Relevant bibliographies by topics / Structure des chromosomes

Academic literature on the topic 'Structure des chromosomes'

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Published: 4 April 2023

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Journal articles on the topic "Structure des chromosomes"

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Gasser, Susan M. "Chromosome Structure: Coiling up chromosomes." Current Biology 5, no. 4 (April 1995): 357–60. http://dx.doi.org/10.1016/s0960-9822(95)00071-6.

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Liehr, Thomas. "From Human Cytogenetics to Human Chromosomics." International Journal of Molecular Sciences 20, no. 4 (February 14, 2019): 826. http://dx.doi.org/10.3390/ijms20040826.

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Background: The concept of “chromosomics” was introduced by Prof. Uwe Claussen in 2005. Herein, the growing insights into human chromosome structure finally lead to a “chromosomic view” of the three-dimensional constitution and plasticity of genes in interphase nuclei are discussed. This review is dedicated to the memory of Prof. Uwe Claussen (30 April 1945–20 July 2008). Recent findings: Chromosomics is the study of chromosomes, their three-dimensional positioning in the interphase nucleus, the consequences from plasticity of chromosomal subregions and gene interactions, the influence of chromatin-modification-mediated events on cells, and even individuals, evolution, and disease. Progress achieved in recent years is summarized, including the detection of chromosome-chromosome-interactions which, if damaged, lead to malfunction and disease. However, chromosomics in the Human Genetics field is not progressing presently, as research interest has shifted from single cell to high throughput, genomic approaches. Conclusion: Chromosomics and its impact were predicted correctly in 2005 by Prof. Claussen. Although some progress was achieved, present reconsiderations of the role of the chromosome and the single cell in Human Genetic research are urgently necessary.
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Anderson, Lorinda K., Naser Salameh, Hank W. Bass, Lisa C. Harper, W. Z. Cande, Gerd Weber, and Stephen M. Stack. "Integrating Genetic Linkage Maps With Pachytene Chromosome Structure in Maize." Genetics 166, no. 4 (April 1, 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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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 (August 15, 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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Pizzaia, Daniel, Vanessa M. Oliveira-Maekawa, Aline R. Martins, Mateus Mondin, and Margarida L. R. Aguiar-Perecin. "Karyotype structure and NOR activity in Brazilian Smilax Linnaeus, 1753 species (Smilacaceae)." Comparative Cytogenetics 13, no. 3 (August 22, 2019): 245–63. http://dx.doi.org/10.3897/compcytogen.v13i3.35775.

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The genus Smilax Linnaeus, 1753 (Smilacaceae) is a large genus of dioecious plants distributed in tropical, subtropical and temperate regions. Some Smilax species have medicinal importance and their identification is important for the control of raw material used in the manufacture of phytotherapeutical products. The karyotypes of seven Brazilian Smilax species were investigated. Mitotic metaphases of roots from young plants were analysed in Feulgen-stained preparations. The karyotypes were asymmetric and modal with 2n = 2x = 32 chromosomes gradually decreasing in size. In S. goyazana A De Candolle & C De Candolle, 1878, a polyploid species, 2n = 4x = 64. In all the species, the large and medium-sized chromosomes were subtelocentric and submetacentric and the small chromosomes were submetacentric or metacentric. Their karyotypes were quite similar, with differences in the arm ratio of some chromosomes. S. fluminensis Steudel, 1841 differed from the other species by having a large metacentric chromosome 1. These findings suggest that evolution occurred without drastic changes in the chromosomal structure in the species analyzed. Terminal secondary constrictions were visualized on the short arm of some chromosomes, but they were detected only in one homologue of each pair. Due to the terminal location and the degree of chromosome condensation, secondary constrictions were not visualized in some species. The nucleolus organizer regions (NORs) were mapped by silver-staining and fluorescent in situ hybridization (FISH) in S. rufescens Grisebach, 1842 and S. fluminensis. Silver-staining and FISH signals were colocalized on the short arms of six chromosomes in S. rufescens and four chromosomes in S. fluminensis. In FISH preparations, one of the largest chromosomes had the secondary constrictions highly decondensed in some cells. This finding and the heteromorphism observed in Feulgen-stained chromosomes suggest that differential rRNA gene expression between homologous rDNA loci can occur in some cells, resulting in different degrees of ribosomal chromatin decondensation. The presence of a heteromorphic chromosome pair in S. rufescens, S. polyantha Grisebach, 1842 and S. goyazana suggests a chromosomal sex determination in these dioecious species.
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Sajid, Atiqa, El-Nasir Lalani, Bo Chen, Teruo Hashimoto, Darren K. Griffin, Archana Bhartiya, George Thompson, Ian K. Robinson, and Mohammed Yusuf. "Ultra-Structural Imaging Provides 3D Organization of 46 Chromosomes of a Human Lymphocyte Prophase Nucleus." International Journal of Molecular Sciences 22, no. 11 (June 1, 2021): 5987. http://dx.doi.org/10.3390/ijms22115987.

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Three dimensional (3D) ultra-structural imaging is an important tool for unraveling the organizational structure of individual chromosomes at various stages of the cell cycle. Performing hitherto uninvestigated ultra-structural analysis of the human genome at prophase, we used serial block-face scanning electron microscopy (SBFSEM) to understand chromosomal architectural organization within 3D nuclear space. Acquired images allowed us to segment, reconstruct, and extract quantitative 3D structural information about the prophase nucleus and the preserved, intact individual chromosomes within it. Our data demonstrate that each chromosome can be identified with its homolog and classified into respective cytogenetic groups. Thereby, we present the first 3D karyotype built from the compact axial structure seen on the core of all prophase chromosomes. The chromosomes display parallel-aligned sister chromatids with familiar chromosome morphologies with no crossovers. Furthermore, the spatial positions of all 46 chromosomes revealed a pattern showing a gene density-based correlation and a neighborhood map of individual chromosomes based on their relative spatial positioning. A comprehensive picture of 3D chromosomal organization at the nanometer level in a single human lymphocyte cell is presented.
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Howe, Mary, Kent L. McDonald, Donna G. Albertson, and Barbara J. Meyer. "Him-10 Is Required for Kinetochore Structure and Function on Caenorhabditis elegans Holocentric Chromosomes." Journal of Cell Biology 153, no. 6 (June 11, 2001): 1227–38. http://dx.doi.org/10.1083/jcb.153.6.1227.

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Macromolecular structures called kinetochores attach and move chromosomes within the spindle during chromosome segregation. Using electron microscopy, we identified a structure on the holocentric mitotic and meiotic chromosomes of Caenorhabditis elegans that resembles the mammalian kinetochore. This structure faces the poles on mitotic chromosomes but encircles meiotic chromosomes. Worm kinetochores require the evolutionarily conserved HIM-10 protein for their structure and function. HIM-10 localizes to the kinetochores and mediates attachment of chromosomes to the spindle. Depletion of HIM-10 disrupts kinetochore structure, causes a failure of bipolar spindle attachment, and results in chromosome nondisjunction. HIM-10 is related to the Nuf2 kinetochore proteins conserved from yeast to humans. Thus, the extended kinetochores characteristic of C. elegans holocentric chromosomes provide a guide to the structure, molecular architecture, and function of conventional kinetochores.
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Spell, R. M., and C. Holm. "Nature and distribution of chromosomal intertwinings in Saccharomyces cerevisiae." Molecular and Cellular Biology 14, no. 2 (February 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., and C. Holm. "Nature and distribution of chromosomal intertwinings in Saccharomyces cerevisiae." Molecular and Cellular Biology 14, no. 2 (February 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, and Haruyasu Kinashi. "Circularized Chromosome with a Large Palindromic Structure in Streptomyces griseus Mutants." Journal of Bacteriology 186, no. 11 (June 1, 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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Dissertations / Theses on the topic "Structure des chromosomes"

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Sun, Lawrence (Lawrence J. ). "Inference of 3D structure of diploid chromosomes." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119570.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 61-62).
The spatial organization of DNA in the cell nucleus plays an important role for gene regulation, DNA replication, and genomic integrity. Through the development of chromosome capture experiments (such as 3C, 4C, Hi-C) it is now possible to obtain the contact frequencies of the DNA at the whole-genome level. In this thesis, we study the problem of reconstructing the 3D organization of the genome from whole-genome contact frequencies. A standard approach is to transform the contact frequencies into noisy distance measurements and then apply semidefinite programming (SDP) formulations to obtain the 3D configurations. However, neglected in such reconstructions is the fact that most eukaryotes including humans are diploid and therefore contain two (from the available data) indistinguishable copies of each genomic locus. Due to this, the standard approach performs very poorly on diploid organisms. We prove that the 3D organization of the DNA is not identifiable from exclusively chromosome capture data for diploid organisms. In fact, there are infinitely many solutions even in the noise-free setting. We then discuss various additional biologically relevant constraints (including distances between neighboring genomic loci and to the nucleus center or higher-order interactions). Under these conditions we prove there are finitely many solutions and conjecture we in fact have identifiability. Finally, we provide SDP formulations for computing the 3D embedding of the DNA with these additional constraints and show that we can recover the true 3D embedding with high accuracy even under noise.
by Lawrence Sun.
M. Eng.
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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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Almagro, Sébastien. "Organisation structurale et fonctionnelle des chromosomes." Phd thesis, Université Joseph Fourier (Grenoble), 2003. http://tel.archives-ouvertes.fr/tel-00003099.

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Nous avons utilisé une technique récente de mesure d'élasticité de chromosomes mitotiques assemblés in vitro de Xénope et mis au point une technique de fonctionnalisation par anticorps de micropipettes. Nous avons confirmé que le chromosome mitotique n'était pas un objet homogène. Il est constitué de deux parties bien distinctes : une gaine molle de chromatine et une structure rigide. Nous avons identifié les protéines SMC comme actrices de ces structures rigides. Nous avons aussi montré que l'ADN et les protéines sont nécessaires au maintien de l'organisation des chromosomes alors que l'ARN ne l'est pas. Nous avons aussi étudié le paysage énergétique du chromosome, ce qui n'avait jamais été réalisé sur un objet aussi complexe. Nous proposons un modèle dynamique de formation des chromosomes dans lequel les protéines SMC agissent comme médiatrices de la forme en bâtonnet des chromosomes mitotiques et dans lequel les ions Mg++ et Ca++ jouent le rôle d'agents de
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Nourse, Jamie. "The structure, organisation and function of dispensable chromosomes in the phytopathogenic fungus Colltotrichum Gloeosporioides /." St. Lucia, Qld, 2001. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16086.pdf.

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Di, Stefano Marco. "Structure and dynamics of entangled biopolymers: from knotted DNA to chromosomes." Doctoral thesis, SISSA, 2014. http://hdl.handle.net/20.500.11767/3886.

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Brinkman, Jacquelyn N. "Structure and evolution of supernumerary chromosomes in the Pacific Giant salamander Dicamptodon tenebrosus." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0028/MQ50727.pdf.

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Wright, Matthew A. "Approaches to determining the three-dimensional structure and dynamics of bacterial chromosomes." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33653.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.
Vita.
Includes bibliographical references.
The information in genomes is only partially contained in the linear sequence of their nucleotides. Their folding into dynamic three-dimensional structures creates spatial relationships between loci that likely play important functional roles. Yet so far only the broad outlines of this spatial organization have been discerned. In chapter 2 of this thesis I describe a general constraint-based framework for defining the configuration space of chromosomes. Analogous to protein structure determination through NMR, such a framework allows the quantitative reduction of the conformation space down to the level of a single structure or an ensemble of structures. It is compatible with both experimentally determined and theoretical constraints, particularly those motivated by evolutionary optimality. In chapter 3., I describe the first method to search for signals of large-scale three- dimensional structure in genome sequences. The results suggest that there is strong selection for three-dimensional relationships within the chromosome, particularly those related to transcription. The signals generated recapitulate both known structural data from microscopy and functional data on genome-wide transcription levels.
(cont.) Moreover, a detailed analysis of these signals in E. coli suggests previously unknown structural features including chromosome-long periodic looping and an axis of high transcriptional activity. There are immediate applications to other bacteria and potentially to eukaryotes.
by Matthew A. Wright.
Ph.D.
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Cinato, Elisa. "Structure et expression du gène IFNA R2 humain : identification de la deuxième chaîne du récepteur des interférons alpha/bêta." Montpellier 2, 1996. http://www.theses.fr/1996MON20042.

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Seule la premiere chaine du recepteur des ifn-alpha/beta avait ete caracterisee. Nous avons clone le gene ifnar2, qui appartient au groupe de genes de recepteurs des cytokines sur le chromosome 21 humain. Le gene ifnar2 est a l'origine de quatre messagers differents, codant pour trois proteines. Une est secretee, deux sont des proteines transmembranaires, partageant le meme domaine extracellulaire, mais avec queue cytoplasmique differente. Nous avons montre, par complementation dans les cellules humaines mutantes u5, que la proteine avec domaine intracellulaire long est un composant fonctionnel du recepteur des ifn-alpha/beta humain
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Jefferson, Andrew. "Chromosomes structure, nuclear architecture and the regulation of gene expression in ICF syndrome." Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442821.

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Books on the topic "Structure des chromosomes"

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

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Human chromosomes: Structure, behavior, effects. New York, New York, USA: Springer-Verlag, 1986.

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Therman, Eeva. Human chromosomes: Structure, behavior, and effects. 3rd ed. New York: Springer-Verlag, 1993.

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

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

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Hennig, Wolfgang, ed. Structure and Function of Eukaryotic Chromosomes. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-540-47783-9.

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1941-, Hennig Wolfgang, ed. Structure and function of eukaryotic chromosomes. Berlin: Springer-Verlag, 1987.

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

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Chromatin: Structure and function. London: Academic Press, 1992.

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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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Book chapters on the topic "Structure des chromosomes"

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Clark, M. S., and W. J. Wall. "Chromatin structure and replication." In Chromosomes, 1–26. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0073-8_1.

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Douglas, Ryan N., and James A. Birchler. "B Chromosomes." In 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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Pombo, A., J. McManus, T. A. Hughes, F. J. Iborra, D. A. Jackson, and P. R. Cook. "Transcription factories and chromosome structure." In Chromosomes Today, 147–60. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-009-1537-4_10.

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Verni’, F., M. P. Somma, R. Gandhi, M. L. Goldberg, and M. Gatti. "Genes controlling chromosome structure in Drosophila melanogaster." In Chromosomes Today, 87–103. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-009-1537-4_6.

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Meehan, R., P. Jeppesen, J. Lewis, and A. Bird. "Methylated DNA-binding proteins and chromatin structure." In Chromosomes Today, 377–89. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1510-0_29.

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Therman, Eeva, and Millard Susman. "Functional Structure of the Human X Chromosome." In Human Chromosomes, 228–36. New York, NY: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4684-0529-3_23.

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Favilla, Bianca Pereira, Luciana Amaral Haddad, and Maria Isabel Melaragno. "Human Chromosomes." In Human Genome Structure, Function and Clinical Considerations, 25–58. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-73151-9_2.

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Therman, Eeva. "Structure of the Eukaryotic Chromosome and the Karyotype." In Human Chromosomes, 13–24. New York, NY: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-0269-8_2.

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Therman, Eeva. "Fine Structure and Function of the Eukaryotic Chromosome." In Human Chromosomes, 58–64. New York, NY: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-0269-8_6.

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Therman, Eeva, and Millard Susman. "Structure of the Eukaryotic Chromosome and the Karyotype." In Human Chromosomes, 14–25. New York, NY: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4684-0529-3_2.

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Conference papers on the topic "Structure des chromosomes"

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NOBLE, WILLIAM STAFFORD, C. ANTHONY BLAU, JOB DEKKER, ZHI-JUN DUAN, and YI MAO. "THE STRUCTURE AND FUNCTION OF CHROMATIN AND CHROMOSOMES." In Proceedings of the Pacific Symposium. WORLD SCIENTIFIC, 2011. http://dx.doi.org/10.1142/9789814366496_0042.

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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." In 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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Chapman, Colin D., Kazuhiro Saitou, and Mark J. Jakiela. "Genetic Algorithms As an Approach to Configuration and Topology Design." In ASME 1993 Design Technical Conferences. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/detc1993-0338.

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Abstract The Genetic Algorithm, a search and optimization technique based on the theory of natural selection, is applied to problems of structural topology optimization. Given a structure’s boundary conditions and maximum allowable design domain, a discretized design representation is created. Populations of genetic algorithm “chromosomes” are then mapped into the design representation, creating potentially optimal structure topologies. Utilizing genetics-based operators such as crossover and mutation, generations of increasingly-desirable structure topologies are created. In this paper, the use of the genetic algorithm (GA) in structural topology optimization is presented. An overview of the genetic algorithm will describe the genetics-based representations and operators used in a typical genetic algorithm search. After defining topology optimization and its relation to the broader area of structural optimization, a review of previous research in GA-based and non-GA-based structural optimization is provided. The design representations, and methods for mapping genetic algorithm “chromosomes” into structure topology representations, are then detailed. Several examples of genetic algorithm-based structural topology optimization are provided: we address the optimization of beam cross-section topologies and cantilevered plate topologies, and we also investigate efficient techniques for using finite element analysis in a genetic algorithm-based search. Finally, a description of potential future work in genetic algorithm-based structural topology optimization is offered.
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Țurcan, Ana, Olesea Borozan, Silvia Munteanu, Constantin Ababii, Ana Nistiriuc, Andrei Șestacov, Vadim Struna, and Victor Lașco. "Multi-Criteria Distributed Decision-Making System Based on Genetic Algorithms." In 11th International Conference on “Electronics, Communications and Computing". Technical University of Moldova, 2022. http://dx.doi.org/10.52326/ic-ecco.2021/ce.06.

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This thesis comprises the results of designing a distributed decision-making system in multi-criteria areas. The distributed decision-making system is the architecture of homogenous data-processing devices that form a Wireless network with Mesh topology. The decision-making process is based on finding an optimal solution that is implemented through the use of genetic algorithms. Aiming to identify the initial population of the genetic algorithm, there shall be calculated the partial derivative for each variable for the ordered process. The results of partial derivative serve as an identifier of values from the Chromosome structure. There have been developed in this thesis: general algorithm of system functioning; population structure formed of Chromosomes and Genes; methodology of calculation of component values of the initial population; and an example of implementation of the distributed decision-making system based on Node MCU ESP32 devices.
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"The divergence of wheat 5B chromosomes during evolution and its impact on recombination suppression." In 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-2022-361.

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Lee, C. H., H. Teng, and J. S. Chen. "Atomistic to Continuum Modeling of DNA Molecules." In ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13157.

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The mechanical properties of DNA has very important biological implication. For example, the bending and twisting rigidities of DNA affect how it wraps around histones to form chromosomes, bends upon interactions with proteins, supercoils during replication process, and packs into the confined space within a virus. Many biologically important processes involving DNA are accompanied by the deformations of double helical structure of DNA.
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Guttmann, G. D., and J. A. Cobble. "Soft x-ray imaging of biological materials at Los Alamos National Laboratory." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.mp4.

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Soft x-ray contact microscopy (SXCM) is a form of x-ray lithography; however, the biological cell is imaged. Imaging of the biological sample is by soft x- rays within the "water window," which has an energy range of 277–525 eV. The contrast mechanism is based upon the x-ray absorption lengths of carbon and nitrogen, which are ~10 times shorter than that of oxygen in the "water window." In previous experiments at the Lawrence Livermore National Laboratory PHOENIX laser facility, the major result was the first high-resolution (~30 nm) x-ray micrographs of living mammalian cells, CHO-SC1. One of the images showed chromosomes in the mitotic stage. Future efforts at Los Alamos National Laboratory will be the utilization of the Free Electron Laser and in-house laser-produced plasmas as x-ray sources, the use of atomic force microscopy to read the resists, the development of thin window technology and resist applications, the use of multilayer and Fresnel zone plate x-ray optics for holographic purposes, and the use of biological agents to enhance the x-ray images of key cellular structures. Biological studies will look at the structure of chromosomes and chromatin in the living cell.
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"A novel, computationally tractable algorithm flags in big matrices every column associated in any way with others or a dependent variable, with much higher power when columns are linked like mutations in chromosomes." In 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-2022-648.

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Bosma, P. J., E. A. van den Berg, and T. Kooistra. "ISOLATION OF THE GENE CODING FOR HUMAN PLASMINOGEN ACTIVATOR INHIBITOR TYPE 1 (PAI-1)." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644440.

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A human placenta genomic DNA cosmid library was screened for the presence of the PAI-1 gene using a cDNA probe coding for PAI-1. Two overlapping recombinant cosmids were obtained that contain human DNA spanning 55 kb. The cosmids were mapped using 3' and 5' end probes isolated from an almost full-length cDNA clone of 2.5 kb. The two cosmids were found to contain the entire structural PAI-1 gene (approximately 15 kb) and also included 25 kb 5' flanking sequences. The transcription initiation site was identified by SI nuclease protection experiments and the promotor region was sequenced. Further experiments will be directed at characterizing the regulatory elements of the PAI-1 gene.In order to determine the chromosomal localization of the PAI-1 gene we have hybridized our genomic clones in situ to metaphase chromosomes of a human blood cell culture. Preliminary experiments show a specific hybridization signal which will enable us to sublocalize the chromosomal position of the PAI-1 gene.
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"Chromosome synapsis and recombination in intraspecific and interspecific heterozygotes for chromosomal rearrangements in voles of the genus Alexandromys." In 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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Reports on the topic "Structure des chromosomes"

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Pawlowski, Wojtek P., and Avraham A. Levy. What shapes the crossover landscape in maize and wheat and how can we modify it. United States Department of Agriculture, January 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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Rill, R. The impact of energy related pollutants on chromosome structure. Office of Scientific and Technical Information (OSTI), October 1989. http://dx.doi.org/10.2172/5345926.

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Breiman, Adina, Jan Dvorak, Abraham Korol, and 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, December 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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Shapiro, Daniel Benjamin. Polarized light scattering as a probe for changes in chromosome structure. Office of Scientific and Technical Information (OSTI), October 1993. http://dx.doi.org/10.2172/10107208.

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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), November 1997. http://dx.doi.org/10.2172/548675.

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Glesne, D., E. Huberman, F. Collart, T. Varkony, and H. Drabkin. Chromosomal localization and structure of the human type II IMP dehydrogenase gene. Office of Scientific and Technical Information (OSTI), May 1994. http://dx.doi.org/10.2172/10148872.

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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), March 1998. http://dx.doi.org/10.2172/607511.

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Medrano, Juan, Adam Friedmann, Moshe (Morris) Soller, Ehud Lipkin, and Abraham Korol. High resolution linkage disequilibrium mapping of QTL affecting milk production traits in Israel Holstein dairy cattle. United States Department of Agriculture, March 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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Sela, Hanan, Eduard Akhunov, and Brian J. Steffenson. Population genomics, linkage disequilibrium and association mapping of stripe rust resistance genes in wild emmer wheat, Triticum turgidum ssp. dicoccoides. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598170.bard.

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The primary goals of this project were: (1) development of a genetically characterized association panel of wild emmer for high resolution analysis of the genetic basis of complex traits; (2) characterization and mapping of genes and QTL for seedling and adult plant resistance to stripe rust in wild emmer populations; (3) characterization of LD patterns along wild emmer chromosomes; (4) elucidation of the multi-locus genetic structure of wild emmer populations and its correlation with geo-climatic variables at the collection sites. Introduction In recent years, Stripe (yellow) rust (Yr) caused by Pucciniastriiformis f. sp. tritici(PST) has become a major threat to wheat crops in many parts of the world. New races have overcome most of the known resistances. It is essential, therefore, that the search for new genes will continue, followed by their mapping by molecular markers and introgression into the elite varieties by marker-assisted selection (MAS). The reservoir of genes for disease and pest resistance in wild emmer wheat (Triticumdicoccoides) is an important resource that must be made available to wheat breeders. The majority of resistance genes that were introgressed so far in cultivated wheat are resistance (R) genes. These genes, though confering near-immunity from the seedling stage, are often overcome by the pathogen in a short period after being deployed over vast production areas. On the other hand, adult-plant resistance (APR) is usually more durable since it is, in many cases, polygenic and confers partial resistance that may put less selective pressure on the pathogen. In this project, we have screened a collection of 480 wild emmer accessions originating from Israel for APR and seedling resistance to PST. Seedling resistance was tested against one Israeli and 3 North American PST isolates. APR was tested on accessions that did not have seedling resistance. The APR screen was conducted in two fields in Israel and in one field in the USA over 3 years for a total of 11 replicates. We have found about 20 accessions that have moderate stripe rust APR with infection type (IT<5), and about 20 additional accessions that have novel seedling resistance (IT<3). We have genotyped the collection using genotyping by sequencing (GBS) and the 90K SNP chip array. GBS yielded a total 341K SNP that were filtered to 150K informative SNP. The 90K assay resulted in 11K informative SNP. We have conducted a genome-wide association scan (GWAS) and found one significant locus on 6BL ( -log p >5). Two novel loci were found for seedling resistance. Further investigation of the 6BL locus and the effect of Yr36 showed that the 6BL locus and the Yr36 have additive effect and that the presence of favorable alleles of both loci results in reduction of 2 grades in the IT score. To identify alleles conferring adaption to extreme climatic conditions, we have associated the patterns of genomic variation in wild emmer with historic climate data from the accessions’ collection sites. The analysis of population stratification revealed four genetically distinct groups of wild emmer accessions coinciding with their geographic distribution. Partitioning of genomic variance showed that geographic location and climate together explain 43% of SNPs among emmer accessions with 19% of SNPs affected by climatic factors. The top three bioclimatic factors driving SNP distribution were temperature seasonality, precipitation seasonality, and isothermality. Association mapping approaches revealed 57 SNPs associated with these bio-climatic variables. Out of 21 unique genomic regions controlling heading date variation, 10 (~50%) overlapped with SNPs showing significant association with at least one of the three bioclimatic variables. This result suggests that a substantial part of the genomic variation associated with local adaptation in wild emmer is driven by selection acting on loci regulating flowering. Conclusions: Wild emmer can serve as a good source for novel APR and seedling R genes for stripe rust resistance. APR for stripe rust is a complex trait conferred by several loci that may have an additive effect. GWAS is feasible in the wild emmer population, however, its detection power is limited. A panel of wild emmer tagged with more than 150K SNP is available for further GWAS of important traits. The insights gained by the bioclimatic-gentic associations should be taken into consideration when planning conservation strategies.
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Fallik, Elazar, Robert Joly, Ilan Paran, and Matthew A. Jenks. Study of the Physiological, Molecular and Genetic Factors Associated with Postharvest Water Loss in Pepper Fruit. United States Department of Agriculture, December 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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