonic stem cells. To create these 3D chromosome regulatory landscape maps, genome-wide enhancer and insulator locations were mapped and then placed into a 3D interaction framework formed by cohesin-mediated 3D chromosome structures. Enhancer (H3K27ac) and insulator (CTCF) locations were mapped using ChIP-sequencing, whereas 3D chromosome structures were detected by cohesin-ChIA-PET. 3D chromosome structures connecting insulators (CTCF-CTCF loops) were shown to form topologically associating domains (TADs) and insulated neighborhoods, which were mostly preserved in the transition between naive and primed states. Insulated neighborhoods are critical for proper gene expression, and their disruption leads to the improper regulation of local gene expression. Changes in enhancer-promoter loops occurred within preserved insulated neighborhoods during cell state transition. The CTCF anchors of CTCF-CTCF loops are conserved across species and are frequently mutated in cancer cells. These 3D chromosome regulatory landscapes provide a foundation for the future investigation of the relationship between chromosome structure and gene control in human development and disease. The work presented in the second part focuses on developing an approach called "chromatin proteomic profiling" to identify protein factors associated with various active and repressed portions of the genome marked by specific histone modifications. The histone modifications assayed by chromatin proteomic profiling are associated with genomic regions where specific transcriptional activities occur, thus implicating the identified proteins in these activities. This chromatin proteomic profiling study revealed a catalog of known, implicated, and novel proteins associated with these functionally characterized genomic regions.
by Daniel Benjamin Dadon.
Ph. D.
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Croft, Jenny Anne. « Correlating mammalian chromosome structure and function ». Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/13491.

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The euchromatin of mammalian chromosomes is broadly divided into two types with opposing characteristics: G-bands are revealed by Giemsa staining. These bands are generally late replicating, T-rich, low in gene density and appear to have a "closed" chromatin structure. R-bands are revealed by reverse Giemsa staining. These bands are generally early replicating, GC-rich, high in gene density and appear to have a more "open" chromatin structure. These two band types are intercalated throughout the mammalian genome making comparative studies of their behaviour difficult. However, in the human genome, chromosome 18 predominantly displays the features of G-bands and chromosome 19 generally displays the features of R-bands. These chromosomes were shown to be comparable in DNA content and size at metaphase and are, thus, ideal to investigate further the apparent links between chromosome structure and function. Some models of chromosome structure suggest differences in the higher order packaging of the different band types of metaphase chromosomes. Any differences should be reflected in the overall structure of chromosomes 18 and 19. Combining fluorescence in situ hybridisation and biochemical extraction of metaphase chromosomes, I detected no significant differences in their structure. In contrast, the two chromosomes demonstrated different structural characteristics in the interphase nucleus. I found that chromosome 18 occupies a relatively condensed territory, close to the periphery of the nucleus, while chromosome 19 occupies a considerably larger territory, more centrally located. My studies of different cell types and on cells at different stages of the cell cycle suggest that these characteristics generally apply in human cells, but not in a somatic cell hybrid background. Analysis of nuclei with a reciprocal 18:19 translocation showed that the translocated segments were orientated towards the positions occupied by their structurally normal homologues. The size but not the positioning of an interphase territory appears to be dependent on transcriptional activity.
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Almuhur, Rana Ahmad Suleiman. « Integrating chromatin structure and global chromosome dynamics ». Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5573/.

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DNA associates with proteins to form chromatin which is essential for the compaction of the DNA into the cell nucleus and is highly dynamic in order to allow the different biological processes of the DNA to occur. Chromatin compaction is achieved at different hierarchical levels: the 10nm fibre (DNA associates to nucleosomes formed by different histones), the Higher Order Chromatin fibre and the 300 nm chromosome structures. This study has shown that both H1 and H4 histones play a crucial role in preserving meiotic as well as mitotic chromosome structure and functional genome integrity in Arabidopsis. The role of the different linker histone H1 isoforms as well as the core histone H4 in Arabidopsis thaliana was investigated using T-DNA and RNAi mutant lines which showed different meiotic defects. Chromosomal breaks as well as non-homologous connections in the h4RNAi were linked to 45S/5S rDNA disorganisation, suggesting that H4 preserves chromosome integrity at these rDNA regions. Ath1.1 mutant presented univalents and reduced chiasma frequency at metaphase I, linked to a severe defect in ASY1 localisation on the meiotic chromosome axes. Thus, indicating that histone H1.1 is vital for proper chromatin axis organization that permit normal loading of recombination machinery proteins in Arabidopsis.
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Gilbert, Sandra L. (Sandra Leigh) 1968. « Chromatin structure of the inactive X chromosome ». Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85344.

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Ross, Brian Christopher. « Computational tools for modeling and measuring chromosome structure ». Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79262.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 99-112).
DNA conformation within cells has many important biological implications, but there are challenges both in modeling DNA due to the need for specialized techniques, and experimentally since tracing out in vivo conformations is currently impossible. This thesis contributes two computational projects to these efforts. The first project is a set of online and offline calculators of conformational statistics using a variety of published and unpublished methods, addressing the current lack of DNA model-building tools intended for general use. The second project is a reconstructive analysis that could enable in vivo mapping of DNA conformation at high resolution with current experimental technology.
by Brian Christopher Ross.
Ph.D.
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Horsley, Sharon Wendy. « Characterisation of chromosome 16 rearrangements in patients with alpha thalassaemia ». Thesis, Oxford Brookes University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325201.

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Livres sur le sujet "Structure du chromosome"

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Gustafson, J. Perry, et R. Appels, dir. Chromosome Structure and Function. Boston, MA : Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-1037-2.

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Bhat, Tariq Ahmad, et Aijaz Ahmad Wani, dir. Chromosome Structure and Aberrations. New Delhi : Springer India, 2017. http://dx.doi.org/10.1007/978-81-322-3673-3.

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Houben, Andreas. Chromosome structure and function. Basel : Karger, 2009.

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4

S, Risley Michael, dir. Chromosome structure and function. New York : Van Nostrand Reinhold Co., 1986.

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Mitchell, Eddy E., Griswold Michael D, New York Academy of Sciences et North American Testis Workshop (19th : 2007 : Tampa, Fla.), dir. Testicular chromosome structure and gene expression. Malden, MA : Published on behalf of the New York Academy of Sciences by Blackwell Pub., 2007.

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Therman, Eeva. Human chromosomes : Structure, behavior, effects. 2e éd. New York : Springer-Verlag, 1985.

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7

Sobit, R. C., G. Obe et R. S. Athwal, dir. Some Aspects of Chromosome Structure and Functions. Dordrecht : Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0334-6.

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C, Sobti R., Obe G et Athwal R. S, dir. Some aspects of chromosome structure and functions. Boston : Kluwer Academic Publishers, 2002.

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Stadler Genetics Symposium (18th 1987 University of Missouri--Columbia). Chromosome structure and function : Impact of new concepts. New York : Plenum Press, 1988.

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1924-, Smith George F., et National Down Syndrome Society (U.S.). Symposium, dir. Molecular structure of the number 21 chromosome and Down syndrome. New York, N.Y : New York Academy of Sciences, 1985.

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Chapitres de livres sur le sujet "Structure du chromosome"

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Pettijohn, D. E. « Bacterial Chromosome Structure ». Dans Nucleic Acids and Molecular Biology, 152–62. Berlin, Heidelberg : Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-84150-7_9.

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Appels, Rudi, Rosalind Morris, Bikram S. Gill et Cedric E. May. « Variable Structure and Folding of DNA ». Dans Chromosome Biology, 244–69. Boston, MA : Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-5409-7_17.

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Shakoori, Abdul Rauf. « Introduction to Chromosome ». Dans Chromosome Structure and Aberrations, 1–11. New Delhi : Springer India, 2017. http://dx.doi.org/10.1007/978-81-322-3673-3_1.

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Appels, Rudi, Rosalind Morris, Bikram S. Gill et Cedric E. May. « A Historical Perspective on Chromosome Structure, Function, and Behavior ». Dans Chromosome Biology, 7–21. Boston, MA : Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-5409-7_2.

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Elgin, S. C. R., S. A. Amero, J. C. Eissenberg, G. Fleischmann, D. S. Gilmour et T. C. James. « Distribution Patterns of Nonhistone Chromosomal Proteins on Polytene Chromosomes : Functional Correlations ». Dans Chromosome Structure and Function, 145–56. Boston, MA : Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-1037-2_6.

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Brenner, David J., John F. Ward et Rainer K. Sachs. « Track Structure, Chromosome Geometry and Chromosome Aberrations ». Dans Computational Approaches in Molecular Radiation Biology, 93–113. Boston, MA : Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9788-6_8.

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Geszvain, Kati, et Robert Landick. « The Structure of Bacterial RNA Polymerase ». Dans The Bacterial Chromosome, 283–96. Washington, DC, USA : ASM Press, 2014. http://dx.doi.org/10.1128/9781555817640.ch15.

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Douglas, Ryan N., et James A. Birchler. « B Chromosomes ». Dans Chromosome Structure and Aberrations, 13–39. New Delhi : Springer India, 2017. http://dx.doi.org/10.1007/978-81-322-3673-3_2.

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Flavell, R. B., M. D. Bennett, A. G. Seal et J. Hutchinson. « Chromosome structure and organization ». Dans Wheat Breeding, 211–68. Dordrecht : Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3131-2_8.

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Oliveira, Claudio, Jonathan M. Wright et Fausto Foresti. « Chromosome Structure in Fishes ». Dans Some Aspects of Chromosome Structure and Functions, 103–8. Dordrecht : Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-010-0334-6_10.

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Actes de conférences sur le sujet "Structure du chromosome"

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« Chromosome evolution in Ruminantia ». Dans Bioinformatics of Genome Regulation and Structure/Systems Biology (BGRS/SB-2022) :. Institute of Cytology and Genetics, the Siberian Branch of the Russian Academy of Sciences, 2022. http://dx.doi.org/10.18699/sbb-2022-087.

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« X-chromosome Inactivation in American Mink iPSCs ». Dans Bioinformatics of Genome Regulation and Structure/ Systems Biology. institute of cytology and genetics siberian branch of the russian academy of science, Novosibirsk State University, 2020. http://dx.doi.org/10.18699/bgrs/sb-2020-310.

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de Grooth, Bart G., Constant A. Putman, Kees O. van der Werf, Niko F. van Hulst, Geeske van Oort et Jan Greve. « Chromosome structure investigated with the atomic-force microscope ». Dans OE/LASE '92, sous la direction de Srinivas Manne. SPIE, 1992. http://dx.doi.org/10.1117/12.58188.

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Sukjit, P., et H. Unger. « Chromosome-Controlled Structure Building in Decentralized Computer Systems ». Dans Modelling, Identification, and Control. Calgary,AB,Canada : ACTAPRESS, 2010. http://dx.doi.org/10.2316/p.2010.702-077.

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« Analysis of chromosome structure in Musaceae using oligo painting ». Dans Plant Genetics, Genomics, Bioinformatics, and Biotechnology. Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, 2019. http://dx.doi.org/10.18699/plantgen2019-172.

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Kozyreva, S. Yu, M. M. Gridina, A. A. Torgasheva, V. S. Fishman, K. S. Zadesenets et L. P. Malinovskaya. « DISSECTING THE STRUCTURE OF THE CHROMOSOMAL REARRANGEMENTS IN CHROMOSOME 1A IN GREAT TITS (PARUS MAJOR) USING HI-C TECHNIQUE ». Dans OpenBio-2023. ИПЦ НГУ, 2023. http://dx.doi.org/10.25205/978-5-4437-1526-1-21.

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Polymorphism caused by complex rearrangement on chromosome 1A has been identified in the population of the Great Tit (Parus major). Сhromosomal rearrangement involves large inversion and regions with copy number variations, potentially spanning around 3.5 Mb. Using Hi-C technique we determined the inversion breakpoints with an accuracy of 1000 bp and developed an approach that allowed to discover additional 15 Mb of genomic sequences in the rearranged chromosome.
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« Chromosome synapsis and recombination in intraspecific and interspecific heterozygotes for chromosomal rearrangements in voles of the genus Alexandromys ». Dans Bioinformatics of Genome Regulation and Structure/Systems Biology (BGRS/SB-2022) :. Institute of Cytology and Genetics, the Siberian Branch of the Russian Academy of Sciences, 2022. http://dx.doi.org/10.18699/sbb-2022-384.

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« Composition of sex chromosomes of veiled chameleon (Chamaeleo calyptratus, Iguania, Squamata) reveals new insights into sex chromosome evolution of iguanian lizards ». Dans Bioinformatics of Genome Regulation and Structure/Systems Biology (BGRS/SB-2022) :. Institute of Cytology and Genetics, the Siberian Branch of the Russian Academy of Sciences, 2022. http://dx.doi.org/10.18699/sbb-2022-097.

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Aliefa, Marwa Hasna, et Suyanto Suyanto. « Variable-Length Chromosome for Optimizing the Structure of Recurrent Neural Network ». Dans 2020 International Conference on Data Science and Its Applications (ICoDSA). IEEE, 2020. http://dx.doi.org/10.1109/icodsa50139.2020.9213012.

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« Different approaches to chromosome rearrangement detection in the model cell line ». Dans Bioinformatics of Genome Regulation and Structure/Systems Biology (BGRS/SB-2022) :. Institute of Cytology and Genetics, the Siberian Branch of the Russian Academy of Sciences, 2022. http://dx.doi.org/10.18699/sbb-2022-078.

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Rapports d'organisations sur le sujet "Structure du chromosome"

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Rill, R. The impact of energy related pollutants on chromosome structure. Office of Scientific and Technical Information (OSTI), octobre 1989. http://dx.doi.org/10.2172/5345926.

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Shapiro, Daniel Benjamin. Polarized light scattering as a probe for changes in chromosome structure. Office of Scientific and Technical Information (OSTI), octobre 1993. http://dx.doi.org/10.2172/10107208.

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Breiman, Adina, Jan Dvorak, Abraham Korol et Eduard Akhunov. Population Genomics and Association Mapping of Disease Resistance Genes in Israeli Populations of Wild Relatives of Wheat, Triticum dicoccoides and Aegilops speltoides. United States Department of Agriculture, décembre 2011. http://dx.doi.org/10.32747/2011.7697121.bard.

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Wheat is the most widely grown crop on earth, together with rice it is second to maize in total global tonnage. One of the emerging threats to wheat is stripe (yellow) rust, especially in North Africa, West and Central Asia and North America. The most efficient way to control plant diseases is to introduce disease resistant genes. However, the pathogens can overcome rapidly the effectiveness of these genes when they are wildly used. Therefore, there is a constant need to find new resistance genes to replace the non-effective genes. The resistance gene pool in the cultivated wheat is depleted and there is a need to find new genes in the wild relative of wheat. Wild emmer (Triticum dicoccoides) the progenitor of the cultivated wheat can serve as valuable gene pool for breeding for disease resistance. Transferring of novel genes into elite cultivars is highly facilitated by the availability of information of their chromosomal location. Therefore, our goals in this study was to find stripe rust resistant and susceptible genotypes in Israeli T. dicoccoides population, genotype them using state of the art genotyping methods and to find association between genetic markers and stripe rust resistance. We have screened 129 accessions from our collection of wild emmer wheat for resistance to three isolates of stripe rust. About 30% of the accessions were resistant to one or more isolates, 50% susceptible, and the rest displayed intermediate response. The accessions were genotyped with Illumina'sInfinium assay which consists of 9K single nucleotide polymorphism (SNP) markers. About 13% (1179) of the SNPs were polymorphic in the wild emmer population. Cluster analysis based on SNP diversity has shown that there are two main groups in the wild population. A big cluster probably belongs to the Horanum ssp. and a small cluster of the Judaicum ssp. In order to avoid population structure bias, the Judaicum spp. was removed from the association analysis. In the remaining group of genotypes, linkage disequilibrium (LD) measured along the chromosomes decayed rapidly within one centimorgan. This is the first time when such analysis is conducted on a genome wide level in wild emmer. Such a rapid decay in LD level, quite unexpected for a selfer, was not observed in cultivated wheat collection. It indicates that wild emmer populations are highly suitable for association studies yielding a better resolution than association studies in cultivated wheat or genetic mapping in bi-parental populations. Significant association was found between an SNP marker located in the distal region of chromosome arm 1BL and resistance to one of the isolates. This region is not known in the literature to bear a stripe rust resistance gene. Therefore, there may be a new stripe rust resistance gene in this locus. With the current fast increase of wheat genome sequence data, genome wide association analysis becomes a feasible task and efficient strategy for searching novel genes in wild emmer wheat. In this study, we have shown that the wild emmer gene pool is a valuable source for new stripe rust resistance genes that can protect the cultivated wheat.
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Pawlowski, Wojtek P., et Avraham A. Levy. What shapes the crossover landscape in maize and wheat and how can we modify it. United States Department of Agriculture, janvier 2015. http://dx.doi.org/10.32747/2015.7600025.bard.

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Meiotic recombination is a process in which homologous chromosomes engage in the exchange of DNA segments, creating gametes with new genetic makeup and progeny with new traits. The genetic diversity generated in this way is the main engine of crop improvement in sexually reproducing plants. Understanding regulation of this process, particularly the regulation of the rate and location of recombination events, and devising ways of modifying them, was the major motivation of this project. The project was carried out in maize and wheat, two leading crops, in which any advance in the breeder’s toolbox can have a huge impact on food production. Preliminary work done in the USA and Israeli labs had established a strong basis to address these questions. The USA lab pioneered the ability to map sites where recombination is initiated via the induction of double-strand breaks in chromosomal DNA. It has a long experience in cytological analysis of meiosis. The Israeli lab has expertise in high resolution mapping of crossover sites and has done pioneering work on the importance of epigenetic modifications for crossover distribution. It has identified genes that limit the rates of recombination. Our working hypothesis was that an integrative analysis of double-strand breaks, crossovers, and epigenetic data will increase our understanding of how meiotic recombination is regulated and will enhance our ability to manipulate it. The specific objectives of the project were: To analyze the connection between double-strand breaks, crossover, and epigenetic marks in maize and wheat. Protocols developed for double-strand breaks mapping in maize were applied to wheat. A detailed analysis of existing and new data in maize was conducted to map crossovers at high resolution and search for DNA sequence motifs underlying crossover hotspots. Epigenetic modifications along maize chromosomes were analyzed as well. Finally, a computational analysis tested various hypotheses on the importance of chromatin structure and specific epigenetic modifications in determining the locations of double-strand breaks and crossovers along chromosomes. Transient knockdowns of meiotic genes that suppress homologous recombination were carried out in wheat using Virus-Induced Gene Silencing. The target genes were orthologs of FANCM, DDM1, MET1, RECQ4, and XRCC2.
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Medrano, Juan, Adam Friedmann, Moshe (Morris) Soller, Ehud Lipkin et Abraham Korol. High resolution linkage disequilibrium mapping of QTL affecting milk production traits in Israel Holstein dairy cattle. United States Department of Agriculture, mars 2008. http://dx.doi.org/10.32747/2008.7696509.bard.

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Original objectives: To create BAC contigs covering two QTL containing chromosomal regions (QTLR) and obtain BAC end sequence information as a platform for SNP identification. Use the SNPs to search for marker-QTL linkage disequilibrium (LD) in the test populations (US and Israel Holstein cattle). Identify candidate genes, test for association with dairy cattle production and functional traits, and confirm any associations in a secondary test population. Revisions in the course of the project: The selective recombinant genotyping (SRG) methodology which we implemented to provide moderate resolution QTL mapping turned out to be less effective than expected, due to problems introduced by incomplete marker informativity. This required a no-cost one-year extension of the project. Aside from this, the project was implemented essentially as envisaged, but only with respect to a single QTLR and single population association-test. Background to the topic. Dairy cattle breeders are looking to marker-assisted selection (MAS) as a means of identifying genetically superior sires and dams. MAS based on population-wide LD can be many times more effective than MAS based on within-family linkage mapping. In this proposal we developed a protocol leading from family based QTL mapping to population-wide LD between markers and the QTL Major conclusions, solutions, achievements. The critical importance of marker informativity for application of the SRG design in outcrossing random mating populations was identified, and an alternative Fractioned Pool Design (FPD) based on selective DNA pooling was developed. We demonstrated the feasibility of constructing a BAC contig across a targeted chromosomal region flanking the marker RM188 on bovine chromosome BTA4, which was shown in previous work to contain a QTL affecting milk production traits. BAC end sequences were obtained and successfully screened for SNPs. LD studies of these SNPs in the Israel population, and of an independent set of SNPs taken across the entire proximal region of BTA4 in the USA population, showed a much lower degree of LD than previously reported in the literature. Only at distances in the sub-cM level did an appreciable fraction of SNP marker-pairs show levels of LD useful for MAS. In contrast, studies in the Israel population using microsatellite markers, presented an equivalent degree of LD at a 1-5 separation distance. SNP LD appeared to reflect historical population size of Bostaurus (Ne=5000- 10,000), while microsatellite LD appeared to be in proportion to more recent effective population size of the Holstein breed (Ne=50-100). An appreciable fraction of the observed LD was due to Family admixture structure of the Holstein population. The SNPs MEOX2/IF2G (found within the gene SETMAR at 23,000 bp from RM188) and SNP23 were significantly associated with PTA protein, Cheese dollars and Net Merit Protein in the Davis bull resource population, and were also associated with protein and casein percentages in the Davis cow resource population. Implications. These studies document a major difference in degree of LD presented by SNPs as compared to microsatellites, and raise questions as to the source of this difference and its implications for QTL mapping and MAS. The study lends significant support to the targeted approach to fine map a previously identified QTL. Using high density genotyping with SNP discovered in flanking genes to the QTL, we have identified important markers associated with milk protein percentage that can be tested in markers assisted selection programs.
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Fallik, Elazar, Robert Joly, Ilan Paran et Matthew A. Jenks. Study of the Physiological, Molecular and Genetic Factors Associated with Postharvest Water Loss in Pepper Fruit. United States Department of Agriculture, décembre 2012. http://dx.doi.org/10.32747/2012.7593392.bard.

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The fruit of pepper (Capsicum annuum) commonly wilts (or shrivels) during postharvest storage due to rapid water loss, a condition that greatly reduces its shelf life and market value. The fact that pepper fruit are hollow, and thus have limited water content, only exacerbates this problem in pepper. The collaborators on this project completed research whose findings provided new insight into the genetic, physiological, and biochemical basis for water loss from the fruits of pepper (Capsicum annuum and related Capsicum species). Well-defined genetic populations of pepper were used in this study, the first being a series of backcross F₁ and segregating F₂, F₃, and F₄ populations derived from two original parents selected for having dramatic differences in fruit water loss rate (very high and very low water loss). The secondly population utilized in these studies was a collection of 50 accessions representing world diversity in both species and cultivar types. We found that an unexpectedly large amount of variation was present in both fruit wax and cutin composition in these collections. In addition, our studies revealed significant correlations between the chemical composition of both the fruit cuticular waxes and cutin monomers with fruit water loss rate. Among the most significant were that high alkane content in fruit waxes conferred low fruit water loss rates and low permeability in fruit cuticles. In contrast, high amounts of terpenoids (plus steroidal compounds) were associated with very high fruit water loss and cuticle permeability. These results are consistent with our models that the simple straight chain alkanes pack closely together in the cuticle membrane and obstruct water diffusion, whereas lipids with more complex 3-dimensional structure (such as terpenoids) do not pack so closely, and thus increase the diffusion pathways. The backcross segregating populations were used to map quantitative trait loci (QTLs) associated with water loss (using DART markers, Diversity Arrays Technology LTD). These studies resulted in identification of two linked QTLs on pepper’s chromosome 10. Although the exact genetic or physiological basis for these QTLs function in water loss is unknown, the genotypic contribution in studies of near-isogenic lines selected from these backcross populations reveals a strong association between certain wax compounds, the free fatty acids and iso-alkanes. There was also a lesser association between the water loss QTLs with both fruit firmness and total soluble sugars. Results of these analyses have revealed especially strong genetic linkages between fruit water loss, cuticle composition, and two QTLs on chromosome 10. These findings lead us to further speculate that genes located at or near these QTLs have a strong influence on cuticle lipids that impact water loss rate (and possibly, whether directly or indirectly, other traits like fruit firmness and sugar content). The QTL markers identified in these studies will be valuable in the breeding programs of scientists seeking to select for low water loss, long lasting fruits, of pepper, and likely the fruits of related commodities. Further work with these newly developed genetic resources should ultimately lead to the discovery of the genes controlling these fruit characteristics, allowing for the use of transgenic breeding approaches toward the improvement of fruit postharvest shelf life.
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Glesne, D., E. Huberman, F. Collart, T. Varkony et H. Drabkin. Chromosomal localization and structure of the human type II IMP dehydrogenase gene. Office of Scientific and Technical Information (OSTI), mai 1994. http://dx.doi.org/10.2172/10148872.

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Bradbury, E. M. Structural studies of chromatin and chromosomes. Progress report, March 15--September 15, 1997. Office of Scientific and Technical Information (OSTI), novembre 1997. http://dx.doi.org/10.2172/548675.

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Rill, R. L. The impact of energy related pollutants on chromosome structures. Final performance report, May 1, 1987--April 30, 1992. Office of Scientific and Technical Information (OSTI), mars 1998. http://dx.doi.org/10.2172/607511.

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Manulis-Sasson, Shulamit, Christine D. Smart, Isaac Barash, Laura Chalupowicz, Guido Sessa et Thomas J. Burr. Clavibacter michiganensis subsp. michiganensis-tomato interactions : expression and function of virulence factors, plant defense responses and pathogen movement. United States Department of Agriculture, février 2015. http://dx.doi.org/10.32747/2015.7594405.bard.

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Clavibactermichiganensissubsp. michiganensis(Cmm), the causal agent of bacterial wilt and canker of tomato, is the most destructive bacterial disease of tomato causing substantial economic losses in Israel, the U.S.A. and worldwide. The goal of the project was to unravel the molecular strategies that allow Cmm, a Gram-positive bacterium, to develop a successful infection in tomato. The genome of Cmm contains numerous genes encoding for extracellular serine proteases and cell wall degrading enzymes. The first objective was to elucidate the role of secreted serine proteases in Cmm virulence. Mutants of nine genes encoding serine proteases of 3 different families were tested for their ability to induce wilting, when tomato stems were puncture-inoculated, as compared to blisters formation on leaves, when plants were spray-inoculated. All the mutants showed reduction in wilting and blister formation as compared to the wild type. The chpCmutant displayed the highest reduction, implicating its major role in symptom development. Five mutants of cell wall degrading enzymes and additional genes (i.e. perforin and sortase) caused wilting but were impaired in their ability to form blisters on leaves. These results suggest that Cmm differentially expressed virulence genes according to the site of penetration. Furthermore, we isolated and characterized two Cmmtranscriptional activators, Vatr1 and Vatr2 that regulate the expression of virulence factors, membrane and secreted proteins. The second objective was to determine the effect of bacterial virulence genes on movement of Cmm in tomato plants and identify the routes by which the pathogen contaminates seeds. Using a GFP-labeledCmm we could demonstrate that Cmm extensively colonizes the lumen of xylem vessels and preferentially attaches to spiral secondary wall thickening of the protoxylem and formed biofilm-like structures composed of large bacterial aggregates. Our findings suggest that virulence factors located on the chp/tomAPAI or the plasmids are required for effective movement of the pathogen in tomato and for the formation of cellular aggregates. We constructed a transposon plasmid that can be stably integrated into Cmm chromosome and express GFP, in order to follow movement to the seeds. Field strains from New York that were stably transformed with this construct, could not only access seeds systemically through the xylem, but also externally through tomato fruit lesions, which harbored high intra-and intercellular populations. Active movement and expansion of bacteria into the fruit mesocarp and nearby xylem vessels followed, once the fruit began to ripen. These results highlight the ability of Cmm to invade tomato fruit and seed through multiple entry routes. The third objective was to assess correlation between disease severity and expression levels of Cmm virulence genes and tomato defense genes. The effect of plant age on expression of tomato defense related proteins during Cmm infection was analyzed by qRT-PCR. Five genes out of eleven showed high induction at early stages of infection of plants with 19/20 leaves compared to young plants bearing 7/8 leaves. Previous results showed that Cmm virulence genes were expressed at early stages of infection in young plants compared to older plants. Results of this study suggest that Cmm virulence genes may suppress expression of tomato defense-related genes in young plants allowing effective disease development. The possibility that chpCis involved in suppression of tomato defense genes is currently under investigation by measuring the transcript level of several PR proteins, detected previously in our proteomics study. The fourth objective was to define genome location and stability of virulence genes in Cmm strains. New York isolates were compared to Israeli, Serbian, and NCPPB382 strains. The plasmid profiles of New York isolates were diverse and differed from both Israeli and Serbian strains. PCR analysis indicated that the presence of putative pathogenicity genes varied between isolates and highlighted the ephemeral nature of pathogenicity genes in field populations of Cmm. Results of this project significantly contributed to the understanding of Cmm virulence, its movement within tomato xylem or externally into the seeds, the role of serine proteases in disease development and initiated research on global regulation of Cmm virulence. These results form a basis for developing new strategies to combat wilt and canker disease of tomato.
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